1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 #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 (unsigned int 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 unsigned int dummy_gc_count_before;
831 int 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 (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
842 unsigned int 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 unsigned int *gc_count_before_ret,
895 int* 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 unsigned int 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 unsigned int * gc_count_before_ret,
1011 int* 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 unsigned int 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_is_live(),
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 _in_cset_fast_test(),
1869 _dirty_cards_region_list(NULL),
1870 _worker_cset_start_region(NULL),
1871 _worker_cset_start_region_time_stamp(NULL),
1872 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1873 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1874 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1875 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1876
1877 _g1h = this;
1878
1879 _allocator = G1Allocator::create_allocator(_g1h);
1880 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1881
1882 int n_queues = MAX2((int)ParallelGCThreads, 1);
1883 _task_queues = new RefToScanQueueSet(n_queues);
1884
1885 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1886 assert(n_rem_sets > 0, "Invariant.");
1887
1888 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1889 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1890 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1891
1892 for (int i = 0; i < n_queues; i++) {
1893 RefToScanQueue* q = new RefToScanQueue();
1894 q->initialize();
1895 _task_queues->register_queue(i, q);
1896 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1897 }
1898 clear_cset_start_regions();
1899
1900 // Initialize the G1EvacuationFailureALot counters and flags.
1901 NOT_PRODUCT(reset_evacuation_should_fail();)
1902
1903 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1904 }
1905
1906 jint G1CollectedHeap::initialize() {
1907 CollectedHeap::pre_initialize();
1908 os::enable_vtime();
1909
1910 G1Log::init();
1911
1912 // Necessary to satisfy locking discipline assertions.
1913
1914 MutexLocker x(Heap_lock);
1915
1916 // We have to initialize the printer before committing the heap, as
1917 // it will be used then.
1918 _hr_printer.set_active(G1PrintHeapRegions);
1919
1920 // While there are no constraints in the GC code that HeapWordSize
1921 // be any particular value, there are multiple other areas in the
1922 // system which believe this to be true (e.g. oop->object_size in some
1923 // cases incorrectly returns the size in wordSize units rather than
1924 // HeapWordSize).
1925 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1926
1927 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1928 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1929 size_t heap_alignment = collector_policy()->heap_alignment();
1930
1931 // Ensure that the sizes are properly aligned.
1932 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1933 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1934 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1935
1936 _refine_cte_cl = new RefineCardTableEntryClosure();
1937
1938 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1939
1940 // Reserve the maximum.
1941
1942 // When compressed oops are enabled, the preferred heap base
1943 // is calculated by subtracting the requested size from the
1944 // 32Gb boundary and using the result as the base address for
1945 // heap reservation. If the requested size is not aligned to
1946 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1947 // into the ReservedHeapSpace constructor) then the actual
1948 // base of the reserved heap may end up differing from the
1949 // address that was requested (i.e. the preferred heap base).
1950 // If this happens then we could end up using a non-optimal
1951 // compressed oops mode.
1952
1953 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1954 heap_alignment);
1955
1956 // It is important to do this in a way such that concurrent readers can't
1957 // temporarily think something is in the heap. (I've actually seen this
1958 // happen in asserts: DLD.)
1959 _reserved.set_word_size(0);
1960 _reserved.set_start((HeapWord*)heap_rs.base());
1961 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1962
1963 // Create the gen rem set (and barrier set) for the entire reserved region.
1964 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1965 set_barrier_set(rem_set()->bs());
1966 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1967 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1968 return JNI_ENOMEM;
1969 }
1970
1971 // Also create a G1 rem set.
1972 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1973
1974 // Carve out the G1 part of the heap.
1975
1976 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1977 G1RegionToSpaceMapper* heap_storage =
1978 G1RegionToSpaceMapper::create_mapper(g1_rs,
1979 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1980 HeapRegion::GrainBytes,
1981 1,
1982 mtJavaHeap);
1983 heap_storage->set_mapping_changed_listener(&_listener);
1984
1985 // Reserve space for the block offset table. We do not support automatic uncommit
1986 // for the card table at this time. BOT only.
1987 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1988 G1RegionToSpaceMapper* bot_storage =
1989 G1RegionToSpaceMapper::create_mapper(bot_rs,
1990 os::vm_page_size(),
1991 HeapRegion::GrainBytes,
1992 G1BlockOffsetSharedArray::N_bytes,
1993 mtGC);
1994
1995 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1996 G1RegionToSpaceMapper* cardtable_storage =
1997 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1998 os::vm_page_size(),
1999 HeapRegion::GrainBytes,
2000 G1BlockOffsetSharedArray::N_bytes,
2001 mtGC);
2002
2003 // Reserve space for the card counts table.
2004 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
2005 G1RegionToSpaceMapper* card_counts_storage =
2006 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
2007 os::vm_page_size(),
2008 HeapRegion::GrainBytes,
2009 G1BlockOffsetSharedArray::N_bytes,
2010 mtGC);
2011
2012 // Reserve space for prev and next bitmap.
2013 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2014
2015 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2016 G1RegionToSpaceMapper* prev_bitmap_storage =
2017 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
2018 os::vm_page_size(),
2019 HeapRegion::GrainBytes,
2020 CMBitMap::mark_distance(),
2021 mtGC);
2022
2023 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2024 G1RegionToSpaceMapper* next_bitmap_storage =
2025 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
2026 os::vm_page_size(),
2027 HeapRegion::GrainBytes,
2028 CMBitMap::mark_distance(),
2029 mtGC);
2030
2031 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2032 g1_barrier_set()->initialize(cardtable_storage);
2033 // Do later initialization work for concurrent refinement.
2034 _cg1r->init(card_counts_storage);
2035
2036 // 6843694 - ensure that the maximum region index can fit
2037 // in the remembered set structures.
2038 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2039 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2040
2041 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2042 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2043 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2044 "too many cards per region");
2045
2046 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2047
2048 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
2049
2050 _g1h = this;
2051
2052 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2053 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2054
2055 // Create the ConcurrentMark data structure and thread.
2056 // (Must do this late, so that "max_regions" is defined.)
2057 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2058 if (_cm == NULL || !_cm->completed_initialization()) {
2059 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2060 return JNI_ENOMEM;
2061 }
2062 _cmThread = _cm->cmThread();
2063
2064 // Initialize the from_card cache structure of HeapRegionRemSet.
2065 HeapRegionRemSet::init_heap(max_regions());
2066
2067 // Now expand into the initial heap size.
2068 if (!expand(init_byte_size)) {
2069 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2070 return JNI_ENOMEM;
2071 }
2072
2073 // Perform any initialization actions delegated to the policy.
2074 g1_policy()->init();
2075
2076 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2077 SATB_Q_FL_lock,
2078 G1SATBProcessCompletedThreshold,
2079 Shared_SATB_Q_lock);
2080
2081 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2082 DirtyCardQ_CBL_mon,
2083 DirtyCardQ_FL_lock,
2084 concurrent_g1_refine()->yellow_zone(),
2085 concurrent_g1_refine()->red_zone(),
2086 Shared_DirtyCardQ_lock);
2087
2088 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2089 DirtyCardQ_CBL_mon,
2090 DirtyCardQ_FL_lock,
2091 -1, // never trigger processing
2092 -1, // no limit on length
2093 Shared_DirtyCardQ_lock,
2094 &JavaThread::dirty_card_queue_set());
2095
2096 // Initialize the card queue set used to hold cards containing
2097 // references into the collection set.
2098 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2099 DirtyCardQ_CBL_mon,
2100 DirtyCardQ_FL_lock,
2101 -1, // never trigger processing
2102 -1, // no limit on length
2103 Shared_DirtyCardQ_lock,
2104 &JavaThread::dirty_card_queue_set());
2105
2106 // In case we're keeping closure specialization stats, initialize those
2107 // counts and that mechanism.
2108 SpecializationStats::clear();
2109
2110 // Here we allocate the dummy HeapRegion that is required by the
2111 // G1AllocRegion class.
2112 HeapRegion* dummy_region = _hrm.get_dummy_region();
2113
2114 // We'll re-use the same region whether the alloc region will
2115 // require BOT updates or not and, if it doesn't, then a non-young
2116 // region will complain that it cannot support allocations without
2117 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2118 dummy_region->set_eden();
2119 // Make sure it's full.
2120 dummy_region->set_top(dummy_region->end());
2121 G1AllocRegion::setup(this, dummy_region);
2122
2123 _allocator->init_mutator_alloc_region();
2124
2125 // Do create of the monitoring and management support so that
2126 // values in the heap have been properly initialized.
2127 _g1mm = new G1MonitoringSupport(this);
2128
2129 G1StringDedup::initialize();
2130
2131 return JNI_OK;
2132 }
2133
2134 void G1CollectedHeap::stop() {
2135 // Stop all concurrent threads. We do this to make sure these threads
2136 // do not continue to execute and access resources (e.g. gclog_or_tty)
2137 // that are destroyed during shutdown.
2138 _cg1r->stop();
2139 _cmThread->stop();
2140 if (G1StringDedup::is_enabled()) {
2141 G1StringDedup::stop();
2142 }
2143 }
2144
2145 void G1CollectedHeap::clear_humongous_is_live_table() {
2146 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2147 _humongous_is_live.clear();
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 _concurrent_cycle_started = false;
2436 }
2437 }
2438
2439 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2440 if (_concurrent_cycle_started) {
2441 trace_heap_after_gc(_gc_tracer_cm);
2442 }
2443 }
2444
2445 G1YCType G1CollectedHeap::yc_type() {
2446 bool is_young = g1_policy()->gcs_are_young();
2447 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2448 bool is_during_mark = mark_in_progress();
2449
2450 if (is_initial_mark) {
2451 return InitialMark;
2452 } else if (is_during_mark) {
2453 return DuringMark;
2454 } else if (is_young) {
2455 return Normal;
2456 } else {
2457 return Mixed;
2458 }
2459 }
2460
2461 void G1CollectedHeap::collect(GCCause::Cause cause) {
2462 assert_heap_not_locked();
2463
2464 unsigned int gc_count_before;
2465 unsigned int old_marking_count_before;
2466 unsigned int full_gc_count_before;
2467 bool retry_gc;
2468
2469 do {
2470 retry_gc = false;
2471
2472 {
2473 MutexLocker ml(Heap_lock);
2474
2475 // Read the GC count while holding the Heap_lock
2476 gc_count_before = total_collections();
2477 full_gc_count_before = total_full_collections();
2478 old_marking_count_before = _old_marking_cycles_started;
2479 }
2480
2481 if (should_do_concurrent_full_gc(cause)) {
2482 // Schedule an initial-mark evacuation pause that will start a
2483 // concurrent cycle. We're setting word_size to 0 which means that
2484 // we are not requesting a post-GC allocation.
2485 VM_G1IncCollectionPause op(gc_count_before,
2486 0, /* word_size */
2487 true, /* should_initiate_conc_mark */
2488 g1_policy()->max_pause_time_ms(),
2489 cause);
2490 op.set_allocation_context(AllocationContext::current());
2491
2492 VMThread::execute(&op);
2493 if (!op.pause_succeeded()) {
2494 if (old_marking_count_before == _old_marking_cycles_started) {
2495 retry_gc = op.should_retry_gc();
2496 } else {
2497 // A Full GC happened while we were trying to schedule the
2498 // initial-mark GC. No point in starting a new cycle given
2499 // that the whole heap was collected anyway.
2500 }
2501
2502 if (retry_gc) {
2503 if (GC_locker::is_active_and_needs_gc()) {
2504 GC_locker::stall_until_clear();
2505 }
2506 }
2507 }
2508 } else {
2509 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2510 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2511
2512 // Schedule a standard evacuation pause. We're setting word_size
2513 // to 0 which means that we are not requesting a post-GC allocation.
2514 VM_G1IncCollectionPause op(gc_count_before,
2515 0, /* word_size */
2516 false, /* should_initiate_conc_mark */
2517 g1_policy()->max_pause_time_ms(),
2518 cause);
2519 VMThread::execute(&op);
2520 } else {
2521 // Schedule a Full GC.
2522 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2523 VMThread::execute(&op);
2524 }
2525 }
2526 } while (retry_gc);
2527 }
2528
2529 bool G1CollectedHeap::is_in(const void* p) const {
2530 if (_hrm.reserved().contains(p)) {
2531 // Given that we know that p is in the reserved space,
2532 // heap_region_containing_raw() should successfully
2533 // return the containing region.
2534 HeapRegion* hr = heap_region_containing_raw(p);
2535 return hr->is_in(p);
2536 } else {
2537 return false;
2538 }
2539 }
2540
2541 #ifdef ASSERT
2542 bool G1CollectedHeap::is_in_exact(const void* p) const {
2543 bool contains = reserved_region().contains(p);
2544 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2545 if (contains && available) {
2546 return true;
2547 } else {
2548 return false;
2549 }
2550 }
2551 #endif
2552
2553 // Iteration functions.
2554
2555 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2556
2557 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2558 ExtendedOopClosure* _cl;
2559 public:
2560 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2561 bool doHeapRegion(HeapRegion* r) {
2562 if (!r->continuesHumongous()) {
2563 r->oop_iterate(_cl);
2564 }
2565 return false;
2566 }
2567 };
2568
2569 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2570 IterateOopClosureRegionClosure blk(cl);
2571 heap_region_iterate(&blk);
2572 }
2573
2574 // Iterates an ObjectClosure over all objects within a HeapRegion.
2575
2576 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2577 ObjectClosure* _cl;
2578 public:
2579 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2580 bool doHeapRegion(HeapRegion* r) {
2581 if (! r->continuesHumongous()) {
2582 r->object_iterate(_cl);
2583 }
2584 return false;
2585 }
2586 };
2587
2588 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2589 IterateObjectClosureRegionClosure blk(cl);
2590 heap_region_iterate(&blk);
2591 }
2592
2593 // Calls a SpaceClosure on a HeapRegion.
2594
2595 class SpaceClosureRegionClosure: public HeapRegionClosure {
2596 SpaceClosure* _cl;
2597 public:
2598 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2599 bool doHeapRegion(HeapRegion* r) {
2600 _cl->do_space(r);
2601 return false;
2602 }
2603 };
2604
2605 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2606 SpaceClosureRegionClosure blk(cl);
2607 heap_region_iterate(&blk);
2608 }
2609
2610 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2611 _hrm.iterate(cl);
2612 }
2613
2614 void
2615 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2616 uint worker_id,
2617 uint num_workers,
2618 jint claim_value) const {
2619 _hrm.par_iterate(cl, worker_id, num_workers, claim_value);
2620 }
2621
2622 class ResetClaimValuesClosure: public HeapRegionClosure {
2623 public:
2624 bool doHeapRegion(HeapRegion* r) {
2625 r->set_claim_value(HeapRegion::InitialClaimValue);
2626 return false;
2627 }
2628 };
2629
2630 void G1CollectedHeap::reset_heap_region_claim_values() {
2631 ResetClaimValuesClosure blk;
2632 heap_region_iterate(&blk);
2633 }
2634
2635 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2636 ResetClaimValuesClosure blk;
2637 collection_set_iterate(&blk);
2638 }
2639
2640 #ifdef ASSERT
2641 // This checks whether all regions in the heap have the correct claim
2642 // value. I also piggy-backed on this a check to ensure that the
2643 // humongous_start_region() information on "continues humongous"
2644 // regions is correct.
2645
2646 class CheckClaimValuesClosure : public HeapRegionClosure {
2647 private:
2648 jint _claim_value;
2649 uint _failures;
2650 HeapRegion* _sh_region;
2651
2652 public:
2653 CheckClaimValuesClosure(jint claim_value) :
2654 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2655 bool doHeapRegion(HeapRegion* r) {
2656 if (r->claim_value() != _claim_value) {
2657 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2658 "claim value = %d, should be %d",
2659 HR_FORMAT_PARAMS(r),
2660 r->claim_value(), _claim_value);
2661 ++_failures;
2662 }
2663 if (!r->isHumongous()) {
2664 _sh_region = NULL;
2665 } else if (r->startsHumongous()) {
2666 _sh_region = r;
2667 } else if (r->continuesHumongous()) {
2668 if (r->humongous_start_region() != _sh_region) {
2669 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2670 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2671 HR_FORMAT_PARAMS(r),
2672 r->humongous_start_region(),
2673 _sh_region);
2674 ++_failures;
2675 }
2676 }
2677 return false;
2678 }
2679 uint failures() { return _failures; }
2680 };
2681
2682 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2683 CheckClaimValuesClosure cl(claim_value);
2684 heap_region_iterate(&cl);
2685 return cl.failures() == 0;
2686 }
2687
2688 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2689 private:
2690 jint _claim_value;
2691 uint _failures;
2692
2693 public:
2694 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2695 _claim_value(claim_value), _failures(0) { }
2696
2697 uint failures() { return _failures; }
2698
2699 bool doHeapRegion(HeapRegion* hr) {
2700 assert(hr->in_collection_set(), "how?");
2701 assert(!hr->isHumongous(), "H-region in CSet");
2702 if (hr->claim_value() != _claim_value) {
2703 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2704 "claim value = %d, should be %d",
2705 HR_FORMAT_PARAMS(hr),
2706 hr->claim_value(), _claim_value);
2707 _failures += 1;
2708 }
2709 return false;
2710 }
2711 };
2712
2713 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2714 CheckClaimValuesInCSetHRClosure cl(claim_value);
2715 collection_set_iterate(&cl);
2716 return cl.failures() == 0;
2717 }
2718 #endif // ASSERT
2719
2720 // Clear the cached CSet starting regions and (more importantly)
2721 // the time stamps. Called when we reset the GC time stamp.
2722 void G1CollectedHeap::clear_cset_start_regions() {
2723 assert(_worker_cset_start_region != NULL, "sanity");
2724 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2725
2726 int n_queues = MAX2((int)ParallelGCThreads, 1);
2727 for (int i = 0; i < n_queues; i++) {
2728 _worker_cset_start_region[i] = NULL;
2729 _worker_cset_start_region_time_stamp[i] = 0;
2730 }
2731 }
2732
2733 // Given the id of a worker, obtain or calculate a suitable
2734 // starting region for iterating over the current collection set.
2735 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2736 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2737
2738 HeapRegion* result = NULL;
2739 unsigned gc_time_stamp = get_gc_time_stamp();
2740
2741 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2742 // Cached starting region for current worker was set
2743 // during the current pause - so it's valid.
2744 // Note: the cached starting heap region may be NULL
2745 // (when the collection set is empty).
2746 result = _worker_cset_start_region[worker_i];
2747 assert(result == NULL || result->in_collection_set(), "sanity");
2748 return result;
2749 }
2750
2751 // The cached entry was not valid so let's calculate
2752 // a suitable starting heap region for this worker.
2753
2754 // We want the parallel threads to start their collection
2755 // set iteration at different collection set regions to
2756 // avoid contention.
2757 // If we have:
2758 // n collection set regions
2759 // p threads
2760 // Then thread t will start at region floor ((t * n) / p)
2761
2762 result = g1_policy()->collection_set();
2763 if (G1CollectedHeap::use_parallel_gc_threads()) {
2764 uint cs_size = g1_policy()->cset_region_length();
2765 uint active_workers = workers()->active_workers();
2766 assert(UseDynamicNumberOfGCThreads ||
2767 active_workers == workers()->total_workers(),
2768 "Unless dynamic should use total workers");
2769
2770 uint end_ind = (cs_size * worker_i) / active_workers;
2771 uint start_ind = 0;
2772
2773 if (worker_i > 0 &&
2774 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2775 // Previous workers starting region is valid
2776 // so let's iterate from there
2777 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2778 result = _worker_cset_start_region[worker_i - 1];
2779 }
2780
2781 for (uint i = start_ind; i < end_ind; i++) {
2782 result = result->next_in_collection_set();
2783 }
2784 }
2785
2786 // Note: the calculated starting heap region may be NULL
2787 // (when the collection set is empty).
2788 assert(result == NULL || result->in_collection_set(), "sanity");
2789 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2790 "should be updated only once per pause");
2791 _worker_cset_start_region[worker_i] = result;
2792 OrderAccess::storestore();
2793 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2794 return result;
2795 }
2796
2797 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2798 HeapRegion* r = g1_policy()->collection_set();
2799 while (r != NULL) {
2800 HeapRegion* next = r->next_in_collection_set();
2801 if (cl->doHeapRegion(r)) {
2802 cl->incomplete();
2803 return;
2804 }
2805 r = next;
2806 }
2807 }
2808
2809 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2810 HeapRegionClosure *cl) {
2811 if (r == NULL) {
2812 // The CSet is empty so there's nothing to do.
2813 return;
2814 }
2815
2816 assert(r->in_collection_set(),
2817 "Start region must be a member of the collection set.");
2818 HeapRegion* cur = r;
2819 while (cur != NULL) {
2820 HeapRegion* next = cur->next_in_collection_set();
2821 if (cl->doHeapRegion(cur) && false) {
2822 cl->incomplete();
2823 return;
2824 }
2825 cur = next;
2826 }
2827 cur = g1_policy()->collection_set();
2828 while (cur != r) {
2829 HeapRegion* next = cur->next_in_collection_set();
2830 if (cl->doHeapRegion(cur) && false) {
2831 cl->incomplete();
2832 return;
2833 }
2834 cur = next;
2835 }
2836 }
2837
2838 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2839 HeapRegion* result = _hrm.next_region_in_heap(from);
2840 while (result != NULL && result->isHumongous()) {
2841 result = _hrm.next_region_in_heap(result);
2842 }
2843 return result;
2844 }
2845
2846 Space* G1CollectedHeap::space_containing(const void* addr) const {
2847 return heap_region_containing(addr);
2848 }
2849
2850 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2851 Space* sp = space_containing(addr);
2852 return sp->block_start(addr);
2853 }
2854
2855 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2856 Space* sp = space_containing(addr);
2857 return sp->block_size(addr);
2858 }
2859
2860 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2861 Space* sp = space_containing(addr);
2862 return sp->block_is_obj(addr);
2863 }
2864
2865 bool G1CollectedHeap::supports_tlab_allocation() const {
2866 return true;
2867 }
2868
2869 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2870 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2871 }
2872
2873 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2874 return young_list()->eden_used_bytes();
2875 }
2876
2877 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2878 // must be smaller than the humongous object limit.
2879 size_t G1CollectedHeap::max_tlab_size() const {
2880 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2881 }
2882
2883 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2884 // Return the remaining space in the cur alloc region, but not less than
2885 // the min TLAB size.
2886
2887 // Also, this value can be at most the humongous object threshold,
2888 // since we can't allow tlabs to grow big enough to accommodate
2889 // humongous objects.
2890
2891 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2892 size_t max_tlab = max_tlab_size() * wordSize;
2893 if (hr == NULL) {
2894 return max_tlab;
2895 } else {
2896 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2897 }
2898 }
2899
2900 size_t G1CollectedHeap::max_capacity() const {
2901 return _hrm.reserved().byte_size();
2902 }
2903
2904 jlong G1CollectedHeap::millis_since_last_gc() {
2905 // assert(false, "NYI");
2906 return 0;
2907 }
2908
2909 void G1CollectedHeap::prepare_for_verify() {
2910 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2911 ensure_parsability(false);
2912 }
2913 g1_rem_set()->prepare_for_verify();
2914 }
2915
2916 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2917 VerifyOption vo) {
2918 switch (vo) {
2919 case VerifyOption_G1UsePrevMarking:
2920 return hr->obj_allocated_since_prev_marking(obj);
2921 case VerifyOption_G1UseNextMarking:
2922 return hr->obj_allocated_since_next_marking(obj);
2923 case VerifyOption_G1UseMarkWord:
2924 return false;
2925 default:
2926 ShouldNotReachHere();
2927 }
2928 return false; // keep some compilers happy
2929 }
2930
2931 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2932 switch (vo) {
2933 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2934 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2935 case VerifyOption_G1UseMarkWord: return NULL;
2936 default: ShouldNotReachHere();
2937 }
2938 return NULL; // keep some compilers happy
2939 }
2940
2941 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2942 switch (vo) {
2943 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2944 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2945 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2946 default: ShouldNotReachHere();
2947 }
2948 return false; // keep some compilers happy
2949 }
2950
2951 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2952 switch (vo) {
2953 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2954 case VerifyOption_G1UseNextMarking: return "NTAMS";
2955 case VerifyOption_G1UseMarkWord: return "NONE";
2956 default: ShouldNotReachHere();
2957 }
2958 return NULL; // keep some compilers happy
2959 }
2960
2961 class VerifyRootsClosure: public OopClosure {
2962 private:
2963 G1CollectedHeap* _g1h;
2964 VerifyOption _vo;
2965 bool _failures;
2966 public:
2967 // _vo == UsePrevMarking -> use "prev" marking information,
2968 // _vo == UseNextMarking -> use "next" marking information,
2969 // _vo == UseMarkWord -> use mark word from object header.
2970 VerifyRootsClosure(VerifyOption vo) :
2971 _g1h(G1CollectedHeap::heap()),
2972 _vo(vo),
2973 _failures(false) { }
2974
2975 bool failures() { return _failures; }
2976
2977 template <class T> void do_oop_nv(T* p) {
2978 T heap_oop = oopDesc::load_heap_oop(p);
2979 if (!oopDesc::is_null(heap_oop)) {
2980 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2981 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2982 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2983 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2984 if (_vo == VerifyOption_G1UseMarkWord) {
2985 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2986 }
2987 obj->print_on(gclog_or_tty);
2988 _failures = true;
2989 }
2990 }
2991 }
2992
2993 void do_oop(oop* p) { do_oop_nv(p); }
2994 void do_oop(narrowOop* p) { do_oop_nv(p); }
2995 };
2996
2997 class G1VerifyCodeRootOopClosure: public OopClosure {
2998 G1CollectedHeap* _g1h;
2999 OopClosure* _root_cl;
3000 nmethod* _nm;
3001 VerifyOption _vo;
3002 bool _failures;
3003
3004 template <class T> void do_oop_work(T* p) {
3005 // First verify that this root is live
3006 _root_cl->do_oop(p);
3007
3008 if (!G1VerifyHeapRegionCodeRoots) {
3009 // We're not verifying the code roots attached to heap region.
3010 return;
3011 }
3012
3013 // Don't check the code roots during marking verification in a full GC
3014 if (_vo == VerifyOption_G1UseMarkWord) {
3015 return;
3016 }
3017
3018 // Now verify that the current nmethod (which contains p) is
3019 // in the code root list of the heap region containing the
3020 // object referenced by p.
3021
3022 T heap_oop = oopDesc::load_heap_oop(p);
3023 if (!oopDesc::is_null(heap_oop)) {
3024 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3025
3026 // Now fetch the region containing the object
3027 HeapRegion* hr = _g1h->heap_region_containing(obj);
3028 HeapRegionRemSet* hrrs = hr->rem_set();
3029 // Verify that the strong code root list for this region
3030 // contains the nmethod
3031 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3032 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3033 "from nmethod "PTR_FORMAT" not in strong "
3034 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3035 p, _nm, hr->bottom(), hr->end());
3036 _failures = true;
3037 }
3038 }
3039 }
3040
3041 public:
3042 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3043 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3044
3045 void do_oop(oop* p) { do_oop_work(p); }
3046 void do_oop(narrowOop* p) { do_oop_work(p); }
3047
3048 void set_nmethod(nmethod* nm) { _nm = nm; }
3049 bool failures() { return _failures; }
3050 };
3051
3052 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3053 G1VerifyCodeRootOopClosure* _oop_cl;
3054
3055 public:
3056 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3057 _oop_cl(oop_cl) {}
3058
3059 void do_code_blob(CodeBlob* cb) {
3060 nmethod* nm = cb->as_nmethod_or_null();
3061 if (nm != NULL) {
3062 _oop_cl->set_nmethod(nm);
3063 nm->oops_do(_oop_cl);
3064 }
3065 }
3066 };
3067
3068 class YoungRefCounterClosure : public OopClosure {
3069 G1CollectedHeap* _g1h;
3070 int _count;
3071 public:
3072 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3073 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3074 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3075
3076 int count() { return _count; }
3077 void reset_count() { _count = 0; };
3078 };
3079
3080 class VerifyKlassClosure: public KlassClosure {
3081 YoungRefCounterClosure _young_ref_counter_closure;
3082 OopClosure *_oop_closure;
3083 public:
3084 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3085 void do_klass(Klass* k) {
3086 k->oops_do(_oop_closure);
3087
3088 _young_ref_counter_closure.reset_count();
3089 k->oops_do(&_young_ref_counter_closure);
3090 if (_young_ref_counter_closure.count() > 0) {
3091 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3092 }
3093 }
3094 };
3095
3096 class VerifyLivenessOopClosure: public OopClosure {
3097 G1CollectedHeap* _g1h;
3098 VerifyOption _vo;
3099 public:
3100 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3101 _g1h(g1h), _vo(vo)
3102 { }
3103 void do_oop(narrowOop *p) { do_oop_work(p); }
3104 void do_oop( oop *p) { do_oop_work(p); }
3105
3106 template <class T> void do_oop_work(T *p) {
3107 oop obj = oopDesc::load_decode_heap_oop(p);
3108 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3109 "Dead object referenced by a not dead object");
3110 }
3111 };
3112
3113 class VerifyObjsInRegionClosure: public ObjectClosure {
3114 private:
3115 G1CollectedHeap* _g1h;
3116 size_t _live_bytes;
3117 HeapRegion *_hr;
3118 VerifyOption _vo;
3119 public:
3120 // _vo == UsePrevMarking -> use "prev" marking information,
3121 // _vo == UseNextMarking -> use "next" marking information,
3122 // _vo == UseMarkWord -> use mark word from object header.
3123 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3124 : _live_bytes(0), _hr(hr), _vo(vo) {
3125 _g1h = G1CollectedHeap::heap();
3126 }
3127 void do_object(oop o) {
3128 VerifyLivenessOopClosure isLive(_g1h, _vo);
3129 assert(o != NULL, "Huh?");
3130 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3131 // If the object is alive according to the mark word,
3132 // then verify that the marking information agrees.
3133 // Note we can't verify the contra-positive of the
3134 // above: if the object is dead (according to the mark
3135 // word), it may not be marked, or may have been marked
3136 // but has since became dead, or may have been allocated
3137 // since the last marking.
3138 if (_vo == VerifyOption_G1UseMarkWord) {
3139 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3140 }
3141
3142 o->oop_iterate_no_header(&isLive);
3143 if (!_hr->obj_allocated_since_prev_marking(o)) {
3144 size_t obj_size = o->size(); // Make sure we don't overflow
3145 _live_bytes += (obj_size * HeapWordSize);
3146 }
3147 }
3148 }
3149 size_t live_bytes() { return _live_bytes; }
3150 };
3151
3152 class PrintObjsInRegionClosure : public ObjectClosure {
3153 HeapRegion *_hr;
3154 G1CollectedHeap *_g1;
3155 public:
3156 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3157 _g1 = G1CollectedHeap::heap();
3158 };
3159
3160 void do_object(oop o) {
3161 if (o != NULL) {
3162 HeapWord *start = (HeapWord *) o;
3163 size_t word_sz = o->size();
3164 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3165 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3166 (void*) o, word_sz,
3167 _g1->isMarkedPrev(o),
3168 _g1->isMarkedNext(o),
3169 _hr->obj_allocated_since_prev_marking(o));
3170 HeapWord *end = start + word_sz;
3171 HeapWord *cur;
3172 int *val;
3173 for (cur = start; cur < end; cur++) {
3174 val = (int *) cur;
3175 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3176 }
3177 }
3178 }
3179 };
3180
3181 class VerifyRegionClosure: public HeapRegionClosure {
3182 private:
3183 bool _par;
3184 VerifyOption _vo;
3185 bool _failures;
3186 public:
3187 // _vo == UsePrevMarking -> use "prev" marking information,
3188 // _vo == UseNextMarking -> use "next" marking information,
3189 // _vo == UseMarkWord -> use mark word from object header.
3190 VerifyRegionClosure(bool par, VerifyOption vo)
3191 : _par(par),
3192 _vo(vo),
3193 _failures(false) {}
3194
3195 bool failures() {
3196 return _failures;
3197 }
3198
3199 bool doHeapRegion(HeapRegion* r) {
3200 if (!r->continuesHumongous()) {
3201 bool failures = false;
3202 r->verify(_vo, &failures);
3203 if (failures) {
3204 _failures = true;
3205 } else {
3206 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3207 r->object_iterate(¬_dead_yet_cl);
3208 if (_vo != VerifyOption_G1UseNextMarking) {
3209 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3210 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3211 "max_live_bytes "SIZE_FORMAT" "
3212 "< calculated "SIZE_FORMAT,
3213 r->bottom(), r->end(),
3214 r->max_live_bytes(),
3215 not_dead_yet_cl.live_bytes());
3216 _failures = true;
3217 }
3218 } else {
3219 // When vo == UseNextMarking we cannot currently do a sanity
3220 // check on the live bytes as the calculation has not been
3221 // finalized yet.
3222 }
3223 }
3224 }
3225 return false; // stop the region iteration if we hit a failure
3226 }
3227 };
3228
3229 // This is the task used for parallel verification of the heap regions
3230
3231 class G1ParVerifyTask: public AbstractGangTask {
3232 private:
3233 G1CollectedHeap* _g1h;
3234 VerifyOption _vo;
3235 bool _failures;
3236
3237 public:
3238 // _vo == UsePrevMarking -> use "prev" marking information,
3239 // _vo == UseNextMarking -> use "next" marking information,
3240 // _vo == UseMarkWord -> use mark word from object header.
3241 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3242 AbstractGangTask("Parallel verify task"),
3243 _g1h(g1h),
3244 _vo(vo),
3245 _failures(false) { }
3246
3247 bool failures() {
3248 return _failures;
3249 }
3250
3251 void work(uint worker_id) {
3252 HandleMark hm;
3253 VerifyRegionClosure blk(true, _vo);
3254 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3255 _g1h->workers()->active_workers(),
3256 HeapRegion::ParVerifyClaimValue);
3257 if (blk.failures()) {
3258 _failures = true;
3259 }
3260 }
3261 };
3262
3263 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3264 if (SafepointSynchronize::is_at_safepoint()) {
3265 assert(Thread::current()->is_VM_thread(),
3266 "Expected to be executed serially by the VM thread at this point");
3267
3268 if (!silent) { gclog_or_tty->print("Roots "); }
3269 VerifyRootsClosure rootsCl(vo);
3270 VerifyKlassClosure klassCl(this, &rootsCl);
3271 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3272
3273 // We apply the relevant closures to all the oops in the
3274 // system dictionary, class loader data graph, the string table
3275 // and the nmethods in the code cache.
3276 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3277 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3278
3279 {
3280 G1RootProcessor root_processor(this);
3281 root_processor.process_all_roots(&rootsCl,
3282 &cldCl,
3283 &blobsCl);
3284 }
3285
3286 bool failures = rootsCl.failures() || codeRootsCl.failures();
3287
3288 if (vo != VerifyOption_G1UseMarkWord) {
3289 // If we're verifying during a full GC then the region sets
3290 // will have been torn down at the start of the GC. Therefore
3291 // verifying the region sets will fail. So we only verify
3292 // the region sets when not in a full GC.
3293 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3294 verify_region_sets();
3295 }
3296
3297 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3298 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3299 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3300 "sanity check");
3301
3302 G1ParVerifyTask task(this, vo);
3303 assert(UseDynamicNumberOfGCThreads ||
3304 workers()->active_workers() == workers()->total_workers(),
3305 "If not dynamic should be using all the workers");
3306 int n_workers = workers()->active_workers();
3307 set_par_threads(n_workers);
3308 workers()->run_task(&task);
3309 set_par_threads(0);
3310 if (task.failures()) {
3311 failures = true;
3312 }
3313
3314 // Checks that the expected amount of parallel work was done.
3315 // The implication is that n_workers is > 0.
3316 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3317 "sanity check");
3318
3319 reset_heap_region_claim_values();
3320
3321 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3322 "sanity check");
3323 } else {
3324 VerifyRegionClosure blk(false, vo);
3325 heap_region_iterate(&blk);
3326 if (blk.failures()) {
3327 failures = true;
3328 }
3329 }
3330 if (!silent) gclog_or_tty->print("RemSet ");
3331 rem_set()->verify();
3332
3333 if (G1StringDedup::is_enabled()) {
3334 if (!silent) gclog_or_tty->print("StrDedup ");
3335 G1StringDedup::verify();
3336 }
3337
3338 if (failures) {
3339 gclog_or_tty->print_cr("Heap:");
3340 // It helps to have the per-region information in the output to
3341 // help us track down what went wrong. This is why we call
3342 // print_extended_on() instead of print_on().
3343 print_extended_on(gclog_or_tty);
3344 gclog_or_tty->cr();
3345 #ifndef PRODUCT
3346 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3347 concurrent_mark()->print_reachable("at-verification-failure",
3348 vo, false /* all */);
3349 }
3350 #endif
3351 gclog_or_tty->flush();
3352 }
3353 guarantee(!failures, "there should not have been any failures");
3354 } else {
3355 if (!silent) {
3356 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3357 if (G1StringDedup::is_enabled()) {
3358 gclog_or_tty->print(", StrDedup");
3359 }
3360 gclog_or_tty->print(") ");
3361 }
3362 }
3363 }
3364
3365 void G1CollectedHeap::verify(bool silent) {
3366 verify(silent, VerifyOption_G1UsePrevMarking);
3367 }
3368
3369 double G1CollectedHeap::verify(bool guard, const char* msg) {
3370 double verify_time_ms = 0.0;
3371
3372 if (guard && total_collections() >= VerifyGCStartAt) {
3373 double verify_start = os::elapsedTime();
3374 HandleMark hm; // Discard invalid handles created during verification
3375 prepare_for_verify();
3376 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3377 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3378 }
3379
3380 return verify_time_ms;
3381 }
3382
3383 void G1CollectedHeap::verify_before_gc() {
3384 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3385 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3386 }
3387
3388 void G1CollectedHeap::verify_after_gc() {
3389 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3390 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3391 }
3392
3393 class PrintRegionClosure: public HeapRegionClosure {
3394 outputStream* _st;
3395 public:
3396 PrintRegionClosure(outputStream* st) : _st(st) {}
3397 bool doHeapRegion(HeapRegion* r) {
3398 r->print_on(_st);
3399 return false;
3400 }
3401 };
3402
3403 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3404 const HeapRegion* hr,
3405 const VerifyOption vo) const {
3406 switch (vo) {
3407 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3408 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3409 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3410 default: ShouldNotReachHere();
3411 }
3412 return false; // keep some compilers happy
3413 }
3414
3415 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3416 const VerifyOption vo) const {
3417 switch (vo) {
3418 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3419 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3420 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3421 default: ShouldNotReachHere();
3422 }
3423 return false; // keep some compilers happy
3424 }
3425
3426 void G1CollectedHeap::print_on(outputStream* st) const {
3427 st->print(" %-20s", "garbage-first heap");
3428 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3429 capacity()/K, used_unlocked()/K);
3430 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3431 _hrm.reserved().start(),
3432 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3433 _hrm.reserved().end());
3434 st->cr();
3435 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3436 uint young_regions = _young_list->length();
3437 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3438 (size_t) young_regions * HeapRegion::GrainBytes / K);
3439 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3440 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3441 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3442 st->cr();
3443 MetaspaceAux::print_on(st);
3444 }
3445
3446 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3447 print_on(st);
3448
3449 // Print the per-region information.
3450 st->cr();
3451 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3452 "HS=humongous(starts), HC=humongous(continues), "
3453 "CS=collection set, F=free, TS=gc time stamp, "
3454 "PTAMS=previous top-at-mark-start, "
3455 "NTAMS=next top-at-mark-start)");
3456 PrintRegionClosure blk(st);
3457 heap_region_iterate(&blk);
3458 }
3459
3460 void G1CollectedHeap::print_on_error(outputStream* st) const {
3461 this->CollectedHeap::print_on_error(st);
3462
3463 if (_cm != NULL) {
3464 st->cr();
3465 _cm->print_on_error(st);
3466 }
3467 }
3468
3469 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3470 if (G1CollectedHeap::use_parallel_gc_threads()) {
3471 workers()->print_worker_threads_on(st);
3472 }
3473 _cmThread->print_on(st);
3474 st->cr();
3475 _cm->print_worker_threads_on(st);
3476 _cg1r->print_worker_threads_on(st);
3477 if (G1StringDedup::is_enabled()) {
3478 G1StringDedup::print_worker_threads_on(st);
3479 }
3480 }
3481
3482 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3483 if (G1CollectedHeap::use_parallel_gc_threads()) {
3484 workers()->threads_do(tc);
3485 }
3486 tc->do_thread(_cmThread);
3487 _cg1r->threads_do(tc);
3488 if (G1StringDedup::is_enabled()) {
3489 G1StringDedup::threads_do(tc);
3490 }
3491 }
3492
3493 void G1CollectedHeap::print_tracing_info() const {
3494 // We'll overload this to mean "trace GC pause statistics."
3495 if (TraceGen0Time || TraceGen1Time) {
3496 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3497 // to that.
3498 g1_policy()->print_tracing_info();
3499 }
3500 if (G1SummarizeRSetStats) {
3501 g1_rem_set()->print_summary_info();
3502 }
3503 if (G1SummarizeConcMark) {
3504 concurrent_mark()->print_summary_info();
3505 }
3506 g1_policy()->print_yg_surv_rate_info();
3507 SpecializationStats::print();
3508 }
3509
3510 #ifndef PRODUCT
3511 // Helpful for debugging RSet issues.
3512
3513 class PrintRSetsClosure : public HeapRegionClosure {
3514 private:
3515 const char* _msg;
3516 size_t _occupied_sum;
3517
3518 public:
3519 bool doHeapRegion(HeapRegion* r) {
3520 HeapRegionRemSet* hrrs = r->rem_set();
3521 size_t occupied = hrrs->occupied();
3522 _occupied_sum += occupied;
3523
3524 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3525 HR_FORMAT_PARAMS(r));
3526 if (occupied == 0) {
3527 gclog_or_tty->print_cr(" RSet is empty");
3528 } else {
3529 hrrs->print();
3530 }
3531 gclog_or_tty->print_cr("----------");
3532 return false;
3533 }
3534
3535 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3536 gclog_or_tty->cr();
3537 gclog_or_tty->print_cr("========================================");
3538 gclog_or_tty->print_cr("%s", msg);
3539 gclog_or_tty->cr();
3540 }
3541
3542 ~PrintRSetsClosure() {
3543 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3544 gclog_or_tty->print_cr("========================================");
3545 gclog_or_tty->cr();
3546 }
3547 };
3548
3549 void G1CollectedHeap::print_cset_rsets() {
3550 PrintRSetsClosure cl("Printing CSet RSets");
3551 collection_set_iterate(&cl);
3552 }
3553
3554 void G1CollectedHeap::print_all_rsets() {
3555 PrintRSetsClosure cl("Printing All RSets");;
3556 heap_region_iterate(&cl);
3557 }
3558 #endif // PRODUCT
3559
3560 G1CollectedHeap* G1CollectedHeap::heap() {
3561 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3562 "not a garbage-first heap");
3563 return _g1h;
3564 }
3565
3566 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3567 // always_do_update_barrier = false;
3568 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3569 // Fill TLAB's and such
3570 accumulate_statistics_all_tlabs();
3571 ensure_parsability(true);
3572
3573 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3574 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3575 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3576 }
3577 }
3578
3579 void G1CollectedHeap::gc_epilogue(bool full) {
3580
3581 if (G1SummarizeRSetStats &&
3582 (G1SummarizeRSetStatsPeriod > 0) &&
3583 // we are at the end of the GC. Total collections has already been increased.
3584 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3585 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3586 }
3587
3588 // FIXME: what is this about?
3589 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3590 // is set.
3591 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3592 "derived pointer present"));
3593 // always_do_update_barrier = true;
3594
3595 resize_all_tlabs();
3596 allocation_context_stats().update(full);
3597
3598 // We have just completed a GC. Update the soft reference
3599 // policy with the new heap occupancy
3600 Universe::update_heap_info_at_gc();
3601 }
3602
3603 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3604 unsigned int gc_count_before,
3605 bool* succeeded,
3606 GCCause::Cause gc_cause) {
3607 assert_heap_not_locked_and_not_at_safepoint();
3608 g1_policy()->record_stop_world_start();
3609 VM_G1IncCollectionPause op(gc_count_before,
3610 word_size,
3611 false, /* should_initiate_conc_mark */
3612 g1_policy()->max_pause_time_ms(),
3613 gc_cause);
3614
3615 op.set_allocation_context(AllocationContext::current());
3616 VMThread::execute(&op);
3617
3618 HeapWord* result = op.result();
3619 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3620 assert(result == NULL || ret_succeeded,
3621 "the result should be NULL if the VM did not succeed");
3622 *succeeded = ret_succeeded;
3623
3624 assert_heap_not_locked();
3625 return result;
3626 }
3627
3628 void
3629 G1CollectedHeap::doConcurrentMark() {
3630 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3631 if (!_cmThread->in_progress()) {
3632 _cmThread->set_started();
3633 CGC_lock->notify();
3634 }
3635 }
3636
3637 size_t G1CollectedHeap::pending_card_num() {
3638 size_t extra_cards = 0;
3639 JavaThread *curr = Threads::first();
3640 while (curr != NULL) {
3641 DirtyCardQueue& dcq = curr->dirty_card_queue();
3642 extra_cards += dcq.size();
3643 curr = curr->next();
3644 }
3645 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3646 size_t buffer_size = dcqs.buffer_size();
3647 size_t buffer_num = dcqs.completed_buffers_num();
3648
3649 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3650 // in bytes - not the number of 'entries'. We need to convert
3651 // into a number of cards.
3652 return (buffer_size * buffer_num + extra_cards) / oopSize;
3653 }
3654
3655 size_t G1CollectedHeap::cards_scanned() {
3656 return g1_rem_set()->cardsScanned();
3657 }
3658
3659 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3660 HeapRegion* region = region_at(index);
3661 assert(region->startsHumongous(), "Must start a humongous object");
3662 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3663 }
3664
3665 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3666 private:
3667 size_t _total_humongous;
3668 size_t _candidate_humongous;
3669 public:
3670 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3671 }
3672
3673 virtual bool doHeapRegion(HeapRegion* r) {
3674 if (!r->startsHumongous()) {
3675 return false;
3676 }
3677 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3678
3679 uint region_idx = r->hrm_index();
3680 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3681 // Is_candidate already filters out humongous regions with some remembered set.
3682 // This will not lead to humongous object that we mistakenly keep alive because
3683 // during young collection the remembered sets will only be added to.
3684 if (is_candidate) {
3685 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3686 _candidate_humongous++;
3687 }
3688 _total_humongous++;
3689
3690 return false;
3691 }
3692
3693 size_t total_humongous() const { return _total_humongous; }
3694 size_t candidate_humongous() const { return _candidate_humongous; }
3695 };
3696
3697 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3698 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3699 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3700 return;
3701 }
3702
3703 RegisterHumongousWithInCSetFastTestClosure cl;
3704 heap_region_iterate(&cl);
3705 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3706 cl.candidate_humongous());
3707 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3708
3709 if (_has_humongous_reclaim_candidates || G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
3710 clear_humongous_is_live_table();
3711 }
3712 }
3713
3714 void
3715 G1CollectedHeap::setup_surviving_young_words() {
3716 assert(_surviving_young_words == NULL, "pre-condition");
3717 uint array_length = g1_policy()->young_cset_region_length();
3718 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3719 if (_surviving_young_words == NULL) {
3720 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3721 "Not enough space for young surv words summary.");
3722 }
3723 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3724 #ifdef ASSERT
3725 for (uint i = 0; i < array_length; ++i) {
3726 assert( _surviving_young_words[i] == 0, "memset above" );
3727 }
3728 #endif // !ASSERT
3729 }
3730
3731 void
3732 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3733 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3734 uint array_length = g1_policy()->young_cset_region_length();
3735 for (uint i = 0; i < array_length; ++i) {
3736 _surviving_young_words[i] += surv_young_words[i];
3737 }
3738 }
3739
3740 void
3741 G1CollectedHeap::cleanup_surviving_young_words() {
3742 guarantee( _surviving_young_words != NULL, "pre-condition" );
3743 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3744 _surviving_young_words = NULL;
3745 }
3746
3747 #ifdef ASSERT
3748 class VerifyCSetClosure: public HeapRegionClosure {
3749 public:
3750 bool doHeapRegion(HeapRegion* hr) {
3751 // Here we check that the CSet region's RSet is ready for parallel
3752 // iteration. The fields that we'll verify are only manipulated
3753 // when the region is part of a CSet and is collected. Afterwards,
3754 // we reset these fields when we clear the region's RSet (when the
3755 // region is freed) so they are ready when the region is
3756 // re-allocated. The only exception to this is if there's an
3757 // evacuation failure and instead of freeing the region we leave
3758 // it in the heap. In that case, we reset these fields during
3759 // evacuation failure handling.
3760 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3761
3762 // Here's a good place to add any other checks we'd like to
3763 // perform on CSet regions.
3764 return false;
3765 }
3766 };
3767 #endif // ASSERT
3768
3769 #if TASKQUEUE_STATS
3770 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3771 st->print_raw_cr("GC Task Stats");
3772 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3773 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3774 }
3775
3776 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3777 print_taskqueue_stats_hdr(st);
3778
3779 TaskQueueStats totals;
3780 const int n = workers() != NULL ? workers()->total_workers() : 1;
3781 for (int i = 0; i < n; ++i) {
3782 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3783 totals += task_queue(i)->stats;
3784 }
3785 st->print_raw("tot "); totals.print(st); st->cr();
3786
3787 DEBUG_ONLY(totals.verify());
3788 }
3789
3790 void G1CollectedHeap::reset_taskqueue_stats() {
3791 const int n = workers() != NULL ? workers()->total_workers() : 1;
3792 for (int i = 0; i < n; ++i) {
3793 task_queue(i)->stats.reset();
3794 }
3795 }
3796 #endif // TASKQUEUE_STATS
3797
3798 void G1CollectedHeap::log_gc_header() {
3799 if (!G1Log::fine()) {
3800 return;
3801 }
3802
3803 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3804
3805 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3806 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3807 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3808
3809 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3810 }
3811
3812 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3813 if (!G1Log::fine()) {
3814 return;
3815 }
3816
3817 if (G1Log::finer()) {
3818 if (evacuation_failed()) {
3819 gclog_or_tty->print(" (to-space exhausted)");
3820 }
3821 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3822 g1_policy()->phase_times()->note_gc_end();
3823 g1_policy()->phase_times()->print(pause_time_sec);
3824 g1_policy()->print_detailed_heap_transition();
3825 } else {
3826 if (evacuation_failed()) {
3827 gclog_or_tty->print("--");
3828 }
3829 g1_policy()->print_heap_transition();
3830 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3831 }
3832 gclog_or_tty->flush();
3833 }
3834
3835 bool
3836 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3837 assert_at_safepoint(true /* should_be_vm_thread */);
3838 guarantee(!is_gc_active(), "collection is not reentrant");
3839
3840 if (GC_locker::check_active_before_gc()) {
3841 return false;
3842 }
3843
3844 _gc_timer_stw->register_gc_start();
3845
3846 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3847
3848 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3849 ResourceMark rm;
3850
3851 print_heap_before_gc();
3852 trace_heap_before_gc(_gc_tracer_stw);
3853
3854 verify_region_sets_optional();
3855 verify_dirty_young_regions();
3856
3857 // This call will decide whether this pause is an initial-mark
3858 // pause. If it is, during_initial_mark_pause() will return true
3859 // for the duration of this pause.
3860 g1_policy()->decide_on_conc_mark_initiation();
3861
3862 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3863 assert(!g1_policy()->during_initial_mark_pause() ||
3864 g1_policy()->gcs_are_young(), "sanity");
3865
3866 // We also do not allow mixed GCs during marking.
3867 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3868
3869 // Record whether this pause is an initial mark. When the current
3870 // thread has completed its logging output and it's safe to signal
3871 // the CM thread, the flag's value in the policy has been reset.
3872 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3873
3874 // Inner scope for scope based logging, timers, and stats collection
3875 {
3876 EvacuationInfo evacuation_info;
3877
3878 if (g1_policy()->during_initial_mark_pause()) {
3879 // We are about to start a marking cycle, so we increment the
3880 // full collection counter.
3881 increment_old_marking_cycles_started();
3882 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3883 }
3884
3885 _gc_tracer_stw->report_yc_type(yc_type());
3886
3887 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3888
3889 uint active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3890 workers()->active_workers() : 1);
3891 double pause_start_sec = os::elapsedTime();
3892 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3893 log_gc_header();
3894
3895 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3896 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3897
3898 // If the secondary_free_list is not empty, append it to the
3899 // free_list. No need to wait for the cleanup operation to finish;
3900 // the region allocation code will check the secondary_free_list
3901 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3902 // set, skip this step so that the region allocation code has to
3903 // get entries from the secondary_free_list.
3904 if (!G1StressConcRegionFreeing) {
3905 append_secondary_free_list_if_not_empty_with_lock();
3906 }
3907
3908 assert(check_young_list_well_formed(), "young list should be well formed");
3909 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3910 "sanity check");
3911
3912 // Don't dynamically change the number of GC threads this early. A value of
3913 // 0 is used to indicate serial work. When parallel work is done,
3914 // it will be set.
3915
3916 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3917 IsGCActiveMark x;
3918
3919 gc_prologue(false);
3920 increment_total_collections(false /* full gc */);
3921 increment_gc_time_stamp();
3922
3923 verify_before_gc();
3924 check_bitmaps("GC Start");
3925
3926 COMPILER2_PRESENT(DerivedPointerTable::clear());
3927
3928 // Please see comment in g1CollectedHeap.hpp and
3929 // G1CollectedHeap::ref_processing_init() to see how
3930 // reference processing currently works in G1.
3931
3932 // Enable discovery in the STW reference processor
3933 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3934 true /*verify_no_refs*/);
3935
3936 {
3937 // We want to temporarily turn off discovery by the
3938 // CM ref processor, if necessary, and turn it back on
3939 // on again later if we do. Using a scoped
3940 // NoRefDiscovery object will do this.
3941 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3942
3943 // Forget the current alloc region (we might even choose it to be part
3944 // of the collection set!).
3945 _allocator->release_mutator_alloc_region();
3946
3947 // We should call this after we retire the mutator alloc
3948 // region(s) so that all the ALLOC / RETIRE events are generated
3949 // before the start GC event.
3950 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3951
3952 // This timing is only used by the ergonomics to handle our pause target.
3953 // It is unclear why this should not include the full pause. We will
3954 // investigate this in CR 7178365.
3955 //
3956 // Preserving the old comment here if that helps the investigation:
3957 //
3958 // The elapsed time induced by the start time below deliberately elides
3959 // the possible verification above.
3960 double sample_start_time_sec = os::elapsedTime();
3961
3962 #if YOUNG_LIST_VERBOSE
3963 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3964 _young_list->print();
3965 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3966 #endif // YOUNG_LIST_VERBOSE
3967
3968 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3969
3970 double scan_wait_start = os::elapsedTime();
3971 // We have to wait until the CM threads finish scanning the
3972 // root regions as it's the only way to ensure that all the
3973 // objects on them have been correctly scanned before we start
3974 // moving them during the GC.
3975 bool waited = _cm->root_regions()->wait_until_scan_finished();
3976 double wait_time_ms = 0.0;
3977 if (waited) {
3978 double scan_wait_end = os::elapsedTime();
3979 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3980 }
3981 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3982
3983 #if YOUNG_LIST_VERBOSE
3984 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3985 _young_list->print();
3986 #endif // YOUNG_LIST_VERBOSE
3987
3988 if (g1_policy()->during_initial_mark_pause()) {
3989 concurrent_mark()->checkpointRootsInitialPre();
3990 }
3991
3992 #if YOUNG_LIST_VERBOSE
3993 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3994 _young_list->print();
3995 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3996 #endif // YOUNG_LIST_VERBOSE
3997
3998 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3999
4000 register_humongous_regions_with_in_cset_fast_test();
4001
4002 _cm->note_start_of_gc();
4003 // We should not verify the per-thread SATB buffers given that
4004 // we have not filtered them yet (we'll do so during the
4005 // GC). We also call this after finalize_cset() to
4006 // ensure that the CSet has been finalized.
4007 _cm->verify_no_cset_oops(true /* verify_stacks */,
4008 true /* verify_enqueued_buffers */,
4009 false /* verify_thread_buffers */,
4010 true /* verify_fingers */);
4011
4012 if (_hr_printer.is_active()) {
4013 HeapRegion* hr = g1_policy()->collection_set();
4014 while (hr != NULL) {
4015 _hr_printer.cset(hr);
4016 hr = hr->next_in_collection_set();
4017 }
4018 }
4019
4020 #ifdef ASSERT
4021 VerifyCSetClosure cl;
4022 collection_set_iterate(&cl);
4023 #endif // ASSERT
4024
4025 setup_surviving_young_words();
4026
4027 // Initialize the GC alloc regions.
4028 _allocator->init_gc_alloc_regions(evacuation_info);
4029
4030 // Actually do the work...
4031 evacuate_collection_set(evacuation_info);
4032
4033 // We do this to mainly verify the per-thread SATB buffers
4034 // (which have been filtered by now) since we didn't verify
4035 // them earlier. No point in re-checking the stacks / enqueued
4036 // buffers given that the CSet has not changed since last time
4037 // we checked.
4038 _cm->verify_no_cset_oops(false /* verify_stacks */,
4039 false /* verify_enqueued_buffers */,
4040 true /* verify_thread_buffers */,
4041 true /* verify_fingers */);
4042
4043 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4044
4045 eagerly_reclaim_humongous_regions();
4046
4047 g1_policy()->clear_collection_set();
4048
4049 cleanup_surviving_young_words();
4050
4051 // Start a new incremental collection set for the next pause.
4052 g1_policy()->start_incremental_cset_building();
4053
4054 clear_cset_fast_test();
4055
4056 _young_list->reset_sampled_info();
4057
4058 // Don't check the whole heap at this point as the
4059 // GC alloc regions from this pause have been tagged
4060 // as survivors and moved on to the survivor list.
4061 // Survivor regions will fail the !is_young() check.
4062 assert(check_young_list_empty(false /* check_heap */),
4063 "young list should be empty");
4064
4065 #if YOUNG_LIST_VERBOSE
4066 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4067 _young_list->print();
4068 #endif // YOUNG_LIST_VERBOSE
4069
4070 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4071 _young_list->first_survivor_region(),
4072 _young_list->last_survivor_region());
4073
4074 _young_list->reset_auxilary_lists();
4075
4076 if (evacuation_failed()) {
4077 _allocator->set_used(recalculate_used());
4078 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4079 for (uint i = 0; i < n_queues; i++) {
4080 if (_evacuation_failed_info_array[i].has_failed()) {
4081 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4082 }
4083 }
4084 } else {
4085 // The "used" of the the collection set have already been subtracted
4086 // when they were freed. Add in the bytes evacuated.
4087 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4088 }
4089
4090 if (g1_policy()->during_initial_mark_pause()) {
4091 // We have to do this before we notify the CM threads that
4092 // they can start working to make sure that all the
4093 // appropriate initialization is done on the CM object.
4094 concurrent_mark()->checkpointRootsInitialPost();
4095 set_marking_started();
4096 // Note that we don't actually trigger the CM thread at
4097 // this point. We do that later when we're sure that
4098 // the current thread has completed its logging output.
4099 }
4100
4101 allocate_dummy_regions();
4102
4103 #if YOUNG_LIST_VERBOSE
4104 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4105 _young_list->print();
4106 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4107 #endif // YOUNG_LIST_VERBOSE
4108
4109 _allocator->init_mutator_alloc_region();
4110
4111 {
4112 size_t expand_bytes = g1_policy()->expansion_amount();
4113 if (expand_bytes > 0) {
4114 size_t bytes_before = capacity();
4115 // No need for an ergo verbose message here,
4116 // expansion_amount() does this when it returns a value > 0.
4117 if (!expand(expand_bytes)) {
4118 // We failed to expand the heap. Cannot do anything about it.
4119 }
4120 }
4121 }
4122
4123 // We redo the verification but now wrt to the new CSet which
4124 // has just got initialized after the previous CSet was freed.
4125 _cm->verify_no_cset_oops(true /* verify_stacks */,
4126 true /* verify_enqueued_buffers */,
4127 true /* verify_thread_buffers */,
4128 true /* verify_fingers */);
4129 _cm->note_end_of_gc();
4130
4131 // This timing is only used by the ergonomics to handle our pause target.
4132 // It is unclear why this should not include the full pause. We will
4133 // investigate this in CR 7178365.
4134 double sample_end_time_sec = os::elapsedTime();
4135 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4136 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4137
4138 MemoryService::track_memory_usage();
4139
4140 // In prepare_for_verify() below we'll need to scan the deferred
4141 // update buffers to bring the RSets up-to-date if
4142 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4143 // the update buffers we'll probably need to scan cards on the
4144 // regions we just allocated to (i.e., the GC alloc
4145 // regions). However, during the last GC we called
4146 // set_saved_mark() on all the GC alloc regions, so card
4147 // scanning might skip the [saved_mark_word()...top()] area of
4148 // those regions (i.e., the area we allocated objects into
4149 // during the last GC). But it shouldn't. Given that
4150 // saved_mark_word() is conditional on whether the GC time stamp
4151 // on the region is current or not, by incrementing the GC time
4152 // stamp here we invalidate all the GC time stamps on all the
4153 // regions and saved_mark_word() will simply return top() for
4154 // all the regions. This is a nicer way of ensuring this rather
4155 // than iterating over the regions and fixing them. In fact, the
4156 // GC time stamp increment here also ensures that
4157 // saved_mark_word() will return top() between pauses, i.e.,
4158 // during concurrent refinement. So we don't need the
4159 // is_gc_active() check to decided which top to use when
4160 // scanning cards (see CR 7039627).
4161 increment_gc_time_stamp();
4162
4163 verify_after_gc();
4164 check_bitmaps("GC End");
4165
4166 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4167 ref_processor_stw()->verify_no_references_recorded();
4168
4169 // CM reference discovery will be re-enabled if necessary.
4170 }
4171
4172 // We should do this after we potentially expand the heap so
4173 // that all the COMMIT events are generated before the end GC
4174 // event, and after we retire the GC alloc regions so that all
4175 // RETIRE events are generated before the end GC event.
4176 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4177
4178 #ifdef TRACESPINNING
4179 ParallelTaskTerminator::print_termination_counts();
4180 #endif
4181
4182 gc_epilogue(false);
4183 }
4184
4185 // Print the remainder of the GC log output.
4186 log_gc_footer(os::elapsedTime() - pause_start_sec);
4187
4188 // It is not yet to safe to tell the concurrent mark to
4189 // start as we have some optional output below. We don't want the
4190 // output from the concurrent mark thread interfering with this
4191 // logging output either.
4192
4193 _hrm.verify_optional();
4194 verify_region_sets_optional();
4195
4196 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4197 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4198
4199 print_heap_after_gc();
4200 trace_heap_after_gc(_gc_tracer_stw);
4201
4202 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4203 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4204 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4205 // before any GC notifications are raised.
4206 g1mm()->update_sizes();
4207
4208 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4209 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4210 _gc_timer_stw->register_gc_end();
4211 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4212 }
4213 // It should now be safe to tell the concurrent mark thread to start
4214 // without its logging output interfering with the logging output
4215 // that came from the pause.
4216
4217 if (should_start_conc_mark) {
4218 // CAUTION: after the doConcurrentMark() call below,
4219 // the concurrent marking thread(s) could be running
4220 // concurrently with us. Make sure that anything after
4221 // this point does not assume that we are the only GC thread
4222 // running. Note: of course, the actual marking work will
4223 // not start until the safepoint itself is released in
4224 // SuspendibleThreadSet::desynchronize().
4225 doConcurrentMark();
4226 }
4227
4228 return true;
4229 }
4230
4231 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4232 {
4233 size_t gclab_word_size;
4234 switch (purpose) {
4235 case GCAllocForSurvived:
4236 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4237 break;
4238 case GCAllocForTenured:
4239 gclab_word_size = _old_plab_stats.desired_plab_sz();
4240 break;
4241 default:
4242 assert(false, "unknown GCAllocPurpose");
4243 gclab_word_size = _old_plab_stats.desired_plab_sz();
4244 break;
4245 }
4246
4247 // Prevent humongous PLAB sizes for two reasons:
4248 // * PLABs are allocated using a similar paths as oops, but should
4249 // never be in a humongous region
4250 // * Allowing humongous PLABs needlessly churns the region free lists
4251 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4252 }
4253
4254 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4255 _drain_in_progress = false;
4256 set_evac_failure_closure(cl);
4257 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4258 }
4259
4260 void G1CollectedHeap::finalize_for_evac_failure() {
4261 assert(_evac_failure_scan_stack != NULL &&
4262 _evac_failure_scan_stack->length() == 0,
4263 "Postcondition");
4264 assert(!_drain_in_progress, "Postcondition");
4265 delete _evac_failure_scan_stack;
4266 _evac_failure_scan_stack = NULL;
4267 }
4268
4269 void G1CollectedHeap::remove_self_forwarding_pointers() {
4270 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4271
4272 double remove_self_forwards_start = os::elapsedTime();
4273
4274 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4275
4276 if (G1CollectedHeap::use_parallel_gc_threads()) {
4277 set_par_threads();
4278 workers()->run_task(&rsfp_task);
4279 set_par_threads(0);
4280 } else {
4281 rsfp_task.work(0);
4282 }
4283
4284 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4285
4286 // Reset the claim values in the regions in the collection set.
4287 reset_cset_heap_region_claim_values();
4288
4289 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4290
4291 // Now restore saved marks, if any.
4292 assert(_objs_with_preserved_marks.size() ==
4293 _preserved_marks_of_objs.size(), "Both or none.");
4294 while (!_objs_with_preserved_marks.is_empty()) {
4295 oop obj = _objs_with_preserved_marks.pop();
4296 markOop m = _preserved_marks_of_objs.pop();
4297 obj->set_mark(m);
4298 }
4299 _objs_with_preserved_marks.clear(true);
4300 _preserved_marks_of_objs.clear(true);
4301
4302 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4303 }
4304
4305 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4306 _evac_failure_scan_stack->push(obj);
4307 }
4308
4309 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4310 assert(_evac_failure_scan_stack != NULL, "precondition");
4311
4312 while (_evac_failure_scan_stack->length() > 0) {
4313 oop obj = _evac_failure_scan_stack->pop();
4314 _evac_failure_closure->set_region(heap_region_containing(obj));
4315 obj->oop_iterate_backwards(_evac_failure_closure);
4316 }
4317 }
4318
4319 oop
4320 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4321 oop old) {
4322 assert(obj_in_cs(old),
4323 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4324 (HeapWord*) old));
4325 markOop m = old->mark();
4326 oop forward_ptr = old->forward_to_atomic(old);
4327 if (forward_ptr == NULL) {
4328 // Forward-to-self succeeded.
4329 assert(_par_scan_state != NULL, "par scan state");
4330 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4331 uint queue_num = _par_scan_state->queue_num();
4332
4333 _evacuation_failed = true;
4334 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4335 if (_evac_failure_closure != cl) {
4336 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4337 assert(!_drain_in_progress,
4338 "Should only be true while someone holds the lock.");
4339 // Set the global evac-failure closure to the current thread's.
4340 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4341 set_evac_failure_closure(cl);
4342 // Now do the common part.
4343 handle_evacuation_failure_common(old, m);
4344 // Reset to NULL.
4345 set_evac_failure_closure(NULL);
4346 } else {
4347 // The lock is already held, and this is recursive.
4348 assert(_drain_in_progress, "This should only be the recursive case.");
4349 handle_evacuation_failure_common(old, m);
4350 }
4351 return old;
4352 } else {
4353 // Forward-to-self failed. Either someone else managed to allocate
4354 // space for this object (old != forward_ptr) or they beat us in
4355 // self-forwarding it (old == forward_ptr).
4356 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4357 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4358 "should not be in the CSet",
4359 (HeapWord*) old, (HeapWord*) forward_ptr));
4360 return forward_ptr;
4361 }
4362 }
4363
4364 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4365 preserve_mark_if_necessary(old, m);
4366
4367 HeapRegion* r = heap_region_containing(old);
4368 if (!r->evacuation_failed()) {
4369 r->set_evacuation_failed(true);
4370 _hr_printer.evac_failure(r);
4371 }
4372
4373 push_on_evac_failure_scan_stack(old);
4374
4375 if (!_drain_in_progress) {
4376 // prevent recursion in copy_to_survivor_space()
4377 _drain_in_progress = true;
4378 drain_evac_failure_scan_stack();
4379 _drain_in_progress = false;
4380 }
4381 }
4382
4383 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4384 assert(evacuation_failed(), "Oversaving!");
4385 // We want to call the "for_promotion_failure" version only in the
4386 // case of a promotion failure.
4387 if (m->must_be_preserved_for_promotion_failure(obj)) {
4388 _objs_with_preserved_marks.push(obj);
4389 _preserved_marks_of_objs.push(m);
4390 }
4391 }
4392
4393 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4394 size_t word_size,
4395 AllocationContext_t context) {
4396 if (purpose == GCAllocForSurvived) {
4397 HeapWord* result = survivor_attempt_allocation(word_size, context);
4398 if (result != NULL) {
4399 return result;
4400 } else {
4401 // Let's try to allocate in the old gen in case we can fit the
4402 // object there.
4403 return old_attempt_allocation(word_size, context);
4404 }
4405 } else {
4406 assert(purpose == GCAllocForTenured, "sanity");
4407 HeapWord* result = old_attempt_allocation(word_size, context);
4408 if (result != NULL) {
4409 return result;
4410 } else {
4411 // Let's try to allocate in the survivors in case we can fit the
4412 // object there.
4413 return survivor_attempt_allocation(word_size, context);
4414 }
4415 }
4416
4417 ShouldNotReachHere();
4418 // Trying to keep some compilers happy.
4419 return NULL;
4420 }
4421
4422 void G1ParCopyHelper::mark_object(oop obj) {
4423 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4424
4425 // We know that the object is not moving so it's safe to read its size.
4426 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4427 }
4428
4429 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4430 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4431 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4432 assert(from_obj != to_obj, "should not be self-forwarded");
4433
4434 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4435 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4436
4437 // The object might be in the process of being copied by another
4438 // worker so we cannot trust that its to-space image is
4439 // well-formed. So we have to read its size from its from-space
4440 // image which we know should not be changing.
4441 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4442 }
4443
4444 template <class T>
4445 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4446 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4447 _scanned_klass->record_modified_oops();
4448 }
4449 }
4450
4451 template <G1Barrier barrier, G1Mark do_mark_object>
4452 template <class T>
4453 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4454 T heap_oop = oopDesc::load_heap_oop(p);
4455
4456 if (oopDesc::is_null(heap_oop)) {
4457 return;
4458 }
4459
4460 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4461
4462 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4463
4464 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4465
4466 if (state == G1CollectedHeap::InCSet) {
4467 oop forwardee;
4468 markOop m = obj->mark();
4469 if (m->is_marked()) {
4470 forwardee = (oop) m->decode_pointer();
4471 } else {
4472 forwardee = _par_scan_state->copy_to_survivor_space(obj, m);
4473 }
4474 assert(forwardee != NULL, "forwardee should not be NULL");
4475 oopDesc::encode_store_heap_oop(p, forwardee);
4476 if (do_mark_object != G1MarkNone && forwardee != obj) {
4477 // If the object is self-forwarded we don't need to explicitly
4478 // mark it, the evacuation failure protocol will do so.
4479 mark_forwarded_object(obj, forwardee);
4480 }
4481
4482 if (barrier == G1BarrierKlass) {
4483 do_klass_barrier(p, forwardee);
4484 }
4485 } else {
4486 if (state == G1CollectedHeap::IsHumongous) {
4487 _g1->set_humongous_is_live(obj);
4488 }
4489 // The object is not in collection set. If we're a root scanning
4490 // closure during an initial mark pause then attempt to mark the object.
4491 if (do_mark_object == G1MarkFromRoot) {
4492 mark_object(obj);
4493 }
4494 }
4495
4496 if (barrier == G1BarrierEvac) {
4497 _par_scan_state->update_rs(_from, p, _worker_id);
4498 }
4499 }
4500
4501 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4502 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4503
4504 class G1ParEvacuateFollowersClosure : public VoidClosure {
4505 protected:
4506 G1CollectedHeap* _g1h;
4507 G1ParScanThreadState* _par_scan_state;
4508 RefToScanQueueSet* _queues;
4509 ParallelTaskTerminator* _terminator;
4510
4511 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4512 RefToScanQueueSet* queues() { return _queues; }
4513 ParallelTaskTerminator* terminator() { return _terminator; }
4514
4515 public:
4516 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4517 G1ParScanThreadState* par_scan_state,
4518 RefToScanQueueSet* queues,
4519 ParallelTaskTerminator* terminator)
4520 : _g1h(g1h), _par_scan_state(par_scan_state),
4521 _queues(queues), _terminator(terminator) {}
4522
4523 void do_void();
4524
4525 private:
4526 inline bool offer_termination();
4527 };
4528
4529 bool G1ParEvacuateFollowersClosure::offer_termination() {
4530 G1ParScanThreadState* const pss = par_scan_state();
4531 pss->start_term_time();
4532 const bool res = terminator()->offer_termination();
4533 pss->end_term_time();
4534 return res;
4535 }
4536
4537 void G1ParEvacuateFollowersClosure::do_void() {
4538 G1ParScanThreadState* const pss = par_scan_state();
4539 pss->trim_queue();
4540 do {
4541 pss->steal_and_trim_queue(queues());
4542 } while (!offer_termination());
4543 }
4544
4545 class G1KlassScanClosure : public KlassClosure {
4546 G1ParCopyHelper* _closure;
4547 bool _process_only_dirty;
4548 int _count;
4549 public:
4550 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4551 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4552 void do_klass(Klass* klass) {
4553 // If the klass has not been dirtied we know that there's
4554 // no references into the young gen and we can skip it.
4555 if (!_process_only_dirty || klass->has_modified_oops()) {
4556 // Clean the klass since we're going to scavenge all the metadata.
4557 klass->clear_modified_oops();
4558
4559 // Tell the closure that this klass is the Klass to scavenge
4560 // and is the one to dirty if oops are left pointing into the young gen.
4561 _closure->set_scanned_klass(klass);
4562
4563 klass->oops_do(_closure);
4564
4565 _closure->set_scanned_klass(NULL);
4566 }
4567 _count++;
4568 }
4569 };
4570
4571 class G1ParTask : public AbstractGangTask {
4572 protected:
4573 G1CollectedHeap* _g1h;
4574 RefToScanQueueSet *_queues;
4575 G1RootProcessor* _root_processor;
4576 ParallelTaskTerminator _terminator;
4577 uint _n_workers;
4578
4579 Mutex _stats_lock;
4580 Mutex* stats_lock() { return &_stats_lock; }
4581
4582 public:
4583 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4584 : AbstractGangTask("G1 collection"),
4585 _g1h(g1h),
4586 _queues(task_queues),
4587 _root_processor(root_processor),
4588 _terminator(0, _queues),
4589 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4590 {}
4591
4592 RefToScanQueueSet* queues() { return _queues; }
4593
4594 RefToScanQueue *work_queue(int i) {
4595 return queues()->queue(i);
4596 }
4597
4598 ParallelTaskTerminator* terminator() { return &_terminator; }
4599
4600 virtual void set_for_termination(int active_workers) {
4601 _root_processor->set_num_workers(active_workers);
4602 terminator()->reset_for_reuse(active_workers);
4603 _n_workers = active_workers;
4604 }
4605
4606 // Helps out with CLD processing.
4607 //
4608 // During InitialMark we need to:
4609 // 1) Scavenge all CLDs for the young GC.
4610 // 2) Mark all objects directly reachable from strong CLDs.
4611 template <G1Mark do_mark_object>
4612 class G1CLDClosure : public CLDClosure {
4613 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4614 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4615 G1KlassScanClosure _klass_in_cld_closure;
4616 bool _claim;
4617
4618 public:
4619 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4620 bool only_young, bool claim)
4621 : _oop_closure(oop_closure),
4622 _oop_in_klass_closure(oop_closure->g1(),
4623 oop_closure->pss(),
4624 oop_closure->rp()),
4625 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4626 _claim(claim) {
4627
4628 }
4629
4630 void do_cld(ClassLoaderData* cld) {
4631 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4632 }
4633 };
4634
4635 void work(uint worker_id) {
4636 if (worker_id >= _n_workers) return; // no work needed this round
4637
4638 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4639
4640 {
4641 ResourceMark rm;
4642 HandleMark hm;
4643
4644 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4645
4646 G1ParScanThreadState pss(_g1h, worker_id, rp);
4647 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4648
4649 pss.set_evac_failure_closure(&evac_failure_cl);
4650
4651 bool only_young = _g1h->g1_policy()->gcs_are_young();
4652
4653 // Non-IM young GC.
4654 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4655 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4656 only_young, // Only process dirty klasses.
4657 false); // No need to claim CLDs.
4658 // IM young GC.
4659 // Strong roots closures.
4660 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4661 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4662 false, // Process all klasses.
4663 true); // Need to claim CLDs.
4664 // Weak roots closures.
4665 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4666 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4667 false, // Process all klasses.
4668 true); // Need to claim CLDs.
4669
4670 OopClosure* strong_root_cl;
4671 OopClosure* weak_root_cl;
4672 CLDClosure* strong_cld_cl;
4673 CLDClosure* weak_cld_cl;
4674
4675 bool trace_metadata = false;
4676
4677 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4678 // We also need to mark copied objects.
4679 strong_root_cl = &scan_mark_root_cl;
4680 strong_cld_cl = &scan_mark_cld_cl;
4681 if (ClassUnloadingWithConcurrentMark) {
4682 weak_root_cl = &scan_mark_weak_root_cl;
4683 weak_cld_cl = &scan_mark_weak_cld_cl;
4684 trace_metadata = true;
4685 } else {
4686 weak_root_cl = &scan_mark_root_cl;
4687 weak_cld_cl = &scan_mark_cld_cl;
4688 }
4689 } else {
4690 strong_root_cl = &scan_only_root_cl;
4691 weak_root_cl = &scan_only_root_cl;
4692 strong_cld_cl = &scan_only_cld_cl;
4693 weak_cld_cl = &scan_only_cld_cl;
4694 }
4695
4696 pss.start_strong_roots();
4697
4698 _root_processor->evacuate_roots(strong_root_cl,
4699 weak_root_cl,
4700 strong_cld_cl,
4701 weak_cld_cl,
4702 trace_metadata,
4703 worker_id);
4704
4705 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4706 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4707 weak_root_cl,
4708 worker_id);
4709 pss.end_strong_roots();
4710
4711 {
4712 double start = os::elapsedTime();
4713 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4714 evac.do_void();
4715 double elapsed_sec = os::elapsedTime() - start;
4716 double term_sec = pss.term_time();
4717 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4718 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4719 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4720 }
4721 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4722 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4723
4724 if (ParallelGCVerbose) {
4725 MutexLocker x(stats_lock());
4726 pss.print_termination_stats(worker_id);
4727 }
4728
4729 assert(pss.queue_is_empty(), "should be empty");
4730
4731 // Close the inner scope so that the ResourceMark and HandleMark
4732 // destructors are executed here and are included as part of the
4733 // "GC Worker Time".
4734 }
4735 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4736 }
4737 };
4738
4739 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4740 private:
4741 BoolObjectClosure* _is_alive;
4742 int _initial_string_table_size;
4743 int _initial_symbol_table_size;
4744
4745 bool _process_strings;
4746 int _strings_processed;
4747 int _strings_removed;
4748
4749 bool _process_symbols;
4750 int _symbols_processed;
4751 int _symbols_removed;
4752
4753 bool _do_in_parallel;
4754 public:
4755 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4756 AbstractGangTask("String/Symbol Unlinking"),
4757 _is_alive(is_alive),
4758 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4759 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4760 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4761
4762 _initial_string_table_size = StringTable::the_table()->table_size();
4763 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4764 if (process_strings) {
4765 StringTable::clear_parallel_claimed_index();
4766 }
4767 if (process_symbols) {
4768 SymbolTable::clear_parallel_claimed_index();
4769 }
4770 }
4771
4772 ~G1StringSymbolTableUnlinkTask() {
4773 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4774 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4775 StringTable::parallel_claimed_index(), _initial_string_table_size));
4776 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4777 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4778 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4779
4780 if (G1TraceStringSymbolTableScrubbing) {
4781 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4782 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4783 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4784 strings_processed(), strings_removed(),
4785 symbols_processed(), symbols_removed());
4786 }
4787 }
4788
4789 void work(uint worker_id) {
4790 if (_do_in_parallel) {
4791 int strings_processed = 0;
4792 int strings_removed = 0;
4793 int symbols_processed = 0;
4794 int symbols_removed = 0;
4795 if (_process_strings) {
4796 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4797 Atomic::add(strings_processed, &_strings_processed);
4798 Atomic::add(strings_removed, &_strings_removed);
4799 }
4800 if (_process_symbols) {
4801 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4802 Atomic::add(symbols_processed, &_symbols_processed);
4803 Atomic::add(symbols_removed, &_symbols_removed);
4804 }
4805 } else {
4806 if (_process_strings) {
4807 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
4808 }
4809 if (_process_symbols) {
4810 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
4811 }
4812 }
4813 }
4814
4815 size_t strings_processed() const { return (size_t)_strings_processed; }
4816 size_t strings_removed() const { return (size_t)_strings_removed; }
4817
4818 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4819 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4820 };
4821
4822 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4823 private:
4824 static Monitor* _lock;
4825
4826 BoolObjectClosure* const _is_alive;
4827 const bool _unloading_occurred;
4828 const uint _num_workers;
4829
4830 // Variables used to claim nmethods.
4831 nmethod* _first_nmethod;
4832 volatile nmethod* _claimed_nmethod;
4833
4834 // The list of nmethods that need to be processed by the second pass.
4835 volatile nmethod* _postponed_list;
4836 volatile uint _num_entered_barrier;
4837
4838 public:
4839 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4840 _is_alive(is_alive),
4841 _unloading_occurred(unloading_occurred),
4842 _num_workers(num_workers),
4843 _first_nmethod(NULL),
4844 _claimed_nmethod(NULL),
4845 _postponed_list(NULL),
4846 _num_entered_barrier(0)
4847 {
4848 nmethod::increase_unloading_clock();
4849 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
4850 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4851 }
4852
4853 ~G1CodeCacheUnloadingTask() {
4854 CodeCache::verify_clean_inline_caches();
4855
4856 CodeCache::set_needs_cache_clean(false);
4857 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4858
4859 CodeCache::verify_icholder_relocations();
4860 }
4861
4862 private:
4863 void add_to_postponed_list(nmethod* nm) {
4864 nmethod* old;
4865 do {
4866 old = (nmethod*)_postponed_list;
4867 nm->set_unloading_next(old);
4868 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4869 }
4870
4871 void clean_nmethod(nmethod* nm) {
4872 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4873
4874 if (postponed) {
4875 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4876 add_to_postponed_list(nm);
4877 }
4878
4879 // Mark that this thread has been cleaned/unloaded.
4880 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4881 nm->set_unloading_clock(nmethod::global_unloading_clock());
4882 }
4883
4884 void clean_nmethod_postponed(nmethod* nm) {
4885 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4886 }
4887
4888 static const int MaxClaimNmethods = 16;
4889
4890 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4891 nmethod* first;
4892 nmethod* last;
4893
4894 do {
4895 *num_claimed_nmethods = 0;
4896
4897 first = last = (nmethod*)_claimed_nmethod;
4898
4899 if (first != NULL) {
4900 for (int i = 0; i < MaxClaimNmethods; i++) {
4901 last = CodeCache::alive_nmethod(CodeCache::next(last));
4902
4903 if (last == NULL) {
4904 break;
4905 }
4906
4907 claimed_nmethods[i] = last;
4908 (*num_claimed_nmethods)++;
4909 }
4910 }
4911
4912 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
4913 }
4914
4915 nmethod* claim_postponed_nmethod() {
4916 nmethod* claim;
4917 nmethod* next;
4918
4919 do {
4920 claim = (nmethod*)_postponed_list;
4921 if (claim == NULL) {
4922 return NULL;
4923 }
4924
4925 next = claim->unloading_next();
4926
4927 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4928
4929 return claim;
4930 }
4931
4932 public:
4933 // Mark that we're done with the first pass of nmethod cleaning.
4934 void barrier_mark(uint worker_id) {
4935 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4936 _num_entered_barrier++;
4937 if (_num_entered_barrier == _num_workers) {
4938 ml.notify_all();
4939 }
4940 }
4941
4942 // See if we have to wait for the other workers to
4943 // finish their first-pass nmethod cleaning work.
4944 void barrier_wait(uint worker_id) {
4945 if (_num_entered_barrier < _num_workers) {
4946 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4947 while (_num_entered_barrier < _num_workers) {
4948 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4949 }
4950 }
4951 }
4952
4953 // Cleaning and unloading of nmethods. Some work has to be postponed
4954 // to the second pass, when we know which nmethods survive.
4955 void work_first_pass(uint worker_id) {
4956 // The first nmethods is claimed by the first worker.
4957 if (worker_id == 0 && _first_nmethod != NULL) {
4958 clean_nmethod(_first_nmethod);
4959 _first_nmethod = NULL;
4960 }
4961
4962 int num_claimed_nmethods;
4963 nmethod* claimed_nmethods[MaxClaimNmethods];
4964
4965 while (true) {
4966 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4967
4968 if (num_claimed_nmethods == 0) {
4969 break;
4970 }
4971
4972 for (int i = 0; i < num_claimed_nmethods; i++) {
4973 clean_nmethod(claimed_nmethods[i]);
4974 }
4975 }
4976
4977 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4978 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4979 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4980 }
4981
4982 void work_second_pass(uint worker_id) {
4983 nmethod* nm;
4984 // Take care of postponed nmethods.
4985 while ((nm = claim_postponed_nmethod()) != NULL) {
4986 clean_nmethod_postponed(nm);
4987 }
4988 }
4989 };
4990
4991 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
4992
4993 class G1KlassCleaningTask : public StackObj {
4994 BoolObjectClosure* _is_alive;
4995 volatile jint _clean_klass_tree_claimed;
4996 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4997
4998 public:
4999 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5000 _is_alive(is_alive),
5001 _clean_klass_tree_claimed(0),
5002 _klass_iterator() {
5003 }
5004
5005 private:
5006 bool claim_clean_klass_tree_task() {
5007 if (_clean_klass_tree_claimed) {
5008 return false;
5009 }
5010
5011 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5012 }
5013
5014 InstanceKlass* claim_next_klass() {
5015 Klass* klass;
5016 do {
5017 klass =_klass_iterator.next_klass();
5018 } while (klass != NULL && !klass->oop_is_instance());
5019
5020 return (InstanceKlass*)klass;
5021 }
5022
5023 public:
5024
5025 void clean_klass(InstanceKlass* ik) {
5026 ik->clean_implementors_list(_is_alive);
5027 ik->clean_method_data(_is_alive);
5028
5029 // G1 specific cleanup work that has
5030 // been moved here to be done in parallel.
5031 ik->clean_dependent_nmethods();
5032 if (JvmtiExport::has_redefined_a_class()) {
5033 InstanceKlass::purge_previous_versions(ik);
5034 }
5035 }
5036
5037 void work() {
5038 ResourceMark rm;
5039
5040 // One worker will clean the subklass/sibling klass tree.
5041 if (claim_clean_klass_tree_task()) {
5042 Klass::clean_subklass_tree(_is_alive);
5043 }
5044
5045 // All workers will help cleaning the classes,
5046 InstanceKlass* klass;
5047 while ((klass = claim_next_klass()) != NULL) {
5048 clean_klass(klass);
5049 }
5050 }
5051 };
5052
5053 // To minimize the remark pause times, the tasks below are done in parallel.
5054 class G1ParallelCleaningTask : public AbstractGangTask {
5055 private:
5056 G1StringSymbolTableUnlinkTask _string_symbol_task;
5057 G1CodeCacheUnloadingTask _code_cache_task;
5058 G1KlassCleaningTask _klass_cleaning_task;
5059
5060 public:
5061 // The constructor is run in the VMThread.
5062 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5063 AbstractGangTask("Parallel Cleaning"),
5064 _string_symbol_task(is_alive, process_strings, process_symbols),
5065 _code_cache_task(num_workers, is_alive, unloading_occurred),
5066 _klass_cleaning_task(is_alive) {
5067 }
5068
5069 void pre_work_verification() {
5070 // The VM Thread will have registered Metadata during the single-threaded phase of MetadataStackOnMark.
5071 assert(Thread::current()->is_VM_thread()
5072 || !MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5073 }
5074
5075 void post_work_verification() {
5076 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5077 }
5078
5079 // The parallel work done by all worker threads.
5080 void work(uint worker_id) {
5081 pre_work_verification();
5082
5083 // Do first pass of code cache cleaning.
5084 _code_cache_task.work_first_pass(worker_id);
5085
5086 // Let the threads mark that the first pass is done.
5087 _code_cache_task.barrier_mark(worker_id);
5088
5089 // Clean the Strings and Symbols.
5090 _string_symbol_task.work(worker_id);
5091
5092 // Wait for all workers to finish the first code cache cleaning pass.
5093 _code_cache_task.barrier_wait(worker_id);
5094
5095 // Do the second code cache cleaning work, which realize on
5096 // the liveness information gathered during the first pass.
5097 _code_cache_task.work_second_pass(worker_id);
5098
5099 // Clean all klasses that were not unloaded.
5100 _klass_cleaning_task.work();
5101
5102 post_work_verification();
5103 }
5104 };
5105
5106
5107 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5108 bool process_strings,
5109 bool process_symbols,
5110 bool class_unloading_occurred) {
5111 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5112 workers()->active_workers() : 1);
5113
5114 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5115 n_workers, class_unloading_occurred);
5116 if (G1CollectedHeap::use_parallel_gc_threads()) {
5117 set_par_threads(n_workers);
5118 workers()->run_task(&g1_unlink_task);
5119 set_par_threads(0);
5120 } else {
5121 g1_unlink_task.work(0);
5122 }
5123 }
5124
5125 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5126 bool process_strings, bool process_symbols) {
5127 {
5128 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5129 _g1h->workers()->active_workers() : 1);
5130 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5131 if (G1CollectedHeap::use_parallel_gc_threads()) {
5132 set_par_threads(n_workers);
5133 workers()->run_task(&g1_unlink_task);
5134 set_par_threads(0);
5135 } else {
5136 g1_unlink_task.work(0);
5137 }
5138 }
5139
5140 if (G1StringDedup::is_enabled()) {
5141 G1StringDedup::unlink(is_alive);
5142 }
5143 }
5144
5145 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5146 private:
5147 DirtyCardQueueSet* _queue;
5148 public:
5149 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5150
5151 virtual void work(uint worker_id) {
5152 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5153 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5154
5155 RedirtyLoggedCardTableEntryClosure cl;
5156 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5157 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5158 } else {
5159 _queue->apply_closure_to_all_completed_buffers(&cl);
5160 }
5161
5162 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5163 }
5164 };
5165
5166 void G1CollectedHeap::redirty_logged_cards() {
5167 double redirty_logged_cards_start = os::elapsedTime();
5168
5169 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5170 _g1h->workers()->active_workers() : 1);
5171
5172 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5173 dirty_card_queue_set().reset_for_par_iteration();
5174 if (use_parallel_gc_threads()) {
5175 set_par_threads(n_workers);
5176 workers()->run_task(&redirty_task);
5177 set_par_threads(0);
5178 } else {
5179 redirty_task.work(0);
5180 }
5181
5182 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5183 dcq.merge_bufferlists(&dirty_card_queue_set());
5184 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5185
5186 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5187 }
5188
5189 // Weak Reference Processing support
5190
5191 // An always "is_alive" closure that is used to preserve referents.
5192 // If the object is non-null then it's alive. Used in the preservation
5193 // of referent objects that are pointed to by reference objects
5194 // discovered by the CM ref processor.
5195 class G1AlwaysAliveClosure: public BoolObjectClosure {
5196 G1CollectedHeap* _g1;
5197 public:
5198 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5199 bool do_object_b(oop p) {
5200 if (p != NULL) {
5201 return true;
5202 }
5203 return false;
5204 }
5205 };
5206
5207 bool G1STWIsAliveClosure::do_object_b(oop p) {
5208 // An object is reachable if it is outside the collection set,
5209 // or is inside and copied.
5210 return !_g1->obj_in_cs(p) || p->is_forwarded();
5211 }
5212
5213 // Non Copying Keep Alive closure
5214 class G1KeepAliveClosure: public OopClosure {
5215 G1CollectedHeap* _g1;
5216 public:
5217 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5218 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5219 void do_oop(oop* p) {
5220 oop obj = *p;
5221 assert(obj != NULL, "the caller should have filtered out NULL values");
5222
5223 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5224 if (cset_state == G1CollectedHeap::InNeither) {
5225 return;
5226 }
5227 if (cset_state == G1CollectedHeap::InCSet) {
5228 assert( obj->is_forwarded(), "invariant" );
5229 *p = obj->forwardee();
5230 } else {
5231 assert(!obj->is_forwarded(), "invariant" );
5232 assert(cset_state == G1CollectedHeap::IsHumongous,
5233 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5234 _g1->set_humongous_is_live(obj);
5235 }
5236 }
5237 };
5238
5239 // Copying Keep Alive closure - can be called from both
5240 // serial and parallel code as long as different worker
5241 // threads utilize different G1ParScanThreadState instances
5242 // and different queues.
5243
5244 class G1CopyingKeepAliveClosure: public OopClosure {
5245 G1CollectedHeap* _g1h;
5246 OopClosure* _copy_non_heap_obj_cl;
5247 G1ParScanThreadState* _par_scan_state;
5248
5249 public:
5250 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5251 OopClosure* non_heap_obj_cl,
5252 G1ParScanThreadState* pss):
5253 _g1h(g1h),
5254 _copy_non_heap_obj_cl(non_heap_obj_cl),
5255 _par_scan_state(pss)
5256 {}
5257
5258 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5259 virtual void do_oop( oop* p) { do_oop_work(p); }
5260
5261 template <class T> void do_oop_work(T* p) {
5262 oop obj = oopDesc::load_decode_heap_oop(p);
5263
5264 if (_g1h->is_in_cset_or_humongous(obj)) {
5265 // If the referent object has been forwarded (either copied
5266 // to a new location or to itself in the event of an
5267 // evacuation failure) then we need to update the reference
5268 // field and, if both reference and referent are in the G1
5269 // heap, update the RSet for the referent.
5270 //
5271 // If the referent has not been forwarded then we have to keep
5272 // it alive by policy. Therefore we have copy the referent.
5273 //
5274 // If the reference field is in the G1 heap then we can push
5275 // on the PSS queue. When the queue is drained (after each
5276 // phase of reference processing) the object and it's followers
5277 // will be copied, the reference field set to point to the
5278 // new location, and the RSet updated. Otherwise we need to
5279 // use the the non-heap or metadata closures directly to copy
5280 // the referent object and update the pointer, while avoiding
5281 // updating the RSet.
5282
5283 if (_g1h->is_in_g1_reserved(p)) {
5284 _par_scan_state->push_on_queue(p);
5285 } else {
5286 assert(!Metaspace::contains((const void*)p),
5287 err_msg("Unexpectedly found a pointer from metadata: "
5288 PTR_FORMAT, p));
5289 _copy_non_heap_obj_cl->do_oop(p);
5290 }
5291 }
5292 }
5293 };
5294
5295 // Serial drain queue closure. Called as the 'complete_gc'
5296 // closure for each discovered list in some of the
5297 // reference processing phases.
5298
5299 class G1STWDrainQueueClosure: public VoidClosure {
5300 protected:
5301 G1CollectedHeap* _g1h;
5302 G1ParScanThreadState* _par_scan_state;
5303
5304 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5305
5306 public:
5307 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5308 _g1h(g1h),
5309 _par_scan_state(pss)
5310 { }
5311
5312 void do_void() {
5313 G1ParScanThreadState* const pss = par_scan_state();
5314 pss->trim_queue();
5315 }
5316 };
5317
5318 // Parallel Reference Processing closures
5319
5320 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5321 // processing during G1 evacuation pauses.
5322
5323 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5324 private:
5325 G1CollectedHeap* _g1h;
5326 RefToScanQueueSet* _queues;
5327 FlexibleWorkGang* _workers;
5328 int _active_workers;
5329
5330 public:
5331 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5332 FlexibleWorkGang* workers,
5333 RefToScanQueueSet *task_queues,
5334 int n_workers) :
5335 _g1h(g1h),
5336 _queues(task_queues),
5337 _workers(workers),
5338 _active_workers(n_workers)
5339 {
5340 assert(n_workers > 0, "shouldn't call this otherwise");
5341 }
5342
5343 // Executes the given task using concurrent marking worker threads.
5344 virtual void execute(ProcessTask& task);
5345 virtual void execute(EnqueueTask& task);
5346 };
5347
5348 // Gang task for possibly parallel reference processing
5349
5350 class G1STWRefProcTaskProxy: public AbstractGangTask {
5351 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5352 ProcessTask& _proc_task;
5353 G1CollectedHeap* _g1h;
5354 RefToScanQueueSet *_task_queues;
5355 ParallelTaskTerminator* _terminator;
5356
5357 public:
5358 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5359 G1CollectedHeap* g1h,
5360 RefToScanQueueSet *task_queues,
5361 ParallelTaskTerminator* terminator) :
5362 AbstractGangTask("Process reference objects in parallel"),
5363 _proc_task(proc_task),
5364 _g1h(g1h),
5365 _task_queues(task_queues),
5366 _terminator(terminator)
5367 {}
5368
5369 virtual void work(uint worker_id) {
5370 // The reference processing task executed by a single worker.
5371 ResourceMark rm;
5372 HandleMark hm;
5373
5374 G1STWIsAliveClosure is_alive(_g1h);
5375
5376 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5377 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5378
5379 pss.set_evac_failure_closure(&evac_failure_cl);
5380
5381 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5382
5383 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5384
5385 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5386
5387 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5388 // We also need to mark copied objects.
5389 copy_non_heap_cl = ©_mark_non_heap_cl;
5390 }
5391
5392 // Keep alive closure.
5393 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5394
5395 // Complete GC closure
5396 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5397
5398 // Call the reference processing task's work routine.
5399 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5400
5401 // Note we cannot assert that the refs array is empty here as not all
5402 // of the processing tasks (specifically phase2 - pp2_work) execute
5403 // the complete_gc closure (which ordinarily would drain the queue) so
5404 // the queue may not be empty.
5405 }
5406 };
5407
5408 // Driver routine for parallel reference processing.
5409 // Creates an instance of the ref processing gang
5410 // task and has the worker threads execute it.
5411 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5412 assert(_workers != NULL, "Need parallel worker threads.");
5413
5414 ParallelTaskTerminator terminator(_active_workers, _queues);
5415 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5416
5417 _g1h->set_par_threads(_active_workers);
5418 _workers->run_task(&proc_task_proxy);
5419 _g1h->set_par_threads(0);
5420 }
5421
5422 // Gang task for parallel reference enqueueing.
5423
5424 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5425 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5426 EnqueueTask& _enq_task;
5427
5428 public:
5429 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5430 AbstractGangTask("Enqueue reference objects in parallel"),
5431 _enq_task(enq_task)
5432 { }
5433
5434 virtual void work(uint worker_id) {
5435 _enq_task.work(worker_id);
5436 }
5437 };
5438
5439 // Driver routine for parallel reference enqueueing.
5440 // Creates an instance of the ref enqueueing gang
5441 // task and has the worker threads execute it.
5442
5443 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5444 assert(_workers != NULL, "Need parallel worker threads.");
5445
5446 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5447
5448 _g1h->set_par_threads(_active_workers);
5449 _workers->run_task(&enq_task_proxy);
5450 _g1h->set_par_threads(0);
5451 }
5452
5453 // End of weak reference support closures
5454
5455 // Abstract task used to preserve (i.e. copy) any referent objects
5456 // that are in the collection set and are pointed to by reference
5457 // objects discovered by the CM ref processor.
5458
5459 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5460 protected:
5461 G1CollectedHeap* _g1h;
5462 RefToScanQueueSet *_queues;
5463 ParallelTaskTerminator _terminator;
5464 uint _n_workers;
5465
5466 public:
5467 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5468 AbstractGangTask("ParPreserveCMReferents"),
5469 _g1h(g1h),
5470 _queues(task_queues),
5471 _terminator(workers, _queues),
5472 _n_workers(workers)
5473 { }
5474
5475 void work(uint worker_id) {
5476 ResourceMark rm;
5477 HandleMark hm;
5478
5479 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5480 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5481
5482 pss.set_evac_failure_closure(&evac_failure_cl);
5483
5484 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5485
5486 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5487
5488 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5489
5490 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5491
5492 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5493 // We also need to mark copied objects.
5494 copy_non_heap_cl = ©_mark_non_heap_cl;
5495 }
5496
5497 // Is alive closure
5498 G1AlwaysAliveClosure always_alive(_g1h);
5499
5500 // Copying keep alive closure. Applied to referent objects that need
5501 // to be copied.
5502 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5503
5504 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5505
5506 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5507 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5508
5509 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5510 // So this must be true - but assert just in case someone decides to
5511 // change the worker ids.
5512 assert(0 <= worker_id && worker_id < limit, "sanity");
5513 assert(!rp->discovery_is_atomic(), "check this code");
5514
5515 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5516 for (uint idx = worker_id; idx < limit; idx += stride) {
5517 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5518
5519 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5520 while (iter.has_next()) {
5521 // Since discovery is not atomic for the CM ref processor, we
5522 // can see some null referent objects.
5523 iter.load_ptrs(DEBUG_ONLY(true));
5524 oop ref = iter.obj();
5525
5526 // This will filter nulls.
5527 if (iter.is_referent_alive()) {
5528 iter.make_referent_alive();
5529 }
5530 iter.move_to_next();
5531 }
5532 }
5533
5534 // Drain the queue - which may cause stealing
5535 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5536 drain_queue.do_void();
5537 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5538 assert(pss.queue_is_empty(), "should be");
5539 }
5540 };
5541
5542 // Weak Reference processing during an evacuation pause (part 1).
5543 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5544 double ref_proc_start = os::elapsedTime();
5545
5546 ReferenceProcessor* rp = _ref_processor_stw;
5547 assert(rp->discovery_enabled(), "should have been enabled");
5548
5549 // Any reference objects, in the collection set, that were 'discovered'
5550 // by the CM ref processor should have already been copied (either by
5551 // applying the external root copy closure to the discovered lists, or
5552 // by following an RSet entry).
5553 //
5554 // But some of the referents, that are in the collection set, that these
5555 // reference objects point to may not have been copied: the STW ref
5556 // processor would have seen that the reference object had already
5557 // been 'discovered' and would have skipped discovering the reference,
5558 // but would not have treated the reference object as a regular oop.
5559 // As a result the copy closure would not have been applied to the
5560 // referent object.
5561 //
5562 // We need to explicitly copy these referent objects - the references
5563 // will be processed at the end of remarking.
5564 //
5565 // We also need to do this copying before we process the reference
5566 // objects discovered by the STW ref processor in case one of these
5567 // referents points to another object which is also referenced by an
5568 // object discovered by the STW ref processor.
5569
5570 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5571 no_of_gc_workers == workers()->active_workers(),
5572 "Need to reset active GC workers");
5573
5574 set_par_threads(no_of_gc_workers);
5575 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5576 no_of_gc_workers,
5577 _task_queues);
5578
5579 if (G1CollectedHeap::use_parallel_gc_threads()) {
5580 workers()->run_task(&keep_cm_referents);
5581 } else {
5582 keep_cm_referents.work(0);
5583 }
5584
5585 set_par_threads(0);
5586
5587 // Closure to test whether a referent is alive.
5588 G1STWIsAliveClosure is_alive(this);
5589
5590 // Even when parallel reference processing is enabled, the processing
5591 // of JNI refs is serial and performed serially by the current thread
5592 // rather than by a worker. The following PSS will be used for processing
5593 // JNI refs.
5594
5595 // Use only a single queue for this PSS.
5596 G1ParScanThreadState pss(this, 0, NULL);
5597
5598 // We do not embed a reference processor in the copying/scanning
5599 // closures while we're actually processing the discovered
5600 // reference objects.
5601 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5602
5603 pss.set_evac_failure_closure(&evac_failure_cl);
5604
5605 assert(pss.queue_is_empty(), "pre-condition");
5606
5607 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5608
5609 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5610
5611 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5612
5613 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5614 // We also need to mark copied objects.
5615 copy_non_heap_cl = ©_mark_non_heap_cl;
5616 }
5617
5618 // Keep alive closure.
5619 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5620
5621 // Serial Complete GC closure
5622 G1STWDrainQueueClosure drain_queue(this, &pss);
5623
5624 // Setup the soft refs policy...
5625 rp->setup_policy(false);
5626
5627 ReferenceProcessorStats stats;
5628 if (!rp->processing_is_mt()) {
5629 // Serial reference processing...
5630 stats = rp->process_discovered_references(&is_alive,
5631 &keep_alive,
5632 &drain_queue,
5633 NULL,
5634 _gc_timer_stw,
5635 _gc_tracer_stw->gc_id());
5636 } else {
5637 // Parallel reference processing
5638 assert(rp->num_q() == no_of_gc_workers, "sanity");
5639 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5640
5641 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5642 stats = rp->process_discovered_references(&is_alive,
5643 &keep_alive,
5644 &drain_queue,
5645 &par_task_executor,
5646 _gc_timer_stw,
5647 _gc_tracer_stw->gc_id());
5648 }
5649
5650 _gc_tracer_stw->report_gc_reference_stats(stats);
5651
5652 // We have completed copying any necessary live referent objects.
5653 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5654
5655 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5656 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5657 }
5658
5659 // Weak Reference processing during an evacuation pause (part 2).
5660 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5661 double ref_enq_start = os::elapsedTime();
5662
5663 ReferenceProcessor* rp = _ref_processor_stw;
5664 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5665
5666 // Now enqueue any remaining on the discovered lists on to
5667 // the pending list.
5668 if (!rp->processing_is_mt()) {
5669 // Serial reference processing...
5670 rp->enqueue_discovered_references();
5671 } else {
5672 // Parallel reference enqueueing
5673
5674 assert(no_of_gc_workers == workers()->active_workers(),
5675 "Need to reset active workers");
5676 assert(rp->num_q() == no_of_gc_workers, "sanity");
5677 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5678
5679 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5680 rp->enqueue_discovered_references(&par_task_executor);
5681 }
5682
5683 rp->verify_no_references_recorded();
5684 assert(!rp->discovery_enabled(), "should have been disabled");
5685
5686 // FIXME
5687 // CM's reference processing also cleans up the string and symbol tables.
5688 // Should we do that here also? We could, but it is a serial operation
5689 // and could significantly increase the pause time.
5690
5691 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5692 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5693 }
5694
5695 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5696 _expand_heap_after_alloc_failure = true;
5697 _evacuation_failed = false;
5698
5699 // Should G1EvacuationFailureALot be in effect for this GC?
5700 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5701
5702 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5703
5704 // Disable the hot card cache.
5705 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5706 hot_card_cache->reset_hot_cache_claimed_index();
5707 hot_card_cache->set_use_cache(false);
5708
5709 uint n_workers;
5710 if (G1CollectedHeap::use_parallel_gc_threads()) {
5711 n_workers =
5712 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5713 workers()->active_workers(),
5714 Threads::number_of_non_daemon_threads());
5715 assert(UseDynamicNumberOfGCThreads ||
5716 n_workers == workers()->total_workers(),
5717 "If not dynamic should be using all the workers");
5718 workers()->set_active_workers(n_workers);
5719 set_par_threads(n_workers);
5720 } else {
5721 assert(n_par_threads() == 0,
5722 "Should be the original non-parallel value");
5723 n_workers = 1;
5724 }
5725
5726
5727 init_for_evac_failure(NULL);
5728
5729 rem_set()->prepare_for_younger_refs_iterate(true);
5730
5731 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5732 double start_par_time_sec = os::elapsedTime();
5733 double end_par_time_sec;
5734
5735 {
5736 G1RootProcessor root_processor(this);
5737 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5738 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5739 if (g1_policy()->during_initial_mark_pause()) {
5740 ClassLoaderDataGraph::clear_claimed_marks();
5741 }
5742
5743 if (G1CollectedHeap::use_parallel_gc_threads()) {
5744 // The individual threads will set their evac-failure closures.
5745 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5746 // These tasks use ShareHeap::_process_strong_tasks
5747 assert(UseDynamicNumberOfGCThreads ||
5748 workers()->active_workers() == workers()->total_workers(),
5749 "If not dynamic should be using all the workers");
5750 workers()->run_task(&g1_par_task);
5751 } else {
5752 g1_par_task.set_for_termination(n_workers);
5753 g1_par_task.work(0);
5754 }
5755 end_par_time_sec = os::elapsedTime();
5756
5757 // Closing the inner scope will execute the destructor
5758 // for the G1RootProcessor object. We record the current
5759 // elapsed time before closing the scope so that time
5760 // taken for the destructor is NOT included in the
5761 // reported parallel time.
5762 }
5763
5764 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5765
5766 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5767 phase_times->record_par_time(par_time_ms);
5768
5769 double code_root_fixup_time_ms =
5770 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5771 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5772
5773 set_par_threads(0);
5774
5775 // Process any discovered reference objects - we have
5776 // to do this _before_ we retire the GC alloc regions
5777 // as we may have to copy some 'reachable' referent
5778 // objects (and their reachable sub-graphs) that were
5779 // not copied during the pause.
5780 process_discovered_references(n_workers);
5781
5782 if (G1StringDedup::is_enabled()) {
5783 double fixup_start = os::elapsedTime();
5784
5785 G1STWIsAliveClosure is_alive(this);
5786 G1KeepAliveClosure keep_alive(this);
5787 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5788
5789 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5790 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5791 }
5792
5793 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5794 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5795
5796 // Reset and re-enable the hot card cache.
5797 // Note the counts for the cards in the regions in the
5798 // collection set are reset when the collection set is freed.
5799 hot_card_cache->reset_hot_cache();
5800 hot_card_cache->set_use_cache(true);
5801
5802 purge_code_root_memory();
5803
5804 if (g1_policy()->during_initial_mark_pause()) {
5805 // Reset the claim values set during marking the strong code roots
5806 reset_heap_region_claim_values();
5807 }
5808
5809 finalize_for_evac_failure();
5810
5811 if (evacuation_failed()) {
5812 remove_self_forwarding_pointers();
5813
5814 // Reset the G1EvacuationFailureALot counters and flags
5815 // Note: the values are reset only when an actual
5816 // evacuation failure occurs.
5817 NOT_PRODUCT(reset_evacuation_should_fail();)
5818 }
5819
5820 // Enqueue any remaining references remaining on the STW
5821 // reference processor's discovered lists. We need to do
5822 // this after the card table is cleaned (and verified) as
5823 // the act of enqueueing entries on to the pending list
5824 // will log these updates (and dirty their associated
5825 // cards). We need these updates logged to update any
5826 // RSets.
5827 enqueue_discovered_references(n_workers);
5828
5829 redirty_logged_cards();
5830 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5831 }
5832
5833 void G1CollectedHeap::free_region(HeapRegion* hr,
5834 FreeRegionList* free_list,
5835 bool par,
5836 bool locked) {
5837 assert(!hr->is_free(), "the region should not be free");
5838 assert(!hr->is_empty(), "the region should not be empty");
5839 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5840 assert(free_list != NULL, "pre-condition");
5841
5842 if (G1VerifyBitmaps) {
5843 MemRegion mr(hr->bottom(), hr->end());
5844 concurrent_mark()->clearRangePrevBitmap(mr);
5845 }
5846
5847 // Clear the card counts for this region.
5848 // Note: we only need to do this if the region is not young
5849 // (since we don't refine cards in young regions).
5850 if (!hr->is_young()) {
5851 _cg1r->hot_card_cache()->reset_card_counts(hr);
5852 }
5853 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5854 free_list->add_ordered(hr);
5855 }
5856
5857 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5858 FreeRegionList* free_list,
5859 bool par) {
5860 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5861 assert(free_list != NULL, "pre-condition");
5862
5863 size_t hr_capacity = hr->capacity();
5864 // We need to read this before we make the region non-humongous,
5865 // otherwise the information will be gone.
5866 uint last_index = hr->last_hc_index();
5867 hr->clear_humongous();
5868 free_region(hr, free_list, par);
5869
5870 uint i = hr->hrm_index() + 1;
5871 while (i < last_index) {
5872 HeapRegion* curr_hr = region_at(i);
5873 assert(curr_hr->continuesHumongous(), "invariant");
5874 curr_hr->clear_humongous();
5875 free_region(curr_hr, free_list, par);
5876 i += 1;
5877 }
5878 }
5879
5880 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5881 const HeapRegionSetCount& humongous_regions_removed) {
5882 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5883 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5884 _old_set.bulk_remove(old_regions_removed);
5885 _humongous_set.bulk_remove(humongous_regions_removed);
5886 }
5887
5888 }
5889
5890 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5891 assert(list != NULL, "list can't be null");
5892 if (!list->is_empty()) {
5893 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5894 _hrm.insert_list_into_free_list(list);
5895 }
5896 }
5897
5898 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5899 _allocator->decrease_used(bytes);
5900 }
5901
5902 class G1ParCleanupCTTask : public AbstractGangTask {
5903 G1SATBCardTableModRefBS* _ct_bs;
5904 G1CollectedHeap* _g1h;
5905 HeapRegion* volatile _su_head;
5906 public:
5907 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5908 G1CollectedHeap* g1h) :
5909 AbstractGangTask("G1 Par Cleanup CT Task"),
5910 _ct_bs(ct_bs), _g1h(g1h) { }
5911
5912 void work(uint worker_id) {
5913 HeapRegion* r;
5914 while (r = _g1h->pop_dirty_cards_region()) {
5915 clear_cards(r);
5916 }
5917 }
5918
5919 void clear_cards(HeapRegion* r) {
5920 // Cards of the survivors should have already been dirtied.
5921 if (!r->is_survivor()) {
5922 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5923 }
5924 }
5925 };
5926
5927 #ifndef PRODUCT
5928 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5929 G1CollectedHeap* _g1h;
5930 G1SATBCardTableModRefBS* _ct_bs;
5931 public:
5932 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5933 : _g1h(g1h), _ct_bs(ct_bs) { }
5934 virtual bool doHeapRegion(HeapRegion* r) {
5935 if (r->is_survivor()) {
5936 _g1h->verify_dirty_region(r);
5937 } else {
5938 _g1h->verify_not_dirty_region(r);
5939 }
5940 return false;
5941 }
5942 };
5943
5944 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5945 // All of the region should be clean.
5946 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5947 MemRegion mr(hr->bottom(), hr->end());
5948 ct_bs->verify_not_dirty_region(mr);
5949 }
5950
5951 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5952 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5953 // dirty allocated blocks as they allocate them. The thread that
5954 // retires each region and replaces it with a new one will do a
5955 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5956 // not dirty that area (one less thing to have to do while holding
5957 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5958 // is dirty.
5959 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5960 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5961 if (hr->is_young()) {
5962 ct_bs->verify_g1_young_region(mr);
5963 } else {
5964 ct_bs->verify_dirty_region(mr);
5965 }
5966 }
5967
5968 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5969 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5970 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5971 verify_dirty_region(hr);
5972 }
5973 }
5974
5975 void G1CollectedHeap::verify_dirty_young_regions() {
5976 verify_dirty_young_list(_young_list->first_region());
5977 }
5978
5979 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5980 HeapWord* tams, HeapWord* end) {
5981 guarantee(tams <= end,
5982 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5983 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5984 if (result < end) {
5985 gclog_or_tty->cr();
5986 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5987 bitmap_name, result);
5988 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5989 bitmap_name, tams, end);
5990 return false;
5991 }
5992 return true;
5993 }
5994
5995 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5996 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5997 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5998
5999 HeapWord* bottom = hr->bottom();
6000 HeapWord* ptams = hr->prev_top_at_mark_start();
6001 HeapWord* ntams = hr->next_top_at_mark_start();
6002 HeapWord* end = hr->end();
6003
6004 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6005
6006 bool res_n = true;
6007 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6008 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6009 // if we happen to be in that state.
6010 if (mark_in_progress() || !_cmThread->in_progress()) {
6011 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6012 }
6013 if (!res_p || !res_n) {
6014 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6015 HR_FORMAT_PARAMS(hr));
6016 gclog_or_tty->print_cr("#### Caller: %s", caller);
6017 return false;
6018 }
6019 return true;
6020 }
6021
6022 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6023 if (!G1VerifyBitmaps) return;
6024
6025 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6026 }
6027
6028 class G1VerifyBitmapClosure : public HeapRegionClosure {
6029 private:
6030 const char* _caller;
6031 G1CollectedHeap* _g1h;
6032 bool _failures;
6033
6034 public:
6035 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6036 _caller(caller), _g1h(g1h), _failures(false) { }
6037
6038 bool failures() { return _failures; }
6039
6040 virtual bool doHeapRegion(HeapRegion* hr) {
6041 if (hr->continuesHumongous()) return false;
6042
6043 bool result = _g1h->verify_bitmaps(_caller, hr);
6044 if (!result) {
6045 _failures = true;
6046 }
6047 return false;
6048 }
6049 };
6050
6051 void G1CollectedHeap::check_bitmaps(const char* caller) {
6052 if (!G1VerifyBitmaps) return;
6053
6054 G1VerifyBitmapClosure cl(caller, this);
6055 heap_region_iterate(&cl);
6056 guarantee(!cl.failures(), "bitmap verification");
6057 }
6058 #endif // PRODUCT
6059
6060 void G1CollectedHeap::cleanUpCardTable() {
6061 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6062 double start = os::elapsedTime();
6063
6064 {
6065 // Iterate over the dirty cards region list.
6066 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6067
6068 if (G1CollectedHeap::use_parallel_gc_threads()) {
6069 set_par_threads();
6070 workers()->run_task(&cleanup_task);
6071 set_par_threads(0);
6072 } else {
6073 while (_dirty_cards_region_list) {
6074 HeapRegion* r = _dirty_cards_region_list;
6075 cleanup_task.clear_cards(r);
6076 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6077 if (_dirty_cards_region_list == r) {
6078 // The last region.
6079 _dirty_cards_region_list = NULL;
6080 }
6081 r->set_next_dirty_cards_region(NULL);
6082 }
6083 }
6084 #ifndef PRODUCT
6085 if (G1VerifyCTCleanup || VerifyAfterGC) {
6086 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6087 heap_region_iterate(&cleanup_verifier);
6088 }
6089 #endif
6090 }
6091
6092 double elapsed = os::elapsedTime() - start;
6093 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6094 }
6095
6096 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6097 size_t pre_used = 0;
6098 FreeRegionList local_free_list("Local List for CSet Freeing");
6099
6100 double young_time_ms = 0.0;
6101 double non_young_time_ms = 0.0;
6102
6103 // Since the collection set is a superset of the the young list,
6104 // all we need to do to clear the young list is clear its
6105 // head and length, and unlink any young regions in the code below
6106 _young_list->clear();
6107
6108 G1CollectorPolicy* policy = g1_policy();
6109
6110 double start_sec = os::elapsedTime();
6111 bool non_young = true;
6112
6113 HeapRegion* cur = cs_head;
6114 int age_bound = -1;
6115 size_t rs_lengths = 0;
6116
6117 while (cur != NULL) {
6118 assert(!is_on_master_free_list(cur), "sanity");
6119 if (non_young) {
6120 if (cur->is_young()) {
6121 double end_sec = os::elapsedTime();
6122 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6123 non_young_time_ms += elapsed_ms;
6124
6125 start_sec = os::elapsedTime();
6126 non_young = false;
6127 }
6128 } else {
6129 if (!cur->is_young()) {
6130 double end_sec = os::elapsedTime();
6131 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6132 young_time_ms += elapsed_ms;
6133
6134 start_sec = os::elapsedTime();
6135 non_young = true;
6136 }
6137 }
6138
6139 rs_lengths += cur->rem_set()->occupied_locked();
6140
6141 HeapRegion* next = cur->next_in_collection_set();
6142 assert(cur->in_collection_set(), "bad CS");
6143 cur->set_next_in_collection_set(NULL);
6144 cur->set_in_collection_set(false);
6145
6146 if (cur->is_young()) {
6147 int index = cur->young_index_in_cset();
6148 assert(index != -1, "invariant");
6149 assert((uint) index < policy->young_cset_region_length(), "invariant");
6150 size_t words_survived = _surviving_young_words[index];
6151 cur->record_surv_words_in_group(words_survived);
6152
6153 // At this point the we have 'popped' cur from the collection set
6154 // (linked via next_in_collection_set()) but it is still in the
6155 // young list (linked via next_young_region()). Clear the
6156 // _next_young_region field.
6157 cur->set_next_young_region(NULL);
6158 } else {
6159 int index = cur->young_index_in_cset();
6160 assert(index == -1, "invariant");
6161 }
6162
6163 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6164 (!cur->is_young() && cur->young_index_in_cset() == -1),
6165 "invariant" );
6166
6167 if (!cur->evacuation_failed()) {
6168 MemRegion used_mr = cur->used_region();
6169
6170 // And the region is empty.
6171 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6172 pre_used += cur->used();
6173 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6174 } else {
6175 cur->uninstall_surv_rate_group();
6176 if (cur->is_young()) {
6177 cur->set_young_index_in_cset(-1);
6178 }
6179 cur->set_evacuation_failed(false);
6180 // The region is now considered to be old.
6181 cur->set_old();
6182 _old_set.add(cur);
6183 evacuation_info.increment_collectionset_used_after(cur->used());
6184 }
6185 cur = next;
6186 }
6187
6188 evacuation_info.set_regions_freed(local_free_list.length());
6189 policy->record_max_rs_lengths(rs_lengths);
6190 policy->cset_regions_freed();
6191
6192 double end_sec = os::elapsedTime();
6193 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6194
6195 if (non_young) {
6196 non_young_time_ms += elapsed_ms;
6197 } else {
6198 young_time_ms += elapsed_ms;
6199 }
6200
6201 prepend_to_freelist(&local_free_list);
6202 decrement_summary_bytes(pre_used);
6203 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6204 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6205 }
6206
6207 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6208 private:
6209 FreeRegionList* _free_region_list;
6210 HeapRegionSet* _proxy_set;
6211 HeapRegionSetCount _humongous_regions_removed;
6212 size_t _freed_bytes;
6213 public:
6214
6215 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6216 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6217 }
6218
6219 virtual bool doHeapRegion(HeapRegion* r) {
6220 if (!r->startsHumongous()) {
6221 return false;
6222 }
6223
6224 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6225
6226 oop obj = (oop)r->bottom();
6227 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6228
6229 // The following checks whether the humongous object is live are sufficient.
6230 // The main additional check (in addition to having a reference from the roots
6231 // or the young gen) is whether the humongous object has a remembered set entry.
6232 //
6233 // A humongous object cannot be live if there is no remembered set for it
6234 // because:
6235 // - there can be no references from within humongous starts regions referencing
6236 // the object because we never allocate other objects into them.
6237 // (I.e. there are no intra-region references that may be missed by the
6238 // remembered set)
6239 // - as soon there is a remembered set entry to the humongous starts region
6240 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6241 // until the end of a concurrent mark.
6242 //
6243 // It is not required to check whether the object has been found dead by marking
6244 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6245 // all objects allocated during that time are considered live.
6246 // SATB marking is even more conservative than the remembered set.
6247 // So if at this point in the collection there is no remembered set entry,
6248 // nobody has a reference to it.
6249 // At the start of collection we flush all refinement logs, and remembered sets
6250 // are completely up-to-date wrt to references to the humongous object.
6251 //
6252 // Other implementation considerations:
6253 // - never consider object arrays: while they are a valid target, they have not
6254 // been observed to be used as temporary objects.
6255 // - they would also pose considerable effort for cleaning up the the remembered
6256 // sets.
6257 // While this cleanup is not strictly necessary to be done (or done instantly),
6258 // given that their occurrence is very low, this saves us this additional
6259 // complexity.
6260 uint region_idx = r->hrm_index();
6261 if (g1h->humongous_is_live(region_idx) ||
6262 g1h->humongous_region_is_always_live(region_idx)) {
6263
6264 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6265 gclog_or_tty->print_cr("Live humongous %d region %d size "SIZE_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6266 r->isHumongous(),
6267 region_idx,
6268 obj->size()*HeapWordSize,
6269 r->rem_set()->occupied(),
6270 r->rem_set()->strong_code_roots_list_length(),
6271 next_bitmap->isMarked(r->bottom()),
6272 g1h->humongous_is_live(region_idx),
6273 obj->is_objArray()
6274 );
6275 }
6276
6277 return false;
6278 }
6279
6280 guarantee(!obj->is_objArray(),
6281 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6282 r->bottom()));
6283
6284 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6285 gclog_or_tty->print_cr("Reclaim humongous region %d size "SIZE_FORMAT" start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other ",
6286 r->isHumongous(),
6287 obj->size()*HeapWordSize,
6288 r->bottom(),
6289 region_idx,
6290 r->region_num(),
6291 r->rem_set()->occupied(),
6292 r->rem_set()->strong_code_roots_list_length(),
6293 next_bitmap->isMarked(r->bottom()),
6294 g1h->humongous_is_live(region_idx),
6295 obj->is_objArray()
6296 );
6297 }
6298 // Need to clear mark bit of the humongous object if already set.
6299 if (next_bitmap->isMarked(r->bottom())) {
6300 next_bitmap->clear(r->bottom());
6301 }
6302 _freed_bytes += r->used();
6303 r->set_containing_set(NULL);
6304 _humongous_regions_removed.increment(1u, r->capacity());
6305 g1h->free_humongous_region(r, _free_region_list, false);
6306
6307 return false;
6308 }
6309
6310 HeapRegionSetCount& humongous_free_count() {
6311 return _humongous_regions_removed;
6312 }
6313
6314 size_t bytes_freed() const {
6315 return _freed_bytes;
6316 }
6317
6318 size_t humongous_reclaimed() const {
6319 return _humongous_regions_removed.length();
6320 }
6321 };
6322
6323 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6324 assert_at_safepoint(true);
6325
6326 if (!G1ReclaimDeadHumongousObjectsAtYoungGC ||
6327 (!_has_humongous_reclaim_candidates && !G1TraceReclaimDeadHumongousObjectsAtYoungGC)) {
6328 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6329 return;
6330 }
6331
6332 double start_time = os::elapsedTime();
6333
6334 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6335
6336 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6337 heap_region_iterate(&cl);
6338
6339 HeapRegionSetCount empty_set;
6340 remove_from_old_sets(empty_set, cl.humongous_free_count());
6341
6342 G1HRPrinter* hr_printer = _g1h->hr_printer();
6343 if (hr_printer->is_active()) {
6344 FreeRegionListIterator iter(&local_cleanup_list);
6345 while (iter.more_available()) {
6346 HeapRegion* hr = iter.get_next();
6347 hr_printer->cleanup(hr);
6348 }
6349 }
6350
6351 prepend_to_freelist(&local_cleanup_list);
6352 decrement_summary_bytes(cl.bytes_freed());
6353
6354 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6355 cl.humongous_reclaimed());
6356 }
6357
6358 // This routine is similar to the above but does not record
6359 // any policy statistics or update free lists; we are abandoning
6360 // the current incremental collection set in preparation of a
6361 // full collection. After the full GC we will start to build up
6362 // the incremental collection set again.
6363 // This is only called when we're doing a full collection
6364 // and is immediately followed by the tearing down of the young list.
6365
6366 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6367 HeapRegion* cur = cs_head;
6368
6369 while (cur != NULL) {
6370 HeapRegion* next = cur->next_in_collection_set();
6371 assert(cur->in_collection_set(), "bad CS");
6372 cur->set_next_in_collection_set(NULL);
6373 cur->set_in_collection_set(false);
6374 cur->set_young_index_in_cset(-1);
6375 cur = next;
6376 }
6377 }
6378
6379 void G1CollectedHeap::set_free_regions_coming() {
6380 if (G1ConcRegionFreeingVerbose) {
6381 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6382 "setting free regions coming");
6383 }
6384
6385 assert(!free_regions_coming(), "pre-condition");
6386 _free_regions_coming = true;
6387 }
6388
6389 void G1CollectedHeap::reset_free_regions_coming() {
6390 assert(free_regions_coming(), "pre-condition");
6391
6392 {
6393 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6394 _free_regions_coming = false;
6395 SecondaryFreeList_lock->notify_all();
6396 }
6397
6398 if (G1ConcRegionFreeingVerbose) {
6399 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6400 "reset free regions coming");
6401 }
6402 }
6403
6404 void G1CollectedHeap::wait_while_free_regions_coming() {
6405 // Most of the time we won't have to wait, so let's do a quick test
6406 // first before we take the lock.
6407 if (!free_regions_coming()) {
6408 return;
6409 }
6410
6411 if (G1ConcRegionFreeingVerbose) {
6412 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6413 "waiting for free regions");
6414 }
6415
6416 {
6417 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6418 while (free_regions_coming()) {
6419 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6420 }
6421 }
6422
6423 if (G1ConcRegionFreeingVerbose) {
6424 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6425 "done waiting for free regions");
6426 }
6427 }
6428
6429 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6430 assert(heap_lock_held_for_gc(),
6431 "the heap lock should already be held by or for this thread");
6432 _young_list->push_region(hr);
6433 }
6434
6435 class NoYoungRegionsClosure: public HeapRegionClosure {
6436 private:
6437 bool _success;
6438 public:
6439 NoYoungRegionsClosure() : _success(true) { }
6440 bool doHeapRegion(HeapRegion* r) {
6441 if (r->is_young()) {
6442 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6443 r->bottom(), r->end());
6444 _success = false;
6445 }
6446 return false;
6447 }
6448 bool success() { return _success; }
6449 };
6450
6451 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6452 bool ret = _young_list->check_list_empty(check_sample);
6453
6454 if (check_heap) {
6455 NoYoungRegionsClosure closure;
6456 heap_region_iterate(&closure);
6457 ret = ret && closure.success();
6458 }
6459
6460 return ret;
6461 }
6462
6463 class TearDownRegionSetsClosure : public HeapRegionClosure {
6464 private:
6465 HeapRegionSet *_old_set;
6466
6467 public:
6468 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6469
6470 bool doHeapRegion(HeapRegion* r) {
6471 if (r->is_old()) {
6472 _old_set->remove(r);
6473 } else {
6474 // We ignore free regions, we'll empty the free list afterwards.
6475 // We ignore young regions, we'll empty the young list afterwards.
6476 // We ignore humongous regions, we're not tearing down the
6477 // humongous regions set.
6478 assert(r->is_free() || r->is_young() || r->isHumongous(),
6479 "it cannot be another type");
6480 }
6481 return false;
6482 }
6483
6484 ~TearDownRegionSetsClosure() {
6485 assert(_old_set->is_empty(), "post-condition");
6486 }
6487 };
6488
6489 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6490 assert_at_safepoint(true /* should_be_vm_thread */);
6491
6492 if (!free_list_only) {
6493 TearDownRegionSetsClosure cl(&_old_set);
6494 heap_region_iterate(&cl);
6495
6496 // Note that emptying the _young_list is postponed and instead done as
6497 // the first step when rebuilding the regions sets again. The reason for
6498 // this is that during a full GC string deduplication needs to know if
6499 // a collected region was young or old when the full GC was initiated.
6500 }
6501 _hrm.remove_all_free_regions();
6502 }
6503
6504 class RebuildRegionSetsClosure : public HeapRegionClosure {
6505 private:
6506 bool _free_list_only;
6507 HeapRegionSet* _old_set;
6508 HeapRegionManager* _hrm;
6509 size_t _total_used;
6510
6511 public:
6512 RebuildRegionSetsClosure(bool free_list_only,
6513 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6514 _free_list_only(free_list_only),
6515 _old_set(old_set), _hrm(hrm), _total_used(0) {
6516 assert(_hrm->num_free_regions() == 0, "pre-condition");
6517 if (!free_list_only) {
6518 assert(_old_set->is_empty(), "pre-condition");
6519 }
6520 }
6521
6522 bool doHeapRegion(HeapRegion* r) {
6523 if (r->continuesHumongous()) {
6524 return false;
6525 }
6526
6527 if (r->is_empty()) {
6528 // Add free regions to the free list
6529 r->set_free();
6530 r->set_allocation_context(AllocationContext::system());
6531 _hrm->insert_into_free_list(r);
6532 } else if (!_free_list_only) {
6533 assert(!r->is_young(), "we should not come across young regions");
6534
6535 if (r->isHumongous()) {
6536 // We ignore humongous regions, we left the humongous set unchanged
6537 } else {
6538 // Objects that were compacted would have ended up on regions
6539 // that were previously old or free.
6540 assert(r->is_free() || r->is_old(), "invariant");
6541 // We now consider them old, so register as such.
6542 r->set_old();
6543 _old_set->add(r);
6544 }
6545 _total_used += r->used();
6546 }
6547
6548 return false;
6549 }
6550
6551 size_t total_used() {
6552 return _total_used;
6553 }
6554 };
6555
6556 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6557 assert_at_safepoint(true /* should_be_vm_thread */);
6558
6559 if (!free_list_only) {
6560 _young_list->empty_list();
6561 }
6562
6563 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6564 heap_region_iterate(&cl);
6565
6566 if (!free_list_only) {
6567 _allocator->set_used(cl.total_used());
6568 }
6569 assert(_allocator->used_unlocked() == recalculate_used(),
6570 err_msg("inconsistent _allocator->used_unlocked(), "
6571 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6572 _allocator->used_unlocked(), recalculate_used()));
6573 }
6574
6575 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6576 _refine_cte_cl->set_concurrent(concurrent);
6577 }
6578
6579 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6580 HeapRegion* hr = heap_region_containing(p);
6581 return hr->is_in(p);
6582 }
6583
6584 // Methods for the mutator alloc region
6585
6586 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6587 bool force) {
6588 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6589 assert(!force || g1_policy()->can_expand_young_list(),
6590 "if force is true we should be able to expand the young list");
6591 bool young_list_full = g1_policy()->is_young_list_full();
6592 if (force || !young_list_full) {
6593 HeapRegion* new_alloc_region = new_region(word_size,
6594 false /* is_old */,
6595 false /* do_expand */);
6596 if (new_alloc_region != NULL) {
6597 set_region_short_lived_locked(new_alloc_region);
6598 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6599 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6600 return new_alloc_region;
6601 }
6602 }
6603 return NULL;
6604 }
6605
6606 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6607 size_t allocated_bytes) {
6608 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6609 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6610
6611 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6612 _allocator->increase_used(allocated_bytes);
6613 _hr_printer.retire(alloc_region);
6614 // We update the eden sizes here, when the region is retired,
6615 // instead of when it's allocated, since this is the point that its
6616 // used space has been recored in _summary_bytes_used.
6617 g1mm()->update_eden_size();
6618 }
6619
6620 void G1CollectedHeap::set_par_threads() {
6621 // Don't change the number of workers. Use the value previously set
6622 // in the workgroup.
6623 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6624 uint n_workers = workers()->active_workers();
6625 assert(UseDynamicNumberOfGCThreads ||
6626 n_workers == workers()->total_workers(),
6627 "Otherwise should be using the total number of workers");
6628 if (n_workers == 0) {
6629 assert(false, "Should have been set in prior evacuation pause.");
6630 n_workers = ParallelGCThreads;
6631 workers()->set_active_workers(n_workers);
6632 }
6633 set_par_threads(n_workers);
6634 }
6635
6636 // Methods for the GC alloc regions
6637
6638 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6639 uint count,
6640 GCAllocPurpose ap) {
6641 assert(FreeList_lock->owned_by_self(), "pre-condition");
6642
6643 if (count < g1_policy()->max_regions(ap)) {
6644 bool survivor = (ap == GCAllocForSurvived);
6645 HeapRegion* new_alloc_region = new_region(word_size,
6646 !survivor,
6647 true /* do_expand */);
6648 if (new_alloc_region != NULL) {
6649 // We really only need to do this for old regions given that we
6650 // should never scan survivors. But it doesn't hurt to do it
6651 // for survivors too.
6652 new_alloc_region->record_top_and_timestamp();
6653 if (survivor) {
6654 new_alloc_region->set_survivor();
6655 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6656 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6657 } else {
6658 new_alloc_region->set_old();
6659 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6660 check_bitmaps("Old Region Allocation", new_alloc_region);
6661 }
6662 bool during_im = g1_policy()->during_initial_mark_pause();
6663 new_alloc_region->note_start_of_copying(during_im);
6664 return new_alloc_region;
6665 } else {
6666 g1_policy()->note_alloc_region_limit_reached(ap);
6667 }
6668 }
6669 return NULL;
6670 }
6671
6672 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6673 size_t allocated_bytes,
6674 GCAllocPurpose ap) {
6675 bool during_im = g1_policy()->during_initial_mark_pause();
6676 alloc_region->note_end_of_copying(during_im);
6677 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6678 if (ap == GCAllocForSurvived) {
6679 young_list()->add_survivor_region(alloc_region);
6680 } else {
6681 _old_set.add(alloc_region);
6682 }
6683 _hr_printer.retire(alloc_region);
6684 }
6685
6686 // Heap region set verification
6687
6688 class VerifyRegionListsClosure : public HeapRegionClosure {
6689 private:
6690 HeapRegionSet* _old_set;
6691 HeapRegionSet* _humongous_set;
6692 HeapRegionManager* _hrm;
6693
6694 public:
6695 HeapRegionSetCount _old_count;
6696 HeapRegionSetCount _humongous_count;
6697 HeapRegionSetCount _free_count;
6698
6699 VerifyRegionListsClosure(HeapRegionSet* old_set,
6700 HeapRegionSet* humongous_set,
6701 HeapRegionManager* hrm) :
6702 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6703 _old_count(), _humongous_count(), _free_count(){ }
6704
6705 bool doHeapRegion(HeapRegion* hr) {
6706 if (hr->continuesHumongous()) {
6707 return false;
6708 }
6709
6710 if (hr->is_young()) {
6711 // TODO
6712 } else if (hr->startsHumongous()) {
6713 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6714 _humongous_count.increment(1u, hr->capacity());
6715 } else if (hr->is_empty()) {
6716 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6717 _free_count.increment(1u, hr->capacity());
6718 } else if (hr->is_old()) {
6719 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6720 _old_count.increment(1u, hr->capacity());
6721 } else {
6722 ShouldNotReachHere();
6723 }
6724 return false;
6725 }
6726
6727 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6728 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6729 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6730 old_set->total_capacity_bytes(), _old_count.capacity()));
6731
6732 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6733 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6734 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6735
6736 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()));
6737 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6738 free_list->total_capacity_bytes(), _free_count.capacity()));
6739 }
6740 };
6741
6742 void G1CollectedHeap::verify_region_sets() {
6743 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6744
6745 // First, check the explicit lists.
6746 _hrm.verify();
6747 {
6748 // Given that a concurrent operation might be adding regions to
6749 // the secondary free list we have to take the lock before
6750 // verifying it.
6751 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6752 _secondary_free_list.verify_list();
6753 }
6754
6755 // If a concurrent region freeing operation is in progress it will
6756 // be difficult to correctly attributed any free regions we come
6757 // across to the correct free list given that they might belong to
6758 // one of several (free_list, secondary_free_list, any local lists,
6759 // etc.). So, if that's the case we will skip the rest of the
6760 // verification operation. Alternatively, waiting for the concurrent
6761 // operation to complete will have a non-trivial effect on the GC's
6762 // operation (no concurrent operation will last longer than the
6763 // interval between two calls to verification) and it might hide
6764 // any issues that we would like to catch during testing.
6765 if (free_regions_coming()) {
6766 return;
6767 }
6768
6769 // Make sure we append the secondary_free_list on the free_list so
6770 // that all free regions we will come across can be safely
6771 // attributed to the free_list.
6772 append_secondary_free_list_if_not_empty_with_lock();
6773
6774 // Finally, make sure that the region accounting in the lists is
6775 // consistent with what we see in the heap.
6776
6777 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6778 heap_region_iterate(&cl);
6779 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6780 }
6781
6782 // Optimized nmethod scanning
6783
6784 class RegisterNMethodOopClosure: public OopClosure {
6785 G1CollectedHeap* _g1h;
6786 nmethod* _nm;
6787
6788 template <class T> void do_oop_work(T* p) {
6789 T heap_oop = oopDesc::load_heap_oop(p);
6790 if (!oopDesc::is_null(heap_oop)) {
6791 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6792 HeapRegion* hr = _g1h->heap_region_containing(obj);
6793 assert(!hr->continuesHumongous(),
6794 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6795 " starting at "HR_FORMAT,
6796 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6797
6798 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6799 hr->add_strong_code_root_locked(_nm);
6800 }
6801 }
6802
6803 public:
6804 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6805 _g1h(g1h), _nm(nm) {}
6806
6807 void do_oop(oop* p) { do_oop_work(p); }
6808 void do_oop(narrowOop* p) { do_oop_work(p); }
6809 };
6810
6811 class UnregisterNMethodOopClosure: public OopClosure {
6812 G1CollectedHeap* _g1h;
6813 nmethod* _nm;
6814
6815 template <class T> void do_oop_work(T* p) {
6816 T heap_oop = oopDesc::load_heap_oop(p);
6817 if (!oopDesc::is_null(heap_oop)) {
6818 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6819 HeapRegion* hr = _g1h->heap_region_containing(obj);
6820 assert(!hr->continuesHumongous(),
6821 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6822 " starting at "HR_FORMAT,
6823 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6824
6825 hr->remove_strong_code_root(_nm);
6826 }
6827 }
6828
6829 public:
6830 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6831 _g1h(g1h), _nm(nm) {}
6832
6833 void do_oop(oop* p) { do_oop_work(p); }
6834 void do_oop(narrowOop* p) { do_oop_work(p); }
6835 };
6836
6837 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6838 CollectedHeap::register_nmethod(nm);
6839
6840 guarantee(nm != NULL, "sanity");
6841 RegisterNMethodOopClosure reg_cl(this, nm);
6842 nm->oops_do(®_cl);
6843 }
6844
6845 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6846 CollectedHeap::unregister_nmethod(nm);
6847
6848 guarantee(nm != NULL, "sanity");
6849 UnregisterNMethodOopClosure reg_cl(this, nm);
6850 nm->oops_do(®_cl, true);
6851 }
6852
6853 void G1CollectedHeap::purge_code_root_memory() {
6854 double purge_start = os::elapsedTime();
6855 G1CodeRootSet::purge();
6856 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6857 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6858 }
6859
6860 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6861 G1CollectedHeap* _g1h;
6862
6863 public:
6864 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6865 _g1h(g1h) {}
6866
6867 void do_code_blob(CodeBlob* cb) {
6868 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6869 if (nm == NULL) {
6870 return;
6871 }
6872
6873 if (ScavengeRootsInCode) {
6874 _g1h->register_nmethod(nm);
6875 }
6876 }
6877 };
6878
6879 void G1CollectedHeap::rebuild_strong_code_roots() {
6880 RebuildStrongCodeRootClosure blob_cl(this);
6881 CodeCache::blobs_do(&blob_cl);
6882 }