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