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/g1StringDedup.hpp"
50 #include "gc_implementation/g1/g1YCTypes.hpp"
51 #include "gc_implementation/g1/heapRegion.inline.hpp"
52 #include "gc_implementation/g1/heapRegionRemSet.hpp"
53 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
54 #include "gc_implementation/g1/vm_operations_g1.hpp"
55 #include "gc_implementation/shared/gcHeapSummary.hpp"
56 #include "gc_implementation/shared/gcTimer.hpp"
57 #include "gc_implementation/shared/gcTrace.hpp"
58 #include "gc_implementation/shared/gcTraceTime.hpp"
59 #include "gc_implementation/shared/isGCActiveMark.hpp"
60 #include "memory/allocation.hpp"
61 #include "memory/gcLocker.inline.hpp"
62 #include "memory/generationSpec.hpp"
63 #include "memory/iterator.hpp"
64 #include "memory/referenceProcessor.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/oop.pcgc.inline.hpp"
67 #include "runtime/orderAccess.inline.hpp"
68 #include "runtime/vmThread.hpp"
69
70 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
71
72 // turn it on so that the contents of the young list (scan-only /
73 // to-be-collected) are printed at "strategic" points before / during
74 // / after the collection --- this is useful for debugging
75 #define YOUNG_LIST_VERBOSE 0
76 // CURRENT STATUS
77 // This file is under construction. Search for "FIXME".
78
79 // INVARIANTS/NOTES
80 //
81 // All allocation activity covered by the G1CollectedHeap interface is
82 // serialized by acquiring the HeapLock. This happens in mem_allocate
83 // and allocate_new_tlab, which are the "entry" points to the
84 // allocation code from the rest of the JVM. (Note that this does not
85 // apply to TLAB allocation, which is not part of this interface: it
86 // is done by clients of this interface.)
87
88 // Notes on implementation of parallelism in different tasks.
89 //
90 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
91 // The number of GC workers is passed to heap_region_par_iterate_chunked().
92 // It does use run_task() which sets _n_workers in the task.
93 // G1ParTask executes g1_process_roots() ->
94 // SharedHeap::process_roots() which calls eventually to
95 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
96 // SequentialSubTasksDone. SharedHeap::process_roots() also
97 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
98 //
99
100 // Local to this file.
101
102 class RefineCardTableEntryClosure: public CardTableEntryClosure {
103 bool _concurrent;
104 public:
105 RefineCardTableEntryClosure() : _concurrent(true) { }
106
107 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
108 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
109 // This path is executed by the concurrent refine or mutator threads,
110 // concurrently, and so we do not care if card_ptr contains references
111 // that point into the collection set.
112 assert(!oops_into_cset, "should be");
113
114 if (_concurrent && SuspendibleThreadSet::should_yield()) {
115 // Caller will actually yield.
116 return false;
117 }
118 // Otherwise, we finished successfully; return true.
119 return true;
120 }
121
122 void set_concurrent(bool b) { _concurrent = b; }
123 };
124
125
126 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
127 size_t _num_processed;
128 CardTableModRefBS* _ctbs;
129 int _histo[256];
130
131 public:
132 ClearLoggedCardTableEntryClosure() :
133 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
134 {
135 for (int i = 0; i < 256; i++) _histo[i] = 0;
136 }
137
138 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
139 unsigned char* ujb = (unsigned char*)card_ptr;
140 int ind = (int)(*ujb);
141 _histo[ind]++;
142
143 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
144 _num_processed++;
145
146 return true;
147 }
148
149 size_t num_processed() { return _num_processed; }
150
151 void print_histo() {
152 gclog_or_tty->print_cr("Card table value histogram:");
153 for (int i = 0; i < 256; i++) {
154 if (_histo[i] != 0) {
155 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
156 }
157 }
158 }
159 };
160
161 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
162 private:
163 size_t _num_processed;
164
165 public:
166 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
167
168 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
169 *card_ptr = CardTableModRefBS::dirty_card_val();
170 _num_processed++;
171 return true;
172 }
173
174 size_t num_processed() const { return _num_processed; }
175 };
176
177 YoungList::YoungList(G1CollectedHeap* g1h) :
178 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
179 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
180 guarantee(check_list_empty(false), "just making sure...");
181 }
182
183 void YoungList::push_region(HeapRegion *hr) {
184 assert(!hr->is_young(), "should not already be young");
185 assert(hr->get_next_young_region() == NULL, "cause it should!");
186
187 hr->set_next_young_region(_head);
188 _head = hr;
189
190 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
191 ++_length;
192 }
193
194 void YoungList::add_survivor_region(HeapRegion* hr) {
195 assert(hr->is_survivor(), "should be flagged as survivor region");
196 assert(hr->get_next_young_region() == NULL, "cause it should!");
197
198 hr->set_next_young_region(_survivor_head);
199 if (_survivor_head == NULL) {
200 _survivor_tail = hr;
201 }
202 _survivor_head = hr;
203 ++_survivor_length;
204 }
205
206 void YoungList::empty_list(HeapRegion* list) {
207 while (list != NULL) {
208 HeapRegion* next = list->get_next_young_region();
209 list->set_next_young_region(NULL);
210 list->uninstall_surv_rate_group();
211 // This is called before a Full GC and all the non-empty /
212 // non-humongous regions at the end of the Full GC will end up as
213 // old anyway.
214 list->set_old();
215 list = next;
216 }
217 }
218
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
221
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
225
226 empty_list(_survivor_head);
227 _survivor_head = NULL;
228 _survivor_tail = NULL;
229 _survivor_length = 0;
230
231 _last_sampled_rs_lengths = 0;
232
233 assert(check_list_empty(false), "just making sure...");
234 }
235
236 bool YoungList::check_list_well_formed() {
237 bool ret = true;
238
239 uint length = 0;
240 HeapRegion* curr = _head;
241 HeapRegion* last = NULL;
242 while (curr != NULL) {
243 if (!curr->is_young()) {
244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
245 "incorrectly tagged (y: %d, surv: %d)",
246 curr->bottom(), curr->end(),
247 curr->is_young(), curr->is_survivor());
248 ret = false;
249 }
250 ++length;
251 last = curr;
252 curr = curr->get_next_young_region();
253 }
254 ret = ret && (length == _length);
255
256 if (!ret) {
257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
258 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
259 length, _length);
260 }
261
262 return ret;
263 }
264
265 bool YoungList::check_list_empty(bool check_sample) {
266 bool ret = true;
267
268 if (_length != 0) {
269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
270 _length);
271 ret = false;
272 }
273 if (check_sample && _last_sampled_rs_lengths != 0) {
274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
275 ret = false;
276 }
277 if (_head != NULL) {
278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
279 ret = false;
280 }
281 if (!ret) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
283 }
284
285 return ret;
286 }
287
288 void
289 YoungList::rs_length_sampling_init() {
290 _sampled_rs_lengths = 0;
291 _curr = _head;
292 }
293
294 bool
295 YoungList::rs_length_sampling_more() {
296 return _curr != NULL;
297 }
298
299 void
300 YoungList::rs_length_sampling_next() {
301 assert( _curr != NULL, "invariant" );
302 size_t rs_length = _curr->rem_set()->occupied();
303
304 _sampled_rs_lengths += rs_length;
305
306 // The current region may not yet have been added to the
307 // incremental collection set (it gets added when it is
308 // retired as the current allocation region).
309 if (_curr->in_collection_set()) {
310 // Update the collection set policy information for this region
311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
312 }
313
314 _curr = _curr->get_next_young_region();
315 if (_curr == NULL) {
316 _last_sampled_rs_lengths = _sampled_rs_lengths;
317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
318 }
319 }
320
321 void
322 YoungList::reset_auxilary_lists() {
323 guarantee( is_empty(), "young list should be empty" );
324 assert(check_list_well_formed(), "young list should be well formed");
325
326 // Add survivor regions to SurvRateGroup.
327 _g1h->g1_policy()->note_start_adding_survivor_regions();
328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
329
330 int young_index_in_cset = 0;
331 for (HeapRegion* curr = _survivor_head;
332 curr != NULL;
333 curr = curr->get_next_young_region()) {
334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
335
336 // The region is a non-empty survivor so let's add it to
337 // the incremental collection set for the next evacuation
338 // pause.
339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
340 young_index_in_cset += 1;
341 }
342 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
343 _g1h->g1_policy()->note_stop_adding_survivor_regions();
344
345 _head = _survivor_head;
346 _length = _survivor_length;
347 if (_survivor_head != NULL) {
348 assert(_survivor_tail != NULL, "cause it shouldn't be");
349 assert(_survivor_length > 0, "invariant");
350 _survivor_tail->set_next_young_region(NULL);
351 }
352
353 // Don't clear the survivor list handles until the start of
354 // the next evacuation pause - we need it in order to re-tag
355 // the survivor regions from this evacuation pause as 'young'
356 // at the start of the next.
357
358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
359
360 assert(check_list_well_formed(), "young list should be well formed");
361 }
362
363 void YoungList::print() {
364 HeapRegion* lists[] = {_head, _survivor_head};
365 const char* names[] = {"YOUNG", "SURVIVOR"};
366
367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
369 HeapRegion *curr = lists[list];
370 if (curr == NULL)
371 gclog_or_tty->print_cr(" empty");
372 while (curr != NULL) {
373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
374 HR_FORMAT_PARAMS(curr),
375 curr->prev_top_at_mark_start(),
376 curr->next_top_at_mark_start(),
377 curr->age_in_surv_rate_group_cond());
378 curr = curr->get_next_young_region();
379 }
380 }
381
382 gclog_or_tty->cr();
383 }
384
385 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
386 OtherRegionsTable::invalidate(start_idx, num_regions);
387 }
388
389 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
390 // The from card cache is not the memory that is actually committed. So we cannot
391 // take advantage of the zero_filled parameter.
392 reset_from_card_cache(start_idx, num_regions);
393 }
394
395 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
396 {
397 // Claim the right to put the region on the dirty cards region list
398 // by installing a self pointer.
399 HeapRegion* next = hr->get_next_dirty_cards_region();
400 if (next == NULL) {
401 HeapRegion* res = (HeapRegion*)
402 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
403 NULL);
404 if (res == NULL) {
405 HeapRegion* head;
406 do {
407 // Put the region to the dirty cards region list.
408 head = _dirty_cards_region_list;
409 next = (HeapRegion*)
410 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
411 if (next == head) {
412 assert(hr->get_next_dirty_cards_region() == hr,
413 "hr->get_next_dirty_cards_region() != hr");
414 if (next == NULL) {
415 // The last region in the list points to itself.
416 hr->set_next_dirty_cards_region(hr);
417 } else {
418 hr->set_next_dirty_cards_region(next);
419 }
420 }
421 } while (next != head);
422 }
423 }
424 }
425
426 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
427 {
428 HeapRegion* head;
429 HeapRegion* hr;
430 do {
431 head = _dirty_cards_region_list;
432 if (head == NULL) {
433 return NULL;
434 }
435 HeapRegion* new_head = head->get_next_dirty_cards_region();
436 if (head == new_head) {
437 // The last region.
438 new_head = NULL;
439 }
440 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
441 head);
442 } while (hr != head);
443 assert(hr != NULL, "invariant");
444 hr->set_next_dirty_cards_region(NULL);
445 return hr;
446 }
447
448 #ifdef ASSERT
449 // A region is added to the collection set as it is retired
450 // so an address p can point to a region which will be in the
451 // collection set but has not yet been retired. This method
452 // therefore is only accurate during a GC pause after all
453 // regions have been retired. It is used for debugging
454 // to check if an nmethod has references to objects that can
455 // be move during a partial collection. Though it can be
456 // inaccurate, it is sufficient for G1 because the conservative
457 // implementation of is_scavengable() for G1 will indicate that
458 // all nmethods must be scanned during a partial collection.
459 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
460 if (p == NULL) {
461 return false;
462 }
463 return heap_region_containing(p)->in_collection_set();
464 }
465 #endif
466
467 // Returns true if the reference points to an object that
468 // can move in an incremental collection.
469 bool G1CollectedHeap::is_scavengable(const void* p) {
470 HeapRegion* hr = heap_region_containing(p);
471 return !hr->isHumongous();
472 }
473
474 void G1CollectedHeap::check_ct_logs_at_safepoint() {
475 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
476 CardTableModRefBS* ct_bs = g1_barrier_set();
477
478 // Count the dirty cards at the start.
479 CountNonCleanMemRegionClosure count1(this);
480 ct_bs->mod_card_iterate(&count1);
481 int orig_count = count1.n();
482
483 // First clear the logged cards.
484 ClearLoggedCardTableEntryClosure clear;
485 dcqs.apply_closure_to_all_completed_buffers(&clear);
486 dcqs.iterate_closure_all_threads(&clear, false);
487 clear.print_histo();
488
489 // Now ensure that there's no dirty cards.
490 CountNonCleanMemRegionClosure count2(this);
491 ct_bs->mod_card_iterate(&count2);
492 if (count2.n() != 0) {
493 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
494 count2.n(), orig_count);
495 }
496 guarantee(count2.n() == 0, "Card table should be clean.");
497
498 RedirtyLoggedCardTableEntryClosure redirty;
499 dcqs.apply_closure_to_all_completed_buffers(&redirty);
500 dcqs.iterate_closure_all_threads(&redirty, false);
501 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
502 clear.num_processed(), orig_count);
503 guarantee(redirty.num_processed() == clear.num_processed(),
504 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
505 redirty.num_processed(), clear.num_processed()));
506
507 CountNonCleanMemRegionClosure count3(this);
508 ct_bs->mod_card_iterate(&count3);
509 if (count3.n() != orig_count) {
510 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
511 orig_count, count3.n());
512 guarantee(count3.n() >= orig_count, "Should have restored them all.");
513 }
514 }
515
516 // Private class members.
517
518 G1CollectedHeap* G1CollectedHeap::_g1h;
519
520 // Private methods.
521
522 HeapRegion*
523 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
524 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
525 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
526 if (!_secondary_free_list.is_empty()) {
527 if (G1ConcRegionFreeingVerbose) {
528 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
529 "secondary_free_list has %u entries",
530 _secondary_free_list.length());
531 }
532 // It looks as if there are free regions available on the
533 // secondary_free_list. Let's move them to the free_list and try
534 // again to allocate from it.
535 append_secondary_free_list();
536
537 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
538 "empty we should have moved at least one entry to the free_list");
539 HeapRegion* res = _hrm.allocate_free_region(is_old);
540 if (G1ConcRegionFreeingVerbose) {
541 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
542 "allocated "HR_FORMAT" from secondary_free_list",
543 HR_FORMAT_PARAMS(res));
544 }
545 return res;
546 }
547
548 // Wait here until we get notified either when (a) there are no
549 // more free regions coming or (b) some regions have been moved on
550 // the secondary_free_list.
551 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
552 }
553
554 if (G1ConcRegionFreeingVerbose) {
555 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
556 "could not allocate from secondary_free_list");
557 }
558 return NULL;
559 }
560
561 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
562 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
563 "the only time we use this to allocate a humongous region is "
564 "when we are allocating a single humongous region");
565
566 HeapRegion* res;
567 if (G1StressConcRegionFreeing) {
568 if (!_secondary_free_list.is_empty()) {
569 if (G1ConcRegionFreeingVerbose) {
570 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
571 "forced to look at the secondary_free_list");
572 }
573 res = new_region_try_secondary_free_list(is_old);
574 if (res != NULL) {
575 return res;
576 }
577 }
578 }
579
580 res = _hrm.allocate_free_region(is_old);
581
582 if (res == NULL) {
583 if (G1ConcRegionFreeingVerbose) {
584 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
585 "res == NULL, trying the secondary_free_list");
586 }
587 res = new_region_try_secondary_free_list(is_old);
588 }
589 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
590 // Currently, only attempts to allocate GC alloc regions set
591 // do_expand to true. So, we should only reach here during a
592 // safepoint. If this assumption changes we might have to
593 // reconsider the use of _expand_heap_after_alloc_failure.
594 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
595
596 ergo_verbose1(ErgoHeapSizing,
597 "attempt heap expansion",
598 ergo_format_reason("region allocation request failed")
599 ergo_format_byte("allocation request"),
600 word_size * HeapWordSize);
601 if (expand(word_size * HeapWordSize)) {
602 // Given that expand() succeeded in expanding the heap, and we
603 // always expand the heap by an amount aligned to the heap
604 // region size, the free list should in theory not be empty.
605 // In either case allocate_free_region() will check for NULL.
606 res = _hrm.allocate_free_region(is_old);
607 } else {
608 _expand_heap_after_alloc_failure = false;
609 }
610 }
611 return res;
612 }
613
614 HeapWord*
615 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
616 uint num_regions,
617 size_t word_size,
618 AllocationContext_t context) {
619 assert(first != G1_NO_HRM_INDEX, "pre-condition");
620 assert(isHumongous(word_size), "word_size should be humongous");
621 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
622
623 // Index of last region in the series + 1.
624 uint last = first + num_regions;
625
626 // We need to initialize the region(s) we just discovered. This is
627 // a bit tricky given that it can happen concurrently with
628 // refinement threads refining cards on these regions and
629 // potentially wanting to refine the BOT as they are scanning
630 // those cards (this can happen shortly after a cleanup; see CR
631 // 6991377). So we have to set up the region(s) carefully and in
632 // a specific order.
633
634 // The word size sum of all the regions we will allocate.
635 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
636 assert(word_size <= word_size_sum, "sanity");
637
638 // This will be the "starts humongous" region.
639 HeapRegion* first_hr = region_at(first);
640 // The header of the new object will be placed at the bottom of
641 // the first region.
642 HeapWord* new_obj = first_hr->bottom();
643 // This will be the new end of the first region in the series that
644 // should also match the end of the last region in the series.
645 HeapWord* new_end = new_obj + word_size_sum;
646 // This will be the new top of the first region that will reflect
647 // this allocation.
648 HeapWord* new_top = new_obj + word_size;
649
650 // First, we need to zero the header of the space that we will be
651 // allocating. When we update top further down, some refinement
652 // threads might try to scan the region. By zeroing the header we
653 // ensure that any thread that will try to scan the region will
654 // come across the zero klass word and bail out.
655 //
656 // NOTE: It would not have been correct to have used
657 // CollectedHeap::fill_with_object() and make the space look like
658 // an int array. The thread that is doing the allocation will
659 // later update the object header to a potentially different array
660 // type and, for a very short period of time, the klass and length
661 // fields will be inconsistent. This could cause a refinement
662 // thread to calculate the object size incorrectly.
663 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
664
665 // We will set up the first region as "starts humongous". This
666 // will also update the BOT covering all the regions to reflect
667 // that there is a single object that starts at the bottom of the
668 // first region.
669 first_hr->set_startsHumongous(new_top, new_end);
670 first_hr->set_allocation_context(context);
671 // Then, if there are any, we will set up the "continues
672 // humongous" regions.
673 HeapRegion* hr = NULL;
674 for (uint i = first + 1; i < last; ++i) {
675 hr = region_at(i);
676 hr->set_continuesHumongous(first_hr);
677 hr->set_allocation_context(context);
678 }
679 // If we have "continues humongous" regions (hr != NULL), then the
680 // end of the last one should match new_end.
681 assert(hr == NULL || hr->end() == new_end, "sanity");
682
683 // Up to this point no concurrent thread would have been able to
684 // do any scanning on any region in this series. All the top
685 // fields still point to bottom, so the intersection between
686 // [bottom,top] and [card_start,card_end] will be empty. Before we
687 // update the top fields, we'll do a storestore to make sure that
688 // no thread sees the update to top before the zeroing of the
689 // object header and the BOT initialization.
690 OrderAccess::storestore();
691
692 // Now that the BOT and the object header have been initialized,
693 // we can update top of the "starts humongous" region.
694 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
695 "new_top should be in this region");
696 first_hr->set_top(new_top);
697 if (_hr_printer.is_active()) {
698 HeapWord* bottom = first_hr->bottom();
699 HeapWord* end = first_hr->orig_end();
700 if ((first + 1) == last) {
701 // the series has a single humongous region
702 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
703 } else {
704 // the series has more than one humongous regions
705 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
706 }
707 }
708
709 // Now, we will update the top fields of the "continues humongous"
710 // regions. The reason we need to do this is that, otherwise,
711 // these regions would look empty and this will confuse parts of
712 // G1. For example, the code that looks for a consecutive number
713 // of empty regions will consider them empty and try to
714 // re-allocate them. We can extend is_empty() to also include
715 // !continuesHumongous(), but it is easier to just update the top
716 // fields here. The way we set top for all regions (i.e., top ==
717 // end for all regions but the last one, top == new_top for the
718 // last one) is actually used when we will free up the humongous
719 // region in free_humongous_region().
720 hr = NULL;
721 for (uint i = first + 1; i < last; ++i) {
722 hr = region_at(i);
723 if ((i + 1) == last) {
724 // last continues humongous region
725 assert(hr->bottom() < new_top && new_top <= hr->end(),
726 "new_top should fall on this region");
727 hr->set_top(new_top);
728 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
729 } else {
730 // not last one
731 assert(new_top > hr->end(), "new_top should be above this region");
732 hr->set_top(hr->end());
733 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
734 }
735 }
736 // If we have continues humongous regions (hr != NULL), then the
737 // end of the last one should match new_end and its top should
738 // match new_top.
739 assert(hr == NULL ||
740 (hr->end() == new_end && hr->top() == new_top), "sanity");
741 check_bitmaps("Humongous Region Allocation", first_hr);
742
743 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
744 _allocator->increase_used(first_hr->used());
745 _humongous_set.add(first_hr);
746
747 return new_obj;
748 }
749
750 // If could fit into free regions w/o expansion, try.
751 // Otherwise, if can expand, do so.
752 // Otherwise, if using ex regions might help, try with ex given back.
753 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
754 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
755
756 verify_region_sets_optional();
757
758 uint first = G1_NO_HRM_INDEX;
759 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
760
761 if (obj_regions == 1) {
762 // Only one region to allocate, try to use a fast path by directly allocating
763 // from the free lists. Do not try to expand here, we will potentially do that
764 // later.
765 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
766 if (hr != NULL) {
767 first = hr->hrm_index();
768 }
769 } else {
770 // We can't allocate humongous regions spanning more than one region while
771 // cleanupComplete() is running, since some of the regions we find to be
772 // empty might not yet be added to the free list. It is not straightforward
773 // to know in which list they are on so that we can remove them. We only
774 // need to do this if we need to allocate more than one region to satisfy the
775 // current humongous allocation request. If we are only allocating one region
776 // we use the one-region region allocation code (see above), that already
777 // potentially waits for regions from the secondary free list.
778 wait_while_free_regions_coming();
779 append_secondary_free_list_if_not_empty_with_lock();
780
781 // Policy: Try only empty regions (i.e. already committed first). Maybe we
782 // are lucky enough to find some.
783 first = _hrm.find_contiguous_only_empty(obj_regions);
784 if (first != G1_NO_HRM_INDEX) {
785 _hrm.allocate_free_regions_starting_at(first, obj_regions);
786 }
787 }
788
789 if (first == G1_NO_HRM_INDEX) {
790 // Policy: We could not find enough regions for the humongous object in the
791 // free list. Look through the heap to find a mix of free and uncommitted regions.
792 // If so, try expansion.
793 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
794 if (first != G1_NO_HRM_INDEX) {
795 // We found something. Make sure these regions are committed, i.e. expand
796 // the heap. Alternatively we could do a defragmentation GC.
797 ergo_verbose1(ErgoHeapSizing,
798 "attempt heap expansion",
799 ergo_format_reason("humongous allocation request failed")
800 ergo_format_byte("allocation request"),
801 word_size * HeapWordSize);
802
803 _hrm.expand_at(first, obj_regions);
804 g1_policy()->record_new_heap_size(num_regions());
805
806 #ifdef ASSERT
807 for (uint i = first; i < first + obj_regions; ++i) {
808 HeapRegion* hr = region_at(i);
809 assert(hr->is_free(), "sanity");
810 assert(hr->is_empty(), "sanity");
811 assert(is_on_master_free_list(hr), "sanity");
812 }
813 #endif
814 _hrm.allocate_free_regions_starting_at(first, obj_regions);
815 } else {
816 // Policy: Potentially trigger a defragmentation GC.
817 }
818 }
819
820 HeapWord* result = NULL;
821 if (first != G1_NO_HRM_INDEX) {
822 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
823 word_size, context);
824 assert(result != NULL, "it should always return a valid result");
825
826 // A successful humongous object allocation changes the used space
827 // information of the old generation so we need to recalculate the
828 // sizes and update the jstat counters here.
829 g1mm()->update_sizes();
830 }
831
832 verify_region_sets_optional();
833
834 return result;
835 }
836
837 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
838 assert_heap_not_locked_and_not_at_safepoint();
839 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
840
841 unsigned int dummy_gc_count_before;
842 int dummy_gclocker_retry_count = 0;
843 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
844 }
845
846 HeapWord*
847 G1CollectedHeap::mem_allocate(size_t word_size,
848 bool* gc_overhead_limit_was_exceeded) {
849 assert_heap_not_locked_and_not_at_safepoint();
850
851 // Loop until the allocation is satisfied, or unsatisfied after GC.
852 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
853 unsigned int gc_count_before;
854
855 HeapWord* result = NULL;
856 if (!isHumongous(word_size)) {
857 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
858 } else {
859 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
860 }
861 if (result != NULL) {
862 return result;
863 }
864
865 // Create the garbage collection operation...
866 VM_G1CollectForAllocation op(gc_count_before, word_size);
867 op.set_allocation_context(AllocationContext::current());
868
869 // ...and get the VM thread to execute it.
870 VMThread::execute(&op);
871
872 if (op.prologue_succeeded() && op.pause_succeeded()) {
873 // If the operation was successful we'll return the result even
874 // if it is NULL. If the allocation attempt failed immediately
875 // after a Full GC, it's unlikely we'll be able to allocate now.
876 HeapWord* result = op.result();
877 if (result != NULL && !isHumongous(word_size)) {
878 // Allocations that take place on VM operations do not do any
879 // card dirtying and we have to do it here. We only have to do
880 // this for non-humongous allocations, though.
881 dirty_young_block(result, word_size);
882 }
883 return result;
884 } else {
885 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
886 return NULL;
887 }
888 assert(op.result() == NULL,
889 "the result should be NULL if the VM op did not succeed");
890 }
891
892 // Give a warning if we seem to be looping forever.
893 if ((QueuedAllocationWarningCount > 0) &&
894 (try_count % QueuedAllocationWarningCount == 0)) {
895 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
896 }
897 }
898
899 ShouldNotReachHere();
900 return NULL;
901 }
902
903 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
904 AllocationContext_t context,
905 unsigned int *gc_count_before_ret,
906 int* gclocker_retry_count_ret) {
907 // Make sure you read the note in attempt_allocation_humongous().
908
909 assert_heap_not_locked_and_not_at_safepoint();
910 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
911 "be called for humongous allocation requests");
912
913 // We should only get here after the first-level allocation attempt
914 // (attempt_allocation()) failed to allocate.
915
916 // We will loop until a) we manage to successfully perform the
917 // allocation or b) we successfully schedule a collection which
918 // fails to perform the allocation. b) is the only case when we'll
919 // return NULL.
920 HeapWord* result = NULL;
921 for (int try_count = 1; /* we'll return */; try_count += 1) {
922 bool should_try_gc;
923 unsigned int gc_count_before;
924
925 {
926 MutexLockerEx x(Heap_lock);
927 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
928 false /* bot_updates */);
929 if (result != NULL) {
930 return result;
931 }
932
933 // If we reach here, attempt_allocation_locked() above failed to
934 // allocate a new region. So the mutator alloc region should be NULL.
935 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
936
937 if (GC_locker::is_active_and_needs_gc()) {
938 if (g1_policy()->can_expand_young_list()) {
939 // No need for an ergo verbose message here,
940 // can_expand_young_list() does this when it returns true.
941 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
942 false /* bot_updates */);
943 if (result != NULL) {
944 return result;
945 }
946 }
947 should_try_gc = false;
948 } else {
949 // The GCLocker may not be active but the GCLocker initiated
950 // GC may not yet have been performed (GCLocker::needs_gc()
951 // returns true). In this case we do not try this GC and
952 // wait until the GCLocker initiated GC is performed, and
953 // then retry the allocation.
954 if (GC_locker::needs_gc()) {
955 should_try_gc = false;
956 } else {
957 // Read the GC count while still holding the Heap_lock.
958 gc_count_before = total_collections();
959 should_try_gc = true;
960 }
961 }
962 }
963
964 if (should_try_gc) {
965 bool succeeded;
966 result = do_collection_pause(word_size, gc_count_before, &succeeded,
967 GCCause::_g1_inc_collection_pause);
968 if (result != NULL) {
969 assert(succeeded, "only way to get back a non-NULL result");
970 return result;
971 }
972
973 if (succeeded) {
974 // If we get here we successfully scheduled a collection which
975 // failed to allocate. No point in trying to allocate
976 // further. We'll just return NULL.
977 MutexLockerEx x(Heap_lock);
978 *gc_count_before_ret = total_collections();
979 return NULL;
980 }
981 } else {
982 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
983 MutexLockerEx x(Heap_lock);
984 *gc_count_before_ret = total_collections();
985 return NULL;
986 }
987 // The GCLocker is either active or the GCLocker initiated
988 // GC has not yet been performed. Stall until it is and
989 // then retry the allocation.
990 GC_locker::stall_until_clear();
991 (*gclocker_retry_count_ret) += 1;
992 }
993
994 // We can reach here if we were unsuccessful in scheduling a
995 // collection (because another thread beat us to it) or if we were
996 // stalled due to the GC locker. In either can we should retry the
997 // allocation attempt in case another thread successfully
998 // performed a collection and reclaimed enough space. We do the
999 // first attempt (without holding the Heap_lock) here and the
1000 // follow-on attempt will be at the start of the next loop
1001 // iteration (after taking the Heap_lock).
1002 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
1003 false /* bot_updates */);
1004 if (result != NULL) {
1005 return result;
1006 }
1007
1008 // Give a warning if we seem to be looping forever.
1009 if ((QueuedAllocationWarningCount > 0) &&
1010 (try_count % QueuedAllocationWarningCount == 0)) {
1011 warning("G1CollectedHeap::attempt_allocation_slow() "
1012 "retries %d times", try_count);
1013 }
1014 }
1015
1016 ShouldNotReachHere();
1017 return NULL;
1018 }
1019
1020 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1021 unsigned int * gc_count_before_ret,
1022 int* gclocker_retry_count_ret) {
1023 // The structure of this method has a lot of similarities to
1024 // attempt_allocation_slow(). The reason these two were not merged
1025 // into a single one is that such a method would require several "if
1026 // allocation is not humongous do this, otherwise do that"
1027 // conditional paths which would obscure its flow. In fact, an early
1028 // version of this code did use a unified method which was harder to
1029 // follow and, as a result, it had subtle bugs that were hard to
1030 // track down. So keeping these two methods separate allows each to
1031 // be more readable. It will be good to keep these two in sync as
1032 // much as possible.
1033
1034 assert_heap_not_locked_and_not_at_safepoint();
1035 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1036 "should only be called for humongous allocations");
1037
1038 // Humongous objects can exhaust the heap quickly, so we should check if we
1039 // need to start a marking cycle at each humongous object allocation. We do
1040 // the check before we do the actual allocation. The reason for doing it
1041 // before the allocation is that we avoid having to keep track of the newly
1042 // allocated memory while we do a GC.
1043 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1044 word_size)) {
1045 collect(GCCause::_g1_humongous_allocation);
1046 }
1047
1048 // We will loop until a) we manage to successfully perform the
1049 // allocation or b) we successfully schedule a collection which
1050 // fails to perform the allocation. b) is the only case when we'll
1051 // return NULL.
1052 HeapWord* result = NULL;
1053 for (int try_count = 1; /* we'll return */; try_count += 1) {
1054 bool should_try_gc;
1055 unsigned int gc_count_before;
1056
1057 {
1058 MutexLockerEx x(Heap_lock);
1059
1060 // Given that humongous objects are not allocated in young
1061 // regions, we'll first try to do the allocation without doing a
1062 // collection hoping that there's enough space in the heap.
1063 result = humongous_obj_allocate(word_size, AllocationContext::current());
1064 if (result != NULL) {
1065 return result;
1066 }
1067
1068 if (GC_locker::is_active_and_needs_gc()) {
1069 should_try_gc = false;
1070 } else {
1071 // The GCLocker may not be active but the GCLocker initiated
1072 // GC may not yet have been performed (GCLocker::needs_gc()
1073 // returns true). In this case we do not try this GC and
1074 // wait until the GCLocker initiated GC is performed, and
1075 // then retry the allocation.
1076 if (GC_locker::needs_gc()) {
1077 should_try_gc = false;
1078 } else {
1079 // Read the GC count while still holding the Heap_lock.
1080 gc_count_before = total_collections();
1081 should_try_gc = true;
1082 }
1083 }
1084 }
1085
1086 if (should_try_gc) {
1087 // If we failed to allocate the humongous object, we should try to
1088 // do a collection pause (if we're allowed) in case it reclaims
1089 // enough space for the allocation to succeed after the pause.
1090
1091 bool succeeded;
1092 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1093 GCCause::_g1_humongous_allocation);
1094 if (result != NULL) {
1095 assert(succeeded, "only way to get back a non-NULL result");
1096 return result;
1097 }
1098
1099 if (succeeded) {
1100 // If we get here we successfully scheduled a collection which
1101 // failed to allocate. No point in trying to allocate
1102 // further. We'll just return NULL.
1103 MutexLockerEx x(Heap_lock);
1104 *gc_count_before_ret = total_collections();
1105 return NULL;
1106 }
1107 } else {
1108 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1109 MutexLockerEx x(Heap_lock);
1110 *gc_count_before_ret = total_collections();
1111 return NULL;
1112 }
1113 // The GCLocker is either active or the GCLocker initiated
1114 // GC has not yet been performed. Stall until it is and
1115 // then retry the allocation.
1116 GC_locker::stall_until_clear();
1117 (*gclocker_retry_count_ret) += 1;
1118 }
1119
1120 // We can reach here if we were unsuccessful in scheduling a
1121 // collection (because another thread beat us to it) or if we were
1122 // stalled due to the GC locker. In either can we should retry the
1123 // allocation attempt in case another thread successfully
1124 // performed a collection and reclaimed enough space. Give a
1125 // warning if we seem to be looping forever.
1126
1127 if ((QueuedAllocationWarningCount > 0) &&
1128 (try_count % QueuedAllocationWarningCount == 0)) {
1129 warning("G1CollectedHeap::attempt_allocation_humongous() "
1130 "retries %d times", try_count);
1131 }
1132 }
1133
1134 ShouldNotReachHere();
1135 return NULL;
1136 }
1137
1138 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1139 AllocationContext_t context,
1140 bool expect_null_mutator_alloc_region) {
1141 assert_at_safepoint(true /* should_be_vm_thread */);
1142 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1143 !expect_null_mutator_alloc_region,
1144 "the current alloc region was unexpectedly found to be non-NULL");
1145
1146 if (!isHumongous(word_size)) {
1147 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1148 false /* bot_updates */);
1149 } else {
1150 HeapWord* result = humongous_obj_allocate(word_size, context);
1151 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1152 g1_policy()->set_initiate_conc_mark_if_possible();
1153 }
1154 return result;
1155 }
1156
1157 ShouldNotReachHere();
1158 }
1159
1160 class PostMCRemSetClearClosure: public HeapRegionClosure {
1161 G1CollectedHeap* _g1h;
1162 ModRefBarrierSet* _mr_bs;
1163 public:
1164 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1165 _g1h(g1h), _mr_bs(mr_bs) {}
1166
1167 bool doHeapRegion(HeapRegion* r) {
1168 HeapRegionRemSet* hrrs = r->rem_set();
1169
1170 if (r->continuesHumongous()) {
1171 // We'll assert that the strong code root list and RSet is empty
1172 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1173 assert(hrrs->occupied() == 0, "RSet should be empty");
1174 return false;
1175 }
1176
1177 _g1h->reset_gc_time_stamps(r);
1178 hrrs->clear();
1179 // You might think here that we could clear just the cards
1180 // corresponding to the used region. But no: if we leave a dirty card
1181 // in a region we might allocate into, then it would prevent that card
1182 // from being enqueued, and cause it to be missed.
1183 // Re: the performance cost: we shouldn't be doing full GC anyway!
1184 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1185
1186 return false;
1187 }
1188 };
1189
1190 void G1CollectedHeap::clear_rsets_post_compaction() {
1191 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1192 heap_region_iterate(&rs_clear);
1193 }
1194
1195 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1196 G1CollectedHeap* _g1h;
1197 UpdateRSOopClosure _cl;
1198 int _worker_i;
1199 public:
1200 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1201 _cl(g1->g1_rem_set(), worker_i),
1202 _worker_i(worker_i),
1203 _g1h(g1)
1204 { }
1205
1206 bool doHeapRegion(HeapRegion* r) {
1207 if (!r->continuesHumongous()) {
1208 _cl.set_from(r);
1209 r->oop_iterate(&_cl);
1210 }
1211 return false;
1212 }
1213 };
1214
1215 class ParRebuildRSTask: public AbstractGangTask {
1216 G1CollectedHeap* _g1;
1217 public:
1218 ParRebuildRSTask(G1CollectedHeap* g1)
1219 : AbstractGangTask("ParRebuildRSTask"),
1220 _g1(g1)
1221 { }
1222
1223 void work(uint worker_id) {
1224 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1225 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1226 _g1->workers()->active_workers(),
1227 HeapRegion::RebuildRSClaimValue);
1228 }
1229 };
1230
1231 class PostCompactionPrinterClosure: public HeapRegionClosure {
1232 private:
1233 G1HRPrinter* _hr_printer;
1234 public:
1235 bool doHeapRegion(HeapRegion* hr) {
1236 assert(!hr->is_young(), "not expecting to find young regions");
1237 if (hr->is_free()) {
1238 // We only generate output for non-empty regions.
1239 } else if (hr->startsHumongous()) {
1240 if (hr->region_num() == 1) {
1241 // single humongous region
1242 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1243 } else {
1244 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1245 }
1246 } else if (hr->continuesHumongous()) {
1247 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1248 } else if (hr->is_old()) {
1249 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1250 } else {
1251 ShouldNotReachHere();
1252 }
1253 return false;
1254 }
1255
1256 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1257 : _hr_printer(hr_printer) { }
1258 };
1259
1260 void G1CollectedHeap::print_hrm_post_compaction() {
1261 PostCompactionPrinterClosure cl(hr_printer());
1262 heap_region_iterate(&cl);
1263 }
1264
1265 bool G1CollectedHeap::do_collection(bool explicit_gc,
1266 bool clear_all_soft_refs,
1267 size_t word_size) {
1268 assert_at_safepoint(true /* should_be_vm_thread */);
1269
1270 if (GC_locker::check_active_before_gc()) {
1271 return false;
1272 }
1273
1274 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1275 gc_timer->register_gc_start();
1276
1277 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1278 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1279
1280 SvcGCMarker sgcm(SvcGCMarker::FULL);
1281 ResourceMark rm;
1282
1283 print_heap_before_gc();
1284 trace_heap_before_gc(gc_tracer);
1285
1286 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1287
1288 verify_region_sets_optional();
1289
1290 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1291 collector_policy()->should_clear_all_soft_refs();
1292
1293 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1294
1295 {
1296 IsGCActiveMark x;
1297
1298 // Timing
1299 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1300 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1301 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1302
1303 {
1304 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1305 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1306 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1307
1308 double start = os::elapsedTime();
1309 g1_policy()->record_full_collection_start();
1310
1311 // Note: When we have a more flexible GC logging framework that
1312 // allows us to add optional attributes to a GC log record we
1313 // could consider timing and reporting how long we wait in the
1314 // following two methods.
1315 wait_while_free_regions_coming();
1316 // If we start the compaction before the CM threads finish
1317 // scanning the root regions we might trip them over as we'll
1318 // be moving objects / updating references. So let's wait until
1319 // they are done. By telling them to abort, they should complete
1320 // early.
1321 _cm->root_regions()->abort();
1322 _cm->root_regions()->wait_until_scan_finished();
1323 append_secondary_free_list_if_not_empty_with_lock();
1324
1325 gc_prologue(true);
1326 increment_total_collections(true /* full gc */);
1327 increment_old_marking_cycles_started();
1328
1329 assert(used() == recalculate_used(), "Should be equal");
1330
1331 verify_before_gc();
1332
1333 check_bitmaps("Full GC Start");
1334 pre_full_gc_dump(gc_timer);
1335
1336 COMPILER2_PRESENT(DerivedPointerTable::clear());
1337
1338 // Disable discovery and empty the discovered lists
1339 // for the CM ref processor.
1340 ref_processor_cm()->disable_discovery();
1341 ref_processor_cm()->abandon_partial_discovery();
1342 ref_processor_cm()->verify_no_references_recorded();
1343
1344 // Abandon current iterations of concurrent marking and concurrent
1345 // refinement, if any are in progress. We have to do this before
1346 // wait_until_scan_finished() below.
1347 concurrent_mark()->abort();
1348
1349 // Make sure we'll choose a new allocation region afterwards.
1350 _allocator->release_mutator_alloc_region();
1351 _allocator->abandon_gc_alloc_regions();
1352 g1_rem_set()->cleanupHRRS();
1353
1354 // We should call this after we retire any currently active alloc
1355 // regions so that all the ALLOC / RETIRE events are generated
1356 // before the start GC event.
1357 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1358
1359 // We may have added regions to the current incremental collection
1360 // set between the last GC or pause and now. We need to clear the
1361 // incremental collection set and then start rebuilding it afresh
1362 // after this full GC.
1363 abandon_collection_set(g1_policy()->inc_cset_head());
1364 g1_policy()->clear_incremental_cset();
1365 g1_policy()->stop_incremental_cset_building();
1366
1367 tear_down_region_sets(false /* free_list_only */);
1368 g1_policy()->set_gcs_are_young(true);
1369
1370 // See the comments in g1CollectedHeap.hpp and
1371 // G1CollectedHeap::ref_processing_init() about
1372 // how reference processing currently works in G1.
1373
1374 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1375 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1376
1377 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1378 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1379
1380 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1381 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1382
1383 // Do collection work
1384 {
1385 HandleMark hm; // Discard invalid handles created during gc
1386 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1387 }
1388
1389 assert(num_free_regions() == 0, "we should not have added any free regions");
1390 rebuild_region_sets(false /* free_list_only */);
1391
1392 // Enqueue any discovered reference objects that have
1393 // not been removed from the discovered lists.
1394 ref_processor_stw()->enqueue_discovered_references();
1395
1396 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1397
1398 MemoryService::track_memory_usage();
1399
1400 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1401 ref_processor_stw()->verify_no_references_recorded();
1402
1403 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1404 ClassLoaderDataGraph::purge();
1405 MetaspaceAux::verify_metrics();
1406
1407 // Note: since we've just done a full GC, concurrent
1408 // marking is no longer active. Therefore we need not
1409 // re-enable reference discovery for the CM ref processor.
1410 // That will be done at the start of the next marking cycle.
1411 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1412 ref_processor_cm()->verify_no_references_recorded();
1413
1414 reset_gc_time_stamp();
1415 // Since everything potentially moved, we will clear all remembered
1416 // sets, and clear all cards. Later we will rebuild remembered
1417 // sets. We will also reset the GC time stamps of the regions.
1418 clear_rsets_post_compaction();
1419 check_gc_time_stamps();
1420
1421 // Resize the heap if necessary.
1422 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1423
1424 if (_hr_printer.is_active()) {
1425 // We should do this after we potentially resize the heap so
1426 // that all the COMMIT / UNCOMMIT events are generated before
1427 // the end GC event.
1428
1429 print_hrm_post_compaction();
1430 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1431 }
1432
1433 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1434 if (hot_card_cache->use_cache()) {
1435 hot_card_cache->reset_card_counts();
1436 hot_card_cache->reset_hot_cache();
1437 }
1438
1439 // Rebuild remembered sets of all regions.
1440 if (G1CollectedHeap::use_parallel_gc_threads()) {
1441 uint n_workers =
1442 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1443 workers()->active_workers(),
1444 Threads::number_of_non_daemon_threads());
1445 assert(UseDynamicNumberOfGCThreads ||
1446 n_workers == workers()->total_workers(),
1447 "If not dynamic should be using all the workers");
1448 workers()->set_active_workers(n_workers);
1449 // Set parallel threads in the heap (_n_par_threads) only
1450 // before a parallel phase and always reset it to 0 after
1451 // the phase so that the number of parallel threads does
1452 // no get carried forward to a serial phase where there
1453 // may be code that is "possibly_parallel".
1454 set_par_threads(n_workers);
1455
1456 ParRebuildRSTask rebuild_rs_task(this);
1457 assert(check_heap_region_claim_values(
1458 HeapRegion::InitialClaimValue), "sanity check");
1459 assert(UseDynamicNumberOfGCThreads ||
1460 workers()->active_workers() == workers()->total_workers(),
1461 "Unless dynamic should use total workers");
1462 // Use the most recent number of active workers
1463 assert(workers()->active_workers() > 0,
1464 "Active workers not properly set");
1465 set_par_threads(workers()->active_workers());
1466 workers()->run_task(&rebuild_rs_task);
1467 set_par_threads(0);
1468 assert(check_heap_region_claim_values(
1469 HeapRegion::RebuildRSClaimValue), "sanity check");
1470 reset_heap_region_claim_values();
1471 } else {
1472 RebuildRSOutOfRegionClosure rebuild_rs(this);
1473 heap_region_iterate(&rebuild_rs);
1474 }
1475
1476 // Rebuild the strong code root lists for each region
1477 rebuild_strong_code_roots();
1478
1479 if (true) { // FIXME
1480 MetaspaceGC::compute_new_size();
1481 }
1482
1483 #ifdef TRACESPINNING
1484 ParallelTaskTerminator::print_termination_counts();
1485 #endif
1486
1487 // Discard all rset updates
1488 JavaThread::dirty_card_queue_set().abandon_logs();
1489 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1490
1491 _young_list->reset_sampled_info();
1492 // At this point there should be no regions in the
1493 // entire heap tagged as young.
1494 assert(check_young_list_empty(true /* check_heap */),
1495 "young list should be empty at this point");
1496
1497 // Update the number of full collections that have been completed.
1498 increment_old_marking_cycles_completed(false /* concurrent */);
1499
1500 _hrm.verify_optional();
1501 verify_region_sets_optional();
1502
1503 verify_after_gc();
1504
1505 // Clear the previous marking bitmap, if needed for bitmap verification.
1506 // Note we cannot do this when we clear the next marking bitmap in
1507 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1508 // objects marked during a full GC against the previous bitmap.
1509 // But we need to clear it before calling check_bitmaps below since
1510 // the full GC has compacted objects and updated TAMS but not updated
1511 // the prev bitmap.
1512 if (G1VerifyBitmaps) {
1513 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1514 }
1515 check_bitmaps("Full GC End");
1516
1517 // Start a new incremental collection set for the next pause
1518 assert(g1_policy()->collection_set() == NULL, "must be");
1519 g1_policy()->start_incremental_cset_building();
1520
1521 clear_cset_fast_test();
1522
1523 _allocator->init_mutator_alloc_region();
1524
1525 double end = os::elapsedTime();
1526 g1_policy()->record_full_collection_end();
1527
1528 if (G1Log::fine()) {
1529 g1_policy()->print_heap_transition();
1530 }
1531
1532 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1533 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1534 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1535 // before any GC notifications are raised.
1536 g1mm()->update_sizes();
1537
1538 gc_epilogue(true);
1539 }
1540
1541 if (G1Log::finer()) {
1542 g1_policy()->print_detailed_heap_transition(true /* full */);
1543 }
1544
1545 print_heap_after_gc();
1546 trace_heap_after_gc(gc_tracer);
1547
1548 post_full_gc_dump(gc_timer);
1549
1550 gc_timer->register_gc_end();
1551 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1552 }
1553
1554 return true;
1555 }
1556
1557 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1558 // do_collection() will return whether it succeeded in performing
1559 // the GC. Currently, there is no facility on the
1560 // do_full_collection() API to notify the caller than the collection
1561 // did not succeed (e.g., because it was locked out by the GC
1562 // locker). So, right now, we'll ignore the return value.
1563 bool dummy = do_collection(true, /* explicit_gc */
1564 clear_all_soft_refs,
1565 0 /* word_size */);
1566 }
1567
1568 // This code is mostly copied from TenuredGeneration.
1569 void
1570 G1CollectedHeap::
1571 resize_if_necessary_after_full_collection(size_t word_size) {
1572 // Include the current allocation, if any, and bytes that will be
1573 // pre-allocated to support collections, as "used".
1574 const size_t used_after_gc = used();
1575 const size_t capacity_after_gc = capacity();
1576 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1577
1578 // This is enforced in arguments.cpp.
1579 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1580 "otherwise the code below doesn't make sense");
1581
1582 // We don't have floating point command-line arguments
1583 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1584 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1585 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1586 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1587
1588 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1589 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1590
1591 // We have to be careful here as these two calculations can overflow
1592 // 32-bit size_t's.
1593 double used_after_gc_d = (double) used_after_gc;
1594 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1595 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1596
1597 // Let's make sure that they are both under the max heap size, which
1598 // by default will make them fit into a size_t.
1599 double desired_capacity_upper_bound = (double) max_heap_size;
1600 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1601 desired_capacity_upper_bound);
1602 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1603 desired_capacity_upper_bound);
1604
1605 // We can now safely turn them into size_t's.
1606 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1607 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1608
1609 // This assert only makes sense here, before we adjust them
1610 // with respect to the min and max heap size.
1611 assert(minimum_desired_capacity <= maximum_desired_capacity,
1612 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1613 "maximum_desired_capacity = "SIZE_FORMAT,
1614 minimum_desired_capacity, maximum_desired_capacity));
1615
1616 // Should not be greater than the heap max size. No need to adjust
1617 // it with respect to the heap min size as it's a lower bound (i.e.,
1618 // we'll try to make the capacity larger than it, not smaller).
1619 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1620 // Should not be less than the heap min size. No need to adjust it
1621 // with respect to the heap max size as it's an upper bound (i.e.,
1622 // we'll try to make the capacity smaller than it, not greater).
1623 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1624
1625 if (capacity_after_gc < minimum_desired_capacity) {
1626 // Don't expand unless it's significant
1627 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1628 ergo_verbose4(ErgoHeapSizing,
1629 "attempt heap expansion",
1630 ergo_format_reason("capacity lower than "
1631 "min desired capacity after Full GC")
1632 ergo_format_byte("capacity")
1633 ergo_format_byte("occupancy")
1634 ergo_format_byte_perc("min desired capacity"),
1635 capacity_after_gc, used_after_gc,
1636 minimum_desired_capacity, (double) MinHeapFreeRatio);
1637 expand(expand_bytes);
1638
1639 // No expansion, now see if we want to shrink
1640 } else if (capacity_after_gc > maximum_desired_capacity) {
1641 // Capacity too large, compute shrinking size
1642 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1643 ergo_verbose4(ErgoHeapSizing,
1644 "attempt heap shrinking",
1645 ergo_format_reason("capacity higher than "
1646 "max desired capacity after Full GC")
1647 ergo_format_byte("capacity")
1648 ergo_format_byte("occupancy")
1649 ergo_format_byte_perc("max desired capacity"),
1650 capacity_after_gc, used_after_gc,
1651 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1652 shrink(shrink_bytes);
1653 }
1654 }
1655
1656
1657 HeapWord*
1658 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1659 AllocationContext_t context,
1660 bool* succeeded) {
1661 assert_at_safepoint(true /* should_be_vm_thread */);
1662
1663 *succeeded = true;
1664 // Let's attempt the allocation first.
1665 HeapWord* result =
1666 attempt_allocation_at_safepoint(word_size,
1667 context,
1668 false /* expect_null_mutator_alloc_region */);
1669 if (result != NULL) {
1670 assert(*succeeded, "sanity");
1671 return result;
1672 }
1673
1674 // In a G1 heap, we're supposed to keep allocation from failing by
1675 // incremental pauses. Therefore, at least for now, we'll favor
1676 // expansion over collection. (This might change in the future if we can
1677 // do something smarter than full collection to satisfy a failed alloc.)
1678 result = expand_and_allocate(word_size, context);
1679 if (result != NULL) {
1680 assert(*succeeded, "sanity");
1681 return result;
1682 }
1683
1684 // Expansion didn't work, we'll try to do a Full GC.
1685 bool gc_succeeded = do_collection(false, /* explicit_gc */
1686 false, /* clear_all_soft_refs */
1687 word_size);
1688 if (!gc_succeeded) {
1689 *succeeded = false;
1690 return NULL;
1691 }
1692
1693 // Retry the allocation
1694 result = attempt_allocation_at_safepoint(word_size,
1695 context,
1696 true /* expect_null_mutator_alloc_region */);
1697 if (result != NULL) {
1698 assert(*succeeded, "sanity");
1699 return result;
1700 }
1701
1702 // Then, try a Full GC that will collect all soft references.
1703 gc_succeeded = do_collection(false, /* explicit_gc */
1704 true, /* clear_all_soft_refs */
1705 word_size);
1706 if (!gc_succeeded) {
1707 *succeeded = false;
1708 return NULL;
1709 }
1710
1711 // Retry the allocation once more
1712 result = attempt_allocation_at_safepoint(word_size,
1713 context,
1714 true /* expect_null_mutator_alloc_region */);
1715 if (result != NULL) {
1716 assert(*succeeded, "sanity");
1717 return result;
1718 }
1719
1720 assert(!collector_policy()->should_clear_all_soft_refs(),
1721 "Flag should have been handled and cleared prior to this point");
1722
1723 // What else? We might try synchronous finalization later. If the total
1724 // space available is large enough for the allocation, then a more
1725 // complete compaction phase than we've tried so far might be
1726 // appropriate.
1727 assert(*succeeded, "sanity");
1728 return NULL;
1729 }
1730
1731 // Attempting to expand the heap sufficiently
1732 // to support an allocation of the given "word_size". If
1733 // successful, perform the allocation and return the address of the
1734 // allocated block, or else "NULL".
1735
1736 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1737 assert_at_safepoint(true /* should_be_vm_thread */);
1738
1739 verify_region_sets_optional();
1740
1741 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1742 ergo_verbose1(ErgoHeapSizing,
1743 "attempt heap expansion",
1744 ergo_format_reason("allocation request failed")
1745 ergo_format_byte("allocation request"),
1746 word_size * HeapWordSize);
1747 if (expand(expand_bytes)) {
1748 _hrm.verify_optional();
1749 verify_region_sets_optional();
1750 return attempt_allocation_at_safepoint(word_size,
1751 context,
1752 false /* expect_null_mutator_alloc_region */);
1753 }
1754 return NULL;
1755 }
1756
1757 bool G1CollectedHeap::expand(size_t expand_bytes) {
1758 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1759 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1760 HeapRegion::GrainBytes);
1761 ergo_verbose2(ErgoHeapSizing,
1762 "expand the heap",
1763 ergo_format_byte("requested expansion amount")
1764 ergo_format_byte("attempted expansion amount"),
1765 expand_bytes, aligned_expand_bytes);
1766
1767 if (is_maximal_no_gc()) {
1768 ergo_verbose0(ErgoHeapSizing,
1769 "did not expand the heap",
1770 ergo_format_reason("heap already fully expanded"));
1771 return false;
1772 }
1773
1774 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1775 assert(regions_to_expand > 0, "Must expand by at least one region");
1776
1777 uint expanded_by = _hrm.expand_by(regions_to_expand);
1778
1779 if (expanded_by > 0) {
1780 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1781 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1782 g1_policy()->record_new_heap_size(num_regions());
1783 } else {
1784 ergo_verbose0(ErgoHeapSizing,
1785 "did not expand the heap",
1786 ergo_format_reason("heap expansion operation failed"));
1787 // The expansion of the virtual storage space was unsuccessful.
1788 // Let's see if it was because we ran out of swap.
1789 if (G1ExitOnExpansionFailure &&
1790 _hrm.available() >= regions_to_expand) {
1791 // We had head room...
1792 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1793 }
1794 }
1795 return regions_to_expand > 0;
1796 }
1797
1798 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1799 size_t aligned_shrink_bytes =
1800 ReservedSpace::page_align_size_down(shrink_bytes);
1801 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1802 HeapRegion::GrainBytes);
1803 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1804
1805 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1806 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1807
1808 ergo_verbose3(ErgoHeapSizing,
1809 "shrink the heap",
1810 ergo_format_byte("requested shrinking amount")
1811 ergo_format_byte("aligned shrinking amount")
1812 ergo_format_byte("attempted shrinking amount"),
1813 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1814 if (num_regions_removed > 0) {
1815 g1_policy()->record_new_heap_size(num_regions());
1816 } else {
1817 ergo_verbose0(ErgoHeapSizing,
1818 "did not shrink the heap",
1819 ergo_format_reason("heap shrinking operation failed"));
1820 }
1821 }
1822
1823 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1824 verify_region_sets_optional();
1825
1826 // We should only reach here at the end of a Full GC which means we
1827 // should not not be holding to any GC alloc regions. The method
1828 // below will make sure of that and do any remaining clean up.
1829 _allocator->abandon_gc_alloc_regions();
1830
1831 // Instead of tearing down / rebuilding the free lists here, we
1832 // could instead use the remove_all_pending() method on free_list to
1833 // remove only the ones that we need to remove.
1834 tear_down_region_sets(true /* free_list_only */);
1835 shrink_helper(shrink_bytes);
1836 rebuild_region_sets(true /* free_list_only */);
1837
1838 _hrm.verify_optional();
1839 verify_region_sets_optional();
1840 }
1841
1842 // Public methods.
1843
1844 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1845 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1846 #endif // _MSC_VER
1847
1848
1849 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1850 SharedHeap(policy_),
1851 _g1_policy(policy_),
1852 _dirty_card_queue_set(false),
1853 _into_cset_dirty_card_queue_set(false),
1854 _is_alive_closure_cm(this),
1855 _is_alive_closure_stw(this),
1856 _ref_processor_cm(NULL),
1857 _ref_processor_stw(NULL),
1858 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1859 _bot_shared(NULL),
1860 _evac_failure_scan_stack(NULL),
1861 _mark_in_progress(false),
1862 _cg1r(NULL),
1863 _g1mm(NULL),
1864 _refine_cte_cl(NULL),
1865 _full_collection(false),
1866 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1867 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1868 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1869 _humongous_is_live(),
1870 _has_humongous_reclaim_candidates(false),
1871 _free_regions_coming(false),
1872 _young_list(new YoungList(this)),
1873 _gc_time_stamp(0),
1874 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1875 _old_plab_stats(OldPLABSize, PLABWeight),
1876 _expand_heap_after_alloc_failure(true),
1877 _surviving_young_words(NULL),
1878 _old_marking_cycles_started(0),
1879 _old_marking_cycles_completed(0),
1880 _concurrent_cycle_started(false),
1881 _in_cset_fast_test(),
1882 _dirty_cards_region_list(NULL),
1883 _worker_cset_start_region(NULL),
1884 _worker_cset_start_region_time_stamp(NULL),
1885 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1886 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1887 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1888 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1889
1890 _g1h = this;
1891 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1892 vm_exit_during_initialization("Failed necessary allocation.");
1893 }
1894
1895 _allocator = G1Allocator::create_allocator(_g1h);
1896 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1897
1898 int n_queues = MAX2((int)ParallelGCThreads, 1);
1899 _task_queues = new RefToScanQueueSet(n_queues);
1900
1901 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1902 assert(n_rem_sets > 0, "Invariant.");
1903
1904 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1905 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1906 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1907
1908 for (int i = 0; i < n_queues; i++) {
1909 RefToScanQueue* q = new RefToScanQueue();
1910 q->initialize();
1911 _task_queues->register_queue(i, q);
1912 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1913 }
1914 clear_cset_start_regions();
1915
1916 // Initialize the G1EvacuationFailureALot counters and flags.
1917 NOT_PRODUCT(reset_evacuation_should_fail();)
1918
1919 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1920 }
1921
1922 jint G1CollectedHeap::initialize() {
1923 CollectedHeap::pre_initialize();
1924 os::enable_vtime();
1925
1926 G1Log::init();
1927
1928 // Necessary to satisfy locking discipline assertions.
1929
1930 MutexLocker x(Heap_lock);
1931
1932 // We have to initialize the printer before committing the heap, as
1933 // it will be used then.
1934 _hr_printer.set_active(G1PrintHeapRegions);
1935
1936 // While there are no constraints in the GC code that HeapWordSize
1937 // be any particular value, there are multiple other areas in the
1938 // system which believe this to be true (e.g. oop->object_size in some
1939 // cases incorrectly returns the size in wordSize units rather than
1940 // HeapWordSize).
1941 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1942
1943 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1944 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1945 size_t heap_alignment = collector_policy()->heap_alignment();
1946
1947 // Ensure that the sizes are properly aligned.
1948 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1949 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1950 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1951
1952 _refine_cte_cl = new RefineCardTableEntryClosure();
1953
1954 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1955
1956 // Reserve the maximum.
1957
1958 // When compressed oops are enabled, the preferred heap base
1959 // is calculated by subtracting the requested size from the
1960 // 32Gb boundary and using the result as the base address for
1961 // heap reservation. If the requested size is not aligned to
1962 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1963 // into the ReservedHeapSpace constructor) then the actual
1964 // base of the reserved heap may end up differing from the
1965 // address that was requested (i.e. the preferred heap base).
1966 // If this happens then we could end up using a non-optimal
1967 // compressed oops mode.
1968
1969 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1970 heap_alignment);
1971
1972 // It is important to do this in a way such that concurrent readers can't
1973 // temporarily think something is in the heap. (I've actually seen this
1974 // happen in asserts: DLD.)
1975 _reserved.set_word_size(0);
1976 _reserved.set_start((HeapWord*)heap_rs.base());
1977 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1978
1979 // Create the gen rem set (and barrier set) for the entire reserved region.
1980 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1981 set_barrier_set(rem_set()->bs());
1982 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1983 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1984 return JNI_ENOMEM;
1985 }
1986
1987 // Also create a G1 rem set.
1988 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1989
1990 // Carve out the G1 part of the heap.
1991
1992 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1993 G1RegionToSpaceMapper* heap_storage =
1994 G1RegionToSpaceMapper::create_mapper(g1_rs,
1995 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1996 HeapRegion::GrainBytes,
1997 1,
1998 mtJavaHeap);
1999 heap_storage->set_mapping_changed_listener(&_listener);
2000
2001 // Reserve space for the block offset table. We do not support automatic uncommit
2002 // for the card table at this time. BOT only.
2003 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
2004 G1RegionToSpaceMapper* bot_storage =
2005 G1RegionToSpaceMapper::create_mapper(bot_rs,
2006 os::vm_page_size(),
2007 HeapRegion::GrainBytes,
2008 G1BlockOffsetSharedArray::N_bytes,
2009 mtGC);
2010
2011 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2012 G1RegionToSpaceMapper* cardtable_storage =
2013 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
2014 os::vm_page_size(),
2015 HeapRegion::GrainBytes,
2016 G1BlockOffsetSharedArray::N_bytes,
2017 mtGC);
2018
2019 // Reserve space for the card counts table.
2020 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
2021 G1RegionToSpaceMapper* card_counts_storage =
2022 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
2023 os::vm_page_size(),
2024 HeapRegion::GrainBytes,
2025 G1BlockOffsetSharedArray::N_bytes,
2026 mtGC);
2027
2028 // Reserve space for prev and next bitmap.
2029 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2030
2031 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2032 G1RegionToSpaceMapper* prev_bitmap_storage =
2033 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
2034 os::vm_page_size(),
2035 HeapRegion::GrainBytes,
2036 CMBitMap::mark_distance(),
2037 mtGC);
2038
2039 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2040 G1RegionToSpaceMapper* next_bitmap_storage =
2041 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
2042 os::vm_page_size(),
2043 HeapRegion::GrainBytes,
2044 CMBitMap::mark_distance(),
2045 mtGC);
2046
2047 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2048 g1_barrier_set()->initialize(cardtable_storage);
2049 // Do later initialization work for concurrent refinement.
2050 _cg1r->init(card_counts_storage);
2051
2052 // 6843694 - ensure that the maximum region index can fit
2053 // in the remembered set structures.
2054 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2055 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2056
2057 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2058 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2059 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2060 "too many cards per region");
2061
2062 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2063
2064 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
2065
2066 _g1h = this;
2067
2068 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2069 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2070
2071 // Create the ConcurrentMark data structure and thread.
2072 // (Must do this late, so that "max_regions" is defined.)
2073 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2074 if (_cm == NULL || !_cm->completed_initialization()) {
2075 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2076 return JNI_ENOMEM;
2077 }
2078 _cmThread = _cm->cmThread();
2079
2080 // Initialize the from_card cache structure of HeapRegionRemSet.
2081 HeapRegionRemSet::init_heap(max_regions());
2082
2083 // Now expand into the initial heap size.
2084 if (!expand(init_byte_size)) {
2085 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2086 return JNI_ENOMEM;
2087 }
2088
2089 // Perform any initialization actions delegated to the policy.
2090 g1_policy()->init();
2091
2092 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2093 SATB_Q_FL_lock,
2094 G1SATBProcessCompletedThreshold,
2095 Shared_SATB_Q_lock);
2096
2097 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2098 DirtyCardQ_CBL_mon,
2099 DirtyCardQ_FL_lock,
2100 concurrent_g1_refine()->yellow_zone(),
2101 concurrent_g1_refine()->red_zone(),
2102 Shared_DirtyCardQ_lock);
2103
2104 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2105 DirtyCardQ_CBL_mon,
2106 DirtyCardQ_FL_lock,
2107 -1, // never trigger processing
2108 -1, // no limit on length
2109 Shared_DirtyCardQ_lock,
2110 &JavaThread::dirty_card_queue_set());
2111
2112 // Initialize the card queue set used to hold cards containing
2113 // references into the collection set.
2114 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2115 DirtyCardQ_CBL_mon,
2116 DirtyCardQ_FL_lock,
2117 -1, // never trigger processing
2118 -1, // no limit on length
2119 Shared_DirtyCardQ_lock,
2120 &JavaThread::dirty_card_queue_set());
2121
2122 // In case we're keeping closure specialization stats, initialize those
2123 // counts and that mechanism.
2124 SpecializationStats::clear();
2125
2126 // Here we allocate the dummy HeapRegion that is required by the
2127 // G1AllocRegion class.
2128 HeapRegion* dummy_region = _hrm.get_dummy_region();
2129
2130 // We'll re-use the same region whether the alloc region will
2131 // require BOT updates or not and, if it doesn't, then a non-young
2132 // region will complain that it cannot support allocations without
2133 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2134 dummy_region->set_eden();
2135 // Make sure it's full.
2136 dummy_region->set_top(dummy_region->end());
2137 G1AllocRegion::setup(this, dummy_region);
2138
2139 _allocator->init_mutator_alloc_region();
2140
2141 // Do create of the monitoring and management support so that
2142 // values in the heap have been properly initialized.
2143 _g1mm = new G1MonitoringSupport(this);
2144
2145 G1StringDedup::initialize();
2146
2147 return JNI_OK;
2148 }
2149
2150 void G1CollectedHeap::stop() {
2151 // Stop all concurrent threads. We do this to make sure these threads
2152 // do not continue to execute and access resources (e.g. gclog_or_tty)
2153 // that are destroyed during shutdown.
2154 _cg1r->stop();
2155 _cmThread->stop();
2156 if (G1StringDedup::is_enabled()) {
2157 G1StringDedup::stop();
2158 }
2159 }
2160
2161 void G1CollectedHeap::clear_humongous_is_live_table() {
2162 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2163 _humongous_is_live.clear();
2164 }
2165
2166 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2167 return HeapRegion::max_region_size();
2168 }
2169
2170 void G1CollectedHeap::ref_processing_init() {
2171 // Reference processing in G1 currently works as follows:
2172 //
2173 // * There are two reference processor instances. One is
2174 // used to record and process discovered references
2175 // during concurrent marking; the other is used to
2176 // record and process references during STW pauses
2177 // (both full and incremental).
2178 // * Both ref processors need to 'span' the entire heap as
2179 // the regions in the collection set may be dotted around.
2180 //
2181 // * For the concurrent marking ref processor:
2182 // * Reference discovery is enabled at initial marking.
2183 // * Reference discovery is disabled and the discovered
2184 // references processed etc during remarking.
2185 // * Reference discovery is MT (see below).
2186 // * Reference discovery requires a barrier (see below).
2187 // * Reference processing may or may not be MT
2188 // (depending on the value of ParallelRefProcEnabled
2189 // and ParallelGCThreads).
2190 // * A full GC disables reference discovery by the CM
2191 // ref processor and abandons any entries on it's
2192 // discovered lists.
2193 //
2194 // * For the STW processor:
2195 // * Non MT discovery is enabled at the start of a full GC.
2196 // * Processing and enqueueing during a full GC is non-MT.
2197 // * During a full GC, references are processed after marking.
2198 //
2199 // * Discovery (may or may not be MT) is enabled at the start
2200 // of an incremental evacuation pause.
2201 // * References are processed near the end of a STW evacuation pause.
2202 // * For both types of GC:
2203 // * Discovery is atomic - i.e. not concurrent.
2204 // * Reference discovery will not need a barrier.
2205
2206 SharedHeap::ref_processing_init();
2207 MemRegion mr = reserved_region();
2208
2209 // Concurrent Mark ref processor
2210 _ref_processor_cm =
2211 new ReferenceProcessor(mr, // span
2212 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2213 // mt processing
2214 (int) ParallelGCThreads,
2215 // degree of mt processing
2216 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2217 // mt discovery
2218 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2219 // degree of mt discovery
2220 false,
2221 // Reference discovery is not atomic
2222 &_is_alive_closure_cm);
2223 // is alive closure
2224 // (for efficiency/performance)
2225
2226 // STW ref processor
2227 _ref_processor_stw =
2228 new ReferenceProcessor(mr, // span
2229 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2230 // mt processing
2231 MAX2((int)ParallelGCThreads, 1),
2232 // degree of mt processing
2233 (ParallelGCThreads > 1),
2234 // mt discovery
2235 MAX2((int)ParallelGCThreads, 1),
2236 // degree of mt discovery
2237 true,
2238 // Reference discovery is atomic
2239 &_is_alive_closure_stw);
2240 // is alive closure
2241 // (for efficiency/performance)
2242 }
2243
2244 size_t G1CollectedHeap::capacity() const {
2245 return _hrm.length() * HeapRegion::GrainBytes;
2246 }
2247
2248 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2249 assert(!hr->continuesHumongous(), "pre-condition");
2250 hr->reset_gc_time_stamp();
2251 if (hr->startsHumongous()) {
2252 uint first_index = hr->hrm_index() + 1;
2253 uint last_index = hr->last_hc_index();
2254 for (uint i = first_index; i < last_index; i += 1) {
2255 HeapRegion* chr = region_at(i);
2256 assert(chr->continuesHumongous(), "sanity");
2257 chr->reset_gc_time_stamp();
2258 }
2259 }
2260 }
2261
2262 #ifndef PRODUCT
2263 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2264 private:
2265 unsigned _gc_time_stamp;
2266 bool _failures;
2267
2268 public:
2269 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2270 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2271
2272 virtual bool doHeapRegion(HeapRegion* hr) {
2273 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2274 if (_gc_time_stamp != region_gc_time_stamp) {
2275 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2276 "expected %d", HR_FORMAT_PARAMS(hr),
2277 region_gc_time_stamp, _gc_time_stamp);
2278 _failures = true;
2279 }
2280 return false;
2281 }
2282
2283 bool failures() { return _failures; }
2284 };
2285
2286 void G1CollectedHeap::check_gc_time_stamps() {
2287 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2288 heap_region_iterate(&cl);
2289 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2290 }
2291 #endif // PRODUCT
2292
2293 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2294 DirtyCardQueue* into_cset_dcq,
2295 bool concurrent,
2296 uint worker_i) {
2297 // Clean cards in the hot card cache
2298 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2299 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2300
2301 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2302 int n_completed_buffers = 0;
2303 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2304 n_completed_buffers++;
2305 }
2306 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2307 dcqs.clear_n_completed_buffers();
2308 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2309 }
2310
2311
2312 // Computes the sum of the storage used by the various regions.
2313 size_t G1CollectedHeap::used() const {
2314 return _allocator->used();
2315 }
2316
2317 size_t G1CollectedHeap::used_unlocked() const {
2318 return _allocator->used_unlocked();
2319 }
2320
2321 class SumUsedClosure: public HeapRegionClosure {
2322 size_t _used;
2323 public:
2324 SumUsedClosure() : _used(0) {}
2325 bool doHeapRegion(HeapRegion* r) {
2326 if (!r->continuesHumongous()) {
2327 _used += r->used();
2328 }
2329 return false;
2330 }
2331 size_t result() { return _used; }
2332 };
2333
2334 size_t G1CollectedHeap::recalculate_used() const {
2335 double recalculate_used_start = os::elapsedTime();
2336
2337 SumUsedClosure blk;
2338 heap_region_iterate(&blk);
2339
2340 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2341 return blk.result();
2342 }
2343
2344 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2345 switch (cause) {
2346 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2347 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2348 case GCCause::_g1_humongous_allocation: return true;
2349 case GCCause::_update_allocation_context_stats_inc: return true;
2350 default: return false;
2351 }
2352 }
2353
2354 #ifndef PRODUCT
2355 void G1CollectedHeap::allocate_dummy_regions() {
2356 // Let's fill up most of the region
2357 size_t word_size = HeapRegion::GrainWords - 1024;
2358 // And as a result the region we'll allocate will be humongous.
2359 guarantee(isHumongous(word_size), "sanity");
2360
2361 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2362 // Let's use the existing mechanism for the allocation
2363 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2364 AllocationContext::system());
2365 if (dummy_obj != NULL) {
2366 MemRegion mr(dummy_obj, word_size);
2367 CollectedHeap::fill_with_object(mr);
2368 } else {
2369 // If we can't allocate once, we probably cannot allocate
2370 // again. Let's get out of the loop.
2371 break;
2372 }
2373 }
2374 }
2375 #endif // !PRODUCT
2376
2377 void G1CollectedHeap::increment_old_marking_cycles_started() {
2378 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2379 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2380 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2381 _old_marking_cycles_started, _old_marking_cycles_completed));
2382
2383 _old_marking_cycles_started++;
2384 }
2385
2386 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2387 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2388
2389 // We assume that if concurrent == true, then the caller is a
2390 // concurrent thread that was joined the Suspendible Thread
2391 // Set. If there's ever a cheap way to check this, we should add an
2392 // assert here.
2393
2394 // Given that this method is called at the end of a Full GC or of a
2395 // concurrent cycle, and those can be nested (i.e., a Full GC can
2396 // interrupt a concurrent cycle), the number of full collections
2397 // completed should be either one (in the case where there was no
2398 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2399 // behind the number of full collections started.
2400
2401 // This is the case for the inner caller, i.e. a Full GC.
2402 assert(concurrent ||
2403 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2404 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2405 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2406 "is inconsistent with _old_marking_cycles_completed = %u",
2407 _old_marking_cycles_started, _old_marking_cycles_completed));
2408
2409 // This is the case for the outer caller, i.e. the concurrent cycle.
2410 assert(!concurrent ||
2411 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2412 err_msg("for outer caller (concurrent cycle): "
2413 "_old_marking_cycles_started = %u "
2414 "is inconsistent with _old_marking_cycles_completed = %u",
2415 _old_marking_cycles_started, _old_marking_cycles_completed));
2416
2417 _old_marking_cycles_completed += 1;
2418
2419 // We need to clear the "in_progress" flag in the CM thread before
2420 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2421 // is set) so that if a waiter requests another System.gc() it doesn't
2422 // incorrectly see that a marking cycle is still in progress.
2423 if (concurrent) {
2424 _cmThread->clear_in_progress();
2425 }
2426
2427 // This notify_all() will ensure that a thread that called
2428 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2429 // and it's waiting for a full GC to finish will be woken up. It is
2430 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2431 FullGCCount_lock->notify_all();
2432 }
2433
2434 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2435 _concurrent_cycle_started = true;
2436 _gc_timer_cm->register_gc_start(start_time);
2437
2438 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2439 trace_heap_before_gc(_gc_tracer_cm);
2440 }
2441
2442 void G1CollectedHeap::register_concurrent_cycle_end() {
2443 if (_concurrent_cycle_started) {
2444 if (_cm->has_aborted()) {
2445 _gc_tracer_cm->report_concurrent_mode_failure();
2446 }
2447
2448 _gc_timer_cm->register_gc_end();
2449 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2450
2451 _concurrent_cycle_started = false;
2452 }
2453 }
2454
2455 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2456 if (_concurrent_cycle_started) {
2457 trace_heap_after_gc(_gc_tracer_cm);
2458 }
2459 }
2460
2461 G1YCType G1CollectedHeap::yc_type() {
2462 bool is_young = g1_policy()->gcs_are_young();
2463 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2464 bool is_during_mark = mark_in_progress();
2465
2466 if (is_initial_mark) {
2467 return InitialMark;
2468 } else if (is_during_mark) {
2469 return DuringMark;
2470 } else if (is_young) {
2471 return Normal;
2472 } else {
2473 return Mixed;
2474 }
2475 }
2476
2477 void G1CollectedHeap::collect(GCCause::Cause cause) {
2478 assert_heap_not_locked();
2479
2480 unsigned int gc_count_before;
2481 unsigned int old_marking_count_before;
2482 unsigned int full_gc_count_before;
2483 bool retry_gc;
2484
2485 do {
2486 retry_gc = false;
2487
2488 {
2489 MutexLocker ml(Heap_lock);
2490
2491 // Read the GC count while holding the Heap_lock
2492 gc_count_before = total_collections();
2493 full_gc_count_before = total_full_collections();
2494 old_marking_count_before = _old_marking_cycles_started;
2495 }
2496
2497 if (should_do_concurrent_full_gc(cause)) {
2498 // Schedule an initial-mark evacuation pause that will start a
2499 // concurrent cycle. We're setting word_size to 0 which means that
2500 // we are not requesting a post-GC allocation.
2501 VM_G1IncCollectionPause op(gc_count_before,
2502 0, /* word_size */
2503 true, /* should_initiate_conc_mark */
2504 g1_policy()->max_pause_time_ms(),
2505 cause);
2506 op.set_allocation_context(AllocationContext::current());
2507
2508 VMThread::execute(&op);
2509 if (!op.pause_succeeded()) {
2510 if (old_marking_count_before == _old_marking_cycles_started) {
2511 retry_gc = op.should_retry_gc();
2512 } else {
2513 // A Full GC happened while we were trying to schedule the
2514 // initial-mark GC. No point in starting a new cycle given
2515 // that the whole heap was collected anyway.
2516 }
2517
2518 if (retry_gc) {
2519 if (GC_locker::is_active_and_needs_gc()) {
2520 GC_locker::stall_until_clear();
2521 }
2522 }
2523 }
2524 } else {
2525 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2526 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2527
2528 // Schedule a standard evacuation pause. We're setting word_size
2529 // to 0 which means that we are not requesting a post-GC allocation.
2530 VM_G1IncCollectionPause op(gc_count_before,
2531 0, /* word_size */
2532 false, /* should_initiate_conc_mark */
2533 g1_policy()->max_pause_time_ms(),
2534 cause);
2535 VMThread::execute(&op);
2536 } else {
2537 // Schedule a Full GC.
2538 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2539 VMThread::execute(&op);
2540 }
2541 }
2542 } while (retry_gc);
2543 }
2544
2545 bool G1CollectedHeap::is_in(const void* p) const {
2546 if (_hrm.reserved().contains(p)) {
2547 // Given that we know that p is in the reserved space,
2548 // heap_region_containing_raw() should successfully
2549 // return the containing region.
2550 HeapRegion* hr = heap_region_containing_raw(p);
2551 return hr->is_in(p);
2552 } else {
2553 return false;
2554 }
2555 }
2556
2557 #ifdef ASSERT
2558 bool G1CollectedHeap::is_in_exact(const void* p) const {
2559 bool contains = reserved_region().contains(p);
2560 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2561 if (contains && available) {
2562 return true;
2563 } else {
2564 return false;
2565 }
2566 }
2567 #endif
2568
2569 // Iteration functions.
2570
2571 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2572
2573 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2574 ExtendedOopClosure* _cl;
2575 public:
2576 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2577 bool doHeapRegion(HeapRegion* r) {
2578 if (!r->continuesHumongous()) {
2579 r->oop_iterate(_cl);
2580 }
2581 return false;
2582 }
2583 };
2584
2585 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2586 IterateOopClosureRegionClosure blk(cl);
2587 heap_region_iterate(&blk);
2588 }
2589
2590 // Iterates an ObjectClosure over all objects within a HeapRegion.
2591
2592 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2593 ObjectClosure* _cl;
2594 public:
2595 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2596 bool doHeapRegion(HeapRegion* r) {
2597 if (! r->continuesHumongous()) {
2598 r->object_iterate(_cl);
2599 }
2600 return false;
2601 }
2602 };
2603
2604 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2605 IterateObjectClosureRegionClosure blk(cl);
2606 heap_region_iterate(&blk);
2607 }
2608
2609 // Calls a SpaceClosure on a HeapRegion.
2610
2611 class SpaceClosureRegionClosure: public HeapRegionClosure {
2612 SpaceClosure* _cl;
2613 public:
2614 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2615 bool doHeapRegion(HeapRegion* r) {
2616 _cl->do_space(r);
2617 return false;
2618 }
2619 };
2620
2621 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2622 SpaceClosureRegionClosure blk(cl);
2623 heap_region_iterate(&blk);
2624 }
2625
2626 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2627 _hrm.iterate(cl);
2628 }
2629
2630 void
2631 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2632 uint worker_id,
2633 uint num_workers,
2634 jint claim_value) const {
2635 _hrm.par_iterate(cl, worker_id, num_workers, claim_value);
2636 }
2637
2638 class ResetClaimValuesClosure: public HeapRegionClosure {
2639 public:
2640 bool doHeapRegion(HeapRegion* r) {
2641 r->set_claim_value(HeapRegion::InitialClaimValue);
2642 return false;
2643 }
2644 };
2645
2646 void G1CollectedHeap::reset_heap_region_claim_values() {
2647 ResetClaimValuesClosure blk;
2648 heap_region_iterate(&blk);
2649 }
2650
2651 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2652 ResetClaimValuesClosure blk;
2653 collection_set_iterate(&blk);
2654 }
2655
2656 #ifdef ASSERT
2657 // This checks whether all regions in the heap have the correct claim
2658 // value. I also piggy-backed on this a check to ensure that the
2659 // humongous_start_region() information on "continues humongous"
2660 // regions is correct.
2661
2662 class CheckClaimValuesClosure : public HeapRegionClosure {
2663 private:
2664 jint _claim_value;
2665 uint _failures;
2666 HeapRegion* _sh_region;
2667
2668 public:
2669 CheckClaimValuesClosure(jint claim_value) :
2670 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2671 bool doHeapRegion(HeapRegion* r) {
2672 if (r->claim_value() != _claim_value) {
2673 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2674 "claim value = %d, should be %d",
2675 HR_FORMAT_PARAMS(r),
2676 r->claim_value(), _claim_value);
2677 ++_failures;
2678 }
2679 if (!r->isHumongous()) {
2680 _sh_region = NULL;
2681 } else if (r->startsHumongous()) {
2682 _sh_region = r;
2683 } else if (r->continuesHumongous()) {
2684 if (r->humongous_start_region() != _sh_region) {
2685 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2686 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2687 HR_FORMAT_PARAMS(r),
2688 r->humongous_start_region(),
2689 _sh_region);
2690 ++_failures;
2691 }
2692 }
2693 return false;
2694 }
2695 uint failures() { return _failures; }
2696 };
2697
2698 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2699 CheckClaimValuesClosure cl(claim_value);
2700 heap_region_iterate(&cl);
2701 return cl.failures() == 0;
2702 }
2703
2704 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2705 private:
2706 jint _claim_value;
2707 uint _failures;
2708
2709 public:
2710 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2711 _claim_value(claim_value), _failures(0) { }
2712
2713 uint failures() { return _failures; }
2714
2715 bool doHeapRegion(HeapRegion* hr) {
2716 assert(hr->in_collection_set(), "how?");
2717 assert(!hr->isHumongous(), "H-region in CSet");
2718 if (hr->claim_value() != _claim_value) {
2719 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2720 "claim value = %d, should be %d",
2721 HR_FORMAT_PARAMS(hr),
2722 hr->claim_value(), _claim_value);
2723 _failures += 1;
2724 }
2725 return false;
2726 }
2727 };
2728
2729 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2730 CheckClaimValuesInCSetHRClosure cl(claim_value);
2731 collection_set_iterate(&cl);
2732 return cl.failures() == 0;
2733 }
2734 #endif // ASSERT
2735
2736 // Clear the cached CSet starting regions and (more importantly)
2737 // the time stamps. Called when we reset the GC time stamp.
2738 void G1CollectedHeap::clear_cset_start_regions() {
2739 assert(_worker_cset_start_region != NULL, "sanity");
2740 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2741
2742 int n_queues = MAX2((int)ParallelGCThreads, 1);
2743 for (int i = 0; i < n_queues; i++) {
2744 _worker_cset_start_region[i] = NULL;
2745 _worker_cset_start_region_time_stamp[i] = 0;
2746 }
2747 }
2748
2749 // Given the id of a worker, obtain or calculate a suitable
2750 // starting region for iterating over the current collection set.
2751 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2752 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2753
2754 HeapRegion* result = NULL;
2755 unsigned gc_time_stamp = get_gc_time_stamp();
2756
2757 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2758 // Cached starting region for current worker was set
2759 // during the current pause - so it's valid.
2760 // Note: the cached starting heap region may be NULL
2761 // (when the collection set is empty).
2762 result = _worker_cset_start_region[worker_i];
2763 assert(result == NULL || result->in_collection_set(), "sanity");
2764 return result;
2765 }
2766
2767 // The cached entry was not valid so let's calculate
2768 // a suitable starting heap region for this worker.
2769
2770 // We want the parallel threads to start their collection
2771 // set iteration at different collection set regions to
2772 // avoid contention.
2773 // If we have:
2774 // n collection set regions
2775 // p threads
2776 // Then thread t will start at region floor ((t * n) / p)
2777
2778 result = g1_policy()->collection_set();
2779 if (G1CollectedHeap::use_parallel_gc_threads()) {
2780 uint cs_size = g1_policy()->cset_region_length();
2781 uint active_workers = workers()->active_workers();
2782 assert(UseDynamicNumberOfGCThreads ||
2783 active_workers == workers()->total_workers(),
2784 "Unless dynamic should use total workers");
2785
2786 uint end_ind = (cs_size * worker_i) / active_workers;
2787 uint start_ind = 0;
2788
2789 if (worker_i > 0 &&
2790 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2791 // Previous workers starting region is valid
2792 // so let's iterate from there
2793 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2794 result = _worker_cset_start_region[worker_i - 1];
2795 }
2796
2797 for (uint i = start_ind; i < end_ind; i++) {
2798 result = result->next_in_collection_set();
2799 }
2800 }
2801
2802 // Note: the calculated starting heap region may be NULL
2803 // (when the collection set is empty).
2804 assert(result == NULL || result->in_collection_set(), "sanity");
2805 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2806 "should be updated only once per pause");
2807 _worker_cset_start_region[worker_i] = result;
2808 OrderAccess::storestore();
2809 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2810 return result;
2811 }
2812
2813 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2814 HeapRegion* r = g1_policy()->collection_set();
2815 while (r != NULL) {
2816 HeapRegion* next = r->next_in_collection_set();
2817 if (cl->doHeapRegion(r)) {
2818 cl->incomplete();
2819 return;
2820 }
2821 r = next;
2822 }
2823 }
2824
2825 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2826 HeapRegionClosure *cl) {
2827 if (r == NULL) {
2828 // The CSet is empty so there's nothing to do.
2829 return;
2830 }
2831
2832 assert(r->in_collection_set(),
2833 "Start region must be a member of the collection set.");
2834 HeapRegion* cur = r;
2835 while (cur != NULL) {
2836 HeapRegion* next = cur->next_in_collection_set();
2837 if (cl->doHeapRegion(cur) && false) {
2838 cl->incomplete();
2839 return;
2840 }
2841 cur = next;
2842 }
2843 cur = g1_policy()->collection_set();
2844 while (cur != r) {
2845 HeapRegion* next = cur->next_in_collection_set();
2846 if (cl->doHeapRegion(cur) && false) {
2847 cl->incomplete();
2848 return;
2849 }
2850 cur = next;
2851 }
2852 }
2853
2854 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2855 HeapRegion* result = _hrm.next_region_in_heap(from);
2856 while (result != NULL && result->isHumongous()) {
2857 result = _hrm.next_region_in_heap(result);
2858 }
2859 return result;
2860 }
2861
2862 Space* G1CollectedHeap::space_containing(const void* addr) const {
2863 return heap_region_containing(addr);
2864 }
2865
2866 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2867 Space* sp = space_containing(addr);
2868 return sp->block_start(addr);
2869 }
2870
2871 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2872 Space* sp = space_containing(addr);
2873 return sp->block_size(addr);
2874 }
2875
2876 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2877 Space* sp = space_containing(addr);
2878 return sp->block_is_obj(addr);
2879 }
2880
2881 bool G1CollectedHeap::supports_tlab_allocation() const {
2882 return true;
2883 }
2884
2885 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2886 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2887 }
2888
2889 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2890 return young_list()->eden_used_bytes();
2891 }
2892
2893 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2894 // must be smaller than the humongous object limit.
2895 size_t G1CollectedHeap::max_tlab_size() const {
2896 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2897 }
2898
2899 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2900 // Return the remaining space in the cur alloc region, but not less than
2901 // the min TLAB size.
2902
2903 // Also, this value can be at most the humongous object threshold,
2904 // since we can't allow tlabs to grow big enough to accommodate
2905 // humongous objects.
2906
2907 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2908 size_t max_tlab = max_tlab_size() * wordSize;
2909 if (hr == NULL) {
2910 return max_tlab;
2911 } else {
2912 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2913 }
2914 }
2915
2916 size_t G1CollectedHeap::max_capacity() const {
2917 return _hrm.reserved().byte_size();
2918 }
2919
2920 jlong G1CollectedHeap::millis_since_last_gc() {
2921 // assert(false, "NYI");
2922 return 0;
2923 }
2924
2925 void G1CollectedHeap::prepare_for_verify() {
2926 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2927 ensure_parsability(false);
2928 }
2929 g1_rem_set()->prepare_for_verify();
2930 }
2931
2932 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2933 VerifyOption vo) {
2934 switch (vo) {
2935 case VerifyOption_G1UsePrevMarking:
2936 return hr->obj_allocated_since_prev_marking(obj);
2937 case VerifyOption_G1UseNextMarking:
2938 return hr->obj_allocated_since_next_marking(obj);
2939 case VerifyOption_G1UseMarkWord:
2940 return false;
2941 default:
2942 ShouldNotReachHere();
2943 }
2944 return false; // keep some compilers happy
2945 }
2946
2947 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2948 switch (vo) {
2949 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2950 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2951 case VerifyOption_G1UseMarkWord: return NULL;
2952 default: ShouldNotReachHere();
2953 }
2954 return NULL; // keep some compilers happy
2955 }
2956
2957 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2958 switch (vo) {
2959 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2960 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2961 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2962 default: ShouldNotReachHere();
2963 }
2964 return false; // keep some compilers happy
2965 }
2966
2967 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2968 switch (vo) {
2969 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2970 case VerifyOption_G1UseNextMarking: return "NTAMS";
2971 case VerifyOption_G1UseMarkWord: return "NONE";
2972 default: ShouldNotReachHere();
2973 }
2974 return NULL; // keep some compilers happy
2975 }
2976
2977 class VerifyRootsClosure: public OopClosure {
2978 private:
2979 G1CollectedHeap* _g1h;
2980 VerifyOption _vo;
2981 bool _failures;
2982 public:
2983 // _vo == UsePrevMarking -> use "prev" marking information,
2984 // _vo == UseNextMarking -> use "next" marking information,
2985 // _vo == UseMarkWord -> use mark word from object header.
2986 VerifyRootsClosure(VerifyOption vo) :
2987 _g1h(G1CollectedHeap::heap()),
2988 _vo(vo),
2989 _failures(false) { }
2990
2991 bool failures() { return _failures; }
2992
2993 template <class T> void do_oop_nv(T* p) {
2994 T heap_oop = oopDesc::load_heap_oop(p);
2995 if (!oopDesc::is_null(heap_oop)) {
2996 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2997 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2998 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2999 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3000 if (_vo == VerifyOption_G1UseMarkWord) {
3001 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3002 }
3003 obj->print_on(gclog_or_tty);
3004 _failures = true;
3005 }
3006 }
3007 }
3008
3009 void do_oop(oop* p) { do_oop_nv(p); }
3010 void do_oop(narrowOop* p) { do_oop_nv(p); }
3011 };
3012
3013 class G1VerifyCodeRootOopClosure: public OopClosure {
3014 G1CollectedHeap* _g1h;
3015 OopClosure* _root_cl;
3016 nmethod* _nm;
3017 VerifyOption _vo;
3018 bool _failures;
3019
3020 template <class T> void do_oop_work(T* p) {
3021 // First verify that this root is live
3022 _root_cl->do_oop(p);
3023
3024 if (!G1VerifyHeapRegionCodeRoots) {
3025 // We're not verifying the code roots attached to heap region.
3026 return;
3027 }
3028
3029 // Don't check the code roots during marking verification in a full GC
3030 if (_vo == VerifyOption_G1UseMarkWord) {
3031 return;
3032 }
3033
3034 // Now verify that the current nmethod (which contains p) is
3035 // in the code root list of the heap region containing the
3036 // object referenced by p.
3037
3038 T heap_oop = oopDesc::load_heap_oop(p);
3039 if (!oopDesc::is_null(heap_oop)) {
3040 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3041
3042 // Now fetch the region containing the object
3043 HeapRegion* hr = _g1h->heap_region_containing(obj);
3044 HeapRegionRemSet* hrrs = hr->rem_set();
3045 // Verify that the strong code root list for this region
3046 // contains the nmethod
3047 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3048 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3049 "from nmethod "PTR_FORMAT" not in strong "
3050 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3051 p, _nm, hr->bottom(), hr->end());
3052 _failures = true;
3053 }
3054 }
3055 }
3056
3057 public:
3058 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3059 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3060
3061 void do_oop(oop* p) { do_oop_work(p); }
3062 void do_oop(narrowOop* p) { do_oop_work(p); }
3063
3064 void set_nmethod(nmethod* nm) { _nm = nm; }
3065 bool failures() { return _failures; }
3066 };
3067
3068 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3069 G1VerifyCodeRootOopClosure* _oop_cl;
3070
3071 public:
3072 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3073 _oop_cl(oop_cl) {}
3074
3075 void do_code_blob(CodeBlob* cb) {
3076 nmethod* nm = cb->as_nmethod_or_null();
3077 if (nm != NULL) {
3078 _oop_cl->set_nmethod(nm);
3079 nm->oops_do(_oop_cl);
3080 }
3081 }
3082 };
3083
3084 class YoungRefCounterClosure : public OopClosure {
3085 G1CollectedHeap* _g1h;
3086 int _count;
3087 public:
3088 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3089 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3090 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3091
3092 int count() { return _count; }
3093 void reset_count() { _count = 0; };
3094 };
3095
3096 class VerifyKlassClosure: public KlassClosure {
3097 YoungRefCounterClosure _young_ref_counter_closure;
3098 OopClosure *_oop_closure;
3099 public:
3100 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3101 void do_klass(Klass* k) {
3102 k->oops_do(_oop_closure);
3103
3104 _young_ref_counter_closure.reset_count();
3105 k->oops_do(&_young_ref_counter_closure);
3106 if (_young_ref_counter_closure.count() > 0) {
3107 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3108 }
3109 }
3110 };
3111
3112 class VerifyLivenessOopClosure: public OopClosure {
3113 G1CollectedHeap* _g1h;
3114 VerifyOption _vo;
3115 public:
3116 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3117 _g1h(g1h), _vo(vo)
3118 { }
3119 void do_oop(narrowOop *p) { do_oop_work(p); }
3120 void do_oop( oop *p) { do_oop_work(p); }
3121
3122 template <class T> void do_oop_work(T *p) {
3123 oop obj = oopDesc::load_decode_heap_oop(p);
3124 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3125 "Dead object referenced by a not dead object");
3126 }
3127 };
3128
3129 class VerifyObjsInRegionClosure: public ObjectClosure {
3130 private:
3131 G1CollectedHeap* _g1h;
3132 size_t _live_bytes;
3133 HeapRegion *_hr;
3134 VerifyOption _vo;
3135 public:
3136 // _vo == UsePrevMarking -> use "prev" marking information,
3137 // _vo == UseNextMarking -> use "next" marking information,
3138 // _vo == UseMarkWord -> use mark word from object header.
3139 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3140 : _live_bytes(0), _hr(hr), _vo(vo) {
3141 _g1h = G1CollectedHeap::heap();
3142 }
3143 void do_object(oop o) {
3144 VerifyLivenessOopClosure isLive(_g1h, _vo);
3145 assert(o != NULL, "Huh?");
3146 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3147 // If the object is alive according to the mark word,
3148 // then verify that the marking information agrees.
3149 // Note we can't verify the contra-positive of the
3150 // above: if the object is dead (according to the mark
3151 // word), it may not be marked, or may have been marked
3152 // but has since became dead, or may have been allocated
3153 // since the last marking.
3154 if (_vo == VerifyOption_G1UseMarkWord) {
3155 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3156 }
3157
3158 o->oop_iterate_no_header(&isLive);
3159 if (!_hr->obj_allocated_since_prev_marking(o)) {
3160 size_t obj_size = o->size(); // Make sure we don't overflow
3161 _live_bytes += (obj_size * HeapWordSize);
3162 }
3163 }
3164 }
3165 size_t live_bytes() { return _live_bytes; }
3166 };
3167
3168 class PrintObjsInRegionClosure : public ObjectClosure {
3169 HeapRegion *_hr;
3170 G1CollectedHeap *_g1;
3171 public:
3172 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3173 _g1 = G1CollectedHeap::heap();
3174 };
3175
3176 void do_object(oop o) {
3177 if (o != NULL) {
3178 HeapWord *start = (HeapWord *) o;
3179 size_t word_sz = o->size();
3180 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3181 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3182 (void*) o, word_sz,
3183 _g1->isMarkedPrev(o),
3184 _g1->isMarkedNext(o),
3185 _hr->obj_allocated_since_prev_marking(o));
3186 HeapWord *end = start + word_sz;
3187 HeapWord *cur;
3188 int *val;
3189 for (cur = start; cur < end; cur++) {
3190 val = (int *) cur;
3191 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3192 }
3193 }
3194 }
3195 };
3196
3197 class VerifyRegionClosure: public HeapRegionClosure {
3198 private:
3199 bool _par;
3200 VerifyOption _vo;
3201 bool _failures;
3202 public:
3203 // _vo == UsePrevMarking -> use "prev" marking information,
3204 // _vo == UseNextMarking -> use "next" marking information,
3205 // _vo == UseMarkWord -> use mark word from object header.
3206 VerifyRegionClosure(bool par, VerifyOption vo)
3207 : _par(par),
3208 _vo(vo),
3209 _failures(false) {}
3210
3211 bool failures() {
3212 return _failures;
3213 }
3214
3215 bool doHeapRegion(HeapRegion* r) {
3216 if (!r->continuesHumongous()) {
3217 bool failures = false;
3218 r->verify(_vo, &failures);
3219 if (failures) {
3220 _failures = true;
3221 } else {
3222 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3223 r->object_iterate(¬_dead_yet_cl);
3224 if (_vo != VerifyOption_G1UseNextMarking) {
3225 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3226 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3227 "max_live_bytes "SIZE_FORMAT" "
3228 "< calculated "SIZE_FORMAT,
3229 r->bottom(), r->end(),
3230 r->max_live_bytes(),
3231 not_dead_yet_cl.live_bytes());
3232 _failures = true;
3233 }
3234 } else {
3235 // When vo == UseNextMarking we cannot currently do a sanity
3236 // check on the live bytes as the calculation has not been
3237 // finalized yet.
3238 }
3239 }
3240 }
3241 return false; // stop the region iteration if we hit a failure
3242 }
3243 };
3244
3245 // This is the task used for parallel verification of the heap regions
3246
3247 class G1ParVerifyTask: public AbstractGangTask {
3248 private:
3249 G1CollectedHeap* _g1h;
3250 VerifyOption _vo;
3251 bool _failures;
3252
3253 public:
3254 // _vo == UsePrevMarking -> use "prev" marking information,
3255 // _vo == UseNextMarking -> use "next" marking information,
3256 // _vo == UseMarkWord -> use mark word from object header.
3257 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3258 AbstractGangTask("Parallel verify task"),
3259 _g1h(g1h),
3260 _vo(vo),
3261 _failures(false) { }
3262
3263 bool failures() {
3264 return _failures;
3265 }
3266
3267 void work(uint worker_id) {
3268 HandleMark hm;
3269 VerifyRegionClosure blk(true, _vo);
3270 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3271 _g1h->workers()->active_workers(),
3272 HeapRegion::ParVerifyClaimValue);
3273 if (blk.failures()) {
3274 _failures = true;
3275 }
3276 }
3277 };
3278
3279 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3280 if (SafepointSynchronize::is_at_safepoint()) {
3281 assert(Thread::current()->is_VM_thread(),
3282 "Expected to be executed serially by the VM thread at this point");
3283
3284 if (!silent) { gclog_or_tty->print("Roots "); }
3285 VerifyRootsClosure rootsCl(vo);
3286 VerifyKlassClosure klassCl(this, &rootsCl);
3287 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3288
3289 // We apply the relevant closures to all the oops in the
3290 // system dictionary, class loader data graph, the string table
3291 // and the nmethods in the code cache.
3292 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3293 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3294
3295 process_all_roots(true, // activate StrongRootsScope
3296 SO_AllCodeCache, // roots scanning options
3297 &rootsCl,
3298 &cldCl,
3299 &blobsCl);
3300
3301 bool failures = rootsCl.failures() || codeRootsCl.failures();
3302
3303 if (vo != VerifyOption_G1UseMarkWord) {
3304 // If we're verifying during a full GC then the region sets
3305 // will have been torn down at the start of the GC. Therefore
3306 // verifying the region sets will fail. So we only verify
3307 // the region sets when not in a full GC.
3308 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3309 verify_region_sets();
3310 }
3311
3312 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3313 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3314 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3315 "sanity check");
3316
3317 G1ParVerifyTask task(this, vo);
3318 assert(UseDynamicNumberOfGCThreads ||
3319 workers()->active_workers() == workers()->total_workers(),
3320 "If not dynamic should be using all the workers");
3321 int n_workers = workers()->active_workers();
3322 set_par_threads(n_workers);
3323 workers()->run_task(&task);
3324 set_par_threads(0);
3325 if (task.failures()) {
3326 failures = true;
3327 }
3328
3329 // Checks that the expected amount of parallel work was done.
3330 // The implication is that n_workers is > 0.
3331 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3332 "sanity check");
3333
3334 reset_heap_region_claim_values();
3335
3336 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3337 "sanity check");
3338 } else {
3339 VerifyRegionClosure blk(false, vo);
3340 heap_region_iterate(&blk);
3341 if (blk.failures()) {
3342 failures = true;
3343 }
3344 }
3345 if (!silent) gclog_or_tty->print("RemSet ");
3346 rem_set()->verify();
3347
3348 if (G1StringDedup::is_enabled()) {
3349 if (!silent) gclog_or_tty->print("StrDedup ");
3350 G1StringDedup::verify();
3351 }
3352
3353 if (failures) {
3354 gclog_or_tty->print_cr("Heap:");
3355 // It helps to have the per-region information in the output to
3356 // help us track down what went wrong. This is why we call
3357 // print_extended_on() instead of print_on().
3358 print_extended_on(gclog_or_tty);
3359 gclog_or_tty->cr();
3360 #ifndef PRODUCT
3361 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3362 concurrent_mark()->print_reachable("at-verification-failure",
3363 vo, false /* all */);
3364 }
3365 #endif
3366 gclog_or_tty->flush();
3367 }
3368 guarantee(!failures, "there should not have been any failures");
3369 } else {
3370 if (!silent) {
3371 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3372 if (G1StringDedup::is_enabled()) {
3373 gclog_or_tty->print(", StrDedup");
3374 }
3375 gclog_or_tty->print(") ");
3376 }
3377 }
3378 }
3379
3380 void G1CollectedHeap::verify(bool silent) {
3381 verify(silent, VerifyOption_G1UsePrevMarking);
3382 }
3383
3384 double G1CollectedHeap::verify(bool guard, const char* msg) {
3385 double verify_time_ms = 0.0;
3386
3387 if (guard && total_collections() >= VerifyGCStartAt) {
3388 double verify_start = os::elapsedTime();
3389 HandleMark hm; // Discard invalid handles created during verification
3390 prepare_for_verify();
3391 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3392 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3393 }
3394
3395 return verify_time_ms;
3396 }
3397
3398 void G1CollectedHeap::verify_before_gc() {
3399 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3400 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3401 }
3402
3403 void G1CollectedHeap::verify_after_gc() {
3404 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3405 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3406 }
3407
3408 class PrintRegionClosure: public HeapRegionClosure {
3409 outputStream* _st;
3410 public:
3411 PrintRegionClosure(outputStream* st) : _st(st) {}
3412 bool doHeapRegion(HeapRegion* r) {
3413 r->print_on(_st);
3414 return false;
3415 }
3416 };
3417
3418 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3419 const HeapRegion* hr,
3420 const VerifyOption vo) const {
3421 switch (vo) {
3422 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3423 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3424 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3425 default: ShouldNotReachHere();
3426 }
3427 return false; // keep some compilers happy
3428 }
3429
3430 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3431 const VerifyOption vo) const {
3432 switch (vo) {
3433 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3434 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3435 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3436 default: ShouldNotReachHere();
3437 }
3438 return false; // keep some compilers happy
3439 }
3440
3441 void G1CollectedHeap::print_on(outputStream* st) const {
3442 st->print(" %-20s", "garbage-first heap");
3443 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3444 capacity()/K, used_unlocked()/K);
3445 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3446 _hrm.reserved().start(),
3447 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3448 _hrm.reserved().end());
3449 st->cr();
3450 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3451 uint young_regions = _young_list->length();
3452 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3453 (size_t) young_regions * HeapRegion::GrainBytes / K);
3454 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3455 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3456 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3457 st->cr();
3458 MetaspaceAux::print_on(st);
3459 }
3460
3461 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3462 print_on(st);
3463
3464 // Print the per-region information.
3465 st->cr();
3466 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3467 "HS=humongous(starts), HC=humongous(continues), "
3468 "CS=collection set, F=free, TS=gc time stamp, "
3469 "PTAMS=previous top-at-mark-start, "
3470 "NTAMS=next top-at-mark-start)");
3471 PrintRegionClosure blk(st);
3472 heap_region_iterate(&blk);
3473 }
3474
3475 void G1CollectedHeap::print_on_error(outputStream* st) const {
3476 this->CollectedHeap::print_on_error(st);
3477
3478 if (_cm != NULL) {
3479 st->cr();
3480 _cm->print_on_error(st);
3481 }
3482 }
3483
3484 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3485 if (G1CollectedHeap::use_parallel_gc_threads()) {
3486 workers()->print_worker_threads_on(st);
3487 }
3488 _cmThread->print_on(st);
3489 st->cr();
3490 _cm->print_worker_threads_on(st);
3491 _cg1r->print_worker_threads_on(st);
3492 if (G1StringDedup::is_enabled()) {
3493 G1StringDedup::print_worker_threads_on(st);
3494 }
3495 }
3496
3497 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3498 if (G1CollectedHeap::use_parallel_gc_threads()) {
3499 workers()->threads_do(tc);
3500 }
3501 tc->do_thread(_cmThread);
3502 _cg1r->threads_do(tc);
3503 if (G1StringDedup::is_enabled()) {
3504 G1StringDedup::threads_do(tc);
3505 }
3506 }
3507
3508 void G1CollectedHeap::print_tracing_info() const {
3509 // We'll overload this to mean "trace GC pause statistics."
3510 if (TraceGen0Time || TraceGen1Time) {
3511 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3512 // to that.
3513 g1_policy()->print_tracing_info();
3514 }
3515 if (G1SummarizeRSetStats) {
3516 g1_rem_set()->print_summary_info();
3517 }
3518 if (G1SummarizeConcMark) {
3519 concurrent_mark()->print_summary_info();
3520 }
3521 g1_policy()->print_yg_surv_rate_info();
3522 SpecializationStats::print();
3523 }
3524
3525 #ifndef PRODUCT
3526 // Helpful for debugging RSet issues.
3527
3528 class PrintRSetsClosure : public HeapRegionClosure {
3529 private:
3530 const char* _msg;
3531 size_t _occupied_sum;
3532
3533 public:
3534 bool doHeapRegion(HeapRegion* r) {
3535 HeapRegionRemSet* hrrs = r->rem_set();
3536 size_t occupied = hrrs->occupied();
3537 _occupied_sum += occupied;
3538
3539 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3540 HR_FORMAT_PARAMS(r));
3541 if (occupied == 0) {
3542 gclog_or_tty->print_cr(" RSet is empty");
3543 } else {
3544 hrrs->print();
3545 }
3546 gclog_or_tty->print_cr("----------");
3547 return false;
3548 }
3549
3550 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3551 gclog_or_tty->cr();
3552 gclog_or_tty->print_cr("========================================");
3553 gclog_or_tty->print_cr("%s", msg);
3554 gclog_or_tty->cr();
3555 }
3556
3557 ~PrintRSetsClosure() {
3558 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3559 gclog_or_tty->print_cr("========================================");
3560 gclog_or_tty->cr();
3561 }
3562 };
3563
3564 void G1CollectedHeap::print_cset_rsets() {
3565 PrintRSetsClosure cl("Printing CSet RSets");
3566 collection_set_iterate(&cl);
3567 }
3568
3569 void G1CollectedHeap::print_all_rsets() {
3570 PrintRSetsClosure cl("Printing All RSets");;
3571 heap_region_iterate(&cl);
3572 }
3573 #endif // PRODUCT
3574
3575 G1CollectedHeap* G1CollectedHeap::heap() {
3576 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3577 "not a garbage-first heap");
3578 return _g1h;
3579 }
3580
3581 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3582 // always_do_update_barrier = false;
3583 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3584 // Fill TLAB's and such
3585 accumulate_statistics_all_tlabs();
3586 ensure_parsability(true);
3587
3588 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3589 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3590 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3591 }
3592 }
3593
3594 void G1CollectedHeap::gc_epilogue(bool full) {
3595
3596 if (G1SummarizeRSetStats &&
3597 (G1SummarizeRSetStatsPeriod > 0) &&
3598 // we are at the end of the GC. Total collections has already been increased.
3599 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3600 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3601 }
3602
3603 // FIXME: what is this about?
3604 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3605 // is set.
3606 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3607 "derived pointer present"));
3608 // always_do_update_barrier = true;
3609
3610 resize_all_tlabs();
3611 allocation_context_stats().update(full);
3612
3613 // We have just completed a GC. Update the soft reference
3614 // policy with the new heap occupancy
3615 Universe::update_heap_info_at_gc();
3616 }
3617
3618 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3619 unsigned int gc_count_before,
3620 bool* succeeded,
3621 GCCause::Cause gc_cause) {
3622 assert_heap_not_locked_and_not_at_safepoint();
3623 g1_policy()->record_stop_world_start();
3624 VM_G1IncCollectionPause op(gc_count_before,
3625 word_size,
3626 false, /* should_initiate_conc_mark */
3627 g1_policy()->max_pause_time_ms(),
3628 gc_cause);
3629
3630 op.set_allocation_context(AllocationContext::current());
3631 VMThread::execute(&op);
3632
3633 HeapWord* result = op.result();
3634 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3635 assert(result == NULL || ret_succeeded,
3636 "the result should be NULL if the VM did not succeed");
3637 *succeeded = ret_succeeded;
3638
3639 assert_heap_not_locked();
3640 return result;
3641 }
3642
3643 void
3644 G1CollectedHeap::doConcurrentMark() {
3645 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3646 if (!_cmThread->in_progress()) {
3647 _cmThread->set_started();
3648 CGC_lock->notify();
3649 }
3650 }
3651
3652 size_t G1CollectedHeap::pending_card_num() {
3653 size_t extra_cards = 0;
3654 JavaThread *curr = Threads::first();
3655 while (curr != NULL) {
3656 DirtyCardQueue& dcq = curr->dirty_card_queue();
3657 extra_cards += dcq.size();
3658 curr = curr->next();
3659 }
3660 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3661 size_t buffer_size = dcqs.buffer_size();
3662 size_t buffer_num = dcqs.completed_buffers_num();
3663
3664 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3665 // in bytes - not the number of 'entries'. We need to convert
3666 // into a number of cards.
3667 return (buffer_size * buffer_num + extra_cards) / oopSize;
3668 }
3669
3670 size_t G1CollectedHeap::cards_scanned() {
3671 return g1_rem_set()->cardsScanned();
3672 }
3673
3674 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3675 HeapRegion* region = region_at(index);
3676 assert(region->startsHumongous(), "Must start a humongous object");
3677 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3678 }
3679
3680 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3681 private:
3682 size_t _total_humongous;
3683 size_t _candidate_humongous;
3684 public:
3685 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3686 }
3687
3688 virtual bool doHeapRegion(HeapRegion* r) {
3689 if (!r->startsHumongous()) {
3690 return false;
3691 }
3692 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3693
3694 uint region_idx = r->hrm_index();
3695 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3696 // Is_candidate already filters out humongous regions with some remembered set.
3697 // This will not lead to humongous object that we mistakenly keep alive because
3698 // during young collection the remembered sets will only be added to.
3699 if (is_candidate) {
3700 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3701 _candidate_humongous++;
3702 }
3703 _total_humongous++;
3704
3705 return false;
3706 }
3707
3708 size_t total_humongous() const { return _total_humongous; }
3709 size_t candidate_humongous() const { return _candidate_humongous; }
3710 };
3711
3712 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3713 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3714 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3715 return;
3716 }
3717
3718 RegisterHumongousWithInCSetFastTestClosure cl;
3719 heap_region_iterate(&cl);
3720 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3721 cl.candidate_humongous());
3722 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3723
3724 if (_has_humongous_reclaim_candidates) {
3725 clear_humongous_is_live_table();
3726 }
3727 }
3728
3729 void
3730 G1CollectedHeap::setup_surviving_young_words() {
3731 assert(_surviving_young_words == NULL, "pre-condition");
3732 uint array_length = g1_policy()->young_cset_region_length();
3733 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3734 if (_surviving_young_words == NULL) {
3735 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3736 "Not enough space for young surv words summary.");
3737 }
3738 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3739 #ifdef ASSERT
3740 for (uint i = 0; i < array_length; ++i) {
3741 assert( _surviving_young_words[i] == 0, "memset above" );
3742 }
3743 #endif // !ASSERT
3744 }
3745
3746 void
3747 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3748 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3749 uint array_length = g1_policy()->young_cset_region_length();
3750 for (uint i = 0; i < array_length; ++i) {
3751 _surviving_young_words[i] += surv_young_words[i];
3752 }
3753 }
3754
3755 void
3756 G1CollectedHeap::cleanup_surviving_young_words() {
3757 guarantee( _surviving_young_words != NULL, "pre-condition" );
3758 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3759 _surviving_young_words = NULL;
3760 }
3761
3762 #ifdef ASSERT
3763 class VerifyCSetClosure: public HeapRegionClosure {
3764 public:
3765 bool doHeapRegion(HeapRegion* hr) {
3766 // Here we check that the CSet region's RSet is ready for parallel
3767 // iteration. The fields that we'll verify are only manipulated
3768 // when the region is part of a CSet and is collected. Afterwards,
3769 // we reset these fields when we clear the region's RSet (when the
3770 // region is freed) so they are ready when the region is
3771 // re-allocated. The only exception to this is if there's an
3772 // evacuation failure and instead of freeing the region we leave
3773 // it in the heap. In that case, we reset these fields during
3774 // evacuation failure handling.
3775 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3776
3777 // Here's a good place to add any other checks we'd like to
3778 // perform on CSet regions.
3779 return false;
3780 }
3781 };
3782 #endif // ASSERT
3783
3784 #if TASKQUEUE_STATS
3785 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3786 st->print_raw_cr("GC Task Stats");
3787 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3788 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3789 }
3790
3791 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3792 print_taskqueue_stats_hdr(st);
3793
3794 TaskQueueStats totals;
3795 const int n = workers() != NULL ? workers()->total_workers() : 1;
3796 for (int i = 0; i < n; ++i) {
3797 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3798 totals += task_queue(i)->stats;
3799 }
3800 st->print_raw("tot "); totals.print(st); st->cr();
3801
3802 DEBUG_ONLY(totals.verify());
3803 }
3804
3805 void G1CollectedHeap::reset_taskqueue_stats() {
3806 const int n = workers() != NULL ? workers()->total_workers() : 1;
3807 for (int i = 0; i < n; ++i) {
3808 task_queue(i)->stats.reset();
3809 }
3810 }
3811 #endif // TASKQUEUE_STATS
3812
3813 void G1CollectedHeap::log_gc_header() {
3814 if (!G1Log::fine()) {
3815 return;
3816 }
3817
3818 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3819
3820 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3821 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3822 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3823
3824 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3825 }
3826
3827 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3828 if (!G1Log::fine()) {
3829 return;
3830 }
3831
3832 if (G1Log::finer()) {
3833 if (evacuation_failed()) {
3834 gclog_or_tty->print(" (to-space exhausted)");
3835 }
3836 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3837 g1_policy()->phase_times()->note_gc_end();
3838 g1_policy()->phase_times()->print(pause_time_sec);
3839 g1_policy()->print_detailed_heap_transition();
3840 } else {
3841 if (evacuation_failed()) {
3842 gclog_or_tty->print("--");
3843 }
3844 g1_policy()->print_heap_transition();
3845 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3846 }
3847 gclog_or_tty->flush();
3848 }
3849
3850 bool
3851 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3852 assert_at_safepoint(true /* should_be_vm_thread */);
3853 guarantee(!is_gc_active(), "collection is not reentrant");
3854
3855 if (GC_locker::check_active_before_gc()) {
3856 return false;
3857 }
3858
3859 _gc_timer_stw->register_gc_start();
3860
3861 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3862
3863 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3864 ResourceMark rm;
3865
3866 print_heap_before_gc();
3867 trace_heap_before_gc(_gc_tracer_stw);
3868
3869 verify_region_sets_optional();
3870 verify_dirty_young_regions();
3871
3872 // This call will decide whether this pause is an initial-mark
3873 // pause. If it is, during_initial_mark_pause() will return true
3874 // for the duration of this pause.
3875 g1_policy()->decide_on_conc_mark_initiation();
3876
3877 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3878 assert(!g1_policy()->during_initial_mark_pause() ||
3879 g1_policy()->gcs_are_young(), "sanity");
3880
3881 // We also do not allow mixed GCs during marking.
3882 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3883
3884 // Record whether this pause is an initial mark. When the current
3885 // thread has completed its logging output and it's safe to signal
3886 // the CM thread, the flag's value in the policy has been reset.
3887 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3888
3889 // Inner scope for scope based logging, timers, and stats collection
3890 {
3891 EvacuationInfo evacuation_info;
3892
3893 if (g1_policy()->during_initial_mark_pause()) {
3894 // We are about to start a marking cycle, so we increment the
3895 // full collection counter.
3896 increment_old_marking_cycles_started();
3897 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3898 }
3899
3900 _gc_tracer_stw->report_yc_type(yc_type());
3901
3902 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3903
3904 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3905 workers()->active_workers() : 1);
3906 double pause_start_sec = os::elapsedTime();
3907 g1_policy()->phase_times()->note_gc_start(active_workers);
3908 log_gc_header();
3909
3910 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3911 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3912
3913 // If the secondary_free_list is not empty, append it to the
3914 // free_list. No need to wait for the cleanup operation to finish;
3915 // the region allocation code will check the secondary_free_list
3916 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3917 // set, skip this step so that the region allocation code has to
3918 // get entries from the secondary_free_list.
3919 if (!G1StressConcRegionFreeing) {
3920 append_secondary_free_list_if_not_empty_with_lock();
3921 }
3922
3923 assert(check_young_list_well_formed(), "young list should be well formed");
3924 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3925 "sanity check");
3926
3927 // Don't dynamically change the number of GC threads this early. A value of
3928 // 0 is used to indicate serial work. When parallel work is done,
3929 // it will be set.
3930
3931 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3932 IsGCActiveMark x;
3933
3934 gc_prologue(false);
3935 increment_total_collections(false /* full gc */);
3936 increment_gc_time_stamp();
3937
3938 verify_before_gc();
3939 check_bitmaps("GC Start");
3940
3941 COMPILER2_PRESENT(DerivedPointerTable::clear());
3942
3943 // Please see comment in g1CollectedHeap.hpp and
3944 // G1CollectedHeap::ref_processing_init() to see how
3945 // reference processing currently works in G1.
3946
3947 // Enable discovery in the STW reference processor
3948 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3949 true /*verify_no_refs*/);
3950
3951 {
3952 // We want to temporarily turn off discovery by the
3953 // CM ref processor, if necessary, and turn it back on
3954 // on again later if we do. Using a scoped
3955 // NoRefDiscovery object will do this.
3956 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3957
3958 // Forget the current alloc region (we might even choose it to be part
3959 // of the collection set!).
3960 _allocator->release_mutator_alloc_region();
3961
3962 // We should call this after we retire the mutator alloc
3963 // region(s) so that all the ALLOC / RETIRE events are generated
3964 // before the start GC event.
3965 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3966
3967 // This timing is only used by the ergonomics to handle our pause target.
3968 // It is unclear why this should not include the full pause. We will
3969 // investigate this in CR 7178365.
3970 //
3971 // Preserving the old comment here if that helps the investigation:
3972 //
3973 // The elapsed time induced by the start time below deliberately elides
3974 // the possible verification above.
3975 double sample_start_time_sec = os::elapsedTime();
3976
3977 #if YOUNG_LIST_VERBOSE
3978 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3979 _young_list->print();
3980 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3981 #endif // YOUNG_LIST_VERBOSE
3982
3983 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3984
3985 double scan_wait_start = os::elapsedTime();
3986 // We have to wait until the CM threads finish scanning the
3987 // root regions as it's the only way to ensure that all the
3988 // objects on them have been correctly scanned before we start
3989 // moving them during the GC.
3990 bool waited = _cm->root_regions()->wait_until_scan_finished();
3991 double wait_time_ms = 0.0;
3992 if (waited) {
3993 double scan_wait_end = os::elapsedTime();
3994 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3995 }
3996 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3997
3998 #if YOUNG_LIST_VERBOSE
3999 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4000 _young_list->print();
4001 #endif // YOUNG_LIST_VERBOSE
4002
4003 if (g1_policy()->during_initial_mark_pause()) {
4004 concurrent_mark()->checkpointRootsInitialPre();
4005 }
4006
4007 #if YOUNG_LIST_VERBOSE
4008 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4009 _young_list->print();
4010 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4011 #endif // YOUNG_LIST_VERBOSE
4012
4013 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4014
4015 register_humongous_regions_with_in_cset_fast_test();
4016
4017 _cm->note_start_of_gc();
4018 // We should not verify the per-thread SATB buffers given that
4019 // we have not filtered them yet (we'll do so during the
4020 // GC). We also call this after finalize_cset() to
4021 // ensure that the CSet has been finalized.
4022 _cm->verify_no_cset_oops(true /* verify_stacks */,
4023 true /* verify_enqueued_buffers */,
4024 false /* verify_thread_buffers */,
4025 true /* verify_fingers */);
4026
4027 if (_hr_printer.is_active()) {
4028 HeapRegion* hr = g1_policy()->collection_set();
4029 while (hr != NULL) {
4030 _hr_printer.cset(hr);
4031 hr = hr->next_in_collection_set();
4032 }
4033 }
4034
4035 #ifdef ASSERT
4036 VerifyCSetClosure cl;
4037 collection_set_iterate(&cl);
4038 #endif // ASSERT
4039
4040 setup_surviving_young_words();
4041
4042 // Initialize the GC alloc regions.
4043 _allocator->init_gc_alloc_regions(evacuation_info);
4044
4045 // Actually do the work...
4046 evacuate_collection_set(evacuation_info);
4047
4048 // We do this to mainly verify the per-thread SATB buffers
4049 // (which have been filtered by now) since we didn't verify
4050 // them earlier. No point in re-checking the stacks / enqueued
4051 // buffers given that the CSet has not changed since last time
4052 // we checked.
4053 _cm->verify_no_cset_oops(false /* verify_stacks */,
4054 false /* verify_enqueued_buffers */,
4055 true /* verify_thread_buffers */,
4056 true /* verify_fingers */);
4057
4058 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4059
4060 eagerly_reclaim_humongous_regions();
4061
4062 g1_policy()->clear_collection_set();
4063
4064 cleanup_surviving_young_words();
4065
4066 // Start a new incremental collection set for the next pause.
4067 g1_policy()->start_incremental_cset_building();
4068
4069 clear_cset_fast_test();
4070
4071 _young_list->reset_sampled_info();
4072
4073 // Don't check the whole heap at this point as the
4074 // GC alloc regions from this pause have been tagged
4075 // as survivors and moved on to the survivor list.
4076 // Survivor regions will fail the !is_young() check.
4077 assert(check_young_list_empty(false /* check_heap */),
4078 "young list should be empty");
4079
4080 #if YOUNG_LIST_VERBOSE
4081 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4082 _young_list->print();
4083 #endif // YOUNG_LIST_VERBOSE
4084
4085 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4086 _young_list->first_survivor_region(),
4087 _young_list->last_survivor_region());
4088
4089 _young_list->reset_auxilary_lists();
4090
4091 if (evacuation_failed()) {
4092 _allocator->set_used(recalculate_used());
4093 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4094 for (uint i = 0; i < n_queues; i++) {
4095 if (_evacuation_failed_info_array[i].has_failed()) {
4096 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4097 }
4098 }
4099 } else {
4100 // The "used" of the the collection set have already been subtracted
4101 // when they were freed. Add in the bytes evacuated.
4102 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4103 }
4104
4105 if (g1_policy()->during_initial_mark_pause()) {
4106 // We have to do this before we notify the CM threads that
4107 // they can start working to make sure that all the
4108 // appropriate initialization is done on the CM object.
4109 concurrent_mark()->checkpointRootsInitialPost();
4110 set_marking_started();
4111 // Note that we don't actually trigger the CM thread at
4112 // this point. We do that later when we're sure that
4113 // the current thread has completed its logging output.
4114 }
4115
4116 allocate_dummy_regions();
4117
4118 #if YOUNG_LIST_VERBOSE
4119 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4120 _young_list->print();
4121 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4122 #endif // YOUNG_LIST_VERBOSE
4123
4124 _allocator->init_mutator_alloc_region();
4125
4126 {
4127 size_t expand_bytes = g1_policy()->expansion_amount();
4128 if (expand_bytes > 0) {
4129 size_t bytes_before = capacity();
4130 // No need for an ergo verbose message here,
4131 // expansion_amount() does this when it returns a value > 0.
4132 if (!expand(expand_bytes)) {
4133 // We failed to expand the heap. Cannot do anything about it.
4134 }
4135 }
4136 }
4137
4138 // We redo the verification but now wrt to the new CSet which
4139 // has just got initialized after the previous CSet was freed.
4140 _cm->verify_no_cset_oops(true /* verify_stacks */,
4141 true /* verify_enqueued_buffers */,
4142 true /* verify_thread_buffers */,
4143 true /* verify_fingers */);
4144 _cm->note_end_of_gc();
4145
4146 // This timing is only used by the ergonomics to handle our pause target.
4147 // It is unclear why this should not include the full pause. We will
4148 // investigate this in CR 7178365.
4149 double sample_end_time_sec = os::elapsedTime();
4150 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4151 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4152
4153 MemoryService::track_memory_usage();
4154
4155 // In prepare_for_verify() below we'll need to scan the deferred
4156 // update buffers to bring the RSets up-to-date if
4157 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4158 // the update buffers we'll probably need to scan cards on the
4159 // regions we just allocated to (i.e., the GC alloc
4160 // regions). However, during the last GC we called
4161 // set_saved_mark() on all the GC alloc regions, so card
4162 // scanning might skip the [saved_mark_word()...top()] area of
4163 // those regions (i.e., the area we allocated objects into
4164 // during the last GC). But it shouldn't. Given that
4165 // saved_mark_word() is conditional on whether the GC time stamp
4166 // on the region is current or not, by incrementing the GC time
4167 // stamp here we invalidate all the GC time stamps on all the
4168 // regions and saved_mark_word() will simply return top() for
4169 // all the regions. This is a nicer way of ensuring this rather
4170 // than iterating over the regions and fixing them. In fact, the
4171 // GC time stamp increment here also ensures that
4172 // saved_mark_word() will return top() between pauses, i.e.,
4173 // during concurrent refinement. So we don't need the
4174 // is_gc_active() check to decided which top to use when
4175 // scanning cards (see CR 7039627).
4176 increment_gc_time_stamp();
4177
4178 verify_after_gc();
4179 check_bitmaps("GC End");
4180
4181 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4182 ref_processor_stw()->verify_no_references_recorded();
4183
4184 // CM reference discovery will be re-enabled if necessary.
4185 }
4186
4187 // We should do this after we potentially expand the heap so
4188 // that all the COMMIT events are generated before the end GC
4189 // event, and after we retire the GC alloc regions so that all
4190 // RETIRE events are generated before the end GC event.
4191 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4192
4193 #ifdef TRACESPINNING
4194 ParallelTaskTerminator::print_termination_counts();
4195 #endif
4196
4197 gc_epilogue(false);
4198 }
4199
4200 // Print the remainder of the GC log output.
4201 log_gc_footer(os::elapsedTime() - pause_start_sec);
4202
4203 // It is not yet to safe to tell the concurrent mark to
4204 // start as we have some optional output below. We don't want the
4205 // output from the concurrent mark thread interfering with this
4206 // logging output either.
4207
4208 _hrm.verify_optional();
4209 verify_region_sets_optional();
4210
4211 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4212 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4213
4214 print_heap_after_gc();
4215 trace_heap_after_gc(_gc_tracer_stw);
4216
4217 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4218 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4219 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4220 // before any GC notifications are raised.
4221 g1mm()->update_sizes();
4222
4223 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4224 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4225 _gc_timer_stw->register_gc_end();
4226 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4227 }
4228 // It should now be safe to tell the concurrent mark thread to start
4229 // without its logging output interfering with the logging output
4230 // that came from the pause.
4231
4232 if (should_start_conc_mark) {
4233 // CAUTION: after the doConcurrentMark() call below,
4234 // the concurrent marking thread(s) could be running
4235 // concurrently with us. Make sure that anything after
4236 // this point does not assume that we are the only GC thread
4237 // running. Note: of course, the actual marking work will
4238 // not start until the safepoint itself is released in
4239 // SuspendibleThreadSet::desynchronize().
4240 doConcurrentMark();
4241 }
4242
4243 return true;
4244 }
4245
4246 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4247 {
4248 size_t gclab_word_size;
4249 switch (purpose) {
4250 case GCAllocForSurvived:
4251 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4252 break;
4253 case GCAllocForTenured:
4254 gclab_word_size = _old_plab_stats.desired_plab_sz();
4255 break;
4256 default:
4257 assert(false, "unknown GCAllocPurpose");
4258 gclab_word_size = _old_plab_stats.desired_plab_sz();
4259 break;
4260 }
4261
4262 // Prevent humongous PLAB sizes for two reasons:
4263 // * PLABs are allocated using a similar paths as oops, but should
4264 // never be in a humongous region
4265 // * Allowing humongous PLABs needlessly churns the region free lists
4266 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4267 }
4268
4269 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4270 _drain_in_progress = false;
4271 set_evac_failure_closure(cl);
4272 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4273 }
4274
4275 void G1CollectedHeap::finalize_for_evac_failure() {
4276 assert(_evac_failure_scan_stack != NULL &&
4277 _evac_failure_scan_stack->length() == 0,
4278 "Postcondition");
4279 assert(!_drain_in_progress, "Postcondition");
4280 delete _evac_failure_scan_stack;
4281 _evac_failure_scan_stack = NULL;
4282 }
4283
4284 void G1CollectedHeap::remove_self_forwarding_pointers() {
4285 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4286
4287 double remove_self_forwards_start = os::elapsedTime();
4288
4289 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4290
4291 if (G1CollectedHeap::use_parallel_gc_threads()) {
4292 set_par_threads();
4293 workers()->run_task(&rsfp_task);
4294 set_par_threads(0);
4295 } else {
4296 rsfp_task.work(0);
4297 }
4298
4299 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4300
4301 // Reset the claim values in the regions in the collection set.
4302 reset_cset_heap_region_claim_values();
4303
4304 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4305
4306 // Now restore saved marks, if any.
4307 assert(_objs_with_preserved_marks.size() ==
4308 _preserved_marks_of_objs.size(), "Both or none.");
4309 while (!_objs_with_preserved_marks.is_empty()) {
4310 oop obj = _objs_with_preserved_marks.pop();
4311 markOop m = _preserved_marks_of_objs.pop();
4312 obj->set_mark(m);
4313 }
4314 _objs_with_preserved_marks.clear(true);
4315 _preserved_marks_of_objs.clear(true);
4316
4317 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4318 }
4319
4320 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4321 _evac_failure_scan_stack->push(obj);
4322 }
4323
4324 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4325 assert(_evac_failure_scan_stack != NULL, "precondition");
4326
4327 while (_evac_failure_scan_stack->length() > 0) {
4328 oop obj = _evac_failure_scan_stack->pop();
4329 _evac_failure_closure->set_region(heap_region_containing(obj));
4330 obj->oop_iterate_backwards(_evac_failure_closure);
4331 }
4332 }
4333
4334 oop
4335 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4336 oop old) {
4337 assert(obj_in_cs(old),
4338 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4339 (HeapWord*) old));
4340 markOop m = old->mark();
4341 oop forward_ptr = old->forward_to_atomic(old);
4342 if (forward_ptr == NULL) {
4343 // Forward-to-self succeeded.
4344 assert(_par_scan_state != NULL, "par scan state");
4345 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4346 uint queue_num = _par_scan_state->queue_num();
4347
4348 _evacuation_failed = true;
4349 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4350 if (_evac_failure_closure != cl) {
4351 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4352 assert(!_drain_in_progress,
4353 "Should only be true while someone holds the lock.");
4354 // Set the global evac-failure closure to the current thread's.
4355 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4356 set_evac_failure_closure(cl);
4357 // Now do the common part.
4358 handle_evacuation_failure_common(old, m);
4359 // Reset to NULL.
4360 set_evac_failure_closure(NULL);
4361 } else {
4362 // The lock is already held, and this is recursive.
4363 assert(_drain_in_progress, "This should only be the recursive case.");
4364 handle_evacuation_failure_common(old, m);
4365 }
4366 return old;
4367 } else {
4368 // Forward-to-self failed. Either someone else managed to allocate
4369 // space for this object (old != forward_ptr) or they beat us in
4370 // self-forwarding it (old == forward_ptr).
4371 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4372 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4373 "should not be in the CSet",
4374 (HeapWord*) old, (HeapWord*) forward_ptr));
4375 return forward_ptr;
4376 }
4377 }
4378
4379 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4380 preserve_mark_if_necessary(old, m);
4381
4382 HeapRegion* r = heap_region_containing(old);
4383 if (!r->evacuation_failed()) {
4384 r->set_evacuation_failed(true);
4385 _hr_printer.evac_failure(r);
4386 }
4387
4388 push_on_evac_failure_scan_stack(old);
4389
4390 if (!_drain_in_progress) {
4391 // prevent recursion in copy_to_survivor_space()
4392 _drain_in_progress = true;
4393 drain_evac_failure_scan_stack();
4394 _drain_in_progress = false;
4395 }
4396 }
4397
4398 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4399 assert(evacuation_failed(), "Oversaving!");
4400 // We want to call the "for_promotion_failure" version only in the
4401 // case of a promotion failure.
4402 if (m->must_be_preserved_for_promotion_failure(obj)) {
4403 _objs_with_preserved_marks.push(obj);
4404 _preserved_marks_of_objs.push(m);
4405 }
4406 }
4407
4408 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4409 size_t word_size,
4410 AllocationContext_t context) {
4411 if (purpose == GCAllocForSurvived) {
4412 HeapWord* result = survivor_attempt_allocation(word_size, context);
4413 if (result != NULL) {
4414 return result;
4415 } else {
4416 // Let's try to allocate in the old gen in case we can fit the
4417 // object there.
4418 return old_attempt_allocation(word_size, context);
4419 }
4420 } else {
4421 assert(purpose == GCAllocForTenured, "sanity");
4422 HeapWord* result = old_attempt_allocation(word_size, context);
4423 if (result != NULL) {
4424 return result;
4425 } else {
4426 // Let's try to allocate in the survivors in case we can fit the
4427 // object there.
4428 return survivor_attempt_allocation(word_size, context);
4429 }
4430 }
4431
4432 ShouldNotReachHere();
4433 // Trying to keep some compilers happy.
4434 return NULL;
4435 }
4436
4437 void G1ParCopyHelper::mark_object(oop obj) {
4438 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4439
4440 // We know that the object is not moving so it's safe to read its size.
4441 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4442 }
4443
4444 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4445 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4446 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4447 assert(from_obj != to_obj, "should not be self-forwarded");
4448
4449 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4450 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4451
4452 // The object might be in the process of being copied by another
4453 // worker so we cannot trust that its to-space image is
4454 // well-formed. So we have to read its size from its from-space
4455 // image which we know should not be changing.
4456 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4457 }
4458
4459 template <class T>
4460 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4461 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4462 _scanned_klass->record_modified_oops();
4463 }
4464 }
4465
4466 template <G1Barrier barrier, G1Mark do_mark_object>
4467 template <class T>
4468 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4469 T heap_oop = oopDesc::load_heap_oop(p);
4470
4471 if (oopDesc::is_null(heap_oop)) {
4472 return;
4473 }
4474
4475 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4476
4477 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4478
4479 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4480
4481 if (state == G1CollectedHeap::InCSet) {
4482 oop forwardee;
4483 if (obj->is_forwarded()) {
4484 forwardee = obj->forwardee();
4485 } else {
4486 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4487 }
4488 assert(forwardee != NULL, "forwardee should not be NULL");
4489 oopDesc::encode_store_heap_oop(p, forwardee);
4490 if (do_mark_object != G1MarkNone && forwardee != obj) {
4491 // If the object is self-forwarded we don't need to explicitly
4492 // mark it, the evacuation failure protocol will do so.
4493 mark_forwarded_object(obj, forwardee);
4494 }
4495
4496 if (barrier == G1BarrierKlass) {
4497 do_klass_barrier(p, forwardee);
4498 }
4499 } else {
4500 if (state == G1CollectedHeap::IsHumongous) {
4501 _g1->set_humongous_is_live(obj);
4502 }
4503 // The object is not in collection set. If we're a root scanning
4504 // closure during an initial mark pause then attempt to mark the object.
4505 if (do_mark_object == G1MarkFromRoot) {
4506 mark_object(obj);
4507 }
4508 }
4509
4510 if (barrier == G1BarrierEvac) {
4511 _par_scan_state->update_rs(_from, p, _worker_id);
4512 }
4513 }
4514
4515 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4516 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4517
4518 class G1ParEvacuateFollowersClosure : public VoidClosure {
4519 protected:
4520 G1CollectedHeap* _g1h;
4521 G1ParScanThreadState* _par_scan_state;
4522 RefToScanQueueSet* _queues;
4523 ParallelTaskTerminator* _terminator;
4524
4525 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4526 RefToScanQueueSet* queues() { return _queues; }
4527 ParallelTaskTerminator* terminator() { return _terminator; }
4528
4529 public:
4530 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4531 G1ParScanThreadState* par_scan_state,
4532 RefToScanQueueSet* queues,
4533 ParallelTaskTerminator* terminator)
4534 : _g1h(g1h), _par_scan_state(par_scan_state),
4535 _queues(queues), _terminator(terminator) {}
4536
4537 void do_void();
4538
4539 private:
4540 inline bool offer_termination();
4541 };
4542
4543 bool G1ParEvacuateFollowersClosure::offer_termination() {
4544 G1ParScanThreadState* const pss = par_scan_state();
4545 pss->start_term_time();
4546 const bool res = terminator()->offer_termination();
4547 pss->end_term_time();
4548 return res;
4549 }
4550
4551 void G1ParEvacuateFollowersClosure::do_void() {
4552 G1ParScanThreadState* const pss = par_scan_state();
4553 pss->trim_queue();
4554 do {
4555 pss->steal_and_trim_queue(queues());
4556 } while (!offer_termination());
4557 }
4558
4559 class G1KlassScanClosure : public KlassClosure {
4560 G1ParCopyHelper* _closure;
4561 bool _process_only_dirty;
4562 int _count;
4563 public:
4564 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4565 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4566 void do_klass(Klass* klass) {
4567 // If the klass has not been dirtied we know that there's
4568 // no references into the young gen and we can skip it.
4569 if (!_process_only_dirty || klass->has_modified_oops()) {
4570 // Clean the klass since we're going to scavenge all the metadata.
4571 klass->clear_modified_oops();
4572
4573 // Tell the closure that this klass is the Klass to scavenge
4574 // and is the one to dirty if oops are left pointing into the young gen.
4575 _closure->set_scanned_klass(klass);
4576
4577 klass->oops_do(_closure);
4578
4579 _closure->set_scanned_klass(NULL);
4580 }
4581 _count++;
4582 }
4583 };
4584
4585 class G1CodeBlobClosure : public CodeBlobClosure {
4586 class HeapRegionGatheringOopClosure : public OopClosure {
4587 G1CollectedHeap* _g1h;
4588 OopClosure* _work;
4589 nmethod* _nm;
4590
4591 template <typename T>
4592 void do_oop_work(T* p) {
4593 _work->do_oop(p);
4594 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4595 if (!oopDesc::is_null(oop_or_narrowoop)) {
4596 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4597 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4598 assert(!_g1h->obj_in_cs(o) || hr->rem_set()->strong_code_roots_list_contains(_nm), "if o still in CS then evacuation failed and nm must already be in the remset");
4599 hr->add_strong_code_root(_nm);
4600 }
4601 }
4602
4603 public:
4604 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4605
4606 void do_oop(oop* o) {
4607 do_oop_work(o);
4608 }
4609
4610 void do_oop(narrowOop* o) {
4611 do_oop_work(o);
4612 }
4613
4614 void set_nm(nmethod* nm) {
4615 _nm = nm;
4616 }
4617 };
4618
4619 HeapRegionGatheringOopClosure _oc;
4620 public:
4621 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4622
4623 void do_code_blob(CodeBlob* cb) {
4624 nmethod* nm = cb->as_nmethod_or_null();
4625 if (nm != NULL) {
4626 if (!nm->test_set_oops_do_mark()) {
4627 _oc.set_nm(nm);
4628 nm->oops_do(&_oc);
4629 nm->fix_oop_relocations();
4630 }
4631 }
4632 }
4633 };
4634
4635 class G1ParTask : public AbstractGangTask {
4636 protected:
4637 G1CollectedHeap* _g1h;
4638 RefToScanQueueSet *_queues;
4639 ParallelTaskTerminator _terminator;
4640 uint _n_workers;
4641
4642 Mutex _stats_lock;
4643 Mutex* stats_lock() { return &_stats_lock; }
4644
4645 public:
4646 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4647 : AbstractGangTask("G1 collection"),
4648 _g1h(g1h),
4649 _queues(task_queues),
4650 _terminator(0, _queues),
4651 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4652 {}
4653
4654 RefToScanQueueSet* queues() { return _queues; }
4655
4656 RefToScanQueue *work_queue(int i) {
4657 return queues()->queue(i);
4658 }
4659
4660 ParallelTaskTerminator* terminator() { return &_terminator; }
4661
4662 virtual void set_for_termination(int active_workers) {
4663 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4664 // in the young space (_par_seq_tasks) in the G1 heap
4665 // for SequentialSubTasksDone.
4666 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4667 // both of which need setting by set_n_termination().
4668 _g1h->SharedHeap::set_n_termination(active_workers);
4669 _g1h->set_n_termination(active_workers);
4670 terminator()->reset_for_reuse(active_workers);
4671 _n_workers = active_workers;
4672 }
4673
4674 // Helps out with CLD processing.
4675 //
4676 // During InitialMark we need to:
4677 // 1) Scavenge all CLDs for the young GC.
4678 // 2) Mark all objects directly reachable from strong CLDs.
4679 template <G1Mark do_mark_object>
4680 class G1CLDClosure : public CLDClosure {
4681 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4682 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4683 G1KlassScanClosure _klass_in_cld_closure;
4684 bool _claim;
4685
4686 public:
4687 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4688 bool only_young, bool claim)
4689 : _oop_closure(oop_closure),
4690 _oop_in_klass_closure(oop_closure->g1(),
4691 oop_closure->pss(),
4692 oop_closure->rp()),
4693 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4694 _claim(claim) {
4695
4696 }
4697
4698 void do_cld(ClassLoaderData* cld) {
4699 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4700 }
4701 };
4702
4703 void work(uint worker_id) {
4704 if (worker_id >= _n_workers) return; // no work needed this round
4705
4706 double start_time_ms = os::elapsedTime() * 1000.0;
4707 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4708
4709 {
4710 ResourceMark rm;
4711 HandleMark hm;
4712
4713 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4714
4715 G1ParScanThreadState pss(_g1h, worker_id, rp);
4716 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4717
4718 pss.set_evac_failure_closure(&evac_failure_cl);
4719
4720 bool only_young = _g1h->g1_policy()->gcs_are_young();
4721
4722 // Non-IM young GC.
4723 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4724 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4725 only_young, // Only process dirty klasses.
4726 false); // No need to claim CLDs.
4727 // IM young GC.
4728 // Strong roots closures.
4729 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4730 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4731 false, // Process all klasses.
4732 true); // Need to claim CLDs.
4733 // Weak roots closures.
4734 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4735 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4736 false, // Process all klasses.
4737 true); // Need to claim CLDs.
4738
4739 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4740 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4741 // IM Weak code roots are handled later.
4742
4743 OopClosure* strong_root_cl;
4744 OopClosure* weak_root_cl;
4745 CLDClosure* strong_cld_cl;
4746 CLDClosure* weak_cld_cl;
4747 CodeBlobClosure* strong_code_cl;
4748
4749 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4750 // We also need to mark copied objects.
4751 strong_root_cl = &scan_mark_root_cl;
4752 strong_cld_cl = &scan_mark_cld_cl;
4753 strong_code_cl = &scan_mark_code_cl;
4754 if (ClassUnloadingWithConcurrentMark) {
4755 weak_root_cl = &scan_mark_weak_root_cl;
4756 weak_cld_cl = &scan_mark_weak_cld_cl;
4757 } else {
4758 weak_root_cl = &scan_mark_root_cl;
4759 weak_cld_cl = &scan_mark_cld_cl;
4760 }
4761 } else {
4762 strong_root_cl = &scan_only_root_cl;
4763 weak_root_cl = &scan_only_root_cl;
4764 strong_cld_cl = &scan_only_cld_cl;
4765 weak_cld_cl = &scan_only_cld_cl;
4766 strong_code_cl = &scan_only_code_cl;
4767 }
4768
4769
4770 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4771
4772 pss.start_strong_roots();
4773 _g1h->g1_process_roots(strong_root_cl,
4774 weak_root_cl,
4775 &push_heap_rs_cl,
4776 strong_cld_cl,
4777 weak_cld_cl,
4778 strong_code_cl,
4779 worker_id);
4780
4781 pss.end_strong_roots();
4782
4783 {
4784 double start = os::elapsedTime();
4785 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4786 evac.do_void();
4787 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4788 double term_ms = pss.term_time()*1000.0;
4789 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4790 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4791 }
4792 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4793 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4794
4795 if (ParallelGCVerbose) {
4796 MutexLocker x(stats_lock());
4797 pss.print_termination_stats(worker_id);
4798 }
4799
4800 assert(pss.queue_is_empty(), "should be empty");
4801
4802 // Close the inner scope so that the ResourceMark and HandleMark
4803 // destructors are executed here and are included as part of the
4804 // "GC Worker Time".
4805 }
4806
4807 double end_time_ms = os::elapsedTime() * 1000.0;
4808 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4809 }
4810 };
4811
4812 // *** Common G1 Evacuation Stuff
4813
4814 // This method is run in a GC worker.
4815
4816 void
4817 G1CollectedHeap::
4818 g1_process_roots(OopClosure* scan_non_heap_roots,
4819 OopClosure* scan_non_heap_weak_roots,
4820 OopsInHeapRegionClosure* scan_rs,
4821 CLDClosure* scan_strong_clds,
4822 CLDClosure* scan_weak_clds,
4823 CodeBlobClosure* scan_strong_code,
4824 uint worker_i) {
4825
4826 // First scan the shared roots.
4827 double ext_roots_start = os::elapsedTime();
4828 double closure_app_time_sec = 0.0;
4829
4830 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4831 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4832
4833 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4834 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4835
4836 process_roots(false, // no scoping; this is parallel code
4837 SharedHeap::SO_None,
4838 &buf_scan_non_heap_roots,
4839 &buf_scan_non_heap_weak_roots,
4840 scan_strong_clds,
4841 // Unloading Initial Marks handle the weak CLDs separately.
4842 (trace_metadata ? NULL : scan_weak_clds),
4843 scan_strong_code);
4844
4845 // Now the CM ref_processor roots.
4846 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4847 // We need to treat the discovered reference lists of the
4848 // concurrent mark ref processor as roots and keep entries
4849 // (which are added by the marking threads) on them live
4850 // until they can be processed at the end of marking.
4851 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4852 }
4853
4854 if (trace_metadata) {
4855 // Barrier to make sure all workers passed
4856 // the strong CLD and strong nmethods phases.
4857 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4858
4859 // Now take the complement of the strong CLDs.
4860 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4861 }
4862
4863 // Finish up any enqueued closure apps (attributed as object copy time).
4864 buf_scan_non_heap_roots.done();
4865 buf_scan_non_heap_weak_roots.done();
4866
4867 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4868 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4869
4870 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4871
4872 double ext_root_time_ms =
4873 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4874
4875 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4876
4877 // During conc marking we have to filter the per-thread SATB buffers
4878 // to make sure we remove any oops into the CSet (which will show up
4879 // as implicitly live).
4880 double satb_filtering_ms = 0.0;
4881 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4882 if (mark_in_progress()) {
4883 double satb_filter_start = os::elapsedTime();
4884
4885 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4886
4887 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4888 }
4889 }
4890 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4891
4892 // Now scan the complement of the collection set.
4893 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4894
4895 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4896
4897 _process_strong_tasks->all_tasks_completed();
4898 }
4899
4900 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4901 private:
4902 BoolObjectClosure* _is_alive;
4903 int _initial_string_table_size;
4904 int _initial_symbol_table_size;
4905
4906 bool _process_strings;
4907 int _strings_processed;
4908 int _strings_removed;
4909
4910 bool _process_symbols;
4911 int _symbols_processed;
4912 int _symbols_removed;
4913
4914 bool _do_in_parallel;
4915 public:
4916 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4917 AbstractGangTask("String/Symbol Unlinking"),
4918 _is_alive(is_alive),
4919 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4920 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4921 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4922
4923 _initial_string_table_size = StringTable::the_table()->table_size();
4924 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4925 if (process_strings) {
4926 StringTable::clear_parallel_claimed_index();
4927 }
4928 if (process_symbols) {
4929 SymbolTable::clear_parallel_claimed_index();
4930 }
4931 }
4932
4933 ~G1StringSymbolTableUnlinkTask() {
4934 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4935 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4936 StringTable::parallel_claimed_index(), _initial_string_table_size));
4937 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4938 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4939 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4940
4941 if (G1TraceStringSymbolTableScrubbing) {
4942 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4943 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4944 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4945 strings_processed(), strings_removed(),
4946 symbols_processed(), symbols_removed());
4947 }
4948 }
4949
4950 void work(uint worker_id) {
4951 if (_do_in_parallel) {
4952 int strings_processed = 0;
4953 int strings_removed = 0;
4954 int symbols_processed = 0;
4955 int symbols_removed = 0;
4956 if (_process_strings) {
4957 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4958 Atomic::add(strings_processed, &_strings_processed);
4959 Atomic::add(strings_removed, &_strings_removed);
4960 }
4961 if (_process_symbols) {
4962 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4963 Atomic::add(symbols_processed, &_symbols_processed);
4964 Atomic::add(symbols_removed, &_symbols_removed);
4965 }
4966 } else {
4967 if (_process_strings) {
4968 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
4969 }
4970 if (_process_symbols) {
4971 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
4972 }
4973 }
4974 }
4975
4976 size_t strings_processed() const { return (size_t)_strings_processed; }
4977 size_t strings_removed() const { return (size_t)_strings_removed; }
4978
4979 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4980 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4981 };
4982
4983 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4984 private:
4985 static Monitor* _lock;
4986
4987 BoolObjectClosure* const _is_alive;
4988 const bool _unloading_occurred;
4989 const uint _num_workers;
4990
4991 // Variables used to claim nmethods.
4992 nmethod* _first_nmethod;
4993 volatile nmethod* _claimed_nmethod;
4994
4995 // The list of nmethods that need to be processed by the second pass.
4996 volatile nmethod* _postponed_list;
4997 volatile uint _num_entered_barrier;
4998
4999 public:
5000 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
5001 _is_alive(is_alive),
5002 _unloading_occurred(unloading_occurred),
5003 _num_workers(num_workers),
5004 _first_nmethod(NULL),
5005 _claimed_nmethod(NULL),
5006 _postponed_list(NULL),
5007 _num_entered_barrier(0)
5008 {
5009 nmethod::increase_unloading_clock();
5010 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
5011 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
5012 }
5013
5014 ~G1CodeCacheUnloadingTask() {
5015 CodeCache::verify_clean_inline_caches();
5016
5017 CodeCache::set_needs_cache_clean(false);
5018 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
5019
5020 CodeCache::verify_icholder_relocations();
5021 }
5022
5023 private:
5024 void add_to_postponed_list(nmethod* nm) {
5025 nmethod* old;
5026 do {
5027 old = (nmethod*)_postponed_list;
5028 nm->set_unloading_next(old);
5029 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
5030 }
5031
5032 void clean_nmethod(nmethod* nm) {
5033 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
5034
5035 if (postponed) {
5036 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
5037 add_to_postponed_list(nm);
5038 }
5039
5040 // Mark that this thread has been cleaned/unloaded.
5041 // After this call, it will be safe to ask if this nmethod was unloaded or not.
5042 nm->set_unloading_clock(nmethod::global_unloading_clock());
5043 }
5044
5045 void clean_nmethod_postponed(nmethod* nm) {
5046 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
5047 }
5048
5049 static const int MaxClaimNmethods = 16;
5050
5051 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
5052 nmethod* first;
5053 nmethod* last;
5054
5055 do {
5056 *num_claimed_nmethods = 0;
5057
5058 first = last = (nmethod*)_claimed_nmethod;
5059
5060 if (first != NULL) {
5061 for (int i = 0; i < MaxClaimNmethods; i++) {
5062 last = CodeCache::alive_nmethod(CodeCache::next(last));
5063
5064 if (last == NULL) {
5065 break;
5066 }
5067
5068 claimed_nmethods[i] = last;
5069 (*num_claimed_nmethods)++;
5070 }
5071 }
5072
5073 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
5074 }
5075
5076 nmethod* claim_postponed_nmethod() {
5077 nmethod* claim;
5078 nmethod* next;
5079
5080 do {
5081 claim = (nmethod*)_postponed_list;
5082 if (claim == NULL) {
5083 return NULL;
5084 }
5085
5086 next = claim->unloading_next();
5087
5088 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
5089
5090 return claim;
5091 }
5092
5093 public:
5094 // Mark that we're done with the first pass of nmethod cleaning.
5095 void barrier_mark(uint worker_id) {
5096 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5097 _num_entered_barrier++;
5098 if (_num_entered_barrier == _num_workers) {
5099 ml.notify_all();
5100 }
5101 }
5102
5103 // See if we have to wait for the other workers to
5104 // finish their first-pass nmethod cleaning work.
5105 void barrier_wait(uint worker_id) {
5106 if (_num_entered_barrier < _num_workers) {
5107 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5108 while (_num_entered_barrier < _num_workers) {
5109 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5110 }
5111 }
5112 }
5113
5114 // Cleaning and unloading of nmethods. Some work has to be postponed
5115 // to the second pass, when we know which nmethods survive.
5116 void work_first_pass(uint worker_id) {
5117 // The first nmethods is claimed by the first worker.
5118 if (worker_id == 0 && _first_nmethod != NULL) {
5119 clean_nmethod(_first_nmethod);
5120 _first_nmethod = NULL;
5121 }
5122
5123 int num_claimed_nmethods;
5124 nmethod* claimed_nmethods[MaxClaimNmethods];
5125
5126 while (true) {
5127 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5128
5129 if (num_claimed_nmethods == 0) {
5130 break;
5131 }
5132
5133 for (int i = 0; i < num_claimed_nmethods; i++) {
5134 clean_nmethod(claimed_nmethods[i]);
5135 }
5136 }
5137
5138 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
5139 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
5140 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
5141 }
5142
5143 void work_second_pass(uint worker_id) {
5144 nmethod* nm;
5145 // Take care of postponed nmethods.
5146 while ((nm = claim_postponed_nmethod()) != NULL) {
5147 clean_nmethod_postponed(nm);
5148 }
5149 }
5150 };
5151
5152 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5153
5154 class G1KlassCleaningTask : public StackObj {
5155 BoolObjectClosure* _is_alive;
5156 volatile jint _clean_klass_tree_claimed;
5157 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5158
5159 public:
5160 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5161 _is_alive(is_alive),
5162 _clean_klass_tree_claimed(0),
5163 _klass_iterator() {
5164 }
5165
5166 private:
5167 bool claim_clean_klass_tree_task() {
5168 if (_clean_klass_tree_claimed) {
5169 return false;
5170 }
5171
5172 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5173 }
5174
5175 InstanceKlass* claim_next_klass() {
5176 Klass* klass;
5177 do {
5178 klass =_klass_iterator.next_klass();
5179 } while (klass != NULL && !klass->oop_is_instance());
5180
5181 return (InstanceKlass*)klass;
5182 }
5183
5184 public:
5185
5186 void clean_klass(InstanceKlass* ik) {
5187 ik->clean_implementors_list(_is_alive);
5188 ik->clean_method_data(_is_alive);
5189
5190 // G1 specific cleanup work that has
5191 // been moved here to be done in parallel.
5192 ik->clean_dependent_nmethods();
5193 if (JvmtiExport::has_redefined_a_class()) {
5194 InstanceKlass::purge_previous_versions(ik);
5195 }
5196 }
5197
5198 void work() {
5199 ResourceMark rm;
5200
5201 // One worker will clean the subklass/sibling klass tree.
5202 if (claim_clean_klass_tree_task()) {
5203 Klass::clean_subklass_tree(_is_alive);
5204 }
5205
5206 // All workers will help cleaning the classes,
5207 InstanceKlass* klass;
5208 while ((klass = claim_next_klass()) != NULL) {
5209 clean_klass(klass);
5210 }
5211 }
5212 };
5213
5214 // To minimize the remark pause times, the tasks below are done in parallel.
5215 class G1ParallelCleaningTask : public AbstractGangTask {
5216 private:
5217 G1StringSymbolTableUnlinkTask _string_symbol_task;
5218 G1CodeCacheUnloadingTask _code_cache_task;
5219 G1KlassCleaningTask _klass_cleaning_task;
5220
5221 public:
5222 // The constructor is run in the VMThread.
5223 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5224 AbstractGangTask("Parallel Cleaning"),
5225 _string_symbol_task(is_alive, process_strings, process_symbols),
5226 _code_cache_task(num_workers, is_alive, unloading_occurred),
5227 _klass_cleaning_task(is_alive) {
5228 }
5229
5230 void pre_work_verification() {
5231 // The VM Thread will have registered Metadata during the single-threaded phase of MetadataStackOnMark.
5232 assert(Thread::current()->is_VM_thread()
5233 || !MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5234 }
5235
5236 void post_work_verification() {
5237 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5238 }
5239
5240 // The parallel work done by all worker threads.
5241 void work(uint worker_id) {
5242 pre_work_verification();
5243
5244 // Do first pass of code cache cleaning.
5245 _code_cache_task.work_first_pass(worker_id);
5246
5247 // Let the threads mark that the first pass is done.
5248 _code_cache_task.barrier_mark(worker_id);
5249
5250 // Clean the Strings and Symbols.
5251 _string_symbol_task.work(worker_id);
5252
5253 // Wait for all workers to finish the first code cache cleaning pass.
5254 _code_cache_task.barrier_wait(worker_id);
5255
5256 // Do the second code cache cleaning work, which realize on
5257 // the liveness information gathered during the first pass.
5258 _code_cache_task.work_second_pass(worker_id);
5259
5260 // Clean all klasses that were not unloaded.
5261 _klass_cleaning_task.work();
5262
5263 post_work_verification();
5264 }
5265 };
5266
5267
5268 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5269 bool process_strings,
5270 bool process_symbols,
5271 bool class_unloading_occurred) {
5272 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5273 workers()->active_workers() : 1);
5274
5275 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5276 n_workers, class_unloading_occurred);
5277 if (G1CollectedHeap::use_parallel_gc_threads()) {
5278 set_par_threads(n_workers);
5279 workers()->run_task(&g1_unlink_task);
5280 set_par_threads(0);
5281 } else {
5282 g1_unlink_task.work(0);
5283 }
5284 }
5285
5286 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5287 bool process_strings, bool process_symbols) {
5288 {
5289 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5290 _g1h->workers()->active_workers() : 1);
5291 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5292 if (G1CollectedHeap::use_parallel_gc_threads()) {
5293 set_par_threads(n_workers);
5294 workers()->run_task(&g1_unlink_task);
5295 set_par_threads(0);
5296 } else {
5297 g1_unlink_task.work(0);
5298 }
5299 }
5300
5301 if (G1StringDedup::is_enabled()) {
5302 G1StringDedup::unlink(is_alive);
5303 }
5304 }
5305
5306 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5307 private:
5308 DirtyCardQueueSet* _queue;
5309 public:
5310 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5311
5312 virtual void work(uint worker_id) {
5313 double start_time = os::elapsedTime();
5314
5315 RedirtyLoggedCardTableEntryClosure cl;
5316 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5317 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5318 } else {
5319 _queue->apply_closure_to_all_completed_buffers(&cl);
5320 }
5321
5322 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5323 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5324 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5325 }
5326 };
5327
5328 void G1CollectedHeap::redirty_logged_cards() {
5329 double redirty_logged_cards_start = os::elapsedTime();
5330
5331 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5332 _g1h->workers()->active_workers() : 1);
5333
5334 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5335 dirty_card_queue_set().reset_for_par_iteration();
5336 if (use_parallel_gc_threads()) {
5337 set_par_threads(n_workers);
5338 workers()->run_task(&redirty_task);
5339 set_par_threads(0);
5340 } else {
5341 redirty_task.work(0);
5342 }
5343
5344 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5345 dcq.merge_bufferlists(&dirty_card_queue_set());
5346 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5347
5348 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5349 }
5350
5351 // Weak Reference Processing support
5352
5353 // An always "is_alive" closure that is used to preserve referents.
5354 // If the object is non-null then it's alive. Used in the preservation
5355 // of referent objects that are pointed to by reference objects
5356 // discovered by the CM ref processor.
5357 class G1AlwaysAliveClosure: public BoolObjectClosure {
5358 G1CollectedHeap* _g1;
5359 public:
5360 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5361 bool do_object_b(oop p) {
5362 if (p != NULL) {
5363 return true;
5364 }
5365 return false;
5366 }
5367 };
5368
5369 bool G1STWIsAliveClosure::do_object_b(oop p) {
5370 // An object is reachable if it is outside the collection set,
5371 // or is inside and copied.
5372 return !_g1->obj_in_cs(p) || p->is_forwarded();
5373 }
5374
5375 // Non Copying Keep Alive closure
5376 class G1KeepAliveClosure: public OopClosure {
5377 G1CollectedHeap* _g1;
5378 public:
5379 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5380 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5381 void do_oop(oop* p) {
5382 oop obj = *p;
5383 assert(obj != NULL, "the caller should have filtered out NULL values");
5384
5385 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5386 if (cset_state == G1CollectedHeap::InNeither) {
5387 return;
5388 }
5389 if (cset_state == G1CollectedHeap::InCSet) {
5390 assert( obj->is_forwarded(), "invariant" );
5391 *p = obj->forwardee();
5392 } else {
5393 assert(!obj->is_forwarded(), "invariant" );
5394 assert(cset_state == G1CollectedHeap::IsHumongous,
5395 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5396 _g1->set_humongous_is_live(obj);
5397 }
5398 }
5399 };
5400
5401 // Copying Keep Alive closure - can be called from both
5402 // serial and parallel code as long as different worker
5403 // threads utilize different G1ParScanThreadState instances
5404 // and different queues.
5405
5406 class G1CopyingKeepAliveClosure: public OopClosure {
5407 G1CollectedHeap* _g1h;
5408 OopClosure* _copy_non_heap_obj_cl;
5409 G1ParScanThreadState* _par_scan_state;
5410
5411 public:
5412 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5413 OopClosure* non_heap_obj_cl,
5414 G1ParScanThreadState* pss):
5415 _g1h(g1h),
5416 _copy_non_heap_obj_cl(non_heap_obj_cl),
5417 _par_scan_state(pss)
5418 {}
5419
5420 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5421 virtual void do_oop( oop* p) { do_oop_work(p); }
5422
5423 template <class T> void do_oop_work(T* p) {
5424 oop obj = oopDesc::load_decode_heap_oop(p);
5425
5426 if (_g1h->is_in_cset_or_humongous(obj)) {
5427 // If the referent object has been forwarded (either copied
5428 // to a new location or to itself in the event of an
5429 // evacuation failure) then we need to update the reference
5430 // field and, if both reference and referent are in the G1
5431 // heap, update the RSet for the referent.
5432 //
5433 // If the referent has not been forwarded then we have to keep
5434 // it alive by policy. Therefore we have copy the referent.
5435 //
5436 // If the reference field is in the G1 heap then we can push
5437 // on the PSS queue. When the queue is drained (after each
5438 // phase of reference processing) the object and it's followers
5439 // will be copied, the reference field set to point to the
5440 // new location, and the RSet updated. Otherwise we need to
5441 // use the the non-heap or metadata closures directly to copy
5442 // the referent object and update the pointer, while avoiding
5443 // updating the RSet.
5444
5445 if (_g1h->is_in_g1_reserved(p)) {
5446 _par_scan_state->push_on_queue(p);
5447 } else {
5448 assert(!Metaspace::contains((const void*)p),
5449 err_msg("Unexpectedly found a pointer from metadata: "
5450 PTR_FORMAT, p));
5451 _copy_non_heap_obj_cl->do_oop(p);
5452 }
5453 }
5454 }
5455 };
5456
5457 // Serial drain queue closure. Called as the 'complete_gc'
5458 // closure for each discovered list in some of the
5459 // reference processing phases.
5460
5461 class G1STWDrainQueueClosure: public VoidClosure {
5462 protected:
5463 G1CollectedHeap* _g1h;
5464 G1ParScanThreadState* _par_scan_state;
5465
5466 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5467
5468 public:
5469 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5470 _g1h(g1h),
5471 _par_scan_state(pss)
5472 { }
5473
5474 void do_void() {
5475 G1ParScanThreadState* const pss = par_scan_state();
5476 pss->trim_queue();
5477 }
5478 };
5479
5480 // Parallel Reference Processing closures
5481
5482 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5483 // processing during G1 evacuation pauses.
5484
5485 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5486 private:
5487 G1CollectedHeap* _g1h;
5488 RefToScanQueueSet* _queues;
5489 FlexibleWorkGang* _workers;
5490 int _active_workers;
5491
5492 public:
5493 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5494 FlexibleWorkGang* workers,
5495 RefToScanQueueSet *task_queues,
5496 int n_workers) :
5497 _g1h(g1h),
5498 _queues(task_queues),
5499 _workers(workers),
5500 _active_workers(n_workers)
5501 {
5502 assert(n_workers > 0, "shouldn't call this otherwise");
5503 }
5504
5505 // Executes the given task using concurrent marking worker threads.
5506 virtual void execute(ProcessTask& task);
5507 virtual void execute(EnqueueTask& task);
5508 };
5509
5510 // Gang task for possibly parallel reference processing
5511
5512 class G1STWRefProcTaskProxy: public AbstractGangTask {
5513 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5514 ProcessTask& _proc_task;
5515 G1CollectedHeap* _g1h;
5516 RefToScanQueueSet *_task_queues;
5517 ParallelTaskTerminator* _terminator;
5518
5519 public:
5520 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5521 G1CollectedHeap* g1h,
5522 RefToScanQueueSet *task_queues,
5523 ParallelTaskTerminator* terminator) :
5524 AbstractGangTask("Process reference objects in parallel"),
5525 _proc_task(proc_task),
5526 _g1h(g1h),
5527 _task_queues(task_queues),
5528 _terminator(terminator)
5529 {}
5530
5531 virtual void work(uint worker_id) {
5532 // The reference processing task executed by a single worker.
5533 ResourceMark rm;
5534 HandleMark hm;
5535
5536 G1STWIsAliveClosure is_alive(_g1h);
5537
5538 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5539 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5540
5541 pss.set_evac_failure_closure(&evac_failure_cl);
5542
5543 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5544
5545 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5546
5547 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5548
5549 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5550 // We also need to mark copied objects.
5551 copy_non_heap_cl = ©_mark_non_heap_cl;
5552 }
5553
5554 // Keep alive closure.
5555 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5556
5557 // Complete GC closure
5558 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5559
5560 // Call the reference processing task's work routine.
5561 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5562
5563 // Note we cannot assert that the refs array is empty here as not all
5564 // of the processing tasks (specifically phase2 - pp2_work) execute
5565 // the complete_gc closure (which ordinarily would drain the queue) so
5566 // the queue may not be empty.
5567 }
5568 };
5569
5570 // Driver routine for parallel reference processing.
5571 // Creates an instance of the ref processing gang
5572 // task and has the worker threads execute it.
5573 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5574 assert(_workers != NULL, "Need parallel worker threads.");
5575
5576 ParallelTaskTerminator terminator(_active_workers, _queues);
5577 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5578
5579 _g1h->set_par_threads(_active_workers);
5580 _workers->run_task(&proc_task_proxy);
5581 _g1h->set_par_threads(0);
5582 }
5583
5584 // Gang task for parallel reference enqueueing.
5585
5586 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5587 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5588 EnqueueTask& _enq_task;
5589
5590 public:
5591 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5592 AbstractGangTask("Enqueue reference objects in parallel"),
5593 _enq_task(enq_task)
5594 { }
5595
5596 virtual void work(uint worker_id) {
5597 _enq_task.work(worker_id);
5598 }
5599 };
5600
5601 // Driver routine for parallel reference enqueueing.
5602 // Creates an instance of the ref enqueueing gang
5603 // task and has the worker threads execute it.
5604
5605 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5606 assert(_workers != NULL, "Need parallel worker threads.");
5607
5608 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5609
5610 _g1h->set_par_threads(_active_workers);
5611 _workers->run_task(&enq_task_proxy);
5612 _g1h->set_par_threads(0);
5613 }
5614
5615 // End of weak reference support closures
5616
5617 // Abstract task used to preserve (i.e. copy) any referent objects
5618 // that are in the collection set and are pointed to by reference
5619 // objects discovered by the CM ref processor.
5620
5621 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5622 protected:
5623 G1CollectedHeap* _g1h;
5624 RefToScanQueueSet *_queues;
5625 ParallelTaskTerminator _terminator;
5626 uint _n_workers;
5627
5628 public:
5629 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5630 AbstractGangTask("ParPreserveCMReferents"),
5631 _g1h(g1h),
5632 _queues(task_queues),
5633 _terminator(workers, _queues),
5634 _n_workers(workers)
5635 { }
5636
5637 void work(uint worker_id) {
5638 ResourceMark rm;
5639 HandleMark hm;
5640
5641 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5642 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5643
5644 pss.set_evac_failure_closure(&evac_failure_cl);
5645
5646 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5647
5648 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5649
5650 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5651
5652 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5653
5654 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5655 // We also need to mark copied objects.
5656 copy_non_heap_cl = ©_mark_non_heap_cl;
5657 }
5658
5659 // Is alive closure
5660 G1AlwaysAliveClosure always_alive(_g1h);
5661
5662 // Copying keep alive closure. Applied to referent objects that need
5663 // to be copied.
5664 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5665
5666 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5667
5668 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5669 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5670
5671 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5672 // So this must be true - but assert just in case someone decides to
5673 // change the worker ids.
5674 assert(0 <= worker_id && worker_id < limit, "sanity");
5675 assert(!rp->discovery_is_atomic(), "check this code");
5676
5677 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5678 for (uint idx = worker_id; idx < limit; idx += stride) {
5679 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5680
5681 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5682 while (iter.has_next()) {
5683 // Since discovery is not atomic for the CM ref processor, we
5684 // can see some null referent objects.
5685 iter.load_ptrs(DEBUG_ONLY(true));
5686 oop ref = iter.obj();
5687
5688 // This will filter nulls.
5689 if (iter.is_referent_alive()) {
5690 iter.make_referent_alive();
5691 }
5692 iter.move_to_next();
5693 }
5694 }
5695
5696 // Drain the queue - which may cause stealing
5697 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5698 drain_queue.do_void();
5699 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5700 assert(pss.queue_is_empty(), "should be");
5701 }
5702 };
5703
5704 // Weak Reference processing during an evacuation pause (part 1).
5705 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5706 double ref_proc_start = os::elapsedTime();
5707
5708 ReferenceProcessor* rp = _ref_processor_stw;
5709 assert(rp->discovery_enabled(), "should have been enabled");
5710
5711 // Any reference objects, in the collection set, that were 'discovered'
5712 // by the CM ref processor should have already been copied (either by
5713 // applying the external root copy closure to the discovered lists, or
5714 // by following an RSet entry).
5715 //
5716 // But some of the referents, that are in the collection set, that these
5717 // reference objects point to may not have been copied: the STW ref
5718 // processor would have seen that the reference object had already
5719 // been 'discovered' and would have skipped discovering the reference,
5720 // but would not have treated the reference object as a regular oop.
5721 // As a result the copy closure would not have been applied to the
5722 // referent object.
5723 //
5724 // We need to explicitly copy these referent objects - the references
5725 // will be processed at the end of remarking.
5726 //
5727 // We also need to do this copying before we process the reference
5728 // objects discovered by the STW ref processor in case one of these
5729 // referents points to another object which is also referenced by an
5730 // object discovered by the STW ref processor.
5731
5732 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5733 no_of_gc_workers == workers()->active_workers(),
5734 "Need to reset active GC workers");
5735
5736 set_par_threads(no_of_gc_workers);
5737 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5738 no_of_gc_workers,
5739 _task_queues);
5740
5741 if (G1CollectedHeap::use_parallel_gc_threads()) {
5742 workers()->run_task(&keep_cm_referents);
5743 } else {
5744 keep_cm_referents.work(0);
5745 }
5746
5747 set_par_threads(0);
5748
5749 // Closure to test whether a referent is alive.
5750 G1STWIsAliveClosure is_alive(this);
5751
5752 // Even when parallel reference processing is enabled, the processing
5753 // of JNI refs is serial and performed serially by the current thread
5754 // rather than by a worker. The following PSS will be used for processing
5755 // JNI refs.
5756
5757 // Use only a single queue for this PSS.
5758 G1ParScanThreadState pss(this, 0, NULL);
5759
5760 // We do not embed a reference processor in the copying/scanning
5761 // closures while we're actually processing the discovered
5762 // reference objects.
5763 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5764
5765 pss.set_evac_failure_closure(&evac_failure_cl);
5766
5767 assert(pss.queue_is_empty(), "pre-condition");
5768
5769 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5770
5771 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5772
5773 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5774
5775 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5776 // We also need to mark copied objects.
5777 copy_non_heap_cl = ©_mark_non_heap_cl;
5778 }
5779
5780 // Keep alive closure.
5781 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5782
5783 // Serial Complete GC closure
5784 G1STWDrainQueueClosure drain_queue(this, &pss);
5785
5786 // Setup the soft refs policy...
5787 rp->setup_policy(false);
5788
5789 ReferenceProcessorStats stats;
5790 if (!rp->processing_is_mt()) {
5791 // Serial reference processing...
5792 stats = rp->process_discovered_references(&is_alive,
5793 &keep_alive,
5794 &drain_queue,
5795 NULL,
5796 _gc_timer_stw,
5797 _gc_tracer_stw->gc_id());
5798 } else {
5799 // Parallel reference processing
5800 assert(rp->num_q() == no_of_gc_workers, "sanity");
5801 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5802
5803 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5804 stats = rp->process_discovered_references(&is_alive,
5805 &keep_alive,
5806 &drain_queue,
5807 &par_task_executor,
5808 _gc_timer_stw,
5809 _gc_tracer_stw->gc_id());
5810 }
5811
5812 _gc_tracer_stw->report_gc_reference_stats(stats);
5813
5814 // We have completed copying any necessary live referent objects.
5815 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5816
5817 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5818 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5819 }
5820
5821 // Weak Reference processing during an evacuation pause (part 2).
5822 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5823 double ref_enq_start = os::elapsedTime();
5824
5825 ReferenceProcessor* rp = _ref_processor_stw;
5826 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5827
5828 // Now enqueue any remaining on the discovered lists on to
5829 // the pending list.
5830 if (!rp->processing_is_mt()) {
5831 // Serial reference processing...
5832 rp->enqueue_discovered_references();
5833 } else {
5834 // Parallel reference enqueueing
5835
5836 assert(no_of_gc_workers == workers()->active_workers(),
5837 "Need to reset active workers");
5838 assert(rp->num_q() == no_of_gc_workers, "sanity");
5839 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5840
5841 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5842 rp->enqueue_discovered_references(&par_task_executor);
5843 }
5844
5845 rp->verify_no_references_recorded();
5846 assert(!rp->discovery_enabled(), "should have been disabled");
5847
5848 // FIXME
5849 // CM's reference processing also cleans up the string and symbol tables.
5850 // Should we do that here also? We could, but it is a serial operation
5851 // and could significantly increase the pause time.
5852
5853 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5854 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5855 }
5856
5857 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5858 _expand_heap_after_alloc_failure = true;
5859 _evacuation_failed = false;
5860
5861 // Should G1EvacuationFailureALot be in effect for this GC?
5862 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5863
5864 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5865
5866 // Disable the hot card cache.
5867 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5868 hot_card_cache->reset_hot_cache_claimed_index();
5869 hot_card_cache->set_use_cache(false);
5870
5871 uint n_workers;
5872 if (G1CollectedHeap::use_parallel_gc_threads()) {
5873 n_workers =
5874 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5875 workers()->active_workers(),
5876 Threads::number_of_non_daemon_threads());
5877 assert(UseDynamicNumberOfGCThreads ||
5878 n_workers == workers()->total_workers(),
5879 "If not dynamic should be using all the workers");
5880 workers()->set_active_workers(n_workers);
5881 set_par_threads(n_workers);
5882 } else {
5883 assert(n_par_threads() == 0,
5884 "Should be the original non-parallel value");
5885 n_workers = 1;
5886 }
5887
5888 G1ParTask g1_par_task(this, _task_queues);
5889
5890 init_for_evac_failure(NULL);
5891
5892 rem_set()->prepare_for_younger_refs_iterate(true);
5893
5894 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5895 double start_par_time_sec = os::elapsedTime();
5896 double end_par_time_sec;
5897
5898 {
5899 StrongRootsScope srs(this);
5900 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5901 if (g1_policy()->during_initial_mark_pause()) {
5902 ClassLoaderDataGraph::clear_claimed_marks();
5903 }
5904
5905 if (G1CollectedHeap::use_parallel_gc_threads()) {
5906 // The individual threads will set their evac-failure closures.
5907 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5908 // These tasks use ShareHeap::_process_strong_tasks
5909 assert(UseDynamicNumberOfGCThreads ||
5910 workers()->active_workers() == workers()->total_workers(),
5911 "If not dynamic should be using all the workers");
5912 workers()->run_task(&g1_par_task);
5913 } else {
5914 g1_par_task.set_for_termination(n_workers);
5915 g1_par_task.work(0);
5916 }
5917 end_par_time_sec = os::elapsedTime();
5918
5919 // Closing the inner scope will execute the destructor
5920 // for the StrongRootsScope object. We record the current
5921 // elapsed time before closing the scope so that time
5922 // taken for the SRS destructor is NOT included in the
5923 // reported parallel time.
5924 }
5925
5926 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5927 g1_policy()->phase_times()->record_par_time(par_time_ms);
5928
5929 double code_root_fixup_time_ms =
5930 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5931 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5932
5933 set_par_threads(0);
5934
5935 // Process any discovered reference objects - we have
5936 // to do this _before_ we retire the GC alloc regions
5937 // as we may have to copy some 'reachable' referent
5938 // objects (and their reachable sub-graphs) that were
5939 // not copied during the pause.
5940 process_discovered_references(n_workers);
5941
5942 // Weak root processing.
5943 {
5944 G1STWIsAliveClosure is_alive(this);
5945 G1KeepAliveClosure keep_alive(this);
5946 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5947 if (G1StringDedup::is_enabled()) {
5948 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5949 }
5950 }
5951
5952 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5953 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5954
5955 // Reset and re-enable the hot card cache.
5956 // Note the counts for the cards in the regions in the
5957 // collection set are reset when the collection set is freed.
5958 hot_card_cache->reset_hot_cache();
5959 hot_card_cache->set_use_cache(true);
5960
5961 purge_code_root_memory();
5962
5963 if (g1_policy()->during_initial_mark_pause()) {
5964 // Reset the claim values set during marking the strong code roots
5965 reset_heap_region_claim_values();
5966 }
5967
5968 finalize_for_evac_failure();
5969
5970 if (evacuation_failed()) {
5971 remove_self_forwarding_pointers();
5972
5973 // Reset the G1EvacuationFailureALot counters and flags
5974 // Note: the values are reset only when an actual
5975 // evacuation failure occurs.
5976 NOT_PRODUCT(reset_evacuation_should_fail();)
5977 }
5978
5979 // Enqueue any remaining references remaining on the STW
5980 // reference processor's discovered lists. We need to do
5981 // this after the card table is cleaned (and verified) as
5982 // the act of enqueueing entries on to the pending list
5983 // will log these updates (and dirty their associated
5984 // cards). We need these updates logged to update any
5985 // RSets.
5986 enqueue_discovered_references(n_workers);
5987
5988 redirty_logged_cards();
5989 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5990 }
5991
5992 void G1CollectedHeap::free_region(HeapRegion* hr,
5993 FreeRegionList* free_list,
5994 bool par,
5995 bool locked) {
5996 assert(!hr->is_free(), "the region should not be free");
5997 assert(!hr->is_empty(), "the region should not be empty");
5998 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5999 assert(free_list != NULL, "pre-condition");
6000
6001 if (G1VerifyBitmaps) {
6002 MemRegion mr(hr->bottom(), hr->end());
6003 concurrent_mark()->clearRangePrevBitmap(mr);
6004 }
6005
6006 // Clear the card counts for this region.
6007 // Note: we only need to do this if the region is not young
6008 // (since we don't refine cards in young regions).
6009 if (!hr->is_young()) {
6010 _cg1r->hot_card_cache()->reset_card_counts(hr);
6011 }
6012 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
6013 free_list->add_ordered(hr);
6014 }
6015
6016 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
6017 FreeRegionList* free_list,
6018 bool par) {
6019 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6020 assert(free_list != NULL, "pre-condition");
6021
6022 size_t hr_capacity = hr->capacity();
6023 // We need to read this before we make the region non-humongous,
6024 // otherwise the information will be gone.
6025 uint last_index = hr->last_hc_index();
6026 hr->clear_humongous();
6027 free_region(hr, free_list, par);
6028
6029 uint i = hr->hrm_index() + 1;
6030 while (i < last_index) {
6031 HeapRegion* curr_hr = region_at(i);
6032 assert(curr_hr->continuesHumongous(), "invariant");
6033 curr_hr->clear_humongous();
6034 free_region(curr_hr, free_list, par);
6035 i += 1;
6036 }
6037 }
6038
6039 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6040 const HeapRegionSetCount& humongous_regions_removed) {
6041 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6042 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6043 _old_set.bulk_remove(old_regions_removed);
6044 _humongous_set.bulk_remove(humongous_regions_removed);
6045 }
6046
6047 }
6048
6049 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6050 assert(list != NULL, "list can't be null");
6051 if (!list->is_empty()) {
6052 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6053 _hrm.insert_list_into_free_list(list);
6054 }
6055 }
6056
6057 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6058 _allocator->decrease_used(bytes);
6059 }
6060
6061 class G1ParCleanupCTTask : public AbstractGangTask {
6062 G1SATBCardTableModRefBS* _ct_bs;
6063 G1CollectedHeap* _g1h;
6064 HeapRegion* volatile _su_head;
6065 public:
6066 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6067 G1CollectedHeap* g1h) :
6068 AbstractGangTask("G1 Par Cleanup CT Task"),
6069 _ct_bs(ct_bs), _g1h(g1h) { }
6070
6071 void work(uint worker_id) {
6072 HeapRegion* r;
6073 while (r = _g1h->pop_dirty_cards_region()) {
6074 clear_cards(r);
6075 }
6076 }
6077
6078 void clear_cards(HeapRegion* r) {
6079 // Cards of the survivors should have already been dirtied.
6080 if (!r->is_survivor()) {
6081 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6082 }
6083 }
6084 };
6085
6086 #ifndef PRODUCT
6087 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6088 G1CollectedHeap* _g1h;
6089 G1SATBCardTableModRefBS* _ct_bs;
6090 public:
6091 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6092 : _g1h(g1h), _ct_bs(ct_bs) { }
6093 virtual bool doHeapRegion(HeapRegion* r) {
6094 if (r->is_survivor()) {
6095 _g1h->verify_dirty_region(r);
6096 } else {
6097 _g1h->verify_not_dirty_region(r);
6098 }
6099 return false;
6100 }
6101 };
6102
6103 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6104 // All of the region should be clean.
6105 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6106 MemRegion mr(hr->bottom(), hr->end());
6107 ct_bs->verify_not_dirty_region(mr);
6108 }
6109
6110 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6111 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6112 // dirty allocated blocks as they allocate them. The thread that
6113 // retires each region and replaces it with a new one will do a
6114 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6115 // not dirty that area (one less thing to have to do while holding
6116 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6117 // is dirty.
6118 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6119 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6120 if (hr->is_young()) {
6121 ct_bs->verify_g1_young_region(mr);
6122 } else {
6123 ct_bs->verify_dirty_region(mr);
6124 }
6125 }
6126
6127 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6128 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6129 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6130 verify_dirty_region(hr);
6131 }
6132 }
6133
6134 void G1CollectedHeap::verify_dirty_young_regions() {
6135 verify_dirty_young_list(_young_list->first_region());
6136 }
6137
6138 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6139 HeapWord* tams, HeapWord* end) {
6140 guarantee(tams <= end,
6141 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6142 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6143 if (result < end) {
6144 gclog_or_tty->cr();
6145 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6146 bitmap_name, result);
6147 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6148 bitmap_name, tams, end);
6149 return false;
6150 }
6151 return true;
6152 }
6153
6154 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6155 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6156 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6157
6158 HeapWord* bottom = hr->bottom();
6159 HeapWord* ptams = hr->prev_top_at_mark_start();
6160 HeapWord* ntams = hr->next_top_at_mark_start();
6161 HeapWord* end = hr->end();
6162
6163 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6164
6165 bool res_n = true;
6166 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6167 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6168 // if we happen to be in that state.
6169 if (mark_in_progress() || !_cmThread->in_progress()) {
6170 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6171 }
6172 if (!res_p || !res_n) {
6173 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6174 HR_FORMAT_PARAMS(hr));
6175 gclog_or_tty->print_cr("#### Caller: %s", caller);
6176 return false;
6177 }
6178 return true;
6179 }
6180
6181 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6182 if (!G1VerifyBitmaps) return;
6183
6184 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6185 }
6186
6187 class G1VerifyBitmapClosure : public HeapRegionClosure {
6188 private:
6189 const char* _caller;
6190 G1CollectedHeap* _g1h;
6191 bool _failures;
6192
6193 public:
6194 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6195 _caller(caller), _g1h(g1h), _failures(false) { }
6196
6197 bool failures() { return _failures; }
6198
6199 virtual bool doHeapRegion(HeapRegion* hr) {
6200 if (hr->continuesHumongous()) return false;
6201
6202 bool result = _g1h->verify_bitmaps(_caller, hr);
6203 if (!result) {
6204 _failures = true;
6205 }
6206 return false;
6207 }
6208 };
6209
6210 void G1CollectedHeap::check_bitmaps(const char* caller) {
6211 if (!G1VerifyBitmaps) return;
6212
6213 G1VerifyBitmapClosure cl(caller, this);
6214 heap_region_iterate(&cl);
6215 guarantee(!cl.failures(), "bitmap verification");
6216 }
6217 #endif // PRODUCT
6218
6219 void G1CollectedHeap::cleanUpCardTable() {
6220 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6221 double start = os::elapsedTime();
6222
6223 {
6224 // Iterate over the dirty cards region list.
6225 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6226
6227 if (G1CollectedHeap::use_parallel_gc_threads()) {
6228 set_par_threads();
6229 workers()->run_task(&cleanup_task);
6230 set_par_threads(0);
6231 } else {
6232 while (_dirty_cards_region_list) {
6233 HeapRegion* r = _dirty_cards_region_list;
6234 cleanup_task.clear_cards(r);
6235 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6236 if (_dirty_cards_region_list == r) {
6237 // The last region.
6238 _dirty_cards_region_list = NULL;
6239 }
6240 r->set_next_dirty_cards_region(NULL);
6241 }
6242 }
6243 #ifndef PRODUCT
6244 if (G1VerifyCTCleanup || VerifyAfterGC) {
6245 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6246 heap_region_iterate(&cleanup_verifier);
6247 }
6248 #endif
6249 }
6250
6251 double elapsed = os::elapsedTime() - start;
6252 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6253 }
6254
6255 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6256 size_t pre_used = 0;
6257 FreeRegionList local_free_list("Local List for CSet Freeing");
6258
6259 double young_time_ms = 0.0;
6260 double non_young_time_ms = 0.0;
6261
6262 // Since the collection set is a superset of the the young list,
6263 // all we need to do to clear the young list is clear its
6264 // head and length, and unlink any young regions in the code below
6265 _young_list->clear();
6266
6267 G1CollectorPolicy* policy = g1_policy();
6268
6269 double start_sec = os::elapsedTime();
6270 bool non_young = true;
6271
6272 HeapRegion* cur = cs_head;
6273 int age_bound = -1;
6274 size_t rs_lengths = 0;
6275
6276 while (cur != NULL) {
6277 assert(!is_on_master_free_list(cur), "sanity");
6278 if (non_young) {
6279 if (cur->is_young()) {
6280 double end_sec = os::elapsedTime();
6281 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6282 non_young_time_ms += elapsed_ms;
6283
6284 start_sec = os::elapsedTime();
6285 non_young = false;
6286 }
6287 } else {
6288 if (!cur->is_young()) {
6289 double end_sec = os::elapsedTime();
6290 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6291 young_time_ms += elapsed_ms;
6292
6293 start_sec = os::elapsedTime();
6294 non_young = true;
6295 }
6296 }
6297
6298 rs_lengths += cur->rem_set()->occupied_locked();
6299
6300 HeapRegion* next = cur->next_in_collection_set();
6301 assert(cur->in_collection_set(), "bad CS");
6302 cur->set_next_in_collection_set(NULL);
6303 cur->set_in_collection_set(false);
6304
6305 if (cur->is_young()) {
6306 int index = cur->young_index_in_cset();
6307 assert(index != -1, "invariant");
6308 assert((uint) index < policy->young_cset_region_length(), "invariant");
6309 size_t words_survived = _surviving_young_words[index];
6310 cur->record_surv_words_in_group(words_survived);
6311
6312 // At this point the we have 'popped' cur from the collection set
6313 // (linked via next_in_collection_set()) but it is still in the
6314 // young list (linked via next_young_region()). Clear the
6315 // _next_young_region field.
6316 cur->set_next_young_region(NULL);
6317 } else {
6318 int index = cur->young_index_in_cset();
6319 assert(index == -1, "invariant");
6320 }
6321
6322 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6323 (!cur->is_young() && cur->young_index_in_cset() == -1),
6324 "invariant" );
6325
6326 if (!cur->evacuation_failed()) {
6327 MemRegion used_mr = cur->used_region();
6328
6329 // And the region is empty.
6330 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6331 pre_used += cur->used();
6332 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6333 } else {
6334 cur->uninstall_surv_rate_group();
6335 if (cur->is_young()) {
6336 cur->set_young_index_in_cset(-1);
6337 }
6338 cur->set_evacuation_failed(false);
6339 // The region is now considered to be old.
6340 cur->set_old();
6341 _old_set.add(cur);
6342 evacuation_info.increment_collectionset_used_after(cur->used());
6343 }
6344 cur = next;
6345 }
6346
6347 evacuation_info.set_regions_freed(local_free_list.length());
6348 policy->record_max_rs_lengths(rs_lengths);
6349 policy->cset_regions_freed();
6350
6351 double end_sec = os::elapsedTime();
6352 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6353
6354 if (non_young) {
6355 non_young_time_ms += elapsed_ms;
6356 } else {
6357 young_time_ms += elapsed_ms;
6358 }
6359
6360 prepend_to_freelist(&local_free_list);
6361 decrement_summary_bytes(pre_used);
6362 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6363 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6364 }
6365
6366 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6367 private:
6368 FreeRegionList* _free_region_list;
6369 HeapRegionSet* _proxy_set;
6370 HeapRegionSetCount _humongous_regions_removed;
6371 size_t _freed_bytes;
6372 public:
6373
6374 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6375 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6376 }
6377
6378 virtual bool doHeapRegion(HeapRegion* r) {
6379 if (!r->startsHumongous()) {
6380 return false;
6381 }
6382
6383 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6384
6385 oop obj = (oop)r->bottom();
6386 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6387
6388 // The following checks whether the humongous object is live are sufficient.
6389 // The main additional check (in addition to having a reference from the roots
6390 // or the young gen) is whether the humongous object has a remembered set entry.
6391 //
6392 // A humongous object cannot be live if there is no remembered set for it
6393 // because:
6394 // - there can be no references from within humongous starts regions referencing
6395 // the object because we never allocate other objects into them.
6396 // (I.e. there are no intra-region references that may be missed by the
6397 // remembered set)
6398 // - as soon there is a remembered set entry to the humongous starts region
6399 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6400 // until the end of a concurrent mark.
6401 //
6402 // It is not required to check whether the object has been found dead by marking
6403 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6404 // all objects allocated during that time are considered live.
6405 // SATB marking is even more conservative than the remembered set.
6406 // So if at this point in the collection there is no remembered set entry,
6407 // nobody has a reference to it.
6408 // At the start of collection we flush all refinement logs, and remembered sets
6409 // are completely up-to-date wrt to references to the humongous object.
6410 //
6411 // Other implementation considerations:
6412 // - never consider object arrays: while they are a valid target, they have not
6413 // been observed to be used as temporary objects.
6414 // - they would also pose considerable effort for cleaning up the the remembered
6415 // sets.
6416 // While this cleanup is not strictly necessary to be done (or done instantly),
6417 // given that their occurrence is very low, this saves us this additional
6418 // complexity.
6419 uint region_idx = r->hrm_index();
6420 if (g1h->humongous_is_live(region_idx) ||
6421 g1h->humongous_region_is_always_live(region_idx)) {
6422
6423 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6424 gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6425 r->isHumongous(),
6426 region_idx,
6427 r->rem_set()->occupied(),
6428 r->rem_set()->strong_code_roots_list_length(),
6429 next_bitmap->isMarked(r->bottom()),
6430 g1h->humongous_is_live(region_idx),
6431 obj->is_objArray()
6432 );
6433 }
6434
6435 return false;
6436 }
6437
6438 guarantee(!obj->is_objArray(),
6439 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6440 r->bottom()));
6441
6442 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6443 gclog_or_tty->print_cr("Reclaim humongous region %d start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6444 r->isHumongous(),
6445 r->bottom(),
6446 region_idx,
6447 r->region_num(),
6448 r->rem_set()->occupied(),
6449 r->rem_set()->strong_code_roots_list_length(),
6450 next_bitmap->isMarked(r->bottom()),
6451 g1h->humongous_is_live(region_idx),
6452 obj->is_objArray()
6453 );
6454 }
6455 // Need to clear mark bit of the humongous object if already set.
6456 if (next_bitmap->isMarked(r->bottom())) {
6457 next_bitmap->clear(r->bottom());
6458 }
6459 _freed_bytes += r->used();
6460 r->set_containing_set(NULL);
6461 _humongous_regions_removed.increment(1u, r->capacity());
6462 g1h->free_humongous_region(r, _free_region_list, false);
6463
6464 return false;
6465 }
6466
6467 HeapRegionSetCount& humongous_free_count() {
6468 return _humongous_regions_removed;
6469 }
6470
6471 size_t bytes_freed() const {
6472 return _freed_bytes;
6473 }
6474
6475 size_t humongous_reclaimed() const {
6476 return _humongous_regions_removed.length();
6477 }
6478 };
6479
6480 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6481 assert_at_safepoint(true);
6482
6483 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) {
6484 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6485 return;
6486 }
6487
6488 double start_time = os::elapsedTime();
6489
6490 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6491
6492 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6493 heap_region_iterate(&cl);
6494
6495 HeapRegionSetCount empty_set;
6496 remove_from_old_sets(empty_set, cl.humongous_free_count());
6497
6498 G1HRPrinter* hr_printer = _g1h->hr_printer();
6499 if (hr_printer->is_active()) {
6500 FreeRegionListIterator iter(&local_cleanup_list);
6501 while (iter.more_available()) {
6502 HeapRegion* hr = iter.get_next();
6503 hr_printer->cleanup(hr);
6504 }
6505 }
6506
6507 prepend_to_freelist(&local_cleanup_list);
6508 decrement_summary_bytes(cl.bytes_freed());
6509
6510 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6511 cl.humongous_reclaimed());
6512 }
6513
6514 // This routine is similar to the above but does not record
6515 // any policy statistics or update free lists; we are abandoning
6516 // the current incremental collection set in preparation of a
6517 // full collection. After the full GC we will start to build up
6518 // the incremental collection set again.
6519 // This is only called when we're doing a full collection
6520 // and is immediately followed by the tearing down of the young list.
6521
6522 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6523 HeapRegion* cur = cs_head;
6524
6525 while (cur != NULL) {
6526 HeapRegion* next = cur->next_in_collection_set();
6527 assert(cur->in_collection_set(), "bad CS");
6528 cur->set_next_in_collection_set(NULL);
6529 cur->set_in_collection_set(false);
6530 cur->set_young_index_in_cset(-1);
6531 cur = next;
6532 }
6533 }
6534
6535 void G1CollectedHeap::set_free_regions_coming() {
6536 if (G1ConcRegionFreeingVerbose) {
6537 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6538 "setting free regions coming");
6539 }
6540
6541 assert(!free_regions_coming(), "pre-condition");
6542 _free_regions_coming = true;
6543 }
6544
6545 void G1CollectedHeap::reset_free_regions_coming() {
6546 assert(free_regions_coming(), "pre-condition");
6547
6548 {
6549 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6550 _free_regions_coming = false;
6551 SecondaryFreeList_lock->notify_all();
6552 }
6553
6554 if (G1ConcRegionFreeingVerbose) {
6555 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6556 "reset free regions coming");
6557 }
6558 }
6559
6560 void G1CollectedHeap::wait_while_free_regions_coming() {
6561 // Most of the time we won't have to wait, so let's do a quick test
6562 // first before we take the lock.
6563 if (!free_regions_coming()) {
6564 return;
6565 }
6566
6567 if (G1ConcRegionFreeingVerbose) {
6568 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6569 "waiting for free regions");
6570 }
6571
6572 {
6573 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6574 while (free_regions_coming()) {
6575 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6576 }
6577 }
6578
6579 if (G1ConcRegionFreeingVerbose) {
6580 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6581 "done waiting for free regions");
6582 }
6583 }
6584
6585 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6586 assert(heap_lock_held_for_gc(),
6587 "the heap lock should already be held by or for this thread");
6588 _young_list->push_region(hr);
6589 }
6590
6591 class NoYoungRegionsClosure: public HeapRegionClosure {
6592 private:
6593 bool _success;
6594 public:
6595 NoYoungRegionsClosure() : _success(true) { }
6596 bool doHeapRegion(HeapRegion* r) {
6597 if (r->is_young()) {
6598 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6599 r->bottom(), r->end());
6600 _success = false;
6601 }
6602 return false;
6603 }
6604 bool success() { return _success; }
6605 };
6606
6607 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6608 bool ret = _young_list->check_list_empty(check_sample);
6609
6610 if (check_heap) {
6611 NoYoungRegionsClosure closure;
6612 heap_region_iterate(&closure);
6613 ret = ret && closure.success();
6614 }
6615
6616 return ret;
6617 }
6618
6619 class TearDownRegionSetsClosure : public HeapRegionClosure {
6620 private:
6621 HeapRegionSet *_old_set;
6622
6623 public:
6624 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6625
6626 bool doHeapRegion(HeapRegion* r) {
6627 if (r->is_old()) {
6628 _old_set->remove(r);
6629 } else {
6630 // We ignore free regions, we'll empty the free list afterwards.
6631 // We ignore young regions, we'll empty the young list afterwards.
6632 // We ignore humongous regions, we're not tearing down the
6633 // humongous regions set.
6634 assert(r->is_free() || r->is_young() || r->isHumongous(),
6635 "it cannot be another type");
6636 }
6637 return false;
6638 }
6639
6640 ~TearDownRegionSetsClosure() {
6641 assert(_old_set->is_empty(), "post-condition");
6642 }
6643 };
6644
6645 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6646 assert_at_safepoint(true /* should_be_vm_thread */);
6647
6648 if (!free_list_only) {
6649 TearDownRegionSetsClosure cl(&_old_set);
6650 heap_region_iterate(&cl);
6651
6652 // Note that emptying the _young_list is postponed and instead done as
6653 // the first step when rebuilding the regions sets again. The reason for
6654 // this is that during a full GC string deduplication needs to know if
6655 // a collected region was young or old when the full GC was initiated.
6656 }
6657 _hrm.remove_all_free_regions();
6658 }
6659
6660 class RebuildRegionSetsClosure : public HeapRegionClosure {
6661 private:
6662 bool _free_list_only;
6663 HeapRegionSet* _old_set;
6664 HeapRegionManager* _hrm;
6665 size_t _total_used;
6666
6667 public:
6668 RebuildRegionSetsClosure(bool free_list_only,
6669 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6670 _free_list_only(free_list_only),
6671 _old_set(old_set), _hrm(hrm), _total_used(0) {
6672 assert(_hrm->num_free_regions() == 0, "pre-condition");
6673 if (!free_list_only) {
6674 assert(_old_set->is_empty(), "pre-condition");
6675 }
6676 }
6677
6678 bool doHeapRegion(HeapRegion* r) {
6679 if (r->continuesHumongous()) {
6680 return false;
6681 }
6682
6683 if (r->is_empty()) {
6684 // Add free regions to the free list
6685 r->set_free();
6686 r->set_allocation_context(AllocationContext::system());
6687 _hrm->insert_into_free_list(r);
6688 } else if (!_free_list_only) {
6689 assert(!r->is_young(), "we should not come across young regions");
6690
6691 if (r->isHumongous()) {
6692 // We ignore humongous regions, we left the humongous set unchanged
6693 } else {
6694 // Objects that were compacted would have ended up on regions
6695 // that were previously old or free.
6696 assert(r->is_free() || r->is_old(), "invariant");
6697 // We now consider them old, so register as such.
6698 r->set_old();
6699 _old_set->add(r);
6700 }
6701 _total_used += r->used();
6702 }
6703
6704 return false;
6705 }
6706
6707 size_t total_used() {
6708 return _total_used;
6709 }
6710 };
6711
6712 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6713 assert_at_safepoint(true /* should_be_vm_thread */);
6714
6715 if (!free_list_only) {
6716 _young_list->empty_list();
6717 }
6718
6719 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6720 heap_region_iterate(&cl);
6721
6722 if (!free_list_only) {
6723 _allocator->set_used(cl.total_used());
6724 }
6725 assert(_allocator->used_unlocked() == recalculate_used(),
6726 err_msg("inconsistent _allocator->used_unlocked(), "
6727 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6728 _allocator->used_unlocked(), recalculate_used()));
6729 }
6730
6731 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6732 _refine_cte_cl->set_concurrent(concurrent);
6733 }
6734
6735 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6736 HeapRegion* hr = heap_region_containing(p);
6737 return hr->is_in(p);
6738 }
6739
6740 // Methods for the mutator alloc region
6741
6742 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6743 bool force) {
6744 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6745 assert(!force || g1_policy()->can_expand_young_list(),
6746 "if force is true we should be able to expand the young list");
6747 bool young_list_full = g1_policy()->is_young_list_full();
6748 if (force || !young_list_full) {
6749 HeapRegion* new_alloc_region = new_region(word_size,
6750 false /* is_old */,
6751 false /* do_expand */);
6752 if (new_alloc_region != NULL) {
6753 set_region_short_lived_locked(new_alloc_region);
6754 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6755 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6756 return new_alloc_region;
6757 }
6758 }
6759 return NULL;
6760 }
6761
6762 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6763 size_t allocated_bytes) {
6764 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6765 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6766
6767 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6768 _allocator->increase_used(allocated_bytes);
6769 _hr_printer.retire(alloc_region);
6770 // We update the eden sizes here, when the region is retired,
6771 // instead of when it's allocated, since this is the point that its
6772 // used space has been recored in _summary_bytes_used.
6773 g1mm()->update_eden_size();
6774 }
6775
6776 void G1CollectedHeap::set_par_threads() {
6777 // Don't change the number of workers. Use the value previously set
6778 // in the workgroup.
6779 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6780 uint n_workers = workers()->active_workers();
6781 assert(UseDynamicNumberOfGCThreads ||
6782 n_workers == workers()->total_workers(),
6783 "Otherwise should be using the total number of workers");
6784 if (n_workers == 0) {
6785 assert(false, "Should have been set in prior evacuation pause.");
6786 n_workers = ParallelGCThreads;
6787 workers()->set_active_workers(n_workers);
6788 }
6789 set_par_threads(n_workers);
6790 }
6791
6792 // Methods for the GC alloc regions
6793
6794 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6795 uint count,
6796 GCAllocPurpose ap) {
6797 assert(FreeList_lock->owned_by_self(), "pre-condition");
6798
6799 if (count < g1_policy()->max_regions(ap)) {
6800 bool survivor = (ap == GCAllocForSurvived);
6801 HeapRegion* new_alloc_region = new_region(word_size,
6802 !survivor,
6803 true /* do_expand */);
6804 if (new_alloc_region != NULL) {
6805 // We really only need to do this for old regions given that we
6806 // should never scan survivors. But it doesn't hurt to do it
6807 // for survivors too.
6808 new_alloc_region->record_top_and_timestamp();
6809 if (survivor) {
6810 new_alloc_region->set_survivor();
6811 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6812 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6813 } else {
6814 new_alloc_region->set_old();
6815 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6816 check_bitmaps("Old Region Allocation", new_alloc_region);
6817 }
6818 bool during_im = g1_policy()->during_initial_mark_pause();
6819 new_alloc_region->note_start_of_copying(during_im);
6820 return new_alloc_region;
6821 } else {
6822 g1_policy()->note_alloc_region_limit_reached(ap);
6823 }
6824 }
6825 return NULL;
6826 }
6827
6828 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6829 size_t allocated_bytes,
6830 GCAllocPurpose ap) {
6831 bool during_im = g1_policy()->during_initial_mark_pause();
6832 alloc_region->note_end_of_copying(during_im);
6833 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6834 if (ap == GCAllocForSurvived) {
6835 young_list()->add_survivor_region(alloc_region);
6836 } else {
6837 _old_set.add(alloc_region);
6838 }
6839 _hr_printer.retire(alloc_region);
6840 }
6841
6842 // Heap region set verification
6843
6844 class VerifyRegionListsClosure : public HeapRegionClosure {
6845 private:
6846 HeapRegionSet* _old_set;
6847 HeapRegionSet* _humongous_set;
6848 HeapRegionManager* _hrm;
6849
6850 public:
6851 HeapRegionSetCount _old_count;
6852 HeapRegionSetCount _humongous_count;
6853 HeapRegionSetCount _free_count;
6854
6855 VerifyRegionListsClosure(HeapRegionSet* old_set,
6856 HeapRegionSet* humongous_set,
6857 HeapRegionManager* hrm) :
6858 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6859 _old_count(), _humongous_count(), _free_count(){ }
6860
6861 bool doHeapRegion(HeapRegion* hr) {
6862 if (hr->continuesHumongous()) {
6863 return false;
6864 }
6865
6866 if (hr->is_young()) {
6867 // TODO
6868 } else if (hr->startsHumongous()) {
6869 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6870 _humongous_count.increment(1u, hr->capacity());
6871 } else if (hr->is_empty()) {
6872 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6873 _free_count.increment(1u, hr->capacity());
6874 } else if (hr->is_old()) {
6875 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6876 _old_count.increment(1u, hr->capacity());
6877 } else {
6878 ShouldNotReachHere();
6879 }
6880 return false;
6881 }
6882
6883 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6884 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6885 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6886 old_set->total_capacity_bytes(), _old_count.capacity()));
6887
6888 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6889 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6890 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6891
6892 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()));
6893 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6894 free_list->total_capacity_bytes(), _free_count.capacity()));
6895 }
6896 };
6897
6898 void G1CollectedHeap::verify_region_sets() {
6899 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6900
6901 // First, check the explicit lists.
6902 _hrm.verify();
6903 {
6904 // Given that a concurrent operation might be adding regions to
6905 // the secondary free list we have to take the lock before
6906 // verifying it.
6907 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6908 _secondary_free_list.verify_list();
6909 }
6910
6911 // If a concurrent region freeing operation is in progress it will
6912 // be difficult to correctly attributed any free regions we come
6913 // across to the correct free list given that they might belong to
6914 // one of several (free_list, secondary_free_list, any local lists,
6915 // etc.). So, if that's the case we will skip the rest of the
6916 // verification operation. Alternatively, waiting for the concurrent
6917 // operation to complete will have a non-trivial effect on the GC's
6918 // operation (no concurrent operation will last longer than the
6919 // interval between two calls to verification) and it might hide
6920 // any issues that we would like to catch during testing.
6921 if (free_regions_coming()) {
6922 return;
6923 }
6924
6925 // Make sure we append the secondary_free_list on the free_list so
6926 // that all free regions we will come across can be safely
6927 // attributed to the free_list.
6928 append_secondary_free_list_if_not_empty_with_lock();
6929
6930 // Finally, make sure that the region accounting in the lists is
6931 // consistent with what we see in the heap.
6932
6933 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6934 heap_region_iterate(&cl);
6935 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6936 }
6937
6938 // Optimized nmethod scanning
6939
6940 class RegisterNMethodOopClosure: public OopClosure {
6941 G1CollectedHeap* _g1h;
6942 nmethod* _nm;
6943
6944 template <class T> void do_oop_work(T* p) {
6945 T heap_oop = oopDesc::load_heap_oop(p);
6946 if (!oopDesc::is_null(heap_oop)) {
6947 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6948 HeapRegion* hr = _g1h->heap_region_containing(obj);
6949 assert(!hr->continuesHumongous(),
6950 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6951 " starting at "HR_FORMAT,
6952 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6953
6954 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6955 hr->add_strong_code_root_locked(_nm);
6956 }
6957 }
6958
6959 public:
6960 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6961 _g1h(g1h), _nm(nm) {}
6962
6963 void do_oop(oop* p) { do_oop_work(p); }
6964 void do_oop(narrowOop* p) { do_oop_work(p); }
6965 };
6966
6967 class UnregisterNMethodOopClosure: public OopClosure {
6968 G1CollectedHeap* _g1h;
6969 nmethod* _nm;
6970
6971 template <class T> void do_oop_work(T* p) {
6972 T heap_oop = oopDesc::load_heap_oop(p);
6973 if (!oopDesc::is_null(heap_oop)) {
6974 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6975 HeapRegion* hr = _g1h->heap_region_containing(obj);
6976 assert(!hr->continuesHumongous(),
6977 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6978 " starting at "HR_FORMAT,
6979 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6980
6981 hr->remove_strong_code_root(_nm);
6982 }
6983 }
6984
6985 public:
6986 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6987 _g1h(g1h), _nm(nm) {}
6988
6989 void do_oop(oop* p) { do_oop_work(p); }
6990 void do_oop(narrowOop* p) { do_oop_work(p); }
6991 };
6992
6993 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6994 CollectedHeap::register_nmethod(nm);
6995
6996 guarantee(nm != NULL, "sanity");
6997 RegisterNMethodOopClosure reg_cl(this, nm);
6998 nm->oops_do(®_cl);
6999 }
7000
7001 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
7002 CollectedHeap::unregister_nmethod(nm);
7003
7004 guarantee(nm != NULL, "sanity");
7005 UnregisterNMethodOopClosure reg_cl(this, nm);
7006 nm->oops_do(®_cl, true);
7007 }
7008
7009 void G1CollectedHeap::purge_code_root_memory() {
7010 double purge_start = os::elapsedTime();
7011 G1CodeRootSet::purge();
7012 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
7013 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
7014 }
7015
7016 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
7017 G1CollectedHeap* _g1h;
7018
7019 public:
7020 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7021 _g1h(g1h) {}
7022
7023 void do_code_blob(CodeBlob* cb) {
7024 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7025 if (nm == NULL) {
7026 return;
7027 }
7028
7029 if (ScavengeRootsInCode) {
7030 _g1h->register_nmethod(nm);
7031 }
7032 }
7033 };
7034
7035 void G1CollectedHeap::rebuild_strong_code_roots() {
7036 RebuildStrongCodeRootClosure blob_cl(this);
7037 CodeCache::blobs_do(&blob_cl);
7038 }