1 /*
2 * Copyright (c) 2001, 2015, 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 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess.
27 #endif
28
29 #include "precompiled.hpp"
30 #include "classfile/metadataOnStackMark.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/icBuffer.hpp"
33 #include "gc_implementation/g1/bufferingOopClosure.hpp"
34 #include "gc_implementation/g1/concurrentG1Refine.hpp"
35 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
36 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
37 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
38 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
39 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
40 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
41 #include "gc_implementation/g1/g1EvacFailure.hpp"
42 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
43 #include "gc_implementation/g1/g1Log.hpp"
44 #include "gc_implementation/g1/g1MarkSweep.hpp"
45 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
46 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
47 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
48 #include "gc_implementation/g1/g1RemSet.inline.hpp"
49 #include "gc_implementation/g1/g1RootProcessor.hpp"
50 #include "gc_implementation/g1/g1StringDedup.hpp"
51 #include "gc_implementation/g1/g1YCTypes.hpp"
52 #include "gc_implementation/g1/heapRegion.inline.hpp"
53 #include "gc_implementation/g1/heapRegionRemSet.hpp"
54 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
55 #include "gc_implementation/g1/vm_operations_g1.hpp"
56 #include "gc_implementation/shared/gcHeapSummary.hpp"
57 #include "gc_implementation/shared/gcTimer.hpp"
58 #include "gc_implementation/shared/gcTrace.hpp"
59 #include "gc_implementation/shared/gcTraceTime.hpp"
60 #include "gc_implementation/shared/isGCActiveMark.hpp"
61 #include "memory/allocation.hpp"
62 #include "memory/gcLocker.inline.hpp"
63 #include "memory/generationSpec.hpp"
64 #include "memory/iterator.hpp"
65 #include "memory/referenceProcessor.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "oops/oop.pcgc.inline.hpp"
68 #include "runtime/orderAccess.inline.hpp"
69 #include "runtime/vmThread.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 // Local to this file.
90
91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
92 bool _concurrent;
93 public:
94 RefineCardTableEntryClosure() : _concurrent(true) { }
95
96 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
97 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
98 // This path is executed by the concurrent refine or mutator threads,
99 // concurrently, and so we do not care if card_ptr contains references
100 // that point into the collection set.
101 assert(!oops_into_cset, "should be");
102
103 if (_concurrent && SuspendibleThreadSet::should_yield()) {
104 // Caller will actually yield.
105 return false;
106 }
107 // Otherwise, we finished successfully; return true.
108 return true;
109 }
110
111 void set_concurrent(bool b) { _concurrent = b; }
112 };
113
114
115 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
116 size_t _num_processed;
117 CardTableModRefBS* _ctbs;
118 int _histo[256];
119
120 public:
121 ClearLoggedCardTableEntryClosure() :
122 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
123 {
124 for (int i = 0; i < 256; i++) _histo[i] = 0;
125 }
126
127 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
128 unsigned char* ujb = (unsigned char*)card_ptr;
129 int ind = (int)(*ujb);
130 _histo[ind]++;
131
132 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
133 _num_processed++;
134
135 return true;
136 }
137
138 size_t num_processed() { return _num_processed; }
139
140 void print_histo() {
141 gclog_or_tty->print_cr("Card table value histogram:");
142 for (int i = 0; i < 256; i++) {
143 if (_histo[i] != 0) {
144 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
145 }
146 }
147 }
148 };
149
150 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
151 private:
152 size_t _num_processed;
153
154 public:
155 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
156
157 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
158 *card_ptr = CardTableModRefBS::dirty_card_val();
159 _num_processed++;
160 return true;
161 }
162
163 size_t num_processed() const { return _num_processed; }
164 };
165
166 YoungList::YoungList(G1CollectedHeap* g1h) :
167 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
168 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
169 guarantee(check_list_empty(false), "just making sure...");
170 }
171
172 void YoungList::push_region(HeapRegion *hr) {
173 assert(!hr->is_young(), "should not already be young");
174 assert(hr->get_next_young_region() == NULL, "cause it should!");
175
176 hr->set_next_young_region(_head);
177 _head = hr;
178
179 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
180 ++_length;
181 }
182
183 void YoungList::add_survivor_region(HeapRegion* hr) {
184 assert(hr->is_survivor(), "should be flagged as survivor region");
185 assert(hr->get_next_young_region() == NULL, "cause it should!");
186
187 hr->set_next_young_region(_survivor_head);
188 if (_survivor_head == NULL) {
189 _survivor_tail = hr;
190 }
191 _survivor_head = hr;
192 ++_survivor_length;
193 }
194
195 void YoungList::empty_list(HeapRegion* list) {
196 while (list != NULL) {
197 HeapRegion* next = list->get_next_young_region();
198 list->set_next_young_region(NULL);
199 list->uninstall_surv_rate_group();
200 // This is called before a Full GC and all the non-empty /
201 // non-humongous regions at the end of the Full GC will end up as
202 // old anyway.
203 list->set_old();
204 list = next;
205 }
206 }
207
208 void YoungList::empty_list() {
209 assert(check_list_well_formed(), "young list should be well formed");
210
211 empty_list(_head);
212 _head = NULL;
213 _length = 0;
214
215 empty_list(_survivor_head);
216 _survivor_head = NULL;
217 _survivor_tail = NULL;
218 _survivor_length = 0;
219
220 _last_sampled_rs_lengths = 0;
221
222 assert(check_list_empty(false), "just making sure...");
223 }
224
225 bool YoungList::check_list_well_formed() {
226 bool ret = true;
227
228 uint length = 0;
229 HeapRegion* curr = _head;
230 HeapRegion* last = NULL;
231 while (curr != NULL) {
232 if (!curr->is_young()) {
233 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
234 "incorrectly tagged (y: %d, surv: %d)",
235 curr->bottom(), curr->end(),
236 curr->is_young(), curr->is_survivor());
237 ret = false;
238 }
239 ++length;
240 last = curr;
241 curr = curr->get_next_young_region();
242 }
243 ret = ret && (length == _length);
244
245 if (!ret) {
246 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
247 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
248 length, _length);
249 }
250
251 return ret;
252 }
253
254 bool YoungList::check_list_empty(bool check_sample) {
255 bool ret = true;
256
257 if (_length != 0) {
258 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
259 _length);
260 ret = false;
261 }
262 if (check_sample && _last_sampled_rs_lengths != 0) {
263 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
264 ret = false;
265 }
266 if (_head != NULL) {
267 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
268 ret = false;
269 }
270 if (!ret) {
271 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
272 }
273
274 return ret;
275 }
276
277 void
278 YoungList::rs_length_sampling_init() {
279 _sampled_rs_lengths = 0;
280 _curr = _head;
281 }
282
283 bool
284 YoungList::rs_length_sampling_more() {
285 return _curr != NULL;
286 }
287
288 void
289 YoungList::rs_length_sampling_next() {
290 assert( _curr != NULL, "invariant" );
291 size_t rs_length = _curr->rem_set()->occupied();
292
293 _sampled_rs_lengths += rs_length;
294
295 // The current region may not yet have been added to the
296 // incremental collection set (it gets added when it is
297 // retired as the current allocation region).
298 if (_curr->in_collection_set()) {
299 // Update the collection set policy information for this region
300 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
301 }
302
303 _curr = _curr->get_next_young_region();
304 if (_curr == NULL) {
305 _last_sampled_rs_lengths = _sampled_rs_lengths;
306 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
307 }
308 }
309
310 void
311 YoungList::reset_auxilary_lists() {
312 guarantee( is_empty(), "young list should be empty" );
313 assert(check_list_well_formed(), "young list should be well formed");
314
315 // Add survivor regions to SurvRateGroup.
316 _g1h->g1_policy()->note_start_adding_survivor_regions();
317 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
318
319 int young_index_in_cset = 0;
320 for (HeapRegion* curr = _survivor_head;
321 curr != NULL;
322 curr = curr->get_next_young_region()) {
323 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
324
325 // The region is a non-empty survivor so let's add it to
326 // the incremental collection set for the next evacuation
327 // pause.
328 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
329 young_index_in_cset += 1;
330 }
331 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
332 _g1h->g1_policy()->note_stop_adding_survivor_regions();
333
334 _head = _survivor_head;
335 _length = _survivor_length;
336 if (_survivor_head != NULL) {
337 assert(_survivor_tail != NULL, "cause it shouldn't be");
338 assert(_survivor_length > 0, "invariant");
339 _survivor_tail->set_next_young_region(NULL);
340 }
341
342 // Don't clear the survivor list handles until the start of
343 // the next evacuation pause - we need it in order to re-tag
344 // the survivor regions from this evacuation pause as 'young'
345 // at the start of the next.
346
347 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
348
349 assert(check_list_well_formed(), "young list should be well formed");
350 }
351
352 void YoungList::print() {
353 HeapRegion* lists[] = {_head, _survivor_head};
354 const char* names[] = {"YOUNG", "SURVIVOR"};
355
356 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
357 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
358 HeapRegion *curr = lists[list];
359 if (curr == NULL)
360 gclog_or_tty->print_cr(" empty");
361 while (curr != NULL) {
362 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
363 HR_FORMAT_PARAMS(curr),
364 curr->prev_top_at_mark_start(),
365 curr->next_top_at_mark_start(),
366 curr->age_in_surv_rate_group_cond());
367 curr = curr->get_next_young_region();
368 }
369 }
370
371 gclog_or_tty->cr();
372 }
373
374 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
375 OtherRegionsTable::invalidate(start_idx, num_regions);
376 }
377
378 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
379 // The from card cache is not the memory that is actually committed. So we cannot
380 // take advantage of the zero_filled parameter.
381 reset_from_card_cache(start_idx, num_regions);
382 }
383
384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
385 {
386 // Claim the right to put the region on the dirty cards region list
387 // by installing a self pointer.
388 HeapRegion* next = hr->get_next_dirty_cards_region();
389 if (next == NULL) {
390 HeapRegion* res = (HeapRegion*)
391 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
392 NULL);
393 if (res == NULL) {
394 HeapRegion* head;
395 do {
396 // Put the region to the dirty cards region list.
397 head = _dirty_cards_region_list;
398 next = (HeapRegion*)
399 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
400 if (next == head) {
401 assert(hr->get_next_dirty_cards_region() == hr,
402 "hr->get_next_dirty_cards_region() != hr");
403 if (next == NULL) {
404 // The last region in the list points to itself.
405 hr->set_next_dirty_cards_region(hr);
406 } else {
407 hr->set_next_dirty_cards_region(next);
408 }
409 }
410 } while (next != head);
411 }
412 }
413 }
414
415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
416 {
417 HeapRegion* head;
418 HeapRegion* hr;
419 do {
420 head = _dirty_cards_region_list;
421 if (head == NULL) {
422 return NULL;
423 }
424 HeapRegion* new_head = head->get_next_dirty_cards_region();
425 if (head == new_head) {
426 // The last region.
427 new_head = NULL;
428 }
429 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
430 head);
431 } while (hr != head);
432 assert(hr != NULL, "invariant");
433 hr->set_next_dirty_cards_region(NULL);
434 return hr;
435 }
436
437 #ifdef ASSERT
438 // A region is added to the collection set as it is retired
439 // so an address p can point to a region which will be in the
440 // collection set but has not yet been retired. This method
441 // therefore is only accurate during a GC pause after all
442 // regions have been retired. It is used for debugging
443 // to check if an nmethod has references to objects that can
444 // be move during a partial collection. Though it can be
445 // inaccurate, it is sufficient for G1 because the conservative
446 // implementation of is_scavengable() for G1 will indicate that
447 // all nmethods must be scanned during a partial collection.
448 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
449 if (p == NULL) {
450 return false;
451 }
452 return heap_region_containing(p)->in_collection_set();
453 }
454 #endif
455
456 // Returns true if the reference points to an object that
457 // can move in an incremental collection.
458 bool G1CollectedHeap::is_scavengable(const void* p) {
459 HeapRegion* hr = heap_region_containing(p);
460 return !hr->isHumongous();
461 }
462
463 void G1CollectedHeap::check_ct_logs_at_safepoint() {
464 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
465 CardTableModRefBS* ct_bs = g1_barrier_set();
466
467 // Count the dirty cards at the start.
468 CountNonCleanMemRegionClosure count1(this);
469 ct_bs->mod_card_iterate(&count1);
470 int orig_count = count1.n();
471
472 // First clear the logged cards.
473 ClearLoggedCardTableEntryClosure clear;
474 dcqs.apply_closure_to_all_completed_buffers(&clear);
475 dcqs.iterate_closure_all_threads(&clear, false);
476 clear.print_histo();
477
478 // Now ensure that there's no dirty cards.
479 CountNonCleanMemRegionClosure count2(this);
480 ct_bs->mod_card_iterate(&count2);
481 if (count2.n() != 0) {
482 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
483 count2.n(), orig_count);
484 }
485 guarantee(count2.n() == 0, "Card table should be clean.");
486
487 RedirtyLoggedCardTableEntryClosure redirty;
488 dcqs.apply_closure_to_all_completed_buffers(&redirty);
489 dcqs.iterate_closure_all_threads(&redirty, false);
490 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
491 clear.num_processed(), orig_count);
492 guarantee(redirty.num_processed() == clear.num_processed(),
493 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
494 redirty.num_processed(), clear.num_processed()));
495
496 CountNonCleanMemRegionClosure count3(this);
497 ct_bs->mod_card_iterate(&count3);
498 if (count3.n() != orig_count) {
499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
500 orig_count, count3.n());
501 guarantee(count3.n() >= orig_count, "Should have restored them all.");
502 }
503 }
504
505 // Private class members.
506
507 G1CollectedHeap* G1CollectedHeap::_g1h;
508
509 // Private methods.
510
511 HeapRegion*
512 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
513 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
514 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
515 if (!_secondary_free_list.is_empty()) {
516 if (G1ConcRegionFreeingVerbose) {
517 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
518 "secondary_free_list has %u entries",
519 _secondary_free_list.length());
520 }
521 // It looks as if there are free regions available on the
522 // secondary_free_list. Let's move them to the free_list and try
523 // again to allocate from it.
524 append_secondary_free_list();
525
526 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
527 "empty we should have moved at least one entry to the free_list");
528 HeapRegion* res = _hrm.allocate_free_region(is_old);
529 if (G1ConcRegionFreeingVerbose) {
530 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
531 "allocated "HR_FORMAT" from secondary_free_list",
532 HR_FORMAT_PARAMS(res));
533 }
534 return res;
535 }
536
537 // Wait here until we get notified either when (a) there are no
538 // more free regions coming or (b) some regions have been moved on
539 // the secondary_free_list.
540 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
541 }
542
543 if (G1ConcRegionFreeingVerbose) {
544 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
545 "could not allocate from secondary_free_list");
546 }
547 return NULL;
548 }
549
550 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
551 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
552 "the only time we use this to allocate a humongous region is "
553 "when we are allocating a single humongous region");
554
555 HeapRegion* res;
556 if (G1StressConcRegionFreeing) {
557 if (!_secondary_free_list.is_empty()) {
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "forced to look at the secondary_free_list");
561 }
562 res = new_region_try_secondary_free_list(is_old);
563 if (res != NULL) {
564 return res;
565 }
566 }
567 }
568
569 res = _hrm.allocate_free_region(is_old);
570
571 if (res == NULL) {
572 if (G1ConcRegionFreeingVerbose) {
573 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
574 "res == NULL, trying the secondary_free_list");
575 }
576 res = new_region_try_secondary_free_list(is_old);
577 }
578 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
579 // Currently, only attempts to allocate GC alloc regions set
580 // do_expand to true. So, we should only reach here during a
581 // safepoint. If this assumption changes we might have to
582 // reconsider the use of _expand_heap_after_alloc_failure.
583 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
584
585 ergo_verbose1(ErgoHeapSizing,
586 "attempt heap expansion",
587 ergo_format_reason("region allocation request failed")
588 ergo_format_byte("allocation request"),
589 word_size * HeapWordSize);
590 if (expand(word_size * HeapWordSize)) {
591 // Given that expand() succeeded in expanding the heap, and we
592 // always expand the heap by an amount aligned to the heap
593 // region size, the free list should in theory not be empty.
594 // In either case allocate_free_region() will check for NULL.
595 res = _hrm.allocate_free_region(is_old);
596 } else {
597 _expand_heap_after_alloc_failure = false;
598 }
599 }
600 return res;
601 }
602
603 HeapWord*
604 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
605 uint num_regions,
606 size_t word_size,
607 AllocationContext_t context) {
608 assert(first != G1_NO_HRM_INDEX, "pre-condition");
609 assert(isHumongous(word_size), "word_size should be humongous");
610 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
611
612 // Index of last region in the series + 1.
613 uint last = first + num_regions;
614
615 // We need to initialize the region(s) we just discovered. This is
616 // a bit tricky given that it can happen concurrently with
617 // refinement threads refining cards on these regions and
618 // potentially wanting to refine the BOT as they are scanning
619 // those cards (this can happen shortly after a cleanup; see CR
620 // 6991377). So we have to set up the region(s) carefully and in
621 // a specific order.
622
623 // The word size sum of all the regions we will allocate.
624 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
625 assert(word_size <= word_size_sum, "sanity");
626
627 // This will be the "starts humongous" region.
628 HeapRegion* first_hr = region_at(first);
629 // The header of the new object will be placed at the bottom of
630 // the first region.
631 HeapWord* new_obj = first_hr->bottom();
632 // This will be the new end of the first region in the series that
633 // should also match the end of the last region in the series.
634 HeapWord* new_end = new_obj + word_size_sum;
635 // This will be the new top of the first region that will reflect
636 // this allocation.
637 HeapWord* new_top = new_obj + word_size;
638
639 // First, we need to zero the header of the space that we will be
640 // allocating. When we update top further down, some refinement
641 // threads might try to scan the region. By zeroing the header we
642 // ensure that any thread that will try to scan the region will
643 // come across the zero klass word and bail out.
644 //
645 // NOTE: It would not have been correct to have used
646 // CollectedHeap::fill_with_object() and make the space look like
647 // an int array. The thread that is doing the allocation will
648 // later update the object header to a potentially different array
649 // type and, for a very short period of time, the klass and length
650 // fields will be inconsistent. This could cause a refinement
651 // thread to calculate the object size incorrectly.
652 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
653
654 // We will set up the first region as "starts humongous". This
655 // will also update the BOT covering all the regions to reflect
656 // that there is a single object that starts at the bottom of the
657 // first region.
658 first_hr->set_startsHumongous(new_top, new_end);
659 first_hr->set_allocation_context(context);
660 // Then, if there are any, we will set up the "continues
661 // humongous" regions.
662 HeapRegion* hr = NULL;
663 for (uint i = first + 1; i < last; ++i) {
664 hr = region_at(i);
665 hr->set_continuesHumongous(first_hr);
666 hr->set_allocation_context(context);
667 }
668 // If we have "continues humongous" regions (hr != NULL), then the
669 // end of the last one should match new_end.
670 assert(hr == NULL || hr->end() == new_end, "sanity");
671
672 // Up to this point no concurrent thread would have been able to
673 // do any scanning on any region in this series. All the top
674 // fields still point to bottom, so the intersection between
675 // [bottom,top] and [card_start,card_end] will be empty. Before we
676 // update the top fields, we'll do a storestore to make sure that
677 // no thread sees the update to top before the zeroing of the
678 // object header and the BOT initialization.
679 OrderAccess::storestore();
680
681 // Now that the BOT and the object header have been initialized,
682 // we can update top of the "starts humongous" region.
683 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
684 "new_top should be in this region");
685 first_hr->set_top(new_top);
686 if (_hr_printer.is_active()) {
687 HeapWord* bottom = first_hr->bottom();
688 HeapWord* end = first_hr->orig_end();
689 if ((first + 1) == last) {
690 // the series has a single humongous region
691 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
692 } else {
693 // the series has more than one humongous regions
694 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
695 }
696 }
697
698 // Now, we will update the top fields of the "continues humongous"
699 // regions. The reason we need to do this is that, otherwise,
700 // these regions would look empty and this will confuse parts of
701 // G1. For example, the code that looks for a consecutive number
702 // of empty regions will consider them empty and try to
703 // re-allocate them. We can extend is_empty() to also include
704 // !continuesHumongous(), but it is easier to just update the top
705 // fields here. The way we set top for all regions (i.e., top ==
706 // end for all regions but the last one, top == new_top for the
707 // last one) is actually used when we will free up the humongous
708 // region in free_humongous_region().
709 hr = NULL;
710 for (uint i = first + 1; i < last; ++i) {
711 hr = region_at(i);
712 if ((i + 1) == last) {
713 // last continues humongous region
714 assert(hr->bottom() < new_top && new_top <= hr->end(),
715 "new_top should fall on this region");
716 hr->set_top(new_top);
717 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
718 } else {
719 // not last one
720 assert(new_top > hr->end(), "new_top should be above this region");
721 hr->set_top(hr->end());
722 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
723 }
724 }
725 // If we have continues humongous regions (hr != NULL), then the
726 // end of the last one should match new_end and its top should
727 // match new_top.
728 assert(hr == NULL ||
729 (hr->end() == new_end && hr->top() == new_top), "sanity");
730 check_bitmaps("Humongous Region Allocation", first_hr);
731
732 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
733 _allocator->increase_used(first_hr->used());
734 _humongous_set.add(first_hr);
735
736 return new_obj;
737 }
738
739 // If could fit into free regions w/o expansion, try.
740 // Otherwise, if can expand, do so.
741 // Otherwise, if using ex regions might help, try with ex given back.
742 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
743 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
744
745 verify_region_sets_optional();
746
747 uint first = G1_NO_HRM_INDEX;
748 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
749
750 if (obj_regions == 1) {
751 // Only one region to allocate, try to use a fast path by directly allocating
752 // from the free lists. Do not try to expand here, we will potentially do that
753 // later.
754 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
755 if (hr != NULL) {
756 first = hr->hrm_index();
757 }
758 } else {
759 // We can't allocate humongous regions spanning more than one region while
760 // cleanupComplete() is running, since some of the regions we find to be
761 // empty might not yet be added to the free list. It is not straightforward
762 // to know in which list they are on so that we can remove them. We only
763 // need to do this if we need to allocate more than one region to satisfy the
764 // current humongous allocation request. If we are only allocating one region
765 // we use the one-region region allocation code (see above), that already
766 // potentially waits for regions from the secondary free list.
767 wait_while_free_regions_coming();
768 append_secondary_free_list_if_not_empty_with_lock();
769
770 // Policy: Try only empty regions (i.e. already committed first). Maybe we
771 // are lucky enough to find some.
772 first = _hrm.find_contiguous_only_empty(obj_regions);
773 if (first != G1_NO_HRM_INDEX) {
774 _hrm.allocate_free_regions_starting_at(first, obj_regions);
775 }
776 }
777
778 if (first == G1_NO_HRM_INDEX) {
779 // Policy: We could not find enough regions for the humongous object in the
780 // free list. Look through the heap to find a mix of free and uncommitted regions.
781 // If so, try expansion.
782 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
783 if (first != G1_NO_HRM_INDEX) {
784 // We found something. Make sure these regions are committed, i.e. expand
785 // the heap. Alternatively we could do a defragmentation GC.
786 ergo_verbose1(ErgoHeapSizing,
787 "attempt heap expansion",
788 ergo_format_reason("humongous allocation request failed")
789 ergo_format_byte("allocation request"),
790 word_size * HeapWordSize);
791
792 _hrm.expand_at(first, obj_regions);
793 g1_policy()->record_new_heap_size(num_regions());
794
795 #ifdef ASSERT
796 for (uint i = first; i < first + obj_regions; ++i) {
797 HeapRegion* hr = region_at(i);
798 assert(hr->is_free(), "sanity");
799 assert(hr->is_empty(), "sanity");
800 assert(is_on_master_free_list(hr), "sanity");
801 }
802 #endif
803 _hrm.allocate_free_regions_starting_at(first, obj_regions);
804 } else {
805 // Policy: Potentially trigger a defragmentation GC.
806 }
807 }
808
809 HeapWord* result = NULL;
810 if (first != G1_NO_HRM_INDEX) {
811 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
812 word_size, context);
813 assert(result != NULL, "it should always return a valid result");
814
815 // A successful humongous object allocation changes the used space
816 // information of the old generation so we need to recalculate the
817 // sizes and update the jstat counters here.
818 g1mm()->update_sizes();
819 }
820
821 verify_region_sets_optional();
822
823 return result;
824 }
825
826 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
827 assert_heap_not_locked_and_not_at_safepoint();
828 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
829
830 uint dummy_gc_count_before;
831 uint dummy_gclocker_retry_count = 0;
832 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
833 }
834
835 HeapWord*
836 G1CollectedHeap::mem_allocate(size_t word_size,
837 bool* gc_overhead_limit_was_exceeded) {
838 assert_heap_not_locked_and_not_at_safepoint();
839
840 // Loop until the allocation is satisfied, or unsatisfied after GC.
841 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
842 uint gc_count_before;
843
844 HeapWord* result = NULL;
845 if (!isHumongous(word_size)) {
846 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
847 } else {
848 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
849 }
850 if (result != NULL) {
851 return result;
852 }
853
854 // Create the garbage collection operation...
855 VM_G1CollectForAllocation op(gc_count_before, word_size);
856 op.set_allocation_context(AllocationContext::current());
857
858 // ...and get the VM thread to execute it.
859 VMThread::execute(&op);
860
861 if (op.prologue_succeeded() && op.pause_succeeded()) {
862 // If the operation was successful we'll return the result even
863 // if it is NULL. If the allocation attempt failed immediately
864 // after a Full GC, it's unlikely we'll be able to allocate now.
865 HeapWord* result = op.result();
866 if (result != NULL && !isHumongous(word_size)) {
867 // Allocations that take place on VM operations do not do any
868 // card dirtying and we have to do it here. We only have to do
869 // this for non-humongous allocations, though.
870 dirty_young_block(result, word_size);
871 }
872 return result;
873 } else {
874 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
875 return NULL;
876 }
877 assert(op.result() == NULL,
878 "the result should be NULL if the VM op did not succeed");
879 }
880
881 // Give a warning if we seem to be looping forever.
882 if ((QueuedAllocationWarningCount > 0) &&
883 (try_count % QueuedAllocationWarningCount == 0)) {
884 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
885 }
886 }
887
888 ShouldNotReachHere();
889 return NULL;
890 }
891
892 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
893 AllocationContext_t context,
894 uint* gc_count_before_ret,
895 uint* gclocker_retry_count_ret) {
896 // Make sure you read the note in attempt_allocation_humongous().
897
898 assert_heap_not_locked_and_not_at_safepoint();
899 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
900 "be called for humongous allocation requests");
901
902 // We should only get here after the first-level allocation attempt
903 // (attempt_allocation()) failed to allocate.
904
905 // We will loop until a) we manage to successfully perform the
906 // allocation or b) we successfully schedule a collection which
907 // fails to perform the allocation. b) is the only case when we'll
908 // return NULL.
909 HeapWord* result = NULL;
910 for (int try_count = 1; /* we'll return */; try_count += 1) {
911 bool should_try_gc;
912 uint gc_count_before;
913
914 {
915 MutexLockerEx x(Heap_lock);
916 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
917 false /* bot_updates */);
918 if (result != NULL) {
919 return result;
920 }
921
922 // If we reach here, attempt_allocation_locked() above failed to
923 // allocate a new region. So the mutator alloc region should be NULL.
924 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
925
926 if (GC_locker::is_active_and_needs_gc()) {
927 if (g1_policy()->can_expand_young_list()) {
928 // No need for an ergo verbose message here,
929 // can_expand_young_list() does this when it returns true.
930 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
931 false /* bot_updates */);
932 if (result != NULL) {
933 return result;
934 }
935 }
936 should_try_gc = false;
937 } else {
938 // The GCLocker may not be active but the GCLocker initiated
939 // GC may not yet have been performed (GCLocker::needs_gc()
940 // returns true). In this case we do not try this GC and
941 // wait until the GCLocker initiated GC is performed, and
942 // then retry the allocation.
943 if (GC_locker::needs_gc()) {
944 should_try_gc = false;
945 } else {
946 // Read the GC count while still holding the Heap_lock.
947 gc_count_before = total_collections();
948 should_try_gc = true;
949 }
950 }
951 }
952
953 if (should_try_gc) {
954 bool succeeded;
955 result = do_collection_pause(word_size, gc_count_before, &succeeded,
956 GCCause::_g1_inc_collection_pause);
957 if (result != NULL) {
958 assert(succeeded, "only way to get back a non-NULL result");
959 return result;
960 }
961
962 if (succeeded) {
963 // If we get here we successfully scheduled a collection which
964 // failed to allocate. No point in trying to allocate
965 // further. We'll just return NULL.
966 MutexLockerEx x(Heap_lock);
967 *gc_count_before_ret = total_collections();
968 return NULL;
969 }
970 } else {
971 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
972 MutexLockerEx x(Heap_lock);
973 *gc_count_before_ret = total_collections();
974 return NULL;
975 }
976 // The GCLocker is either active or the GCLocker initiated
977 // GC has not yet been performed. Stall until it is and
978 // then retry the allocation.
979 GC_locker::stall_until_clear();
980 (*gclocker_retry_count_ret) += 1;
981 }
982
983 // We can reach here if we were unsuccessful in scheduling a
984 // collection (because another thread beat us to it) or if we were
985 // stalled due to the GC locker. In either can we should retry the
986 // allocation attempt in case another thread successfully
987 // performed a collection and reclaimed enough space. We do the
988 // first attempt (without holding the Heap_lock) here and the
989 // follow-on attempt will be at the start of the next loop
990 // iteration (after taking the Heap_lock).
991 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
992 false /* bot_updates */);
993 if (result != NULL) {
994 return result;
995 }
996
997 // Give a warning if we seem to be looping forever.
998 if ((QueuedAllocationWarningCount > 0) &&
999 (try_count % QueuedAllocationWarningCount == 0)) {
1000 warning("G1CollectedHeap::attempt_allocation_slow() "
1001 "retries %d times", try_count);
1002 }
1003 }
1004
1005 ShouldNotReachHere();
1006 return NULL;
1007 }
1008
1009 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1010 uint* gc_count_before_ret,
1011 uint* gclocker_retry_count_ret) {
1012 // The structure of this method has a lot of similarities to
1013 // attempt_allocation_slow(). The reason these two were not merged
1014 // into a single one is that such a method would require several "if
1015 // allocation is not humongous do this, otherwise do that"
1016 // conditional paths which would obscure its flow. In fact, an early
1017 // version of this code did use a unified method which was harder to
1018 // follow and, as a result, it had subtle bugs that were hard to
1019 // track down. So keeping these two methods separate allows each to
1020 // be more readable. It will be good to keep these two in sync as
1021 // much as possible.
1022
1023 assert_heap_not_locked_and_not_at_safepoint();
1024 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1025 "should only be called for humongous allocations");
1026
1027 // Humongous objects can exhaust the heap quickly, so we should check if we
1028 // need to start a marking cycle at each humongous object allocation. We do
1029 // the check before we do the actual allocation. The reason for doing it
1030 // before the allocation is that we avoid having to keep track of the newly
1031 // allocated memory while we do a GC.
1032 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1033 word_size)) {
1034 collect(GCCause::_g1_humongous_allocation);
1035 }
1036
1037 // We will loop until a) we manage to successfully perform the
1038 // allocation or b) we successfully schedule a collection which
1039 // fails to perform the allocation. b) is the only case when we'll
1040 // return NULL.
1041 HeapWord* result = NULL;
1042 for (int try_count = 1; /* we'll return */; try_count += 1) {
1043 bool should_try_gc;
1044 uint gc_count_before;
1045
1046 {
1047 MutexLockerEx x(Heap_lock);
1048
1049 // Given that humongous objects are not allocated in young
1050 // regions, we'll first try to do the allocation without doing a
1051 // collection hoping that there's enough space in the heap.
1052 result = humongous_obj_allocate(word_size, AllocationContext::current());
1053 if (result != NULL) {
1054 return result;
1055 }
1056
1057 if (GC_locker::is_active_and_needs_gc()) {
1058 should_try_gc = false;
1059 } else {
1060 // The GCLocker may not be active but the GCLocker initiated
1061 // GC may not yet have been performed (GCLocker::needs_gc()
1062 // returns true). In this case we do not try this GC and
1063 // wait until the GCLocker initiated GC is performed, and
1064 // then retry the allocation.
1065 if (GC_locker::needs_gc()) {
1066 should_try_gc = false;
1067 } else {
1068 // Read the GC count while still holding the Heap_lock.
1069 gc_count_before = total_collections();
1070 should_try_gc = true;
1071 }
1072 }
1073 }
1074
1075 if (should_try_gc) {
1076 // If we failed to allocate the humongous object, we should try to
1077 // do a collection pause (if we're allowed) in case it reclaims
1078 // enough space for the allocation to succeed after the pause.
1079
1080 bool succeeded;
1081 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1082 GCCause::_g1_humongous_allocation);
1083 if (result != NULL) {
1084 assert(succeeded, "only way to get back a non-NULL result");
1085 return result;
1086 }
1087
1088 if (succeeded) {
1089 // If we get here we successfully scheduled a collection which
1090 // failed to allocate. No point in trying to allocate
1091 // further. We'll just return NULL.
1092 MutexLockerEx x(Heap_lock);
1093 *gc_count_before_ret = total_collections();
1094 return NULL;
1095 }
1096 } else {
1097 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1098 MutexLockerEx x(Heap_lock);
1099 *gc_count_before_ret = total_collections();
1100 return NULL;
1101 }
1102 // The GCLocker is either active or the GCLocker initiated
1103 // GC has not yet been performed. Stall until it is and
1104 // then retry the allocation.
1105 GC_locker::stall_until_clear();
1106 (*gclocker_retry_count_ret) += 1;
1107 }
1108
1109 // We can reach here if we were unsuccessful in scheduling a
1110 // collection (because another thread beat us to it) or if we were
1111 // stalled due to the GC locker. In either can we should retry the
1112 // allocation attempt in case another thread successfully
1113 // performed a collection and reclaimed enough space. Give a
1114 // warning if we seem to be looping forever.
1115
1116 if ((QueuedAllocationWarningCount > 0) &&
1117 (try_count % QueuedAllocationWarningCount == 0)) {
1118 warning("G1CollectedHeap::attempt_allocation_humongous() "
1119 "retries %d times", try_count);
1120 }
1121 }
1122
1123 ShouldNotReachHere();
1124 return NULL;
1125 }
1126
1127 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1128 AllocationContext_t context,
1129 bool expect_null_mutator_alloc_region) {
1130 assert_at_safepoint(true /* should_be_vm_thread */);
1131 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1132 !expect_null_mutator_alloc_region,
1133 "the current alloc region was unexpectedly found to be non-NULL");
1134
1135 if (!isHumongous(word_size)) {
1136 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1137 false /* bot_updates */);
1138 } else {
1139 HeapWord* result = humongous_obj_allocate(word_size, context);
1140 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1141 g1_policy()->set_initiate_conc_mark_if_possible();
1142 }
1143 return result;
1144 }
1145
1146 ShouldNotReachHere();
1147 }
1148
1149 class PostMCRemSetClearClosure: public HeapRegionClosure {
1150 G1CollectedHeap* _g1h;
1151 ModRefBarrierSet* _mr_bs;
1152 public:
1153 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1154 _g1h(g1h), _mr_bs(mr_bs) {}
1155
1156 bool doHeapRegion(HeapRegion* r) {
1157 HeapRegionRemSet* hrrs = r->rem_set();
1158
1159 if (r->continuesHumongous()) {
1160 // We'll assert that the strong code root list and RSet is empty
1161 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1162 assert(hrrs->occupied() == 0, "RSet should be empty");
1163 return false;
1164 }
1165
1166 _g1h->reset_gc_time_stamps(r);
1167 hrrs->clear();
1168 // You might think here that we could clear just the cards
1169 // corresponding to the used region. But no: if we leave a dirty card
1170 // in a region we might allocate into, then it would prevent that card
1171 // from being enqueued, and cause it to be missed.
1172 // Re: the performance cost: we shouldn't be doing full GC anyway!
1173 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1174
1175 return false;
1176 }
1177 };
1178
1179 void G1CollectedHeap::clear_rsets_post_compaction() {
1180 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1181 heap_region_iterate(&rs_clear);
1182 }
1183
1184 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1185 G1CollectedHeap* _g1h;
1186 UpdateRSOopClosure _cl;
1187 int _worker_i;
1188 public:
1189 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1190 _cl(g1->g1_rem_set(), worker_i),
1191 _worker_i(worker_i),
1192 _g1h(g1)
1193 { }
1194
1195 bool doHeapRegion(HeapRegion* r) {
1196 if (!r->continuesHumongous()) {
1197 _cl.set_from(r);
1198 r->oop_iterate(&_cl);
1199 }
1200 return false;
1201 }
1202 };
1203
1204 class ParRebuildRSTask: public AbstractGangTask {
1205 G1CollectedHeap* _g1;
1206 public:
1207 ParRebuildRSTask(G1CollectedHeap* g1)
1208 : AbstractGangTask("ParRebuildRSTask"),
1209 _g1(g1)
1210 { }
1211
1212 void work(uint worker_id) {
1213 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1214 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1215 _g1->workers()->active_workers(),
1216 HeapRegion::RebuildRSClaimValue);
1217 }
1218 };
1219
1220 class PostCompactionPrinterClosure: public HeapRegionClosure {
1221 private:
1222 G1HRPrinter* _hr_printer;
1223 public:
1224 bool doHeapRegion(HeapRegion* hr) {
1225 assert(!hr->is_young(), "not expecting to find young regions");
1226 if (hr->is_free()) {
1227 // We only generate output for non-empty regions.
1228 } else if (hr->startsHumongous()) {
1229 if (hr->region_num() == 1) {
1230 // single humongous region
1231 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1232 } else {
1233 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1234 }
1235 } else if (hr->continuesHumongous()) {
1236 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1237 } else if (hr->is_old()) {
1238 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1239 } else {
1240 ShouldNotReachHere();
1241 }
1242 return false;
1243 }
1244
1245 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1246 : _hr_printer(hr_printer) { }
1247 };
1248
1249 void G1CollectedHeap::print_hrm_post_compaction() {
1250 PostCompactionPrinterClosure cl(hr_printer());
1251 heap_region_iterate(&cl);
1252 }
1253
1254 bool G1CollectedHeap::do_collection(bool explicit_gc,
1255 bool clear_all_soft_refs,
1256 size_t word_size) {
1257 assert_at_safepoint(true /* should_be_vm_thread */);
1258
1259 if (GC_locker::check_active_before_gc()) {
1260 return false;
1261 }
1262
1263 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1264 gc_timer->register_gc_start();
1265
1266 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1267 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1268
1269 SvcGCMarker sgcm(SvcGCMarker::FULL);
1270 ResourceMark rm;
1271
1272 print_heap_before_gc();
1273 trace_heap_before_gc(gc_tracer);
1274
1275 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1276
1277 verify_region_sets_optional();
1278
1279 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1280 collector_policy()->should_clear_all_soft_refs();
1281
1282 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1283
1284 {
1285 IsGCActiveMark x;
1286
1287 // Timing
1288 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1289 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1290
1291 {
1292 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1293 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1294 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1295
1296 double start = os::elapsedTime();
1297 g1_policy()->record_full_collection_start();
1298
1299 // Note: When we have a more flexible GC logging framework that
1300 // allows us to add optional attributes to a GC log record we
1301 // could consider timing and reporting how long we wait in the
1302 // following two methods.
1303 wait_while_free_regions_coming();
1304 // If we start the compaction before the CM threads finish
1305 // scanning the root regions we might trip them over as we'll
1306 // be moving objects / updating references. So let's wait until
1307 // they are done. By telling them to abort, they should complete
1308 // early.
1309 _cm->root_regions()->abort();
1310 _cm->root_regions()->wait_until_scan_finished();
1311 append_secondary_free_list_if_not_empty_with_lock();
1312
1313 gc_prologue(true);
1314 increment_total_collections(true /* full gc */);
1315 increment_old_marking_cycles_started();
1316
1317 assert(used() == recalculate_used(), "Should be equal");
1318
1319 verify_before_gc();
1320
1321 check_bitmaps("Full GC Start");
1322 pre_full_gc_dump(gc_timer);
1323
1324 COMPILER2_PRESENT(DerivedPointerTable::clear());
1325
1326 // Disable discovery and empty the discovered lists
1327 // for the CM ref processor.
1328 ref_processor_cm()->disable_discovery();
1329 ref_processor_cm()->abandon_partial_discovery();
1330 ref_processor_cm()->verify_no_references_recorded();
1331
1332 // Abandon current iterations of concurrent marking and concurrent
1333 // refinement, if any are in progress. We have to do this before
1334 // wait_until_scan_finished() below.
1335 concurrent_mark()->abort();
1336
1337 // Make sure we'll choose a new allocation region afterwards.
1338 _allocator->release_mutator_alloc_region();
1339 _allocator->abandon_gc_alloc_regions();
1340 g1_rem_set()->cleanupHRRS();
1341
1342 // We should call this after we retire any currently active alloc
1343 // regions so that all the ALLOC / RETIRE events are generated
1344 // before the start GC event.
1345 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1346
1347 // We may have added regions to the current incremental collection
1348 // set between the last GC or pause and now. We need to clear the
1349 // incremental collection set and then start rebuilding it afresh
1350 // after this full GC.
1351 abandon_collection_set(g1_policy()->inc_cset_head());
1352 g1_policy()->clear_incremental_cset();
1353 g1_policy()->stop_incremental_cset_building();
1354
1355 tear_down_region_sets(false /* free_list_only */);
1356 g1_policy()->set_gcs_are_young(true);
1357
1358 // See the comments in g1CollectedHeap.hpp and
1359 // G1CollectedHeap::ref_processing_init() about
1360 // how reference processing currently works in G1.
1361
1362 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1363 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1364
1365 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1366 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1367
1368 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1369 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1370
1371 // Do collection work
1372 {
1373 HandleMark hm; // Discard invalid handles created during gc
1374 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1375 }
1376
1377 assert(num_free_regions() == 0, "we should not have added any free regions");
1378 rebuild_region_sets(false /* free_list_only */);
1379
1380 // Enqueue any discovered reference objects that have
1381 // not been removed from the discovered lists.
1382 ref_processor_stw()->enqueue_discovered_references();
1383
1384 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1385
1386 MemoryService::track_memory_usage();
1387
1388 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1389 ref_processor_stw()->verify_no_references_recorded();
1390
1391 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1392 ClassLoaderDataGraph::purge();
1393 MetaspaceAux::verify_metrics();
1394
1395 // Note: since we've just done a full GC, concurrent
1396 // marking is no longer active. Therefore we need not
1397 // re-enable reference discovery for the CM ref processor.
1398 // That will be done at the start of the next marking cycle.
1399 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1400 ref_processor_cm()->verify_no_references_recorded();
1401
1402 reset_gc_time_stamp();
1403 // Since everything potentially moved, we will clear all remembered
1404 // sets, and clear all cards. Later we will rebuild remembered
1405 // sets. We will also reset the GC time stamps of the regions.
1406 clear_rsets_post_compaction();
1407 check_gc_time_stamps();
1408
1409 // Resize the heap if necessary.
1410 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1411
1412 if (_hr_printer.is_active()) {
1413 // We should do this after we potentially resize the heap so
1414 // that all the COMMIT / UNCOMMIT events are generated before
1415 // the end GC event.
1416
1417 print_hrm_post_compaction();
1418 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1419 }
1420
1421 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1422 if (hot_card_cache->use_cache()) {
1423 hot_card_cache->reset_card_counts();
1424 hot_card_cache->reset_hot_cache();
1425 }
1426
1427 // Rebuild remembered sets of all regions.
1428 if (G1CollectedHeap::use_parallel_gc_threads()) {
1429 uint n_workers =
1430 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1431 workers()->active_workers(),
1432 Threads::number_of_non_daemon_threads());
1433 assert(UseDynamicNumberOfGCThreads ||
1434 n_workers == workers()->total_workers(),
1435 "If not dynamic should be using all the workers");
1436 workers()->set_active_workers(n_workers);
1437 // Set parallel threads in the heap (_n_par_threads) only
1438 // before a parallel phase and always reset it to 0 after
1439 // the phase so that the number of parallel threads does
1440 // no get carried forward to a serial phase where there
1441 // may be code that is "possibly_parallel".
1442 set_par_threads(n_workers);
1443
1444 ParRebuildRSTask rebuild_rs_task(this);
1445 assert(check_heap_region_claim_values(
1446 HeapRegion::InitialClaimValue), "sanity check");
1447 assert(UseDynamicNumberOfGCThreads ||
1448 workers()->active_workers() == workers()->total_workers(),
1449 "Unless dynamic should use total workers");
1450 // Use the most recent number of active workers
1451 assert(workers()->active_workers() > 0,
1452 "Active workers not properly set");
1453 set_par_threads(workers()->active_workers());
1454 workers()->run_task(&rebuild_rs_task);
1455 set_par_threads(0);
1456 assert(check_heap_region_claim_values(
1457 HeapRegion::RebuildRSClaimValue), "sanity check");
1458 reset_heap_region_claim_values();
1459 } else {
1460 RebuildRSOutOfRegionClosure rebuild_rs(this);
1461 heap_region_iterate(&rebuild_rs);
1462 }
1463
1464 // Rebuild the strong code root lists for each region
1465 rebuild_strong_code_roots();
1466
1467 if (true) { // FIXME
1468 MetaspaceGC::compute_new_size();
1469 }
1470
1471 #ifdef TRACESPINNING
1472 ParallelTaskTerminator::print_termination_counts();
1473 #endif
1474
1475 // Discard all rset updates
1476 JavaThread::dirty_card_queue_set().abandon_logs();
1477 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1478
1479 _young_list->reset_sampled_info();
1480 // At this point there should be no regions in the
1481 // entire heap tagged as young.
1482 assert(check_young_list_empty(true /* check_heap */),
1483 "young list should be empty at this point");
1484
1485 // Update the number of full collections that have been completed.
1486 increment_old_marking_cycles_completed(false /* concurrent */);
1487
1488 _hrm.verify_optional();
1489 verify_region_sets_optional();
1490
1491 verify_after_gc();
1492
1493 // Clear the previous marking bitmap, if needed for bitmap verification.
1494 // Note we cannot do this when we clear the next marking bitmap in
1495 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1496 // objects marked during a full GC against the previous bitmap.
1497 // But we need to clear it before calling check_bitmaps below since
1498 // the full GC has compacted objects and updated TAMS but not updated
1499 // the prev bitmap.
1500 if (G1VerifyBitmaps) {
1501 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1502 }
1503 check_bitmaps("Full GC End");
1504
1505 // Start a new incremental collection set for the next pause
1506 assert(g1_policy()->collection_set() == NULL, "must be");
1507 g1_policy()->start_incremental_cset_building();
1508
1509 clear_cset_fast_test();
1510
1511 _allocator->init_mutator_alloc_region();
1512
1513 double end = os::elapsedTime();
1514 g1_policy()->record_full_collection_end();
1515
1516 if (G1Log::fine()) {
1517 g1_policy()->print_heap_transition();
1518 }
1519
1520 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1521 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1522 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1523 // before any GC notifications are raised.
1524 g1mm()->update_sizes();
1525
1526 gc_epilogue(true);
1527 }
1528
1529 if (G1Log::finer()) {
1530 g1_policy()->print_detailed_heap_transition(true /* full */);
1531 }
1532
1533 print_heap_after_gc();
1534 trace_heap_after_gc(gc_tracer);
1535
1536 post_full_gc_dump(gc_timer);
1537
1538 gc_timer->register_gc_end();
1539 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1540 }
1541
1542 return true;
1543 }
1544
1545 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1546 // do_collection() will return whether it succeeded in performing
1547 // the GC. Currently, there is no facility on the
1548 // do_full_collection() API to notify the caller than the collection
1549 // did not succeed (e.g., because it was locked out by the GC
1550 // locker). So, right now, we'll ignore the return value.
1551 bool dummy = do_collection(true, /* explicit_gc */
1552 clear_all_soft_refs,
1553 0 /* word_size */);
1554 }
1555
1556 // This code is mostly copied from TenuredGeneration.
1557 void
1558 G1CollectedHeap::
1559 resize_if_necessary_after_full_collection(size_t word_size) {
1560 // Include the current allocation, if any, and bytes that will be
1561 // pre-allocated to support collections, as "used".
1562 const size_t used_after_gc = used();
1563 const size_t capacity_after_gc = capacity();
1564 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1565
1566 // This is enforced in arguments.cpp.
1567 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1568 "otherwise the code below doesn't make sense");
1569
1570 // We don't have floating point command-line arguments
1571 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1572 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1573 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1574 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1575
1576 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1577 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1578
1579 // We have to be careful here as these two calculations can overflow
1580 // 32-bit size_t's.
1581 double used_after_gc_d = (double) used_after_gc;
1582 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1583 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1584
1585 // Let's make sure that they are both under the max heap size, which
1586 // by default will make them fit into a size_t.
1587 double desired_capacity_upper_bound = (double) max_heap_size;
1588 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1589 desired_capacity_upper_bound);
1590 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1591 desired_capacity_upper_bound);
1592
1593 // We can now safely turn them into size_t's.
1594 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1595 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1596
1597 // This assert only makes sense here, before we adjust them
1598 // with respect to the min and max heap size.
1599 assert(minimum_desired_capacity <= maximum_desired_capacity,
1600 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1601 "maximum_desired_capacity = "SIZE_FORMAT,
1602 minimum_desired_capacity, maximum_desired_capacity));
1603
1604 // Should not be greater than the heap max size. No need to adjust
1605 // it with respect to the heap min size as it's a lower bound (i.e.,
1606 // we'll try to make the capacity larger than it, not smaller).
1607 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1608 // Should not be less than the heap min size. No need to adjust it
1609 // with respect to the heap max size as it's an upper bound (i.e.,
1610 // we'll try to make the capacity smaller than it, not greater).
1611 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1612
1613 if (capacity_after_gc < minimum_desired_capacity) {
1614 // Don't expand unless it's significant
1615 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1616 ergo_verbose4(ErgoHeapSizing,
1617 "attempt heap expansion",
1618 ergo_format_reason("capacity lower than "
1619 "min desired capacity after Full GC")
1620 ergo_format_byte("capacity")
1621 ergo_format_byte("occupancy")
1622 ergo_format_byte_perc("min desired capacity"),
1623 capacity_after_gc, used_after_gc,
1624 minimum_desired_capacity, (double) MinHeapFreeRatio);
1625 expand(expand_bytes);
1626
1627 // No expansion, now see if we want to shrink
1628 } else if (capacity_after_gc > maximum_desired_capacity) {
1629 // Capacity too large, compute shrinking size
1630 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1631 ergo_verbose4(ErgoHeapSizing,
1632 "attempt heap shrinking",
1633 ergo_format_reason("capacity higher than "
1634 "max desired capacity after Full GC")
1635 ergo_format_byte("capacity")
1636 ergo_format_byte("occupancy")
1637 ergo_format_byte_perc("max desired capacity"),
1638 capacity_after_gc, used_after_gc,
1639 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1640 shrink(shrink_bytes);
1641 }
1642 }
1643
1644
1645 HeapWord*
1646 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1647 AllocationContext_t context,
1648 bool* succeeded) {
1649 assert_at_safepoint(true /* should_be_vm_thread */);
1650
1651 *succeeded = true;
1652 // Let's attempt the allocation first.
1653 HeapWord* result =
1654 attempt_allocation_at_safepoint(word_size,
1655 context,
1656 false /* expect_null_mutator_alloc_region */);
1657 if (result != NULL) {
1658 assert(*succeeded, "sanity");
1659 return result;
1660 }
1661
1662 // In a G1 heap, we're supposed to keep allocation from failing by
1663 // incremental pauses. Therefore, at least for now, we'll favor
1664 // expansion over collection. (This might change in the future if we can
1665 // do something smarter than full collection to satisfy a failed alloc.)
1666 result = expand_and_allocate(word_size, context);
1667 if (result != NULL) {
1668 assert(*succeeded, "sanity");
1669 return result;
1670 }
1671
1672 // Expansion didn't work, we'll try to do a Full GC.
1673 bool gc_succeeded = do_collection(false, /* explicit_gc */
1674 false, /* clear_all_soft_refs */
1675 word_size);
1676 if (!gc_succeeded) {
1677 *succeeded = false;
1678 return NULL;
1679 }
1680
1681 // Retry the allocation
1682 result = attempt_allocation_at_safepoint(word_size,
1683 context,
1684 true /* expect_null_mutator_alloc_region */);
1685 if (result != NULL) {
1686 assert(*succeeded, "sanity");
1687 return result;
1688 }
1689
1690 // Then, try a Full GC that will collect all soft references.
1691 gc_succeeded = do_collection(false, /* explicit_gc */
1692 true, /* clear_all_soft_refs */
1693 word_size);
1694 if (!gc_succeeded) {
1695 *succeeded = false;
1696 return NULL;
1697 }
1698
1699 // Retry the allocation once more
1700 result = attempt_allocation_at_safepoint(word_size,
1701 context,
1702 true /* expect_null_mutator_alloc_region */);
1703 if (result != NULL) {
1704 assert(*succeeded, "sanity");
1705 return result;
1706 }
1707
1708 assert(!collector_policy()->should_clear_all_soft_refs(),
1709 "Flag should have been handled and cleared prior to this point");
1710
1711 // What else? We might try synchronous finalization later. If the total
1712 // space available is large enough for the allocation, then a more
1713 // complete compaction phase than we've tried so far might be
1714 // appropriate.
1715 assert(*succeeded, "sanity");
1716 return NULL;
1717 }
1718
1719 // Attempting to expand the heap sufficiently
1720 // to support an allocation of the given "word_size". If
1721 // successful, perform the allocation and return the address of the
1722 // allocated block, or else "NULL".
1723
1724 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1725 assert_at_safepoint(true /* should_be_vm_thread */);
1726
1727 verify_region_sets_optional();
1728
1729 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1730 ergo_verbose1(ErgoHeapSizing,
1731 "attempt heap expansion",
1732 ergo_format_reason("allocation request failed")
1733 ergo_format_byte("allocation request"),
1734 word_size * HeapWordSize);
1735 if (expand(expand_bytes)) {
1736 _hrm.verify_optional();
1737 verify_region_sets_optional();
1738 return attempt_allocation_at_safepoint(word_size,
1739 context,
1740 false /* expect_null_mutator_alloc_region */);
1741 }
1742 return NULL;
1743 }
1744
1745 bool G1CollectedHeap::expand(size_t expand_bytes) {
1746 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1747 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1748 HeapRegion::GrainBytes);
1749 ergo_verbose2(ErgoHeapSizing,
1750 "expand the heap",
1751 ergo_format_byte("requested expansion amount")
1752 ergo_format_byte("attempted expansion amount"),
1753 expand_bytes, aligned_expand_bytes);
1754
1755 if (is_maximal_no_gc()) {
1756 ergo_verbose0(ErgoHeapSizing,
1757 "did not expand the heap",
1758 ergo_format_reason("heap already fully expanded"));
1759 return false;
1760 }
1761
1762 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1763 assert(regions_to_expand > 0, "Must expand by at least one region");
1764
1765 uint expanded_by = _hrm.expand_by(regions_to_expand);
1766
1767 if (expanded_by > 0) {
1768 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1769 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1770 g1_policy()->record_new_heap_size(num_regions());
1771 } else {
1772 ergo_verbose0(ErgoHeapSizing,
1773 "did not expand the heap",
1774 ergo_format_reason("heap expansion operation failed"));
1775 // The expansion of the virtual storage space was unsuccessful.
1776 // Let's see if it was because we ran out of swap.
1777 if (G1ExitOnExpansionFailure &&
1778 _hrm.available() >= regions_to_expand) {
1779 // We had head room...
1780 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1781 }
1782 }
1783 return regions_to_expand > 0;
1784 }
1785
1786 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1787 size_t aligned_shrink_bytes =
1788 ReservedSpace::page_align_size_down(shrink_bytes);
1789 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1790 HeapRegion::GrainBytes);
1791 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1792
1793 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1794 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1795
1796 ergo_verbose3(ErgoHeapSizing,
1797 "shrink the heap",
1798 ergo_format_byte("requested shrinking amount")
1799 ergo_format_byte("aligned shrinking amount")
1800 ergo_format_byte("attempted shrinking amount"),
1801 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1802 if (num_regions_removed > 0) {
1803 g1_policy()->record_new_heap_size(num_regions());
1804 } else {
1805 ergo_verbose0(ErgoHeapSizing,
1806 "did not shrink the heap",
1807 ergo_format_reason("heap shrinking operation failed"));
1808 }
1809 }
1810
1811 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1812 verify_region_sets_optional();
1813
1814 // We should only reach here at the end of a Full GC which means we
1815 // should not not be holding to any GC alloc regions. The method
1816 // below will make sure of that and do any remaining clean up.
1817 _allocator->abandon_gc_alloc_regions();
1818
1819 // Instead of tearing down / rebuilding the free lists here, we
1820 // could instead use the remove_all_pending() method on free_list to
1821 // remove only the ones that we need to remove.
1822 tear_down_region_sets(true /* free_list_only */);
1823 shrink_helper(shrink_bytes);
1824 rebuild_region_sets(true /* free_list_only */);
1825
1826 _hrm.verify_optional();
1827 verify_region_sets_optional();
1828 }
1829
1830 // Public methods.
1831
1832 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1833 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1834 #endif // _MSC_VER
1835
1836
1837 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1838 SharedHeap(policy_),
1839 _g1_policy(policy_),
1840 _dirty_card_queue_set(false),
1841 _into_cset_dirty_card_queue_set(false),
1842 _is_alive_closure_cm(this),
1843 _is_alive_closure_stw(this),
1844 _ref_processor_cm(NULL),
1845 _ref_processor_stw(NULL),
1846 _bot_shared(NULL),
1847 _evac_failure_scan_stack(NULL),
1848 _mark_in_progress(false),
1849 _cg1r(NULL),
1850 _g1mm(NULL),
1851 _refine_cte_cl(NULL),
1852 _full_collection(false),
1853 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1854 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1855 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1856 _humongous_reclaim_candidates(),
1857 _has_humongous_reclaim_candidates(false),
1858 _free_regions_coming(false),
1859 _young_list(new YoungList(this)),
1860 _gc_time_stamp(0),
1861 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1862 _old_plab_stats(OldPLABSize, PLABWeight),
1863 _expand_heap_after_alloc_failure(true),
1864 _surviving_young_words(NULL),
1865 _old_marking_cycles_started(0),
1866 _old_marking_cycles_completed(0),
1867 _concurrent_cycle_started(false),
1868 _heap_summary_sent(false),
1869 _in_cset_fast_test(),
1870 _dirty_cards_region_list(NULL),
1871 _worker_cset_start_region(NULL),
1872 _worker_cset_start_region_time_stamp(NULL),
1873 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1874 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1875 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1876 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1877
1878 _g1h = this;
1879
1880 _allocator = G1Allocator::create_allocator(_g1h);
1881 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1882
1883 int n_queues = MAX2((int)ParallelGCThreads, 1);
1884 _task_queues = new RefToScanQueueSet(n_queues);
1885
1886 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1887 assert(n_rem_sets > 0, "Invariant.");
1888
1889 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1890 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1891 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1892
1893 for (int i = 0; i < n_queues; i++) {
1894 RefToScanQueue* q = new RefToScanQueue();
1895 q->initialize();
1896 _task_queues->register_queue(i, q);
1897 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1898 }
1899 clear_cset_start_regions();
1900
1901 // Initialize the G1EvacuationFailureALot counters and flags.
1902 NOT_PRODUCT(reset_evacuation_should_fail();)
1903
1904 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1905 }
1906
1907 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1908 size_t size,
1909 size_t translation_factor) {
1910 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1911 // Allocate a new reserved space, preferring to use large pages.
1912 ReservedSpace rs(size, preferred_page_size);
1913 G1RegionToSpaceMapper* result =
1914 G1RegionToSpaceMapper::create_mapper(rs,
1915 size,
1916 rs.alignment(),
1917 HeapRegion::GrainBytes,
1918 translation_factor,
1919 mtGC);
1920 if (TracePageSizes) {
1921 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1922 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1923 }
1924 return result;
1925 }
1926
1927 jint G1CollectedHeap::initialize() {
1928 CollectedHeap::pre_initialize();
1929 os::enable_vtime();
1930
1931 G1Log::init();
1932
1933 // Necessary to satisfy locking discipline assertions.
1934
1935 MutexLocker x(Heap_lock);
1936
1937 // We have to initialize the printer before committing the heap, as
1938 // it will be used then.
1939 _hr_printer.set_active(G1PrintHeapRegions);
1940
1941 // While there are no constraints in the GC code that HeapWordSize
1942 // be any particular value, there are multiple other areas in the
1943 // system which believe this to be true (e.g. oop->object_size in some
1944 // cases incorrectly returns the size in wordSize units rather than
1945 // HeapWordSize).
1946 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1947
1948 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1949 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1950 size_t heap_alignment = collector_policy()->heap_alignment();
1951
1952 // Ensure that the sizes are properly aligned.
1953 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1954 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1955 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1956
1957 _refine_cte_cl = new RefineCardTableEntryClosure();
1958
1959 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1960
1961 // Reserve the maximum.
1962
1963 // When compressed oops are enabled, the preferred heap base
1964 // is calculated by subtracting the requested size from the
1965 // 32Gb boundary and using the result as the base address for
1966 // heap reservation. If the requested size is not aligned to
1967 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1968 // into the ReservedHeapSpace constructor) then the actual
1969 // base of the reserved heap may end up differing from the
1970 // address that was requested (i.e. the preferred heap base).
1971 // If this happens then we could end up using a non-optimal
1972 // compressed oops mode.
1973
1974 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1975 heap_alignment);
1976
1977 // It is important to do this in a way such that concurrent readers can't
1978 // temporarily think something is in the heap. (I've actually seen this
1979 // happen in asserts: DLD.)
1980 _reserved.set_word_size(0);
1981 _reserved.set_start((HeapWord*)heap_rs.base());
1982 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1983
1984 // Create the gen rem set (and barrier set) for the entire reserved region.
1985 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1986 set_barrier_set(rem_set()->bs());
1987 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1988 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1989 return JNI_ENOMEM;
1990 }
1991
1992 // Also create a G1 rem set.
1993 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1994
1995 // Carve out the G1 part of the heap.
1996
1997 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1998 G1RegionToSpaceMapper* heap_storage =
1999 G1RegionToSpaceMapper::create_mapper(g1_rs,
2000 g1_rs.size(),
2001 UseLargePages ? os::large_page_size() : os::vm_page_size(),
2002 HeapRegion::GrainBytes,
2003 1,
2004 mtJavaHeap);
2005 heap_storage->set_mapping_changed_listener(&_listener);
2006
2007 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2008 G1RegionToSpaceMapper* bot_storage =
2009 create_aux_memory_mapper("Block offset table",
2010 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2011 G1BlockOffsetSharedArray::N_bytes);
2012
2013 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2014 G1RegionToSpaceMapper* cardtable_storage =
2015 create_aux_memory_mapper("Card table",
2016 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2017 G1BlockOffsetSharedArray::N_bytes);
2018
2019 G1RegionToSpaceMapper* card_counts_storage =
2020 create_aux_memory_mapper("Card counts table",
2021 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2022 G1BlockOffsetSharedArray::N_bytes);
2023
2024 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2025 G1RegionToSpaceMapper* prev_bitmap_storage =
2026 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
2027 G1RegionToSpaceMapper* next_bitmap_storage =
2028 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
2029
2030 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2031 g1_barrier_set()->initialize(cardtable_storage);
2032 // Do later initialization work for concurrent refinement.
2033 _cg1r->init(card_counts_storage);
2034
2035 // 6843694 - ensure that the maximum region index can fit
2036 // in the remembered set structures.
2037 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2038 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2039
2040 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2041 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2042 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2043 "too many cards per region");
2044
2045 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2046
2047 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
2048
2049 _g1h = this;
2050
2051 {
2052 HeapWord* start = _hrm.reserved().start();
2053 HeapWord* end = _hrm.reserved().end();
2054 size_t granularity = HeapRegion::GrainBytes;
2055
2056 _in_cset_fast_test.initialize(start, end, granularity);
2057 _humongous_reclaim_candidates.initialize(start, end, granularity);
2058 }
2059
2060 // Create the ConcurrentMark data structure and thread.
2061 // (Must do this late, so that "max_regions" is defined.)
2062 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2063 if (_cm == NULL || !_cm->completed_initialization()) {
2064 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2065 return JNI_ENOMEM;
2066 }
2067 _cmThread = _cm->cmThread();
2068
2069 // Initialize the from_card cache structure of HeapRegionRemSet.
2070 HeapRegionRemSet::init_heap(max_regions());
2071
2072 // Now expand into the initial heap size.
2073 if (!expand(init_byte_size)) {
2074 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2075 return JNI_ENOMEM;
2076 }
2077
2078 // Perform any initialization actions delegated to the policy.
2079 g1_policy()->init();
2080
2081 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2082 SATB_Q_FL_lock,
2083 G1SATBProcessCompletedThreshold,
2084 Shared_SATB_Q_lock);
2085
2086 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2087 DirtyCardQ_CBL_mon,
2088 DirtyCardQ_FL_lock,
2089 concurrent_g1_refine()->yellow_zone(),
2090 concurrent_g1_refine()->red_zone(),
2091 Shared_DirtyCardQ_lock);
2092
2093 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2094 DirtyCardQ_CBL_mon,
2095 DirtyCardQ_FL_lock,
2096 -1, // never trigger processing
2097 -1, // no limit on length
2098 Shared_DirtyCardQ_lock,
2099 &JavaThread::dirty_card_queue_set());
2100
2101 // Initialize the card queue set used to hold cards containing
2102 // references into the collection set.
2103 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2104 DirtyCardQ_CBL_mon,
2105 DirtyCardQ_FL_lock,
2106 -1, // never trigger processing
2107 -1, // no limit on length
2108 Shared_DirtyCardQ_lock,
2109 &JavaThread::dirty_card_queue_set());
2110
2111 // In case we're keeping closure specialization stats, initialize those
2112 // counts and that mechanism.
2113 SpecializationStats::clear();
2114
2115 // Here we allocate the dummy HeapRegion that is required by the
2116 // G1AllocRegion class.
2117 HeapRegion* dummy_region = _hrm.get_dummy_region();
2118
2119 // We'll re-use the same region whether the alloc region will
2120 // require BOT updates or not and, if it doesn't, then a non-young
2121 // region will complain that it cannot support allocations without
2122 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2123 dummy_region->set_eden();
2124 // Make sure it's full.
2125 dummy_region->set_top(dummy_region->end());
2126 G1AllocRegion::setup(this, dummy_region);
2127
2128 _allocator->init_mutator_alloc_region();
2129
2130 // Do create of the monitoring and management support so that
2131 // values in the heap have been properly initialized.
2132 _g1mm = new G1MonitoringSupport(this);
2133
2134 G1StringDedup::initialize();
2135
2136 return JNI_OK;
2137 }
2138
2139 void G1CollectedHeap::stop() {
2140 // Stop all concurrent threads. We do this to make sure these threads
2141 // do not continue to execute and access resources (e.g. gclog_or_tty)
2142 // that are destroyed during shutdown.
2143 _cg1r->stop();
2144 _cmThread->stop();
2145 if (G1StringDedup::is_enabled()) {
2146 G1StringDedup::stop();
2147 }
2148 }
2149
2150 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2151 return HeapRegion::max_region_size();
2152 }
2153
2154 void G1CollectedHeap::ref_processing_init() {
2155 // Reference processing in G1 currently works as follows:
2156 //
2157 // * There are two reference processor instances. One is
2158 // used to record and process discovered references
2159 // during concurrent marking; the other is used to
2160 // record and process references during STW pauses
2161 // (both full and incremental).
2162 // * Both ref processors need to 'span' the entire heap as
2163 // the regions in the collection set may be dotted around.
2164 //
2165 // * For the concurrent marking ref processor:
2166 // * Reference discovery is enabled at initial marking.
2167 // * Reference discovery is disabled and the discovered
2168 // references processed etc during remarking.
2169 // * Reference discovery is MT (see below).
2170 // * Reference discovery requires a barrier (see below).
2171 // * Reference processing may or may not be MT
2172 // (depending on the value of ParallelRefProcEnabled
2173 // and ParallelGCThreads).
2174 // * A full GC disables reference discovery by the CM
2175 // ref processor and abandons any entries on it's
2176 // discovered lists.
2177 //
2178 // * For the STW processor:
2179 // * Non MT discovery is enabled at the start of a full GC.
2180 // * Processing and enqueueing during a full GC is non-MT.
2181 // * During a full GC, references are processed after marking.
2182 //
2183 // * Discovery (may or may not be MT) is enabled at the start
2184 // of an incremental evacuation pause.
2185 // * References are processed near the end of a STW evacuation pause.
2186 // * For both types of GC:
2187 // * Discovery is atomic - i.e. not concurrent.
2188 // * Reference discovery will not need a barrier.
2189
2190 SharedHeap::ref_processing_init();
2191 MemRegion mr = reserved_region();
2192
2193 // Concurrent Mark ref processor
2194 _ref_processor_cm =
2195 new ReferenceProcessor(mr, // span
2196 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2197 // mt processing
2198 (int) ParallelGCThreads,
2199 // degree of mt processing
2200 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2201 // mt discovery
2202 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2203 // degree of mt discovery
2204 false,
2205 // Reference discovery is not atomic
2206 &_is_alive_closure_cm);
2207 // is alive closure
2208 // (for efficiency/performance)
2209
2210 // STW ref processor
2211 _ref_processor_stw =
2212 new ReferenceProcessor(mr, // span
2213 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2214 // mt processing
2215 MAX2((int)ParallelGCThreads, 1),
2216 // degree of mt processing
2217 (ParallelGCThreads > 1),
2218 // mt discovery
2219 MAX2((int)ParallelGCThreads, 1),
2220 // degree of mt discovery
2221 true,
2222 // Reference discovery is atomic
2223 &_is_alive_closure_stw);
2224 // is alive closure
2225 // (for efficiency/performance)
2226 }
2227
2228 size_t G1CollectedHeap::capacity() const {
2229 return _hrm.length() * HeapRegion::GrainBytes;
2230 }
2231
2232 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2233 assert(!hr->continuesHumongous(), "pre-condition");
2234 hr->reset_gc_time_stamp();
2235 if (hr->startsHumongous()) {
2236 uint first_index = hr->hrm_index() + 1;
2237 uint last_index = hr->last_hc_index();
2238 for (uint i = first_index; i < last_index; i += 1) {
2239 HeapRegion* chr = region_at(i);
2240 assert(chr->continuesHumongous(), "sanity");
2241 chr->reset_gc_time_stamp();
2242 }
2243 }
2244 }
2245
2246 #ifndef PRODUCT
2247 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2248 private:
2249 unsigned _gc_time_stamp;
2250 bool _failures;
2251
2252 public:
2253 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2254 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2255
2256 virtual bool doHeapRegion(HeapRegion* hr) {
2257 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2258 if (_gc_time_stamp != region_gc_time_stamp) {
2259 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2260 "expected %d", HR_FORMAT_PARAMS(hr),
2261 region_gc_time_stamp, _gc_time_stamp);
2262 _failures = true;
2263 }
2264 return false;
2265 }
2266
2267 bool failures() { return _failures; }
2268 };
2269
2270 void G1CollectedHeap::check_gc_time_stamps() {
2271 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2272 heap_region_iterate(&cl);
2273 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2274 }
2275 #endif // PRODUCT
2276
2277 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2278 DirtyCardQueue* into_cset_dcq,
2279 bool concurrent,
2280 uint worker_i) {
2281 // Clean cards in the hot card cache
2282 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2283 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2284
2285 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2286 size_t n_completed_buffers = 0;
2287 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2288 n_completed_buffers++;
2289 }
2290 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2291 dcqs.clear_n_completed_buffers();
2292 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2293 }
2294
2295
2296 // Computes the sum of the storage used by the various regions.
2297 size_t G1CollectedHeap::used() const {
2298 return _allocator->used();
2299 }
2300
2301 size_t G1CollectedHeap::used_unlocked() const {
2302 return _allocator->used_unlocked();
2303 }
2304
2305 class SumUsedClosure: public HeapRegionClosure {
2306 size_t _used;
2307 public:
2308 SumUsedClosure() : _used(0) {}
2309 bool doHeapRegion(HeapRegion* r) {
2310 if (!r->continuesHumongous()) {
2311 _used += r->used();
2312 }
2313 return false;
2314 }
2315 size_t result() { return _used; }
2316 };
2317
2318 size_t G1CollectedHeap::recalculate_used() const {
2319 double recalculate_used_start = os::elapsedTime();
2320
2321 SumUsedClosure blk;
2322 heap_region_iterate(&blk);
2323
2324 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2325 return blk.result();
2326 }
2327
2328 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2329 switch (cause) {
2330 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2331 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2332 case GCCause::_g1_humongous_allocation: return true;
2333 case GCCause::_update_allocation_context_stats_inc: return true;
2334 default: return false;
2335 }
2336 }
2337
2338 #ifndef PRODUCT
2339 void G1CollectedHeap::allocate_dummy_regions() {
2340 // Let's fill up most of the region
2341 size_t word_size = HeapRegion::GrainWords - 1024;
2342 // And as a result the region we'll allocate will be humongous.
2343 guarantee(isHumongous(word_size), "sanity");
2344
2345 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2346 // Let's use the existing mechanism for the allocation
2347 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2348 AllocationContext::system());
2349 if (dummy_obj != NULL) {
2350 MemRegion mr(dummy_obj, word_size);
2351 CollectedHeap::fill_with_object(mr);
2352 } else {
2353 // If we can't allocate once, we probably cannot allocate
2354 // again. Let's get out of the loop.
2355 break;
2356 }
2357 }
2358 }
2359 #endif // !PRODUCT
2360
2361 void G1CollectedHeap::increment_old_marking_cycles_started() {
2362 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2363 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2364 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2365 _old_marking_cycles_started, _old_marking_cycles_completed));
2366
2367 _old_marking_cycles_started++;
2368 }
2369
2370 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2371 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2372
2373 // We assume that if concurrent == true, then the caller is a
2374 // concurrent thread that was joined the Suspendible Thread
2375 // Set. If there's ever a cheap way to check this, we should add an
2376 // assert here.
2377
2378 // Given that this method is called at the end of a Full GC or of a
2379 // concurrent cycle, and those can be nested (i.e., a Full GC can
2380 // interrupt a concurrent cycle), the number of full collections
2381 // completed should be either one (in the case where there was no
2382 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2383 // behind the number of full collections started.
2384
2385 // This is the case for the inner caller, i.e. a Full GC.
2386 assert(concurrent ||
2387 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2388 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2389 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2390 "is inconsistent with _old_marking_cycles_completed = %u",
2391 _old_marking_cycles_started, _old_marking_cycles_completed));
2392
2393 // This is the case for the outer caller, i.e. the concurrent cycle.
2394 assert(!concurrent ||
2395 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2396 err_msg("for outer caller (concurrent cycle): "
2397 "_old_marking_cycles_started = %u "
2398 "is inconsistent with _old_marking_cycles_completed = %u",
2399 _old_marking_cycles_started, _old_marking_cycles_completed));
2400
2401 _old_marking_cycles_completed += 1;
2402
2403 // We need to clear the "in_progress" flag in the CM thread before
2404 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2405 // is set) so that if a waiter requests another System.gc() it doesn't
2406 // incorrectly see that a marking cycle is still in progress.
2407 if (concurrent) {
2408 _cmThread->clear_in_progress();
2409 }
2410
2411 // This notify_all() will ensure that a thread that called
2412 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2413 // and it's waiting for a full GC to finish will be woken up. It is
2414 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2415 FullGCCount_lock->notify_all();
2416 }
2417
2418 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2419 _concurrent_cycle_started = true;
2420 _gc_timer_cm->register_gc_start(start_time);
2421
2422 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2423 trace_heap_before_gc(_gc_tracer_cm);
2424 }
2425
2426 void G1CollectedHeap::register_concurrent_cycle_end() {
2427 if (_concurrent_cycle_started) {
2428 if (_cm->has_aborted()) {
2429 _gc_tracer_cm->report_concurrent_mode_failure();
2430 }
2431
2432 _gc_timer_cm->register_gc_end();
2433 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2434
2435 // Clear state variables to prepare for the next concurrent cycle.
2436 _concurrent_cycle_started = false;
2437 _heap_summary_sent = false;
2438 }
2439 }
2440
2441 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2442 if (_concurrent_cycle_started) {
2443 // This function can be called when:
2444 // the cleanup pause is run
2445 // the concurrent cycle is aborted before the cleanup pause.
2446 // the concurrent cycle is aborted after the cleanup pause,
2447 // but before the concurrent cycle end has been registered.
2448 // Make sure that we only send the heap information once.
2449 if (!_heap_summary_sent) {
2450 trace_heap_after_gc(_gc_tracer_cm);
2451 _heap_summary_sent = true;
2452 }
2453 }
2454 }
2455
2456 G1YCType G1CollectedHeap::yc_type() {
2457 bool is_young = g1_policy()->gcs_are_young();
2458 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2459 bool is_during_mark = mark_in_progress();
2460
2461 if (is_initial_mark) {
2462 return InitialMark;
2463 } else if (is_during_mark) {
2464 return DuringMark;
2465 } else if (is_young) {
2466 return Normal;
2467 } else {
2468 return Mixed;
2469 }
2470 }
2471
2472 void G1CollectedHeap::collect(GCCause::Cause cause) {
2473 assert_heap_not_locked();
2474
2475 uint gc_count_before;
2476 uint old_marking_count_before;
2477 uint full_gc_count_before;
2478 bool retry_gc;
2479
2480 do {
2481 retry_gc = false;
2482
2483 {
2484 MutexLocker ml(Heap_lock);
2485
2486 // Read the GC count while holding the Heap_lock
2487 gc_count_before = total_collections();
2488 full_gc_count_before = total_full_collections();
2489 old_marking_count_before = _old_marking_cycles_started;
2490 }
2491
2492 if (should_do_concurrent_full_gc(cause)) {
2493 // Schedule an initial-mark evacuation pause that will start a
2494 // concurrent cycle. We're setting word_size to 0 which means that
2495 // we are not requesting a post-GC allocation.
2496 VM_G1IncCollectionPause op(gc_count_before,
2497 0, /* word_size */
2498 true, /* should_initiate_conc_mark */
2499 g1_policy()->max_pause_time_ms(),
2500 cause);
2501 op.set_allocation_context(AllocationContext::current());
2502
2503 VMThread::execute(&op);
2504 if (!op.pause_succeeded()) {
2505 if (old_marking_count_before == _old_marking_cycles_started) {
2506 retry_gc = op.should_retry_gc();
2507 } else {
2508 // A Full GC happened while we were trying to schedule the
2509 // initial-mark GC. No point in starting a new cycle given
2510 // that the whole heap was collected anyway.
2511 }
2512
2513 if (retry_gc) {
2514 if (GC_locker::is_active_and_needs_gc()) {
2515 GC_locker::stall_until_clear();
2516 }
2517 }
2518 }
2519 } else {
2520 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2521 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2522
2523 // Schedule a standard evacuation pause. We're setting word_size
2524 // to 0 which means that we are not requesting a post-GC allocation.
2525 VM_G1IncCollectionPause op(gc_count_before,
2526 0, /* word_size */
2527 false, /* should_initiate_conc_mark */
2528 g1_policy()->max_pause_time_ms(),
2529 cause);
2530 VMThread::execute(&op);
2531 } else {
2532 // Schedule a Full GC.
2533 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2534 VMThread::execute(&op);
2535 }
2536 }
2537 } while (retry_gc);
2538 }
2539
2540 bool G1CollectedHeap::is_in(const void* p) const {
2541 if (_hrm.reserved().contains(p)) {
2542 // Given that we know that p is in the reserved space,
2543 // heap_region_containing_raw() should successfully
2544 // return the containing region.
2545 HeapRegion* hr = heap_region_containing_raw(p);
2546 return hr->is_in(p);
2547 } else {
2548 return false;
2549 }
2550 }
2551
2552 #ifdef ASSERT
2553 bool G1CollectedHeap::is_in_exact(const void* p) const {
2554 bool contains = reserved_region().contains(p);
2555 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2556 if (contains && available) {
2557 return true;
2558 } else {
2559 return false;
2560 }
2561 }
2562 #endif
2563
2564 // Iteration functions.
2565
2566 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2567
2568 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2569 ExtendedOopClosure* _cl;
2570 public:
2571 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2572 bool doHeapRegion(HeapRegion* r) {
2573 if (!r->continuesHumongous()) {
2574 r->oop_iterate(_cl);
2575 }
2576 return false;
2577 }
2578 };
2579
2580 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2581 IterateOopClosureRegionClosure blk(cl);
2582 heap_region_iterate(&blk);
2583 }
2584
2585 // Iterates an ObjectClosure over all objects within a HeapRegion.
2586
2587 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2588 ObjectClosure* _cl;
2589 public:
2590 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2591 bool doHeapRegion(HeapRegion* r) {
2592 if (! r->continuesHumongous()) {
2593 r->object_iterate(_cl);
2594 }
2595 return false;
2596 }
2597 };
2598
2599 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2600 IterateObjectClosureRegionClosure blk(cl);
2601 heap_region_iterate(&blk);
2602 }
2603
2604 // Calls a SpaceClosure on a HeapRegion.
2605
2606 class SpaceClosureRegionClosure: public HeapRegionClosure {
2607 SpaceClosure* _cl;
2608 public:
2609 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2610 bool doHeapRegion(HeapRegion* r) {
2611 _cl->do_space(r);
2612 return false;
2613 }
2614 };
2615
2616 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2617 SpaceClosureRegionClosure blk(cl);
2618 heap_region_iterate(&blk);
2619 }
2620
2621 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2622 _hrm.iterate(cl);
2623 }
2624
2625 void
2626 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2627 uint worker_id,
2628 uint num_workers,
2629 jint claim_value) const {
2630 _hrm.par_iterate(cl, worker_id, num_workers, claim_value);
2631 }
2632
2633 class ResetClaimValuesClosure: public HeapRegionClosure {
2634 public:
2635 bool doHeapRegion(HeapRegion* r) {
2636 r->set_claim_value(HeapRegion::InitialClaimValue);
2637 return false;
2638 }
2639 };
2640
2641 void G1CollectedHeap::reset_heap_region_claim_values() {
2642 ResetClaimValuesClosure blk;
2643 heap_region_iterate(&blk);
2644 }
2645
2646 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2647 ResetClaimValuesClosure blk;
2648 collection_set_iterate(&blk);
2649 }
2650
2651 #ifdef ASSERT
2652 // This checks whether all regions in the heap have the correct claim
2653 // value. I also piggy-backed on this a check to ensure that the
2654 // humongous_start_region() information on "continues humongous"
2655 // regions is correct.
2656
2657 class CheckClaimValuesClosure : public HeapRegionClosure {
2658 private:
2659 jint _claim_value;
2660 uint _failures;
2661 HeapRegion* _sh_region;
2662
2663 public:
2664 CheckClaimValuesClosure(jint claim_value) :
2665 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2666 bool doHeapRegion(HeapRegion* r) {
2667 if (r->claim_value() != _claim_value) {
2668 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2669 "claim value = %d, should be %d",
2670 HR_FORMAT_PARAMS(r),
2671 r->claim_value(), _claim_value);
2672 ++_failures;
2673 }
2674 if (!r->isHumongous()) {
2675 _sh_region = NULL;
2676 } else if (r->startsHumongous()) {
2677 _sh_region = r;
2678 } else if (r->continuesHumongous()) {
2679 if (r->humongous_start_region() != _sh_region) {
2680 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2681 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2682 HR_FORMAT_PARAMS(r),
2683 r->humongous_start_region(),
2684 _sh_region);
2685 ++_failures;
2686 }
2687 }
2688 return false;
2689 }
2690 uint failures() { return _failures; }
2691 };
2692
2693 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2694 CheckClaimValuesClosure cl(claim_value);
2695 heap_region_iterate(&cl);
2696 return cl.failures() == 0;
2697 }
2698
2699 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2700 private:
2701 jint _claim_value;
2702 uint _failures;
2703
2704 public:
2705 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2706 _claim_value(claim_value), _failures(0) { }
2707
2708 uint failures() { return _failures; }
2709
2710 bool doHeapRegion(HeapRegion* hr) {
2711 assert(hr->in_collection_set(), "how?");
2712 assert(!hr->isHumongous(), "H-region in CSet");
2713 if (hr->claim_value() != _claim_value) {
2714 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2715 "claim value = %d, should be %d",
2716 HR_FORMAT_PARAMS(hr),
2717 hr->claim_value(), _claim_value);
2718 _failures += 1;
2719 }
2720 return false;
2721 }
2722 };
2723
2724 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2725 CheckClaimValuesInCSetHRClosure cl(claim_value);
2726 collection_set_iterate(&cl);
2727 return cl.failures() == 0;
2728 }
2729 #endif // ASSERT
2730
2731 // Clear the cached CSet starting regions and (more importantly)
2732 // the time stamps. Called when we reset the GC time stamp.
2733 void G1CollectedHeap::clear_cset_start_regions() {
2734 assert(_worker_cset_start_region != NULL, "sanity");
2735 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2736
2737 int n_queues = MAX2((int)ParallelGCThreads, 1);
2738 for (int i = 0; i < n_queues; i++) {
2739 _worker_cset_start_region[i] = NULL;
2740 _worker_cset_start_region_time_stamp[i] = 0;
2741 }
2742 }
2743
2744 // Given the id of a worker, obtain or calculate a suitable
2745 // starting region for iterating over the current collection set.
2746 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2747 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2748
2749 HeapRegion* result = NULL;
2750 unsigned gc_time_stamp = get_gc_time_stamp();
2751
2752 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2753 // Cached starting region for current worker was set
2754 // during the current pause - so it's valid.
2755 // Note: the cached starting heap region may be NULL
2756 // (when the collection set is empty).
2757 result = _worker_cset_start_region[worker_i];
2758 assert(result == NULL || result->in_collection_set(), "sanity");
2759 return result;
2760 }
2761
2762 // The cached entry was not valid so let's calculate
2763 // a suitable starting heap region for this worker.
2764
2765 // We want the parallel threads to start their collection
2766 // set iteration at different collection set regions to
2767 // avoid contention.
2768 // If we have:
2769 // n collection set regions
2770 // p threads
2771 // Then thread t will start at region floor ((t * n) / p)
2772
2773 result = g1_policy()->collection_set();
2774 if (G1CollectedHeap::use_parallel_gc_threads()) {
2775 uint cs_size = g1_policy()->cset_region_length();
2776 uint active_workers = workers()->active_workers();
2777 assert(UseDynamicNumberOfGCThreads ||
2778 active_workers == workers()->total_workers(),
2779 "Unless dynamic should use total workers");
2780
2781 uint end_ind = (cs_size * worker_i) / active_workers;
2782 uint start_ind = 0;
2783
2784 if (worker_i > 0 &&
2785 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2786 // Previous workers starting region is valid
2787 // so let's iterate from there
2788 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2789 result = _worker_cset_start_region[worker_i - 1];
2790 }
2791
2792 for (uint i = start_ind; i < end_ind; i++) {
2793 result = result->next_in_collection_set();
2794 }
2795 }
2796
2797 // Note: the calculated starting heap region may be NULL
2798 // (when the collection set is empty).
2799 assert(result == NULL || result->in_collection_set(), "sanity");
2800 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2801 "should be updated only once per pause");
2802 _worker_cset_start_region[worker_i] = result;
2803 OrderAccess::storestore();
2804 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2805 return result;
2806 }
2807
2808 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2809 HeapRegion* r = g1_policy()->collection_set();
2810 while (r != NULL) {
2811 HeapRegion* next = r->next_in_collection_set();
2812 if (cl->doHeapRegion(r)) {
2813 cl->incomplete();
2814 return;
2815 }
2816 r = next;
2817 }
2818 }
2819
2820 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2821 HeapRegionClosure *cl) {
2822 if (r == NULL) {
2823 // The CSet is empty so there's nothing to do.
2824 return;
2825 }
2826
2827 assert(r->in_collection_set(),
2828 "Start region must be a member of the collection set.");
2829 HeapRegion* cur = r;
2830 while (cur != NULL) {
2831 HeapRegion* next = cur->next_in_collection_set();
2832 if (cl->doHeapRegion(cur) && false) {
2833 cl->incomplete();
2834 return;
2835 }
2836 cur = next;
2837 }
2838 cur = g1_policy()->collection_set();
2839 while (cur != r) {
2840 HeapRegion* next = cur->next_in_collection_set();
2841 if (cl->doHeapRegion(cur) && false) {
2842 cl->incomplete();
2843 return;
2844 }
2845 cur = next;
2846 }
2847 }
2848
2849 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2850 HeapRegion* result = _hrm.next_region_in_heap(from);
2851 while (result != NULL && result->isHumongous()) {
2852 result = _hrm.next_region_in_heap(result);
2853 }
2854 return result;
2855 }
2856
2857 Space* G1CollectedHeap::space_containing(const void* addr) const {
2858 return heap_region_containing(addr);
2859 }
2860
2861 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2862 Space* sp = space_containing(addr);
2863 return sp->block_start(addr);
2864 }
2865
2866 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2867 Space* sp = space_containing(addr);
2868 return sp->block_size(addr);
2869 }
2870
2871 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2872 Space* sp = space_containing(addr);
2873 return sp->block_is_obj(addr);
2874 }
2875
2876 bool G1CollectedHeap::supports_tlab_allocation() const {
2877 return true;
2878 }
2879
2880 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2881 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2882 }
2883
2884 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2885 return young_list()->eden_used_bytes();
2886 }
2887
2888 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2889 // must be smaller than the humongous object limit.
2890 size_t G1CollectedHeap::max_tlab_size() const {
2891 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2892 }
2893
2894 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2895 // Return the remaining space in the cur alloc region, but not less than
2896 // the min TLAB size.
2897
2898 // Also, this value can be at most the humongous object threshold,
2899 // since we can't allow tlabs to grow big enough to accommodate
2900 // humongous objects.
2901
2902 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2903 size_t max_tlab = max_tlab_size() * wordSize;
2904 if (hr == NULL) {
2905 return max_tlab;
2906 } else {
2907 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2908 }
2909 }
2910
2911 size_t G1CollectedHeap::max_capacity() const {
2912 return _hrm.reserved().byte_size();
2913 }
2914
2915 jlong G1CollectedHeap::millis_since_last_gc() {
2916 // assert(false, "NYI");
2917 return 0;
2918 }
2919
2920 void G1CollectedHeap::prepare_for_verify() {
2921 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2922 ensure_parsability(false);
2923 }
2924 g1_rem_set()->prepare_for_verify();
2925 }
2926
2927 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2928 VerifyOption vo) {
2929 switch (vo) {
2930 case VerifyOption_G1UsePrevMarking:
2931 return hr->obj_allocated_since_prev_marking(obj);
2932 case VerifyOption_G1UseNextMarking:
2933 return hr->obj_allocated_since_next_marking(obj);
2934 case VerifyOption_G1UseMarkWord:
2935 return false;
2936 default:
2937 ShouldNotReachHere();
2938 }
2939 return false; // keep some compilers happy
2940 }
2941
2942 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2943 switch (vo) {
2944 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2945 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2946 case VerifyOption_G1UseMarkWord: return NULL;
2947 default: ShouldNotReachHere();
2948 }
2949 return NULL; // keep some compilers happy
2950 }
2951
2952 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2953 switch (vo) {
2954 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2955 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2956 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2957 default: ShouldNotReachHere();
2958 }
2959 return false; // keep some compilers happy
2960 }
2961
2962 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2963 switch (vo) {
2964 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2965 case VerifyOption_G1UseNextMarking: return "NTAMS";
2966 case VerifyOption_G1UseMarkWord: return "NONE";
2967 default: ShouldNotReachHere();
2968 }
2969 return NULL; // keep some compilers happy
2970 }
2971
2972 class VerifyRootsClosure: public OopClosure {
2973 private:
2974 G1CollectedHeap* _g1h;
2975 VerifyOption _vo;
2976 bool _failures;
2977 public:
2978 // _vo == UsePrevMarking -> use "prev" marking information,
2979 // _vo == UseNextMarking -> use "next" marking information,
2980 // _vo == UseMarkWord -> use mark word from object header.
2981 VerifyRootsClosure(VerifyOption vo) :
2982 _g1h(G1CollectedHeap::heap()),
2983 _vo(vo),
2984 _failures(false) { }
2985
2986 bool failures() { return _failures; }
2987
2988 template <class T> void do_oop_nv(T* p) {
2989 T heap_oop = oopDesc::load_heap_oop(p);
2990 if (!oopDesc::is_null(heap_oop)) {
2991 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2992 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2993 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2994 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2995 if (_vo == VerifyOption_G1UseMarkWord) {
2996 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2997 }
2998 obj->print_on(gclog_or_tty);
2999 _failures = true;
3000 }
3001 }
3002 }
3003
3004 void do_oop(oop* p) { do_oop_nv(p); }
3005 void do_oop(narrowOop* p) { do_oop_nv(p); }
3006 };
3007
3008 class G1VerifyCodeRootOopClosure: public OopClosure {
3009 G1CollectedHeap* _g1h;
3010 OopClosure* _root_cl;
3011 nmethod* _nm;
3012 VerifyOption _vo;
3013 bool _failures;
3014
3015 template <class T> void do_oop_work(T* p) {
3016 // First verify that this root is live
3017 _root_cl->do_oop(p);
3018
3019 if (!G1VerifyHeapRegionCodeRoots) {
3020 // We're not verifying the code roots attached to heap region.
3021 return;
3022 }
3023
3024 // Don't check the code roots during marking verification in a full GC
3025 if (_vo == VerifyOption_G1UseMarkWord) {
3026 return;
3027 }
3028
3029 // Now verify that the current nmethod (which contains p) is
3030 // in the code root list of the heap region containing the
3031 // object referenced by p.
3032
3033 T heap_oop = oopDesc::load_heap_oop(p);
3034 if (!oopDesc::is_null(heap_oop)) {
3035 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3036
3037 // Now fetch the region containing the object
3038 HeapRegion* hr = _g1h->heap_region_containing(obj);
3039 HeapRegionRemSet* hrrs = hr->rem_set();
3040 // Verify that the strong code root list for this region
3041 // contains the nmethod
3042 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3043 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3044 "from nmethod "PTR_FORMAT" not in strong "
3045 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3046 p, _nm, hr->bottom(), hr->end());
3047 _failures = true;
3048 }
3049 }
3050 }
3051
3052 public:
3053 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3054 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3055
3056 void do_oop(oop* p) { do_oop_work(p); }
3057 void do_oop(narrowOop* p) { do_oop_work(p); }
3058
3059 void set_nmethod(nmethod* nm) { _nm = nm; }
3060 bool failures() { return _failures; }
3061 };
3062
3063 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3064 G1VerifyCodeRootOopClosure* _oop_cl;
3065
3066 public:
3067 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3068 _oop_cl(oop_cl) {}
3069
3070 void do_code_blob(CodeBlob* cb) {
3071 nmethod* nm = cb->as_nmethod_or_null();
3072 if (nm != NULL) {
3073 _oop_cl->set_nmethod(nm);
3074 nm->oops_do(_oop_cl);
3075 }
3076 }
3077 };
3078
3079 class YoungRefCounterClosure : public OopClosure {
3080 G1CollectedHeap* _g1h;
3081 int _count;
3082 public:
3083 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3084 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3085 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3086
3087 int count() { return _count; }
3088 void reset_count() { _count = 0; };
3089 };
3090
3091 class VerifyKlassClosure: public KlassClosure {
3092 YoungRefCounterClosure _young_ref_counter_closure;
3093 OopClosure *_oop_closure;
3094 public:
3095 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3096 void do_klass(Klass* k) {
3097 k->oops_do(_oop_closure);
3098
3099 _young_ref_counter_closure.reset_count();
3100 k->oops_do(&_young_ref_counter_closure);
3101 if (_young_ref_counter_closure.count() > 0) {
3102 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3103 }
3104 }
3105 };
3106
3107 class VerifyLivenessOopClosure: public OopClosure {
3108 G1CollectedHeap* _g1h;
3109 VerifyOption _vo;
3110 public:
3111 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3112 _g1h(g1h), _vo(vo)
3113 { }
3114 void do_oop(narrowOop *p) { do_oop_work(p); }
3115 void do_oop( oop *p) { do_oop_work(p); }
3116
3117 template <class T> void do_oop_work(T *p) {
3118 oop obj = oopDesc::load_decode_heap_oop(p);
3119 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3120 "Dead object referenced by a not dead object");
3121 }
3122 };
3123
3124 class VerifyObjsInRegionClosure: public ObjectClosure {
3125 private:
3126 G1CollectedHeap* _g1h;
3127 size_t _live_bytes;
3128 HeapRegion *_hr;
3129 VerifyOption _vo;
3130 public:
3131 // _vo == UsePrevMarking -> use "prev" marking information,
3132 // _vo == UseNextMarking -> use "next" marking information,
3133 // _vo == UseMarkWord -> use mark word from object header.
3134 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3135 : _live_bytes(0), _hr(hr), _vo(vo) {
3136 _g1h = G1CollectedHeap::heap();
3137 }
3138 void do_object(oop o) {
3139 VerifyLivenessOopClosure isLive(_g1h, _vo);
3140 assert(o != NULL, "Huh?");
3141 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3142 // If the object is alive according to the mark word,
3143 // then verify that the marking information agrees.
3144 // Note we can't verify the contra-positive of the
3145 // above: if the object is dead (according to the mark
3146 // word), it may not be marked, or may have been marked
3147 // but has since became dead, or may have been allocated
3148 // since the last marking.
3149 if (_vo == VerifyOption_G1UseMarkWord) {
3150 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3151 }
3152
3153 o->oop_iterate_no_header(&isLive);
3154 if (!_hr->obj_allocated_since_prev_marking(o)) {
3155 size_t obj_size = o->size(); // Make sure we don't overflow
3156 _live_bytes += (obj_size * HeapWordSize);
3157 }
3158 }
3159 }
3160 size_t live_bytes() { return _live_bytes; }
3161 };
3162
3163 class PrintObjsInRegionClosure : public ObjectClosure {
3164 HeapRegion *_hr;
3165 G1CollectedHeap *_g1;
3166 public:
3167 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3168 _g1 = G1CollectedHeap::heap();
3169 };
3170
3171 void do_object(oop o) {
3172 if (o != NULL) {
3173 HeapWord *start = (HeapWord *) o;
3174 size_t word_sz = o->size();
3175 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3176 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3177 (void*) o, word_sz,
3178 _g1->isMarkedPrev(o),
3179 _g1->isMarkedNext(o),
3180 _hr->obj_allocated_since_prev_marking(o));
3181 HeapWord *end = start + word_sz;
3182 HeapWord *cur;
3183 int *val;
3184 for (cur = start; cur < end; cur++) {
3185 val = (int *) cur;
3186 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3187 }
3188 }
3189 }
3190 };
3191
3192 class VerifyRegionClosure: public HeapRegionClosure {
3193 private:
3194 bool _par;
3195 VerifyOption _vo;
3196 bool _failures;
3197 public:
3198 // _vo == UsePrevMarking -> use "prev" marking information,
3199 // _vo == UseNextMarking -> use "next" marking information,
3200 // _vo == UseMarkWord -> use mark word from object header.
3201 VerifyRegionClosure(bool par, VerifyOption vo)
3202 : _par(par),
3203 _vo(vo),
3204 _failures(false) {}
3205
3206 bool failures() {
3207 return _failures;
3208 }
3209
3210 bool doHeapRegion(HeapRegion* r) {
3211 if (!r->continuesHumongous()) {
3212 bool failures = false;
3213 r->verify(_vo, &failures);
3214 if (failures) {
3215 _failures = true;
3216 } else {
3217 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3218 r->object_iterate(¬_dead_yet_cl);
3219 if (_vo != VerifyOption_G1UseNextMarking) {
3220 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3221 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3222 "max_live_bytes "SIZE_FORMAT" "
3223 "< calculated "SIZE_FORMAT,
3224 r->bottom(), r->end(),
3225 r->max_live_bytes(),
3226 not_dead_yet_cl.live_bytes());
3227 _failures = true;
3228 }
3229 } else {
3230 // When vo == UseNextMarking we cannot currently do a sanity
3231 // check on the live bytes as the calculation has not been
3232 // finalized yet.
3233 }
3234 }
3235 }
3236 return false; // stop the region iteration if we hit a failure
3237 }
3238 };
3239
3240 // This is the task used for parallel verification of the heap regions
3241
3242 class G1ParVerifyTask: public AbstractGangTask {
3243 private:
3244 G1CollectedHeap* _g1h;
3245 VerifyOption _vo;
3246 bool _failures;
3247
3248 public:
3249 // _vo == UsePrevMarking -> use "prev" marking information,
3250 // _vo == UseNextMarking -> use "next" marking information,
3251 // _vo == UseMarkWord -> use mark word from object header.
3252 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3253 AbstractGangTask("Parallel verify task"),
3254 _g1h(g1h),
3255 _vo(vo),
3256 _failures(false) { }
3257
3258 bool failures() {
3259 return _failures;
3260 }
3261
3262 void work(uint worker_id) {
3263 HandleMark hm;
3264 VerifyRegionClosure blk(true, _vo);
3265 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3266 _g1h->workers()->active_workers(),
3267 HeapRegion::ParVerifyClaimValue);
3268 if (blk.failures()) {
3269 _failures = true;
3270 }
3271 }
3272 };
3273
3274 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3275 if (SafepointSynchronize::is_at_safepoint()) {
3276 assert(Thread::current()->is_VM_thread(),
3277 "Expected to be executed serially by the VM thread at this point");
3278
3279 if (!silent) { gclog_or_tty->print("Roots "); }
3280 VerifyRootsClosure rootsCl(vo);
3281 VerifyKlassClosure klassCl(this, &rootsCl);
3282 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3283
3284 // We apply the relevant closures to all the oops in the
3285 // system dictionary, class loader data graph, the string table
3286 // and the nmethods in the code cache.
3287 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3288 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3289
3290 {
3291 G1RootProcessor root_processor(this);
3292 root_processor.process_all_roots(&rootsCl,
3293 &cldCl,
3294 &blobsCl);
3295 }
3296
3297 bool failures = rootsCl.failures() || codeRootsCl.failures();
3298
3299 if (vo != VerifyOption_G1UseMarkWord) {
3300 // If we're verifying during a full GC then the region sets
3301 // will have been torn down at the start of the GC. Therefore
3302 // verifying the region sets will fail. So we only verify
3303 // the region sets when not in a full GC.
3304 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3305 verify_region_sets();
3306 }
3307
3308 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3309 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3310 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3311 "sanity check");
3312
3313 G1ParVerifyTask task(this, vo);
3314 assert(UseDynamicNumberOfGCThreads ||
3315 workers()->active_workers() == workers()->total_workers(),
3316 "If not dynamic should be using all the workers");
3317 int n_workers = workers()->active_workers();
3318 set_par_threads(n_workers);
3319 workers()->run_task(&task);
3320 set_par_threads(0);
3321 if (task.failures()) {
3322 failures = true;
3323 }
3324
3325 // Checks that the expected amount of parallel work was done.
3326 // The implication is that n_workers is > 0.
3327 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3328 "sanity check");
3329
3330 reset_heap_region_claim_values();
3331
3332 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3333 "sanity check");
3334 } else {
3335 VerifyRegionClosure blk(false, vo);
3336 heap_region_iterate(&blk);
3337 if (blk.failures()) {
3338 failures = true;
3339 }
3340 }
3341 if (!silent) gclog_or_tty->print("RemSet ");
3342 rem_set()->verify();
3343
3344 if (G1StringDedup::is_enabled()) {
3345 if (!silent) gclog_or_tty->print("StrDedup ");
3346 G1StringDedup::verify();
3347 }
3348
3349 if (failures) {
3350 gclog_or_tty->print_cr("Heap:");
3351 // It helps to have the per-region information in the output to
3352 // help us track down what went wrong. This is why we call
3353 // print_extended_on() instead of print_on().
3354 print_extended_on(gclog_or_tty);
3355 gclog_or_tty->cr();
3356 #ifndef PRODUCT
3357 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3358 concurrent_mark()->print_reachable("at-verification-failure",
3359 vo, false /* all */);
3360 }
3361 #endif
3362 gclog_or_tty->flush();
3363 }
3364 guarantee(!failures, "there should not have been any failures");
3365 } else {
3366 if (!silent) {
3367 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3368 if (G1StringDedup::is_enabled()) {
3369 gclog_or_tty->print(", StrDedup");
3370 }
3371 gclog_or_tty->print(") ");
3372 }
3373 }
3374 }
3375
3376 void G1CollectedHeap::verify(bool silent) {
3377 verify(silent, VerifyOption_G1UsePrevMarking);
3378 }
3379
3380 double G1CollectedHeap::verify(bool guard, const char* msg) {
3381 double verify_time_ms = 0.0;
3382
3383 if (guard && total_collections() >= VerifyGCStartAt) {
3384 double verify_start = os::elapsedTime();
3385 HandleMark hm; // Discard invalid handles created during verification
3386 prepare_for_verify();
3387 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3388 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3389 }
3390
3391 return verify_time_ms;
3392 }
3393
3394 void G1CollectedHeap::verify_before_gc() {
3395 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3396 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3397 }
3398
3399 void G1CollectedHeap::verify_after_gc() {
3400 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3401 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3402 }
3403
3404 class PrintRegionClosure: public HeapRegionClosure {
3405 outputStream* _st;
3406 public:
3407 PrintRegionClosure(outputStream* st) : _st(st) {}
3408 bool doHeapRegion(HeapRegion* r) {
3409 r->print_on(_st);
3410 return false;
3411 }
3412 };
3413
3414 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3415 const HeapRegion* hr,
3416 const VerifyOption vo) const {
3417 switch (vo) {
3418 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3419 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3420 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3421 default: ShouldNotReachHere();
3422 }
3423 return false; // keep some compilers happy
3424 }
3425
3426 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3427 const VerifyOption vo) const {
3428 switch (vo) {
3429 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3430 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3431 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3432 default: ShouldNotReachHere();
3433 }
3434 return false; // keep some compilers happy
3435 }
3436
3437 void G1CollectedHeap::print_on(outputStream* st) const {
3438 st->print(" %-20s", "garbage-first heap");
3439 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3440 capacity()/K, used_unlocked()/K);
3441 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3442 _hrm.reserved().start(),
3443 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3444 _hrm.reserved().end());
3445 st->cr();
3446 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3447 uint young_regions = _young_list->length();
3448 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3449 (size_t) young_regions * HeapRegion::GrainBytes / K);
3450 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3451 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3452 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3453 st->cr();
3454 MetaspaceAux::print_on(st);
3455 }
3456
3457 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3458 print_on(st);
3459
3460 // Print the per-region information.
3461 st->cr();
3462 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3463 "HS=humongous(starts), HC=humongous(continues), "
3464 "CS=collection set, F=free, TS=gc time stamp, "
3465 "PTAMS=previous top-at-mark-start, "
3466 "NTAMS=next top-at-mark-start)");
3467 PrintRegionClosure blk(st);
3468 heap_region_iterate(&blk);
3469 }
3470
3471 void G1CollectedHeap::print_on_error(outputStream* st) const {
3472 this->CollectedHeap::print_on_error(st);
3473
3474 if (_cm != NULL) {
3475 st->cr();
3476 _cm->print_on_error(st);
3477 }
3478 }
3479
3480 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3481 if (G1CollectedHeap::use_parallel_gc_threads()) {
3482 workers()->print_worker_threads_on(st);
3483 }
3484 _cmThread->print_on(st);
3485 st->cr();
3486 _cm->print_worker_threads_on(st);
3487 _cg1r->print_worker_threads_on(st);
3488 if (G1StringDedup::is_enabled()) {
3489 G1StringDedup::print_worker_threads_on(st);
3490 }
3491 }
3492
3493 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3494 if (G1CollectedHeap::use_parallel_gc_threads()) {
3495 workers()->threads_do(tc);
3496 }
3497 tc->do_thread(_cmThread);
3498 _cg1r->threads_do(tc);
3499 if (G1StringDedup::is_enabled()) {
3500 G1StringDedup::threads_do(tc);
3501 }
3502 }
3503
3504 void G1CollectedHeap::print_tracing_info() const {
3505 // We'll overload this to mean "trace GC pause statistics."
3506 if (TraceGen0Time || TraceGen1Time) {
3507 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3508 // to that.
3509 g1_policy()->print_tracing_info();
3510 }
3511 if (G1SummarizeRSetStats) {
3512 g1_rem_set()->print_summary_info();
3513 }
3514 if (G1SummarizeConcMark) {
3515 concurrent_mark()->print_summary_info();
3516 }
3517 g1_policy()->print_yg_surv_rate_info();
3518 SpecializationStats::print();
3519 }
3520
3521 #ifndef PRODUCT
3522 // Helpful for debugging RSet issues.
3523
3524 class PrintRSetsClosure : public HeapRegionClosure {
3525 private:
3526 const char* _msg;
3527 size_t _occupied_sum;
3528
3529 public:
3530 bool doHeapRegion(HeapRegion* r) {
3531 HeapRegionRemSet* hrrs = r->rem_set();
3532 size_t occupied = hrrs->occupied();
3533 _occupied_sum += occupied;
3534
3535 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3536 HR_FORMAT_PARAMS(r));
3537 if (occupied == 0) {
3538 gclog_or_tty->print_cr(" RSet is empty");
3539 } else {
3540 hrrs->print();
3541 }
3542 gclog_or_tty->print_cr("----------");
3543 return false;
3544 }
3545
3546 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3547 gclog_or_tty->cr();
3548 gclog_or_tty->print_cr("========================================");
3549 gclog_or_tty->print_cr("%s", msg);
3550 gclog_or_tty->cr();
3551 }
3552
3553 ~PrintRSetsClosure() {
3554 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3555 gclog_or_tty->print_cr("========================================");
3556 gclog_or_tty->cr();
3557 }
3558 };
3559
3560 void G1CollectedHeap::print_cset_rsets() {
3561 PrintRSetsClosure cl("Printing CSet RSets");
3562 collection_set_iterate(&cl);
3563 }
3564
3565 void G1CollectedHeap::print_all_rsets() {
3566 PrintRSetsClosure cl("Printing All RSets");;
3567 heap_region_iterate(&cl);
3568 }
3569 #endif // PRODUCT
3570
3571 G1CollectedHeap* G1CollectedHeap::heap() {
3572 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3573 "not a garbage-first heap");
3574 return _g1h;
3575 }
3576
3577 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3578 // always_do_update_barrier = false;
3579 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3580 // Fill TLAB's and such
3581 accumulate_statistics_all_tlabs();
3582 ensure_parsability(true);
3583
3584 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3585 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3586 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3587 }
3588 }
3589
3590 void G1CollectedHeap::gc_epilogue(bool full) {
3591
3592 if (G1SummarizeRSetStats &&
3593 (G1SummarizeRSetStatsPeriod > 0) &&
3594 // we are at the end of the GC. Total collections has already been increased.
3595 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3596 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3597 }
3598
3599 // FIXME: what is this about?
3600 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3601 // is set.
3602 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3603 "derived pointer present"));
3604 // always_do_update_barrier = true;
3605
3606 resize_all_tlabs();
3607 allocation_context_stats().update(full);
3608
3609 // We have just completed a GC. Update the soft reference
3610 // policy with the new heap occupancy
3611 Universe::update_heap_info_at_gc();
3612 }
3613
3614 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3615 uint gc_count_before,
3616 bool* succeeded,
3617 GCCause::Cause gc_cause) {
3618 assert_heap_not_locked_and_not_at_safepoint();
3619 g1_policy()->record_stop_world_start();
3620 VM_G1IncCollectionPause op(gc_count_before,
3621 word_size,
3622 false, /* should_initiate_conc_mark */
3623 g1_policy()->max_pause_time_ms(),
3624 gc_cause);
3625
3626 op.set_allocation_context(AllocationContext::current());
3627 VMThread::execute(&op);
3628
3629 HeapWord* result = op.result();
3630 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3631 assert(result == NULL || ret_succeeded,
3632 "the result should be NULL if the VM did not succeed");
3633 *succeeded = ret_succeeded;
3634
3635 assert_heap_not_locked();
3636 return result;
3637 }
3638
3639 void
3640 G1CollectedHeap::doConcurrentMark() {
3641 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3642 if (!_cmThread->in_progress()) {
3643 _cmThread->set_started();
3644 CGC_lock->notify();
3645 }
3646 }
3647
3648 size_t G1CollectedHeap::pending_card_num() {
3649 size_t extra_cards = 0;
3650 JavaThread *curr = Threads::first();
3651 while (curr != NULL) {
3652 DirtyCardQueue& dcq = curr->dirty_card_queue();
3653 extra_cards += dcq.size();
3654 curr = curr->next();
3655 }
3656 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3657 size_t buffer_size = dcqs.buffer_size();
3658 size_t buffer_num = dcqs.completed_buffers_num();
3659
3660 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3661 // in bytes - not the number of 'entries'. We need to convert
3662 // into a number of cards.
3663 return (buffer_size * buffer_num + extra_cards) / oopSize;
3664 }
3665
3666 size_t G1CollectedHeap::cards_scanned() {
3667 return g1_rem_set()->cardsScanned();
3668 }
3669
3670 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3671 private:
3672 size_t _total_humongous;
3673 size_t _candidate_humongous;
3674
3675 DirtyCardQueue _dcq;
3676
3677 // We don't nominate objects with many remembered set entries, on
3678 // the assumption that such objects are likely still live.
3679 bool is_remset_small(HeapRegion* region) const {
3680 HeapRegionRemSet* const rset = region->rem_set();
3681 return G1EagerReclaimHumongousObjectsWithStaleRefs
3682 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3683 : rset->is_empty();
3684 }
3685
3686 bool is_typeArray_region(HeapRegion* region) const {
3687 return oop(region->bottom())->is_typeArray();
3688 }
3689
3690 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3691 assert(region->startsHumongous(), "Must start a humongous object");
3692
3693 // Candidate selection must satisfy the following constraints
3694 // while concurrent marking is in progress:
3695 //
3696 // * In order to maintain SATB invariants, an object must not be
3697 // reclaimed if it was allocated before the start of marking and
3698 // has not had its references scanned. Such an object must have
3699 // its references (including type metadata) scanned to ensure no
3700 // live objects are missed by the marking process. Objects
3701 // allocated after the start of concurrent marking don't need to
3702 // be scanned.
3703 //
3704 // * An object must not be reclaimed if it is on the concurrent
3705 // mark stack. Objects allocated after the start of concurrent
3706 // marking are never pushed on the mark stack.
3707 //
3708 // Nominating only objects allocated after the start of concurrent
3709 // marking is sufficient to meet both constraints. This may miss
3710 // some objects that satisfy the constraints, but the marking data
3711 // structures don't support efficiently performing the needed
3712 // additional tests or scrubbing of the mark stack.
3713 //
3714 // However, we presently only nominate is_typeArray() objects.
3715 // A humongous object containing references induces remembered
3716 // set entries on other regions. In order to reclaim such an
3717 // object, those remembered sets would need to be cleaned up.
3718 //
3719 // We also treat is_typeArray() objects specially, allowing them
3720 // to be reclaimed even if allocated before the start of
3721 // concurrent mark. For this we rely on mark stack insertion to
3722 // exclude is_typeArray() objects, preventing reclaiming an object
3723 // that is in the mark stack. We also rely on the metadata for
3724 // such objects to be built-in and so ensured to be kept live.
3725 // Frequent allocation and drop of large binary blobs is an
3726 // important use case for eager reclaim, and this special handling
3727 // may reduce needed headroom.
3728
3729 return is_typeArray_region(region) && is_remset_small(region);
3730 }
3731
3732 public:
3733 RegisterHumongousWithInCSetFastTestClosure()
3734 : _total_humongous(0),
3735 _candidate_humongous(0),
3736 _dcq(&JavaThread::dirty_card_queue_set()) {
3737 }
3738
3739 virtual bool doHeapRegion(HeapRegion* r) {
3740 if (!r->startsHumongous()) {
3741 return false;
3742 }
3743 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3744
3745 bool is_candidate = humongous_region_is_candidate(g1h, r);
3746 uint rindex = r->hrm_index();
3747 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3748 if (is_candidate) {
3749 _candidate_humongous++;
3750 g1h->register_humongous_region_with_in_cset_fast_test(rindex);
3751 // Is_candidate already filters out humongous object with large remembered sets.
3752 // If we have a humongous object with a few remembered sets, we simply flush these
3753 // remembered set entries into the DCQS. That will result in automatic
3754 // re-evaluation of their remembered set entries during the following evacuation
3755 // phase.
3756 if (!r->rem_set()->is_empty()) {
3757 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3758 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3759 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3760 HeapRegionRemSetIterator hrrs(r->rem_set());
3761 size_t card_index;
3762 while (hrrs.has_next(card_index)) {
3763 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3764 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3765 *card_ptr = CardTableModRefBS::dirty_card_val();
3766 _dcq.enqueue(card_ptr);
3767 }
3768 }
3769 r->rem_set()->clear_locked();
3770 }
3771 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3772 }
3773 _total_humongous++;
3774
3775 return false;
3776 }
3777
3778 size_t total_humongous() const { return _total_humongous; }
3779 size_t candidate_humongous() const { return _candidate_humongous; }
3780
3781 void flush_rem_set_entries() { _dcq.flush(); }
3782 };
3783
3784 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3785 if (!G1EagerReclaimHumongousObjects) {
3786 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3787 return;
3788 }
3789 double time = os::elapsed_counter();
3790
3791 // Collect reclaim candidate information and register candidates with cset.
3792 RegisterHumongousWithInCSetFastTestClosure cl;
3793 heap_region_iterate(&cl);
3794
3795 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3796 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3797 cl.total_humongous(),
3798 cl.candidate_humongous());
3799 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3800
3801 // Finally flush all remembered set entries to re-check into the global DCQS.
3802 cl.flush_rem_set_entries();
3803 }
3804
3805 void
3806 G1CollectedHeap::setup_surviving_young_words() {
3807 assert(_surviving_young_words == NULL, "pre-condition");
3808 uint array_length = g1_policy()->young_cset_region_length();
3809 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3810 if (_surviving_young_words == NULL) {
3811 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3812 "Not enough space for young surv words summary.");
3813 }
3814 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3815 #ifdef ASSERT
3816 for (uint i = 0; i < array_length; ++i) {
3817 assert( _surviving_young_words[i] == 0, "memset above" );
3818 }
3819 #endif // !ASSERT
3820 }
3821
3822 void
3823 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3824 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3825 uint array_length = g1_policy()->young_cset_region_length();
3826 for (uint i = 0; i < array_length; ++i) {
3827 _surviving_young_words[i] += surv_young_words[i];
3828 }
3829 }
3830
3831 void
3832 G1CollectedHeap::cleanup_surviving_young_words() {
3833 guarantee( _surviving_young_words != NULL, "pre-condition" );
3834 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3835 _surviving_young_words = NULL;
3836 }
3837
3838 #ifdef ASSERT
3839 class VerifyCSetClosure: public HeapRegionClosure {
3840 public:
3841 bool doHeapRegion(HeapRegion* hr) {
3842 // Here we check that the CSet region's RSet is ready for parallel
3843 // iteration. The fields that we'll verify are only manipulated
3844 // when the region is part of a CSet and is collected. Afterwards,
3845 // we reset these fields when we clear the region's RSet (when the
3846 // region is freed) so they are ready when the region is
3847 // re-allocated. The only exception to this is if there's an
3848 // evacuation failure and instead of freeing the region we leave
3849 // it in the heap. In that case, we reset these fields during
3850 // evacuation failure handling.
3851 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3852
3853 // Here's a good place to add any other checks we'd like to
3854 // perform on CSet regions.
3855 return false;
3856 }
3857 };
3858 #endif // ASSERT
3859
3860 #if TASKQUEUE_STATS
3861 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3862 st->print_raw_cr("GC Task Stats");
3863 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3864 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3865 }
3866
3867 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3868 print_taskqueue_stats_hdr(st);
3869
3870 TaskQueueStats totals;
3871 const int n = workers() != NULL ? workers()->total_workers() : 1;
3872 for (int i = 0; i < n; ++i) {
3873 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3874 totals += task_queue(i)->stats;
3875 }
3876 st->print_raw("tot "); totals.print(st); st->cr();
3877
3878 DEBUG_ONLY(totals.verify());
3879 }
3880
3881 void G1CollectedHeap::reset_taskqueue_stats() {
3882 const int n = workers() != NULL ? workers()->total_workers() : 1;
3883 for (int i = 0; i < n; ++i) {
3884 task_queue(i)->stats.reset();
3885 }
3886 }
3887 #endif // TASKQUEUE_STATS
3888
3889 void G1CollectedHeap::log_gc_header() {
3890 if (!G1Log::fine()) {
3891 return;
3892 }
3893
3894 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3895
3896 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3897 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3898 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3899
3900 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3901 }
3902
3903 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3904 if (!G1Log::fine()) {
3905 return;
3906 }
3907
3908 if (G1Log::finer()) {
3909 if (evacuation_failed()) {
3910 gclog_or_tty->print(" (to-space exhausted)");
3911 }
3912 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3913 g1_policy()->phase_times()->note_gc_end();
3914 g1_policy()->phase_times()->print(pause_time_sec);
3915 g1_policy()->print_detailed_heap_transition();
3916 } else {
3917 if (evacuation_failed()) {
3918 gclog_or_tty->print("--");
3919 }
3920 g1_policy()->print_heap_transition();
3921 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3922 }
3923 gclog_or_tty->flush();
3924 }
3925
3926 bool
3927 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3928 assert_at_safepoint(true /* should_be_vm_thread */);
3929 guarantee(!is_gc_active(), "collection is not reentrant");
3930
3931 if (GC_locker::check_active_before_gc()) {
3932 return false;
3933 }
3934
3935 _gc_timer_stw->register_gc_start();
3936
3937 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3938
3939 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3940 ResourceMark rm;
3941
3942 print_heap_before_gc();
3943 trace_heap_before_gc(_gc_tracer_stw);
3944
3945 verify_region_sets_optional();
3946 verify_dirty_young_regions();
3947
3948 // This call will decide whether this pause is an initial-mark
3949 // pause. If it is, during_initial_mark_pause() will return true
3950 // for the duration of this pause.
3951 g1_policy()->decide_on_conc_mark_initiation();
3952
3953 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3954 assert(!g1_policy()->during_initial_mark_pause() ||
3955 g1_policy()->gcs_are_young(), "sanity");
3956
3957 // We also do not allow mixed GCs during marking.
3958 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3959
3960 // Record whether this pause is an initial mark. When the current
3961 // thread has completed its logging output and it's safe to signal
3962 // the CM thread, the flag's value in the policy has been reset.
3963 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3964
3965 // Inner scope for scope based logging, timers, and stats collection
3966 {
3967 EvacuationInfo evacuation_info;
3968
3969 if (g1_policy()->during_initial_mark_pause()) {
3970 // We are about to start a marking cycle, so we increment the
3971 // full collection counter.
3972 increment_old_marking_cycles_started();
3973 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3974 }
3975
3976 _gc_tracer_stw->report_yc_type(yc_type());
3977
3978 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3979
3980 uint active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3981 workers()->active_workers() : 1);
3982 double pause_start_sec = os::elapsedTime();
3983 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3984 log_gc_header();
3985
3986 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3987 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3988
3989 // If the secondary_free_list is not empty, append it to the
3990 // free_list. No need to wait for the cleanup operation to finish;
3991 // the region allocation code will check the secondary_free_list
3992 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3993 // set, skip this step so that the region allocation code has to
3994 // get entries from the secondary_free_list.
3995 if (!G1StressConcRegionFreeing) {
3996 append_secondary_free_list_if_not_empty_with_lock();
3997 }
3998
3999 assert(check_young_list_well_formed(), "young list should be well formed");
4000 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
4001 "sanity check");
4002
4003 // Don't dynamically change the number of GC threads this early. A value of
4004 // 0 is used to indicate serial work. When parallel work is done,
4005 // it will be set.
4006
4007 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4008 IsGCActiveMark x;
4009
4010 gc_prologue(false);
4011 increment_total_collections(false /* full gc */);
4012 increment_gc_time_stamp();
4013
4014 verify_before_gc();
4015 check_bitmaps("GC Start");
4016
4017 COMPILER2_PRESENT(DerivedPointerTable::clear());
4018
4019 // Please see comment in g1CollectedHeap.hpp and
4020 // G1CollectedHeap::ref_processing_init() to see how
4021 // reference processing currently works in G1.
4022
4023 // Enable discovery in the STW reference processor
4024 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4025 true /*verify_no_refs*/);
4026
4027 {
4028 // We want to temporarily turn off discovery by the
4029 // CM ref processor, if necessary, and turn it back on
4030 // on again later if we do. Using a scoped
4031 // NoRefDiscovery object will do this.
4032 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4033
4034 // Forget the current alloc region (we might even choose it to be part
4035 // of the collection set!).
4036 _allocator->release_mutator_alloc_region();
4037
4038 // We should call this after we retire the mutator alloc
4039 // region(s) so that all the ALLOC / RETIRE events are generated
4040 // before the start GC event.
4041 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4042
4043 // This timing is only used by the ergonomics to handle our pause target.
4044 // It is unclear why this should not include the full pause. We will
4045 // investigate this in CR 7178365.
4046 //
4047 // Preserving the old comment here if that helps the investigation:
4048 //
4049 // The elapsed time induced by the start time below deliberately elides
4050 // the possible verification above.
4051 double sample_start_time_sec = os::elapsedTime();
4052
4053 #if YOUNG_LIST_VERBOSE
4054 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4055 _young_list->print();
4056 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4057 #endif // YOUNG_LIST_VERBOSE
4058
4059 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4060
4061 double scan_wait_start = os::elapsedTime();
4062 // We have to wait until the CM threads finish scanning the
4063 // root regions as it's the only way to ensure that all the
4064 // objects on them have been correctly scanned before we start
4065 // moving them during the GC.
4066 bool waited = _cm->root_regions()->wait_until_scan_finished();
4067 double wait_time_ms = 0.0;
4068 if (waited) {
4069 double scan_wait_end = os::elapsedTime();
4070 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4071 }
4072 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4073
4074 #if YOUNG_LIST_VERBOSE
4075 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4076 _young_list->print();
4077 #endif // YOUNG_LIST_VERBOSE
4078
4079 if (g1_policy()->during_initial_mark_pause()) {
4080 concurrent_mark()->checkpointRootsInitialPre();
4081 }
4082
4083 #if YOUNG_LIST_VERBOSE
4084 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4085 _young_list->print();
4086 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4087 #endif // YOUNG_LIST_VERBOSE
4088
4089 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4090
4091 register_humongous_regions_with_in_cset_fast_test();
4092
4093 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4094
4095 _cm->note_start_of_gc();
4096 // We should not verify the per-thread SATB buffers given that
4097 // we have not filtered them yet (we'll do so during the
4098 // GC). We also call this after finalize_cset() to
4099 // ensure that the CSet has been finalized.
4100 _cm->verify_no_cset_oops(true /* verify_stacks */,
4101 true /* verify_enqueued_buffers */,
4102 false /* verify_thread_buffers */,
4103 true /* verify_fingers */);
4104
4105 if (_hr_printer.is_active()) {
4106 HeapRegion* hr = g1_policy()->collection_set();
4107 while (hr != NULL) {
4108 _hr_printer.cset(hr);
4109 hr = hr->next_in_collection_set();
4110 }
4111 }
4112
4113 #ifdef ASSERT
4114 VerifyCSetClosure cl;
4115 collection_set_iterate(&cl);
4116 #endif // ASSERT
4117
4118 setup_surviving_young_words();
4119
4120 // Initialize the GC alloc regions.
4121 _allocator->init_gc_alloc_regions(evacuation_info);
4122
4123 // Actually do the work...
4124 evacuate_collection_set(evacuation_info);
4125
4126 // We do this to mainly verify the per-thread SATB buffers
4127 // (which have been filtered by now) since we didn't verify
4128 // them earlier. No point in re-checking the stacks / enqueued
4129 // buffers given that the CSet has not changed since last time
4130 // we checked.
4131 _cm->verify_no_cset_oops(false /* verify_stacks */,
4132 false /* verify_enqueued_buffers */,
4133 true /* verify_thread_buffers */,
4134 true /* verify_fingers */);
4135
4136 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4137
4138 eagerly_reclaim_humongous_regions();
4139
4140 g1_policy()->clear_collection_set();
4141
4142 cleanup_surviving_young_words();
4143
4144 // Start a new incremental collection set for the next pause.
4145 g1_policy()->start_incremental_cset_building();
4146
4147 clear_cset_fast_test();
4148
4149 _young_list->reset_sampled_info();
4150
4151 // Don't check the whole heap at this point as the
4152 // GC alloc regions from this pause have been tagged
4153 // as survivors and moved on to the survivor list.
4154 // Survivor regions will fail the !is_young() check.
4155 assert(check_young_list_empty(false /* check_heap */),
4156 "young list should be empty");
4157
4158 #if YOUNG_LIST_VERBOSE
4159 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4160 _young_list->print();
4161 #endif // YOUNG_LIST_VERBOSE
4162
4163 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4164 _young_list->first_survivor_region(),
4165 _young_list->last_survivor_region());
4166
4167 _young_list->reset_auxilary_lists();
4168
4169 if (evacuation_failed()) {
4170 _allocator->set_used(recalculate_used());
4171 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4172 for (uint i = 0; i < n_queues; i++) {
4173 if (_evacuation_failed_info_array[i].has_failed()) {
4174 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4175 }
4176 }
4177 } else {
4178 // The "used" of the the collection set have already been subtracted
4179 // when they were freed. Add in the bytes evacuated.
4180 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4181 }
4182
4183 if (g1_policy()->during_initial_mark_pause()) {
4184 // We have to do this before we notify the CM threads that
4185 // they can start working to make sure that all the
4186 // appropriate initialization is done on the CM object.
4187 concurrent_mark()->checkpointRootsInitialPost();
4188 set_marking_started();
4189 // Note that we don't actually trigger the CM thread at
4190 // this point. We do that later when we're sure that
4191 // the current thread has completed its logging output.
4192 }
4193
4194 allocate_dummy_regions();
4195
4196 #if YOUNG_LIST_VERBOSE
4197 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4198 _young_list->print();
4199 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4200 #endif // YOUNG_LIST_VERBOSE
4201
4202 _allocator->init_mutator_alloc_region();
4203
4204 {
4205 size_t expand_bytes = g1_policy()->expansion_amount();
4206 if (expand_bytes > 0) {
4207 size_t bytes_before = capacity();
4208 // No need for an ergo verbose message here,
4209 // expansion_amount() does this when it returns a value > 0.
4210 if (!expand(expand_bytes)) {
4211 // We failed to expand the heap. Cannot do anything about it.
4212 }
4213 }
4214 }
4215
4216 // We redo the verification but now wrt to the new CSet which
4217 // has just got initialized after the previous CSet was freed.
4218 _cm->verify_no_cset_oops(true /* verify_stacks */,
4219 true /* verify_enqueued_buffers */,
4220 true /* verify_thread_buffers */,
4221 true /* verify_fingers */);
4222 _cm->note_end_of_gc();
4223
4224 // This timing is only used by the ergonomics to handle our pause target.
4225 // It is unclear why this should not include the full pause. We will
4226 // investigate this in CR 7178365.
4227 double sample_end_time_sec = os::elapsedTime();
4228 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4229 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4230
4231 MemoryService::track_memory_usage();
4232
4233 // In prepare_for_verify() below we'll need to scan the deferred
4234 // update buffers to bring the RSets up-to-date if
4235 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4236 // the update buffers we'll probably need to scan cards on the
4237 // regions we just allocated to (i.e., the GC alloc
4238 // regions). However, during the last GC we called
4239 // set_saved_mark() on all the GC alloc regions, so card
4240 // scanning might skip the [saved_mark_word()...top()] area of
4241 // those regions (i.e., the area we allocated objects into
4242 // during the last GC). But it shouldn't. Given that
4243 // saved_mark_word() is conditional on whether the GC time stamp
4244 // on the region is current or not, by incrementing the GC time
4245 // stamp here we invalidate all the GC time stamps on all the
4246 // regions and saved_mark_word() will simply return top() for
4247 // all the regions. This is a nicer way of ensuring this rather
4248 // than iterating over the regions and fixing them. In fact, the
4249 // GC time stamp increment here also ensures that
4250 // saved_mark_word() will return top() between pauses, i.e.,
4251 // during concurrent refinement. So we don't need the
4252 // is_gc_active() check to decided which top to use when
4253 // scanning cards (see CR 7039627).
4254 increment_gc_time_stamp();
4255
4256 verify_after_gc();
4257 check_bitmaps("GC End");
4258
4259 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4260 ref_processor_stw()->verify_no_references_recorded();
4261
4262 // CM reference discovery will be re-enabled if necessary.
4263 }
4264
4265 // We should do this after we potentially expand the heap so
4266 // that all the COMMIT events are generated before the end GC
4267 // event, and after we retire the GC alloc regions so that all
4268 // RETIRE events are generated before the end GC event.
4269 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4270
4271 #ifdef TRACESPINNING
4272 ParallelTaskTerminator::print_termination_counts();
4273 #endif
4274
4275 gc_epilogue(false);
4276 }
4277
4278 // Print the remainder of the GC log output.
4279 log_gc_footer(os::elapsedTime() - pause_start_sec);
4280
4281 // It is not yet to safe to tell the concurrent mark to
4282 // start as we have some optional output below. We don't want the
4283 // output from the concurrent mark thread interfering with this
4284 // logging output either.
4285
4286 _hrm.verify_optional();
4287 verify_region_sets_optional();
4288
4289 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4290 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4291
4292 print_heap_after_gc();
4293 trace_heap_after_gc(_gc_tracer_stw);
4294
4295 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4296 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4297 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4298 // before any GC notifications are raised.
4299 g1mm()->update_sizes();
4300
4301 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4302 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4303 _gc_timer_stw->register_gc_end();
4304 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4305 }
4306 // It should now be safe to tell the concurrent mark thread to start
4307 // without its logging output interfering with the logging output
4308 // that came from the pause.
4309
4310 if (should_start_conc_mark) {
4311 // CAUTION: after the doConcurrentMark() call below,
4312 // the concurrent marking thread(s) could be running
4313 // concurrently with us. Make sure that anything after
4314 // this point does not assume that we are the only GC thread
4315 // running. Note: of course, the actual marking work will
4316 // not start until the safepoint itself is released in
4317 // SuspendibleThreadSet::desynchronize().
4318 doConcurrentMark();
4319 }
4320
4321 return true;
4322 }
4323
4324 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4325 _drain_in_progress = false;
4326 set_evac_failure_closure(cl);
4327 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4328 }
4329
4330 void G1CollectedHeap::finalize_for_evac_failure() {
4331 assert(_evac_failure_scan_stack != NULL &&
4332 _evac_failure_scan_stack->length() == 0,
4333 "Postcondition");
4334 assert(!_drain_in_progress, "Postcondition");
4335 delete _evac_failure_scan_stack;
4336 _evac_failure_scan_stack = NULL;
4337 }
4338
4339 void G1CollectedHeap::remove_self_forwarding_pointers() {
4340 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4341
4342 double remove_self_forwards_start = os::elapsedTime();
4343
4344 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4345
4346 if (G1CollectedHeap::use_parallel_gc_threads()) {
4347 set_par_threads();
4348 workers()->run_task(&rsfp_task);
4349 set_par_threads(0);
4350 } else {
4351 rsfp_task.work(0);
4352 }
4353
4354 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4355
4356 // Reset the claim values in the regions in the collection set.
4357 reset_cset_heap_region_claim_values();
4358
4359 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4360
4361 // Now restore saved marks, if any.
4362 assert(_objs_with_preserved_marks.size() ==
4363 _preserved_marks_of_objs.size(), "Both or none.");
4364 while (!_objs_with_preserved_marks.is_empty()) {
4365 oop obj = _objs_with_preserved_marks.pop();
4366 markOop m = _preserved_marks_of_objs.pop();
4367 obj->set_mark(m);
4368 }
4369 _objs_with_preserved_marks.clear(true);
4370 _preserved_marks_of_objs.clear(true);
4371
4372 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4373 }
4374
4375 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4376 _evac_failure_scan_stack->push(obj);
4377 }
4378
4379 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4380 assert(_evac_failure_scan_stack != NULL, "precondition");
4381
4382 while (_evac_failure_scan_stack->length() > 0) {
4383 oop obj = _evac_failure_scan_stack->pop();
4384 _evac_failure_closure->set_region(heap_region_containing(obj));
4385 obj->oop_iterate_backwards(_evac_failure_closure);
4386 }
4387 }
4388
4389 oop
4390 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4391 oop old) {
4392 assert(obj_in_cs(old),
4393 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4394 (HeapWord*) old));
4395 markOop m = old->mark();
4396 oop forward_ptr = old->forward_to_atomic(old);
4397 if (forward_ptr == NULL) {
4398 // Forward-to-self succeeded.
4399 assert(_par_scan_state != NULL, "par scan state");
4400 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4401 uint queue_num = _par_scan_state->queue_num();
4402
4403 _evacuation_failed = true;
4404 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4405 if (_evac_failure_closure != cl) {
4406 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4407 assert(!_drain_in_progress,
4408 "Should only be true while someone holds the lock.");
4409 // Set the global evac-failure closure to the current thread's.
4410 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4411 set_evac_failure_closure(cl);
4412 // Now do the common part.
4413 handle_evacuation_failure_common(old, m);
4414 // Reset to NULL.
4415 set_evac_failure_closure(NULL);
4416 } else {
4417 // The lock is already held, and this is recursive.
4418 assert(_drain_in_progress, "This should only be the recursive case.");
4419 handle_evacuation_failure_common(old, m);
4420 }
4421 return old;
4422 } else {
4423 // Forward-to-self failed. Either someone else managed to allocate
4424 // space for this object (old != forward_ptr) or they beat us in
4425 // self-forwarding it (old == forward_ptr).
4426 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4427 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4428 "should not be in the CSet",
4429 (HeapWord*) old, (HeapWord*) forward_ptr));
4430 return forward_ptr;
4431 }
4432 }
4433
4434 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4435 preserve_mark_if_necessary(old, m);
4436
4437 HeapRegion* r = heap_region_containing(old);
4438 if (!r->evacuation_failed()) {
4439 r->set_evacuation_failed(true);
4440 _hr_printer.evac_failure(r);
4441 }
4442
4443 push_on_evac_failure_scan_stack(old);
4444
4445 if (!_drain_in_progress) {
4446 // prevent recursion in copy_to_survivor_space()
4447 _drain_in_progress = true;
4448 drain_evac_failure_scan_stack();
4449 _drain_in_progress = false;
4450 }
4451 }
4452
4453 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4454 assert(evacuation_failed(), "Oversaving!");
4455 // We want to call the "for_promotion_failure" version only in the
4456 // case of a promotion failure.
4457 if (m->must_be_preserved_for_promotion_failure(obj)) {
4458 _objs_with_preserved_marks.push(obj);
4459 _preserved_marks_of_objs.push(m);
4460 }
4461 }
4462
4463 void G1ParCopyHelper::mark_object(oop obj) {
4464 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4465
4466 // We know that the object is not moving so it's safe to read its size.
4467 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4468 }
4469
4470 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4471 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4472 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4473 assert(from_obj != to_obj, "should not be self-forwarded");
4474
4475 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4476 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4477
4478 // The object might be in the process of being copied by another
4479 // worker so we cannot trust that its to-space image is
4480 // well-formed. So we have to read its size from its from-space
4481 // image which we know should not be changing.
4482 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4483 }
4484
4485 template <class T>
4486 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4487 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4488 _scanned_klass->record_modified_oops();
4489 }
4490 }
4491
4492 template <G1Barrier barrier, G1Mark do_mark_object>
4493 template <class T>
4494 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4495 T heap_oop = oopDesc::load_heap_oop(p);
4496
4497 if (oopDesc::is_null(heap_oop)) {
4498 return;
4499 }
4500
4501 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4502
4503 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4504
4505 const InCSetState state = _g1->in_cset_state(obj);
4506 if (state.is_in_cset()) {
4507 oop forwardee;
4508 markOop m = obj->mark();
4509 if (m->is_marked()) {
4510 forwardee = (oop) m->decode_pointer();
4511 } else {
4512 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4513 }
4514 assert(forwardee != NULL, "forwardee should not be NULL");
4515 oopDesc::encode_store_heap_oop(p, forwardee);
4516 if (do_mark_object != G1MarkNone && forwardee != obj) {
4517 // If the object is self-forwarded we don't need to explicitly
4518 // mark it, the evacuation failure protocol will do so.
4519 mark_forwarded_object(obj, forwardee);
4520 }
4521
4522 if (barrier == G1BarrierKlass) {
4523 do_klass_barrier(p, forwardee);
4524 }
4525 } else {
4526 if (state.is_humongous()) {
4527 _g1->set_humongous_is_live(obj);
4528 }
4529 // The object is not in collection set. If we're a root scanning
4530 // closure during an initial mark pause then attempt to mark the object.
4531 if (do_mark_object == G1MarkFromRoot) {
4532 mark_object(obj);
4533 }
4534 }
4535
4536 if (barrier == G1BarrierEvac) {
4537 _par_scan_state->update_rs(_from, p, _worker_id);
4538 }
4539 }
4540
4541 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4542 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4543
4544 class G1ParEvacuateFollowersClosure : public VoidClosure {
4545 protected:
4546 G1CollectedHeap* _g1h;
4547 G1ParScanThreadState* _par_scan_state;
4548 RefToScanQueueSet* _queues;
4549 ParallelTaskTerminator* _terminator;
4550
4551 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4552 RefToScanQueueSet* queues() { return _queues; }
4553 ParallelTaskTerminator* terminator() { return _terminator; }
4554
4555 public:
4556 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4557 G1ParScanThreadState* par_scan_state,
4558 RefToScanQueueSet* queues,
4559 ParallelTaskTerminator* terminator)
4560 : _g1h(g1h), _par_scan_state(par_scan_state),
4561 _queues(queues), _terminator(terminator) {}
4562
4563 void do_void();
4564
4565 private:
4566 inline bool offer_termination();
4567 };
4568
4569 bool G1ParEvacuateFollowersClosure::offer_termination() {
4570 G1ParScanThreadState* const pss = par_scan_state();
4571 pss->start_term_time();
4572 const bool res = terminator()->offer_termination();
4573 pss->end_term_time();
4574 return res;
4575 }
4576
4577 void G1ParEvacuateFollowersClosure::do_void() {
4578 G1ParScanThreadState* const pss = par_scan_state();
4579 pss->trim_queue();
4580 do {
4581 pss->steal_and_trim_queue(queues());
4582 } while (!offer_termination());
4583 }
4584
4585 class G1KlassScanClosure : public KlassClosure {
4586 G1ParCopyHelper* _closure;
4587 bool _process_only_dirty;
4588 int _count;
4589 public:
4590 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4591 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4592 void do_klass(Klass* klass) {
4593 // If the klass has not been dirtied we know that there's
4594 // no references into the young gen and we can skip it.
4595 if (!_process_only_dirty || klass->has_modified_oops()) {
4596 // Clean the klass since we're going to scavenge all the metadata.
4597 klass->clear_modified_oops();
4598
4599 // Tell the closure that this klass is the Klass to scavenge
4600 // and is the one to dirty if oops are left pointing into the young gen.
4601 _closure->set_scanned_klass(klass);
4602
4603 klass->oops_do(_closure);
4604
4605 _closure->set_scanned_klass(NULL);
4606 }
4607 _count++;
4608 }
4609 };
4610
4611 class G1ParTask : public AbstractGangTask {
4612 protected:
4613 G1CollectedHeap* _g1h;
4614 RefToScanQueueSet *_queues;
4615 G1RootProcessor* _root_processor;
4616 ParallelTaskTerminator _terminator;
4617 uint _n_workers;
4618
4619 Mutex _stats_lock;
4620 Mutex* stats_lock() { return &_stats_lock; }
4621
4622 public:
4623 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4624 : AbstractGangTask("G1 collection"),
4625 _g1h(g1h),
4626 _queues(task_queues),
4627 _root_processor(root_processor),
4628 _terminator(0, _queues),
4629 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4630 {}
4631
4632 RefToScanQueueSet* queues() { return _queues; }
4633
4634 RefToScanQueue *work_queue(int i) {
4635 return queues()->queue(i);
4636 }
4637
4638 ParallelTaskTerminator* terminator() { return &_terminator; }
4639
4640 virtual void set_for_termination(int active_workers) {
4641 _root_processor->set_num_workers(active_workers);
4642 terminator()->reset_for_reuse(active_workers);
4643 _n_workers = active_workers;
4644 }
4645
4646 // Helps out with CLD processing.
4647 //
4648 // During InitialMark we need to:
4649 // 1) Scavenge all CLDs for the young GC.
4650 // 2) Mark all objects directly reachable from strong CLDs.
4651 template <G1Mark do_mark_object>
4652 class G1CLDClosure : public CLDClosure {
4653 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4654 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4655 G1KlassScanClosure _klass_in_cld_closure;
4656 bool _claim;
4657
4658 public:
4659 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4660 bool only_young, bool claim)
4661 : _oop_closure(oop_closure),
4662 _oop_in_klass_closure(oop_closure->g1(),
4663 oop_closure->pss(),
4664 oop_closure->rp()),
4665 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4666 _claim(claim) {
4667
4668 }
4669
4670 void do_cld(ClassLoaderData* cld) {
4671 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4672 }
4673 };
4674
4675 void work(uint worker_id) {
4676 if (worker_id >= _n_workers) return; // no work needed this round
4677
4678 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4679
4680 {
4681 ResourceMark rm;
4682 HandleMark hm;
4683
4684 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4685
4686 G1ParScanThreadState pss(_g1h, worker_id, rp);
4687 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4688
4689 pss.set_evac_failure_closure(&evac_failure_cl);
4690
4691 bool only_young = _g1h->g1_policy()->gcs_are_young();
4692
4693 // Non-IM young GC.
4694 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4695 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4696 only_young, // Only process dirty klasses.
4697 false); // No need to claim CLDs.
4698 // IM young GC.
4699 // Strong roots closures.
4700 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4701 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4702 false, // Process all klasses.
4703 true); // Need to claim CLDs.
4704 // Weak roots closures.
4705 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4706 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4707 false, // Process all klasses.
4708 true); // Need to claim CLDs.
4709
4710 OopClosure* strong_root_cl;
4711 OopClosure* weak_root_cl;
4712 CLDClosure* strong_cld_cl;
4713 CLDClosure* weak_cld_cl;
4714
4715 bool trace_metadata = false;
4716
4717 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4718 // We also need to mark copied objects.
4719 strong_root_cl = &scan_mark_root_cl;
4720 strong_cld_cl = &scan_mark_cld_cl;
4721 if (ClassUnloadingWithConcurrentMark) {
4722 weak_root_cl = &scan_mark_weak_root_cl;
4723 weak_cld_cl = &scan_mark_weak_cld_cl;
4724 trace_metadata = true;
4725 } else {
4726 weak_root_cl = &scan_mark_root_cl;
4727 weak_cld_cl = &scan_mark_cld_cl;
4728 }
4729 } else {
4730 strong_root_cl = &scan_only_root_cl;
4731 weak_root_cl = &scan_only_root_cl;
4732 strong_cld_cl = &scan_only_cld_cl;
4733 weak_cld_cl = &scan_only_cld_cl;
4734 }
4735
4736 pss.start_strong_roots();
4737
4738 _root_processor->evacuate_roots(strong_root_cl,
4739 weak_root_cl,
4740 strong_cld_cl,
4741 weak_cld_cl,
4742 trace_metadata,
4743 worker_id);
4744
4745 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4746 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4747 weak_root_cl,
4748 worker_id);
4749 pss.end_strong_roots();
4750
4751 {
4752 double start = os::elapsedTime();
4753 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4754 evac.do_void();
4755 double elapsed_sec = os::elapsedTime() - start;
4756 double term_sec = pss.term_time();
4757 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4758 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4759 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4760 }
4761 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4762 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4763
4764 if (ParallelGCVerbose) {
4765 MutexLocker x(stats_lock());
4766 pss.print_termination_stats(worker_id);
4767 }
4768
4769 assert(pss.queue_is_empty(), "should be empty");
4770
4771 // Close the inner scope so that the ResourceMark and HandleMark
4772 // destructors are executed here and are included as part of the
4773 // "GC Worker Time".
4774 }
4775 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4776 }
4777 };
4778
4779 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4780 private:
4781 BoolObjectClosure* _is_alive;
4782 int _initial_string_table_size;
4783 int _initial_symbol_table_size;
4784
4785 bool _process_strings;
4786 int _strings_processed;
4787 int _strings_removed;
4788
4789 bool _process_symbols;
4790 int _symbols_processed;
4791 int _symbols_removed;
4792
4793 bool _do_in_parallel;
4794 public:
4795 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4796 AbstractGangTask("String/Symbol Unlinking"),
4797 _is_alive(is_alive),
4798 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4799 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4800 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4801
4802 _initial_string_table_size = StringTable::the_table()->table_size();
4803 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4804 if (process_strings) {
4805 StringTable::clear_parallel_claimed_index();
4806 }
4807 if (process_symbols) {
4808 SymbolTable::clear_parallel_claimed_index();
4809 }
4810 }
4811
4812 ~G1StringSymbolTableUnlinkTask() {
4813 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4814 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4815 StringTable::parallel_claimed_index(), _initial_string_table_size));
4816 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4817 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4818 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4819
4820 if (G1TraceStringSymbolTableScrubbing) {
4821 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4822 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4823 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4824 strings_processed(), strings_removed(),
4825 symbols_processed(), symbols_removed());
4826 }
4827 }
4828
4829 void work(uint worker_id) {
4830 if (_do_in_parallel) {
4831 int strings_processed = 0;
4832 int strings_removed = 0;
4833 int symbols_processed = 0;
4834 int symbols_removed = 0;
4835 if (_process_strings) {
4836 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4837 Atomic::add(strings_processed, &_strings_processed);
4838 Atomic::add(strings_removed, &_strings_removed);
4839 }
4840 if (_process_symbols) {
4841 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4842 Atomic::add(symbols_processed, &_symbols_processed);
4843 Atomic::add(symbols_removed, &_symbols_removed);
4844 }
4845 } else {
4846 if (_process_strings) {
4847 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
4848 }
4849 if (_process_symbols) {
4850 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
4851 }
4852 }
4853 }
4854
4855 size_t strings_processed() const { return (size_t)_strings_processed; }
4856 size_t strings_removed() const { return (size_t)_strings_removed; }
4857
4858 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4859 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4860 };
4861
4862 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4863 private:
4864 static Monitor* _lock;
4865
4866 BoolObjectClosure* const _is_alive;
4867 const bool _unloading_occurred;
4868 const uint _num_workers;
4869
4870 // Variables used to claim nmethods.
4871 nmethod* _first_nmethod;
4872 volatile nmethod* _claimed_nmethod;
4873
4874 // The list of nmethods that need to be processed by the second pass.
4875 volatile nmethod* _postponed_list;
4876 volatile uint _num_entered_barrier;
4877
4878 public:
4879 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4880 _is_alive(is_alive),
4881 _unloading_occurred(unloading_occurred),
4882 _num_workers(num_workers),
4883 _first_nmethod(NULL),
4884 _claimed_nmethod(NULL),
4885 _postponed_list(NULL),
4886 _num_entered_barrier(0)
4887 {
4888 nmethod::increase_unloading_clock();
4889 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
4890 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4891 }
4892
4893 ~G1CodeCacheUnloadingTask() {
4894 CodeCache::verify_clean_inline_caches();
4895
4896 CodeCache::set_needs_cache_clean(false);
4897 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4898
4899 CodeCache::verify_icholder_relocations();
4900 }
4901
4902 private:
4903 void add_to_postponed_list(nmethod* nm) {
4904 nmethod* old;
4905 do {
4906 old = (nmethod*)_postponed_list;
4907 nm->set_unloading_next(old);
4908 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4909 }
4910
4911 void clean_nmethod(nmethod* nm) {
4912 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4913
4914 if (postponed) {
4915 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4916 add_to_postponed_list(nm);
4917 }
4918
4919 // Mark that this thread has been cleaned/unloaded.
4920 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4921 nm->set_unloading_clock(nmethod::global_unloading_clock());
4922 }
4923
4924 void clean_nmethod_postponed(nmethod* nm) {
4925 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4926 }
4927
4928 static const int MaxClaimNmethods = 16;
4929
4930 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4931 nmethod* first;
4932 nmethod* last;
4933
4934 do {
4935 *num_claimed_nmethods = 0;
4936
4937 first = last = (nmethod*)_claimed_nmethod;
4938
4939 if (first != NULL) {
4940 for (int i = 0; i < MaxClaimNmethods; i++) {
4941 last = CodeCache::alive_nmethod(CodeCache::next(last));
4942
4943 if (last == NULL) {
4944 break;
4945 }
4946
4947 claimed_nmethods[i] = last;
4948 (*num_claimed_nmethods)++;
4949 }
4950 }
4951
4952 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
4953 }
4954
4955 nmethod* claim_postponed_nmethod() {
4956 nmethod* claim;
4957 nmethod* next;
4958
4959 do {
4960 claim = (nmethod*)_postponed_list;
4961 if (claim == NULL) {
4962 return NULL;
4963 }
4964
4965 next = claim->unloading_next();
4966
4967 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4968
4969 return claim;
4970 }
4971
4972 public:
4973 // Mark that we're done with the first pass of nmethod cleaning.
4974 void barrier_mark(uint worker_id) {
4975 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4976 _num_entered_barrier++;
4977 if (_num_entered_barrier == _num_workers) {
4978 ml.notify_all();
4979 }
4980 }
4981
4982 // See if we have to wait for the other workers to
4983 // finish their first-pass nmethod cleaning work.
4984 void barrier_wait(uint worker_id) {
4985 if (_num_entered_barrier < _num_workers) {
4986 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4987 while (_num_entered_barrier < _num_workers) {
4988 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4989 }
4990 }
4991 }
4992
4993 // Cleaning and unloading of nmethods. Some work has to be postponed
4994 // to the second pass, when we know which nmethods survive.
4995 void work_first_pass(uint worker_id) {
4996 // The first nmethods is claimed by the first worker.
4997 if (worker_id == 0 && _first_nmethod != NULL) {
4998 clean_nmethod(_first_nmethod);
4999 _first_nmethod = NULL;
5000 }
5001
5002 int num_claimed_nmethods;
5003 nmethod* claimed_nmethods[MaxClaimNmethods];
5004
5005 while (true) {
5006 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5007
5008 if (num_claimed_nmethods == 0) {
5009 break;
5010 }
5011
5012 for (int i = 0; i < num_claimed_nmethods; i++) {
5013 clean_nmethod(claimed_nmethods[i]);
5014 }
5015 }
5016
5017 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
5018 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
5019 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
5020 }
5021
5022 void work_second_pass(uint worker_id) {
5023 nmethod* nm;
5024 // Take care of postponed nmethods.
5025 while ((nm = claim_postponed_nmethod()) != NULL) {
5026 clean_nmethod_postponed(nm);
5027 }
5028 }
5029 };
5030
5031 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5032
5033 class G1KlassCleaningTask : public StackObj {
5034 BoolObjectClosure* _is_alive;
5035 volatile jint _clean_klass_tree_claimed;
5036 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5037
5038 public:
5039 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5040 _is_alive(is_alive),
5041 _clean_klass_tree_claimed(0),
5042 _klass_iterator() {
5043 }
5044
5045 private:
5046 bool claim_clean_klass_tree_task() {
5047 if (_clean_klass_tree_claimed) {
5048 return false;
5049 }
5050
5051 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5052 }
5053
5054 InstanceKlass* claim_next_klass() {
5055 Klass* klass;
5056 do {
5057 klass =_klass_iterator.next_klass();
5058 } while (klass != NULL && !klass->oop_is_instance());
5059
5060 return (InstanceKlass*)klass;
5061 }
5062
5063 public:
5064
5065 void clean_klass(InstanceKlass* ik) {
5066 ik->clean_implementors_list(_is_alive);
5067 ik->clean_method_data(_is_alive);
5068
5069 // G1 specific cleanup work that has
5070 // been moved here to be done in parallel.
5071 ik->clean_dependent_nmethods();
5072 if (JvmtiExport::has_redefined_a_class()) {
5073 InstanceKlass::purge_previous_versions(ik);
5074 }
5075 }
5076
5077 void work() {
5078 ResourceMark rm;
5079
5080 // One worker will clean the subklass/sibling klass tree.
5081 if (claim_clean_klass_tree_task()) {
5082 Klass::clean_subklass_tree(_is_alive);
5083 }
5084
5085 // All workers will help cleaning the classes,
5086 InstanceKlass* klass;
5087 while ((klass = claim_next_klass()) != NULL) {
5088 clean_klass(klass);
5089 }
5090 }
5091 };
5092
5093 // To minimize the remark pause times, the tasks below are done in parallel.
5094 class G1ParallelCleaningTask : public AbstractGangTask {
5095 private:
5096 G1StringSymbolTableUnlinkTask _string_symbol_task;
5097 G1CodeCacheUnloadingTask _code_cache_task;
5098 G1KlassCleaningTask _klass_cleaning_task;
5099
5100 public:
5101 // The constructor is run in the VMThread.
5102 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5103 AbstractGangTask("Parallel Cleaning"),
5104 _string_symbol_task(is_alive, process_strings, process_symbols),
5105 _code_cache_task(num_workers, is_alive, unloading_occurred),
5106 _klass_cleaning_task(is_alive) {
5107 }
5108
5109 void pre_work_verification() {
5110 // The VM Thread will have registered Metadata during the single-threaded phase of MetadataStackOnMark.
5111 assert(Thread::current()->is_VM_thread()
5112 || !MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5113 }
5114
5115 void post_work_verification() {
5116 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5117 }
5118
5119 // The parallel work done by all worker threads.
5120 void work(uint worker_id) {
5121 pre_work_verification();
5122
5123 // Do first pass of code cache cleaning.
5124 _code_cache_task.work_first_pass(worker_id);
5125
5126 // Let the threads mark that the first pass is done.
5127 _code_cache_task.barrier_mark(worker_id);
5128
5129 // Clean the Strings and Symbols.
5130 _string_symbol_task.work(worker_id);
5131
5132 // Wait for all workers to finish the first code cache cleaning pass.
5133 _code_cache_task.barrier_wait(worker_id);
5134
5135 // Do the second code cache cleaning work, which realize on
5136 // the liveness information gathered during the first pass.
5137 _code_cache_task.work_second_pass(worker_id);
5138
5139 // Clean all klasses that were not unloaded.
5140 _klass_cleaning_task.work();
5141
5142 post_work_verification();
5143 }
5144 };
5145
5146
5147 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5148 bool process_strings,
5149 bool process_symbols,
5150 bool class_unloading_occurred) {
5151 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5152 workers()->active_workers() : 1);
5153
5154 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5155 n_workers, class_unloading_occurred);
5156 if (G1CollectedHeap::use_parallel_gc_threads()) {
5157 set_par_threads(n_workers);
5158 workers()->run_task(&g1_unlink_task);
5159 set_par_threads(0);
5160 } else {
5161 g1_unlink_task.work(0);
5162 }
5163 }
5164
5165 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5166 bool process_strings, bool process_symbols) {
5167 {
5168 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5169 _g1h->workers()->active_workers() : 1);
5170 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5171 if (G1CollectedHeap::use_parallel_gc_threads()) {
5172 set_par_threads(n_workers);
5173 workers()->run_task(&g1_unlink_task);
5174 set_par_threads(0);
5175 } else {
5176 g1_unlink_task.work(0);
5177 }
5178 }
5179
5180 if (G1StringDedup::is_enabled()) {
5181 G1StringDedup::unlink(is_alive);
5182 }
5183 }
5184
5185 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5186 private:
5187 DirtyCardQueueSet* _queue;
5188 public:
5189 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5190
5191 virtual void work(uint worker_id) {
5192 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5193 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5194
5195 RedirtyLoggedCardTableEntryClosure cl;
5196 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5197 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5198 } else {
5199 _queue->apply_closure_to_all_completed_buffers(&cl);
5200 }
5201
5202 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5203 }
5204 };
5205
5206 void G1CollectedHeap::redirty_logged_cards() {
5207 double redirty_logged_cards_start = os::elapsedTime();
5208
5209 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5210 _g1h->workers()->active_workers() : 1);
5211
5212 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5213 dirty_card_queue_set().reset_for_par_iteration();
5214 if (use_parallel_gc_threads()) {
5215 set_par_threads(n_workers);
5216 workers()->run_task(&redirty_task);
5217 set_par_threads(0);
5218 } else {
5219 redirty_task.work(0);
5220 }
5221
5222 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5223 dcq.merge_bufferlists(&dirty_card_queue_set());
5224 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5225
5226 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5227 }
5228
5229 // Weak Reference Processing support
5230
5231 // An always "is_alive" closure that is used to preserve referents.
5232 // If the object is non-null then it's alive. Used in the preservation
5233 // of referent objects that are pointed to by reference objects
5234 // discovered by the CM ref processor.
5235 class G1AlwaysAliveClosure: public BoolObjectClosure {
5236 G1CollectedHeap* _g1;
5237 public:
5238 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5239 bool do_object_b(oop p) {
5240 if (p != NULL) {
5241 return true;
5242 }
5243 return false;
5244 }
5245 };
5246
5247 bool G1STWIsAliveClosure::do_object_b(oop p) {
5248 // An object is reachable if it is outside the collection set,
5249 // or is inside and copied.
5250 return !_g1->obj_in_cs(p) || p->is_forwarded();
5251 }
5252
5253 // Non Copying Keep Alive closure
5254 class G1KeepAliveClosure: public OopClosure {
5255 G1CollectedHeap* _g1;
5256 public:
5257 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5258 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5259 void do_oop(oop* p) {
5260 oop obj = *p;
5261 assert(obj != NULL, "the caller should have filtered out NULL values");
5262
5263 const InCSetState cset_state = _g1->in_cset_state(obj);
5264 if (!cset_state.is_in_cset_or_humongous()) {
5265 return;
5266 }
5267 if (cset_state.is_in_cset()) {
5268 assert( obj->is_forwarded(), "invariant" );
5269 *p = obj->forwardee();
5270 } else {
5271 assert(!obj->is_forwarded(), "invariant" );
5272 assert(cset_state.is_humongous(),
5273 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5274 _g1->set_humongous_is_live(obj);
5275 }
5276 }
5277 };
5278
5279 // Copying Keep Alive closure - can be called from both
5280 // serial and parallel code as long as different worker
5281 // threads utilize different G1ParScanThreadState instances
5282 // and different queues.
5283
5284 class G1CopyingKeepAliveClosure: public OopClosure {
5285 G1CollectedHeap* _g1h;
5286 OopClosure* _copy_non_heap_obj_cl;
5287 G1ParScanThreadState* _par_scan_state;
5288
5289 public:
5290 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5291 OopClosure* non_heap_obj_cl,
5292 G1ParScanThreadState* pss):
5293 _g1h(g1h),
5294 _copy_non_heap_obj_cl(non_heap_obj_cl),
5295 _par_scan_state(pss)
5296 {}
5297
5298 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5299 virtual void do_oop( oop* p) { do_oop_work(p); }
5300
5301 template <class T> void do_oop_work(T* p) {
5302 oop obj = oopDesc::load_decode_heap_oop(p);
5303
5304 if (_g1h->is_in_cset_or_humongous(obj)) {
5305 // If the referent object has been forwarded (either copied
5306 // to a new location or to itself in the event of an
5307 // evacuation failure) then we need to update the reference
5308 // field and, if both reference and referent are in the G1
5309 // heap, update the RSet for the referent.
5310 //
5311 // If the referent has not been forwarded then we have to keep
5312 // it alive by policy. Therefore we have copy the referent.
5313 //
5314 // If the reference field is in the G1 heap then we can push
5315 // on the PSS queue. When the queue is drained (after each
5316 // phase of reference processing) the object and it's followers
5317 // will be copied, the reference field set to point to the
5318 // new location, and the RSet updated. Otherwise we need to
5319 // use the the non-heap or metadata closures directly to copy
5320 // the referent object and update the pointer, while avoiding
5321 // updating the RSet.
5322
5323 if (_g1h->is_in_g1_reserved(p)) {
5324 _par_scan_state->push_on_queue(p);
5325 } else {
5326 assert(!Metaspace::contains((const void*)p),
5327 err_msg("Unexpectedly found a pointer from metadata: "
5328 PTR_FORMAT, p));
5329 _copy_non_heap_obj_cl->do_oop(p);
5330 }
5331 }
5332 }
5333 };
5334
5335 // Serial drain queue closure. Called as the 'complete_gc'
5336 // closure for each discovered list in some of the
5337 // reference processing phases.
5338
5339 class G1STWDrainQueueClosure: public VoidClosure {
5340 protected:
5341 G1CollectedHeap* _g1h;
5342 G1ParScanThreadState* _par_scan_state;
5343
5344 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5345
5346 public:
5347 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5348 _g1h(g1h),
5349 _par_scan_state(pss)
5350 { }
5351
5352 void do_void() {
5353 G1ParScanThreadState* const pss = par_scan_state();
5354 pss->trim_queue();
5355 }
5356 };
5357
5358 // Parallel Reference Processing closures
5359
5360 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5361 // processing during G1 evacuation pauses.
5362
5363 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5364 private:
5365 G1CollectedHeap* _g1h;
5366 RefToScanQueueSet* _queues;
5367 FlexibleWorkGang* _workers;
5368 int _active_workers;
5369
5370 public:
5371 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5372 FlexibleWorkGang* workers,
5373 RefToScanQueueSet *task_queues,
5374 int n_workers) :
5375 _g1h(g1h),
5376 _queues(task_queues),
5377 _workers(workers),
5378 _active_workers(n_workers)
5379 {
5380 assert(n_workers > 0, "shouldn't call this otherwise");
5381 }
5382
5383 // Executes the given task using concurrent marking worker threads.
5384 virtual void execute(ProcessTask& task);
5385 virtual void execute(EnqueueTask& task);
5386 };
5387
5388 // Gang task for possibly parallel reference processing
5389
5390 class G1STWRefProcTaskProxy: public AbstractGangTask {
5391 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5392 ProcessTask& _proc_task;
5393 G1CollectedHeap* _g1h;
5394 RefToScanQueueSet *_task_queues;
5395 ParallelTaskTerminator* _terminator;
5396
5397 public:
5398 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5399 G1CollectedHeap* g1h,
5400 RefToScanQueueSet *task_queues,
5401 ParallelTaskTerminator* terminator) :
5402 AbstractGangTask("Process reference objects in parallel"),
5403 _proc_task(proc_task),
5404 _g1h(g1h),
5405 _task_queues(task_queues),
5406 _terminator(terminator)
5407 {}
5408
5409 virtual void work(uint worker_id) {
5410 // The reference processing task executed by a single worker.
5411 ResourceMark rm;
5412 HandleMark hm;
5413
5414 G1STWIsAliveClosure is_alive(_g1h);
5415
5416 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5417 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5418
5419 pss.set_evac_failure_closure(&evac_failure_cl);
5420
5421 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5422
5423 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5424
5425 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5426
5427 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5428 // We also need to mark copied objects.
5429 copy_non_heap_cl = ©_mark_non_heap_cl;
5430 }
5431
5432 // Keep alive closure.
5433 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5434
5435 // Complete GC closure
5436 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5437
5438 // Call the reference processing task's work routine.
5439 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5440
5441 // Note we cannot assert that the refs array is empty here as not all
5442 // of the processing tasks (specifically phase2 - pp2_work) execute
5443 // the complete_gc closure (which ordinarily would drain the queue) so
5444 // the queue may not be empty.
5445 }
5446 };
5447
5448 // Driver routine for parallel reference processing.
5449 // Creates an instance of the ref processing gang
5450 // task and has the worker threads execute it.
5451 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5452 assert(_workers != NULL, "Need parallel worker threads.");
5453
5454 ParallelTaskTerminator terminator(_active_workers, _queues);
5455 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5456
5457 _g1h->set_par_threads(_active_workers);
5458 _workers->run_task(&proc_task_proxy);
5459 _g1h->set_par_threads(0);
5460 }
5461
5462 // Gang task for parallel reference enqueueing.
5463
5464 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5465 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5466 EnqueueTask& _enq_task;
5467
5468 public:
5469 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5470 AbstractGangTask("Enqueue reference objects in parallel"),
5471 _enq_task(enq_task)
5472 { }
5473
5474 virtual void work(uint worker_id) {
5475 _enq_task.work(worker_id);
5476 }
5477 };
5478
5479 // Driver routine for parallel reference enqueueing.
5480 // Creates an instance of the ref enqueueing gang
5481 // task and has the worker threads execute it.
5482
5483 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5484 assert(_workers != NULL, "Need parallel worker threads.");
5485
5486 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5487
5488 _g1h->set_par_threads(_active_workers);
5489 _workers->run_task(&enq_task_proxy);
5490 _g1h->set_par_threads(0);
5491 }
5492
5493 // End of weak reference support closures
5494
5495 // Abstract task used to preserve (i.e. copy) any referent objects
5496 // that are in the collection set and are pointed to by reference
5497 // objects discovered by the CM ref processor.
5498
5499 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5500 protected:
5501 G1CollectedHeap* _g1h;
5502 RefToScanQueueSet *_queues;
5503 ParallelTaskTerminator _terminator;
5504 uint _n_workers;
5505
5506 public:
5507 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5508 AbstractGangTask("ParPreserveCMReferents"),
5509 _g1h(g1h),
5510 _queues(task_queues),
5511 _terminator(workers, _queues),
5512 _n_workers(workers)
5513 { }
5514
5515 void work(uint worker_id) {
5516 ResourceMark rm;
5517 HandleMark hm;
5518
5519 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5520 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5521
5522 pss.set_evac_failure_closure(&evac_failure_cl);
5523
5524 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5525
5526 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5527
5528 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5529
5530 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5531
5532 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5533 // We also need to mark copied objects.
5534 copy_non_heap_cl = ©_mark_non_heap_cl;
5535 }
5536
5537 // Is alive closure
5538 G1AlwaysAliveClosure always_alive(_g1h);
5539
5540 // Copying keep alive closure. Applied to referent objects that need
5541 // to be copied.
5542 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5543
5544 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5545
5546 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5547 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5548
5549 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5550 // So this must be true - but assert just in case someone decides to
5551 // change the worker ids.
5552 assert(0 <= worker_id && worker_id < limit, "sanity");
5553 assert(!rp->discovery_is_atomic(), "check this code");
5554
5555 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5556 for (uint idx = worker_id; idx < limit; idx += stride) {
5557 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5558
5559 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5560 while (iter.has_next()) {
5561 // Since discovery is not atomic for the CM ref processor, we
5562 // can see some null referent objects.
5563 iter.load_ptrs(DEBUG_ONLY(true));
5564 oop ref = iter.obj();
5565
5566 // This will filter nulls.
5567 if (iter.is_referent_alive()) {
5568 iter.make_referent_alive();
5569 }
5570 iter.move_to_next();
5571 }
5572 }
5573
5574 // Drain the queue - which may cause stealing
5575 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5576 drain_queue.do_void();
5577 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5578 assert(pss.queue_is_empty(), "should be");
5579 }
5580 };
5581
5582 // Weak Reference processing during an evacuation pause (part 1).
5583 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5584 double ref_proc_start = os::elapsedTime();
5585
5586 ReferenceProcessor* rp = _ref_processor_stw;
5587 assert(rp->discovery_enabled(), "should have been enabled");
5588
5589 // Any reference objects, in the collection set, that were 'discovered'
5590 // by the CM ref processor should have already been copied (either by
5591 // applying the external root copy closure to the discovered lists, or
5592 // by following an RSet entry).
5593 //
5594 // But some of the referents, that are in the collection set, that these
5595 // reference objects point to may not have been copied: the STW ref
5596 // processor would have seen that the reference object had already
5597 // been 'discovered' and would have skipped discovering the reference,
5598 // but would not have treated the reference object as a regular oop.
5599 // As a result the copy closure would not have been applied to the
5600 // referent object.
5601 //
5602 // We need to explicitly copy these referent objects - the references
5603 // will be processed at the end of remarking.
5604 //
5605 // We also need to do this copying before we process the reference
5606 // objects discovered by the STW ref processor in case one of these
5607 // referents points to another object which is also referenced by an
5608 // object discovered by the STW ref processor.
5609
5610 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5611 no_of_gc_workers == workers()->active_workers(),
5612 "Need to reset active GC workers");
5613
5614 set_par_threads(no_of_gc_workers);
5615 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5616 no_of_gc_workers,
5617 _task_queues);
5618
5619 if (G1CollectedHeap::use_parallel_gc_threads()) {
5620 workers()->run_task(&keep_cm_referents);
5621 } else {
5622 keep_cm_referents.work(0);
5623 }
5624
5625 set_par_threads(0);
5626
5627 // Closure to test whether a referent is alive.
5628 G1STWIsAliveClosure is_alive(this);
5629
5630 // Even when parallel reference processing is enabled, the processing
5631 // of JNI refs is serial and performed serially by the current thread
5632 // rather than by a worker. The following PSS will be used for processing
5633 // JNI refs.
5634
5635 // Use only a single queue for this PSS.
5636 G1ParScanThreadState pss(this, 0, NULL);
5637
5638 // We do not embed a reference processor in the copying/scanning
5639 // closures while we're actually processing the discovered
5640 // reference objects.
5641 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5642
5643 pss.set_evac_failure_closure(&evac_failure_cl);
5644
5645 assert(pss.queue_is_empty(), "pre-condition");
5646
5647 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5648
5649 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5650
5651 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5652
5653 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5654 // We also need to mark copied objects.
5655 copy_non_heap_cl = ©_mark_non_heap_cl;
5656 }
5657
5658 // Keep alive closure.
5659 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5660
5661 // Serial Complete GC closure
5662 G1STWDrainQueueClosure drain_queue(this, &pss);
5663
5664 // Setup the soft refs policy...
5665 rp->setup_policy(false);
5666
5667 ReferenceProcessorStats stats;
5668 if (!rp->processing_is_mt()) {
5669 // Serial reference processing...
5670 stats = rp->process_discovered_references(&is_alive,
5671 &keep_alive,
5672 &drain_queue,
5673 NULL,
5674 _gc_timer_stw,
5675 _gc_tracer_stw->gc_id());
5676 } else {
5677 // Parallel reference processing
5678 assert(rp->num_q() == no_of_gc_workers, "sanity");
5679 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5680
5681 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5682 stats = rp->process_discovered_references(&is_alive,
5683 &keep_alive,
5684 &drain_queue,
5685 &par_task_executor,
5686 _gc_timer_stw,
5687 _gc_tracer_stw->gc_id());
5688 }
5689
5690 _gc_tracer_stw->report_gc_reference_stats(stats);
5691
5692 // We have completed copying any necessary live referent objects.
5693 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5694
5695 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5696 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5697 }
5698
5699 // Weak Reference processing during an evacuation pause (part 2).
5700 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5701 double ref_enq_start = os::elapsedTime();
5702
5703 ReferenceProcessor* rp = _ref_processor_stw;
5704 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5705
5706 // Now enqueue any remaining on the discovered lists on to
5707 // the pending list.
5708 if (!rp->processing_is_mt()) {
5709 // Serial reference processing...
5710 rp->enqueue_discovered_references();
5711 } else {
5712 // Parallel reference enqueueing
5713
5714 assert(no_of_gc_workers == workers()->active_workers(),
5715 "Need to reset active workers");
5716 assert(rp->num_q() == no_of_gc_workers, "sanity");
5717 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5718
5719 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5720 rp->enqueue_discovered_references(&par_task_executor);
5721 }
5722
5723 rp->verify_no_references_recorded();
5724 assert(!rp->discovery_enabled(), "should have been disabled");
5725
5726 // FIXME
5727 // CM's reference processing also cleans up the string and symbol tables.
5728 // Should we do that here also? We could, but it is a serial operation
5729 // and could significantly increase the pause time.
5730
5731 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5732 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5733 }
5734
5735 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5736 _expand_heap_after_alloc_failure = true;
5737 _evacuation_failed = false;
5738
5739 // Should G1EvacuationFailureALot be in effect for this GC?
5740 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5741
5742 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5743
5744 // Disable the hot card cache.
5745 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5746 hot_card_cache->reset_hot_cache_claimed_index();
5747 hot_card_cache->set_use_cache(false);
5748
5749 uint n_workers;
5750 if (G1CollectedHeap::use_parallel_gc_threads()) {
5751 n_workers =
5752 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5753 workers()->active_workers(),
5754 Threads::number_of_non_daemon_threads());
5755 assert(UseDynamicNumberOfGCThreads ||
5756 n_workers == workers()->total_workers(),
5757 "If not dynamic should be using all the workers");
5758 workers()->set_active_workers(n_workers);
5759 set_par_threads(n_workers);
5760 } else {
5761 assert(n_par_threads() == 0,
5762 "Should be the original non-parallel value");
5763 n_workers = 1;
5764 }
5765
5766
5767 init_for_evac_failure(NULL);
5768
5769 rem_set()->prepare_for_younger_refs_iterate(true);
5770
5771 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5772 double start_par_time_sec = os::elapsedTime();
5773 double end_par_time_sec;
5774
5775 {
5776 G1RootProcessor root_processor(this);
5777 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5778 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5779 if (g1_policy()->during_initial_mark_pause()) {
5780 ClassLoaderDataGraph::clear_claimed_marks();
5781 }
5782
5783 if (G1CollectedHeap::use_parallel_gc_threads()) {
5784 // The individual threads will set their evac-failure closures.
5785 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5786 // These tasks use ShareHeap::_process_strong_tasks
5787 assert(UseDynamicNumberOfGCThreads ||
5788 workers()->active_workers() == workers()->total_workers(),
5789 "If not dynamic should be using all the workers");
5790 workers()->run_task(&g1_par_task);
5791 } else {
5792 g1_par_task.set_for_termination(n_workers);
5793 g1_par_task.work(0);
5794 }
5795 end_par_time_sec = os::elapsedTime();
5796
5797 // Closing the inner scope will execute the destructor
5798 // for the G1RootProcessor object. We record the current
5799 // elapsed time before closing the scope so that time
5800 // taken for the destructor is NOT included in the
5801 // reported parallel time.
5802 }
5803
5804 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5805
5806 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5807 phase_times->record_par_time(par_time_ms);
5808
5809 double code_root_fixup_time_ms =
5810 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5811 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5812
5813 set_par_threads(0);
5814
5815 // Process any discovered reference objects - we have
5816 // to do this _before_ we retire the GC alloc regions
5817 // as we may have to copy some 'reachable' referent
5818 // objects (and their reachable sub-graphs) that were
5819 // not copied during the pause.
5820 process_discovered_references(n_workers);
5821
5822 if (G1StringDedup::is_enabled()) {
5823 double fixup_start = os::elapsedTime();
5824
5825 G1STWIsAliveClosure is_alive(this);
5826 G1KeepAliveClosure keep_alive(this);
5827 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5828
5829 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5830 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5831 }
5832
5833 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5834 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5835
5836 // Reset and re-enable the hot card cache.
5837 // Note the counts for the cards in the regions in the
5838 // collection set are reset when the collection set is freed.
5839 hot_card_cache->reset_hot_cache();
5840 hot_card_cache->set_use_cache(true);
5841
5842 purge_code_root_memory();
5843
5844 if (g1_policy()->during_initial_mark_pause()) {
5845 // Reset the claim values set during marking the strong code roots
5846 reset_heap_region_claim_values();
5847 }
5848
5849 finalize_for_evac_failure();
5850
5851 if (evacuation_failed()) {
5852 remove_self_forwarding_pointers();
5853
5854 // Reset the G1EvacuationFailureALot counters and flags
5855 // Note: the values are reset only when an actual
5856 // evacuation failure occurs.
5857 NOT_PRODUCT(reset_evacuation_should_fail();)
5858 }
5859
5860 // Enqueue any remaining references remaining on the STW
5861 // reference processor's discovered lists. We need to do
5862 // this after the card table is cleaned (and verified) as
5863 // the act of enqueueing entries on to the pending list
5864 // will log these updates (and dirty their associated
5865 // cards). We need these updates logged to update any
5866 // RSets.
5867 enqueue_discovered_references(n_workers);
5868
5869 redirty_logged_cards();
5870 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5871 }
5872
5873 void G1CollectedHeap::free_region(HeapRegion* hr,
5874 FreeRegionList* free_list,
5875 bool par,
5876 bool locked) {
5877 assert(!hr->is_free(), "the region should not be free");
5878 assert(!hr->is_empty(), "the region should not be empty");
5879 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5880 assert(free_list != NULL, "pre-condition");
5881
5882 if (G1VerifyBitmaps) {
5883 MemRegion mr(hr->bottom(), hr->end());
5884 concurrent_mark()->clearRangePrevBitmap(mr);
5885 }
5886
5887 // Clear the card counts for this region.
5888 // Note: we only need to do this if the region is not young
5889 // (since we don't refine cards in young regions).
5890 if (!hr->is_young()) {
5891 _cg1r->hot_card_cache()->reset_card_counts(hr);
5892 }
5893 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5894 free_list->add_ordered(hr);
5895 }
5896
5897 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5898 FreeRegionList* free_list,
5899 bool par) {
5900 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5901 assert(free_list != NULL, "pre-condition");
5902
5903 size_t hr_capacity = hr->capacity();
5904 // We need to read this before we make the region non-humongous,
5905 // otherwise the information will be gone.
5906 uint last_index = hr->last_hc_index();
5907 hr->clear_humongous();
5908 free_region(hr, free_list, par);
5909
5910 uint i = hr->hrm_index() + 1;
5911 while (i < last_index) {
5912 HeapRegion* curr_hr = region_at(i);
5913 assert(curr_hr->continuesHumongous(), "invariant");
5914 curr_hr->clear_humongous();
5915 free_region(curr_hr, free_list, par);
5916 i += 1;
5917 }
5918 }
5919
5920 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5921 const HeapRegionSetCount& humongous_regions_removed) {
5922 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5923 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5924 _old_set.bulk_remove(old_regions_removed);
5925 _humongous_set.bulk_remove(humongous_regions_removed);
5926 }
5927
5928 }
5929
5930 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5931 assert(list != NULL, "list can't be null");
5932 if (!list->is_empty()) {
5933 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5934 _hrm.insert_list_into_free_list(list);
5935 }
5936 }
5937
5938 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5939 _allocator->decrease_used(bytes);
5940 }
5941
5942 class G1ParCleanupCTTask : public AbstractGangTask {
5943 G1SATBCardTableModRefBS* _ct_bs;
5944 G1CollectedHeap* _g1h;
5945 HeapRegion* volatile _su_head;
5946 public:
5947 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5948 G1CollectedHeap* g1h) :
5949 AbstractGangTask("G1 Par Cleanup CT Task"),
5950 _ct_bs(ct_bs), _g1h(g1h) { }
5951
5952 void work(uint worker_id) {
5953 HeapRegion* r;
5954 while (r = _g1h->pop_dirty_cards_region()) {
5955 clear_cards(r);
5956 }
5957 }
5958
5959 void clear_cards(HeapRegion* r) {
5960 // Cards of the survivors should have already been dirtied.
5961 if (!r->is_survivor()) {
5962 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5963 }
5964 }
5965 };
5966
5967 #ifndef PRODUCT
5968 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5969 G1CollectedHeap* _g1h;
5970 G1SATBCardTableModRefBS* _ct_bs;
5971 public:
5972 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5973 : _g1h(g1h), _ct_bs(ct_bs) { }
5974 virtual bool doHeapRegion(HeapRegion* r) {
5975 if (r->is_survivor()) {
5976 _g1h->verify_dirty_region(r);
5977 } else {
5978 _g1h->verify_not_dirty_region(r);
5979 }
5980 return false;
5981 }
5982 };
5983
5984 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5985 // All of the region should be clean.
5986 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5987 MemRegion mr(hr->bottom(), hr->end());
5988 ct_bs->verify_not_dirty_region(mr);
5989 }
5990
5991 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5992 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5993 // dirty allocated blocks as they allocate them. The thread that
5994 // retires each region and replaces it with a new one will do a
5995 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5996 // not dirty that area (one less thing to have to do while holding
5997 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5998 // is dirty.
5999 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6000 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6001 if (hr->is_young()) {
6002 ct_bs->verify_g1_young_region(mr);
6003 } else {
6004 ct_bs->verify_dirty_region(mr);
6005 }
6006 }
6007
6008 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6009 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6010 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6011 verify_dirty_region(hr);
6012 }
6013 }
6014
6015 void G1CollectedHeap::verify_dirty_young_regions() {
6016 verify_dirty_young_list(_young_list->first_region());
6017 }
6018
6019 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6020 HeapWord* tams, HeapWord* end) {
6021 guarantee(tams <= end,
6022 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6023 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6024 if (result < end) {
6025 gclog_or_tty->cr();
6026 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6027 bitmap_name, result);
6028 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6029 bitmap_name, tams, end);
6030 return false;
6031 }
6032 return true;
6033 }
6034
6035 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6036 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6037 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6038
6039 HeapWord* bottom = hr->bottom();
6040 HeapWord* ptams = hr->prev_top_at_mark_start();
6041 HeapWord* ntams = hr->next_top_at_mark_start();
6042 HeapWord* end = hr->end();
6043
6044 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6045
6046 bool res_n = true;
6047 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6048 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6049 // if we happen to be in that state.
6050 if (mark_in_progress() || !_cmThread->in_progress()) {
6051 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6052 }
6053 if (!res_p || !res_n) {
6054 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6055 HR_FORMAT_PARAMS(hr));
6056 gclog_or_tty->print_cr("#### Caller: %s", caller);
6057 return false;
6058 }
6059 return true;
6060 }
6061
6062 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6063 if (!G1VerifyBitmaps) return;
6064
6065 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6066 }
6067
6068 class G1VerifyBitmapClosure : public HeapRegionClosure {
6069 private:
6070 const char* _caller;
6071 G1CollectedHeap* _g1h;
6072 bool _failures;
6073
6074 public:
6075 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6076 _caller(caller), _g1h(g1h), _failures(false) { }
6077
6078 bool failures() { return _failures; }
6079
6080 virtual bool doHeapRegion(HeapRegion* hr) {
6081 if (hr->continuesHumongous()) return false;
6082
6083 bool result = _g1h->verify_bitmaps(_caller, hr);
6084 if (!result) {
6085 _failures = true;
6086 }
6087 return false;
6088 }
6089 };
6090
6091 void G1CollectedHeap::check_bitmaps(const char* caller) {
6092 if (!G1VerifyBitmaps) return;
6093
6094 G1VerifyBitmapClosure cl(caller, this);
6095 heap_region_iterate(&cl);
6096 guarantee(!cl.failures(), "bitmap verification");
6097 }
6098
6099 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
6100 private:
6101 bool _failures;
6102 public:
6103 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
6104
6105 virtual bool doHeapRegion(HeapRegion* hr) {
6106 uint i = hr->hrm_index();
6107 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
6108 if (hr->isHumongous()) {
6109 if (hr->in_collection_set()) {
6110 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
6111 _failures = true;
6112 return true;
6113 }
6114 if (cset_state.is_in_cset()) {
6115 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
6116 _failures = true;
6117 return true;
6118 }
6119 if (hr->continuesHumongous() && cset_state.is_humongous()) {
6120 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
6121 _failures = true;
6122 return true;
6123 }
6124 } else {
6125 if (cset_state.is_humongous()) {
6126 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
6127 _failures = true;
6128 return true;
6129 }
6130 if (hr->in_collection_set() != cset_state.is_in_cset()) {
6131 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6132 hr->in_collection_set(), cset_state.value(), i);
6133 _failures = true;
6134 return true;
6135 }
6136 if (cset_state.is_in_cset()) {
6137 if (hr->is_young() != (cset_state.is_young())) {
6138 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6139 hr->is_young(), cset_state.value(), i);
6140 _failures = true;
6141 return true;
6142 }
6143 if (hr->is_old() != (cset_state.is_old())) {
6144 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6145 hr->is_old(), cset_state.value(), i);
6146 _failures = true;
6147 return true;
6148 }
6149 }
6150 }
6151 return false;
6152 }
6153
6154 bool failures() const { return _failures; }
6155 };
6156
6157 bool G1CollectedHeap::check_cset_fast_test() {
6158 G1CheckCSetFastTableClosure cl;
6159 _hrm.iterate(&cl);
6160 return !cl.failures();
6161 }
6162 #endif // PRODUCT
6163
6164 void G1CollectedHeap::cleanUpCardTable() {
6165 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6166 double start = os::elapsedTime();
6167
6168 {
6169 // Iterate over the dirty cards region list.
6170 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6171
6172 if (G1CollectedHeap::use_parallel_gc_threads()) {
6173 set_par_threads();
6174 workers()->run_task(&cleanup_task);
6175 set_par_threads(0);
6176 } else {
6177 while (_dirty_cards_region_list) {
6178 HeapRegion* r = _dirty_cards_region_list;
6179 cleanup_task.clear_cards(r);
6180 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6181 if (_dirty_cards_region_list == r) {
6182 // The last region.
6183 _dirty_cards_region_list = NULL;
6184 }
6185 r->set_next_dirty_cards_region(NULL);
6186 }
6187 }
6188 #ifndef PRODUCT
6189 if (G1VerifyCTCleanup || VerifyAfterGC) {
6190 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6191 heap_region_iterate(&cleanup_verifier);
6192 }
6193 #endif
6194 }
6195
6196 double elapsed = os::elapsedTime() - start;
6197 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6198 }
6199
6200 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6201 size_t pre_used = 0;
6202 FreeRegionList local_free_list("Local List for CSet Freeing");
6203
6204 double young_time_ms = 0.0;
6205 double non_young_time_ms = 0.0;
6206
6207 // Since the collection set is a superset of the the young list,
6208 // all we need to do to clear the young list is clear its
6209 // head and length, and unlink any young regions in the code below
6210 _young_list->clear();
6211
6212 G1CollectorPolicy* policy = g1_policy();
6213
6214 double start_sec = os::elapsedTime();
6215 bool non_young = true;
6216
6217 HeapRegion* cur = cs_head;
6218 int age_bound = -1;
6219 size_t rs_lengths = 0;
6220
6221 while (cur != NULL) {
6222 assert(!is_on_master_free_list(cur), "sanity");
6223 if (non_young) {
6224 if (cur->is_young()) {
6225 double end_sec = os::elapsedTime();
6226 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6227 non_young_time_ms += elapsed_ms;
6228
6229 start_sec = os::elapsedTime();
6230 non_young = false;
6231 }
6232 } else {
6233 if (!cur->is_young()) {
6234 double end_sec = os::elapsedTime();
6235 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6236 young_time_ms += elapsed_ms;
6237
6238 start_sec = os::elapsedTime();
6239 non_young = true;
6240 }
6241 }
6242
6243 rs_lengths += cur->rem_set()->occupied_locked();
6244
6245 HeapRegion* next = cur->next_in_collection_set();
6246 assert(cur->in_collection_set(), "bad CS");
6247 cur->set_next_in_collection_set(NULL);
6248 cur->set_in_collection_set(false);
6249
6250 if (cur->is_young()) {
6251 int index = cur->young_index_in_cset();
6252 assert(index != -1, "invariant");
6253 assert((uint) index < policy->young_cset_region_length(), "invariant");
6254 size_t words_survived = _surviving_young_words[index];
6255 cur->record_surv_words_in_group(words_survived);
6256
6257 // At this point the we have 'popped' cur from the collection set
6258 // (linked via next_in_collection_set()) but it is still in the
6259 // young list (linked via next_young_region()). Clear the
6260 // _next_young_region field.
6261 cur->set_next_young_region(NULL);
6262 } else {
6263 int index = cur->young_index_in_cset();
6264 assert(index == -1, "invariant");
6265 }
6266
6267 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6268 (!cur->is_young() && cur->young_index_in_cset() == -1),
6269 "invariant" );
6270
6271 if (!cur->evacuation_failed()) {
6272 MemRegion used_mr = cur->used_region();
6273
6274 // And the region is empty.
6275 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6276 pre_used += cur->used();
6277 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6278 } else {
6279 cur->uninstall_surv_rate_group();
6280 if (cur->is_young()) {
6281 cur->set_young_index_in_cset(-1);
6282 }
6283 cur->set_evacuation_failed(false);
6284 // The region is now considered to be old.
6285 cur->set_old();
6286 _old_set.add(cur);
6287 evacuation_info.increment_collectionset_used_after(cur->used());
6288 }
6289 cur = next;
6290 }
6291
6292 evacuation_info.set_regions_freed(local_free_list.length());
6293 policy->record_max_rs_lengths(rs_lengths);
6294 policy->cset_regions_freed();
6295
6296 double end_sec = os::elapsedTime();
6297 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6298
6299 if (non_young) {
6300 non_young_time_ms += elapsed_ms;
6301 } else {
6302 young_time_ms += elapsed_ms;
6303 }
6304
6305 prepend_to_freelist(&local_free_list);
6306 decrement_summary_bytes(pre_used);
6307 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6308 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6309 }
6310
6311 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6312 private:
6313 FreeRegionList* _free_region_list;
6314 HeapRegionSet* _proxy_set;
6315 HeapRegionSetCount _humongous_regions_removed;
6316 size_t _freed_bytes;
6317 public:
6318
6319 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6320 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6321 }
6322
6323 virtual bool doHeapRegion(HeapRegion* r) {
6324 if (!r->startsHumongous()) {
6325 return false;
6326 }
6327
6328 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6329
6330 oop obj = (oop)r->bottom();
6331 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6332
6333 // The following checks whether the humongous object is live are sufficient.
6334 // The main additional check (in addition to having a reference from the roots
6335 // or the young gen) is whether the humongous object has a remembered set entry.
6336 //
6337 // A humongous object cannot be live if there is no remembered set for it
6338 // because:
6339 // - there can be no references from within humongous starts regions referencing
6340 // the object because we never allocate other objects into them.
6341 // (I.e. there are no intra-region references that may be missed by the
6342 // remembered set)
6343 // - as soon there is a remembered set entry to the humongous starts region
6344 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6345 // until the end of a concurrent mark.
6346 //
6347 // It is not required to check whether the object has been found dead by marking
6348 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6349 // all objects allocated during that time are considered live.
6350 // SATB marking is even more conservative than the remembered set.
6351 // So if at this point in the collection there is no remembered set entry,
6352 // nobody has a reference to it.
6353 // At the start of collection we flush all refinement logs, and remembered sets
6354 // are completely up-to-date wrt to references to the humongous object.
6355 //
6356 // Other implementation considerations:
6357 // - never consider object arrays at this time because they would pose
6358 // considerable effort for cleaning up the the remembered sets. This is
6359 // required because stale remembered sets might reference locations that
6360 // are currently allocated into.
6361 uint region_idx = r->hrm_index();
6362 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6363 !r->rem_set()->is_empty()) {
6364
6365 if (G1TraceEagerReclaimHumongousObjects) {
6366 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6367 region_idx,
6368 obj->size()*HeapWordSize,
6369 r->bottom(),
6370 r->region_num(),
6371 r->rem_set()->occupied(),
6372 r->rem_set()->strong_code_roots_list_length(),
6373 next_bitmap->isMarked(r->bottom()),
6374 g1h->is_humongous_reclaim_candidate(region_idx),
6375 obj->is_typeArray()
6376 );
6377 }
6378
6379 return false;
6380 }
6381
6382 guarantee(obj->is_typeArray(),
6383 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6384 PTR_FORMAT " is not.",
6385 r->bottom()));
6386
6387 if (G1TraceEagerReclaimHumongousObjects) {
6388 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6389 region_idx,
6390 obj->size()*HeapWordSize,
6391 r->bottom(),
6392 r->region_num(),
6393 r->rem_set()->occupied(),
6394 r->rem_set()->strong_code_roots_list_length(),
6395 next_bitmap->isMarked(r->bottom()),
6396 g1h->is_humongous_reclaim_candidate(region_idx),
6397 obj->is_typeArray()
6398 );
6399 }
6400 // Need to clear mark bit of the humongous object if already set.
6401 if (next_bitmap->isMarked(r->bottom())) {
6402 next_bitmap->clear(r->bottom());
6403 }
6404 _freed_bytes += r->used();
6405 r->set_containing_set(NULL);
6406 _humongous_regions_removed.increment(1u, r->capacity());
6407 g1h->free_humongous_region(r, _free_region_list, false);
6408
6409 return false;
6410 }
6411
6412 HeapRegionSetCount& humongous_free_count() {
6413 return _humongous_regions_removed;
6414 }
6415
6416 size_t bytes_freed() const {
6417 return _freed_bytes;
6418 }
6419
6420 size_t humongous_reclaimed() const {
6421 return _humongous_regions_removed.length();
6422 }
6423 };
6424
6425 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6426 assert_at_safepoint(true);
6427
6428 if (!G1EagerReclaimHumongousObjects ||
6429 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6430 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6431 return;
6432 }
6433
6434 double start_time = os::elapsedTime();
6435
6436 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6437
6438 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6439 heap_region_iterate(&cl);
6440
6441 HeapRegionSetCount empty_set;
6442 remove_from_old_sets(empty_set, cl.humongous_free_count());
6443
6444 G1HRPrinter* hr_printer = _g1h->hr_printer();
6445 if (hr_printer->is_active()) {
6446 FreeRegionListIterator iter(&local_cleanup_list);
6447 while (iter.more_available()) {
6448 HeapRegion* hr = iter.get_next();
6449 hr_printer->cleanup(hr);
6450 }
6451 }
6452
6453 prepend_to_freelist(&local_cleanup_list);
6454 decrement_summary_bytes(cl.bytes_freed());
6455
6456 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6457 cl.humongous_reclaimed());
6458 }
6459
6460 // This routine is similar to the above but does not record
6461 // any policy statistics or update free lists; we are abandoning
6462 // the current incremental collection set in preparation of a
6463 // full collection. After the full GC we will start to build up
6464 // the incremental collection set again.
6465 // This is only called when we're doing a full collection
6466 // and is immediately followed by the tearing down of the young list.
6467
6468 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6469 HeapRegion* cur = cs_head;
6470
6471 while (cur != NULL) {
6472 HeapRegion* next = cur->next_in_collection_set();
6473 assert(cur->in_collection_set(), "bad CS");
6474 cur->set_next_in_collection_set(NULL);
6475 cur->set_in_collection_set(false);
6476 cur->set_young_index_in_cset(-1);
6477 cur = next;
6478 }
6479 }
6480
6481 void G1CollectedHeap::set_free_regions_coming() {
6482 if (G1ConcRegionFreeingVerbose) {
6483 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6484 "setting free regions coming");
6485 }
6486
6487 assert(!free_regions_coming(), "pre-condition");
6488 _free_regions_coming = true;
6489 }
6490
6491 void G1CollectedHeap::reset_free_regions_coming() {
6492 assert(free_regions_coming(), "pre-condition");
6493
6494 {
6495 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6496 _free_regions_coming = false;
6497 SecondaryFreeList_lock->notify_all();
6498 }
6499
6500 if (G1ConcRegionFreeingVerbose) {
6501 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6502 "reset free regions coming");
6503 }
6504 }
6505
6506 void G1CollectedHeap::wait_while_free_regions_coming() {
6507 // Most of the time we won't have to wait, so let's do a quick test
6508 // first before we take the lock.
6509 if (!free_regions_coming()) {
6510 return;
6511 }
6512
6513 if (G1ConcRegionFreeingVerbose) {
6514 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6515 "waiting for free regions");
6516 }
6517
6518 {
6519 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6520 while (free_regions_coming()) {
6521 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6522 }
6523 }
6524
6525 if (G1ConcRegionFreeingVerbose) {
6526 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6527 "done waiting for free regions");
6528 }
6529 }
6530
6531 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6532 assert(heap_lock_held_for_gc(),
6533 "the heap lock should already be held by or for this thread");
6534 _young_list->push_region(hr);
6535 }
6536
6537 class NoYoungRegionsClosure: public HeapRegionClosure {
6538 private:
6539 bool _success;
6540 public:
6541 NoYoungRegionsClosure() : _success(true) { }
6542 bool doHeapRegion(HeapRegion* r) {
6543 if (r->is_young()) {
6544 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6545 r->bottom(), r->end());
6546 _success = false;
6547 }
6548 return false;
6549 }
6550 bool success() { return _success; }
6551 };
6552
6553 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6554 bool ret = _young_list->check_list_empty(check_sample);
6555
6556 if (check_heap) {
6557 NoYoungRegionsClosure closure;
6558 heap_region_iterate(&closure);
6559 ret = ret && closure.success();
6560 }
6561
6562 return ret;
6563 }
6564
6565 class TearDownRegionSetsClosure : public HeapRegionClosure {
6566 private:
6567 HeapRegionSet *_old_set;
6568
6569 public:
6570 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6571
6572 bool doHeapRegion(HeapRegion* r) {
6573 if (r->is_old()) {
6574 _old_set->remove(r);
6575 } else {
6576 // We ignore free regions, we'll empty the free list afterwards.
6577 // We ignore young regions, we'll empty the young list afterwards.
6578 // We ignore humongous regions, we're not tearing down the
6579 // humongous regions set.
6580 assert(r->is_free() || r->is_young() || r->isHumongous(),
6581 "it cannot be another type");
6582 }
6583 return false;
6584 }
6585
6586 ~TearDownRegionSetsClosure() {
6587 assert(_old_set->is_empty(), "post-condition");
6588 }
6589 };
6590
6591 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6592 assert_at_safepoint(true /* should_be_vm_thread */);
6593
6594 if (!free_list_only) {
6595 TearDownRegionSetsClosure cl(&_old_set);
6596 heap_region_iterate(&cl);
6597
6598 // Note that emptying the _young_list is postponed and instead done as
6599 // the first step when rebuilding the regions sets again. The reason for
6600 // this is that during a full GC string deduplication needs to know if
6601 // a collected region was young or old when the full GC was initiated.
6602 }
6603 _hrm.remove_all_free_regions();
6604 }
6605
6606 class RebuildRegionSetsClosure : public HeapRegionClosure {
6607 private:
6608 bool _free_list_only;
6609 HeapRegionSet* _old_set;
6610 HeapRegionManager* _hrm;
6611 size_t _total_used;
6612
6613 public:
6614 RebuildRegionSetsClosure(bool free_list_only,
6615 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6616 _free_list_only(free_list_only),
6617 _old_set(old_set), _hrm(hrm), _total_used(0) {
6618 assert(_hrm->num_free_regions() == 0, "pre-condition");
6619 if (!free_list_only) {
6620 assert(_old_set->is_empty(), "pre-condition");
6621 }
6622 }
6623
6624 bool doHeapRegion(HeapRegion* r) {
6625 if (r->continuesHumongous()) {
6626 return false;
6627 }
6628
6629 if (r->is_empty()) {
6630 // Add free regions to the free list
6631 r->set_free();
6632 r->set_allocation_context(AllocationContext::system());
6633 _hrm->insert_into_free_list(r);
6634 } else if (!_free_list_only) {
6635 assert(!r->is_young(), "we should not come across young regions");
6636
6637 if (r->isHumongous()) {
6638 // We ignore humongous regions, we left the humongous set unchanged
6639 } else {
6640 // Objects that were compacted would have ended up on regions
6641 // that were previously old or free.
6642 assert(r->is_free() || r->is_old(), "invariant");
6643 // We now consider them old, so register as such.
6644 r->set_old();
6645 _old_set->add(r);
6646 }
6647 _total_used += r->used();
6648 }
6649
6650 return false;
6651 }
6652
6653 size_t total_used() {
6654 return _total_used;
6655 }
6656 };
6657
6658 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6659 assert_at_safepoint(true /* should_be_vm_thread */);
6660
6661 if (!free_list_only) {
6662 _young_list->empty_list();
6663 }
6664
6665 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6666 heap_region_iterate(&cl);
6667
6668 if (!free_list_only) {
6669 _allocator->set_used(cl.total_used());
6670 }
6671 assert(_allocator->used_unlocked() == recalculate_used(),
6672 err_msg("inconsistent _allocator->used_unlocked(), "
6673 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6674 _allocator->used_unlocked(), recalculate_used()));
6675 }
6676
6677 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6678 _refine_cte_cl->set_concurrent(concurrent);
6679 }
6680
6681 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6682 HeapRegion* hr = heap_region_containing(p);
6683 return hr->is_in(p);
6684 }
6685
6686 // Methods for the mutator alloc region
6687
6688 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6689 bool force) {
6690 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6691 assert(!force || g1_policy()->can_expand_young_list(),
6692 "if force is true we should be able to expand the young list");
6693 bool young_list_full = g1_policy()->is_young_list_full();
6694 if (force || !young_list_full) {
6695 HeapRegion* new_alloc_region = new_region(word_size,
6696 false /* is_old */,
6697 false /* do_expand */);
6698 if (new_alloc_region != NULL) {
6699 set_region_short_lived_locked(new_alloc_region);
6700 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6701 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6702 return new_alloc_region;
6703 }
6704 }
6705 return NULL;
6706 }
6707
6708 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6709 size_t allocated_bytes) {
6710 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6711 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6712
6713 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6714 _allocator->increase_used(allocated_bytes);
6715 _hr_printer.retire(alloc_region);
6716 // We update the eden sizes here, when the region is retired,
6717 // instead of when it's allocated, since this is the point that its
6718 // used space has been recored in _summary_bytes_used.
6719 g1mm()->update_eden_size();
6720 }
6721
6722 void G1CollectedHeap::set_par_threads() {
6723 // Don't change the number of workers. Use the value previously set
6724 // in the workgroup.
6725 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6726 uint n_workers = workers()->active_workers();
6727 assert(UseDynamicNumberOfGCThreads ||
6728 n_workers == workers()->total_workers(),
6729 "Otherwise should be using the total number of workers");
6730 if (n_workers == 0) {
6731 assert(false, "Should have been set in prior evacuation pause.");
6732 n_workers = ParallelGCThreads;
6733 workers()->set_active_workers(n_workers);
6734 }
6735 set_par_threads(n_workers);
6736 }
6737
6738 // Methods for the GC alloc regions
6739
6740 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6741 uint count,
6742 InCSetState dest) {
6743 assert(FreeList_lock->owned_by_self(), "pre-condition");
6744
6745 if (count < g1_policy()->max_regions(dest)) {
6746 const bool is_survivor = (dest.is_young());
6747 HeapRegion* new_alloc_region = new_region(word_size,
6748 !is_survivor,
6749 true /* do_expand */);
6750 if (new_alloc_region != NULL) {
6751 // We really only need to do this for old regions given that we
6752 // should never scan survivors. But it doesn't hurt to do it
6753 // for survivors too.
6754 new_alloc_region->record_timestamp();
6755 if (is_survivor) {
6756 new_alloc_region->set_survivor();
6757 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6758 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6759 } else {
6760 new_alloc_region->set_old();
6761 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6762 check_bitmaps("Old Region Allocation", new_alloc_region);
6763 }
6764 bool during_im = g1_policy()->during_initial_mark_pause();
6765 new_alloc_region->note_start_of_copying(during_im);
6766 return new_alloc_region;
6767 }
6768 }
6769 return NULL;
6770 }
6771
6772 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6773 size_t allocated_bytes,
6774 InCSetState dest) {
6775 bool during_im = g1_policy()->during_initial_mark_pause();
6776 alloc_region->note_end_of_copying(during_im);
6777 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6778 if (dest.is_young()) {
6779 young_list()->add_survivor_region(alloc_region);
6780 } else {
6781 _old_set.add(alloc_region);
6782 }
6783 _hr_printer.retire(alloc_region);
6784 }
6785
6786 // Heap region set verification
6787
6788 class VerifyRegionListsClosure : public HeapRegionClosure {
6789 private:
6790 HeapRegionSet* _old_set;
6791 HeapRegionSet* _humongous_set;
6792 HeapRegionManager* _hrm;
6793
6794 public:
6795 HeapRegionSetCount _old_count;
6796 HeapRegionSetCount _humongous_count;
6797 HeapRegionSetCount _free_count;
6798
6799 VerifyRegionListsClosure(HeapRegionSet* old_set,
6800 HeapRegionSet* humongous_set,
6801 HeapRegionManager* hrm) :
6802 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6803 _old_count(), _humongous_count(), _free_count(){ }
6804
6805 bool doHeapRegion(HeapRegion* hr) {
6806 if (hr->continuesHumongous()) {
6807 return false;
6808 }
6809
6810 if (hr->is_young()) {
6811 // TODO
6812 } else if (hr->startsHumongous()) {
6813 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6814 _humongous_count.increment(1u, hr->capacity());
6815 } else if (hr->is_empty()) {
6816 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6817 _free_count.increment(1u, hr->capacity());
6818 } else if (hr->is_old()) {
6819 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6820 _old_count.increment(1u, hr->capacity());
6821 } else {
6822 ShouldNotReachHere();
6823 }
6824 return false;
6825 }
6826
6827 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6828 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6829 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6830 old_set->total_capacity_bytes(), _old_count.capacity()));
6831
6832 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6833 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6834 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6835
6836 guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
6837 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6838 free_list->total_capacity_bytes(), _free_count.capacity()));
6839 }
6840 };
6841
6842 void G1CollectedHeap::verify_region_sets() {
6843 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6844
6845 // First, check the explicit lists.
6846 _hrm.verify();
6847 {
6848 // Given that a concurrent operation might be adding regions to
6849 // the secondary free list we have to take the lock before
6850 // verifying it.
6851 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6852 _secondary_free_list.verify_list();
6853 }
6854
6855 // If a concurrent region freeing operation is in progress it will
6856 // be difficult to correctly attributed any free regions we come
6857 // across to the correct free list given that they might belong to
6858 // one of several (free_list, secondary_free_list, any local lists,
6859 // etc.). So, if that's the case we will skip the rest of the
6860 // verification operation. Alternatively, waiting for the concurrent
6861 // operation to complete will have a non-trivial effect on the GC's
6862 // operation (no concurrent operation will last longer than the
6863 // interval between two calls to verification) and it might hide
6864 // any issues that we would like to catch during testing.
6865 if (free_regions_coming()) {
6866 return;
6867 }
6868
6869 // Make sure we append the secondary_free_list on the free_list so
6870 // that all free regions we will come across can be safely
6871 // attributed to the free_list.
6872 append_secondary_free_list_if_not_empty_with_lock();
6873
6874 // Finally, make sure that the region accounting in the lists is
6875 // consistent with what we see in the heap.
6876
6877 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6878 heap_region_iterate(&cl);
6879 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6880 }
6881
6882 // Optimized nmethod scanning
6883
6884 class RegisterNMethodOopClosure: public OopClosure {
6885 G1CollectedHeap* _g1h;
6886 nmethod* _nm;
6887
6888 template <class T> void do_oop_work(T* p) {
6889 T heap_oop = oopDesc::load_heap_oop(p);
6890 if (!oopDesc::is_null(heap_oop)) {
6891 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6892 HeapRegion* hr = _g1h->heap_region_containing(obj);
6893 assert(!hr->continuesHumongous(),
6894 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6895 " starting at "HR_FORMAT,
6896 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6897
6898 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6899 hr->add_strong_code_root_locked(_nm);
6900 }
6901 }
6902
6903 public:
6904 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6905 _g1h(g1h), _nm(nm) {}
6906
6907 void do_oop(oop* p) { do_oop_work(p); }
6908 void do_oop(narrowOop* p) { do_oop_work(p); }
6909 };
6910
6911 class UnregisterNMethodOopClosure: public OopClosure {
6912 G1CollectedHeap* _g1h;
6913 nmethod* _nm;
6914
6915 template <class T> void do_oop_work(T* p) {
6916 T heap_oop = oopDesc::load_heap_oop(p);
6917 if (!oopDesc::is_null(heap_oop)) {
6918 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6919 HeapRegion* hr = _g1h->heap_region_containing(obj);
6920 assert(!hr->continuesHumongous(),
6921 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6922 " starting at "HR_FORMAT,
6923 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6924
6925 hr->remove_strong_code_root(_nm);
6926 }
6927 }
6928
6929 public:
6930 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6931 _g1h(g1h), _nm(nm) {}
6932
6933 void do_oop(oop* p) { do_oop_work(p); }
6934 void do_oop(narrowOop* p) { do_oop_work(p); }
6935 };
6936
6937 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6938 CollectedHeap::register_nmethod(nm);
6939
6940 guarantee(nm != NULL, "sanity");
6941 RegisterNMethodOopClosure reg_cl(this, nm);
6942 nm->oops_do(®_cl);
6943 }
6944
6945 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6946 CollectedHeap::unregister_nmethod(nm);
6947
6948 guarantee(nm != NULL, "sanity");
6949 UnregisterNMethodOopClosure reg_cl(this, nm);
6950 nm->oops_do(®_cl, true);
6951 }
6952
6953 void G1CollectedHeap::purge_code_root_memory() {
6954 double purge_start = os::elapsedTime();
6955 G1CodeRootSet::purge();
6956 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6957 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6958 }
6959
6960 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6961 G1CollectedHeap* _g1h;
6962
6963 public:
6964 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6965 _g1h(g1h) {}
6966
6967 void do_code_blob(CodeBlob* cb) {
6968 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6969 if (nm == NULL) {
6970 return;
6971 }
6972
6973 if (ScavengeRootsInCode) {
6974 _g1h->register_nmethod(nm);
6975 }
6976 }
6977 };
6978
6979 void G1CollectedHeap::rebuild_strong_code_roots() {
6980 RebuildStrongCodeRootClosure blob_cl(this);
6981 CodeCache::blobs_do(&blob_cl);
6982 }