1 /*
   2  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #if !defined(__clang_major__) && defined(__GNUC__)
  26 // FIXME, formats have issues.  Disable this macro definition, compile, and study warnings for more information.
  27 #define ATTRIBUTE_PRINTF(x,y)
  28 #endif
  29 
  30 #include "precompiled.hpp"
  31 #include "classfile/stringTable.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "code/icBuffer.hpp"
  34 #include "gc_implementation/g1/bufferingOopClosure.hpp"
  35 #include "gc_implementation/g1/concurrentG1Refine.hpp"
  36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
  37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
  38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
  39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
  40 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
  41 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
  42 #include "gc_implementation/g1/g1EvacFailure.hpp"
  43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
  44 #include "gc_implementation/g1/g1Log.hpp"
  45 #include "gc_implementation/g1/g1MarkSweep.hpp"
  46 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
  47 #include "gc_implementation/g1/g1RemSet.inline.hpp"
  48 #include "gc_implementation/g1/g1StringDedup.hpp"
  49 #include "gc_implementation/g1/g1YCTypes.hpp"
  50 #include "gc_implementation/g1/heapRegion.inline.hpp"
  51 #include "gc_implementation/g1/heapRegionRemSet.hpp"
  52 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
  53 #include "gc_implementation/g1/vm_operations_g1.hpp"
  54 #include "gc_implementation/shared/gcHeapSummary.hpp"
  55 #include "gc_implementation/shared/gcTimer.hpp"
  56 #include "gc_implementation/shared/gcTrace.hpp"
  57 #include "gc_implementation/shared/gcTraceTime.hpp"
  58 #include "gc_implementation/shared/isGCActiveMark.hpp"
  59 #include "memory/gcLocker.inline.hpp"
  60 #include "memory/generationSpec.hpp"
  61 #include "memory/iterator.hpp"
  62 #include "memory/referenceProcessor.hpp"
  63 #include "oops/oop.inline.hpp"
  64 #include "oops/oop.pcgc.inline.hpp"
  65 #include "runtime/orderAccess.inline.hpp"
  66 #include "runtime/vmThread.hpp"
  67 #include "utilities/globalDefinitions.hpp"
  68 #include "utilities/ticks.hpp"
  69 
  70 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
  71 
  72 // turn it on so that the contents of the young list (scan-only /
  73 // to-be-collected) are printed at "strategic" points before / during
  74 // / after the collection --- this is useful for debugging
  75 #define YOUNG_LIST_VERBOSE 0
  76 // CURRENT STATUS
  77 // This file is under construction.  Search for "FIXME".
  78 
  79 // INVARIANTS/NOTES
  80 //
  81 // All allocation activity covered by the G1CollectedHeap interface is
  82 // serialized by acquiring the HeapLock.  This happens in mem_allocate
  83 // and allocate_new_tlab, which are the "entry" points to the
  84 // allocation code from the rest of the JVM.  (Note that this does not
  85 // apply to TLAB allocation, which is not part of this interface: it
  86 // is done by clients of this interface.)
  87 
  88 // Notes on implementation of parallelism in different tasks.
  89 //
  90 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
  91 // The number of GC workers is passed to heap_region_par_iterate_chunked().
  92 // It does use run_task() which sets _n_workers in the task.
  93 // G1ParTask executes g1_process_strong_roots() ->
  94 // SharedHeap::process_strong_roots() which calls eventually to
  95 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
  96 // SequentialSubTasksDone.  SharedHeap::process_strong_roots() also
  97 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
  98 //
  99 
 100 // Local to this file.
 101 
 102 class RefineCardTableEntryClosure: public CardTableEntryClosure {
 103   bool _concurrent;
 104 public:
 105   RefineCardTableEntryClosure() : _concurrent(true) { }
 106 
 107   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 108     bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
 109     // This path is executed by the concurrent refine or mutator threads,
 110     // concurrently, and so we do not care if card_ptr contains references
 111     // that point into the collection set.
 112     assert(!oops_into_cset, "should be");
 113 
 114     if (_concurrent && SuspendibleThreadSet::should_yield()) {
 115       // Caller will actually yield.
 116       return false;
 117     }
 118     // Otherwise, we finished successfully; return true.
 119     return true;
 120   }
 121 
 122   void set_concurrent(bool b) { _concurrent = b; }
 123 };
 124 
 125 
 126 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
 127   size_t _num_processed;
 128   CardTableModRefBS* _ctbs;
 129   int _histo[256];
 130 
 131  public:
 132   ClearLoggedCardTableEntryClosure() :
 133     _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
 134   {
 135     for (int i = 0; i < 256; i++) _histo[i] = 0;
 136   }
 137 
 138   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 139     unsigned char* ujb = (unsigned char*)card_ptr;
 140     int ind = (int)(*ujb);
 141     _histo[ind]++;
 142 
 143     *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
 144     _num_processed++;
 145 
 146     return true;
 147   }
 148 
 149   size_t num_processed() { return _num_processed; }
 150 
 151   void print_histo() {
 152     gclog_or_tty->print_cr("Card table value histogram:");
 153     for (int i = 0; i < 256; i++) {
 154       if (_histo[i] != 0) {
 155         gclog_or_tty->print_cr("  %d: %d", i, _histo[i]);
 156       }
 157     }
 158   }
 159 };
 160 
 161 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
 162  private:
 163   size_t _num_processed;
 164 
 165  public:
 166   RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
 167 
 168   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
 169     *card_ptr = CardTableModRefBS::dirty_card_val();
 170     _num_processed++;
 171     return true;
 172   }
 173 
 174   size_t num_processed() const { return _num_processed; }
 175 };
 176 
 177 YoungList::YoungList(G1CollectedHeap* g1h) :
 178     _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
 179     _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
 180   guarantee(check_list_empty(false), "just making sure...");
 181 }
 182 
 183 void YoungList::push_region(HeapRegion *hr) {
 184   assert(!hr->is_young(), "should not already be young");
 185   assert(hr->get_next_young_region() == NULL, "cause it should!");
 186 
 187   hr->set_next_young_region(_head);
 188   _head = hr;
 189 
 190   _g1h->g1_policy()->set_region_eden(hr, (int) _length);
 191   ++_length;
 192 }
 193 
 194 void YoungList::add_survivor_region(HeapRegion* hr) {
 195   assert(hr->is_survivor(), "should be flagged as survivor region");
 196   assert(hr->get_next_young_region() == NULL, "cause it should!");
 197 
 198   hr->set_next_young_region(_survivor_head);
 199   if (_survivor_head == NULL) {
 200     _survivor_tail = hr;
 201   }
 202   _survivor_head = hr;
 203   ++_survivor_length;
 204 }
 205 
 206 void YoungList::empty_list(HeapRegion* list) {
 207   while (list != NULL) {
 208     HeapRegion* next = list->get_next_young_region();
 209     list->set_next_young_region(NULL);
 210     list->uninstall_surv_rate_group();
 211     list->set_not_young();
 212     list = next;
 213   }
 214 }
 215 
 216 void YoungList::empty_list() {
 217   assert(check_list_well_formed(), "young list should be well formed");
 218 
 219   empty_list(_head);
 220   _head = NULL;
 221   _length = 0;
 222 
 223   empty_list(_survivor_head);
 224   _survivor_head = NULL;
 225   _survivor_tail = NULL;
 226   _survivor_length = 0;
 227 
 228   _last_sampled_rs_lengths = 0;
 229 
 230   assert(check_list_empty(false), "just making sure...");
 231 }
 232 
 233 bool YoungList::check_list_well_formed() {
 234   bool ret = true;
 235 
 236   uint length = 0;
 237   HeapRegion* curr = _head;
 238   HeapRegion* last = NULL;
 239   while (curr != NULL) {
 240     if (!curr->is_young()) {
 241       gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
 242                              "incorrectly tagged (y: %d, surv: %d)",
 243                              curr->bottom(), curr->end(),
 244                              curr->is_young(), curr->is_survivor());
 245       ret = false;
 246     }
 247     ++length;
 248     last = curr;
 249     curr = curr->get_next_young_region();
 250   }
 251   ret = ret && (length == _length);
 252 
 253   if (!ret) {
 254     gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
 255     gclog_or_tty->print_cr("###   list has %u entries, _length is %u",
 256                            length, _length);
 257   }
 258 
 259   return ret;
 260 }
 261 
 262 bool YoungList::check_list_empty(bool check_sample) {
 263   bool ret = true;
 264 
 265   if (_length != 0) {
 266     gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
 267                   _length);
 268     ret = false;
 269   }
 270   if (check_sample && _last_sampled_rs_lengths != 0) {
 271     gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
 272     ret = false;
 273   }
 274   if (_head != NULL) {
 275     gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
 276     ret = false;
 277   }
 278   if (!ret) {
 279     gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
 280   }
 281 
 282   return ret;
 283 }
 284 
 285 void
 286 YoungList::rs_length_sampling_init() {
 287   _sampled_rs_lengths = 0;
 288   _curr               = _head;
 289 }
 290 
 291 bool
 292 YoungList::rs_length_sampling_more() {
 293   return _curr != NULL;
 294 }
 295 
 296 void
 297 YoungList::rs_length_sampling_next() {
 298   assert( _curr != NULL, "invariant" );
 299   size_t rs_length = _curr->rem_set()->occupied();
 300 
 301   _sampled_rs_lengths += rs_length;
 302 
 303   // The current region may not yet have been added to the
 304   // incremental collection set (it gets added when it is
 305   // retired as the current allocation region).
 306   if (_curr->in_collection_set()) {
 307     // Update the collection set policy information for this region
 308     _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
 309   }
 310 
 311   _curr = _curr->get_next_young_region();
 312   if (_curr == NULL) {
 313     _last_sampled_rs_lengths = _sampled_rs_lengths;
 314     // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
 315   }
 316 }
 317 
 318 void
 319 YoungList::reset_auxilary_lists() {
 320   guarantee( is_empty(), "young list should be empty" );
 321   assert(check_list_well_formed(), "young list should be well formed");
 322 
 323   // Add survivor regions to SurvRateGroup.
 324   _g1h->g1_policy()->note_start_adding_survivor_regions();
 325   _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
 326 
 327   int young_index_in_cset = 0;
 328   for (HeapRegion* curr = _survivor_head;
 329        curr != NULL;
 330        curr = curr->get_next_young_region()) {
 331     _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
 332 
 333     // The region is a non-empty survivor so let's add it to
 334     // the incremental collection set for the next evacuation
 335     // pause.
 336     _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
 337     young_index_in_cset += 1;
 338   }
 339   assert((uint) young_index_in_cset == _survivor_length, "post-condition");
 340   _g1h->g1_policy()->note_stop_adding_survivor_regions();
 341 
 342   _head   = _survivor_head;
 343   _length = _survivor_length;
 344   if (_survivor_head != NULL) {
 345     assert(_survivor_tail != NULL, "cause it shouldn't be");
 346     assert(_survivor_length > 0, "invariant");
 347     _survivor_tail->set_next_young_region(NULL);
 348   }
 349 
 350   // Don't clear the survivor list handles until the start of
 351   // the next evacuation pause - we need it in order to re-tag
 352   // the survivor regions from this evacuation pause as 'young'
 353   // at the start of the next.
 354 
 355   _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
 356 
 357   assert(check_list_well_formed(), "young list should be well formed");
 358 }
 359 
 360 void YoungList::print() {
 361   HeapRegion* lists[] = {_head,   _survivor_head};
 362   const char* names[] = {"YOUNG", "SURVIVOR"};
 363 
 364   for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
 365     gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
 366     HeapRegion *curr = lists[list];
 367     if (curr == NULL)
 368       gclog_or_tty->print_cr("  empty");
 369     while (curr != NULL) {
 370       gclog_or_tty->print_cr("  "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
 371                              HR_FORMAT_PARAMS(curr),
 372                              curr->prev_top_at_mark_start(),
 373                              curr->next_top_at_mark_start(),
 374                              curr->age_in_surv_rate_group_cond());
 375       curr = curr->get_next_young_region();
 376     }
 377   }
 378 
 379   gclog_or_tty->cr();
 380 }
 381 
 382 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
 383 {
 384   // Claim the right to put the region on the dirty cards region list
 385   // by installing a self pointer.
 386   HeapRegion* next = hr->get_next_dirty_cards_region();
 387   if (next == NULL) {
 388     HeapRegion* res = (HeapRegion*)
 389       Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
 390                           NULL);
 391     if (res == NULL) {
 392       HeapRegion* head;
 393       do {
 394         // Put the region to the dirty cards region list.
 395         head = _dirty_cards_region_list;
 396         next = (HeapRegion*)
 397           Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
 398         if (next == head) {
 399           assert(hr->get_next_dirty_cards_region() == hr,
 400                  "hr->get_next_dirty_cards_region() != hr");
 401           if (next == NULL) {
 402             // The last region in the list points to itself.
 403             hr->set_next_dirty_cards_region(hr);
 404           } else {
 405             hr->set_next_dirty_cards_region(next);
 406           }
 407         }
 408       } while (next != head);
 409     }
 410   }
 411 }
 412 
 413 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
 414 {
 415   HeapRegion* head;
 416   HeapRegion* hr;
 417   do {
 418     head = _dirty_cards_region_list;
 419     if (head == NULL) {
 420       return NULL;
 421     }
 422     HeapRegion* new_head = head->get_next_dirty_cards_region();
 423     if (head == new_head) {
 424       // The last region.
 425       new_head = NULL;
 426     }
 427     hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
 428                                           head);
 429   } while (hr != head);
 430   assert(hr != NULL, "invariant");
 431   hr->set_next_dirty_cards_region(NULL);
 432   return hr;
 433 }
 434 
 435 void G1CollectedHeap::stop_conc_gc_threads() {
 436   _cg1r->stop();
 437   _cmThread->stop();
 438   if (G1StringDedup::is_enabled()) {
 439     G1StringDedup::stop();
 440   }
 441 }
 442 
 443 #ifdef ASSERT
 444 // A region is added to the collection set as it is retired
 445 // so an address p can point to a region which will be in the
 446 // collection set but has not yet been retired.  This method
 447 // therefore is only accurate during a GC pause after all
 448 // regions have been retired.  It is used for debugging
 449 // to check if an nmethod has references to objects that can
 450 // be move during a partial collection.  Though it can be
 451 // inaccurate, it is sufficient for G1 because the conservative
 452 // implementation of is_scavengable() for G1 will indicate that
 453 // all nmethods must be scanned during a partial collection.
 454 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
 455   if (p == NULL) {
 456     return false;
 457   }
 458   return heap_region_containing(p)->in_collection_set();
 459 }
 460 #endif
 461 
 462 // Returns true if the reference points to an object that
 463 // can move in an incremental collection.
 464 bool G1CollectedHeap::is_scavengable(const void* p) {
 465   HeapRegion* hr = heap_region_containing(p);
 466   return !hr->isHumongous();
 467 }
 468 
 469 void G1CollectedHeap::check_ct_logs_at_safepoint() {
 470   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
 471   CardTableModRefBS* ct_bs = g1_barrier_set();
 472 
 473   // Count the dirty cards at the start.
 474   CountNonCleanMemRegionClosure count1(this);
 475   ct_bs->mod_card_iterate(&count1);
 476   int orig_count = count1.n();
 477 
 478   // First clear the logged cards.
 479   ClearLoggedCardTableEntryClosure clear;
 480   dcqs.apply_closure_to_all_completed_buffers(&clear);
 481   dcqs.iterate_closure_all_threads(&clear, false);
 482   clear.print_histo();
 483 
 484   // Now ensure that there's no dirty cards.
 485   CountNonCleanMemRegionClosure count2(this);
 486   ct_bs->mod_card_iterate(&count2);
 487   if (count2.n() != 0) {
 488     gclog_or_tty->print_cr("Card table has %d entries; %d originally",
 489                            count2.n(), orig_count);
 490   }
 491   guarantee(count2.n() == 0, "Card table should be clean.");
 492 
 493   RedirtyLoggedCardTableEntryClosure redirty;
 494   dcqs.apply_closure_to_all_completed_buffers(&redirty);
 495   dcqs.iterate_closure_all_threads(&redirty, false);
 496   gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
 497                          clear.num_processed(), orig_count);
 498   guarantee(redirty.num_processed() == clear.num_processed(),
 499             err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
 500                     redirty.num_processed(), clear.num_processed()));
 501 
 502   CountNonCleanMemRegionClosure count3(this);
 503   ct_bs->mod_card_iterate(&count3);
 504   if (count3.n() != orig_count) {
 505     gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
 506                            orig_count, count3.n());
 507     guarantee(count3.n() >= orig_count, "Should have restored them all.");
 508   }
 509 }
 510 
 511 // Private class members.
 512 
 513 G1CollectedHeap* G1CollectedHeap::_g1h;
 514 
 515 // Private methods.
 516 
 517 HeapRegion*
 518 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
 519   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
 520   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
 521     if (!_secondary_free_list.is_empty()) {
 522       if (G1ConcRegionFreeingVerbose) {
 523         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 524                                "secondary_free_list has %u entries",
 525                                _secondary_free_list.length());
 526       }
 527       // It looks as if there are free regions available on the
 528       // secondary_free_list. Let's move them to the free_list and try
 529       // again to allocate from it.
 530       append_secondary_free_list();
 531 
 532       assert(!_free_list.is_empty(), "if the secondary_free_list was not "
 533              "empty we should have moved at least one entry to the free_list");
 534       HeapRegion* res = _free_list.remove_region(is_old);
 535       if (G1ConcRegionFreeingVerbose) {
 536         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 537                                "allocated "HR_FORMAT" from secondary_free_list",
 538                                HR_FORMAT_PARAMS(res));
 539       }
 540       return res;
 541     }
 542 
 543     // Wait here until we get notified either when (a) there are no
 544     // more free regions coming or (b) some regions have been moved on
 545     // the secondary_free_list.
 546     SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
 547   }
 548 
 549   if (G1ConcRegionFreeingVerbose) {
 550     gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 551                            "could not allocate from secondary_free_list");
 552   }
 553   return NULL;
 554 }
 555 
 556 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
 557   assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
 558          "the only time we use this to allocate a humongous region is "
 559          "when we are allocating a single humongous region");
 560 
 561   HeapRegion* res;
 562   if (G1StressConcRegionFreeing) {
 563     if (!_secondary_free_list.is_empty()) {
 564       if (G1ConcRegionFreeingVerbose) {
 565         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 566                                "forced to look at the secondary_free_list");
 567       }
 568       res = new_region_try_secondary_free_list(is_old);
 569       if (res != NULL) {
 570         return res;
 571       }
 572     }
 573   }
 574 
 575   res = _free_list.remove_region(is_old);
 576 
 577   if (res == NULL) {
 578     if (G1ConcRegionFreeingVerbose) {
 579       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
 580                              "res == NULL, trying the secondary_free_list");
 581     }
 582     res = new_region_try_secondary_free_list(is_old);
 583   }
 584   if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
 585     // Currently, only attempts to allocate GC alloc regions set
 586     // do_expand to true. So, we should only reach here during a
 587     // safepoint. If this assumption changes we might have to
 588     // reconsider the use of _expand_heap_after_alloc_failure.
 589     assert(SafepointSynchronize::is_at_safepoint(), "invariant");
 590 
 591     ergo_verbose1(ErgoHeapSizing,
 592                   "attempt heap expansion",
 593                   ergo_format_reason("region allocation request failed")
 594                   ergo_format_byte("allocation request"),
 595                   word_size * HeapWordSize);
 596     if (expand(word_size * HeapWordSize)) {
 597       // Given that expand() succeeded in expanding the heap, and we
 598       // always expand the heap by an amount aligned to the heap
 599       // region size, the free list should in theory not be empty.
 600       // In either case remove_region() will check for NULL.
 601       res = _free_list.remove_region(is_old);
 602     } else {
 603       _expand_heap_after_alloc_failure = false;
 604     }
 605   }
 606   return res;
 607 }
 608 
 609 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
 610                                                         size_t word_size) {
 611   assert(isHumongous(word_size), "word_size should be humongous");
 612   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 613 
 614   uint first = G1_NULL_HRS_INDEX;
 615   if (num_regions == 1) {
 616     // Only one region to allocate, no need to go through the slower
 617     // path. The caller will attempt the expansion if this fails, so
 618     // let's not try to expand here too.
 619     HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
 620     if (hr != NULL) {
 621       first = hr->hrs_index();
 622     } else {
 623       first = G1_NULL_HRS_INDEX;
 624     }
 625   } else {
 626     // We can't allocate humongous regions while cleanupComplete() is
 627     // running, since some of the regions we find to be empty might not
 628     // yet be added to the free list and it is not straightforward to
 629     // know which list they are on so that we can remove them. Note
 630     // that we only need to do this if we need to allocate more than
 631     // one region to satisfy the current humongous allocation
 632     // request. If we are only allocating one region we use the common
 633     // region allocation code (see above).
 634     wait_while_free_regions_coming();
 635     append_secondary_free_list_if_not_empty_with_lock();
 636 
 637     if (free_regions() >= num_regions) {
 638       first = _hrs.find_contiguous(num_regions);
 639       if (first != G1_NULL_HRS_INDEX) {
 640         for (uint i = first; i < first + num_regions; ++i) {
 641           HeapRegion* hr = region_at(i);
 642           assert(hr->is_empty(), "sanity");
 643           assert(is_on_master_free_list(hr), "sanity");
 644           hr->set_pending_removal(true);
 645         }
 646         _free_list.remove_all_pending(num_regions);
 647       }
 648     }
 649   }
 650   return first;
 651 }
 652 
 653 HeapWord*
 654 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
 655                                                            uint num_regions,
 656                                                            size_t word_size) {
 657   assert(first != G1_NULL_HRS_INDEX, "pre-condition");
 658   assert(isHumongous(word_size), "word_size should be humongous");
 659   assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
 660 
 661   // Index of last region in the series + 1.
 662   uint last = first + num_regions;
 663 
 664   // We need to initialize the region(s) we just discovered. This is
 665   // a bit tricky given that it can happen concurrently with
 666   // refinement threads refining cards on these regions and
 667   // potentially wanting to refine the BOT as they are scanning
 668   // those cards (this can happen shortly after a cleanup; see CR
 669   // 6991377). So we have to set up the region(s) carefully and in
 670   // a specific order.
 671 
 672   // The word size sum of all the regions we will allocate.
 673   size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
 674   assert(word_size <= word_size_sum, "sanity");
 675 
 676   // This will be the "starts humongous" region.
 677   HeapRegion* first_hr = region_at(first);
 678   // The header of the new object will be placed at the bottom of
 679   // the first region.
 680   HeapWord* new_obj = first_hr->bottom();
 681   // This will be the new end of the first region in the series that
 682   // should also match the end of the last region in the series.
 683   HeapWord* new_end = new_obj + word_size_sum;
 684   // This will be the new top of the first region that will reflect
 685   // this allocation.
 686   HeapWord* new_top = new_obj + word_size;
 687 
 688   // First, we need to zero the header of the space that we will be
 689   // allocating. When we update top further down, some refinement
 690   // threads might try to scan the region. By zeroing the header we
 691   // ensure that any thread that will try to scan the region will
 692   // come across the zero klass word and bail out.
 693   //
 694   // NOTE: It would not have been correct to have used
 695   // CollectedHeap::fill_with_object() and make the space look like
 696   // an int array. The thread that is doing the allocation will
 697   // later update the object header to a potentially different array
 698   // type and, for a very short period of time, the klass and length
 699   // fields will be inconsistent. This could cause a refinement
 700   // thread to calculate the object size incorrectly.
 701   Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
 702 
 703   // We will set up the first region as "starts humongous". This
 704   // will also update the BOT covering all the regions to reflect
 705   // that there is a single object that starts at the bottom of the
 706   // first region.
 707   first_hr->set_startsHumongous(new_top, new_end);
 708 
 709   // Then, if there are any, we will set up the "continues
 710   // humongous" regions.
 711   HeapRegion* hr = NULL;
 712   for (uint i = first + 1; i < last; ++i) {
 713     hr = region_at(i);
 714     hr->set_continuesHumongous(first_hr);
 715   }
 716   // If we have "continues humongous" regions (hr != NULL), then the
 717   // end of the last one should match new_end.
 718   assert(hr == NULL || hr->end() == new_end, "sanity");
 719 
 720   // Up to this point no concurrent thread would have been able to
 721   // do any scanning on any region in this series. All the top
 722   // fields still point to bottom, so the intersection between
 723   // [bottom,top] and [card_start,card_end] will be empty. Before we
 724   // update the top fields, we'll do a storestore to make sure that
 725   // no thread sees the update to top before the zeroing of the
 726   // object header and the BOT initialization.
 727   OrderAccess::storestore();
 728 
 729   // Now that the BOT and the object header have been initialized,
 730   // we can update top of the "starts humongous" region.
 731   assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
 732          "new_top should be in this region");
 733   first_hr->set_top(new_top);
 734   if (_hr_printer.is_active()) {
 735     HeapWord* bottom = first_hr->bottom();
 736     HeapWord* end = first_hr->orig_end();
 737     if ((first + 1) == last) {
 738       // the series has a single humongous region
 739       _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
 740     } else {
 741       // the series has more than one humongous regions
 742       _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
 743     }
 744   }
 745 
 746   // Now, we will update the top fields of the "continues humongous"
 747   // regions. The reason we need to do this is that, otherwise,
 748   // these regions would look empty and this will confuse parts of
 749   // G1. For example, the code that looks for a consecutive number
 750   // of empty regions will consider them empty and try to
 751   // re-allocate them. We can extend is_empty() to also include
 752   // !continuesHumongous(), but it is easier to just update the top
 753   // fields here. The way we set top for all regions (i.e., top ==
 754   // end for all regions but the last one, top == new_top for the
 755   // last one) is actually used when we will free up the humongous
 756   // region in free_humongous_region().
 757   hr = NULL;
 758   for (uint i = first + 1; i < last; ++i) {
 759     hr = region_at(i);
 760     if ((i + 1) == last) {
 761       // last continues humongous region
 762       assert(hr->bottom() < new_top && new_top <= hr->end(),
 763              "new_top should fall on this region");
 764       hr->set_top(new_top);
 765       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
 766     } else {
 767       // not last one
 768       assert(new_top > hr->end(), "new_top should be above this region");
 769       hr->set_top(hr->end());
 770       _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
 771     }
 772   }
 773   // If we have continues humongous regions (hr != NULL), then the
 774   // end of the last one should match new_end and its top should
 775   // match new_top.
 776   assert(hr == NULL ||
 777          (hr->end() == new_end && hr->top() == new_top), "sanity");
 778   check_bitmaps("Humongous Region Allocation", first_hr);
 779 
 780   assert(first_hr->used() == word_size * HeapWordSize, "invariant");
 781   _summary_bytes_used += first_hr->used();
 782   _humongous_set.add(first_hr);
 783 
 784   return new_obj;
 785 }
 786 
 787 // If could fit into free regions w/o expansion, try.
 788 // Otherwise, if can expand, do so.
 789 // Otherwise, if using ex regions might help, try with ex given back.
 790 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
 791   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 792 
 793   verify_region_sets_optional();
 794 
 795   size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
 796   uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
 797   uint x_num = expansion_regions();
 798   uint fs = _hrs.free_suffix();
 799   uint first = humongous_obj_allocate_find_first(num_regions, word_size);
 800   if (first == G1_NULL_HRS_INDEX) {
 801     // The only thing we can do now is attempt expansion.
 802     if (fs + x_num >= num_regions) {
 803       // If the number of regions we're trying to allocate for this
 804       // object is at most the number of regions in the free suffix,
 805       // then the call to humongous_obj_allocate_find_first() above
 806       // should have succeeded and we wouldn't be here.
 807       //
 808       // We should only be trying to expand when the free suffix is
 809       // not sufficient for the object _and_ we have some expansion
 810       // room available.
 811       assert(num_regions > fs, "earlier allocation should have succeeded");
 812 
 813       ergo_verbose1(ErgoHeapSizing,
 814                     "attempt heap expansion",
 815                     ergo_format_reason("humongous allocation request failed")
 816                     ergo_format_byte("allocation request"),
 817                     word_size * HeapWordSize);
 818       if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
 819         // Even though the heap was expanded, it might not have
 820         // reached the desired size. So, we cannot assume that the
 821         // allocation will succeed.
 822         first = humongous_obj_allocate_find_first(num_regions, word_size);
 823       }
 824     }
 825   }
 826 
 827   HeapWord* result = NULL;
 828   if (first != G1_NULL_HRS_INDEX) {
 829     result =
 830       humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
 831     assert(result != NULL, "it should always return a valid result");
 832 
 833     // A successful humongous object allocation changes the used space
 834     // information of the old generation so we need to recalculate the
 835     // sizes and update the jstat counters here.
 836     g1mm()->update_sizes();
 837   }
 838 
 839   verify_region_sets_optional();
 840 
 841   return result;
 842 }
 843 
 844 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
 845   assert_heap_not_locked_and_not_at_safepoint();
 846   assert(!isHumongous(word_size), "we do not allow humongous TLABs");
 847 
 848   unsigned int dummy_gc_count_before;
 849   int dummy_gclocker_retry_count = 0;
 850   return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
 851 }
 852 
 853 HeapWord*
 854 G1CollectedHeap::mem_allocate(size_t word_size,
 855                               bool*  gc_overhead_limit_was_exceeded) {
 856   assert_heap_not_locked_and_not_at_safepoint();
 857 
 858   // Loop until the allocation is satisfied, or unsatisfied after GC.
 859   for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
 860     unsigned int gc_count_before;
 861 
 862     HeapWord* result = NULL;
 863     if (!isHumongous(word_size)) {
 864       result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
 865     } else {
 866       result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
 867     }
 868     if (result != NULL) {
 869       return result;
 870     }
 871 
 872     // Create the garbage collection operation...
 873     VM_G1CollectForAllocation op(gc_count_before, word_size);
 874     // ...and get the VM thread to execute it.
 875     VMThread::execute(&op);
 876 
 877     if (op.prologue_succeeded() && op.pause_succeeded()) {
 878       // If the operation was successful we'll return the result even
 879       // if it is NULL. If the allocation attempt failed immediately
 880       // after a Full GC, it's unlikely we'll be able to allocate now.
 881       HeapWord* result = op.result();
 882       if (result != NULL && !isHumongous(word_size)) {
 883         // Allocations that take place on VM operations do not do any
 884         // card dirtying and we have to do it here. We only have to do
 885         // this for non-humongous allocations, though.
 886         dirty_young_block(result, word_size);
 887       }
 888       return result;
 889     } else {
 890       if (gclocker_retry_count > GCLockerRetryAllocationCount) {
 891         return NULL;
 892       }
 893       assert(op.result() == NULL,
 894              "the result should be NULL if the VM op did not succeed");
 895     }
 896 
 897     // Give a warning if we seem to be looping forever.
 898     if ((QueuedAllocationWarningCount > 0) &&
 899         (try_count % QueuedAllocationWarningCount == 0)) {
 900       warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
 901     }
 902   }
 903 
 904   ShouldNotReachHere();
 905   return NULL;
 906 }
 907 
 908 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
 909                                            unsigned int *gc_count_before_ret,
 910                                            int* gclocker_retry_count_ret) {
 911   // Make sure you read the note in attempt_allocation_humongous().
 912 
 913   assert_heap_not_locked_and_not_at_safepoint();
 914   assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
 915          "be called for humongous allocation requests");
 916 
 917   // We should only get here after the first-level allocation attempt
 918   // (attempt_allocation()) failed to allocate.
 919 
 920   // We will loop until a) we manage to successfully perform the
 921   // allocation or b) we successfully schedule a collection which
 922   // fails to perform the allocation. b) is the only case when we'll
 923   // return NULL.
 924   HeapWord* result = NULL;
 925   for (int try_count = 1; /* we'll return */; try_count += 1) {
 926     bool should_try_gc;
 927     unsigned int gc_count_before;
 928 
 929     {
 930       MutexLockerEx x(Heap_lock);
 931 
 932       result = _mutator_alloc_region.attempt_allocation_locked(word_size,
 933                                                       false /* bot_updates */);
 934       if (result != NULL) {
 935         return result;
 936       }
 937 
 938       // If we reach here, attempt_allocation_locked() above failed to
 939       // allocate a new region. So the mutator alloc region should be NULL.
 940       assert(_mutator_alloc_region.get() == NULL, "only way to get here");
 941 
 942       if (GC_locker::is_active_and_needs_gc()) {
 943         if (g1_policy()->can_expand_young_list()) {
 944           // No need for an ergo verbose message here,
 945           // can_expand_young_list() does this when it returns true.
 946           result = _mutator_alloc_region.attempt_allocation_force(word_size,
 947                                                       false /* bot_updates */);
 948           if (result != NULL) {
 949             return result;
 950           }
 951         }
 952         should_try_gc = false;
 953       } else {
 954         // The GCLocker may not be active but the GCLocker initiated
 955         // GC may not yet have been performed (GCLocker::needs_gc()
 956         // returns true). In this case we do not try this GC and
 957         // wait until the GCLocker initiated GC is performed, and
 958         // then retry the allocation.
 959         if (GC_locker::needs_gc()) {
 960           should_try_gc = false;
 961         } else {
 962           // Read the GC count while still holding the Heap_lock.
 963           gc_count_before = total_collections();
 964           should_try_gc = true;
 965         }
 966       }
 967     }
 968 
 969     if (should_try_gc) {
 970       bool succeeded;
 971       result = do_collection_pause(word_size, gc_count_before, &succeeded,
 972           GCCause::_g1_inc_collection_pause);
 973       if (result != NULL) {
 974         assert(succeeded, "only way to get back a non-NULL result");
 975         return result;
 976       }
 977 
 978       if (succeeded) {
 979         // If we get here we successfully scheduled a collection which
 980         // failed to allocate. No point in trying to allocate
 981         // further. We'll just return NULL.
 982         MutexLockerEx x(Heap_lock);
 983         *gc_count_before_ret = total_collections();
 984         return NULL;
 985       }
 986     } else {
 987       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
 988         MutexLockerEx x(Heap_lock);
 989         *gc_count_before_ret = total_collections();
 990         return NULL;
 991       }
 992       // The GCLocker is either active or the GCLocker initiated
 993       // GC has not yet been performed. Stall until it is and
 994       // then retry the allocation.
 995       GC_locker::stall_until_clear();
 996       (*gclocker_retry_count_ret) += 1;
 997     }
 998 
 999     // We can reach here if we were unsuccessful in scheduling a
1000     // collection (because another thread beat us to it) or if we were
1001     // stalled due to the GC locker. In either can we should retry the
1002     // allocation attempt in case another thread successfully
1003     // performed a collection and reclaimed enough space. We do the
1004     // first attempt (without holding the Heap_lock) here and the
1005     // follow-on attempt will be at the start of the next loop
1006     // iteration (after taking the Heap_lock).
1007     result = _mutator_alloc_region.attempt_allocation(word_size,
1008                                                       false /* bot_updates */);
1009     if (result != NULL) {
1010       return result;
1011     }
1012 
1013     // Give a warning if we seem to be looping forever.
1014     if ((QueuedAllocationWarningCount > 0) &&
1015         (try_count % QueuedAllocationWarningCount == 0)) {
1016       warning("G1CollectedHeap::attempt_allocation_slow() "
1017               "retries %d times", try_count);
1018     }
1019   }
1020 
1021   ShouldNotReachHere();
1022   return NULL;
1023 }
1024 
1025 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1026                                           unsigned int * gc_count_before_ret,
1027                                           int* gclocker_retry_count_ret) {
1028   // The structure of this method has a lot of similarities to
1029   // attempt_allocation_slow(). The reason these two were not merged
1030   // into a single one is that such a method would require several "if
1031   // allocation is not humongous do this, otherwise do that"
1032   // conditional paths which would obscure its flow. In fact, an early
1033   // version of this code did use a unified method which was harder to
1034   // follow and, as a result, it had subtle bugs that were hard to
1035   // track down. So keeping these two methods separate allows each to
1036   // be more readable. It will be good to keep these two in sync as
1037   // much as possible.
1038 
1039   assert_heap_not_locked_and_not_at_safepoint();
1040   assert(isHumongous(word_size), "attempt_allocation_humongous() "
1041          "should only be called for humongous allocations");
1042 
1043   // Humongous objects can exhaust the heap quickly, so we should check if we
1044   // need to start a marking cycle at each humongous object allocation. We do
1045   // the check before we do the actual allocation. The reason for doing it
1046   // before the allocation is that we avoid having to keep track of the newly
1047   // allocated memory while we do a GC.
1048   if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1049                                            word_size)) {
1050     collect(GCCause::_g1_humongous_allocation);
1051   }
1052 
1053   // We will loop until a) we manage to successfully perform the
1054   // allocation or b) we successfully schedule a collection which
1055   // fails to perform the allocation. b) is the only case when we'll
1056   // return NULL.
1057   HeapWord* result = NULL;
1058   for (int try_count = 1; /* we'll return */; try_count += 1) {
1059     bool should_try_gc;
1060     unsigned int gc_count_before;
1061 
1062     {
1063       MutexLockerEx x(Heap_lock);
1064 
1065       // Given that humongous objects are not allocated in young
1066       // regions, we'll first try to do the allocation without doing a
1067       // collection hoping that there's enough space in the heap.
1068       result = humongous_obj_allocate(word_size);
1069       if (result != NULL) {
1070         return result;
1071       }
1072 
1073       if (GC_locker::is_active_and_needs_gc()) {
1074         should_try_gc = false;
1075       } else {
1076          // The GCLocker may not be active but the GCLocker initiated
1077         // GC may not yet have been performed (GCLocker::needs_gc()
1078         // returns true). In this case we do not try this GC and
1079         // wait until the GCLocker initiated GC is performed, and
1080         // then retry the allocation.
1081         if (GC_locker::needs_gc()) {
1082           should_try_gc = false;
1083         } else {
1084           // Read the GC count while still holding the Heap_lock.
1085           gc_count_before = total_collections();
1086           should_try_gc = true;
1087         }
1088       }
1089     }
1090 
1091     if (should_try_gc) {
1092       // If we failed to allocate the humongous object, we should try to
1093       // do a collection pause (if we're allowed) in case it reclaims
1094       // enough space for the allocation to succeed after the pause.
1095 
1096       bool succeeded;
1097       result = do_collection_pause(word_size, gc_count_before, &succeeded,
1098           GCCause::_g1_humongous_allocation);
1099       if (result != NULL) {
1100         assert(succeeded, "only way to get back a non-NULL result");
1101         return result;
1102       }
1103 
1104       if (succeeded) {
1105         // If we get here we successfully scheduled a collection which
1106         // failed to allocate. No point in trying to allocate
1107         // further. We'll just return NULL.
1108         MutexLockerEx x(Heap_lock);
1109         *gc_count_before_ret = total_collections();
1110         return NULL;
1111       }
1112     } else {
1113       if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1114         MutexLockerEx x(Heap_lock);
1115         *gc_count_before_ret = total_collections();
1116         return NULL;
1117       }
1118       // The GCLocker is either active or the GCLocker initiated
1119       // GC has not yet been performed. Stall until it is and
1120       // then retry the allocation.
1121       GC_locker::stall_until_clear();
1122       (*gclocker_retry_count_ret) += 1;
1123     }
1124 
1125     // We can reach here if we were unsuccessful in scheduling a
1126     // collection (because another thread beat us to it) or if we were
1127     // stalled due to the GC locker. In either can we should retry the
1128     // allocation attempt in case another thread successfully
1129     // performed a collection and reclaimed enough space.  Give a
1130     // warning if we seem to be looping forever.
1131 
1132     if ((QueuedAllocationWarningCount > 0) &&
1133         (try_count % QueuedAllocationWarningCount == 0)) {
1134       warning("G1CollectedHeap::attempt_allocation_humongous() "
1135               "retries %d times", try_count);
1136     }
1137   }
1138 
1139   ShouldNotReachHere();
1140   return NULL;
1141 }
1142 
1143 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1144                                        bool expect_null_mutator_alloc_region) {
1145   assert_at_safepoint(true /* should_be_vm_thread */);
1146   assert(_mutator_alloc_region.get() == NULL ||
1147                                              !expect_null_mutator_alloc_region,
1148          "the current alloc region was unexpectedly found to be non-NULL");
1149 
1150   if (!isHumongous(word_size)) {
1151     return _mutator_alloc_region.attempt_allocation_locked(word_size,
1152                                                       false /* bot_updates */);
1153   } else {
1154     HeapWord* result = humongous_obj_allocate(word_size);
1155     if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1156       g1_policy()->set_initiate_conc_mark_if_possible();
1157     }
1158     return result;
1159   }
1160 
1161   ShouldNotReachHere();
1162 }
1163 
1164 class PostMCRemSetClearClosure: public HeapRegionClosure {
1165   G1CollectedHeap* _g1h;
1166   ModRefBarrierSet* _mr_bs;
1167 public:
1168   PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1169     _g1h(g1h), _mr_bs(mr_bs) {}
1170 
1171   bool doHeapRegion(HeapRegion* r) {
1172     HeapRegionRemSet* hrrs = r->rem_set();
1173 
1174     if (r->continuesHumongous()) {
1175       // We'll assert that the strong code root list and RSet is empty
1176       assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1177       assert(hrrs->occupied() == 0, "RSet should be empty");
1178       return false;
1179     }
1180 
1181     _g1h->reset_gc_time_stamps(r);
1182     hrrs->clear();
1183     // You might think here that we could clear just the cards
1184     // corresponding to the used region.  But no: if we leave a dirty card
1185     // in a region we might allocate into, then it would prevent that card
1186     // from being enqueued, and cause it to be missed.
1187     // Re: the performance cost: we shouldn't be doing full GC anyway!
1188     _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1189 
1190     return false;
1191   }
1192 };
1193 
1194 void G1CollectedHeap::clear_rsets_post_compaction() {
1195   PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1196   heap_region_iterate(&rs_clear);
1197 }
1198 
1199 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1200   G1CollectedHeap*   _g1h;
1201   UpdateRSOopClosure _cl;
1202   int                _worker_i;
1203 public:
1204   RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1205     _cl(g1->g1_rem_set(), worker_i),
1206     _worker_i(worker_i),
1207     _g1h(g1)
1208   { }
1209 
1210   bool doHeapRegion(HeapRegion* r) {
1211     if (!r->continuesHumongous()) {
1212       _cl.set_from(r);
1213       r->oop_iterate(&_cl);
1214     }
1215     return false;
1216   }
1217 };
1218 
1219 class ParRebuildRSTask: public AbstractGangTask {
1220   G1CollectedHeap* _g1;
1221 public:
1222   ParRebuildRSTask(G1CollectedHeap* g1)
1223     : AbstractGangTask("ParRebuildRSTask"),
1224       _g1(g1)
1225   { }
1226 
1227   void work(uint worker_id) {
1228     RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1229     _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1230                                           _g1->workers()->active_workers(),
1231                                          HeapRegion::RebuildRSClaimValue);
1232   }
1233 };
1234 
1235 class PostCompactionPrinterClosure: public HeapRegionClosure {
1236 private:
1237   G1HRPrinter* _hr_printer;
1238 public:
1239   bool doHeapRegion(HeapRegion* hr) {
1240     assert(!hr->is_young(), "not expecting to find young regions");
1241     // We only generate output for non-empty regions.
1242     if (!hr->is_empty()) {
1243       if (!hr->isHumongous()) {
1244         _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1245       } else if (hr->startsHumongous()) {
1246         if (hr->region_num() == 1) {
1247           // single humongous region
1248           _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1249         } else {
1250           _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1251         }
1252       } else {
1253         assert(hr->continuesHumongous(), "only way to get here");
1254         _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1255       }
1256     }
1257     return false;
1258   }
1259 
1260   PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1261     : _hr_printer(hr_printer) { }
1262 };
1263 
1264 void G1CollectedHeap::print_hrs_post_compaction() {
1265   PostCompactionPrinterClosure cl(hr_printer());
1266   heap_region_iterate(&cl);
1267 }
1268 
1269 bool G1CollectedHeap::do_collection(bool explicit_gc,
1270                                     bool clear_all_soft_refs,
1271                                     size_t word_size) {
1272   assert_at_safepoint(true /* should_be_vm_thread */);
1273 
1274   if (GC_locker::check_active_before_gc()) {
1275     return false;
1276   }
1277 
1278   STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1279   gc_timer->register_gc_start();
1280 
1281   SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1282   gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1283 
1284   SvcGCMarker sgcm(SvcGCMarker::FULL);
1285   ResourceMark rm;
1286 
1287   print_heap_before_gc();
1288   trace_heap_before_gc(gc_tracer);
1289 
1290   size_t metadata_prev_used = MetaspaceAux::used_bytes();
1291 
1292   verify_region_sets_optional();
1293 
1294   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1295                            collector_policy()->should_clear_all_soft_refs();
1296 
1297   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1298 
1299   {
1300     IsGCActiveMark x;
1301 
1302     // Timing
1303     assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1304     gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1305     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1306 
1307     {
1308       GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1309       TraceCollectorStats tcs(g1mm()->full_collection_counters());
1310       TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1311 
1312       double start = os::elapsedTime();
1313       g1_policy()->record_full_collection_start();
1314 
1315       // Note: When we have a more flexible GC logging framework that
1316       // allows us to add optional attributes to a GC log record we
1317       // could consider timing and reporting how long we wait in the
1318       // following two methods.
1319       wait_while_free_regions_coming();
1320       // If we start the compaction before the CM threads finish
1321       // scanning the root regions we might trip them over as we'll
1322       // be moving objects / updating references. So let's wait until
1323       // they are done. By telling them to abort, they should complete
1324       // early.
1325       _cm->root_regions()->abort();
1326       _cm->root_regions()->wait_until_scan_finished();
1327       append_secondary_free_list_if_not_empty_with_lock();
1328 
1329       gc_prologue(true);
1330       increment_total_collections(true /* full gc */);
1331       increment_old_marking_cycles_started();
1332 
1333       assert(used() == recalculate_used(), "Should be equal");
1334 
1335       verify_before_gc();
1336 
1337       check_bitmaps("Full GC Start");
1338       pre_full_gc_dump(gc_timer);
1339 
1340       COMPILER2_PRESENT(DerivedPointerTable::clear());
1341 
1342       // Disable discovery and empty the discovered lists
1343       // for the CM ref processor.
1344       ref_processor_cm()->disable_discovery();
1345       ref_processor_cm()->abandon_partial_discovery();
1346       ref_processor_cm()->verify_no_references_recorded();
1347 
1348       // Abandon current iterations of concurrent marking and concurrent
1349       // refinement, if any are in progress. We have to do this before
1350       // wait_until_scan_finished() below.
1351       concurrent_mark()->abort();
1352 
1353       // Make sure we'll choose a new allocation region afterwards.
1354       release_mutator_alloc_region();
1355       abandon_gc_alloc_regions();
1356       g1_rem_set()->cleanupHRRS();
1357 
1358       // We should call this after we retire any currently active alloc
1359       // regions so that all the ALLOC / RETIRE events are generated
1360       // before the start GC event.
1361       _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1362 
1363       // We may have added regions to the current incremental collection
1364       // set between the last GC or pause and now. We need to clear the
1365       // incremental collection set and then start rebuilding it afresh
1366       // after this full GC.
1367       abandon_collection_set(g1_policy()->inc_cset_head());
1368       g1_policy()->clear_incremental_cset();
1369       g1_policy()->stop_incremental_cset_building();
1370 
1371       tear_down_region_sets(false /* free_list_only */);
1372       g1_policy()->set_gcs_are_young(true);
1373 
1374       // See the comments in g1CollectedHeap.hpp and
1375       // G1CollectedHeap::ref_processing_init() about
1376       // how reference processing currently works in G1.
1377 
1378       // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1379       ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1380 
1381       // Temporarily clear the STW ref processor's _is_alive_non_header field.
1382       ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1383 
1384       ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1385       ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1386 
1387       // Do collection work
1388       {
1389         HandleMark hm;  // Discard invalid handles created during gc
1390         G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1391       }
1392 
1393       assert(free_regions() == 0, "we should not have added any free regions");
1394       rebuild_region_sets(false /* free_list_only */);
1395 
1396       // Enqueue any discovered reference objects that have
1397       // not been removed from the discovered lists.
1398       ref_processor_stw()->enqueue_discovered_references();
1399 
1400       COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1401 
1402       MemoryService::track_memory_usage();
1403 
1404       assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1405       ref_processor_stw()->verify_no_references_recorded();
1406 
1407       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1408       ClassLoaderDataGraph::purge();
1409       MetaspaceAux::verify_metrics();
1410 
1411       // Note: since we've just done a full GC, concurrent
1412       // marking is no longer active. Therefore we need not
1413       // re-enable reference discovery for the CM ref processor.
1414       // That will be done at the start of the next marking cycle.
1415       assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1416       ref_processor_cm()->verify_no_references_recorded();
1417 
1418       reset_gc_time_stamp();
1419       // Since everything potentially moved, we will clear all remembered
1420       // sets, and clear all cards.  Later we will rebuild remembered
1421       // sets. We will also reset the GC time stamps of the regions.
1422       clear_rsets_post_compaction();
1423       check_gc_time_stamps();
1424 
1425       // Resize the heap if necessary.
1426       resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1427 
1428       if (_hr_printer.is_active()) {
1429         // We should do this after we potentially resize the heap so
1430         // that all the COMMIT / UNCOMMIT events are generated before
1431         // the end GC event.
1432 
1433         print_hrs_post_compaction();
1434         _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1435       }
1436 
1437       G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1438       if (hot_card_cache->use_cache()) {
1439         hot_card_cache->reset_card_counts();
1440         hot_card_cache->reset_hot_cache();
1441       }
1442 
1443       // Rebuild remembered sets of all regions.
1444       if (G1CollectedHeap::use_parallel_gc_threads()) {
1445         uint n_workers =
1446           AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1447                                                   workers()->active_workers(),
1448                                                   Threads::number_of_non_daemon_threads());
1449         assert(UseDynamicNumberOfGCThreads ||
1450                n_workers == workers()->total_workers(),
1451                "If not dynamic should be using all the  workers");
1452         workers()->set_active_workers(n_workers);
1453         // Set parallel threads in the heap (_n_par_threads) only
1454         // before a parallel phase and always reset it to 0 after
1455         // the phase so that the number of parallel threads does
1456         // no get carried forward to a serial phase where there
1457         // may be code that is "possibly_parallel".
1458         set_par_threads(n_workers);
1459 
1460         ParRebuildRSTask rebuild_rs_task(this);
1461         assert(check_heap_region_claim_values(
1462                HeapRegion::InitialClaimValue), "sanity check");
1463         assert(UseDynamicNumberOfGCThreads ||
1464                workers()->active_workers() == workers()->total_workers(),
1465                "Unless dynamic should use total workers");
1466         // Use the most recent number of  active workers
1467         assert(workers()->active_workers() > 0,
1468                "Active workers not properly set");
1469         set_par_threads(workers()->active_workers());
1470         workers()->run_task(&rebuild_rs_task);
1471         set_par_threads(0);
1472         assert(check_heap_region_claim_values(
1473                HeapRegion::RebuildRSClaimValue), "sanity check");
1474         reset_heap_region_claim_values();
1475       } else {
1476         RebuildRSOutOfRegionClosure rebuild_rs(this);
1477         heap_region_iterate(&rebuild_rs);
1478       }
1479 
1480       // Rebuild the strong code root lists for each region
1481       rebuild_strong_code_roots();
1482 
1483       if (true) { // FIXME
1484         MetaspaceGC::compute_new_size();
1485       }
1486 
1487 #ifdef TRACESPINNING
1488       ParallelTaskTerminator::print_termination_counts();
1489 #endif
1490 
1491       // Discard all rset updates
1492       JavaThread::dirty_card_queue_set().abandon_logs();
1493       assert(!G1DeferredRSUpdate
1494              || (G1DeferredRSUpdate &&
1495                 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1496 
1497       _young_list->reset_sampled_info();
1498       // At this point there should be no regions in the
1499       // entire heap tagged as young.
1500       assert(check_young_list_empty(true /* check_heap */),
1501              "young list should be empty at this point");
1502 
1503       // Update the number of full collections that have been completed.
1504       increment_old_marking_cycles_completed(false /* concurrent */);
1505 
1506       _hrs.verify_optional();
1507       verify_region_sets_optional();
1508 
1509       verify_after_gc();
1510 
1511       // Clear the previous marking bitmap, if needed for bitmap verification.
1512       // Note we cannot do this when we clear the next marking bitmap in
1513       // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1514       // objects marked during a full GC against the previous bitmap.
1515       // But we need to clear it before calling check_bitmaps below since
1516       // the full GC has compacted objects and updated TAMS but not updated
1517       // the prev bitmap.
1518       if (G1VerifyBitmaps) {
1519         ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1520       }
1521       check_bitmaps("Full GC End");
1522 
1523       // Start a new incremental collection set for the next pause
1524       assert(g1_policy()->collection_set() == NULL, "must be");
1525       g1_policy()->start_incremental_cset_building();
1526 
1527       clear_cset_fast_test();
1528 
1529       init_mutator_alloc_region();
1530 
1531       double end = os::elapsedTime();
1532       g1_policy()->record_full_collection_end();
1533 
1534       if (G1Log::fine()) {
1535         g1_policy()->print_heap_transition();
1536       }
1537 
1538       // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1539       // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1540       // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1541       // before any GC notifications are raised.
1542       g1mm()->update_sizes();
1543 
1544       gc_epilogue(true);
1545     }
1546 
1547     if (G1Log::finer()) {
1548       g1_policy()->print_detailed_heap_transition(true /* full */);
1549     }
1550 
1551     print_heap_after_gc();
1552     trace_heap_after_gc(gc_tracer);
1553 
1554     post_full_gc_dump(gc_timer);
1555 
1556     gc_timer->register_gc_end();
1557     gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1558   }
1559 
1560   return true;
1561 }
1562 
1563 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1564   // do_collection() will return whether it succeeded in performing
1565   // the GC. Currently, there is no facility on the
1566   // do_full_collection() API to notify the caller than the collection
1567   // did not succeed (e.g., because it was locked out by the GC
1568   // locker). So, right now, we'll ignore the return value.
1569   bool dummy = do_collection(true,                /* explicit_gc */
1570                              clear_all_soft_refs,
1571                              0                    /* word_size */);
1572 }
1573 
1574 // This code is mostly copied from TenuredGeneration.
1575 void
1576 G1CollectedHeap::
1577 resize_if_necessary_after_full_collection(size_t word_size) {
1578   // Include the current allocation, if any, and bytes that will be
1579   // pre-allocated to support collections, as "used".
1580   const size_t used_after_gc = used();
1581   const size_t capacity_after_gc = capacity();
1582   const size_t free_after_gc = capacity_after_gc - used_after_gc;
1583 
1584   // This is enforced in arguments.cpp.
1585   assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1586          "otherwise the code below doesn't make sense");
1587 
1588   // We don't have floating point command-line arguments
1589   const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1590   const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1591   const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1592   const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1593 
1594   const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1595   const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1596 
1597   // We have to be careful here as these two calculations can overflow
1598   // 32-bit size_t's.
1599   double used_after_gc_d = (double) used_after_gc;
1600   double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1601   double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1602 
1603   // Let's make sure that they are both under the max heap size, which
1604   // by default will make them fit into a size_t.
1605   double desired_capacity_upper_bound = (double) max_heap_size;
1606   minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1607                                     desired_capacity_upper_bound);
1608   maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1609                                     desired_capacity_upper_bound);
1610 
1611   // We can now safely turn them into size_t's.
1612   size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1613   size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1614 
1615   // This assert only makes sense here, before we adjust them
1616   // with respect to the min and max heap size.
1617   assert(minimum_desired_capacity <= maximum_desired_capacity,
1618          err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1619                  "maximum_desired_capacity = "SIZE_FORMAT,
1620                  minimum_desired_capacity, maximum_desired_capacity));
1621 
1622   // Should not be greater than the heap max size. No need to adjust
1623   // it with respect to the heap min size as it's a lower bound (i.e.,
1624   // we'll try to make the capacity larger than it, not smaller).
1625   minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1626   // Should not be less than the heap min size. No need to adjust it
1627   // with respect to the heap max size as it's an upper bound (i.e.,
1628   // we'll try to make the capacity smaller than it, not greater).
1629   maximum_desired_capacity =  MAX2(maximum_desired_capacity, min_heap_size);
1630 
1631   if (capacity_after_gc < minimum_desired_capacity) {
1632     // Don't expand unless it's significant
1633     size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1634     ergo_verbose4(ErgoHeapSizing,
1635                   "attempt heap expansion",
1636                   ergo_format_reason("capacity lower than "
1637                                      "min desired capacity after Full GC")
1638                   ergo_format_byte("capacity")
1639                   ergo_format_byte("occupancy")
1640                   ergo_format_byte_perc("min desired capacity"),
1641                   capacity_after_gc, used_after_gc,
1642                   minimum_desired_capacity, (double) MinHeapFreeRatio);
1643     expand(expand_bytes);
1644 
1645     // No expansion, now see if we want to shrink
1646   } else if (capacity_after_gc > maximum_desired_capacity) {
1647     // Capacity too large, compute shrinking size
1648     size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1649     ergo_verbose4(ErgoHeapSizing,
1650                   "attempt heap shrinking",
1651                   ergo_format_reason("capacity higher than "
1652                                      "max desired capacity after Full GC")
1653                   ergo_format_byte("capacity")
1654                   ergo_format_byte("occupancy")
1655                   ergo_format_byte_perc("max desired capacity"),
1656                   capacity_after_gc, used_after_gc,
1657                   maximum_desired_capacity, (double) MaxHeapFreeRatio);
1658     shrink(shrink_bytes);
1659   }
1660 }
1661 
1662 
1663 HeapWord*
1664 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1665                                            bool* succeeded) {
1666   assert_at_safepoint(true /* should_be_vm_thread */);
1667 
1668   *succeeded = true;
1669   // Let's attempt the allocation first.
1670   HeapWord* result =
1671     attempt_allocation_at_safepoint(word_size,
1672                                  false /* expect_null_mutator_alloc_region */);
1673   if (result != NULL) {
1674     assert(*succeeded, "sanity");
1675     return result;
1676   }
1677 
1678   // In a G1 heap, we're supposed to keep allocation from failing by
1679   // incremental pauses.  Therefore, at least for now, we'll favor
1680   // expansion over collection.  (This might change in the future if we can
1681   // do something smarter than full collection to satisfy a failed alloc.)
1682   result = expand_and_allocate(word_size);
1683   if (result != NULL) {
1684     assert(*succeeded, "sanity");
1685     return result;
1686   }
1687 
1688   // Expansion didn't work, we'll try to do a Full GC.
1689   bool gc_succeeded = do_collection(false, /* explicit_gc */
1690                                     false, /* clear_all_soft_refs */
1691                                     word_size);
1692   if (!gc_succeeded) {
1693     *succeeded = false;
1694     return NULL;
1695   }
1696 
1697   // Retry the allocation
1698   result = attempt_allocation_at_safepoint(word_size,
1699                                   true /* expect_null_mutator_alloc_region */);
1700   if (result != NULL) {
1701     assert(*succeeded, "sanity");
1702     return result;
1703   }
1704 
1705   // Then, try a Full GC that will collect all soft references.
1706   gc_succeeded = do_collection(false, /* explicit_gc */
1707                                true,  /* clear_all_soft_refs */
1708                                word_size);
1709   if (!gc_succeeded) {
1710     *succeeded = false;
1711     return NULL;
1712   }
1713 
1714   // Retry the allocation once more
1715   result = attempt_allocation_at_safepoint(word_size,
1716                                   true /* expect_null_mutator_alloc_region */);
1717   if (result != NULL) {
1718     assert(*succeeded, "sanity");
1719     return result;
1720   }
1721 
1722   assert(!collector_policy()->should_clear_all_soft_refs(),
1723          "Flag should have been handled and cleared prior to this point");
1724 
1725   // What else?  We might try synchronous finalization later.  If the total
1726   // space available is large enough for the allocation, then a more
1727   // complete compaction phase than we've tried so far might be
1728   // appropriate.
1729   assert(*succeeded, "sanity");
1730   return NULL;
1731 }
1732 
1733 // Attempting to expand the heap sufficiently
1734 // to support an allocation of the given "word_size".  If
1735 // successful, perform the allocation and return the address of the
1736 // allocated block, or else "NULL".
1737 
1738 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1739   assert_at_safepoint(true /* should_be_vm_thread */);
1740 
1741   verify_region_sets_optional();
1742 
1743   size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1744   ergo_verbose1(ErgoHeapSizing,
1745                 "attempt heap expansion",
1746                 ergo_format_reason("allocation request failed")
1747                 ergo_format_byte("allocation request"),
1748                 word_size * HeapWordSize);
1749   if (expand(expand_bytes)) {
1750     _hrs.verify_optional();
1751     verify_region_sets_optional();
1752     return attempt_allocation_at_safepoint(word_size,
1753                                  false /* expect_null_mutator_alloc_region */);
1754   }
1755   return NULL;
1756 }
1757 
1758 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1759                                              HeapWord* new_end) {
1760   assert(old_end != new_end, "don't call this otherwise");
1761   assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1762 
1763   // Update the committed mem region.
1764   _g1_committed.set_end(new_end);
1765   // Tell the card table about the update.
1766   Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1767   // Tell the BOT about the update.
1768   _bot_shared->resize(_g1_committed.word_size());
1769   // Tell the hot card cache about the update
1770   _cg1r->hot_card_cache()->resize_card_counts(capacity());
1771 }
1772 
1773 bool G1CollectedHeap::expand(size_t expand_bytes) {
1774   size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1775   aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1776                                        HeapRegion::GrainBytes);
1777   ergo_verbose2(ErgoHeapSizing,
1778                 "expand the heap",
1779                 ergo_format_byte("requested expansion amount")
1780                 ergo_format_byte("attempted expansion amount"),
1781                 expand_bytes, aligned_expand_bytes);
1782 
1783   if (_g1_storage.uncommitted_size() == 0) {
1784     ergo_verbose0(ErgoHeapSizing,
1785                       "did not expand the heap",
1786                       ergo_format_reason("heap already fully expanded"));
1787     return false;
1788   }
1789 
1790   // First commit the memory.
1791   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1792   bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1793   if (successful) {
1794     // Then propagate this update to the necessary data structures.
1795     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1796     update_committed_space(old_end, new_end);
1797 
1798     FreeRegionList expansion_list("Local Expansion List");
1799     MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1800     assert(mr.start() == old_end, "post-condition");
1801     // mr might be a smaller region than what was requested if
1802     // expand_by() was unable to allocate the HeapRegion instances
1803     assert(mr.end() <= new_end, "post-condition");
1804 
1805     size_t actual_expand_bytes = mr.byte_size();
1806     assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1807     assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1808            "post-condition");
1809     if (actual_expand_bytes < aligned_expand_bytes) {
1810       // We could not expand _hrs to the desired size. In this case we
1811       // need to shrink the committed space accordingly.
1812       assert(mr.end() < new_end, "invariant");
1813 
1814       size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1815       // First uncommit the memory.
1816       _g1_storage.shrink_by(diff_bytes);
1817       // Then propagate this update to the necessary data structures.
1818       update_committed_space(new_end, mr.end());
1819     }
1820     _free_list.add_as_tail(&expansion_list);
1821 
1822     if (_hr_printer.is_active()) {
1823       HeapWord* curr = mr.start();
1824       while (curr < mr.end()) {
1825         HeapWord* curr_end = curr + HeapRegion::GrainWords;
1826         _hr_printer.commit(curr, curr_end);
1827         curr = curr_end;
1828       }
1829       assert(curr == mr.end(), "post-condition");
1830     }
1831     g1_policy()->record_new_heap_size(n_regions());
1832   } else {
1833     ergo_verbose0(ErgoHeapSizing,
1834                   "did not expand the heap",
1835                   ergo_format_reason("heap expansion operation failed"));
1836     // The expansion of the virtual storage space was unsuccessful.
1837     // Let's see if it was because we ran out of swap.
1838     if (G1ExitOnExpansionFailure &&
1839         _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1840       // We had head room...
1841       vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1842     }
1843   }
1844   return successful;
1845 }
1846 
1847 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1848   size_t aligned_shrink_bytes =
1849     ReservedSpace::page_align_size_down(shrink_bytes);
1850   aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1851                                          HeapRegion::GrainBytes);
1852   uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1853 
1854   uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1855   HeapWord* old_end = (HeapWord*) _g1_storage.high();
1856   size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1857 
1858   ergo_verbose3(ErgoHeapSizing,
1859                 "shrink the heap",
1860                 ergo_format_byte("requested shrinking amount")
1861                 ergo_format_byte("aligned shrinking amount")
1862                 ergo_format_byte("attempted shrinking amount"),
1863                 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1864   if (num_regions_removed > 0) {
1865     _g1_storage.shrink_by(shrunk_bytes);
1866     HeapWord* new_end = (HeapWord*) _g1_storage.high();
1867 
1868     if (_hr_printer.is_active()) {
1869       HeapWord* curr = old_end;
1870       while (curr > new_end) {
1871         HeapWord* curr_end = curr;
1872         curr -= HeapRegion::GrainWords;
1873         _hr_printer.uncommit(curr, curr_end);
1874       }
1875     }
1876 
1877     _expansion_regions += num_regions_removed;
1878     update_committed_space(old_end, new_end);
1879     HeapRegionRemSet::shrink_heap(n_regions());
1880     g1_policy()->record_new_heap_size(n_regions());
1881   } else {
1882     ergo_verbose0(ErgoHeapSizing,
1883                   "did not shrink the heap",
1884                   ergo_format_reason("heap shrinking operation failed"));
1885   }
1886 }
1887 
1888 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1889   verify_region_sets_optional();
1890 
1891   // We should only reach here at the end of a Full GC which means we
1892   // should not not be holding to any GC alloc regions. The method
1893   // below will make sure of that and do any remaining clean up.
1894   abandon_gc_alloc_regions();
1895 
1896   // Instead of tearing down / rebuilding the free lists here, we
1897   // could instead use the remove_all_pending() method on free_list to
1898   // remove only the ones that we need to remove.
1899   tear_down_region_sets(true /* free_list_only */);
1900   shrink_helper(shrink_bytes);
1901   rebuild_region_sets(true /* free_list_only */);
1902 
1903   _hrs.verify_optional();
1904   verify_region_sets_optional();
1905 }
1906 
1907 // Public methods.
1908 
1909 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1910 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1911 #endif // _MSC_VER
1912 
1913 
1914 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1915   SharedHeap(policy_),
1916   _g1_policy(policy_),
1917   _dirty_card_queue_set(false),
1918   _into_cset_dirty_card_queue_set(false),
1919   _is_alive_closure_cm(this),
1920   _is_alive_closure_stw(this),
1921   _ref_processor_cm(NULL),
1922   _ref_processor_stw(NULL),
1923   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1924   _bot_shared(NULL),
1925   _evac_failure_scan_stack(NULL),
1926   _mark_in_progress(false),
1927   _cg1r(NULL), _summary_bytes_used(0),
1928   _g1mm(NULL),
1929   _refine_cte_cl(NULL),
1930   _full_collection(false),
1931   _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1932   _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1933   _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1934   _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1935   _free_regions_coming(false),
1936   _young_list(new YoungList(this)),
1937   _gc_time_stamp(0),
1938   _retained_old_gc_alloc_region(NULL),
1939   _survivor_plab_stats(YoungPLABSize, PLABWeight),
1940   _old_plab_stats(OldPLABSize, PLABWeight),
1941   _expand_heap_after_alloc_failure(true),
1942   _surviving_young_words(NULL),
1943   _old_marking_cycles_started(0),
1944   _old_marking_cycles_completed(0),
1945   _concurrent_cycle_started(false),
1946   _in_cset_fast_test(),
1947   _dirty_cards_region_list(NULL),
1948   _worker_cset_start_region(NULL),
1949   _worker_cset_start_region_time_stamp(NULL),
1950   _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1951   _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1952   _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1953   _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1954 
1955   _g1h = this;
1956   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1957     vm_exit_during_initialization("Failed necessary allocation.");
1958   }
1959 
1960   _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1961 
1962   int n_queues = MAX2((int)ParallelGCThreads, 1);
1963   _task_queues = new RefToScanQueueSet(n_queues);
1964 
1965   uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1966   assert(n_rem_sets > 0, "Invariant.");
1967 
1968   _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1969   _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1970   _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1971 
1972   for (int i = 0; i < n_queues; i++) {
1973     RefToScanQueue* q = new RefToScanQueue();
1974     q->initialize();
1975     _task_queues->register_queue(i, q);
1976     ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1977   }
1978   clear_cset_start_regions();
1979 
1980   // Initialize the G1EvacuationFailureALot counters and flags.
1981   NOT_PRODUCT(reset_evacuation_should_fail();)
1982 
1983   guarantee(_task_queues != NULL, "task_queues allocation failure.");
1984 }
1985 
1986 jint G1CollectedHeap::initialize() {
1987   CollectedHeap::pre_initialize();
1988   os::enable_vtime();
1989 
1990   G1Log::init();
1991 
1992   // Necessary to satisfy locking discipline assertions.
1993 
1994   MutexLocker x(Heap_lock);
1995 
1996   // We have to initialize the printer before committing the heap, as
1997   // it will be used then.
1998   _hr_printer.set_active(G1PrintHeapRegions);
1999 
2000   // While there are no constraints in the GC code that HeapWordSize
2001   // be any particular value, there are multiple other areas in the
2002   // system which believe this to be true (e.g. oop->object_size in some
2003   // cases incorrectly returns the size in wordSize units rather than
2004   // HeapWordSize).
2005   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2006 
2007   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2008   size_t max_byte_size = collector_policy()->max_heap_byte_size();
2009   size_t heap_alignment = collector_policy()->heap_alignment();
2010 
2011   // Ensure that the sizes are properly aligned.
2012   Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2013   Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2014   Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2015 
2016   _refine_cte_cl = new RefineCardTableEntryClosure();
2017 
2018   _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2019 
2020   // Reserve the maximum.
2021 
2022   // When compressed oops are enabled, the preferred heap base
2023   // is calculated by subtracting the requested size from the
2024   // 32Gb boundary and using the result as the base address for
2025   // heap reservation. If the requested size is not aligned to
2026   // HeapRegion::GrainBytes (i.e. the alignment that is passed
2027   // into the ReservedHeapSpace constructor) then the actual
2028   // base of the reserved heap may end up differing from the
2029   // address that was requested (i.e. the preferred heap base).
2030   // If this happens then we could end up using a non-optimal
2031   // compressed oops mode.
2032 
2033   ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2034                                                  heap_alignment);
2035 
2036   // It is important to do this in a way such that concurrent readers can't
2037   // temporarily think something is in the heap.  (I've actually seen this
2038   // happen in asserts: DLD.)
2039   _reserved.set_word_size(0);
2040   _reserved.set_start((HeapWord*)heap_rs.base());
2041   _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2042 
2043   _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2044 
2045   // Create the gen rem set (and barrier set) for the entire reserved region.
2046   _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2047   set_barrier_set(rem_set()->bs());
2048   if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2049     vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2050     return JNI_ENOMEM;
2051   }
2052 
2053   // Also create a G1 rem set.
2054   _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2055 
2056   // Carve out the G1 part of the heap.
2057 
2058   ReservedSpace g1_rs   = heap_rs.first_part(max_byte_size);
2059   _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2060                            g1_rs.size()/HeapWordSize);
2061 
2062   _g1_storage.initialize(g1_rs, 0);
2063   _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2064   _hrs.initialize((HeapWord*) _g1_reserved.start(),
2065                   (HeapWord*) _g1_reserved.end());
2066   assert(_hrs.max_length() == _expansion_regions,
2067          err_msg("max length: %u expansion regions: %u",
2068                  _hrs.max_length(), _expansion_regions));
2069 
2070   // Do later initialization work for concurrent refinement.
2071   _cg1r->init();
2072 
2073   // 6843694 - ensure that the maximum region index can fit
2074   // in the remembered set structures.
2075   const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2076   guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2077 
2078   size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2079   guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2080   guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2081             "too many cards per region");
2082 
2083   FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2084 
2085   _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2086                                              heap_word_size(init_byte_size));
2087 
2088   _g1h = this;
2089 
2090   _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2091 
2092   // Create the ConcurrentMark data structure and thread.
2093   // (Must do this late, so that "max_regions" is defined.)
2094   _cm = new ConcurrentMark(this, heap_rs);
2095   if (_cm == NULL || !_cm->completed_initialization()) {
2096     vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2097     return JNI_ENOMEM;
2098   }
2099   _cmThread = _cm->cmThread();
2100 
2101   // Initialize the from_card cache structure of HeapRegionRemSet.
2102   HeapRegionRemSet::init_heap(max_regions());
2103 
2104   // Now expand into the initial heap size.
2105   if (!expand(init_byte_size)) {
2106     vm_shutdown_during_initialization("Failed to allocate initial heap.");
2107     return JNI_ENOMEM;
2108   }
2109 
2110   // Perform any initialization actions delegated to the policy.
2111   g1_policy()->init();
2112 
2113   JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2114                                                SATB_Q_FL_lock,
2115                                                G1SATBProcessCompletedThreshold,
2116                                                Shared_SATB_Q_lock);
2117 
2118   JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2119                                                 DirtyCardQ_CBL_mon,
2120                                                 DirtyCardQ_FL_lock,
2121                                                 concurrent_g1_refine()->yellow_zone(),
2122                                                 concurrent_g1_refine()->red_zone(),
2123                                                 Shared_DirtyCardQ_lock);
2124 
2125   if (G1DeferredRSUpdate) {
2126     dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2127                                       DirtyCardQ_CBL_mon,
2128                                       DirtyCardQ_FL_lock,
2129                                       -1, // never trigger processing
2130                                       -1, // no limit on length
2131                                       Shared_DirtyCardQ_lock,
2132                                       &JavaThread::dirty_card_queue_set());
2133   }
2134 
2135   // Initialize the card queue set used to hold cards containing
2136   // references into the collection set.
2137   _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2138                                              DirtyCardQ_CBL_mon,
2139                                              DirtyCardQ_FL_lock,
2140                                              -1, // never trigger processing
2141                                              -1, // no limit on length
2142                                              Shared_DirtyCardQ_lock,
2143                                              &JavaThread::dirty_card_queue_set());
2144 
2145   // In case we're keeping closure specialization stats, initialize those
2146   // counts and that mechanism.
2147   SpecializationStats::clear();
2148 
2149   // Here we allocate the dummy full region that is required by the
2150   // G1AllocRegion class. If we don't pass an address in the reserved
2151   // space here, lots of asserts fire.
2152 
2153   HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2154                                              _g1_reserved.start());
2155   // We'll re-use the same region whether the alloc region will
2156   // require BOT updates or not and, if it doesn't, then a non-young
2157   // region will complain that it cannot support allocations without
2158   // BOT updates. So we'll tag the dummy region as young to avoid that.
2159   dummy_region->set_young();
2160   // Make sure it's full.
2161   dummy_region->set_top(dummy_region->end());
2162   G1AllocRegion::setup(this, dummy_region);
2163 
2164   init_mutator_alloc_region();
2165 
2166   // Do create of the monitoring and management support so that
2167   // values in the heap have been properly initialized.
2168   _g1mm = new G1MonitoringSupport(this);
2169 
2170   G1StringDedup::initialize();
2171 
2172   return JNI_OK;
2173 }
2174 
2175 void G1CollectedHeap::stop() {
2176 #if 0
2177   // Stopping concurrent worker threads is currently disabled until
2178   // some bugs in concurrent mark has been resolve. Without fixing
2179   // those bugs first we risk haning during VM exit when trying to
2180   // stop these threads.
2181 
2182   // Abort any ongoing concurrent root region scanning and stop all
2183   // concurrent threads. We do this to make sure these threads do
2184   // not continue to execute and access resources (e.g. gclog_or_tty)
2185   // that are destroyed during shutdown.
2186   _cm->root_regions()->abort();
2187   _cm->root_regions()->wait_until_scan_finished();
2188   stop_conc_gc_threads();
2189 #endif
2190 }
2191 
2192 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2193   return HeapRegion::max_region_size();
2194 }
2195 
2196 void G1CollectedHeap::ref_processing_init() {
2197   // Reference processing in G1 currently works as follows:
2198   //
2199   // * There are two reference processor instances. One is
2200   //   used to record and process discovered references
2201   //   during concurrent marking; the other is used to
2202   //   record and process references during STW pauses
2203   //   (both full and incremental).
2204   // * Both ref processors need to 'span' the entire heap as
2205   //   the regions in the collection set may be dotted around.
2206   //
2207   // * For the concurrent marking ref processor:
2208   //   * Reference discovery is enabled at initial marking.
2209   //   * Reference discovery is disabled and the discovered
2210   //     references processed etc during remarking.
2211   //   * Reference discovery is MT (see below).
2212   //   * Reference discovery requires a barrier (see below).
2213   //   * Reference processing may or may not be MT
2214   //     (depending on the value of ParallelRefProcEnabled
2215   //     and ParallelGCThreads).
2216   //   * A full GC disables reference discovery by the CM
2217   //     ref processor and abandons any entries on it's
2218   //     discovered lists.
2219   //
2220   // * For the STW processor:
2221   //   * Non MT discovery is enabled at the start of a full GC.
2222   //   * Processing and enqueueing during a full GC is non-MT.
2223   //   * During a full GC, references are processed after marking.
2224   //
2225   //   * Discovery (may or may not be MT) is enabled at the start
2226   //     of an incremental evacuation pause.
2227   //   * References are processed near the end of a STW evacuation pause.
2228   //   * For both types of GC:
2229   //     * Discovery is atomic - i.e. not concurrent.
2230   //     * Reference discovery will not need a barrier.
2231 
2232   SharedHeap::ref_processing_init();
2233   MemRegion mr = reserved_region();
2234 
2235   // Concurrent Mark ref processor
2236   _ref_processor_cm =
2237     new ReferenceProcessor(mr,    // span
2238                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2239                                 // mt processing
2240                            (int) ParallelGCThreads,
2241                                 // degree of mt processing
2242                            (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2243                                 // mt discovery
2244                            (int) MAX2(ParallelGCThreads, ConcGCThreads),
2245                                 // degree of mt discovery
2246                            false,
2247                                 // Reference discovery is not atomic
2248                            &_is_alive_closure_cm,
2249                                 // is alive closure
2250                                 // (for efficiency/performance)
2251                            true);
2252                                 // Setting next fields of discovered
2253                                 // lists requires a barrier.
2254 
2255   // STW ref processor
2256   _ref_processor_stw =
2257     new ReferenceProcessor(mr,    // span
2258                            ParallelRefProcEnabled && (ParallelGCThreads > 1),
2259                                 // mt processing
2260                            MAX2((int)ParallelGCThreads, 1),
2261                                 // degree of mt processing
2262                            (ParallelGCThreads > 1),
2263                                 // mt discovery
2264                            MAX2((int)ParallelGCThreads, 1),
2265                                 // degree of mt discovery
2266                            true,
2267                                 // Reference discovery is atomic
2268                            &_is_alive_closure_stw,
2269                                 // is alive closure
2270                                 // (for efficiency/performance)
2271                            false);
2272                                 // Setting next fields of discovered
2273                                 // lists does not require a barrier.
2274 }
2275 
2276 size_t G1CollectedHeap::capacity() const {
2277   return _g1_committed.byte_size();
2278 }
2279 
2280 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2281   assert(!hr->continuesHumongous(), "pre-condition");
2282   hr->reset_gc_time_stamp();
2283   if (hr->startsHumongous()) {
2284     uint first_index = hr->hrs_index() + 1;
2285     uint last_index = hr->last_hc_index();
2286     for (uint i = first_index; i < last_index; i += 1) {
2287       HeapRegion* chr = region_at(i);
2288       assert(chr->continuesHumongous(), "sanity");
2289       chr->reset_gc_time_stamp();
2290     }
2291   }
2292 }
2293 
2294 #ifndef PRODUCT
2295 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2296 private:
2297   unsigned _gc_time_stamp;
2298   bool _failures;
2299 
2300 public:
2301   CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2302     _gc_time_stamp(gc_time_stamp), _failures(false) { }
2303 
2304   virtual bool doHeapRegion(HeapRegion* hr) {
2305     unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2306     if (_gc_time_stamp != region_gc_time_stamp) {
2307       gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2308                              "expected %d", HR_FORMAT_PARAMS(hr),
2309                              region_gc_time_stamp, _gc_time_stamp);
2310       _failures = true;
2311     }
2312     return false;
2313   }
2314 
2315   bool failures() { return _failures; }
2316 };
2317 
2318 void G1CollectedHeap::check_gc_time_stamps() {
2319   CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2320   heap_region_iterate(&cl);
2321   guarantee(!cl.failures(), "all GC time stamps should have been reset");
2322 }
2323 #endif // PRODUCT
2324 
2325 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2326                                                  DirtyCardQueue* into_cset_dcq,
2327                                                  bool concurrent,
2328                                                  uint worker_i) {
2329   // Clean cards in the hot card cache
2330   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2331   hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2332 
2333   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2334   int n_completed_buffers = 0;
2335   while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2336     n_completed_buffers++;
2337   }
2338   g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2339   dcqs.clear_n_completed_buffers();
2340   assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2341 }
2342 
2343 
2344 // Computes the sum of the storage used by the various regions.
2345 
2346 size_t G1CollectedHeap::used() const {
2347   assert(Heap_lock->owner() != NULL,
2348          "Should be owned on this thread's behalf.");
2349   size_t result = _summary_bytes_used;
2350   // Read only once in case it is set to NULL concurrently
2351   HeapRegion* hr = _mutator_alloc_region.get();
2352   if (hr != NULL)
2353     result += hr->used();
2354   return result;
2355 }
2356 
2357 size_t G1CollectedHeap::used_unlocked() const {
2358   size_t result = _summary_bytes_used;
2359   return result;
2360 }
2361 
2362 class SumUsedClosure: public HeapRegionClosure {
2363   size_t _used;
2364 public:
2365   SumUsedClosure() : _used(0) {}
2366   bool doHeapRegion(HeapRegion* r) {
2367     if (!r->continuesHumongous()) {
2368       _used += r->used();
2369     }
2370     return false;
2371   }
2372   size_t result() { return _used; }
2373 };
2374 
2375 size_t G1CollectedHeap::recalculate_used() const {
2376   double recalculate_used_start = os::elapsedTime();
2377 
2378   SumUsedClosure blk;
2379   heap_region_iterate(&blk);
2380 
2381   g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2382   return blk.result();
2383 }
2384 
2385 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2386   switch (cause) {
2387     case GCCause::_gc_locker:               return GCLockerInvokesConcurrent;
2388     case GCCause::_java_lang_system_gc:     return ExplicitGCInvokesConcurrent;
2389     case GCCause::_g1_humongous_allocation: return true;
2390     default:                                return false;
2391   }
2392 }
2393 
2394 #ifndef PRODUCT
2395 void G1CollectedHeap::allocate_dummy_regions() {
2396   // Let's fill up most of the region
2397   size_t word_size = HeapRegion::GrainWords - 1024;
2398   // And as a result the region we'll allocate will be humongous.
2399   guarantee(isHumongous(word_size), "sanity");
2400 
2401   for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2402     // Let's use the existing mechanism for the allocation
2403     HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2404     if (dummy_obj != NULL) {
2405       MemRegion mr(dummy_obj, word_size);
2406       CollectedHeap::fill_with_object(mr);
2407     } else {
2408       // If we can't allocate once, we probably cannot allocate
2409       // again. Let's get out of the loop.
2410       break;
2411     }
2412   }
2413 }
2414 #endif // !PRODUCT
2415 
2416 void G1CollectedHeap::increment_old_marking_cycles_started() {
2417   assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2418     _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2419     err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2420     _old_marking_cycles_started, _old_marking_cycles_completed));
2421 
2422   _old_marking_cycles_started++;
2423 }
2424 
2425 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2426   MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2427 
2428   // We assume that if concurrent == true, then the caller is a
2429   // concurrent thread that was joined the Suspendible Thread
2430   // Set. If there's ever a cheap way to check this, we should add an
2431   // assert here.
2432 
2433   // Given that this method is called at the end of a Full GC or of a
2434   // concurrent cycle, and those can be nested (i.e., a Full GC can
2435   // interrupt a concurrent cycle), the number of full collections
2436   // completed should be either one (in the case where there was no
2437   // nesting) or two (when a Full GC interrupted a concurrent cycle)
2438   // behind the number of full collections started.
2439 
2440   // This is the case for the inner caller, i.e. a Full GC.
2441   assert(concurrent ||
2442          (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2443          (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2444          err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2445                  "is inconsistent with _old_marking_cycles_completed = %u",
2446                  _old_marking_cycles_started, _old_marking_cycles_completed));
2447 
2448   // This is the case for the outer caller, i.e. the concurrent cycle.
2449   assert(!concurrent ||
2450          (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2451          err_msg("for outer caller (concurrent cycle): "
2452                  "_old_marking_cycles_started = %u "
2453                  "is inconsistent with _old_marking_cycles_completed = %u",
2454                  _old_marking_cycles_started, _old_marking_cycles_completed));
2455 
2456   _old_marking_cycles_completed += 1;
2457 
2458   // We need to clear the "in_progress" flag in the CM thread before
2459   // we wake up any waiters (especially when ExplicitInvokesConcurrent
2460   // is set) so that if a waiter requests another System.gc() it doesn't
2461   // incorrectly see that a marking cycle is still in progress.
2462   if (concurrent) {
2463     _cmThread->clear_in_progress();
2464   }
2465 
2466   // This notify_all() will ensure that a thread that called
2467   // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2468   // and it's waiting for a full GC to finish will be woken up. It is
2469   // waiting in VM_G1IncCollectionPause::doit_epilogue().
2470   FullGCCount_lock->notify_all();
2471 }
2472 
2473 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2474   _concurrent_cycle_started = true;
2475   _gc_timer_cm->register_gc_start(start_time);
2476 
2477   _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2478   trace_heap_before_gc(_gc_tracer_cm);
2479 }
2480 
2481 void G1CollectedHeap::register_concurrent_cycle_end() {
2482   if (_concurrent_cycle_started) {
2483     if (_cm->has_aborted()) {
2484       _gc_tracer_cm->report_concurrent_mode_failure();
2485     }
2486 
2487     _gc_timer_cm->register_gc_end();
2488     _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2489 
2490     _concurrent_cycle_started = false;
2491   }
2492 }
2493 
2494 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2495   if (_concurrent_cycle_started) {
2496     trace_heap_after_gc(_gc_tracer_cm);
2497   }
2498 }
2499 
2500 G1YCType G1CollectedHeap::yc_type() {
2501   bool is_young = g1_policy()->gcs_are_young();
2502   bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2503   bool is_during_mark = mark_in_progress();
2504 
2505   if (is_initial_mark) {
2506     return InitialMark;
2507   } else if (is_during_mark) {
2508     return DuringMark;
2509   } else if (is_young) {
2510     return Normal;
2511   } else {
2512     return Mixed;
2513   }
2514 }
2515 
2516 void G1CollectedHeap::collect(GCCause::Cause cause) {
2517   assert_heap_not_locked();
2518 
2519   unsigned int gc_count_before;
2520   unsigned int old_marking_count_before;
2521   bool retry_gc;
2522 
2523   do {
2524     retry_gc = false;
2525 
2526     {
2527       MutexLocker ml(Heap_lock);
2528 
2529       // Read the GC count while holding the Heap_lock
2530       gc_count_before = total_collections();
2531       old_marking_count_before = _old_marking_cycles_started;
2532     }
2533 
2534     if (should_do_concurrent_full_gc(cause)) {
2535       // Schedule an initial-mark evacuation pause that will start a
2536       // concurrent cycle. We're setting word_size to 0 which means that
2537       // we are not requesting a post-GC allocation.
2538       VM_G1IncCollectionPause op(gc_count_before,
2539                                  0,     /* word_size */
2540                                  true,  /* should_initiate_conc_mark */
2541                                  g1_policy()->max_pause_time_ms(),
2542                                  cause);
2543 
2544       VMThread::execute(&op);
2545       if (!op.pause_succeeded()) {
2546         if (old_marking_count_before == _old_marking_cycles_started) {
2547           retry_gc = op.should_retry_gc();
2548         } else {
2549           // A Full GC happened while we were trying to schedule the
2550           // initial-mark GC. No point in starting a new cycle given
2551           // that the whole heap was collected anyway.
2552         }
2553 
2554         if (retry_gc) {
2555           if (GC_locker::is_active_and_needs_gc()) {
2556             GC_locker::stall_until_clear();
2557           }
2558         }
2559       }
2560     } else {
2561       if (cause == GCCause::_gc_locker
2562           DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2563 
2564         // Schedule a standard evacuation pause. We're setting word_size
2565         // to 0 which means that we are not requesting a post-GC allocation.
2566         VM_G1IncCollectionPause op(gc_count_before,
2567                                    0,     /* word_size */
2568                                    false, /* should_initiate_conc_mark */
2569                                    g1_policy()->max_pause_time_ms(),
2570                                    cause);
2571         VMThread::execute(&op);
2572       } else {
2573         // Schedule a Full GC.
2574         VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2575         VMThread::execute(&op);
2576       }
2577     }
2578   } while (retry_gc);
2579 }
2580 
2581 bool G1CollectedHeap::is_in(const void* p) const {
2582   if (_g1_committed.contains(p)) {
2583     // Given that we know that p is in the committed space,
2584     // heap_region_containing_raw() should successfully
2585     // return the containing region.
2586     HeapRegion* hr = heap_region_containing_raw(p);
2587     return hr->is_in(p);
2588   } else {
2589     return false;
2590   }
2591 }
2592 
2593 // Iteration functions.
2594 
2595 // Iterates an OopClosure over all ref-containing fields of objects
2596 // within a HeapRegion.
2597 
2598 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2599   MemRegion _mr;
2600   ExtendedOopClosure* _cl;
2601 public:
2602   IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2603     : _mr(mr), _cl(cl) {}
2604   bool doHeapRegion(HeapRegion* r) {
2605     if (!r->continuesHumongous()) {
2606       r->oop_iterate(_cl);
2607     }
2608     return false;
2609   }
2610 };
2611 
2612 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2613   IterateOopClosureRegionClosure blk(_g1_committed, cl);
2614   heap_region_iterate(&blk);
2615 }
2616 
2617 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2618   IterateOopClosureRegionClosure blk(mr, cl);
2619   heap_region_iterate(&blk);
2620 }
2621 
2622 // Iterates an ObjectClosure over all objects within a HeapRegion.
2623 
2624 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2625   ObjectClosure* _cl;
2626 public:
2627   IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2628   bool doHeapRegion(HeapRegion* r) {
2629     if (! r->continuesHumongous()) {
2630       r->object_iterate(_cl);
2631     }
2632     return false;
2633   }
2634 };
2635 
2636 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2637   IterateObjectClosureRegionClosure blk(cl);
2638   heap_region_iterate(&blk);
2639 }
2640 
2641 // Calls a SpaceClosure on a HeapRegion.
2642 
2643 class SpaceClosureRegionClosure: public HeapRegionClosure {
2644   SpaceClosure* _cl;
2645 public:
2646   SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2647   bool doHeapRegion(HeapRegion* r) {
2648     _cl->do_space(r);
2649     return false;
2650   }
2651 };
2652 
2653 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2654   SpaceClosureRegionClosure blk(cl);
2655   heap_region_iterate(&blk);
2656 }
2657 
2658 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2659   _hrs.iterate(cl);
2660 }
2661 
2662 void
2663 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2664                                                  uint worker_id,
2665                                                  uint no_of_par_workers,
2666                                                  jint claim_value) {
2667   const uint regions = n_regions();
2668   const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2669                              no_of_par_workers :
2670                              1);
2671   assert(UseDynamicNumberOfGCThreads ||
2672          no_of_par_workers == workers()->total_workers(),
2673          "Non dynamic should use fixed number of workers");
2674   // try to spread out the starting points of the workers
2675   const HeapRegion* start_hr =
2676                         start_region_for_worker(worker_id, no_of_par_workers);
2677   const uint start_index = start_hr->hrs_index();
2678 
2679   // each worker will actually look at all regions
2680   for (uint count = 0; count < regions; ++count) {
2681     const uint index = (start_index + count) % regions;
2682     assert(0 <= index && index < regions, "sanity");
2683     HeapRegion* r = region_at(index);
2684     // we'll ignore "continues humongous" regions (we'll process them
2685     // when we come across their corresponding "start humongous"
2686     // region) and regions already claimed
2687     if (r->claim_value() == claim_value || r->continuesHumongous()) {
2688       continue;
2689     }
2690     // OK, try to claim it
2691     if (r->claimHeapRegion(claim_value)) {
2692       // success!
2693       assert(!r->continuesHumongous(), "sanity");
2694       if (r->startsHumongous()) {
2695         // If the region is "starts humongous" we'll iterate over its
2696         // "continues humongous" first; in fact we'll do them
2697         // first. The order is important. In on case, calling the
2698         // closure on the "starts humongous" region might de-allocate
2699         // and clear all its "continues humongous" regions and, as a
2700         // result, we might end up processing them twice. So, we'll do
2701         // them first (notice: most closures will ignore them anyway) and
2702         // then we'll do the "starts humongous" region.
2703         for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2704           HeapRegion* chr = region_at(ch_index);
2705 
2706           // if the region has already been claimed or it's not
2707           // "continues humongous" we're done
2708           if (chr->claim_value() == claim_value ||
2709               !chr->continuesHumongous()) {
2710             break;
2711           }
2712 
2713           // No one should have claimed it directly. We can given
2714           // that we claimed its "starts humongous" region.
2715           assert(chr->claim_value() != claim_value, "sanity");
2716           assert(chr->humongous_start_region() == r, "sanity");
2717 
2718           if (chr->claimHeapRegion(claim_value)) {
2719             // we should always be able to claim it; no one else should
2720             // be trying to claim this region
2721 
2722             bool res2 = cl->doHeapRegion(chr);
2723             assert(!res2, "Should not abort");
2724 
2725             // Right now, this holds (i.e., no closure that actually
2726             // does something with "continues humongous" regions
2727             // clears them). We might have to weaken it in the future,
2728             // but let's leave these two asserts here for extra safety.
2729             assert(chr->continuesHumongous(), "should still be the case");
2730             assert(chr->humongous_start_region() == r, "sanity");
2731           } else {
2732             guarantee(false, "we should not reach here");
2733           }
2734         }
2735       }
2736 
2737       assert(!r->continuesHumongous(), "sanity");
2738       bool res = cl->doHeapRegion(r);
2739       assert(!res, "Should not abort");
2740     }
2741   }
2742 }
2743 
2744 class ResetClaimValuesClosure: public HeapRegionClosure {
2745 public:
2746   bool doHeapRegion(HeapRegion* r) {
2747     r->set_claim_value(HeapRegion::InitialClaimValue);
2748     return false;
2749   }
2750 };
2751 
2752 void G1CollectedHeap::reset_heap_region_claim_values() {
2753   ResetClaimValuesClosure blk;
2754   heap_region_iterate(&blk);
2755 }
2756 
2757 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2758   ResetClaimValuesClosure blk;
2759   collection_set_iterate(&blk);
2760 }
2761 
2762 #ifdef ASSERT
2763 // This checks whether all regions in the heap have the correct claim
2764 // value. I also piggy-backed on this a check to ensure that the
2765 // humongous_start_region() information on "continues humongous"
2766 // regions is correct.
2767 
2768 class CheckClaimValuesClosure : public HeapRegionClosure {
2769 private:
2770   jint _claim_value;
2771   uint _failures;
2772   HeapRegion* _sh_region;
2773 
2774 public:
2775   CheckClaimValuesClosure(jint claim_value) :
2776     _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2777   bool doHeapRegion(HeapRegion* r) {
2778     if (r->claim_value() != _claim_value) {
2779       gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2780                              "claim value = %d, should be %d",
2781                              HR_FORMAT_PARAMS(r),
2782                              r->claim_value(), _claim_value);
2783       ++_failures;
2784     }
2785     if (!r->isHumongous()) {
2786       _sh_region = NULL;
2787     } else if (r->startsHumongous()) {
2788       _sh_region = r;
2789     } else if (r->continuesHumongous()) {
2790       if (r->humongous_start_region() != _sh_region) {
2791         gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2792                                "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2793                                HR_FORMAT_PARAMS(r),
2794                                r->humongous_start_region(),
2795                                _sh_region);
2796         ++_failures;
2797       }
2798     }
2799     return false;
2800   }
2801   uint failures() { return _failures; }
2802 };
2803 
2804 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2805   CheckClaimValuesClosure cl(claim_value);
2806   heap_region_iterate(&cl);
2807   return cl.failures() == 0;
2808 }
2809 
2810 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2811 private:
2812   jint _claim_value;
2813   uint _failures;
2814 
2815 public:
2816   CheckClaimValuesInCSetHRClosure(jint claim_value) :
2817     _claim_value(claim_value), _failures(0) { }
2818 
2819   uint failures() { return _failures; }
2820 
2821   bool doHeapRegion(HeapRegion* hr) {
2822     assert(hr->in_collection_set(), "how?");
2823     assert(!hr->isHumongous(), "H-region in CSet");
2824     if (hr->claim_value() != _claim_value) {
2825       gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2826                              "claim value = %d, should be %d",
2827                              HR_FORMAT_PARAMS(hr),
2828                              hr->claim_value(), _claim_value);
2829       _failures += 1;
2830     }
2831     return false;
2832   }
2833 };
2834 
2835 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2836   CheckClaimValuesInCSetHRClosure cl(claim_value);
2837   collection_set_iterate(&cl);
2838   return cl.failures() == 0;
2839 }
2840 #endif // ASSERT
2841 
2842 // Clear the cached CSet starting regions and (more importantly)
2843 // the time stamps. Called when we reset the GC time stamp.
2844 void G1CollectedHeap::clear_cset_start_regions() {
2845   assert(_worker_cset_start_region != NULL, "sanity");
2846   assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2847 
2848   int n_queues = MAX2((int)ParallelGCThreads, 1);
2849   for (int i = 0; i < n_queues; i++) {
2850     _worker_cset_start_region[i] = NULL;
2851     _worker_cset_start_region_time_stamp[i] = 0;
2852   }
2853 }
2854 
2855 // Given the id of a worker, obtain or calculate a suitable
2856 // starting region for iterating over the current collection set.
2857 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2858   assert(get_gc_time_stamp() > 0, "should have been updated by now");
2859 
2860   HeapRegion* result = NULL;
2861   unsigned gc_time_stamp = get_gc_time_stamp();
2862 
2863   if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2864     // Cached starting region for current worker was set
2865     // during the current pause - so it's valid.
2866     // Note: the cached starting heap region may be NULL
2867     // (when the collection set is empty).
2868     result = _worker_cset_start_region[worker_i];
2869     assert(result == NULL || result->in_collection_set(), "sanity");
2870     return result;
2871   }
2872 
2873   // The cached entry was not valid so let's calculate
2874   // a suitable starting heap region for this worker.
2875 
2876   // We want the parallel threads to start their collection
2877   // set iteration at different collection set regions to
2878   // avoid contention.
2879   // If we have:
2880   //          n collection set regions
2881   //          p threads
2882   // Then thread t will start at region floor ((t * n) / p)
2883 
2884   result = g1_policy()->collection_set();
2885   if (G1CollectedHeap::use_parallel_gc_threads()) {
2886     uint cs_size = g1_policy()->cset_region_length();
2887     uint active_workers = workers()->active_workers();
2888     assert(UseDynamicNumberOfGCThreads ||
2889              active_workers == workers()->total_workers(),
2890              "Unless dynamic should use total workers");
2891 
2892     uint end_ind   = (cs_size * worker_i) / active_workers;
2893     uint start_ind = 0;
2894 
2895     if (worker_i > 0 &&
2896         _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2897       // Previous workers starting region is valid
2898       // so let's iterate from there
2899       start_ind = (cs_size * (worker_i - 1)) / active_workers;
2900       result = _worker_cset_start_region[worker_i - 1];
2901     }
2902 
2903     for (uint i = start_ind; i < end_ind; i++) {
2904       result = result->next_in_collection_set();
2905     }
2906   }
2907 
2908   // Note: the calculated starting heap region may be NULL
2909   // (when the collection set is empty).
2910   assert(result == NULL || result->in_collection_set(), "sanity");
2911   assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2912          "should be updated only once per pause");
2913   _worker_cset_start_region[worker_i] = result;
2914   OrderAccess::storestore();
2915   _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2916   return result;
2917 }
2918 
2919 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2920                                                      uint no_of_par_workers) {
2921   uint worker_num =
2922            G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2923   assert(UseDynamicNumberOfGCThreads ||
2924          no_of_par_workers == workers()->total_workers(),
2925          "Non dynamic should use fixed number of workers");
2926   const uint start_index = n_regions() * worker_i / worker_num;
2927   return region_at(start_index);
2928 }
2929 
2930 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2931   HeapRegion* r = g1_policy()->collection_set();
2932   while (r != NULL) {
2933     HeapRegion* next = r->next_in_collection_set();
2934     if (cl->doHeapRegion(r)) {
2935       cl->incomplete();
2936       return;
2937     }
2938     r = next;
2939   }
2940 }
2941 
2942 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2943                                                   HeapRegionClosure *cl) {
2944   if (r == NULL) {
2945     // The CSet is empty so there's nothing to do.
2946     return;
2947   }
2948 
2949   assert(r->in_collection_set(),
2950          "Start region must be a member of the collection set.");
2951   HeapRegion* cur = r;
2952   while (cur != NULL) {
2953     HeapRegion* next = cur->next_in_collection_set();
2954     if (cl->doHeapRegion(cur) && false) {
2955       cl->incomplete();
2956       return;
2957     }
2958     cur = next;
2959   }
2960   cur = g1_policy()->collection_set();
2961   while (cur != r) {
2962     HeapRegion* next = cur->next_in_collection_set();
2963     if (cl->doHeapRegion(cur) && false) {
2964       cl->incomplete();
2965       return;
2966     }
2967     cur = next;
2968   }
2969 }
2970 
2971 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2972   return n_regions() > 0 ? region_at(0) : NULL;
2973 }
2974 
2975 
2976 Space* G1CollectedHeap::space_containing(const void* addr) const {
2977   return heap_region_containing(addr);
2978 }
2979 
2980 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2981   Space* sp = space_containing(addr);
2982   return sp->block_start(addr);
2983 }
2984 
2985 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2986   Space* sp = space_containing(addr);
2987   return sp->block_size(addr);
2988 }
2989 
2990 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2991   Space* sp = space_containing(addr);
2992   return sp->block_is_obj(addr);
2993 }
2994 
2995 bool G1CollectedHeap::supports_tlab_allocation() const {
2996   return true;
2997 }
2998 
2999 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3000   return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
3001 }
3002 
3003 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3004   return young_list()->eden_used_bytes();
3005 }
3006 
3007 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3008 // must be smaller than the humongous object limit.
3009 size_t G1CollectedHeap::max_tlab_size() const {
3010   return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3011 }
3012 
3013 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3014   // Return the remaining space in the cur alloc region, but not less than
3015   // the min TLAB size.
3016 
3017   // Also, this value can be at most the humongous object threshold,
3018   // since we can't allow tlabs to grow big enough to accommodate
3019   // humongous objects.
3020 
3021   HeapRegion* hr = _mutator_alloc_region.get();
3022   size_t max_tlab = max_tlab_size() * wordSize;
3023   if (hr == NULL) {
3024     return max_tlab;
3025   } else {
3026     return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3027   }
3028 }
3029 
3030 size_t G1CollectedHeap::max_capacity() const {
3031   return _g1_reserved.byte_size();
3032 }
3033 
3034 jlong G1CollectedHeap::millis_since_last_gc() {
3035   // assert(false, "NYI");
3036   return 0;
3037 }
3038 
3039 void G1CollectedHeap::prepare_for_verify() {
3040   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3041     ensure_parsability(false);
3042   }
3043   g1_rem_set()->prepare_for_verify();
3044 }
3045 
3046 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3047                                               VerifyOption vo) {
3048   switch (vo) {
3049   case VerifyOption_G1UsePrevMarking:
3050     return hr->obj_allocated_since_prev_marking(obj);
3051   case VerifyOption_G1UseNextMarking:
3052     return hr->obj_allocated_since_next_marking(obj);
3053   case VerifyOption_G1UseMarkWord:
3054     return false;
3055   default:
3056     ShouldNotReachHere();
3057   }
3058   return false; // keep some compilers happy
3059 }
3060 
3061 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3062   switch (vo) {
3063   case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3064   case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3065   case VerifyOption_G1UseMarkWord:    return NULL;
3066   default:                            ShouldNotReachHere();
3067   }
3068   return NULL; // keep some compilers happy
3069 }
3070 
3071 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3072   switch (vo) {
3073   case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3074   case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3075   case VerifyOption_G1UseMarkWord:    return obj->is_gc_marked();
3076   default:                            ShouldNotReachHere();
3077   }
3078   return false; // keep some compilers happy
3079 }
3080 
3081 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3082   switch (vo) {
3083   case VerifyOption_G1UsePrevMarking: return "PTAMS";
3084   case VerifyOption_G1UseNextMarking: return "NTAMS";
3085   case VerifyOption_G1UseMarkWord:    return "NONE";
3086   default:                            ShouldNotReachHere();
3087   }
3088   return NULL; // keep some compilers happy
3089 }
3090 
3091 class VerifyRootsClosure: public OopClosure {
3092 private:
3093   G1CollectedHeap* _g1h;
3094   VerifyOption     _vo;
3095   bool             _failures;
3096 public:
3097   // _vo == UsePrevMarking -> use "prev" marking information,
3098   // _vo == UseNextMarking -> use "next" marking information,
3099   // _vo == UseMarkWord    -> use mark word from object header.
3100   VerifyRootsClosure(VerifyOption vo) :
3101     _g1h(G1CollectedHeap::heap()),
3102     _vo(vo),
3103     _failures(false) { }
3104 
3105   bool failures() { return _failures; }
3106 
3107   template <class T> void do_oop_nv(T* p) {
3108     T heap_oop = oopDesc::load_heap_oop(p);
3109     if (!oopDesc::is_null(heap_oop)) {
3110       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3111       if (_g1h->is_obj_dead_cond(obj, _vo)) {
3112         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3113                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
3114         if (_vo == VerifyOption_G1UseMarkWord) {
3115           gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3116         }
3117         obj->print_on(gclog_or_tty);
3118         _failures = true;
3119       }
3120     }
3121   }
3122 
3123   void do_oop(oop* p)       { do_oop_nv(p); }
3124   void do_oop(narrowOop* p) { do_oop_nv(p); }
3125 };
3126 
3127 class G1VerifyCodeRootOopClosure: public OopClosure {
3128   G1CollectedHeap* _g1h;
3129   OopClosure* _root_cl;
3130   nmethod* _nm;
3131   VerifyOption _vo;
3132   bool _failures;
3133 
3134   template <class T> void do_oop_work(T* p) {
3135     // First verify that this root is live
3136     _root_cl->do_oop(p);
3137 
3138     if (!G1VerifyHeapRegionCodeRoots) {
3139       // We're not verifying the code roots attached to heap region.
3140       return;
3141     }
3142 
3143     // Don't check the code roots during marking verification in a full GC
3144     if (_vo == VerifyOption_G1UseMarkWord) {
3145       return;
3146     }
3147 
3148     // Now verify that the current nmethod (which contains p) is
3149     // in the code root list of the heap region containing the
3150     // object referenced by p.
3151 
3152     T heap_oop = oopDesc::load_heap_oop(p);
3153     if (!oopDesc::is_null(heap_oop)) {
3154       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3155 
3156       // Now fetch the region containing the object
3157       HeapRegion* hr = _g1h->heap_region_containing(obj);
3158       HeapRegionRemSet* hrrs = hr->rem_set();
3159       // Verify that the strong code root list for this region
3160       // contains the nmethod
3161       if (!hrrs->strong_code_roots_list_contains(_nm)) {
3162         gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3163                               "from nmethod "PTR_FORMAT" not in strong "
3164                               "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3165                               p, _nm, hr->bottom(), hr->end());
3166         _failures = true;
3167       }
3168     }
3169   }
3170 
3171 public:
3172   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3173     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3174 
3175   void do_oop(oop* p) { do_oop_work(p); }
3176   void do_oop(narrowOop* p) { do_oop_work(p); }
3177 
3178   void set_nmethod(nmethod* nm) { _nm = nm; }
3179   bool failures() { return _failures; }
3180 };
3181 
3182 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3183   G1VerifyCodeRootOopClosure* _oop_cl;
3184 
3185 public:
3186   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3187     _oop_cl(oop_cl) {}
3188 
3189   void do_code_blob(CodeBlob* cb) {
3190     nmethod* nm = cb->as_nmethod_or_null();
3191     if (nm != NULL) {
3192       _oop_cl->set_nmethod(nm);
3193       nm->oops_do(_oop_cl);
3194     }
3195   }
3196 };
3197 
3198 class YoungRefCounterClosure : public OopClosure {
3199   G1CollectedHeap* _g1h;
3200   int              _count;
3201  public:
3202   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3203   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
3204   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3205 
3206   int count() { return _count; }
3207   void reset_count() { _count = 0; };
3208 };
3209 
3210 class VerifyKlassClosure: public KlassClosure {
3211   YoungRefCounterClosure _young_ref_counter_closure;
3212   OopClosure *_oop_closure;
3213  public:
3214   VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3215   void do_klass(Klass* k) {
3216     k->oops_do(_oop_closure);
3217 
3218     _young_ref_counter_closure.reset_count();
3219     k->oops_do(&_young_ref_counter_closure);
3220     if (_young_ref_counter_closure.count() > 0) {
3221       guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3222     }
3223   }
3224 };
3225 
3226 class VerifyLivenessOopClosure: public OopClosure {
3227   G1CollectedHeap* _g1h;
3228   VerifyOption _vo;
3229 public:
3230   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3231     _g1h(g1h), _vo(vo)
3232   { }
3233   void do_oop(narrowOop *p) { do_oop_work(p); }
3234   void do_oop(      oop *p) { do_oop_work(p); }
3235 
3236   template <class T> void do_oop_work(T *p) {
3237     oop obj = oopDesc::load_decode_heap_oop(p);
3238     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3239               "Dead object referenced by a not dead object");
3240   }
3241 };
3242 
3243 class VerifyObjsInRegionClosure: public ObjectClosure {
3244 private:
3245   G1CollectedHeap* _g1h;
3246   size_t _live_bytes;
3247   HeapRegion *_hr;
3248   VerifyOption _vo;
3249 public:
3250   // _vo == UsePrevMarking -> use "prev" marking information,
3251   // _vo == UseNextMarking -> use "next" marking information,
3252   // _vo == UseMarkWord    -> use mark word from object header.
3253   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3254     : _live_bytes(0), _hr(hr), _vo(vo) {
3255     _g1h = G1CollectedHeap::heap();
3256   }
3257   void do_object(oop o) {
3258     VerifyLivenessOopClosure isLive(_g1h, _vo);
3259     assert(o != NULL, "Huh?");
3260     if (!_g1h->is_obj_dead_cond(o, _vo)) {
3261       // If the object is alive according to the mark word,
3262       // then verify that the marking information agrees.
3263       // Note we can't verify the contra-positive of the
3264       // above: if the object is dead (according to the mark
3265       // word), it may not be marked, or may have been marked
3266       // but has since became dead, or may have been allocated
3267       // since the last marking.
3268       if (_vo == VerifyOption_G1UseMarkWord) {
3269         guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3270       }
3271 
3272       o->oop_iterate_no_header(&isLive);
3273       if (!_hr->obj_allocated_since_prev_marking(o)) {
3274         size_t obj_size = o->size();    // Make sure we don't overflow
3275         _live_bytes += (obj_size * HeapWordSize);
3276       }
3277     }
3278   }
3279   size_t live_bytes() { return _live_bytes; }
3280 };
3281 
3282 class PrintObjsInRegionClosure : public ObjectClosure {
3283   HeapRegion *_hr;
3284   G1CollectedHeap *_g1;
3285 public:
3286   PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3287     _g1 = G1CollectedHeap::heap();
3288   };
3289 
3290   void do_object(oop o) {
3291     if (o != NULL) {
3292       HeapWord *start = (HeapWord *) o;
3293       size_t word_sz = o->size();
3294       gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3295                           " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3296                           (void*) o, word_sz,
3297                           _g1->isMarkedPrev(o),
3298                           _g1->isMarkedNext(o),
3299                           _hr->obj_allocated_since_prev_marking(o));
3300       HeapWord *end = start + word_sz;
3301       HeapWord *cur;
3302       int *val;
3303       for (cur = start; cur < end; cur++) {
3304         val = (int *) cur;
3305         gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3306       }
3307     }
3308   }
3309 };
3310 
3311 class VerifyRegionClosure: public HeapRegionClosure {
3312 private:
3313   bool             _par;
3314   VerifyOption     _vo;
3315   bool             _failures;
3316 public:
3317   // _vo == UsePrevMarking -> use "prev" marking information,
3318   // _vo == UseNextMarking -> use "next" marking information,
3319   // _vo == UseMarkWord    -> use mark word from object header.
3320   VerifyRegionClosure(bool par, VerifyOption vo)
3321     : _par(par),
3322       _vo(vo),
3323       _failures(false) {}
3324 
3325   bool failures() {
3326     return _failures;
3327   }
3328 
3329   bool doHeapRegion(HeapRegion* r) {
3330     if (!r->continuesHumongous()) {
3331       bool failures = false;
3332       r->verify(_vo, &failures);
3333       if (failures) {
3334         _failures = true;
3335       } else {
3336         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3337         r->object_iterate(&not_dead_yet_cl);
3338         if (_vo != VerifyOption_G1UseNextMarking) {
3339           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3340             gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3341                                    "max_live_bytes "SIZE_FORMAT" "
3342                                    "< calculated "SIZE_FORMAT,
3343                                    r->bottom(), r->end(),
3344                                    r->max_live_bytes(),
3345                                  not_dead_yet_cl.live_bytes());
3346             _failures = true;
3347           }
3348         } else {
3349           // When vo == UseNextMarking we cannot currently do a sanity
3350           // check on the live bytes as the calculation has not been
3351           // finalized yet.
3352         }
3353       }
3354     }
3355     return false; // stop the region iteration if we hit a failure
3356   }
3357 };
3358 
3359 // This is the task used for parallel verification of the heap regions
3360 
3361 class G1ParVerifyTask: public AbstractGangTask {
3362 private:
3363   G1CollectedHeap* _g1h;
3364   VerifyOption     _vo;
3365   bool             _failures;
3366 
3367 public:
3368   // _vo == UsePrevMarking -> use "prev" marking information,
3369   // _vo == UseNextMarking -> use "next" marking information,
3370   // _vo == UseMarkWord    -> use mark word from object header.
3371   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3372     AbstractGangTask("Parallel verify task"),
3373     _g1h(g1h),
3374     _vo(vo),
3375     _failures(false) { }
3376 
3377   bool failures() {
3378     return _failures;
3379   }
3380 
3381   void work(uint worker_id) {
3382     HandleMark hm;
3383     VerifyRegionClosure blk(true, _vo);
3384     _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3385                                           _g1h->workers()->active_workers(),
3386                                           HeapRegion::ParVerifyClaimValue);
3387     if (blk.failures()) {
3388       _failures = true;
3389     }
3390   }
3391 };
3392 
3393 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3394   if (SafepointSynchronize::is_at_safepoint()) {
3395     assert(Thread::current()->is_VM_thread(),
3396            "Expected to be executed serially by the VM thread at this point");
3397 
3398     if (!silent) { gclog_or_tty->print("Roots "); }
3399     VerifyRootsClosure rootsCl(vo);
3400     VerifyKlassClosure klassCl(this, &rootsCl);
3401 
3402     // We apply the relevant closures to all the oops in the
3403     // system dictionary, class loader data graph and the string table.
3404     // Don't verify the code cache here, since it's verified below.
3405     const int so = SO_AllClasses | SO_Strings;
3406 
3407     // Need cleared claim bits for the strong roots processing
3408     ClassLoaderDataGraph::clear_claimed_marks();
3409 
3410     process_strong_roots(true,      // activate StrongRootsScope
3411                          ScanningOption(so),  // roots scanning options
3412                          &rootsCl,
3413                          &klassCl
3414                          );
3415 
3416     // Verify the nmethods in the code cache.
3417     G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3418     G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3419     CodeCache::blobs_do(&blobsCl);
3420 
3421     bool failures = rootsCl.failures() || codeRootsCl.failures();
3422 
3423     if (vo != VerifyOption_G1UseMarkWord) {
3424       // If we're verifying during a full GC then the region sets
3425       // will have been torn down at the start of the GC. Therefore
3426       // verifying the region sets will fail. So we only verify
3427       // the region sets when not in a full GC.
3428       if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3429       verify_region_sets();
3430     }
3431 
3432     if (!silent) { gclog_or_tty->print("HeapRegions "); }
3433     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3434       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3435              "sanity check");
3436 
3437       G1ParVerifyTask task(this, vo);
3438       assert(UseDynamicNumberOfGCThreads ||
3439         workers()->active_workers() == workers()->total_workers(),
3440         "If not dynamic should be using all the workers");
3441       int n_workers = workers()->active_workers();
3442       set_par_threads(n_workers);
3443       workers()->run_task(&task);
3444       set_par_threads(0);
3445       if (task.failures()) {
3446         failures = true;
3447       }
3448 
3449       // Checks that the expected amount of parallel work was done.
3450       // The implication is that n_workers is > 0.
3451       assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3452              "sanity check");
3453 
3454       reset_heap_region_claim_values();
3455 
3456       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3457              "sanity check");
3458     } else {
3459       VerifyRegionClosure blk(false, vo);
3460       heap_region_iterate(&blk);
3461       if (blk.failures()) {
3462         failures = true;
3463       }
3464     }
3465     if (!silent) gclog_or_tty->print("RemSet ");
3466     rem_set()->verify();
3467 
3468     if (G1StringDedup::is_enabled()) {
3469       if (!silent) gclog_or_tty->print("StrDedup ");
3470       G1StringDedup::verify();
3471     }
3472 
3473     if (failures) {
3474       gclog_or_tty->print_cr("Heap:");
3475       // It helps to have the per-region information in the output to
3476       // help us track down what went wrong. This is why we call
3477       // print_extended_on() instead of print_on().
3478       print_extended_on(gclog_or_tty);
3479       gclog_or_tty->cr();
3480 #ifndef PRODUCT
3481       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3482         concurrent_mark()->print_reachable("at-verification-failure",
3483                                            vo, false /* all */);
3484       }
3485 #endif
3486       gclog_or_tty->flush();
3487     }
3488     guarantee(!failures, "there should not have been any failures");
3489   } else {
3490     if (!silent) {
3491       gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3492       if (G1StringDedup::is_enabled()) {
3493         gclog_or_tty->print(", StrDedup");
3494       }
3495       gclog_or_tty->print(") ");
3496     }
3497   }
3498 }
3499 
3500 void G1CollectedHeap::verify(bool silent) {
3501   verify(silent, VerifyOption_G1UsePrevMarking);
3502 }
3503 
3504 double G1CollectedHeap::verify(bool guard, const char* msg) {
3505   double verify_time_ms = 0.0;
3506 
3507   if (guard && total_collections() >= VerifyGCStartAt) {
3508     double verify_start = os::elapsedTime();
3509     HandleMark hm;  // Discard invalid handles created during verification
3510     prepare_for_verify();
3511     Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3512     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3513   }
3514 
3515   return verify_time_ms;
3516 }
3517 
3518 void G1CollectedHeap::verify_before_gc() {
3519   double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3520   g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3521 }
3522 
3523 void G1CollectedHeap::verify_after_gc() {
3524   double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3525   g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3526 }
3527 
3528 class PrintRegionClosure: public HeapRegionClosure {
3529   outputStream* _st;
3530 public:
3531   PrintRegionClosure(outputStream* st) : _st(st) {}
3532   bool doHeapRegion(HeapRegion* r) {
3533     r->print_on(_st);
3534     return false;
3535   }
3536 };
3537 
3538 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3539                                        const HeapRegion* hr,
3540                                        const VerifyOption vo) const {
3541   switch (vo) {
3542   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3543   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3544   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3545   default:                            ShouldNotReachHere();
3546   }
3547   return false; // keep some compilers happy
3548 }
3549 
3550 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3551                                        const VerifyOption vo) const {
3552   switch (vo) {
3553   case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3554   case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3555   case VerifyOption_G1UseMarkWord:    return !obj->is_gc_marked();
3556   default:                            ShouldNotReachHere();
3557   }
3558   return false; // keep some compilers happy
3559 }
3560 
3561 void G1CollectedHeap::print_on(outputStream* st) const {
3562   st->print(" %-20s", "garbage-first heap");
3563   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3564             capacity()/K, used_unlocked()/K);
3565   st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3566             _g1_storage.low_boundary(),
3567             _g1_storage.high(),
3568             _g1_storage.high_boundary());
3569   st->cr();
3570   st->print("  region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3571   uint young_regions = _young_list->length();
3572   st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3573             (size_t) young_regions * HeapRegion::GrainBytes / K);
3574   uint survivor_regions = g1_policy()->recorded_survivor_regions();
3575   st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3576             (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3577   st->cr();
3578   MetaspaceAux::print_on(st);
3579 }
3580 
3581 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3582   print_on(st);
3583 
3584   // Print the per-region information.
3585   st->cr();
3586   st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3587                "HS=humongous(starts), HC=humongous(continues), "
3588                "CS=collection set, F=free, TS=gc time stamp, "
3589                "PTAMS=previous top-at-mark-start, "
3590                "NTAMS=next top-at-mark-start)");
3591   PrintRegionClosure blk(st);
3592   heap_region_iterate(&blk);
3593 }
3594 
3595 void G1CollectedHeap::print_on_error(outputStream* st) const {
3596   this->CollectedHeap::print_on_error(st);
3597 
3598   if (_cm != NULL) {
3599     st->cr();
3600     _cm->print_on_error(st);
3601   }
3602 }
3603 
3604 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3605   if (G1CollectedHeap::use_parallel_gc_threads()) {
3606     workers()->print_worker_threads_on(st);
3607   }
3608   _cmThread->print_on(st);
3609   st->cr();
3610   _cm->print_worker_threads_on(st);
3611   _cg1r->print_worker_threads_on(st);
3612   if (G1StringDedup::is_enabled()) {
3613     G1StringDedup::print_worker_threads_on(st);
3614   }
3615 }
3616 
3617 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3618   if (G1CollectedHeap::use_parallel_gc_threads()) {
3619     workers()->threads_do(tc);
3620   }
3621   tc->do_thread(_cmThread);
3622   _cg1r->threads_do(tc);
3623   if (G1StringDedup::is_enabled()) {
3624     G1StringDedup::threads_do(tc);
3625   }
3626 }
3627 
3628 void G1CollectedHeap::print_tracing_info() const {
3629   // We'll overload this to mean "trace GC pause statistics."
3630   if (TraceGen0Time || TraceGen1Time) {
3631     // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3632     // to that.
3633     g1_policy()->print_tracing_info();
3634   }
3635   if (G1SummarizeRSetStats) {
3636     g1_rem_set()->print_summary_info();
3637   }
3638   if (G1SummarizeConcMark) {
3639     concurrent_mark()->print_summary_info();
3640   }
3641   g1_policy()->print_yg_surv_rate_info();
3642   SpecializationStats::print();
3643 }
3644 
3645 #ifndef PRODUCT
3646 // Helpful for debugging RSet issues.
3647 
3648 class PrintRSetsClosure : public HeapRegionClosure {
3649 private:
3650   const char* _msg;
3651   size_t _occupied_sum;
3652 
3653 public:
3654   bool doHeapRegion(HeapRegion* r) {
3655     HeapRegionRemSet* hrrs = r->rem_set();
3656     size_t occupied = hrrs->occupied();
3657     _occupied_sum += occupied;
3658 
3659     gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3660                            HR_FORMAT_PARAMS(r));
3661     if (occupied == 0) {
3662       gclog_or_tty->print_cr("  RSet is empty");
3663     } else {
3664       hrrs->print();
3665     }
3666     gclog_or_tty->print_cr("----------");
3667     return false;
3668   }
3669 
3670   PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3671     gclog_or_tty->cr();
3672     gclog_or_tty->print_cr("========================================");
3673     gclog_or_tty->print_cr("%s", msg);
3674     gclog_or_tty->cr();
3675   }
3676 
3677   ~PrintRSetsClosure() {
3678     gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3679     gclog_or_tty->print_cr("========================================");
3680     gclog_or_tty->cr();
3681   }
3682 };
3683 
3684 void G1CollectedHeap::print_cset_rsets() {
3685   PrintRSetsClosure cl("Printing CSet RSets");
3686   collection_set_iterate(&cl);
3687 }
3688 
3689 void G1CollectedHeap::print_all_rsets() {
3690   PrintRSetsClosure cl("Printing All RSets");;
3691   heap_region_iterate(&cl);
3692 }
3693 #endif // PRODUCT
3694 
3695 G1CollectedHeap* G1CollectedHeap::heap() {
3696   assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3697          "not a garbage-first heap");
3698   return _g1h;
3699 }
3700 
3701 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3702   // always_do_update_barrier = false;
3703   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3704   // Fill TLAB's and such
3705   accumulate_statistics_all_tlabs();
3706   ensure_parsability(true);
3707 
3708   if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3709       (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3710     g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3711   }
3712 }
3713 
3714 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3715 
3716   if (G1SummarizeRSetStats &&
3717       (G1SummarizeRSetStatsPeriod > 0) &&
3718       // we are at the end of the GC. Total collections has already been increased.
3719       ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3720     g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3721   }
3722 
3723   // FIXME: what is this about?
3724   // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3725   // is set.
3726   COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3727                         "derived pointer present"));
3728   // always_do_update_barrier = true;
3729 
3730   resize_all_tlabs();
3731 
3732   // We have just completed a GC. Update the soft reference
3733   // policy with the new heap occupancy
3734   Universe::update_heap_info_at_gc();
3735 }
3736 
3737 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3738                                                unsigned int gc_count_before,
3739                                                bool* succeeded,
3740                                                GCCause::Cause gc_cause) {
3741   assert_heap_not_locked_and_not_at_safepoint();
3742   g1_policy()->record_stop_world_start();
3743   VM_G1IncCollectionPause op(gc_count_before,
3744                              word_size,
3745                              false, /* should_initiate_conc_mark */
3746                              g1_policy()->max_pause_time_ms(),
3747                              gc_cause);
3748   VMThread::execute(&op);
3749 
3750   HeapWord* result = op.result();
3751   bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3752   assert(result == NULL || ret_succeeded,
3753          "the result should be NULL if the VM did not succeed");
3754   *succeeded = ret_succeeded;
3755 
3756   assert_heap_not_locked();
3757   return result;
3758 }
3759 
3760 void
3761 G1CollectedHeap::doConcurrentMark() {
3762   MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3763   if (!_cmThread->in_progress()) {
3764     _cmThread->set_started();
3765     CGC_lock->notify();
3766   }
3767 }
3768 
3769 size_t G1CollectedHeap::pending_card_num() {
3770   size_t extra_cards = 0;
3771   JavaThread *curr = Threads::first();
3772   while (curr != NULL) {
3773     DirtyCardQueue& dcq = curr->dirty_card_queue();
3774     extra_cards += dcq.size();
3775     curr = curr->next();
3776   }
3777   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3778   size_t buffer_size = dcqs.buffer_size();
3779   size_t buffer_num = dcqs.completed_buffers_num();
3780 
3781   // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3782   // in bytes - not the number of 'entries'. We need to convert
3783   // into a number of cards.
3784   return (buffer_size * buffer_num + extra_cards) / oopSize;
3785 }
3786 
3787 size_t G1CollectedHeap::cards_scanned() {
3788   return g1_rem_set()->cardsScanned();
3789 }
3790 
3791 void
3792 G1CollectedHeap::setup_surviving_young_words() {
3793   assert(_surviving_young_words == NULL, "pre-condition");
3794   uint array_length = g1_policy()->young_cset_region_length();
3795   _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3796   if (_surviving_young_words == NULL) {
3797     vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3798                           "Not enough space for young surv words summary.");
3799   }
3800   memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3801 #ifdef ASSERT
3802   for (uint i = 0;  i < array_length; ++i) {
3803     assert( _surviving_young_words[i] == 0, "memset above" );
3804   }
3805 #endif // !ASSERT
3806 }
3807 
3808 void
3809 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3810   MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3811   uint array_length = g1_policy()->young_cset_region_length();
3812   for (uint i = 0; i < array_length; ++i) {
3813     _surviving_young_words[i] += surv_young_words[i];
3814   }
3815 }
3816 
3817 void
3818 G1CollectedHeap::cleanup_surviving_young_words() {
3819   guarantee( _surviving_young_words != NULL, "pre-condition" );
3820   FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3821   _surviving_young_words = NULL;
3822 }
3823 
3824 #ifdef ASSERT
3825 class VerifyCSetClosure: public HeapRegionClosure {
3826 public:
3827   bool doHeapRegion(HeapRegion* hr) {
3828     // Here we check that the CSet region's RSet is ready for parallel
3829     // iteration. The fields that we'll verify are only manipulated
3830     // when the region is part of a CSet and is collected. Afterwards,
3831     // we reset these fields when we clear the region's RSet (when the
3832     // region is freed) so they are ready when the region is
3833     // re-allocated. The only exception to this is if there's an
3834     // evacuation failure and instead of freeing the region we leave
3835     // it in the heap. In that case, we reset these fields during
3836     // evacuation failure handling.
3837     guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3838 
3839     // Here's a good place to add any other checks we'd like to
3840     // perform on CSet regions.
3841     return false;
3842   }
3843 };
3844 #endif // ASSERT
3845 
3846 #if TASKQUEUE_STATS
3847 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3848   st->print_raw_cr("GC Task Stats");
3849   st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3850   st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3851 }
3852 
3853 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3854   print_taskqueue_stats_hdr(st);
3855 
3856   TaskQueueStats totals;
3857   const int n = workers() != NULL ? workers()->total_workers() : 1;
3858   for (int i = 0; i < n; ++i) {
3859     st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3860     totals += task_queue(i)->stats;
3861   }
3862   st->print_raw("tot "); totals.print(st); st->cr();
3863 
3864   DEBUG_ONLY(totals.verify());
3865 }
3866 
3867 void G1CollectedHeap::reset_taskqueue_stats() {
3868   const int n = workers() != NULL ? workers()->total_workers() : 1;
3869   for (int i = 0; i < n; ++i) {
3870     task_queue(i)->stats.reset();
3871   }
3872 }
3873 #endif // TASKQUEUE_STATS
3874 
3875 void G1CollectedHeap::log_gc_header() {
3876   if (!G1Log::fine()) {
3877     return;
3878   }
3879 
3880   gclog_or_tty->date_stamp(PrintGCDateStamps);
3881   gclog_or_tty->stamp(PrintGCTimeStamps);
3882 
3883   GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3884     .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3885     .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3886 
3887   gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3888 }
3889 
3890 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3891   if (!G1Log::fine()) {
3892     return;
3893   }
3894 
3895   if (G1Log::finer()) {
3896     if (evacuation_failed()) {
3897       gclog_or_tty->print(" (to-space exhausted)");
3898     }
3899     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3900     g1_policy()->phase_times()->note_gc_end();
3901     g1_policy()->phase_times()->print(pause_time_sec);
3902     g1_policy()->print_detailed_heap_transition();
3903   } else {
3904     if (evacuation_failed()) {
3905       gclog_or_tty->print("--");
3906     }
3907     g1_policy()->print_heap_transition();
3908     gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3909   }
3910   gclog_or_tty->flush();
3911 }
3912 
3913 bool
3914 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3915   assert_at_safepoint(true /* should_be_vm_thread */);
3916   guarantee(!is_gc_active(), "collection is not reentrant");
3917 
3918   if (GC_locker::check_active_before_gc()) {
3919     return false;
3920   }
3921 
3922   _gc_timer_stw->register_gc_start();
3923 
3924   _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3925 
3926   SvcGCMarker sgcm(SvcGCMarker::MINOR);
3927   ResourceMark rm;
3928 
3929   print_heap_before_gc();
3930   trace_heap_before_gc(_gc_tracer_stw);
3931 
3932   verify_region_sets_optional();
3933   verify_dirty_young_regions();
3934 
3935   // This call will decide whether this pause is an initial-mark
3936   // pause. If it is, during_initial_mark_pause() will return true
3937   // for the duration of this pause.
3938   g1_policy()->decide_on_conc_mark_initiation();
3939 
3940   // We do not allow initial-mark to be piggy-backed on a mixed GC.
3941   assert(!g1_policy()->during_initial_mark_pause() ||
3942           g1_policy()->gcs_are_young(), "sanity");
3943 
3944   // We also do not allow mixed GCs during marking.
3945   assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3946 
3947   // Record whether this pause is an initial mark. When the current
3948   // thread has completed its logging output and it's safe to signal
3949   // the CM thread, the flag's value in the policy has been reset.
3950   bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3951 
3952   // Inner scope for scope based logging, timers, and stats collection
3953   {
3954     EvacuationInfo evacuation_info;
3955 
3956     if (g1_policy()->during_initial_mark_pause()) {
3957       // We are about to start a marking cycle, so we increment the
3958       // full collection counter.
3959       increment_old_marking_cycles_started();
3960       register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3961     }
3962 
3963     _gc_tracer_stw->report_yc_type(yc_type());
3964 
3965     TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3966 
3967     int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3968                                 workers()->active_workers() : 1);
3969     double pause_start_sec = os::elapsedTime();
3970     g1_policy()->phase_times()->note_gc_start(active_workers);
3971     log_gc_header();
3972 
3973     TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3974     TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3975 
3976     // If the secondary_free_list is not empty, append it to the
3977     // free_list. No need to wait for the cleanup operation to finish;
3978     // the region allocation code will check the secondary_free_list
3979     // and wait if necessary. If the G1StressConcRegionFreeing flag is
3980     // set, skip this step so that the region allocation code has to
3981     // get entries from the secondary_free_list.
3982     if (!G1StressConcRegionFreeing) {
3983       append_secondary_free_list_if_not_empty_with_lock();
3984     }
3985 
3986     assert(check_young_list_well_formed(), "young list should be well formed");
3987     assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3988            "sanity check");
3989 
3990     // Don't dynamically change the number of GC threads this early.  A value of
3991     // 0 is used to indicate serial work.  When parallel work is done,
3992     // it will be set.
3993 
3994     { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3995       IsGCActiveMark x;
3996 
3997       gc_prologue(false);
3998       increment_total_collections(false /* full gc */);
3999       increment_gc_time_stamp();
4000 
4001       verify_before_gc();
4002       check_bitmaps("GC Start");
4003 
4004       COMPILER2_PRESENT(DerivedPointerTable::clear());
4005 
4006       // Please see comment in g1CollectedHeap.hpp and
4007       // G1CollectedHeap::ref_processing_init() to see how
4008       // reference processing currently works in G1.
4009 
4010       // Enable discovery in the STW reference processor
4011       ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4012                                             true /*verify_no_refs*/);
4013 
4014       {
4015         // We want to temporarily turn off discovery by the
4016         // CM ref processor, if necessary, and turn it back on
4017         // on again later if we do. Using a scoped
4018         // NoRefDiscovery object will do this.
4019         NoRefDiscovery no_cm_discovery(ref_processor_cm());
4020 
4021         // Forget the current alloc region (we might even choose it to be part
4022         // of the collection set!).
4023         release_mutator_alloc_region();
4024 
4025         // We should call this after we retire the mutator alloc
4026         // region(s) so that all the ALLOC / RETIRE events are generated
4027         // before the start GC event.
4028         _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4029 
4030         // This timing is only used by the ergonomics to handle our pause target.
4031         // It is unclear why this should not include the full pause. We will
4032         // investigate this in CR 7178365.
4033         //
4034         // Preserving the old comment here if that helps the investigation:
4035         //
4036         // The elapsed time induced by the start time below deliberately elides
4037         // the possible verification above.
4038         double sample_start_time_sec = os::elapsedTime();
4039 
4040 #if YOUNG_LIST_VERBOSE
4041         gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4042         _young_list->print();
4043         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4044 #endif // YOUNG_LIST_VERBOSE
4045 
4046         g1_policy()->record_collection_pause_start(sample_start_time_sec);
4047 
4048         double scan_wait_start = os::elapsedTime();
4049         // We have to wait until the CM threads finish scanning the
4050         // root regions as it's the only way to ensure that all the
4051         // objects on them have been correctly scanned before we start
4052         // moving them during the GC.
4053         bool waited = _cm->root_regions()->wait_until_scan_finished();
4054         double wait_time_ms = 0.0;
4055         if (waited) {
4056           double scan_wait_end = os::elapsedTime();
4057           wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4058         }
4059         g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4060 
4061 #if YOUNG_LIST_VERBOSE
4062         gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4063         _young_list->print();
4064 #endif // YOUNG_LIST_VERBOSE
4065 
4066         if (g1_policy()->during_initial_mark_pause()) {
4067           concurrent_mark()->checkpointRootsInitialPre();
4068         }
4069 
4070 #if YOUNG_LIST_VERBOSE
4071         gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4072         _young_list->print();
4073         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4074 #endif // YOUNG_LIST_VERBOSE
4075 
4076         g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4077 
4078         _cm->note_start_of_gc();
4079         // We should not verify the per-thread SATB buffers given that
4080         // we have not filtered them yet (we'll do so during the
4081         // GC). We also call this after finalize_cset() to
4082         // ensure that the CSet has been finalized.
4083         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4084                                  true  /* verify_enqueued_buffers */,
4085                                  false /* verify_thread_buffers */,
4086                                  true  /* verify_fingers */);
4087 
4088         if (_hr_printer.is_active()) {
4089           HeapRegion* hr = g1_policy()->collection_set();
4090           while (hr != NULL) {
4091             G1HRPrinter::RegionType type;
4092             if (!hr->is_young()) {
4093               type = G1HRPrinter::Old;
4094             } else if (hr->is_survivor()) {
4095               type = G1HRPrinter::Survivor;
4096             } else {
4097               type = G1HRPrinter::Eden;
4098             }
4099             _hr_printer.cset(hr);
4100             hr = hr->next_in_collection_set();
4101           }
4102         }
4103 
4104 #ifdef ASSERT
4105         VerifyCSetClosure cl;
4106         collection_set_iterate(&cl);
4107 #endif // ASSERT
4108 
4109         setup_surviving_young_words();
4110 
4111         // Initialize the GC alloc regions.
4112         init_gc_alloc_regions(evacuation_info);
4113 
4114         // Actually do the work...
4115         evacuate_collection_set(evacuation_info);
4116 
4117         // We do this to mainly verify the per-thread SATB buffers
4118         // (which have been filtered by now) since we didn't verify
4119         // them earlier. No point in re-checking the stacks / enqueued
4120         // buffers given that the CSet has not changed since last time
4121         // we checked.
4122         _cm->verify_no_cset_oops(false /* verify_stacks */,
4123                                  false /* verify_enqueued_buffers */,
4124                                  true  /* verify_thread_buffers */,
4125                                  true  /* verify_fingers */);
4126 
4127         free_collection_set(g1_policy()->collection_set(), evacuation_info);
4128         g1_policy()->clear_collection_set();
4129 
4130         cleanup_surviving_young_words();
4131 
4132         // Start a new incremental collection set for the next pause.
4133         g1_policy()->start_incremental_cset_building();
4134 
4135         clear_cset_fast_test();
4136 
4137         _young_list->reset_sampled_info();
4138 
4139         // Don't check the whole heap at this point as the
4140         // GC alloc regions from this pause have been tagged
4141         // as survivors and moved on to the survivor list.
4142         // Survivor regions will fail the !is_young() check.
4143         assert(check_young_list_empty(false /* check_heap */),
4144           "young list should be empty");
4145 
4146 #if YOUNG_LIST_VERBOSE
4147         gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4148         _young_list->print();
4149 #endif // YOUNG_LIST_VERBOSE
4150 
4151         g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4152                                              _young_list->first_survivor_region(),
4153                                              _young_list->last_survivor_region());
4154 
4155         _young_list->reset_auxilary_lists();
4156 
4157         if (evacuation_failed()) {
4158           _summary_bytes_used = recalculate_used();
4159           uint n_queues = MAX2((int)ParallelGCThreads, 1);
4160           for (uint i = 0; i < n_queues; i++) {
4161             if (_evacuation_failed_info_array[i].has_failed()) {
4162               _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4163             }
4164           }
4165         } else {
4166           // The "used" of the the collection set have already been subtracted
4167           // when they were freed.  Add in the bytes evacuated.
4168           _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4169         }
4170 
4171         if (g1_policy()->during_initial_mark_pause()) {
4172           // We have to do this before we notify the CM threads that
4173           // they can start working to make sure that all the
4174           // appropriate initialization is done on the CM object.
4175           concurrent_mark()->checkpointRootsInitialPost();
4176           set_marking_started();
4177           // Note that we don't actually trigger the CM thread at
4178           // this point. We do that later when we're sure that
4179           // the current thread has completed its logging output.
4180         }
4181 
4182         allocate_dummy_regions();
4183 
4184 #if YOUNG_LIST_VERBOSE
4185         gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4186         _young_list->print();
4187         g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4188 #endif // YOUNG_LIST_VERBOSE
4189 
4190         init_mutator_alloc_region();
4191 
4192         {
4193           size_t expand_bytes = g1_policy()->expansion_amount();
4194           if (expand_bytes > 0) {
4195             size_t bytes_before = capacity();
4196             // No need for an ergo verbose message here,
4197             // expansion_amount() does this when it returns a value > 0.
4198             if (!expand(expand_bytes)) {
4199               // We failed to expand the heap so let's verify that
4200               // committed/uncommitted amount match the backing store
4201               assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4202               assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4203             }
4204           }
4205         }
4206 
4207         // We redo the verification but now wrt to the new CSet which
4208         // has just got initialized after the previous CSet was freed.
4209         _cm->verify_no_cset_oops(true  /* verify_stacks */,
4210                                  true  /* verify_enqueued_buffers */,
4211                                  true  /* verify_thread_buffers */,
4212                                  true  /* verify_fingers */);
4213         _cm->note_end_of_gc();
4214 
4215         // This timing is only used by the ergonomics to handle our pause target.
4216         // It is unclear why this should not include the full pause. We will
4217         // investigate this in CR 7178365.
4218         double sample_end_time_sec = os::elapsedTime();
4219         double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4220         g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4221 
4222         MemoryService::track_memory_usage();
4223 
4224         // In prepare_for_verify() below we'll need to scan the deferred
4225         // update buffers to bring the RSets up-to-date if
4226         // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4227         // the update buffers we'll probably need to scan cards on the
4228         // regions we just allocated to (i.e., the GC alloc
4229         // regions). However, during the last GC we called
4230         // set_saved_mark() on all the GC alloc regions, so card
4231         // scanning might skip the [saved_mark_word()...top()] area of
4232         // those regions (i.e., the area we allocated objects into
4233         // during the last GC). But it shouldn't. Given that
4234         // saved_mark_word() is conditional on whether the GC time stamp
4235         // on the region is current or not, by incrementing the GC time
4236         // stamp here we invalidate all the GC time stamps on all the
4237         // regions and saved_mark_word() will simply return top() for
4238         // all the regions. This is a nicer way of ensuring this rather
4239         // than iterating over the regions and fixing them. In fact, the
4240         // GC time stamp increment here also ensures that
4241         // saved_mark_word() will return top() between pauses, i.e.,
4242         // during concurrent refinement. So we don't need the
4243         // is_gc_active() check to decided which top to use when
4244         // scanning cards (see CR 7039627).
4245         increment_gc_time_stamp();
4246 
4247         verify_after_gc();
4248         check_bitmaps("GC End");
4249 
4250         assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4251         ref_processor_stw()->verify_no_references_recorded();
4252 
4253         // CM reference discovery will be re-enabled if necessary.
4254       }
4255 
4256       // We should do this after we potentially expand the heap so
4257       // that all the COMMIT events are generated before the end GC
4258       // event, and after we retire the GC alloc regions so that all
4259       // RETIRE events are generated before the end GC event.
4260       _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4261 
4262       if (mark_in_progress()) {
4263         concurrent_mark()->update_g1_committed();
4264       }
4265 
4266 #ifdef TRACESPINNING
4267       ParallelTaskTerminator::print_termination_counts();
4268 #endif
4269 
4270       gc_epilogue(false);
4271     }
4272 
4273     // Print the remainder of the GC log output.
4274     log_gc_footer(os::elapsedTime() - pause_start_sec);
4275 
4276     // It is not yet to safe to tell the concurrent mark to
4277     // start as we have some optional output below. We don't want the
4278     // output from the concurrent mark thread interfering with this
4279     // logging output either.
4280 
4281     _hrs.verify_optional();
4282     verify_region_sets_optional();
4283 
4284     TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4285     TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4286 
4287     print_heap_after_gc();
4288     trace_heap_after_gc(_gc_tracer_stw);
4289 
4290     // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4291     // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4292     // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4293     // before any GC notifications are raised.
4294     g1mm()->update_sizes();
4295 
4296     _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4297     _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4298     _gc_timer_stw->register_gc_end();
4299     _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4300   }
4301   // It should now be safe to tell the concurrent mark thread to start
4302   // without its logging output interfering with the logging output
4303   // that came from the pause.
4304 
4305   if (should_start_conc_mark) {
4306     // CAUTION: after the doConcurrentMark() call below,
4307     // the concurrent marking thread(s) could be running
4308     // concurrently with us. Make sure that anything after
4309     // this point does not assume that we are the only GC thread
4310     // running. Note: of course, the actual marking work will
4311     // not start until the safepoint itself is released in
4312     // SuspendibleThreadSet::desynchronize().
4313     doConcurrentMark();
4314   }
4315 
4316   return true;
4317 }
4318 
4319 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4320 {
4321   size_t gclab_word_size;
4322   switch (purpose) {
4323     case GCAllocForSurvived:
4324       gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4325       break;
4326     case GCAllocForTenured:
4327       gclab_word_size = _old_plab_stats.desired_plab_sz();
4328       break;
4329     default:
4330       assert(false, "unknown GCAllocPurpose");
4331       gclab_word_size = _old_plab_stats.desired_plab_sz();
4332       break;
4333   }
4334 
4335   // Prevent humongous PLAB sizes for two reasons:
4336   // * PLABs are allocated using a similar paths as oops, but should
4337   //   never be in a humongous region
4338   // * Allowing humongous PLABs needlessly churns the region free lists
4339   return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4340 }
4341 
4342 void G1CollectedHeap::init_mutator_alloc_region() {
4343   assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4344   _mutator_alloc_region.init();
4345 }
4346 
4347 void G1CollectedHeap::release_mutator_alloc_region() {
4348   _mutator_alloc_region.release();
4349   assert(_mutator_alloc_region.get() == NULL, "post-condition");
4350 }
4351 
4352 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4353   assert_at_safepoint(true /* should_be_vm_thread */);
4354 
4355   _survivor_gc_alloc_region.init();
4356   _old_gc_alloc_region.init();
4357   HeapRegion* retained_region = _retained_old_gc_alloc_region;
4358   _retained_old_gc_alloc_region = NULL;
4359 
4360   // We will discard the current GC alloc region if:
4361   // a) it's in the collection set (it can happen!),
4362   // b) it's already full (no point in using it),
4363   // c) it's empty (this means that it was emptied during
4364   // a cleanup and it should be on the free list now), or
4365   // d) it's humongous (this means that it was emptied
4366   // during a cleanup and was added to the free list, but
4367   // has been subsequently used to allocate a humongous
4368   // object that may be less than the region size).
4369   if (retained_region != NULL &&
4370       !retained_region->in_collection_set() &&
4371       !(retained_region->top() == retained_region->end()) &&
4372       !retained_region->is_empty() &&
4373       !retained_region->isHumongous()) {
4374     retained_region->set_saved_mark();
4375     // The retained region was added to the old region set when it was
4376     // retired. We have to remove it now, since we don't allow regions
4377     // we allocate to in the region sets. We'll re-add it later, when
4378     // it's retired again.
4379     _old_set.remove(retained_region);
4380     bool during_im = g1_policy()->during_initial_mark_pause();
4381     retained_region->note_start_of_copying(during_im);
4382     _old_gc_alloc_region.set(retained_region);
4383     _hr_printer.reuse(retained_region);
4384     evacuation_info.set_alloc_regions_used_before(retained_region->used());
4385   }
4386 }
4387 
4388 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4389   evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4390                                          _old_gc_alloc_region.count());
4391   _survivor_gc_alloc_region.release();
4392   // If we have an old GC alloc region to release, we'll save it in
4393   // _retained_old_gc_alloc_region. If we don't
4394   // _retained_old_gc_alloc_region will become NULL. This is what we
4395   // want either way so no reason to check explicitly for either
4396   // condition.
4397   _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4398 
4399   if (ResizePLAB) {
4400     _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4401     _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4402   }
4403 }
4404 
4405 void G1CollectedHeap::abandon_gc_alloc_regions() {
4406   assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4407   assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4408   _retained_old_gc_alloc_region = NULL;
4409 }
4410 
4411 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4412   _drain_in_progress = false;
4413   set_evac_failure_closure(cl);
4414   _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4415 }
4416 
4417 void G1CollectedHeap::finalize_for_evac_failure() {
4418   assert(_evac_failure_scan_stack != NULL &&
4419          _evac_failure_scan_stack->length() == 0,
4420          "Postcondition");
4421   assert(!_drain_in_progress, "Postcondition");
4422   delete _evac_failure_scan_stack;
4423   _evac_failure_scan_stack = NULL;
4424 }
4425 
4426 void G1CollectedHeap::remove_self_forwarding_pointers() {
4427   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4428 
4429   double remove_self_forwards_start = os::elapsedTime();
4430 
4431   G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4432 
4433   if (G1CollectedHeap::use_parallel_gc_threads()) {
4434     set_par_threads();
4435     workers()->run_task(&rsfp_task);
4436     set_par_threads(0);
4437   } else {
4438     rsfp_task.work(0);
4439   }
4440 
4441   assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4442 
4443   // Reset the claim values in the regions in the collection set.
4444   reset_cset_heap_region_claim_values();
4445 
4446   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4447 
4448   // Now restore saved marks, if any.
4449   assert(_objs_with_preserved_marks.size() ==
4450             _preserved_marks_of_objs.size(), "Both or none.");
4451   while (!_objs_with_preserved_marks.is_empty()) {
4452     oop obj = _objs_with_preserved_marks.pop();
4453     markOop m = _preserved_marks_of_objs.pop();
4454     obj->set_mark(m);
4455   }
4456   _objs_with_preserved_marks.clear(true);
4457   _preserved_marks_of_objs.clear(true);
4458 
4459   g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4460 }
4461 
4462 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4463   _evac_failure_scan_stack->push(obj);
4464 }
4465 
4466 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4467   assert(_evac_failure_scan_stack != NULL, "precondition");
4468 
4469   while (_evac_failure_scan_stack->length() > 0) {
4470      oop obj = _evac_failure_scan_stack->pop();
4471      _evac_failure_closure->set_region(heap_region_containing(obj));
4472      obj->oop_iterate_backwards(_evac_failure_closure);
4473   }
4474 }
4475 
4476 oop
4477 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4478                                                oop old) {
4479   assert(obj_in_cs(old),
4480          err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4481                  (HeapWord*) old));
4482   markOop m = old->mark();
4483   oop forward_ptr = old->forward_to_atomic(old);
4484   if (forward_ptr == NULL) {
4485     // Forward-to-self succeeded.
4486     assert(_par_scan_state != NULL, "par scan state");
4487     OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4488     uint queue_num = _par_scan_state->queue_num();
4489 
4490     _evacuation_failed = true;
4491     _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4492     if (_evac_failure_closure != cl) {
4493       MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4494       assert(!_drain_in_progress,
4495              "Should only be true while someone holds the lock.");
4496       // Set the global evac-failure closure to the current thread's.
4497       assert(_evac_failure_closure == NULL, "Or locking has failed.");
4498       set_evac_failure_closure(cl);
4499       // Now do the common part.
4500       handle_evacuation_failure_common(old, m);
4501       // Reset to NULL.
4502       set_evac_failure_closure(NULL);
4503     } else {
4504       // The lock is already held, and this is recursive.
4505       assert(_drain_in_progress, "This should only be the recursive case.");
4506       handle_evacuation_failure_common(old, m);
4507     }
4508     return old;
4509   } else {
4510     // Forward-to-self failed. Either someone else managed to allocate
4511     // space for this object (old != forward_ptr) or they beat us in
4512     // self-forwarding it (old == forward_ptr).
4513     assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4514            err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4515                    "should not be in the CSet",
4516                    (HeapWord*) old, (HeapWord*) forward_ptr));
4517     return forward_ptr;
4518   }
4519 }
4520 
4521 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4522   preserve_mark_if_necessary(old, m);
4523 
4524   HeapRegion* r = heap_region_containing(old);
4525   if (!r->evacuation_failed()) {
4526     r->set_evacuation_failed(true);
4527     _hr_printer.evac_failure(r);
4528   }
4529 
4530   push_on_evac_failure_scan_stack(old);
4531 
4532   if (!_drain_in_progress) {
4533     // prevent recursion in copy_to_survivor_space()
4534     _drain_in_progress = true;
4535     drain_evac_failure_scan_stack();
4536     _drain_in_progress = false;
4537   }
4538 }
4539 
4540 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4541   assert(evacuation_failed(), "Oversaving!");
4542   // We want to call the "for_promotion_failure" version only in the
4543   // case of a promotion failure.
4544   if (m->must_be_preserved_for_promotion_failure(obj)) {
4545     _objs_with_preserved_marks.push(obj);
4546     _preserved_marks_of_objs.push(m);
4547   }
4548 }
4549 
4550 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4551                                                   size_t word_size) {
4552   if (purpose == GCAllocForSurvived) {
4553     HeapWord* result = survivor_attempt_allocation(word_size);
4554     if (result != NULL) {
4555       return result;
4556     } else {
4557       // Let's try to allocate in the old gen in case we can fit the
4558       // object there.
4559       return old_attempt_allocation(word_size);
4560     }
4561   } else {
4562     assert(purpose ==  GCAllocForTenured, "sanity");
4563     HeapWord* result = old_attempt_allocation(word_size);
4564     if (result != NULL) {
4565       return result;
4566     } else {
4567       // Let's try to allocate in the survivors in case we can fit the
4568       // object there.
4569       return survivor_attempt_allocation(word_size);
4570     }
4571   }
4572 
4573   ShouldNotReachHere();
4574   // Trying to keep some compilers happy.
4575   return NULL;
4576 }
4577 
4578 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4579   ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4580 
4581 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4582   : _g1h(g1h),
4583     _refs(g1h->task_queue(queue_num)),
4584     _dcq(&g1h->dirty_card_queue_set()),
4585     _ct_bs(g1h->g1_barrier_set()),
4586     _g1_rem(g1h->g1_rem_set()),
4587     _hash_seed(17), _queue_num(queue_num),
4588     _term_attempts(0),
4589     _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4590     _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4591     _age_table(false), _scanner(g1h, this, rp),
4592     _strong_roots_time(0), _term_time(0),
4593     _alloc_buffer_waste(0), _undo_waste(0) {
4594   // we allocate G1YoungSurvRateNumRegions plus one entries, since
4595   // we "sacrifice" entry 0 to keep track of surviving bytes for
4596   // non-young regions (where the age is -1)
4597   // We also add a few elements at the beginning and at the end in
4598   // an attempt to eliminate cache contention
4599   uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4600   uint array_length = PADDING_ELEM_NUM +
4601                       real_length +
4602                       PADDING_ELEM_NUM;
4603   _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4604   if (_surviving_young_words_base == NULL)
4605     vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4606                           "Not enough space for young surv histo.");
4607   _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4608   memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4609 
4610   _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4611   _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;
4612 
4613   _start = os::elapsedTime();
4614 }
4615 
4616 void
4617 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4618 {
4619   st->print_raw_cr("GC Termination Stats");
4620   st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"
4621                    " ------waste (KiB)------");
4622   st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"
4623                    "  total   alloc    undo");
4624   st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4625                    " ------- ------- -------");
4626 }
4627 
4628 void
4629 G1ParScanThreadState::print_termination_stats(int i,
4630                                               outputStream* const st) const
4631 {
4632   const double elapsed_ms = elapsed_time() * 1000.0;
4633   const double s_roots_ms = strong_roots_time() * 1000.0;
4634   const double term_ms    = term_time() * 1000.0;
4635   st->print_cr("%3d %9.2f %9.2f %6.2f "
4636                "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4637                SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4638                i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4639                term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4640                (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4641                alloc_buffer_waste() * HeapWordSize / K,
4642                undo_waste() * HeapWordSize / K);
4643 }
4644 
4645 #ifdef ASSERT
4646 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4647   assert(ref != NULL, "invariant");
4648   assert(UseCompressedOops, "sanity");
4649   assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4650   oop p = oopDesc::load_decode_heap_oop(ref);
4651   assert(_g1h->is_in_g1_reserved(p),
4652          err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4653   return true;
4654 }
4655 
4656 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4657   assert(ref != NULL, "invariant");
4658   if (has_partial_array_mask(ref)) {
4659     // Must be in the collection set--it's already been copied.
4660     oop p = clear_partial_array_mask(ref);
4661     assert(_g1h->obj_in_cs(p),
4662            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4663   } else {
4664     oop p = oopDesc::load_decode_heap_oop(ref);
4665     assert(_g1h->is_in_g1_reserved(p),
4666            err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4667   }
4668   return true;
4669 }
4670 
4671 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4672   if (ref.is_narrow()) {
4673     return verify_ref((narrowOop*) ref);
4674   } else {
4675     return verify_ref((oop*) ref);
4676   }
4677 }
4678 #endif // ASSERT
4679 
4680 void G1ParScanThreadState::trim_queue() {
4681   assert(_evac_failure_cl != NULL, "not set");
4682 
4683   StarTask ref;
4684   do {
4685     // Drain the overflow stack first, so other threads can steal.
4686     while (refs()->pop_overflow(ref)) {
4687       deal_with_reference(ref);
4688     }
4689 
4690     while (refs()->pop_local(ref)) {
4691       deal_with_reference(ref);
4692     }
4693   } while (!refs()->is_empty());
4694 }
4695 
4696 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4697                                      G1ParScanThreadState* par_scan_state) :
4698   _g1(g1), _par_scan_state(par_scan_state),
4699   _worker_id(par_scan_state->queue_num()) { }
4700 
4701 void G1ParCopyHelper::mark_object(oop obj) {
4702   assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4703 
4704   // We know that the object is not moving so it's safe to read its size.
4705   _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4706 }
4707 
4708 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4709   assert(from_obj->is_forwarded(), "from obj should be forwarded");
4710   assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4711   assert(from_obj != to_obj, "should not be self-forwarded");
4712 
4713   assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4714   assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4715 
4716   // The object might be in the process of being copied by another
4717   // worker so we cannot trust that its to-space image is
4718   // well-formed. So we have to read its size from its from-space
4719   // image which we know should not be changing.
4720   _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4721 }
4722 
4723 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4724   size_t word_sz = old->size();
4725   HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4726   // +1 to make the -1 indexes valid...
4727   int       young_index = from_region->young_index_in_cset()+1;
4728   assert( (from_region->is_young() && young_index >  0) ||
4729          (!from_region->is_young() && young_index == 0), "invariant" );
4730   G1CollectorPolicy* g1p = _g1h->g1_policy();
4731   markOop m = old->mark();
4732   int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4733                                            : m->age();
4734   GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4735                                                              word_sz);
4736   HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4737 #ifndef PRODUCT
4738   // Should this evacuation fail?
4739   if (_g1h->evacuation_should_fail()) {
4740     if (obj_ptr != NULL) {
4741       undo_allocation(alloc_purpose, obj_ptr, word_sz);
4742       obj_ptr = NULL;
4743     }
4744   }
4745 #endif // !PRODUCT
4746 
4747   if (obj_ptr == NULL) {
4748     // This will either forward-to-self, or detect that someone else has
4749     // installed a forwarding pointer.
4750     return _g1h->handle_evacuation_failure_par(this, old);
4751   }
4752 
4753   oop obj = oop(obj_ptr);
4754 
4755   // We're going to allocate linearly, so might as well prefetch ahead.
4756   Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4757 
4758   oop forward_ptr = old->forward_to_atomic(obj);
4759   if (forward_ptr == NULL) {
4760     Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4761 
4762     // alloc_purpose is just a hint to allocate() above, recheck the type of region
4763     // we actually allocated from and update alloc_purpose accordingly
4764     HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4765     alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4766 
4767     if (g1p->track_object_age(alloc_purpose)) {
4768       // We could simply do obj->incr_age(). However, this causes a
4769       // performance issue. obj->incr_age() will first check whether
4770       // the object has a displaced mark by checking its mark word;
4771       // getting the mark word from the new location of the object
4772       // stalls. So, given that we already have the mark word and we
4773       // are about to install it anyway, it's better to increase the
4774       // age on the mark word, when the object does not have a
4775       // displaced mark word. We're not expecting many objects to have
4776       // a displaced marked word, so that case is not optimized
4777       // further (it could be...) and we simply call obj->incr_age().
4778 
4779       if (m->has_displaced_mark_helper()) {
4780         // in this case, we have to install the mark word first,
4781         // otherwise obj looks to be forwarded (the old mark word,
4782         // which contains the forward pointer, was copied)
4783         obj->set_mark(m);
4784         obj->incr_age();
4785       } else {
4786         m = m->incr_age();
4787         obj->set_mark(m);
4788       }
4789       age_table()->add(obj, word_sz);
4790     } else {
4791       obj->set_mark(m);
4792     }
4793 
4794     if (G1StringDedup::is_enabled()) {
4795       G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4796                                              to_region->is_young(),
4797                                              queue_num(),
4798                                              obj);
4799     }
4800 
4801     size_t* surv_young_words = surviving_young_words();
4802     surv_young_words[young_index] += word_sz;
4803 
4804     if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4805       // We keep track of the next start index in the length field of
4806       // the to-space object. The actual length can be found in the
4807       // length field of the from-space object.
4808       arrayOop(obj)->set_length(0);
4809       oop* old_p = set_partial_array_mask(old);
4810       push_on_queue(old_p);
4811     } else {
4812       // No point in using the slower heap_region_containing() method,
4813       // given that we know obj is in the heap.
4814       _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4815       obj->oop_iterate_backwards(&_scanner);
4816     }
4817   } else {
4818     undo_allocation(alloc_purpose, obj_ptr, word_sz);
4819     obj = forward_ptr;
4820   }
4821   return obj;
4822 }
4823 
4824 template <class T>
4825 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4826   if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4827     _scanned_klass->record_modified_oops();
4828   }
4829 }
4830 
4831 template <G1Barrier barrier, bool do_mark_object>
4832 template <class T>
4833 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4834   T heap_oop = oopDesc::load_heap_oop(p);
4835 
4836   if (oopDesc::is_null(heap_oop)) {
4837     return;
4838   }
4839 
4840   oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4841 
4842   assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4843 
4844   if (_g1->in_cset_fast_test(obj)) {
4845     oop forwardee;
4846     if (obj->is_forwarded()) {
4847       forwardee = obj->forwardee();
4848     } else {
4849       forwardee = _par_scan_state->copy_to_survivor_space(obj);
4850     }
4851     assert(forwardee != NULL, "forwardee should not be NULL");
4852     oopDesc::encode_store_heap_oop(p, forwardee);
4853     if (do_mark_object && forwardee != obj) {
4854       // If the object is self-forwarded we don't need to explicitly
4855       // mark it, the evacuation failure protocol will do so.
4856       mark_forwarded_object(obj, forwardee);
4857     }
4858 
4859     if (barrier == G1BarrierKlass) {
4860       do_klass_barrier(p, forwardee);
4861     }
4862   } else {
4863     // The object is not in collection set. If we're a root scanning
4864     // closure during an initial mark pause (i.e. do_mark_object will
4865     // be true) then attempt to mark the object.
4866     if (do_mark_object) {
4867       mark_object(obj);
4868     }
4869   }
4870 
4871   if (barrier == G1BarrierEvac) {
4872     _par_scan_state->update_rs(_from, p, _worker_id);
4873   }
4874 }
4875 
4876 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4877 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4878 
4879 class G1ParEvacuateFollowersClosure : public VoidClosure {
4880 protected:
4881   G1CollectedHeap*              _g1h;
4882   G1ParScanThreadState*         _par_scan_state;
4883   RefToScanQueueSet*            _queues;
4884   ParallelTaskTerminator*       _terminator;
4885 
4886   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
4887   RefToScanQueueSet*      queues()         { return _queues; }
4888   ParallelTaskTerminator* terminator()     { return _terminator; }
4889 
4890 public:
4891   G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4892                                 G1ParScanThreadState* par_scan_state,
4893                                 RefToScanQueueSet* queues,
4894                                 ParallelTaskTerminator* terminator)
4895     : _g1h(g1h), _par_scan_state(par_scan_state),
4896       _queues(queues), _terminator(terminator) {}
4897 
4898   void do_void();
4899 
4900 private:
4901   inline bool offer_termination();
4902 };
4903 
4904 bool G1ParEvacuateFollowersClosure::offer_termination() {
4905   G1ParScanThreadState* const pss = par_scan_state();
4906   pss->start_term_time();
4907   const bool res = terminator()->offer_termination();
4908   pss->end_term_time();
4909   return res;
4910 }
4911 
4912 void G1ParEvacuateFollowersClosure::do_void() {
4913   StarTask stolen_task;
4914   G1ParScanThreadState* const pss = par_scan_state();
4915   pss->trim_queue();
4916 
4917   do {
4918     while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4919       assert(pss->verify_task(stolen_task), "sanity");
4920       if (stolen_task.is_narrow()) {
4921         pss->deal_with_reference((narrowOop*) stolen_task);
4922       } else {
4923         pss->deal_with_reference((oop*) stolen_task);
4924       }
4925 
4926       // We've just processed a reference and we might have made
4927       // available new entries on the queues. So we have to make sure
4928       // we drain the queues as necessary.
4929       pss->trim_queue();
4930     }
4931   } while (!offer_termination());
4932 }
4933 
4934 class G1KlassScanClosure : public KlassClosure {
4935  G1ParCopyHelper* _closure;
4936  bool             _process_only_dirty;
4937  int              _count;
4938  public:
4939   G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4940       : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4941   void do_klass(Klass* klass) {
4942     // If the klass has not been dirtied we know that there's
4943     // no references into  the young gen and we can skip it.
4944    if (!_process_only_dirty || klass->has_modified_oops()) {
4945       // Clean the klass since we're going to scavenge all the metadata.
4946       klass->clear_modified_oops();
4947 
4948       // Tell the closure that this klass is the Klass to scavenge
4949       // and is the one to dirty if oops are left pointing into the young gen.
4950       _closure->set_scanned_klass(klass);
4951 
4952       klass->oops_do(_closure);
4953 
4954       _closure->set_scanned_klass(NULL);
4955     }
4956     _count++;
4957   }
4958 };
4959 
4960 class G1ParTask : public AbstractGangTask {
4961 protected:
4962   G1CollectedHeap*       _g1h;
4963   RefToScanQueueSet      *_queues;
4964   ParallelTaskTerminator _terminator;
4965   uint _n_workers;
4966 
4967   Mutex _stats_lock;
4968   Mutex* stats_lock() { return &_stats_lock; }
4969 
4970   size_t getNCards() {
4971     return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4972       / G1BlockOffsetSharedArray::N_bytes;
4973   }
4974 
4975 public:
4976   G1ParTask(G1CollectedHeap* g1h,
4977             RefToScanQueueSet *task_queues)
4978     : AbstractGangTask("G1 collection"),
4979       _g1h(g1h),
4980       _queues(task_queues),
4981       _terminator(0, _queues),
4982       _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4983   {}
4984 
4985   RefToScanQueueSet* queues() { return _queues; }
4986 
4987   RefToScanQueue *work_queue(int i) {
4988     return queues()->queue(i);
4989   }
4990 
4991   ParallelTaskTerminator* terminator() { return &_terminator; }
4992 
4993   virtual void set_for_termination(int active_workers) {
4994     // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4995     // in the young space (_par_seq_tasks) in the G1 heap
4996     // for SequentialSubTasksDone.
4997     // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4998     // both of which need setting by set_n_termination().
4999     _g1h->SharedHeap::set_n_termination(active_workers);
5000     _g1h->set_n_termination(active_workers);
5001     terminator()->reset_for_reuse(active_workers);
5002     _n_workers = active_workers;
5003   }
5004 
5005   void work(uint worker_id) {
5006     if (worker_id >= _n_workers) return;  // no work needed this round
5007 
5008     double start_time_ms = os::elapsedTime() * 1000.0;
5009     _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5010 
5011     {
5012       ResourceMark rm;
5013       HandleMark   hm;
5014 
5015       ReferenceProcessor*             rp = _g1h->ref_processor_stw();
5016 
5017       G1ParScanThreadState            pss(_g1h, worker_id, rp);
5018       G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5019 
5020       pss.set_evac_failure_closure(&evac_failure_cl);
5021 
5022       G1ParScanExtRootClosure        only_scan_root_cl(_g1h, &pss, rp);
5023       G1ParScanMetadataClosure       only_scan_metadata_cl(_g1h, &pss, rp);
5024 
5025       G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5026       G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5027 
5028       bool only_young                 = _g1h->g1_policy()->gcs_are_young();
5029       G1KlassScanClosure              scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5030       G1KlassScanClosure              only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5031 
5032       OopClosure*                    scan_root_cl = &only_scan_root_cl;
5033       G1KlassScanClosure*            scan_klasses_cl = &only_scan_klasses_cl_s;
5034 
5035       if (_g1h->g1_policy()->during_initial_mark_pause()) {
5036         // We also need to mark copied objects.
5037         scan_root_cl = &scan_mark_root_cl;
5038         scan_klasses_cl = &scan_mark_klasses_cl_s;
5039       }
5040 
5041       G1ParPushHeapRSClosure          push_heap_rs_cl(_g1h, &pss);
5042 
5043       // Don't scan the scavengable methods in the code cache as part
5044       // of strong root scanning. The code roots that point into a
5045       // region in the collection set are scanned when we scan the
5046       // region's RSet.
5047       int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5048 
5049       pss.start_strong_roots();
5050       _g1h->g1_process_strong_roots(/* is scavenging */ true,
5051                                     SharedHeap::ScanningOption(so),
5052                                     scan_root_cl,
5053                                     &push_heap_rs_cl,
5054                                     scan_klasses_cl,
5055                                     worker_id);
5056       pss.end_strong_roots();
5057 
5058       {
5059         double start = os::elapsedTime();
5060         G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5061         evac.do_void();
5062         double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5063         double term_ms = pss.term_time()*1000.0;
5064         _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5065         _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5066       }
5067       _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5068       _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5069 
5070       if (ParallelGCVerbose) {
5071         MutexLocker x(stats_lock());
5072         pss.print_termination_stats(worker_id);
5073       }
5074 
5075       assert(pss.refs()->is_empty(), "should be empty");
5076 
5077       // Close the inner scope so that the ResourceMark and HandleMark
5078       // destructors are executed here and are included as part of the
5079       // "GC Worker Time".
5080     }
5081 
5082     double end_time_ms = os::elapsedTime() * 1000.0;
5083     _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5084   }
5085 };
5086 
5087 // *** Common G1 Evacuation Stuff
5088 
5089 // This method is run in a GC worker.
5090 
5091 void
5092 G1CollectedHeap::
5093 g1_process_strong_roots(bool is_scavenging,
5094                         ScanningOption so,
5095                         OopClosure* scan_non_heap_roots,
5096                         OopsInHeapRegionClosure* scan_rs,
5097                         G1KlassScanClosure* scan_klasses,
5098                         uint worker_i) {
5099 
5100   // First scan the strong roots
5101   double ext_roots_start = os::elapsedTime();
5102   double closure_app_time_sec = 0.0;
5103 
5104   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5105 
5106   process_strong_roots(false, // no scoping; this is parallel code
5107                        so,
5108                        &buf_scan_non_heap_roots,
5109                        scan_klasses
5110                        );
5111 
5112   // Now the CM ref_processor roots.
5113   if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5114     // We need to treat the discovered reference lists of the
5115     // concurrent mark ref processor as roots and keep entries
5116     // (which are added by the marking threads) on them live
5117     // until they can be processed at the end of marking.
5118     ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5119   }
5120 
5121   // Finish up any enqueued closure apps (attributed as object copy time).
5122   buf_scan_non_heap_roots.done();
5123 
5124   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5125 
5126   g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5127 
5128   double ext_root_time_ms =
5129     ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5130 
5131   g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5132 
5133   // During conc marking we have to filter the per-thread SATB buffers
5134   // to make sure we remove any oops into the CSet (which will show up
5135   // as implicitly live).
5136   double satb_filtering_ms = 0.0;
5137   if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5138     if (mark_in_progress()) {
5139       double satb_filter_start = os::elapsedTime();
5140 
5141       JavaThread::satb_mark_queue_set().filter_thread_buffers();
5142 
5143       satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5144     }
5145   }
5146   g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5147 
5148   // If this is an initial mark pause, and we're not scanning
5149   // the entire code cache, we need to mark the oops in the
5150   // strong code root lists for the regions that are not in
5151   // the collection set.
5152   // Note all threads participate in this set of root tasks.
5153   double mark_strong_code_roots_ms = 0.0;
5154   if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5155     double mark_strong_roots_start = os::elapsedTime();
5156     mark_strong_code_roots(worker_i);
5157     mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5158   }
5159   g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5160 
5161   // Now scan the complement of the collection set.
5162   CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5163   g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5164 
5165   _process_strong_tasks->all_tasks_completed();
5166 }
5167 
5168 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5169 private:
5170   BoolObjectClosure* _is_alive;
5171   int _initial_string_table_size;
5172   int _initial_symbol_table_size;
5173 
5174   bool  _process_strings;
5175   int _strings_processed;
5176   int _strings_removed;
5177 
5178   bool  _process_symbols;
5179   int _symbols_processed;
5180   int _symbols_removed;
5181 
5182   bool _do_in_parallel;
5183 public:
5184   G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5185     AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5186     _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5187     _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5188     _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5189 
5190     _initial_string_table_size = StringTable::the_table()->table_size();
5191     _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5192     if (process_strings) {
5193       StringTable::clear_parallel_claimed_index();
5194     }
5195     if (process_symbols) {
5196       SymbolTable::clear_parallel_claimed_index();
5197     }
5198   }
5199 
5200   ~G1StringSymbolTableUnlinkTask() {
5201     guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5202               err_msg("claim value %d after unlink less than initial string table size %d",
5203                       StringTable::parallel_claimed_index(), _initial_string_table_size));
5204     guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5205               err_msg("claim value %d after unlink less than initial symbol table size %d",
5206                       SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5207   }
5208 
5209   void work(uint worker_id) {
5210     if (_do_in_parallel) {
5211       int strings_processed = 0;
5212       int strings_removed = 0;
5213       int symbols_processed = 0;
5214       int symbols_removed = 0;
5215       if (_process_strings) {
5216         StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5217         Atomic::add(strings_processed, &_strings_processed);
5218         Atomic::add(strings_removed, &_strings_removed);
5219       }
5220       if (_process_symbols) {
5221         SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5222         Atomic::add(symbols_processed, &_symbols_processed);
5223         Atomic::add(symbols_removed, &_symbols_removed);
5224       }
5225     } else {
5226       if (_process_strings) {
5227         StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5228       }
5229       if (_process_symbols) {
5230         SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5231       }
5232     }
5233   }
5234 
5235   size_t strings_processed() const { return (size_t)_strings_processed; }
5236   size_t strings_removed()   const { return (size_t)_strings_removed; }
5237 
5238   size_t symbols_processed() const { return (size_t)_symbols_processed; }
5239   size_t symbols_removed()   const { return (size_t)_symbols_removed; }
5240 };
5241 
5242 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5243                                                      bool process_strings, bool process_symbols) {
5244   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5245                    _g1h->workers()->active_workers() : 1);
5246 
5247   G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5248   if (G1CollectedHeap::use_parallel_gc_threads()) {
5249     set_par_threads(n_workers);
5250     workers()->run_task(&g1_unlink_task);
5251     set_par_threads(0);
5252   } else {
5253     g1_unlink_task.work(0);
5254   }
5255   if (G1TraceStringSymbolTableScrubbing) {
5256     gclog_or_tty->print_cr("Cleaned string and symbol table, "
5257                            "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5258                            "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5259                            g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5260                            g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5261   }
5262 
5263   if (G1StringDedup::is_enabled()) {
5264     G1StringDedup::unlink(is_alive);
5265   }
5266 }
5267 
5268 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5269  private:
5270   DirtyCardQueueSet* _queue;
5271  public:
5272   G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5273 
5274   virtual void work(uint worker_id) {
5275     double start_time = os::elapsedTime();
5276 
5277     RedirtyLoggedCardTableEntryClosure cl;
5278     if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5279       _queue->par_apply_closure_to_all_completed_buffers(&cl);
5280     } else {
5281       _queue->apply_closure_to_all_completed_buffers(&cl);
5282     }
5283 
5284     G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5285     timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5286     timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5287   }
5288 };
5289 
5290 void G1CollectedHeap::redirty_logged_cards() {
5291   guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5292   double redirty_logged_cards_start = os::elapsedTime();
5293 
5294   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5295                    _g1h->workers()->active_workers() : 1);
5296 
5297   G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5298   dirty_card_queue_set().reset_for_par_iteration();
5299   if (use_parallel_gc_threads()) {
5300     set_par_threads(n_workers);
5301     workers()->run_task(&redirty_task);
5302     set_par_threads(0);
5303   } else {
5304     redirty_task.work(0);
5305   }
5306 
5307   DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5308   dcq.merge_bufferlists(&dirty_card_queue_set());
5309   assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5310 
5311   g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5312 }
5313 
5314 // Weak Reference Processing support
5315 
5316 // An always "is_alive" closure that is used to preserve referents.
5317 // If the object is non-null then it's alive.  Used in the preservation
5318 // of referent objects that are pointed to by reference objects
5319 // discovered by the CM ref processor.
5320 class G1AlwaysAliveClosure: public BoolObjectClosure {
5321   G1CollectedHeap* _g1;
5322 public:
5323   G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5324   bool do_object_b(oop p) {
5325     if (p != NULL) {
5326       return true;
5327     }
5328     return false;
5329   }
5330 };
5331 
5332 bool G1STWIsAliveClosure::do_object_b(oop p) {
5333   // An object is reachable if it is outside the collection set,
5334   // or is inside and copied.
5335   return !_g1->obj_in_cs(p) || p->is_forwarded();
5336 }
5337 
5338 // Non Copying Keep Alive closure
5339 class G1KeepAliveClosure: public OopClosure {
5340   G1CollectedHeap* _g1;
5341 public:
5342   G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5343   void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5344   void do_oop(      oop* p) {
5345     oop obj = *p;
5346 
5347     if (_g1->obj_in_cs(obj)) {
5348       assert( obj->is_forwarded(), "invariant" );
5349       *p = obj->forwardee();
5350     }
5351   }
5352 };
5353 
5354 // Copying Keep Alive closure - can be called from both
5355 // serial and parallel code as long as different worker
5356 // threads utilize different G1ParScanThreadState instances
5357 // and different queues.
5358 
5359 class G1CopyingKeepAliveClosure: public OopClosure {
5360   G1CollectedHeap*         _g1h;
5361   OopClosure*              _copy_non_heap_obj_cl;
5362   OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5363   G1ParScanThreadState*    _par_scan_state;
5364 
5365 public:
5366   G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5367                             OopClosure* non_heap_obj_cl,
5368                             OopsInHeapRegionClosure* metadata_obj_cl,
5369                             G1ParScanThreadState* pss):
5370     _g1h(g1h),
5371     _copy_non_heap_obj_cl(non_heap_obj_cl),
5372     _copy_metadata_obj_cl(metadata_obj_cl),
5373     _par_scan_state(pss)
5374   {}
5375 
5376   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5377   virtual void do_oop(      oop* p) { do_oop_work(p); }
5378 
5379   template <class T> void do_oop_work(T* p) {
5380     oop obj = oopDesc::load_decode_heap_oop(p);
5381 
5382     if (_g1h->obj_in_cs(obj)) {
5383       // If the referent object has been forwarded (either copied
5384       // to a new location or to itself in the event of an
5385       // evacuation failure) then we need to update the reference
5386       // field and, if both reference and referent are in the G1
5387       // heap, update the RSet for the referent.
5388       //
5389       // If the referent has not been forwarded then we have to keep
5390       // it alive by policy. Therefore we have copy the referent.
5391       //
5392       // If the reference field is in the G1 heap then we can push
5393       // on the PSS queue. When the queue is drained (after each
5394       // phase of reference processing) the object and it's followers
5395       // will be copied, the reference field set to point to the
5396       // new location, and the RSet updated. Otherwise we need to
5397       // use the the non-heap or metadata closures directly to copy
5398       // the referent object and update the pointer, while avoiding
5399       // updating the RSet.
5400 
5401       if (_g1h->is_in_g1_reserved(p)) {
5402         _par_scan_state->push_on_queue(p);
5403       } else {
5404         assert(!ClassLoaderDataGraph::contains((address)p),
5405                err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5406                               PTR_FORMAT, p));
5407           _copy_non_heap_obj_cl->do_oop(p);
5408         }
5409       }
5410     }
5411 };
5412 
5413 // Serial drain queue closure. Called as the 'complete_gc'
5414 // closure for each discovered list in some of the
5415 // reference processing phases.
5416 
5417 class G1STWDrainQueueClosure: public VoidClosure {
5418 protected:
5419   G1CollectedHeap* _g1h;
5420   G1ParScanThreadState* _par_scan_state;
5421 
5422   G1ParScanThreadState*   par_scan_state() { return _par_scan_state; }
5423 
5424 public:
5425   G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5426     _g1h(g1h),
5427     _par_scan_state(pss)
5428   { }
5429 
5430   void do_void() {
5431     G1ParScanThreadState* const pss = par_scan_state();
5432     pss->trim_queue();
5433   }
5434 };
5435 
5436 // Parallel Reference Processing closures
5437 
5438 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5439 // processing during G1 evacuation pauses.
5440 
5441 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5442 private:
5443   G1CollectedHeap*   _g1h;
5444   RefToScanQueueSet* _queues;
5445   FlexibleWorkGang*  _workers;
5446   int                _active_workers;
5447 
5448 public:
5449   G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5450                         FlexibleWorkGang* workers,
5451                         RefToScanQueueSet *task_queues,
5452                         int n_workers) :
5453     _g1h(g1h),
5454     _queues(task_queues),
5455     _workers(workers),
5456     _active_workers(n_workers)
5457   {
5458     assert(n_workers > 0, "shouldn't call this otherwise");
5459   }
5460 
5461   // Executes the given task using concurrent marking worker threads.
5462   virtual void execute(ProcessTask& task);
5463   virtual void execute(EnqueueTask& task);
5464 };
5465 
5466 // Gang task for possibly parallel reference processing
5467 
5468 class G1STWRefProcTaskProxy: public AbstractGangTask {
5469   typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5470   ProcessTask&     _proc_task;
5471   G1CollectedHeap* _g1h;
5472   RefToScanQueueSet *_task_queues;
5473   ParallelTaskTerminator* _terminator;
5474 
5475 public:
5476   G1STWRefProcTaskProxy(ProcessTask& proc_task,
5477                      G1CollectedHeap* g1h,
5478                      RefToScanQueueSet *task_queues,
5479                      ParallelTaskTerminator* terminator) :
5480     AbstractGangTask("Process reference objects in parallel"),
5481     _proc_task(proc_task),
5482     _g1h(g1h),
5483     _task_queues(task_queues),
5484     _terminator(terminator)
5485   {}
5486 
5487   virtual void work(uint worker_id) {
5488     // The reference processing task executed by a single worker.
5489     ResourceMark rm;
5490     HandleMark   hm;
5491 
5492     G1STWIsAliveClosure is_alive(_g1h);
5493 
5494     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5495     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5496 
5497     pss.set_evac_failure_closure(&evac_failure_cl);
5498 
5499     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5500     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5501 
5502     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5503     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5504 
5505     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5506     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5507 
5508     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5509       // We also need to mark copied objects.
5510       copy_non_heap_cl = &copy_mark_non_heap_cl;
5511       copy_metadata_cl = &copy_mark_metadata_cl;
5512     }
5513 
5514     // Keep alive closure.
5515     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5516 
5517     // Complete GC closure
5518     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5519 
5520     // Call the reference processing task's work routine.
5521     _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5522 
5523     // Note we cannot assert that the refs array is empty here as not all
5524     // of the processing tasks (specifically phase2 - pp2_work) execute
5525     // the complete_gc closure (which ordinarily would drain the queue) so
5526     // the queue may not be empty.
5527   }
5528 };
5529 
5530 // Driver routine for parallel reference processing.
5531 // Creates an instance of the ref processing gang
5532 // task and has the worker threads execute it.
5533 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5534   assert(_workers != NULL, "Need parallel worker threads.");
5535 
5536   ParallelTaskTerminator terminator(_active_workers, _queues);
5537   G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5538 
5539   _g1h->set_par_threads(_active_workers);
5540   _workers->run_task(&proc_task_proxy);
5541   _g1h->set_par_threads(0);
5542 }
5543 
5544 // Gang task for parallel reference enqueueing.
5545 
5546 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5547   typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5548   EnqueueTask& _enq_task;
5549 
5550 public:
5551   G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5552     AbstractGangTask("Enqueue reference objects in parallel"),
5553     _enq_task(enq_task)
5554   { }
5555 
5556   virtual void work(uint worker_id) {
5557     _enq_task.work(worker_id);
5558   }
5559 };
5560 
5561 // Driver routine for parallel reference enqueueing.
5562 // Creates an instance of the ref enqueueing gang
5563 // task and has the worker threads execute it.
5564 
5565 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5566   assert(_workers != NULL, "Need parallel worker threads.");
5567 
5568   G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5569 
5570   _g1h->set_par_threads(_active_workers);
5571   _workers->run_task(&enq_task_proxy);
5572   _g1h->set_par_threads(0);
5573 }
5574 
5575 // End of weak reference support closures
5576 
5577 // Abstract task used to preserve (i.e. copy) any referent objects
5578 // that are in the collection set and are pointed to by reference
5579 // objects discovered by the CM ref processor.
5580 
5581 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5582 protected:
5583   G1CollectedHeap* _g1h;
5584   RefToScanQueueSet      *_queues;
5585   ParallelTaskTerminator _terminator;
5586   uint _n_workers;
5587 
5588 public:
5589   G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5590     AbstractGangTask("ParPreserveCMReferents"),
5591     _g1h(g1h),
5592     _queues(task_queues),
5593     _terminator(workers, _queues),
5594     _n_workers(workers)
5595   { }
5596 
5597   void work(uint worker_id) {
5598     ResourceMark rm;
5599     HandleMark   hm;
5600 
5601     G1ParScanThreadState            pss(_g1h, worker_id, NULL);
5602     G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5603 
5604     pss.set_evac_failure_closure(&evac_failure_cl);
5605 
5606     assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5607 
5608 
5609     G1ParScanExtRootClosure        only_copy_non_heap_cl(_g1h, &pss, NULL);
5610     G1ParScanMetadataClosure       only_copy_metadata_cl(_g1h, &pss, NULL);
5611 
5612     G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5613     G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5614 
5615     OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5616     OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5617 
5618     if (_g1h->g1_policy()->during_initial_mark_pause()) {
5619       // We also need to mark copied objects.
5620       copy_non_heap_cl = &copy_mark_non_heap_cl;
5621       copy_metadata_cl = &copy_mark_metadata_cl;
5622     }
5623 
5624     // Is alive closure
5625     G1AlwaysAliveClosure always_alive(_g1h);
5626 
5627     // Copying keep alive closure. Applied to referent objects that need
5628     // to be copied.
5629     G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5630 
5631     ReferenceProcessor* rp = _g1h->ref_processor_cm();
5632 
5633     uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5634     uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5635 
5636     // limit is set using max_num_q() - which was set using ParallelGCThreads.
5637     // So this must be true - but assert just in case someone decides to
5638     // change the worker ids.
5639     assert(0 <= worker_id && worker_id < limit, "sanity");
5640     assert(!rp->discovery_is_atomic(), "check this code");
5641 
5642     // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5643     for (uint idx = worker_id; idx < limit; idx += stride) {
5644       DiscoveredList& ref_list = rp->discovered_refs()[idx];
5645 
5646       DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5647       while (iter.has_next()) {
5648         // Since discovery is not atomic for the CM ref processor, we
5649         // can see some null referent objects.
5650         iter.load_ptrs(DEBUG_ONLY(true));
5651         oop ref = iter.obj();
5652 
5653         // This will filter nulls.
5654         if (iter.is_referent_alive()) {
5655           iter.make_referent_alive();
5656         }
5657         iter.move_to_next();
5658       }
5659     }
5660 
5661     // Drain the queue - which may cause stealing
5662     G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5663     drain_queue.do_void();
5664     // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5665     assert(pss.refs()->is_empty(), "should be");
5666   }
5667 };
5668 
5669 // Weak Reference processing during an evacuation pause (part 1).
5670 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5671   double ref_proc_start = os::elapsedTime();
5672 
5673   ReferenceProcessor* rp = _ref_processor_stw;
5674   assert(rp->discovery_enabled(), "should have been enabled");
5675 
5676   // Any reference objects, in the collection set, that were 'discovered'
5677   // by the CM ref processor should have already been copied (either by
5678   // applying the external root copy closure to the discovered lists, or
5679   // by following an RSet entry).
5680   //
5681   // But some of the referents, that are in the collection set, that these
5682   // reference objects point to may not have been copied: the STW ref
5683   // processor would have seen that the reference object had already
5684   // been 'discovered' and would have skipped discovering the reference,
5685   // but would not have treated the reference object as a regular oop.
5686   // As a result the copy closure would not have been applied to the
5687   // referent object.
5688   //
5689   // We need to explicitly copy these referent objects - the references
5690   // will be processed at the end of remarking.
5691   //
5692   // We also need to do this copying before we process the reference
5693   // objects discovered by the STW ref processor in case one of these
5694   // referents points to another object which is also referenced by an
5695   // object discovered by the STW ref processor.
5696 
5697   assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5698            no_of_gc_workers == workers()->active_workers(),
5699            "Need to reset active GC workers");
5700 
5701   set_par_threads(no_of_gc_workers);
5702   G1ParPreserveCMReferentsTask keep_cm_referents(this,
5703                                                  no_of_gc_workers,
5704                                                  _task_queues);
5705 
5706   if (G1CollectedHeap::use_parallel_gc_threads()) {
5707     workers()->run_task(&keep_cm_referents);
5708   } else {
5709     keep_cm_referents.work(0);
5710   }
5711 
5712   set_par_threads(0);
5713 
5714   // Closure to test whether a referent is alive.
5715   G1STWIsAliveClosure is_alive(this);
5716 
5717   // Even when parallel reference processing is enabled, the processing
5718   // of JNI refs is serial and performed serially by the current thread
5719   // rather than by a worker. The following PSS will be used for processing
5720   // JNI refs.
5721 
5722   // Use only a single queue for this PSS.
5723   G1ParScanThreadState            pss(this, 0, NULL);
5724 
5725   // We do not embed a reference processor in the copying/scanning
5726   // closures while we're actually processing the discovered
5727   // reference objects.
5728   G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5729 
5730   pss.set_evac_failure_closure(&evac_failure_cl);
5731 
5732   assert(pss.refs()->is_empty(), "pre-condition");
5733 
5734   G1ParScanExtRootClosure        only_copy_non_heap_cl(this, &pss, NULL);
5735   G1ParScanMetadataClosure       only_copy_metadata_cl(this, &pss, NULL);
5736 
5737   G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5738   G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5739 
5740   OopClosure*                    copy_non_heap_cl = &only_copy_non_heap_cl;
5741   OopsInHeapRegionClosure*       copy_metadata_cl = &only_copy_metadata_cl;
5742 
5743   if (_g1h->g1_policy()->during_initial_mark_pause()) {
5744     // We also need to mark copied objects.
5745     copy_non_heap_cl = &copy_mark_non_heap_cl;
5746     copy_metadata_cl = &copy_mark_metadata_cl;
5747   }
5748 
5749   // Keep alive closure.
5750   G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5751 
5752   // Serial Complete GC closure
5753   G1STWDrainQueueClosure drain_queue(this, &pss);
5754 
5755   // Setup the soft refs policy...
5756   rp->setup_policy(false);
5757 
5758   ReferenceProcessorStats stats;
5759   if (!rp->processing_is_mt()) {
5760     // Serial reference processing...
5761     stats = rp->process_discovered_references(&is_alive,
5762                                               &keep_alive,
5763                                               &drain_queue,
5764                                               NULL,
5765                                               _gc_timer_stw);
5766   } else {
5767     // Parallel reference processing
5768     assert(rp->num_q() == no_of_gc_workers, "sanity");
5769     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5770 
5771     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5772     stats = rp->process_discovered_references(&is_alive,
5773                                               &keep_alive,
5774                                               &drain_queue,
5775                                               &par_task_executor,
5776                                               _gc_timer_stw);
5777   }
5778 
5779   _gc_tracer_stw->report_gc_reference_stats(stats);
5780 
5781   // We have completed copying any necessary live referent objects.
5782   assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5783 
5784   double ref_proc_time = os::elapsedTime() - ref_proc_start;
5785   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5786 }
5787 
5788 // Weak Reference processing during an evacuation pause (part 2).
5789 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5790   double ref_enq_start = os::elapsedTime();
5791 
5792   ReferenceProcessor* rp = _ref_processor_stw;
5793   assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5794 
5795   // Now enqueue any remaining on the discovered lists on to
5796   // the pending list.
5797   if (!rp->processing_is_mt()) {
5798     // Serial reference processing...
5799     rp->enqueue_discovered_references();
5800   } else {
5801     // Parallel reference enqueueing
5802 
5803     assert(no_of_gc_workers == workers()->active_workers(),
5804            "Need to reset active workers");
5805     assert(rp->num_q() == no_of_gc_workers, "sanity");
5806     assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5807 
5808     G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5809     rp->enqueue_discovered_references(&par_task_executor);
5810   }
5811 
5812   rp->verify_no_references_recorded();
5813   assert(!rp->discovery_enabled(), "should have been disabled");
5814 
5815   // FIXME
5816   // CM's reference processing also cleans up the string and symbol tables.
5817   // Should we do that here also? We could, but it is a serial operation
5818   // and could significantly increase the pause time.
5819 
5820   double ref_enq_time = os::elapsedTime() - ref_enq_start;
5821   g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5822 }
5823 
5824 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5825   _expand_heap_after_alloc_failure = true;
5826   _evacuation_failed = false;
5827 
5828   // Should G1EvacuationFailureALot be in effect for this GC?
5829   NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5830 
5831   g1_rem_set()->prepare_for_oops_into_collection_set_do();
5832 
5833   // Disable the hot card cache.
5834   G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5835   hot_card_cache->reset_hot_cache_claimed_index();
5836   hot_card_cache->set_use_cache(false);
5837 
5838   uint n_workers;
5839   if (G1CollectedHeap::use_parallel_gc_threads()) {
5840     n_workers =
5841       AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5842                                      workers()->active_workers(),
5843                                      Threads::number_of_non_daemon_threads());
5844     assert(UseDynamicNumberOfGCThreads ||
5845            n_workers == workers()->total_workers(),
5846            "If not dynamic should be using all the  workers");
5847     workers()->set_active_workers(n_workers);
5848     set_par_threads(n_workers);
5849   } else {
5850     assert(n_par_threads() == 0,
5851            "Should be the original non-parallel value");
5852     n_workers = 1;
5853   }
5854 
5855   G1ParTask g1_par_task(this, _task_queues);
5856 
5857   init_for_evac_failure(NULL);
5858 
5859   rem_set()->prepare_for_younger_refs_iterate(true);
5860 
5861   assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5862   double start_par_time_sec = os::elapsedTime();
5863   double end_par_time_sec;
5864 
5865   {
5866     StrongRootsScope srs(this);
5867 
5868     if (G1CollectedHeap::use_parallel_gc_threads()) {
5869       // The individual threads will set their evac-failure closures.
5870       if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5871       // These tasks use ShareHeap::_process_strong_tasks
5872       assert(UseDynamicNumberOfGCThreads ||
5873              workers()->active_workers() == workers()->total_workers(),
5874              "If not dynamic should be using all the  workers");
5875       workers()->run_task(&g1_par_task);
5876     } else {
5877       g1_par_task.set_for_termination(n_workers);
5878       g1_par_task.work(0);
5879     }
5880     end_par_time_sec = os::elapsedTime();
5881 
5882     // Closing the inner scope will execute the destructor
5883     // for the StrongRootsScope object. We record the current
5884     // elapsed time before closing the scope so that time
5885     // taken for the SRS destructor is NOT included in the
5886     // reported parallel time.
5887   }
5888 
5889   double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5890   g1_policy()->phase_times()->record_par_time(par_time_ms);
5891 
5892   double code_root_fixup_time_ms =
5893         (os::elapsedTime() - end_par_time_sec) * 1000.0;
5894   g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5895 
5896   set_par_threads(0);
5897 
5898   // Process any discovered reference objects - we have
5899   // to do this _before_ we retire the GC alloc regions
5900   // as we may have to copy some 'reachable' referent
5901   // objects (and their reachable sub-graphs) that were
5902   // not copied during the pause.
5903   process_discovered_references(n_workers);
5904 
5905   // Weak root processing.
5906   {
5907     G1STWIsAliveClosure is_alive(this);
5908     G1KeepAliveClosure keep_alive(this);
5909     JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5910     if (G1StringDedup::is_enabled()) {
5911       G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5912     }
5913   }
5914 
5915   release_gc_alloc_regions(n_workers, evacuation_info);
5916   g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5917 
5918   // Reset and re-enable the hot card cache.
5919   // Note the counts for the cards in the regions in the
5920   // collection set are reset when the collection set is freed.
5921   hot_card_cache->reset_hot_cache();
5922   hot_card_cache->set_use_cache(true);
5923 
5924   // Migrate the strong code roots attached to each region in
5925   // the collection set. Ideally we would like to do this
5926   // after we have finished the scanning/evacuation of the
5927   // strong code roots for a particular heap region.
5928   migrate_strong_code_roots();
5929 
5930   purge_code_root_memory();
5931 
5932   if (g1_policy()->during_initial_mark_pause()) {
5933     // Reset the claim values set during marking the strong code roots
5934     reset_heap_region_claim_values();
5935   }
5936 
5937   finalize_for_evac_failure();
5938 
5939   if (evacuation_failed()) {
5940     remove_self_forwarding_pointers();
5941 
5942     // Reset the G1EvacuationFailureALot counters and flags
5943     // Note: the values are reset only when an actual
5944     // evacuation failure occurs.
5945     NOT_PRODUCT(reset_evacuation_should_fail();)
5946   }
5947 
5948   // Enqueue any remaining references remaining on the STW
5949   // reference processor's discovered lists. We need to do
5950   // this after the card table is cleaned (and verified) as
5951   // the act of enqueueing entries on to the pending list
5952   // will log these updates (and dirty their associated
5953   // cards). We need these updates logged to update any
5954   // RSets.
5955   enqueue_discovered_references(n_workers);
5956 
5957   if (G1DeferredRSUpdate) {
5958     redirty_logged_cards();
5959   }
5960   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5961 }
5962 
5963 void G1CollectedHeap::free_region(HeapRegion* hr,
5964                                   FreeRegionList* free_list,
5965                                   bool par,
5966                                   bool locked) {
5967   assert(!hr->isHumongous(), "this is only for non-humongous regions");
5968   assert(!hr->is_empty(), "the region should not be empty");
5969   assert(free_list != NULL, "pre-condition");
5970 
5971   if (G1VerifyBitmaps) {
5972     MemRegion mr(hr->bottom(), hr->end());
5973     concurrent_mark()->clearRangePrevBitmap(mr);
5974   }
5975 
5976   // Clear the card counts for this region.
5977   // Note: we only need to do this if the region is not young
5978   // (since we don't refine cards in young regions).
5979   if (!hr->is_young()) {
5980     _cg1r->hot_card_cache()->reset_card_counts(hr);
5981   }
5982   hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5983   free_list->add_ordered(hr);
5984 }
5985 
5986 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5987                                      FreeRegionList* free_list,
5988                                      bool par) {
5989   assert(hr->startsHumongous(), "this is only for starts humongous regions");
5990   assert(free_list != NULL, "pre-condition");
5991 
5992   size_t hr_capacity = hr->capacity();
5993   // We need to read this before we make the region non-humongous,
5994   // otherwise the information will be gone.
5995   uint last_index = hr->last_hc_index();
5996   hr->set_notHumongous();
5997   free_region(hr, free_list, par);
5998 
5999   uint i = hr->hrs_index() + 1;
6000   while (i < last_index) {
6001     HeapRegion* curr_hr = region_at(i);
6002     assert(curr_hr->continuesHumongous(), "invariant");
6003     curr_hr->set_notHumongous();
6004     free_region(curr_hr, free_list, par);
6005     i += 1;
6006   }
6007 }
6008 
6009 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6010                                        const HeapRegionSetCount& humongous_regions_removed) {
6011   if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6012     MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6013     _old_set.bulk_remove(old_regions_removed);
6014     _humongous_set.bulk_remove(humongous_regions_removed);
6015   }
6016 
6017 }
6018 
6019 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6020   assert(list != NULL, "list can't be null");
6021   if (!list->is_empty()) {
6022     MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6023     _free_list.add_ordered(list);
6024   }
6025 }
6026 
6027 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6028   assert(_summary_bytes_used >= bytes,
6029          err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6030                   _summary_bytes_used, bytes));
6031   _summary_bytes_used -= bytes;
6032 }
6033 
6034 class G1ParCleanupCTTask : public AbstractGangTask {
6035   G1SATBCardTableModRefBS* _ct_bs;
6036   G1CollectedHeap* _g1h;
6037   HeapRegion* volatile _su_head;
6038 public:
6039   G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6040                      G1CollectedHeap* g1h) :
6041     AbstractGangTask("G1 Par Cleanup CT Task"),
6042     _ct_bs(ct_bs), _g1h(g1h) { }
6043 
6044   void work(uint worker_id) {
6045     HeapRegion* r;
6046     while (r = _g1h->pop_dirty_cards_region()) {
6047       clear_cards(r);
6048     }
6049   }
6050 
6051   void clear_cards(HeapRegion* r) {
6052     // Cards of the survivors should have already been dirtied.
6053     if (!r->is_survivor()) {
6054       _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6055     }
6056   }
6057 };
6058 
6059 #ifndef PRODUCT
6060 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6061   G1CollectedHeap* _g1h;
6062   G1SATBCardTableModRefBS* _ct_bs;
6063 public:
6064   G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6065     : _g1h(g1h), _ct_bs(ct_bs) { }
6066   virtual bool doHeapRegion(HeapRegion* r) {
6067     if (r->is_survivor()) {
6068       _g1h->verify_dirty_region(r);
6069     } else {
6070       _g1h->verify_not_dirty_region(r);
6071     }
6072     return false;
6073   }
6074 };
6075 
6076 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6077   // All of the region should be clean.
6078   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6079   MemRegion mr(hr->bottom(), hr->end());
6080   ct_bs->verify_not_dirty_region(mr);
6081 }
6082 
6083 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6084   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
6085   // dirty allocated blocks as they allocate them. The thread that
6086   // retires each region and replaces it with a new one will do a
6087   // maximal allocation to fill in [pre_dummy_top(),end()] but will
6088   // not dirty that area (one less thing to have to do while holding
6089   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6090   // is dirty.
6091   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6092   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6093   if (hr->is_young()) {
6094     ct_bs->verify_g1_young_region(mr);
6095   } else {
6096     ct_bs->verify_dirty_region(mr);
6097   }
6098 }
6099 
6100 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6101   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6102   for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6103     verify_dirty_region(hr);
6104   }
6105 }
6106 
6107 void G1CollectedHeap::verify_dirty_young_regions() {
6108   verify_dirty_young_list(_young_list->first_region());
6109 }
6110 
6111 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6112                                                HeapWord* tams, HeapWord* end) {
6113   guarantee(tams <= end,
6114             err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6115   HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6116   if (result < end) {
6117     gclog_or_tty->cr();
6118     gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6119                            bitmap_name, result);
6120     gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6121                            bitmap_name, tams, end);
6122     return false;
6123   }
6124   return true;
6125 }
6126 
6127 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6128   CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6129   CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6130 
6131   HeapWord* bottom = hr->bottom();
6132   HeapWord* ptams  = hr->prev_top_at_mark_start();
6133   HeapWord* ntams  = hr->next_top_at_mark_start();
6134   HeapWord* end    = hr->end();
6135 
6136   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6137 
6138   bool res_n = true;
6139   // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6140   // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6141   // if we happen to be in that state.
6142   if (mark_in_progress() || !_cmThread->in_progress()) {
6143     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6144   }
6145   if (!res_p || !res_n) {
6146     gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6147                            HR_FORMAT_PARAMS(hr));
6148     gclog_or_tty->print_cr("#### Caller: %s", caller);
6149     return false;
6150   }
6151   return true;
6152 }
6153 
6154 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6155   if (!G1VerifyBitmaps) return;
6156 
6157   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6158 }
6159 
6160 class G1VerifyBitmapClosure : public HeapRegionClosure {
6161 private:
6162   const char* _caller;
6163   G1CollectedHeap* _g1h;
6164   bool _failures;
6165 
6166 public:
6167   G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6168     _caller(caller), _g1h(g1h), _failures(false) { }
6169 
6170   bool failures() { return _failures; }
6171 
6172   virtual bool doHeapRegion(HeapRegion* hr) {
6173     if (hr->continuesHumongous()) return false;
6174 
6175     bool result = _g1h->verify_bitmaps(_caller, hr);
6176     if (!result) {
6177       _failures = true;
6178     }
6179     return false;
6180   }
6181 };
6182 
6183 void G1CollectedHeap::check_bitmaps(const char* caller) {
6184   if (!G1VerifyBitmaps) return;
6185 
6186   G1VerifyBitmapClosure cl(caller, this);
6187   heap_region_iterate(&cl);
6188   guarantee(!cl.failures(), "bitmap verification");
6189 }
6190 #endif // PRODUCT
6191 
6192 void G1CollectedHeap::cleanUpCardTable() {
6193   G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6194   double start = os::elapsedTime();
6195 
6196   {
6197     // Iterate over the dirty cards region list.
6198     G1ParCleanupCTTask cleanup_task(ct_bs, this);
6199 
6200     if (G1CollectedHeap::use_parallel_gc_threads()) {
6201       set_par_threads();
6202       workers()->run_task(&cleanup_task);
6203       set_par_threads(0);
6204     } else {
6205       while (_dirty_cards_region_list) {
6206         HeapRegion* r = _dirty_cards_region_list;
6207         cleanup_task.clear_cards(r);
6208         _dirty_cards_region_list = r->get_next_dirty_cards_region();
6209         if (_dirty_cards_region_list == r) {
6210           // The last region.
6211           _dirty_cards_region_list = NULL;
6212         }
6213         r->set_next_dirty_cards_region(NULL);
6214       }
6215     }
6216 #ifndef PRODUCT
6217     if (G1VerifyCTCleanup || VerifyAfterGC) {
6218       G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6219       heap_region_iterate(&cleanup_verifier);
6220     }
6221 #endif
6222   }
6223 
6224   double elapsed = os::elapsedTime() - start;
6225   g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6226 }
6227 
6228 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6229   size_t pre_used = 0;
6230   FreeRegionList local_free_list("Local List for CSet Freeing");
6231 
6232   double young_time_ms     = 0.0;
6233   double non_young_time_ms = 0.0;
6234 
6235   // Since the collection set is a superset of the the young list,
6236   // all we need to do to clear the young list is clear its
6237   // head and length, and unlink any young regions in the code below
6238   _young_list->clear();
6239 
6240   G1CollectorPolicy* policy = g1_policy();
6241 
6242   double start_sec = os::elapsedTime();
6243   bool non_young = true;
6244 
6245   HeapRegion* cur = cs_head;
6246   int age_bound = -1;
6247   size_t rs_lengths = 0;
6248 
6249   while (cur != NULL) {
6250     assert(!is_on_master_free_list(cur), "sanity");
6251     if (non_young) {
6252       if (cur->is_young()) {
6253         double end_sec = os::elapsedTime();
6254         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6255         non_young_time_ms += elapsed_ms;
6256 
6257         start_sec = os::elapsedTime();
6258         non_young = false;
6259       }
6260     } else {
6261       if (!cur->is_young()) {
6262         double end_sec = os::elapsedTime();
6263         double elapsed_ms = (end_sec - start_sec) * 1000.0;
6264         young_time_ms += elapsed_ms;
6265 
6266         start_sec = os::elapsedTime();
6267         non_young = true;
6268       }
6269     }
6270 
6271     rs_lengths += cur->rem_set()->occupied_locked();
6272 
6273     HeapRegion* next = cur->next_in_collection_set();
6274     assert(cur->in_collection_set(), "bad CS");
6275     cur->set_next_in_collection_set(NULL);
6276     cur->set_in_collection_set(false);
6277 
6278     if (cur->is_young()) {
6279       int index = cur->young_index_in_cset();
6280       assert(index != -1, "invariant");
6281       assert((uint) index < policy->young_cset_region_length(), "invariant");
6282       size_t words_survived = _surviving_young_words[index];
6283       cur->record_surv_words_in_group(words_survived);
6284 
6285       // At this point the we have 'popped' cur from the collection set
6286       // (linked via next_in_collection_set()) but it is still in the
6287       // young list (linked via next_young_region()). Clear the
6288       // _next_young_region field.
6289       cur->set_next_young_region(NULL);
6290     } else {
6291       int index = cur->young_index_in_cset();
6292       assert(index == -1, "invariant");
6293     }
6294 
6295     assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6296             (!cur->is_young() && cur->young_index_in_cset() == -1),
6297             "invariant" );
6298 
6299     if (!cur->evacuation_failed()) {
6300       MemRegion used_mr = cur->used_region();
6301 
6302       // And the region is empty.
6303       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6304       pre_used += cur->used();
6305       free_region(cur, &local_free_list, false /* par */, true /* locked */);
6306     } else {
6307       cur->uninstall_surv_rate_group();
6308       if (cur->is_young()) {
6309         cur->set_young_index_in_cset(-1);
6310       }
6311       cur->set_not_young();
6312       cur->set_evacuation_failed(false);
6313       // The region is now considered to be old.
6314       _old_set.add(cur);
6315       evacuation_info.increment_collectionset_used_after(cur->used());
6316     }
6317     cur = next;
6318   }
6319 
6320   evacuation_info.set_regions_freed(local_free_list.length());
6321   policy->record_max_rs_lengths(rs_lengths);
6322   policy->cset_regions_freed();
6323 
6324   double end_sec = os::elapsedTime();
6325   double elapsed_ms = (end_sec - start_sec) * 1000.0;
6326 
6327   if (non_young) {
6328     non_young_time_ms += elapsed_ms;
6329   } else {
6330     young_time_ms += elapsed_ms;
6331   }
6332 
6333   prepend_to_freelist(&local_free_list);
6334   decrement_summary_bytes(pre_used);
6335   policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6336   policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6337 }
6338 
6339 // This routine is similar to the above but does not record
6340 // any policy statistics or update free lists; we are abandoning
6341 // the current incremental collection set in preparation of a
6342 // full collection. After the full GC we will start to build up
6343 // the incremental collection set again.
6344 // This is only called when we're doing a full collection
6345 // and is immediately followed by the tearing down of the young list.
6346 
6347 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6348   HeapRegion* cur = cs_head;
6349 
6350   while (cur != NULL) {
6351     HeapRegion* next = cur->next_in_collection_set();
6352     assert(cur->in_collection_set(), "bad CS");
6353     cur->set_next_in_collection_set(NULL);
6354     cur->set_in_collection_set(false);
6355     cur->set_young_index_in_cset(-1);
6356     cur = next;
6357   }
6358 }
6359 
6360 void G1CollectedHeap::set_free_regions_coming() {
6361   if (G1ConcRegionFreeingVerbose) {
6362     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6363                            "setting free regions coming");
6364   }
6365 
6366   assert(!free_regions_coming(), "pre-condition");
6367   _free_regions_coming = true;
6368 }
6369 
6370 void G1CollectedHeap::reset_free_regions_coming() {
6371   assert(free_regions_coming(), "pre-condition");
6372 
6373   {
6374     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6375     _free_regions_coming = false;
6376     SecondaryFreeList_lock->notify_all();
6377   }
6378 
6379   if (G1ConcRegionFreeingVerbose) {
6380     gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6381                            "reset free regions coming");
6382   }
6383 }
6384 
6385 void G1CollectedHeap::wait_while_free_regions_coming() {
6386   // Most of the time we won't have to wait, so let's do a quick test
6387   // first before we take the lock.
6388   if (!free_regions_coming()) {
6389     return;
6390   }
6391 
6392   if (G1ConcRegionFreeingVerbose) {
6393     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6394                            "waiting for free regions");
6395   }
6396 
6397   {
6398     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6399     while (free_regions_coming()) {
6400       SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6401     }
6402   }
6403 
6404   if (G1ConcRegionFreeingVerbose) {
6405     gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6406                            "done waiting for free regions");
6407   }
6408 }
6409 
6410 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6411   assert(heap_lock_held_for_gc(),
6412               "the heap lock should already be held by or for this thread");
6413   _young_list->push_region(hr);
6414 }
6415 
6416 class NoYoungRegionsClosure: public HeapRegionClosure {
6417 private:
6418   bool _success;
6419 public:
6420   NoYoungRegionsClosure() : _success(true) { }
6421   bool doHeapRegion(HeapRegion* r) {
6422     if (r->is_young()) {
6423       gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6424                              r->bottom(), r->end());
6425       _success = false;
6426     }
6427     return false;
6428   }
6429   bool success() { return _success; }
6430 };
6431 
6432 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6433   bool ret = _young_list->check_list_empty(check_sample);
6434 
6435   if (check_heap) {
6436     NoYoungRegionsClosure closure;
6437     heap_region_iterate(&closure);
6438     ret = ret && closure.success();
6439   }
6440 
6441   return ret;
6442 }
6443 
6444 class TearDownRegionSetsClosure : public HeapRegionClosure {
6445 private:
6446   HeapRegionSet *_old_set;
6447 
6448 public:
6449   TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6450 
6451   bool doHeapRegion(HeapRegion* r) {
6452     if (r->is_empty()) {
6453       // We ignore empty regions, we'll empty the free list afterwards
6454     } else if (r->is_young()) {
6455       // We ignore young regions, we'll empty the young list afterwards
6456     } else if (r->isHumongous()) {
6457       // We ignore humongous regions, we're not tearing down the
6458       // humongous region set
6459     } else {
6460       // The rest should be old
6461       _old_set->remove(r);
6462     }
6463     return false;
6464   }
6465 
6466   ~TearDownRegionSetsClosure() {
6467     assert(_old_set->is_empty(), "post-condition");
6468   }
6469 };
6470 
6471 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6472   assert_at_safepoint(true /* should_be_vm_thread */);
6473 
6474   if (!free_list_only) {
6475     TearDownRegionSetsClosure cl(&_old_set);
6476     heap_region_iterate(&cl);
6477 
6478     // Note that emptying the _young_list is postponed and instead done as
6479     // the first step when rebuilding the regions sets again. The reason for
6480     // this is that during a full GC string deduplication needs to know if
6481     // a collected region was young or old when the full GC was initiated.
6482   }
6483   _free_list.remove_all();
6484 }
6485 
6486 class RebuildRegionSetsClosure : public HeapRegionClosure {
6487 private:
6488   bool            _free_list_only;
6489   HeapRegionSet*   _old_set;
6490   FreeRegionList* _free_list;
6491   size_t          _total_used;
6492 
6493 public:
6494   RebuildRegionSetsClosure(bool free_list_only,
6495                            HeapRegionSet* old_set, FreeRegionList* free_list) :
6496     _free_list_only(free_list_only),
6497     _old_set(old_set), _free_list(free_list), _total_used(0) {
6498     assert(_free_list->is_empty(), "pre-condition");
6499     if (!free_list_only) {
6500       assert(_old_set->is_empty(), "pre-condition");
6501     }
6502   }
6503 
6504   bool doHeapRegion(HeapRegion* r) {
6505     if (r->continuesHumongous()) {
6506       return false;
6507     }
6508 
6509     if (r->is_empty()) {
6510       // Add free regions to the free list
6511       _free_list->add_as_tail(r);
6512     } else if (!_free_list_only) {
6513       assert(!r->is_young(), "we should not come across young regions");
6514 
6515       if (r->isHumongous()) {
6516         // We ignore humongous regions, we left the humongous set unchanged
6517       } else {
6518         // The rest should be old, add them to the old set
6519         _old_set->add(r);
6520       }
6521       _total_used += r->used();
6522     }
6523 
6524     return false;
6525   }
6526 
6527   size_t total_used() {
6528     return _total_used;
6529   }
6530 };
6531 
6532 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6533   assert_at_safepoint(true /* should_be_vm_thread */);
6534 
6535   if (!free_list_only) {
6536     _young_list->empty_list();
6537   }
6538 
6539   RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6540   heap_region_iterate(&cl);
6541 
6542   if (!free_list_only) {
6543     _summary_bytes_used = cl.total_used();
6544   }
6545   assert(_summary_bytes_used == recalculate_used(),
6546          err_msg("inconsistent _summary_bytes_used, "
6547                  "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6548                  _summary_bytes_used, recalculate_used()));
6549 }
6550 
6551 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6552   _refine_cte_cl->set_concurrent(concurrent);
6553 }
6554 
6555 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6556   HeapRegion* hr = heap_region_containing(p);
6557   return hr->is_in(p);
6558 }
6559 
6560 // Methods for the mutator alloc region
6561 
6562 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6563                                                       bool force) {
6564   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6565   assert(!force || g1_policy()->can_expand_young_list(),
6566          "if force is true we should be able to expand the young list");
6567   bool young_list_full = g1_policy()->is_young_list_full();
6568   if (force || !young_list_full) {
6569     HeapRegion* new_alloc_region = new_region(word_size,
6570                                               false /* is_old */,
6571                                               false /* do_expand */);
6572     if (new_alloc_region != NULL) {
6573       set_region_short_lived_locked(new_alloc_region);
6574       _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6575       check_bitmaps("Mutator Region Allocation", new_alloc_region);
6576       return new_alloc_region;
6577     }
6578   }
6579   return NULL;
6580 }
6581 
6582 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6583                                                   size_t allocated_bytes) {
6584   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6585   assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6586 
6587   g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6588   _summary_bytes_used += allocated_bytes;
6589   _hr_printer.retire(alloc_region);
6590   // We update the eden sizes here, when the region is retired,
6591   // instead of when it's allocated, since this is the point that its
6592   // used space has been recored in _summary_bytes_used.
6593   g1mm()->update_eden_size();
6594 }
6595 
6596 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6597                                                     bool force) {
6598   return _g1h->new_mutator_alloc_region(word_size, force);
6599 }
6600 
6601 void G1CollectedHeap::set_par_threads() {
6602   // Don't change the number of workers.  Use the value previously set
6603   // in the workgroup.
6604   assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6605   uint n_workers = workers()->active_workers();
6606   assert(UseDynamicNumberOfGCThreads ||
6607            n_workers == workers()->total_workers(),
6608       "Otherwise should be using the total number of workers");
6609   if (n_workers == 0) {
6610     assert(false, "Should have been set in prior evacuation pause.");
6611     n_workers = ParallelGCThreads;
6612     workers()->set_active_workers(n_workers);
6613   }
6614   set_par_threads(n_workers);
6615 }
6616 
6617 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6618                                        size_t allocated_bytes) {
6619   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6620 }
6621 
6622 // Methods for the GC alloc regions
6623 
6624 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6625                                                  uint count,
6626                                                  GCAllocPurpose ap) {
6627   assert(FreeList_lock->owned_by_self(), "pre-condition");
6628 
6629   if (count < g1_policy()->max_regions(ap)) {
6630     bool survivor = (ap == GCAllocForSurvived);
6631     HeapRegion* new_alloc_region = new_region(word_size,
6632                                               !survivor,
6633                                               true /* do_expand */);
6634     if (new_alloc_region != NULL) {
6635       // We really only need to do this for old regions given that we
6636       // should never scan survivors. But it doesn't hurt to do it
6637       // for survivors too.
6638       new_alloc_region->set_saved_mark();
6639       if (survivor) {
6640         new_alloc_region->set_survivor();
6641         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6642         check_bitmaps("Survivor Region Allocation", new_alloc_region);
6643       } else {
6644         _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6645         check_bitmaps("Old Region Allocation", new_alloc_region);
6646       }
6647       bool during_im = g1_policy()->during_initial_mark_pause();
6648       new_alloc_region->note_start_of_copying(during_im);
6649       return new_alloc_region;
6650     } else {
6651       g1_policy()->note_alloc_region_limit_reached(ap);
6652     }
6653   }
6654   return NULL;
6655 }
6656 
6657 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6658                                              size_t allocated_bytes,
6659                                              GCAllocPurpose ap) {
6660   bool during_im = g1_policy()->during_initial_mark_pause();
6661   alloc_region->note_end_of_copying(during_im);
6662   g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6663   if (ap == GCAllocForSurvived) {
6664     young_list()->add_survivor_region(alloc_region);
6665   } else {
6666     _old_set.add(alloc_region);
6667   }
6668   _hr_printer.retire(alloc_region);
6669 }
6670 
6671 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6672                                                        bool force) {
6673   assert(!force, "not supported for GC alloc regions");
6674   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6675 }
6676 
6677 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6678                                           size_t allocated_bytes) {
6679   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6680                                GCAllocForSurvived);
6681 }
6682 
6683 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6684                                                   bool force) {
6685   assert(!force, "not supported for GC alloc regions");
6686   return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6687 }
6688 
6689 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6690                                      size_t allocated_bytes) {
6691   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6692                                GCAllocForTenured);
6693 }
6694 // Heap region set verification
6695 
6696 class VerifyRegionListsClosure : public HeapRegionClosure {
6697 private:
6698   HeapRegionSet*   _old_set;
6699   HeapRegionSet*   _humongous_set;
6700   FreeRegionList*  _free_list;
6701 
6702 public:
6703   HeapRegionSetCount _old_count;
6704   HeapRegionSetCount _humongous_count;
6705   HeapRegionSetCount _free_count;
6706 
6707   VerifyRegionListsClosure(HeapRegionSet* old_set,
6708                            HeapRegionSet* humongous_set,
6709                            FreeRegionList* free_list) :
6710     _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6711     _old_count(), _humongous_count(), _free_count(){ }
6712 
6713   bool doHeapRegion(HeapRegion* hr) {
6714     if (hr->continuesHumongous()) {
6715       return false;
6716     }
6717 
6718     if (hr->is_young()) {
6719       // TODO
6720     } else if (hr->startsHumongous()) {
6721       assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
6722       _humongous_count.increment(1u, hr->capacity());
6723     } else if (hr->is_empty()) {
6724       assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
6725       _free_count.increment(1u, hr->capacity());
6726     } else {
6727       assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
6728       _old_count.increment(1u, hr->capacity());
6729     }
6730     return false;
6731   }
6732 
6733   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6734     guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6735     guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6736         old_set->total_capacity_bytes(), _old_count.capacity()));
6737 
6738     guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6739     guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6740         humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6741 
6742     guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6743     guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6744         free_list->total_capacity_bytes(), _free_count.capacity()));
6745   }
6746 };
6747 
6748 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6749                                              HeapWord* bottom) {
6750   HeapWord* end = bottom + HeapRegion::GrainWords;
6751   MemRegion mr(bottom, end);
6752   assert(_g1_reserved.contains(mr), "invariant");
6753   // This might return NULL if the allocation fails
6754   return new HeapRegion(hrs_index, _bot_shared, mr);
6755 }
6756 
6757 void G1CollectedHeap::verify_region_sets() {
6758   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6759 
6760   // First, check the explicit lists.
6761   _free_list.verify_list();
6762   {
6763     // Given that a concurrent operation might be adding regions to
6764     // the secondary free list we have to take the lock before
6765     // verifying it.
6766     MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6767     _secondary_free_list.verify_list();
6768   }
6769 
6770   // If a concurrent region freeing operation is in progress it will
6771   // be difficult to correctly attributed any free regions we come
6772   // across to the correct free list given that they might belong to
6773   // one of several (free_list, secondary_free_list, any local lists,
6774   // etc.). So, if that's the case we will skip the rest of the
6775   // verification operation. Alternatively, waiting for the concurrent
6776   // operation to complete will have a non-trivial effect on the GC's
6777   // operation (no concurrent operation will last longer than the
6778   // interval between two calls to verification) and it might hide
6779   // any issues that we would like to catch during testing.
6780   if (free_regions_coming()) {
6781     return;
6782   }
6783 
6784   // Make sure we append the secondary_free_list on the free_list so
6785   // that all free regions we will come across can be safely
6786   // attributed to the free_list.
6787   append_secondary_free_list_if_not_empty_with_lock();
6788 
6789   // Finally, make sure that the region accounting in the lists is
6790   // consistent with what we see in the heap.
6791 
6792   VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6793   heap_region_iterate(&cl);
6794   cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6795 }
6796 
6797 // Optimized nmethod scanning
6798 
6799 class RegisterNMethodOopClosure: public OopClosure {
6800   G1CollectedHeap* _g1h;
6801   nmethod* _nm;
6802 
6803   template <class T> void do_oop_work(T* p) {
6804     T heap_oop = oopDesc::load_heap_oop(p);
6805     if (!oopDesc::is_null(heap_oop)) {
6806       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6807       HeapRegion* hr = _g1h->heap_region_containing(obj);
6808       assert(!hr->continuesHumongous(),
6809              err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6810                      " starting at "HR_FORMAT,
6811                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6812 
6813       // HeapRegion::add_strong_code_root() avoids adding duplicate
6814       // entries but having duplicates is  OK since we "mark" nmethods
6815       // as visited when we scan the strong code root lists during the GC.
6816       hr->add_strong_code_root(_nm);
6817       assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6818              err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6819                      _nm, HR_FORMAT_PARAMS(hr)));
6820     }
6821   }
6822 
6823 public:
6824   RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6825     _g1h(g1h), _nm(nm) {}
6826 
6827   void do_oop(oop* p)       { do_oop_work(p); }
6828   void do_oop(narrowOop* p) { do_oop_work(p); }
6829 };
6830 
6831 class UnregisterNMethodOopClosure: public OopClosure {
6832   G1CollectedHeap* _g1h;
6833   nmethod* _nm;
6834 
6835   template <class T> void do_oop_work(T* p) {
6836     T heap_oop = oopDesc::load_heap_oop(p);
6837     if (!oopDesc::is_null(heap_oop)) {
6838       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6839       HeapRegion* hr = _g1h->heap_region_containing(obj);
6840       assert(!hr->continuesHumongous(),
6841              err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6842                      " starting at "HR_FORMAT,
6843                      _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6844 
6845       hr->remove_strong_code_root(_nm);
6846       assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6847              err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6848                      _nm, HR_FORMAT_PARAMS(hr)));
6849     }
6850   }
6851 
6852 public:
6853   UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6854     _g1h(g1h), _nm(nm) {}
6855 
6856   void do_oop(oop* p)       { do_oop_work(p); }
6857   void do_oop(narrowOop* p) { do_oop_work(p); }
6858 };
6859 
6860 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6861   CollectedHeap::register_nmethod(nm);
6862 
6863   guarantee(nm != NULL, "sanity");
6864   RegisterNMethodOopClosure reg_cl(this, nm);
6865   nm->oops_do(&reg_cl);
6866 }
6867 
6868 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6869   CollectedHeap::unregister_nmethod(nm);
6870 
6871   guarantee(nm != NULL, "sanity");
6872   UnregisterNMethodOopClosure reg_cl(this, nm);
6873   nm->oops_do(&reg_cl, true);
6874 }
6875 
6876 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6877 public:
6878   bool doHeapRegion(HeapRegion *hr) {
6879     assert(!hr->isHumongous(),
6880            err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6881                    HR_FORMAT_PARAMS(hr)));
6882     hr->migrate_strong_code_roots();
6883     return false;
6884   }
6885 };
6886 
6887 void G1CollectedHeap::migrate_strong_code_roots() {
6888   MigrateCodeRootsHeapRegionClosure cl;
6889   double migrate_start = os::elapsedTime();
6890   collection_set_iterate(&cl);
6891   double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6892   g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6893 }
6894 
6895 void G1CollectedHeap::purge_code_root_memory() {
6896   double purge_start = os::elapsedTime();
6897   G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6898   double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6899   g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6900 }
6901 
6902 // Mark all the code roots that point into regions *not* in the
6903 // collection set.
6904 //
6905 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6906 // walking the the code roots lists of regions not in the collection
6907 // set. Suppose we have an nmethod (M) that points to objects in two
6908 // separate regions - one in the collection set (R1) and one not (R2).
6909 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6910 // nmethod M when walking the code roots for R1. When we come to scan
6911 // the code roots for R2, we would see that M is already marked and it
6912 // would be skipped and the objects in R2 that are referenced from M
6913 // would not be evacuated.
6914 
6915 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6916 
6917   class MarkStrongCodeRootOopClosure: public OopClosure {
6918     ConcurrentMark* _cm;
6919     HeapRegion* _hr;
6920     uint _worker_id;
6921 
6922     template <class T> void do_oop_work(T* p) {
6923       T heap_oop = oopDesc::load_heap_oop(p);
6924       if (!oopDesc::is_null(heap_oop)) {
6925         oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6926         // Only mark objects in the region (which is assumed
6927         // to be not in the collection set).
6928         if (_hr->is_in(obj)) {
6929           _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6930         }
6931       }
6932     }
6933 
6934   public:
6935     MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6936       _cm(cm), _hr(hr), _worker_id(worker_id) {
6937       assert(!_hr->in_collection_set(), "sanity");
6938     }
6939 
6940     void do_oop(narrowOop* p) { do_oop_work(p); }
6941     void do_oop(oop* p)       { do_oop_work(p); }
6942   };
6943 
6944   MarkStrongCodeRootOopClosure _oop_cl;
6945 
6946 public:
6947   MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6948     _oop_cl(cm, hr, worker_id) {}
6949 
6950   void do_code_blob(CodeBlob* cb) {
6951     nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6952     if (nm != NULL) {
6953       nm->oops_do(&_oop_cl);
6954     }
6955   }
6956 };
6957 
6958 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6959   G1CollectedHeap* _g1h;
6960   uint _worker_id;
6961 
6962 public:
6963   MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6964     _g1h(g1h), _worker_id(worker_id) {}
6965 
6966   bool doHeapRegion(HeapRegion *hr) {
6967     HeapRegionRemSet* hrrs = hr->rem_set();
6968     if (hr->continuesHumongous()) {
6969       // Code roots should never be attached to a continuation of a humongous region
6970       assert(hrrs->strong_code_roots_list_length() == 0,
6971              err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6972                      " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6973                      HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6974                      hrrs->strong_code_roots_list_length()));
6975       return false;
6976     }
6977 
6978     if (hr->in_collection_set()) {
6979       // Don't mark code roots into regions in the collection set here.
6980       // They will be marked when we scan them.
6981       return false;
6982     }
6983 
6984     MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6985     hr->strong_code_roots_do(&cb_cl);
6986     return false;
6987   }
6988 };
6989 
6990 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6991   MarkStrongCodeRootsHRClosure cl(this, worker_id);
6992   if (G1CollectedHeap::use_parallel_gc_threads()) {
6993     heap_region_par_iterate_chunked(&cl,
6994                                     worker_id,
6995                                     workers()->active_workers(),
6996                                     HeapRegion::ParMarkRootClaimValue);
6997   } else {
6998     heap_region_iterate(&cl);
6999   }
7000 }
7001 
7002 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
7003   G1CollectedHeap* _g1h;
7004 
7005 public:
7006   RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7007     _g1h(g1h) {}
7008 
7009   void do_code_blob(CodeBlob* cb) {
7010     nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7011     if (nm == NULL) {
7012       return;
7013     }
7014 
7015     if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
7016       _g1h->register_nmethod(nm);
7017     }
7018   }
7019 };
7020 
7021 void G1CollectedHeap::rebuild_strong_code_roots() {
7022   RebuildStrongCodeRootClosure blob_cl(this);
7023   CodeCache::blobs_do(&blob_cl);
7024 }