1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1StringDedup.hpp"
52 #include "gc_implementation/g1/g1YCTypes.hpp"
53 #include "gc_implementation/g1/heapRegion.inline.hpp"
54 #include "gc_implementation/g1/heapRegionRemSet.hpp"
55 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
56 #include "gc_implementation/g1/vm_operations_g1.hpp"
57 #include "gc_implementation/shared/gcHeapSummary.hpp"
58 #include "gc_implementation/shared/gcTimer.hpp"
59 #include "gc_implementation/shared/gcTrace.hpp"
60 #include "gc_implementation/shared/gcTraceTime.hpp"
61 #include "gc_implementation/shared/isGCActiveMark.hpp"
62 #include "memory/allocation.hpp"
63 #include "memory/gcLocker.inline.hpp"
64 #include "memory/generationSpec.hpp"
65 #include "memory/iterator.hpp"
66 #include "memory/referenceProcessor.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/oop.pcgc.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Notes on implementation of parallelism in different tasks.
93 //
94 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism.
95 // The number of GC workers is passed to heap_region_par_iterate().
96 // It does use run_task() which sets _n_workers in the task.
97 // G1ParTask executes g1_process_roots() ->
98 // SharedHeap::process_roots() which calls eventually to
99 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
100 // SequentialSubTasksDone. SharedHeap::process_roots() also
101 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
102 //
103
104 // Local to this file.
105
106 class RefineCardTableEntryClosure: public CardTableEntryClosure {
107 bool _concurrent;
108 public:
109 RefineCardTableEntryClosure() : _concurrent(true) { }
110
111 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
112 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
113 // This path is executed by the concurrent refine or mutator threads,
114 // concurrently, and so we do not care if card_ptr contains references
115 // that point into the collection set.
116 assert(!oops_into_cset, "should be");
117
118 if (_concurrent && SuspendibleThreadSet::should_yield()) {
119 // Caller will actually yield.
120 return false;
121 }
122 // Otherwise, we finished successfully; return true.
123 return true;
124 }
125
126 void set_concurrent(bool b) { _concurrent = b; }
127 };
128
129
130 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
131 size_t _num_processed;
132 CardTableModRefBS* _ctbs;
133 int _histo[256];
134
135 public:
136 ClearLoggedCardTableEntryClosure() :
137 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
138 {
139 for (int i = 0; i < 256; i++) _histo[i] = 0;
140 }
141
142 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
143 unsigned char* ujb = (unsigned char*)card_ptr;
144 int ind = (int)(*ujb);
145 _histo[ind]++;
146
147 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
148 _num_processed++;
149
150 return true;
151 }
152
153 size_t num_processed() { return _num_processed; }
154
155 void print_histo() {
156 gclog_or_tty->print_cr("Card table value histogram:");
157 for (int i = 0; i < 256; i++) {
158 if (_histo[i] != 0) {
159 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
160 }
161 }
162 }
163 };
164
165 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
166 private:
167 size_t _num_processed;
168
169 public:
170 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
171
172 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
173 *card_ptr = CardTableModRefBS::dirty_card_val();
174 _num_processed++;
175 return true;
176 }
177
178 size_t num_processed() const { return _num_processed; }
179 };
180
181 YoungList::YoungList(G1CollectedHeap* g1h) :
182 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
183 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
184 guarantee(check_list_empty(false), "just making sure...");
185 }
186
187 void YoungList::push_region(HeapRegion *hr) {
188 assert(!hr->is_young(), "should not already be young");
189 assert(hr->get_next_young_region() == NULL, "cause it should!");
190
191 hr->set_next_young_region(_head);
192 _head = hr;
193
194 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
195 ++_length;
196 }
197
198 void YoungList::add_survivor_region(HeapRegion* hr) {
199 assert(hr->is_survivor(), "should be flagged as survivor region");
200 assert(hr->get_next_young_region() == NULL, "cause it should!");
201
202 hr->set_next_young_region(_survivor_head);
203 if (_survivor_head == NULL) {
204 _survivor_tail = hr;
205 }
206 _survivor_head = hr;
207 ++_survivor_length;
208 }
209
210 void YoungList::empty_list(HeapRegion* list) {
211 while (list != NULL) {
212 HeapRegion* next = list->get_next_young_region();
213 list->set_next_young_region(NULL);
214 list->uninstall_surv_rate_group();
215 // This is called before a Full GC and all the non-empty /
216 // non-humongous regions at the end of the Full GC will end up as
217 // old anyway.
218 list->set_old();
219 list = next;
220 }
221 }
222
223 void YoungList::empty_list() {
224 assert(check_list_well_formed(), "young list should be well formed");
225
226 empty_list(_head);
227 _head = NULL;
228 _length = 0;
229
230 empty_list(_survivor_head);
231 _survivor_head = NULL;
232 _survivor_tail = NULL;
233 _survivor_length = 0;
234
235 _last_sampled_rs_lengths = 0;
236
237 assert(check_list_empty(false), "just making sure...");
238 }
239
240 bool YoungList::check_list_well_formed() {
241 bool ret = true;
242
243 uint length = 0;
244 HeapRegion* curr = _head;
245 HeapRegion* last = NULL;
246 while (curr != NULL) {
247 if (!curr->is_young()) {
248 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
249 "incorrectly tagged (y: %d, surv: %d)",
250 curr->bottom(), curr->end(),
251 curr->is_young(), curr->is_survivor());
252 ret = false;
253 }
254 ++length;
255 last = curr;
256 curr = curr->get_next_young_region();
257 }
258 ret = ret && (length == _length);
259
260 if (!ret) {
261 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
262 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
263 length, _length);
264 }
265
266 return ret;
267 }
268
269 bool YoungList::check_list_empty(bool check_sample) {
270 bool ret = true;
271
272 if (_length != 0) {
273 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
274 _length);
275 ret = false;
276 }
277 if (check_sample && _last_sampled_rs_lengths != 0) {
278 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
279 ret = false;
280 }
281 if (_head != NULL) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
283 ret = false;
284 }
285 if (!ret) {
286 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
287 }
288
289 return ret;
290 }
291
292 void
293 YoungList::rs_length_sampling_init() {
294 _sampled_rs_lengths = 0;
295 _curr = _head;
296 }
297
298 bool
299 YoungList::rs_length_sampling_more() {
300 return _curr != NULL;
301 }
302
303 void
304 YoungList::rs_length_sampling_next() {
305 assert( _curr != NULL, "invariant" );
306 size_t rs_length = _curr->rem_set()->occupied();
307
308 _sampled_rs_lengths += rs_length;
309
310 // The current region may not yet have been added to the
311 // incremental collection set (it gets added when it is
312 // retired as the current allocation region).
313 if (_curr->in_collection_set()) {
314 // Update the collection set policy information for this region
315 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
316 }
317
318 _curr = _curr->get_next_young_region();
319 if (_curr == NULL) {
320 _last_sampled_rs_lengths = _sampled_rs_lengths;
321 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
322 }
323 }
324
325 void
326 YoungList::reset_auxilary_lists() {
327 guarantee( is_empty(), "young list should be empty" );
328 assert(check_list_well_formed(), "young list should be well formed");
329
330 // Add survivor regions to SurvRateGroup.
331 _g1h->g1_policy()->note_start_adding_survivor_regions();
332 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
333
334 int young_index_in_cset = 0;
335 for (HeapRegion* curr = _survivor_head;
336 curr != NULL;
337 curr = curr->get_next_young_region()) {
338 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
339
340 // The region is a non-empty survivor so let's add it to
341 // the incremental collection set for the next evacuation
342 // pause.
343 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
344 young_index_in_cset += 1;
345 }
346 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
347 _g1h->g1_policy()->note_stop_adding_survivor_regions();
348
349 _head = _survivor_head;
350 _length = _survivor_length;
351 if (_survivor_head != NULL) {
352 assert(_survivor_tail != NULL, "cause it shouldn't be");
353 assert(_survivor_length > 0, "invariant");
354 _survivor_tail->set_next_young_region(NULL);
355 }
356
357 // Don't clear the survivor list handles until the start of
358 // the next evacuation pause - we need it in order to re-tag
359 // the survivor regions from this evacuation pause as 'young'
360 // at the start of the next.
361
362 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
363
364 assert(check_list_well_formed(), "young list should be well formed");
365 }
366
367 void YoungList::print() {
368 HeapRegion* lists[] = {_head, _survivor_head};
369 const char* names[] = {"YOUNG", "SURVIVOR"};
370
371 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
372 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
373 HeapRegion *curr = lists[list];
374 if (curr == NULL)
375 gclog_or_tty->print_cr(" empty");
376 while (curr != NULL) {
377 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
378 HR_FORMAT_PARAMS(curr),
379 curr->prev_top_at_mark_start(),
380 curr->next_top_at_mark_start(),
381 curr->age_in_surv_rate_group_cond());
382 curr = curr->get_next_young_region();
383 }
384 }
385
386 gclog_or_tty->cr();
387 }
388
389 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
390 OtherRegionsTable::invalidate(start_idx, num_regions);
391 }
392
393 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
394 // The from card cache is not the memory that is actually committed. So we cannot
395 // take advantage of the zero_filled parameter.
396 reset_from_card_cache(start_idx, num_regions);
397 }
398
399 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
400 {
401 // Claim the right to put the region on the dirty cards region list
402 // by installing a self pointer.
403 HeapRegion* next = hr->get_next_dirty_cards_region();
404 if (next == NULL) {
405 HeapRegion* res = (HeapRegion*)
406 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
407 NULL);
408 if (res == NULL) {
409 HeapRegion* head;
410 do {
411 // Put the region to the dirty cards region list.
412 head = _dirty_cards_region_list;
413 next = (HeapRegion*)
414 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
415 if (next == head) {
416 assert(hr->get_next_dirty_cards_region() == hr,
417 "hr->get_next_dirty_cards_region() != hr");
418 if (next == NULL) {
419 // The last region in the list points to itself.
420 hr->set_next_dirty_cards_region(hr);
421 } else {
422 hr->set_next_dirty_cards_region(next);
423 }
424 }
425 } while (next != head);
426 }
427 }
428 }
429
430 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
431 {
432 HeapRegion* head;
433 HeapRegion* hr;
434 do {
435 head = _dirty_cards_region_list;
436 if (head == NULL) {
437 return NULL;
438 }
439 HeapRegion* new_head = head->get_next_dirty_cards_region();
440 if (head == new_head) {
441 // The last region.
442 new_head = NULL;
443 }
444 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
445 head);
446 } while (hr != head);
447 assert(hr != NULL, "invariant");
448 hr->set_next_dirty_cards_region(NULL);
449 return hr;
450 }
451
452 #ifdef ASSERT
453 // A region is added to the collection set as it is retired
454 // so an address p can point to a region which will be in the
455 // collection set but has not yet been retired. This method
456 // therefore is only accurate during a GC pause after all
457 // regions have been retired. It is used for debugging
458 // to check if an nmethod has references to objects that can
459 // be move during a partial collection. Though it can be
460 // inaccurate, it is sufficient for G1 because the conservative
461 // implementation of is_scavengable() for G1 will indicate that
462 // all nmethods must be scanned during a partial collection.
463 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
464 if (p == NULL) {
465 return false;
466 }
467 return heap_region_containing(p)->in_collection_set();
468 }
469 #endif
470
471 // Returns true if the reference points to an object that
472 // can move in an incremental collection.
473 bool G1CollectedHeap::is_scavengable(const void* p) {
474 HeapRegion* hr = heap_region_containing(p);
475 return !hr->is_humongous();
476 }
477
478 void G1CollectedHeap::check_ct_logs_at_safepoint() {
479 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
480 CardTableModRefBS* ct_bs = g1_barrier_set();
481
482 // Count the dirty cards at the start.
483 CountNonCleanMemRegionClosure count1(this);
484 ct_bs->mod_card_iterate(&count1);
485 int orig_count = count1.n();
486
487 // First clear the logged cards.
488 ClearLoggedCardTableEntryClosure clear;
489 dcqs.apply_closure_to_all_completed_buffers(&clear);
490 dcqs.iterate_closure_all_threads(&clear, false);
491 clear.print_histo();
492
493 // Now ensure that there's no dirty cards.
494 CountNonCleanMemRegionClosure count2(this);
495 ct_bs->mod_card_iterate(&count2);
496 if (count2.n() != 0) {
497 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
498 count2.n(), orig_count);
499 }
500 guarantee(count2.n() == 0, "Card table should be clean.");
501
502 RedirtyLoggedCardTableEntryClosure redirty;
503 dcqs.apply_closure_to_all_completed_buffers(&redirty);
504 dcqs.iterate_closure_all_threads(&redirty, false);
505 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
506 clear.num_processed(), orig_count);
507 guarantee(redirty.num_processed() == clear.num_processed(),
508 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
509 redirty.num_processed(), clear.num_processed()));
510
511 CountNonCleanMemRegionClosure count3(this);
512 ct_bs->mod_card_iterate(&count3);
513 if (count3.n() != orig_count) {
514 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
515 orig_count, count3.n());
516 guarantee(count3.n() >= orig_count, "Should have restored them all.");
517 }
518 }
519
520 // Private class members.
521
522 G1CollectedHeap* G1CollectedHeap::_g1h;
523
524 // Private methods.
525
526 HeapRegion*
527 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
529 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
530 if (!_secondary_free_list.is_empty()) {
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "secondary_free_list has %u entries",
534 _secondary_free_list.length());
535 }
536 // It looks as if there are free regions available on the
537 // secondary_free_list. Let's move them to the free_list and try
538 // again to allocate from it.
539 append_secondary_free_list();
540
541 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
542 "empty we should have moved at least one entry to the free_list");
543 HeapRegion* res = _hrm.allocate_free_region(is_old);
544 if (G1ConcRegionFreeingVerbose) {
545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
546 "allocated "HR_FORMAT" from secondary_free_list",
547 HR_FORMAT_PARAMS(res));
548 }
549 return res;
550 }
551
552 // Wait here until we get notified either when (a) there are no
553 // more free regions coming or (b) some regions have been moved on
554 // the secondary_free_list.
555 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
556 }
557
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "could not allocate from secondary_free_list");
561 }
562 return NULL;
563 }
564
565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
566 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
567 "the only time we use this to allocate a humongous region is "
568 "when we are allocating a single humongous region");
569
570 HeapRegion* res;
571 if (G1StressConcRegionFreeing) {
572 if (!_secondary_free_list.is_empty()) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "forced to look at the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list(is_old);
578 if (res != NULL) {
579 return res;
580 }
581 }
582 }
583
584 res = _hrm.allocate_free_region(is_old);
585
586 if (res == NULL) {
587 if (G1ConcRegionFreeingVerbose) {
588 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
589 "res == NULL, trying the secondary_free_list");
590 }
591 res = new_region_try_secondary_free_list(is_old);
592 }
593 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
594 // Currently, only attempts to allocate GC alloc regions set
595 // do_expand to true. So, we should only reach here during a
596 // safepoint. If this assumption changes we might have to
597 // reconsider the use of _expand_heap_after_alloc_failure.
598 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
599
600 ergo_verbose1(ErgoHeapSizing,
601 "attempt heap expansion",
602 ergo_format_reason("region allocation request failed")
603 ergo_format_byte("allocation request"),
604 word_size * HeapWordSize);
605 if (expand(word_size * HeapWordSize)) {
606 // Given that expand() succeeded in expanding the heap, and we
607 // always expand the heap by an amount aligned to the heap
608 // region size, the free list should in theory not be empty.
609 // In either case allocate_free_region() will check for NULL.
610 res = _hrm.allocate_free_region(is_old);
611 } else {
612 _expand_heap_after_alloc_failure = false;
613 }
614 }
615 return res;
616 }
617
618 HeapWord*
619 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
620 uint num_regions,
621 size_t word_size,
622 AllocationContext_t context) {
623 assert(first != G1_NO_HRM_INDEX, "pre-condition");
624 assert(is_humongous(word_size), "word_size should be humongous");
625 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
626
627 // Index of last region in the series + 1.
628 uint last = first + num_regions;
629
630 // We need to initialize the region(s) we just discovered. This is
631 // a bit tricky given that it can happen concurrently with
632 // refinement threads refining cards on these regions and
633 // potentially wanting to refine the BOT as they are scanning
634 // those cards (this can happen shortly after a cleanup; see CR
635 // 6991377). So we have to set up the region(s) carefully and in
636 // a specific order.
637
638 // The word size sum of all the regions we will allocate.
639 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
640 assert(word_size <= word_size_sum, "sanity");
641
642 // This will be the "starts humongous" region.
643 HeapRegion* first_hr = region_at(first);
644 // The header of the new object will be placed at the bottom of
645 // the first region.
646 HeapWord* new_obj = first_hr->bottom();
647 // This will be the new end of the first region in the series that
648 // should also match the end of the last region in the series.
649 HeapWord* new_end = new_obj + word_size_sum;
650 // This will be the new top of the first region that will reflect
651 // this allocation.
652 HeapWord* new_top = new_obj + word_size;
653
654 // First, we need to zero the header of the space that we will be
655 // allocating. When we update top further down, some refinement
656 // threads might try to scan the region. By zeroing the header we
657 // ensure that any thread that will try to scan the region will
658 // come across the zero klass word and bail out.
659 //
660 // NOTE: It would not have been correct to have used
661 // CollectedHeap::fill_with_object() and make the space look like
662 // an int array. The thread that is doing the allocation will
663 // later update the object header to a potentially different array
664 // type and, for a very short period of time, the klass and length
665 // fields will be inconsistent. This could cause a refinement
666 // thread to calculate the object size incorrectly.
667 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
668
669 // We will set up the first region as "starts humongous". This
670 // will also update the BOT covering all the regions to reflect
671 // that there is a single object that starts at the bottom of the
672 // first region.
673 first_hr->set_starts_humongous(new_top, new_end);
674 first_hr->set_allocation_context(context);
675 // Then, if there are any, we will set up the "continues
676 // humongous" regions.
677 HeapRegion* hr = NULL;
678 for (uint i = first + 1; i < last; ++i) {
679 hr = region_at(i);
680 hr->set_continues_humongous(first_hr);
681 hr->set_allocation_context(context);
682 }
683 // If we have "continues humongous" regions (hr != NULL), then the
684 // end of the last one should match new_end.
685 assert(hr == NULL || hr->end() == new_end, "sanity");
686
687 // Up to this point no concurrent thread would have been able to
688 // do any scanning on any region in this series. All the top
689 // fields still point to bottom, so the intersection between
690 // [bottom,top] and [card_start,card_end] will be empty. Before we
691 // update the top fields, we'll do a storestore to make sure that
692 // no thread sees the update to top before the zeroing of the
693 // object header and the BOT initialization.
694 OrderAccess::storestore();
695
696 // Now that the BOT and the object header have been initialized,
697 // we can update top of the "starts humongous" region.
698 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
699 "new_top should be in this region");
700 first_hr->set_top(new_top);
701 if (_hr_printer.is_active()) {
702 HeapWord* bottom = first_hr->bottom();
703 HeapWord* end = first_hr->orig_end();
704 if ((first + 1) == last) {
705 // the series has a single humongous region
706 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
707 } else {
708 // the series has more than one humongous regions
709 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
710 }
711 }
712
713 // Now, we will update the top fields of the "continues humongous"
714 // regions. The reason we need to do this is that, otherwise,
715 // these regions would look empty and this will confuse parts of
716 // G1. For example, the code that looks for a consecutive number
717 // of empty regions will consider them empty and try to
718 // re-allocate them. We can extend is_empty() to also include
719 // !is_continues_humongous(), but it is easier to just update the top
720 // fields here. The way we set top for all regions (i.e., top ==
721 // end for all regions but the last one, top == new_top for the
722 // last one) is actually used when we will free up the humongous
723 // region in free_humongous_region().
724 hr = NULL;
725 for (uint i = first + 1; i < last; ++i) {
726 hr = region_at(i);
727 if ((i + 1) == last) {
728 // last continues humongous region
729 assert(hr->bottom() < new_top && new_top <= hr->end(),
730 "new_top should fall on this region");
731 hr->set_top(new_top);
732 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
733 } else {
734 // not last one
735 assert(new_top > hr->end(), "new_top should be above this region");
736 hr->set_top(hr->end());
737 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
738 }
739 }
740 // If we have continues humongous regions (hr != NULL), then the
741 // end of the last one should match new_end and its top should
742 // match new_top.
743 assert(hr == NULL ||
744 (hr->end() == new_end && hr->top() == new_top), "sanity");
745 check_bitmaps("Humongous Region Allocation", first_hr);
746
747 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
748 _allocator->increase_used(first_hr->used());
749 _humongous_set.add(first_hr);
750
751 return new_obj;
752 }
753
754 // If could fit into free regions w/o expansion, try.
755 // Otherwise, if can expand, do so.
756 // Otherwise, if using ex regions might help, try with ex given back.
757 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
758 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
759
760 verify_region_sets_optional();
761
762 uint first = G1_NO_HRM_INDEX;
763 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
764
765 if (obj_regions == 1) {
766 // Only one region to allocate, try to use a fast path by directly allocating
767 // from the free lists. Do not try to expand here, we will potentially do that
768 // later.
769 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
770 if (hr != NULL) {
771 first = hr->hrm_index();
772 }
773 } else {
774 // We can't allocate humongous regions spanning more than one region while
775 // cleanupComplete() is running, since some of the regions we find to be
776 // empty might not yet be added to the free list. It is not straightforward
777 // to know in which list they are on so that we can remove them. We only
778 // need to do this if we need to allocate more than one region to satisfy the
779 // current humongous allocation request. If we are only allocating one region
780 // we use the one-region region allocation code (see above), that already
781 // potentially waits for regions from the secondary free list.
782 wait_while_free_regions_coming();
783 append_secondary_free_list_if_not_empty_with_lock();
784
785 // Policy: Try only empty regions (i.e. already committed first). Maybe we
786 // are lucky enough to find some.
787 first = _hrm.find_contiguous_only_empty(obj_regions);
788 if (first != G1_NO_HRM_INDEX) {
789 _hrm.allocate_free_regions_starting_at(first, obj_regions);
790 }
791 }
792
793 if (first == G1_NO_HRM_INDEX) {
794 // Policy: We could not find enough regions for the humongous object in the
795 // free list. Look through the heap to find a mix of free and uncommitted regions.
796 // If so, try expansion.
797 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
798 if (first != G1_NO_HRM_INDEX) {
799 // We found something. Make sure these regions are committed, i.e. expand
800 // the heap. Alternatively we could do a defragmentation GC.
801 ergo_verbose1(ErgoHeapSizing,
802 "attempt heap expansion",
803 ergo_format_reason("humongous allocation request failed")
804 ergo_format_byte("allocation request"),
805 word_size * HeapWordSize);
806
807 _hrm.expand_at(first, obj_regions);
808 g1_policy()->record_new_heap_size(num_regions());
809
810 #ifdef ASSERT
811 for (uint i = first; i < first + obj_regions; ++i) {
812 HeapRegion* hr = region_at(i);
813 assert(hr->is_free(), "sanity");
814 assert(hr->is_empty(), "sanity");
815 assert(is_on_master_free_list(hr), "sanity");
816 }
817 #endif
818 _hrm.allocate_free_regions_starting_at(first, obj_regions);
819 } else {
820 // Policy: Potentially trigger a defragmentation GC.
821 }
822 }
823
824 HeapWord* result = NULL;
825 if (first != G1_NO_HRM_INDEX) {
826 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
827 word_size, context);
828 assert(result != NULL, "it should always return a valid result");
829
830 // A successful humongous object allocation changes the used space
831 // information of the old generation so we need to recalculate the
832 // sizes and update the jstat counters here.
833 g1mm()->update_sizes();
834 }
835
836 verify_region_sets_optional();
837
838 return result;
839 }
840
841 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
842 assert_heap_not_locked_and_not_at_safepoint();
843 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
844
845 unsigned int dummy_gc_count_before;
846 int dummy_gclocker_retry_count = 0;
847 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
848 }
849
850 HeapWord*
851 G1CollectedHeap::mem_allocate(size_t word_size,
852 bool* gc_overhead_limit_was_exceeded) {
853 assert_heap_not_locked_and_not_at_safepoint();
854
855 // Loop until the allocation is satisfied, or unsatisfied after GC.
856 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
857 unsigned int gc_count_before;
858
859 HeapWord* result = NULL;
860 if (!is_humongous(word_size)) {
861 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
862 } else {
863 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
864 }
865 if (result != NULL) {
866 return result;
867 }
868
869 // Create the garbage collection operation...
870 VM_G1CollectForAllocation op(gc_count_before, word_size);
871 op.set_allocation_context(AllocationContext::current());
872
873 // ...and get the VM thread to execute it.
874 VMThread::execute(&op);
875
876 if (op.prologue_succeeded() && op.pause_succeeded()) {
877 // If the operation was successful we'll return the result even
878 // if it is NULL. If the allocation attempt failed immediately
879 // after a Full GC, it's unlikely we'll be able to allocate now.
880 HeapWord* result = op.result();
881 if (result != NULL && !is_humongous(word_size)) {
882 // Allocations that take place on VM operations do not do any
883 // card dirtying and we have to do it here. We only have to do
884 // this for non-humongous allocations, though.
885 dirty_young_block(result, word_size);
886 }
887 return result;
888 } else {
889 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
890 return NULL;
891 }
892 assert(op.result() == NULL,
893 "the result should be NULL if the VM op did not succeed");
894 }
895
896 // Give a warning if we seem to be looping forever.
897 if ((QueuedAllocationWarningCount > 0) &&
898 (try_count % QueuedAllocationWarningCount == 0)) {
899 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
900 }
901 }
902
903 ShouldNotReachHere();
904 return NULL;
905 }
906
907 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
908 AllocationContext_t context,
909 unsigned int *gc_count_before_ret,
910 int* gclocker_retry_count_ret) {
911 // Make sure you read the note in attempt_allocation_humongous().
912
913 assert_heap_not_locked_and_not_at_safepoint();
914 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
915 "be called for humongous allocation requests");
916
917 // We should only get here after the first-level allocation attempt
918 // (attempt_allocation()) failed to allocate.
919
920 // We will loop until a) we manage to successfully perform the
921 // allocation or b) we successfully schedule a collection which
922 // fails to perform the allocation. b) is the only case when we'll
923 // return NULL.
924 HeapWord* result = NULL;
925 for (int try_count = 1; /* we'll return */; try_count += 1) {
926 bool should_try_gc;
927 unsigned int gc_count_before;
928
929 {
930 MutexLockerEx x(Heap_lock);
931 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
932 false /* bot_updates */);
933 if (result != NULL) {
934 return result;
935 }
936
937 // If we reach here, attempt_allocation_locked() above failed to
938 // allocate a new region. So the mutator alloc region should be NULL.
939 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
940
941 if (GC_locker::is_active_and_needs_gc()) {
942 if (g1_policy()->can_expand_young_list()) {
943 // No need for an ergo verbose message here,
944 // can_expand_young_list() does this when it returns true.
945 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
946 false /* bot_updates */);
947 if (result != NULL) {
948 return result;
949 }
950 }
951 should_try_gc = false;
952 } else {
953 // The GCLocker may not be active but the GCLocker initiated
954 // GC may not yet have been performed (GCLocker::needs_gc()
955 // returns true). In this case we do not try this GC and
956 // wait until the GCLocker initiated GC is performed, and
957 // then retry the allocation.
958 if (GC_locker::needs_gc()) {
959 should_try_gc = false;
960 } else {
961 // Read the GC count while still holding the Heap_lock.
962 gc_count_before = total_collections();
963 should_try_gc = true;
964 }
965 }
966 }
967
968 if (should_try_gc) {
969 bool succeeded;
970 result = do_collection_pause(word_size, gc_count_before, &succeeded,
971 GCCause::_g1_inc_collection_pause);
972 if (result != NULL) {
973 assert(succeeded, "only way to get back a non-NULL result");
974 return result;
975 }
976
977 if (succeeded) {
978 // If we get here we successfully scheduled a collection which
979 // failed to allocate. No point in trying to allocate
980 // further. We'll just return NULL.
981 MutexLockerEx x(Heap_lock);
982 *gc_count_before_ret = total_collections();
983 return NULL;
984 }
985 } else {
986 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
987 MutexLockerEx x(Heap_lock);
988 *gc_count_before_ret = total_collections();
989 return NULL;
990 }
991 // The GCLocker is either active or the GCLocker initiated
992 // GC has not yet been performed. Stall until it is and
993 // then retry the allocation.
994 GC_locker::stall_until_clear();
995 (*gclocker_retry_count_ret) += 1;
996 }
997
998 // We can reach here if we were unsuccessful in scheduling a
999 // collection (because another thread beat us to it) or if we were
1000 // stalled due to the GC locker. In either can we should retry the
1001 // allocation attempt in case another thread successfully
1002 // performed a collection and reclaimed enough space. We do the
1003 // first attempt (without holding the Heap_lock) here and the
1004 // follow-on attempt will be at the start of the next loop
1005 // iteration (after taking the Heap_lock).
1006 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
1007 false /* bot_updates */);
1008 if (result != NULL) {
1009 return result;
1010 }
1011
1012 // Give a warning if we seem to be looping forever.
1013 if ((QueuedAllocationWarningCount > 0) &&
1014 (try_count % QueuedAllocationWarningCount == 0)) {
1015 warning("G1CollectedHeap::attempt_allocation_slow() "
1016 "retries %d times", try_count);
1017 }
1018 }
1019
1020 ShouldNotReachHere();
1021 return NULL;
1022 }
1023
1024 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1025 unsigned int * gc_count_before_ret,
1026 int* gclocker_retry_count_ret) {
1027 // The structure of this method has a lot of similarities to
1028 // attempt_allocation_slow(). The reason these two were not merged
1029 // into a single one is that such a method would require several "if
1030 // allocation is not humongous do this, otherwise do that"
1031 // conditional paths which would obscure its flow. In fact, an early
1032 // version of this code did use a unified method which was harder to
1033 // follow and, as a result, it had subtle bugs that were hard to
1034 // track down. So keeping these two methods separate allows each to
1035 // be more readable. It will be good to keep these two in sync as
1036 // much as possible.
1037
1038 assert_heap_not_locked_and_not_at_safepoint();
1039 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1040 "should only be called for humongous allocations");
1041
1042 // Humongous objects can exhaust the heap quickly, so we should check if we
1043 // need to start a marking cycle at each humongous object allocation. We do
1044 // the check before we do the actual allocation. The reason for doing it
1045 // before the allocation is that we avoid having to keep track of the newly
1046 // allocated memory while we do a GC.
1047 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1048 word_size)) {
1049 collect(GCCause::_g1_humongous_allocation);
1050 }
1051
1052 // We will loop until a) we manage to successfully perform the
1053 // allocation or b) we successfully schedule a collection which
1054 // fails to perform the allocation. b) is the only case when we'll
1055 // return NULL.
1056 HeapWord* result = NULL;
1057 for (int try_count = 1; /* we'll return */; try_count += 1) {
1058 bool should_try_gc;
1059 unsigned int gc_count_before;
1060
1061 {
1062 MutexLockerEx x(Heap_lock);
1063
1064 // Given that humongous objects are not allocated in young
1065 // regions, we'll first try to do the allocation without doing a
1066 // collection hoping that there's enough space in the heap.
1067 result = humongous_obj_allocate(word_size, AllocationContext::current());
1068 if (result != NULL) {
1069 return result;
1070 }
1071
1072 if (GC_locker::is_active_and_needs_gc()) {
1073 should_try_gc = false;
1074 } else {
1075 // The GCLocker may not be active but the GCLocker initiated
1076 // GC may not yet have been performed (GCLocker::needs_gc()
1077 // returns true). In this case we do not try this GC and
1078 // wait until the GCLocker initiated GC is performed, and
1079 // then retry the allocation.
1080 if (GC_locker::needs_gc()) {
1081 should_try_gc = false;
1082 } else {
1083 // Read the GC count while still holding the Heap_lock.
1084 gc_count_before = total_collections();
1085 should_try_gc = true;
1086 }
1087 }
1088 }
1089
1090 if (should_try_gc) {
1091 // If we failed to allocate the humongous object, we should try to
1092 // do a collection pause (if we're allowed) in case it reclaims
1093 // enough space for the allocation to succeed after the pause.
1094
1095 bool succeeded;
1096 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1097 GCCause::_g1_humongous_allocation);
1098 if (result != NULL) {
1099 assert(succeeded, "only way to get back a non-NULL result");
1100 return result;
1101 }
1102
1103 if (succeeded) {
1104 // If we get here we successfully scheduled a collection which
1105 // failed to allocate. No point in trying to allocate
1106 // further. We'll just return NULL.
1107 MutexLockerEx x(Heap_lock);
1108 *gc_count_before_ret = total_collections();
1109 return NULL;
1110 }
1111 } else {
1112 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1113 MutexLockerEx x(Heap_lock);
1114 *gc_count_before_ret = total_collections();
1115 return NULL;
1116 }
1117 // The GCLocker is either active or the GCLocker initiated
1118 // GC has not yet been performed. Stall until it is and
1119 // then retry the allocation.
1120 GC_locker::stall_until_clear();
1121 (*gclocker_retry_count_ret) += 1;
1122 }
1123
1124 // We can reach here if we were unsuccessful in scheduling a
1125 // collection (because another thread beat us to it) or if we were
1126 // stalled due to the GC locker. In either can we should retry the
1127 // allocation attempt in case another thread successfully
1128 // performed a collection and reclaimed enough space. Give a
1129 // warning if we seem to be looping forever.
1130
1131 if ((QueuedAllocationWarningCount > 0) &&
1132 (try_count % QueuedAllocationWarningCount == 0)) {
1133 warning("G1CollectedHeap::attempt_allocation_humongous() "
1134 "retries %d times", try_count);
1135 }
1136 }
1137
1138 ShouldNotReachHere();
1139 return NULL;
1140 }
1141
1142 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1143 AllocationContext_t context,
1144 bool expect_null_mutator_alloc_region) {
1145 assert_at_safepoint(true /* should_be_vm_thread */);
1146 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1147 !expect_null_mutator_alloc_region,
1148 "the current alloc region was unexpectedly found to be non-NULL");
1149
1150 if (!is_humongous(word_size)) {
1151 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1152 false /* bot_updates */);
1153 } else {
1154 HeapWord* result = humongous_obj_allocate(word_size, context);
1155 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1156 g1_policy()->set_initiate_conc_mark_if_possible();
1157 }
1158 return result;
1159 }
1160
1161 ShouldNotReachHere();
1162 }
1163
1164 class PostMCRemSetClearClosure: public HeapRegionClosure {
1165 G1CollectedHeap* _g1h;
1166 ModRefBarrierSet* _mr_bs;
1167 public:
1168 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1169 _g1h(g1h), _mr_bs(mr_bs) {}
1170
1171 bool doHeapRegion(HeapRegion* r) {
1172 HeapRegionRemSet* hrrs = r->rem_set();
1173
1174 if (r->is_continues_humongous()) {
1175 // We'll assert that the strong code root list and RSet is empty
1176 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1177 assert(hrrs->occupied() == 0, "RSet should be empty");
1178 return false;
1179 }
1180
1181 _g1h->reset_gc_time_stamps(r);
1182 hrrs->clear();
1183 // You might think here that we could clear just the cards
1184 // corresponding to the used region. But no: if we leave a dirty card
1185 // in a region we might allocate into, then it would prevent that card
1186 // from being enqueued, and cause it to be missed.
1187 // Re: the performance cost: we shouldn't be doing full GC anyway!
1188 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1189
1190 return false;
1191 }
1192 };
1193
1194 void G1CollectedHeap::clear_rsets_post_compaction() {
1195 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1196 heap_region_iterate(&rs_clear);
1197 }
1198
1199 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1200 G1CollectedHeap* _g1h;
1201 UpdateRSOopClosure _cl;
1202 int _worker_i;
1203 public:
1204 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1205 _cl(g1->g1_rem_set(), worker_i),
1206 _worker_i(worker_i),
1207 _g1h(g1)
1208 { }
1209
1210 bool doHeapRegion(HeapRegion* r) {
1211 if (!r->is_continues_humongous()) {
1212 _cl.set_from(r);
1213 r->oop_iterate(&_cl);
1214 }
1215 return false;
1216 }
1217 };
1218
1219 class ParRebuildRSTask: public AbstractGangTask {
1220 G1CollectedHeap* _g1;
1221 HeapRegionClaimer _hrclaimer;
1222
1223 public:
1224 ParRebuildRSTask(G1CollectedHeap* g1) :
1225 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1226
1227 void work(uint worker_id) {
1228 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1229 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1230 }
1231 };
1232
1233 class PostCompactionPrinterClosure: public HeapRegionClosure {
1234 private:
1235 G1HRPrinter* _hr_printer;
1236 public:
1237 bool doHeapRegion(HeapRegion* hr) {
1238 assert(!hr->is_young(), "not expecting to find young regions");
1239 if (hr->is_free()) {
1240 // We only generate output for non-empty regions.
1241 } else if (hr->is_starts_humongous()) {
1242 if (hr->region_num() == 1) {
1243 // single humongous region
1244 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1245 } else {
1246 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1247 }
1248 } else if (hr->is_continues_humongous()) {
1249 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1250 } else if (hr->is_old()) {
1251 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1252 } else {
1253 ShouldNotReachHere();
1254 }
1255 return false;
1256 }
1257
1258 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1259 : _hr_printer(hr_printer) { }
1260 };
1261
1262 void G1CollectedHeap::print_hrm_post_compaction() {
1263 PostCompactionPrinterClosure cl(hr_printer());
1264 heap_region_iterate(&cl);
1265 }
1266
1267 bool G1CollectedHeap::do_collection(bool explicit_gc,
1268 bool clear_all_soft_refs,
1269 size_t word_size) {
1270 assert_at_safepoint(true /* should_be_vm_thread */);
1271
1272 if (GC_locker::check_active_before_gc()) {
1273 return false;
1274 }
1275
1276 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1277 gc_timer->register_gc_start();
1278
1279 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1280 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1281
1282 SvcGCMarker sgcm(SvcGCMarker::FULL);
1283 ResourceMark rm;
1284
1285 print_heap_before_gc();
1286 trace_heap_before_gc(gc_tracer);
1287
1288 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1289
1290 verify_region_sets_optional();
1291
1292 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1293 collector_policy()->should_clear_all_soft_refs();
1294
1295 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1296
1297 {
1298 IsGCActiveMark x;
1299
1300 // Timing
1301 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1302 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1303 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1304
1305 {
1306 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1307 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1308 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1309
1310 double start = os::elapsedTime();
1311 g1_policy()->record_full_collection_start();
1312
1313 // Note: When we have a more flexible GC logging framework that
1314 // allows us to add optional attributes to a GC log record we
1315 // could consider timing and reporting how long we wait in the
1316 // following two methods.
1317 wait_while_free_regions_coming();
1318 // If we start the compaction before the CM threads finish
1319 // scanning the root regions we might trip them over as we'll
1320 // be moving objects / updating references. So let's wait until
1321 // they are done. By telling them to abort, they should complete
1322 // early.
1323 _cm->root_regions()->abort();
1324 _cm->root_regions()->wait_until_scan_finished();
1325 append_secondary_free_list_if_not_empty_with_lock();
1326
1327 gc_prologue(true);
1328 increment_total_collections(true /* full gc */);
1329 increment_old_marking_cycles_started();
1330
1331 assert(used() == recalculate_used(), "Should be equal");
1332
1333 verify_before_gc();
1334
1335 check_bitmaps("Full GC Start");
1336 pre_full_gc_dump(gc_timer);
1337
1338 COMPILER2_PRESENT(DerivedPointerTable::clear());
1339
1340 // Disable discovery and empty the discovered lists
1341 // for the CM ref processor.
1342 ref_processor_cm()->disable_discovery();
1343 ref_processor_cm()->abandon_partial_discovery();
1344 ref_processor_cm()->verify_no_references_recorded();
1345
1346 // Abandon current iterations of concurrent marking and concurrent
1347 // refinement, if any are in progress. We have to do this before
1348 // wait_until_scan_finished() below.
1349 concurrent_mark()->abort();
1350
1351 // Make sure we'll choose a new allocation region afterwards.
1352 _allocator->release_mutator_alloc_region();
1353 _allocator->abandon_gc_alloc_regions();
1354 g1_rem_set()->cleanupHRRS();
1355
1356 // We should call this after we retire any currently active alloc
1357 // regions so that all the ALLOC / RETIRE events are generated
1358 // before the start GC event.
1359 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1360
1361 // We may have added regions to the current incremental collection
1362 // set between the last GC or pause and now. We need to clear the
1363 // incremental collection set and then start rebuilding it afresh
1364 // after this full GC.
1365 abandon_collection_set(g1_policy()->inc_cset_head());
1366 g1_policy()->clear_incremental_cset();
1367 g1_policy()->stop_incremental_cset_building();
1368
1369 tear_down_region_sets(false /* free_list_only */);
1370 g1_policy()->set_gcs_are_young(true);
1371
1372 // See the comments in g1CollectedHeap.hpp and
1373 // G1CollectedHeap::ref_processing_init() about
1374 // how reference processing currently works in G1.
1375
1376 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1377 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1378
1379 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1380 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1381
1382 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1383 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1384
1385 // Do collection work
1386 {
1387 HandleMark hm; // Discard invalid handles created during gc
1388 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1389 }
1390
1391 assert(num_free_regions() == 0, "we should not have added any free regions");
1392 rebuild_region_sets(false /* free_list_only */);
1393
1394 // Enqueue any discovered reference objects that have
1395 // not been removed from the discovered lists.
1396 ref_processor_stw()->enqueue_discovered_references();
1397
1398 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1399
1400 MemoryService::track_memory_usage();
1401
1402 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1403 ref_processor_stw()->verify_no_references_recorded();
1404
1405 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1406 ClassLoaderDataGraph::purge();
1407 MetaspaceAux::verify_metrics();
1408
1409 // Note: since we've just done a full GC, concurrent
1410 // marking is no longer active. Therefore we need not
1411 // re-enable reference discovery for the CM ref processor.
1412 // That will be done at the start of the next marking cycle.
1413 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1414 ref_processor_cm()->verify_no_references_recorded();
1415
1416 reset_gc_time_stamp();
1417 // Since everything potentially moved, we will clear all remembered
1418 // sets, and clear all cards. Later we will rebuild remembered
1419 // sets. We will also reset the GC time stamps of the regions.
1420 clear_rsets_post_compaction();
1421 check_gc_time_stamps();
1422
1423 // Resize the heap if necessary.
1424 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1425
1426 if (_hr_printer.is_active()) {
1427 // We should do this after we potentially resize the heap so
1428 // that all the COMMIT / UNCOMMIT events are generated before
1429 // the end GC event.
1430
1431 print_hrm_post_compaction();
1432 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1433 }
1434
1435 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1436 if (hot_card_cache->use_cache()) {
1437 hot_card_cache->reset_card_counts();
1438 hot_card_cache->reset_hot_cache();
1439 }
1440
1441 // Rebuild remembered sets of all regions.
1442 uint n_workers =
1443 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1444 workers()->active_workers(),
1445 Threads::number_of_non_daemon_threads());
1446 assert(UseDynamicNumberOfGCThreads ||
1447 n_workers == workers()->total_workers(),
1448 "If not dynamic should be using all the workers");
1449 workers()->set_active_workers(n_workers);
1450 // Set parallel threads in the heap (_n_par_threads) only
1451 // before a parallel phase and always reset it to 0 after
1452 // the phase so that the number of parallel threads does
1453 // no get carried forward to a serial phase where there
1454 // may be code that is "possibly_parallel".
1455 set_par_threads(n_workers);
1456
1457 ParRebuildRSTask rebuild_rs_task(this);
1458 assert(UseDynamicNumberOfGCThreads ||
1459 workers()->active_workers() == workers()->total_workers(),
1460 "Unless dynamic should use total workers");
1461 // Use the most recent number of active workers
1462 assert(workers()->active_workers() > 0,
1463 "Active workers not properly set");
1464 set_par_threads(workers()->active_workers());
1465 workers()->run_task(&rebuild_rs_task);
1466 set_par_threads(0);
1467
1468 // Rebuild the strong code root lists for each region
1469 rebuild_strong_code_roots();
1470
1471 if (true) { // FIXME
1472 MetaspaceGC::compute_new_size();
1473 }
1474
1475 #ifdef TRACESPINNING
1476 ParallelTaskTerminator::print_termination_counts();
1477 #endif
1478
1479 // Discard all rset updates
1480 JavaThread::dirty_card_queue_set().abandon_logs();
1481 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1482
1483 _young_list->reset_sampled_info();
1484 // At this point there should be no regions in the
1485 // entire heap tagged as young.
1486 assert(check_young_list_empty(true /* check_heap */),
1487 "young list should be empty at this point");
1488
1489 // Update the number of full collections that have been completed.
1490 increment_old_marking_cycles_completed(false /* concurrent */);
1491
1492 _hrm.verify_optional();
1493 verify_region_sets_optional();
1494
1495 verify_after_gc();
1496
1497 // Clear the previous marking bitmap, if needed for bitmap verification.
1498 // Note we cannot do this when we clear the next marking bitmap in
1499 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1500 // objects marked during a full GC against the previous bitmap.
1501 // But we need to clear it before calling check_bitmaps below since
1502 // the full GC has compacted objects and updated TAMS but not updated
1503 // the prev bitmap.
1504 if (G1VerifyBitmaps) {
1505 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1506 }
1507 check_bitmaps("Full GC End");
1508
1509 // Start a new incremental collection set for the next pause
1510 assert(g1_policy()->collection_set() == NULL, "must be");
1511 g1_policy()->start_incremental_cset_building();
1512
1513 clear_cset_fast_test();
1514
1515 _allocator->init_mutator_alloc_region();
1516
1517 double end = os::elapsedTime();
1518 g1_policy()->record_full_collection_end();
1519
1520 if (G1Log::fine()) {
1521 g1_policy()->print_heap_transition();
1522 }
1523
1524 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1525 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1526 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1527 // before any GC notifications are raised.
1528 g1mm()->update_sizes();
1529
1530 gc_epilogue(true);
1531 }
1532
1533 if (G1Log::finer()) {
1534 g1_policy()->print_detailed_heap_transition(true /* full */);
1535 }
1536
1537 print_heap_after_gc();
1538 trace_heap_after_gc(gc_tracer);
1539
1540 post_full_gc_dump(gc_timer);
1541
1542 gc_timer->register_gc_end();
1543 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1544 }
1545
1546 return true;
1547 }
1548
1549 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1550 // do_collection() will return whether it succeeded in performing
1551 // the GC. Currently, there is no facility on the
1552 // do_full_collection() API to notify the caller than the collection
1553 // did not succeed (e.g., because it was locked out by the GC
1554 // locker). So, right now, we'll ignore the return value.
1555 bool dummy = do_collection(true, /* explicit_gc */
1556 clear_all_soft_refs,
1557 0 /* word_size */);
1558 }
1559
1560 // This code is mostly copied from TenuredGeneration.
1561 void
1562 G1CollectedHeap::
1563 resize_if_necessary_after_full_collection(size_t word_size) {
1564 // Include the current allocation, if any, and bytes that will be
1565 // pre-allocated to support collections, as "used".
1566 const size_t used_after_gc = used();
1567 const size_t capacity_after_gc = capacity();
1568 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1569
1570 // This is enforced in arguments.cpp.
1571 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1572 "otherwise the code below doesn't make sense");
1573
1574 // We don't have floating point command-line arguments
1575 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1576 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1577 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1578 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1579
1580 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1581 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1582
1583 // We have to be careful here as these two calculations can overflow
1584 // 32-bit size_t's.
1585 double used_after_gc_d = (double) used_after_gc;
1586 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1587 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1588
1589 // Let's make sure that they are both under the max heap size, which
1590 // by default will make them fit into a size_t.
1591 double desired_capacity_upper_bound = (double) max_heap_size;
1592 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1593 desired_capacity_upper_bound);
1594 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1595 desired_capacity_upper_bound);
1596
1597 // We can now safely turn them into size_t's.
1598 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1599 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1600
1601 // This assert only makes sense here, before we adjust them
1602 // with respect to the min and max heap size.
1603 assert(minimum_desired_capacity <= maximum_desired_capacity,
1604 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1605 "maximum_desired_capacity = "SIZE_FORMAT,
1606 minimum_desired_capacity, maximum_desired_capacity));
1607
1608 // Should not be greater than the heap max size. No need to adjust
1609 // it with respect to the heap min size as it's a lower bound (i.e.,
1610 // we'll try to make the capacity larger than it, not smaller).
1611 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1612 // Should not be less than the heap min size. No need to adjust it
1613 // with respect to the heap max size as it's an upper bound (i.e.,
1614 // we'll try to make the capacity smaller than it, not greater).
1615 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1616
1617 if (capacity_after_gc < minimum_desired_capacity) {
1618 // Don't expand unless it's significant
1619 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1620 ergo_verbose4(ErgoHeapSizing,
1621 "attempt heap expansion",
1622 ergo_format_reason("capacity lower than "
1623 "min desired capacity after Full GC")
1624 ergo_format_byte("capacity")
1625 ergo_format_byte("occupancy")
1626 ergo_format_byte_perc("min desired capacity"),
1627 capacity_after_gc, used_after_gc,
1628 minimum_desired_capacity, (double) MinHeapFreeRatio);
1629 expand(expand_bytes);
1630
1631 // No expansion, now see if we want to shrink
1632 } else if (capacity_after_gc > maximum_desired_capacity) {
1633 // Capacity too large, compute shrinking size
1634 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1635 ergo_verbose4(ErgoHeapSizing,
1636 "attempt heap shrinking",
1637 ergo_format_reason("capacity higher than "
1638 "max desired capacity after Full GC")
1639 ergo_format_byte("capacity")
1640 ergo_format_byte("occupancy")
1641 ergo_format_byte_perc("max desired capacity"),
1642 capacity_after_gc, used_after_gc,
1643 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1644 shrink(shrink_bytes);
1645 }
1646 }
1647
1648
1649 HeapWord*
1650 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1651 AllocationContext_t context,
1652 bool* succeeded) {
1653 assert_at_safepoint(true /* should_be_vm_thread */);
1654
1655 *succeeded = true;
1656 // Let's attempt the allocation first.
1657 HeapWord* result =
1658 attempt_allocation_at_safepoint(word_size,
1659 context,
1660 false /* expect_null_mutator_alloc_region */);
1661 if (result != NULL) {
1662 assert(*succeeded, "sanity");
1663 return result;
1664 }
1665
1666 // In a G1 heap, we're supposed to keep allocation from failing by
1667 // incremental pauses. Therefore, at least for now, we'll favor
1668 // expansion over collection. (This might change in the future if we can
1669 // do something smarter than full collection to satisfy a failed alloc.)
1670 result = expand_and_allocate(word_size, context);
1671 if (result != NULL) {
1672 assert(*succeeded, "sanity");
1673 return result;
1674 }
1675
1676 // Expansion didn't work, we'll try to do a Full GC.
1677 bool gc_succeeded = do_collection(false, /* explicit_gc */
1678 false, /* clear_all_soft_refs */
1679 word_size);
1680 if (!gc_succeeded) {
1681 *succeeded = false;
1682 return NULL;
1683 }
1684
1685 // Retry the allocation
1686 result = attempt_allocation_at_safepoint(word_size,
1687 context,
1688 true /* expect_null_mutator_alloc_region */);
1689 if (result != NULL) {
1690 assert(*succeeded, "sanity");
1691 return result;
1692 }
1693
1694 // Then, try a Full GC that will collect all soft references.
1695 gc_succeeded = do_collection(false, /* explicit_gc */
1696 true, /* clear_all_soft_refs */
1697 word_size);
1698 if (!gc_succeeded) {
1699 *succeeded = false;
1700 return NULL;
1701 }
1702
1703 // Retry the allocation once more
1704 result = attempt_allocation_at_safepoint(word_size,
1705 context,
1706 true /* expect_null_mutator_alloc_region */);
1707 if (result != NULL) {
1708 assert(*succeeded, "sanity");
1709 return result;
1710 }
1711
1712 assert(!collector_policy()->should_clear_all_soft_refs(),
1713 "Flag should have been handled and cleared prior to this point");
1714
1715 // What else? We might try synchronous finalization later. If the total
1716 // space available is large enough for the allocation, then a more
1717 // complete compaction phase than we've tried so far might be
1718 // appropriate.
1719 assert(*succeeded, "sanity");
1720 return NULL;
1721 }
1722
1723 // Attempting to expand the heap sufficiently
1724 // to support an allocation of the given "word_size". If
1725 // successful, perform the allocation and return the address of the
1726 // allocated block, or else "NULL".
1727
1728 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1729 assert_at_safepoint(true /* should_be_vm_thread */);
1730
1731 verify_region_sets_optional();
1732
1733 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1734 ergo_verbose1(ErgoHeapSizing,
1735 "attempt heap expansion",
1736 ergo_format_reason("allocation request failed")
1737 ergo_format_byte("allocation request"),
1738 word_size * HeapWordSize);
1739 if (expand(expand_bytes)) {
1740 _hrm.verify_optional();
1741 verify_region_sets_optional();
1742 return attempt_allocation_at_safepoint(word_size,
1743 context,
1744 false /* expect_null_mutator_alloc_region */);
1745 }
1746 return NULL;
1747 }
1748
1749 bool G1CollectedHeap::expand(size_t expand_bytes) {
1750 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1751 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1752 HeapRegion::GrainBytes);
1753 ergo_verbose2(ErgoHeapSizing,
1754 "expand the heap",
1755 ergo_format_byte("requested expansion amount")
1756 ergo_format_byte("attempted expansion amount"),
1757 expand_bytes, aligned_expand_bytes);
1758
1759 if (is_maximal_no_gc()) {
1760 ergo_verbose0(ErgoHeapSizing,
1761 "did not expand the heap",
1762 ergo_format_reason("heap already fully expanded"));
1763 return false;
1764 }
1765
1766 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1767 assert(regions_to_expand > 0, "Must expand by at least one region");
1768
1769 uint expanded_by = _hrm.expand_by(regions_to_expand);
1770
1771 if (expanded_by > 0) {
1772 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1773 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1774 g1_policy()->record_new_heap_size(num_regions());
1775 } else {
1776 ergo_verbose0(ErgoHeapSizing,
1777 "did not expand the heap",
1778 ergo_format_reason("heap expansion operation failed"));
1779 // The expansion of the virtual storage space was unsuccessful.
1780 // Let's see if it was because we ran out of swap.
1781 if (G1ExitOnExpansionFailure &&
1782 _hrm.available() >= regions_to_expand) {
1783 // We had head room...
1784 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1785 }
1786 }
1787 return regions_to_expand > 0;
1788 }
1789
1790 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1791 size_t aligned_shrink_bytes =
1792 ReservedSpace::page_align_size_down(shrink_bytes);
1793 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1794 HeapRegion::GrainBytes);
1795 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1796
1797 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1798 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1799
1800 ergo_verbose3(ErgoHeapSizing,
1801 "shrink the heap",
1802 ergo_format_byte("requested shrinking amount")
1803 ergo_format_byte("aligned shrinking amount")
1804 ergo_format_byte("attempted shrinking amount"),
1805 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1806 if (num_regions_removed > 0) {
1807 g1_policy()->record_new_heap_size(num_regions());
1808 } else {
1809 ergo_verbose0(ErgoHeapSizing,
1810 "did not shrink the heap",
1811 ergo_format_reason("heap shrinking operation failed"));
1812 }
1813 }
1814
1815 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1816 verify_region_sets_optional();
1817
1818 // We should only reach here at the end of a Full GC which means we
1819 // should not not be holding to any GC alloc regions. The method
1820 // below will make sure of that and do any remaining clean up.
1821 _allocator->abandon_gc_alloc_regions();
1822
1823 // Instead of tearing down / rebuilding the free lists here, we
1824 // could instead use the remove_all_pending() method on free_list to
1825 // remove only the ones that we need to remove.
1826 tear_down_region_sets(true /* free_list_only */);
1827 shrink_helper(shrink_bytes);
1828 rebuild_region_sets(true /* free_list_only */);
1829
1830 _hrm.verify_optional();
1831 verify_region_sets_optional();
1832 }
1833
1834 // Public methods.
1835
1836 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1837 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1838 #endif // _MSC_VER
1839
1840
1841 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1842 SharedHeap(policy_),
1843 _g1_policy(policy_),
1844 _dirty_card_queue_set(false),
1845 _into_cset_dirty_card_queue_set(false),
1846 _is_alive_closure_cm(this),
1847 _is_alive_closure_stw(this),
1848 _ref_processor_cm(NULL),
1849 _ref_processor_stw(NULL),
1850 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1851 _bot_shared(NULL),
1852 _evac_failure_scan_stack(NULL),
1853 _mark_in_progress(false),
1854 _cg1r(NULL),
1855 _g1mm(NULL),
1856 _refine_cte_cl(NULL),
1857 _full_collection(false),
1858 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1859 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1860 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1861 _humongous_is_live(),
1862 _has_humongous_reclaim_candidates(false),
1863 _free_regions_coming(false),
1864 _young_list(new YoungList(this)),
1865 _gc_time_stamp(0),
1866 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1867 _old_plab_stats(OldPLABSize, PLABWeight),
1868 _expand_heap_after_alloc_failure(true),
1869 _surviving_young_words(NULL),
1870 _old_marking_cycles_started(0),
1871 _old_marking_cycles_completed(0),
1872 _concurrent_cycle_started(false),
1873 _heap_summary_sent(false),
1874 _in_cset_fast_test(),
1875 _dirty_cards_region_list(NULL),
1876 _worker_cset_start_region(NULL),
1877 _worker_cset_start_region_time_stamp(NULL),
1878 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1879 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1880 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1881 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1882
1883 _g1h = this;
1884 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1885 vm_exit_during_initialization("Failed necessary allocation.");
1886 }
1887
1888 _allocator = G1Allocator::create_allocator(_g1h);
1889 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1890
1891 int n_queues = MAX2((int)ParallelGCThreads, 1);
1892 _task_queues = new RefToScanQueueSet(n_queues);
1893
1894 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1895 assert(n_rem_sets > 0, "Invariant.");
1896
1897 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1898 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1899 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1900
1901 for (int i = 0; i < n_queues; i++) {
1902 RefToScanQueue* q = new RefToScanQueue();
1903 q->initialize();
1904 _task_queues->register_queue(i, q);
1905 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1906 }
1907 clear_cset_start_regions();
1908
1909 // Initialize the G1EvacuationFailureALot counters and flags.
1910 NOT_PRODUCT(reset_evacuation_should_fail();)
1911
1912 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1913 }
1914
1915 jint G1CollectedHeap::initialize() {
1916 CollectedHeap::pre_initialize();
1917 os::enable_vtime();
1918
1919 G1Log::init();
1920
1921 // Necessary to satisfy locking discipline assertions.
1922
1923 MutexLocker x(Heap_lock);
1924
1925 // We have to initialize the printer before committing the heap, as
1926 // it will be used then.
1927 _hr_printer.set_active(G1PrintHeapRegions);
1928
1929 // While there are no constraints in the GC code that HeapWordSize
1930 // be any particular value, there are multiple other areas in the
1931 // system which believe this to be true (e.g. oop->object_size in some
1932 // cases incorrectly returns the size in wordSize units rather than
1933 // HeapWordSize).
1934 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1935
1936 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1937 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1938 size_t heap_alignment = collector_policy()->heap_alignment();
1939
1940 // Ensure that the sizes are properly aligned.
1941 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1942 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1943 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1944
1945 _refine_cte_cl = new RefineCardTableEntryClosure();
1946
1947 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1948
1949 // Reserve the maximum.
1950
1951 // When compressed oops are enabled, the preferred heap base
1952 // is calculated by subtracting the requested size from the
1953 // 32Gb boundary and using the result as the base address for
1954 // heap reservation. If the requested size is not aligned to
1955 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1956 // into the ReservedHeapSpace constructor) then the actual
1957 // base of the reserved heap may end up differing from the
1958 // address that was requested (i.e. the preferred heap base).
1959 // If this happens then we could end up using a non-optimal
1960 // compressed oops mode.
1961
1962 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1963 heap_alignment);
1964
1965 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1966
1967 // Create the gen rem set (and barrier set) for the entire reserved region.
1968 _rem_set = collector_policy()->create_rem_set(reserved_region(), 2);
1969 set_barrier_set(rem_set()->bs());
1970 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1971 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1972 return JNI_ENOMEM;
1973 }
1974
1975 // Also create a G1 rem set.
1976 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1977
1978 // Carve out the G1 part of the heap.
1979
1980 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1981 G1RegionToSpaceMapper* heap_storage =
1982 G1RegionToSpaceMapper::create_mapper(g1_rs,
1983 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1984 HeapRegion::GrainBytes,
1985 1,
1986 mtJavaHeap);
1987 heap_storage->set_mapping_changed_listener(&_listener);
1988
1989 // Reserve space for the block offset table. We do not support automatic uncommit
1990 // for the card table at this time. BOT only.
1991 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1992 G1RegionToSpaceMapper* bot_storage =
1993 G1RegionToSpaceMapper::create_mapper(bot_rs,
1994 os::vm_page_size(),
1995 HeapRegion::GrainBytes,
1996 G1BlockOffsetSharedArray::N_bytes,
1997 mtGC);
1998
1999 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2000 G1RegionToSpaceMapper* cardtable_storage =
2001 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
2002 os::vm_page_size(),
2003 HeapRegion::GrainBytes,
2004 G1BlockOffsetSharedArray::N_bytes,
2005 mtGC);
2006
2007 // Reserve space for the card counts table.
2008 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
2009 G1RegionToSpaceMapper* card_counts_storage =
2010 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
2011 os::vm_page_size(),
2012 HeapRegion::GrainBytes,
2013 G1BlockOffsetSharedArray::N_bytes,
2014 mtGC);
2015
2016 // Reserve space for prev and next bitmap.
2017 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2018
2019 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2020 G1RegionToSpaceMapper* prev_bitmap_storage =
2021 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
2022 os::vm_page_size(),
2023 HeapRegion::GrainBytes,
2024 CMBitMap::mark_distance(),
2025 mtGC);
2026
2027 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2028 G1RegionToSpaceMapper* next_bitmap_storage =
2029 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
2030 os::vm_page_size(),
2031 HeapRegion::GrainBytes,
2032 CMBitMap::mark_distance(),
2033 mtGC);
2034
2035 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2036 g1_barrier_set()->initialize(cardtable_storage);
2037 // Do later initialization work for concurrent refinement.
2038 _cg1r->init(card_counts_storage);
2039
2040 // 6843694 - ensure that the maximum region index can fit
2041 // in the remembered set structures.
2042 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2043 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2044
2045 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2046 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2047 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2048 "too many cards per region");
2049
2050 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2051
2052 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2053
2054 _g1h = this;
2055
2056 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2057 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2058
2059 // Create the ConcurrentMark data structure and thread.
2060 // (Must do this late, so that "max_regions" is defined.)
2061 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2062 if (_cm == NULL || !_cm->completed_initialization()) {
2063 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2064 return JNI_ENOMEM;
2065 }
2066 _cmThread = _cm->cmThread();
2067
2068 // Initialize the from_card cache structure of HeapRegionRemSet.
2069 HeapRegionRemSet::init_heap(max_regions());
2070
2071 // Now expand into the initial heap size.
2072 if (!expand(init_byte_size)) {
2073 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2074 return JNI_ENOMEM;
2075 }
2076
2077 // Perform any initialization actions delegated to the policy.
2078 g1_policy()->init();
2079
2080 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2081 SATB_Q_FL_lock,
2082 G1SATBProcessCompletedThreshold,
2083 Shared_SATB_Q_lock);
2084
2085 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2086 DirtyCardQ_CBL_mon,
2087 DirtyCardQ_FL_lock,
2088 concurrent_g1_refine()->yellow_zone(),
2089 concurrent_g1_refine()->red_zone(),
2090 Shared_DirtyCardQ_lock);
2091
2092 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2093 DirtyCardQ_CBL_mon,
2094 DirtyCardQ_FL_lock,
2095 -1, // never trigger processing
2096 -1, // no limit on length
2097 Shared_DirtyCardQ_lock,
2098 &JavaThread::dirty_card_queue_set());
2099
2100 // Initialize the card queue set used to hold cards containing
2101 // references into the collection set.
2102 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2103 DirtyCardQ_CBL_mon,
2104 DirtyCardQ_FL_lock,
2105 -1, // never trigger processing
2106 -1, // no limit on length
2107 Shared_DirtyCardQ_lock,
2108 &JavaThread::dirty_card_queue_set());
2109
2110 // In case we're keeping closure specialization stats, initialize those
2111 // counts and that mechanism.
2112 SpecializationStats::clear();
2113
2114 // Here we allocate the dummy HeapRegion that is required by the
2115 // G1AllocRegion class.
2116 HeapRegion* dummy_region = _hrm.get_dummy_region();
2117
2118 // We'll re-use the same region whether the alloc region will
2119 // require BOT updates or not and, if it doesn't, then a non-young
2120 // region will complain that it cannot support allocations without
2121 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2122 dummy_region->set_eden();
2123 // Make sure it's full.
2124 dummy_region->set_top(dummy_region->end());
2125 G1AllocRegion::setup(this, dummy_region);
2126
2127 _allocator->init_mutator_alloc_region();
2128
2129 // Do create of the monitoring and management support so that
2130 // values in the heap have been properly initialized.
2131 _g1mm = new G1MonitoringSupport(this);
2132
2133 G1StringDedup::initialize();
2134
2135 return JNI_OK;
2136 }
2137
2138 void G1CollectedHeap::stop() {
2139 // Stop all concurrent threads. We do this to make sure these threads
2140 // do not continue to execute and access resources (e.g. gclog_or_tty)
2141 // that are destroyed during shutdown.
2142 _cg1r->stop();
2143 _cmThread->stop();
2144 if (G1StringDedup::is_enabled()) {
2145 G1StringDedup::stop();
2146 }
2147 }
2148
2149 void G1CollectedHeap::clear_humongous_is_live_table() {
2150 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2151 _humongous_is_live.clear();
2152 }
2153
2154 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2155 return HeapRegion::max_region_size();
2156 }
2157
2158 void G1CollectedHeap::ref_processing_init() {
2159 // Reference processing in G1 currently works as follows:
2160 //
2161 // * There are two reference processor instances. One is
2162 // used to record and process discovered references
2163 // during concurrent marking; the other is used to
2164 // record and process references during STW pauses
2165 // (both full and incremental).
2166 // * Both ref processors need to 'span' the entire heap as
2167 // the regions in the collection set may be dotted around.
2168 //
2169 // * For the concurrent marking ref processor:
2170 // * Reference discovery is enabled at initial marking.
2171 // * Reference discovery is disabled and the discovered
2172 // references processed etc during remarking.
2173 // * Reference discovery is MT (see below).
2174 // * Reference discovery requires a barrier (see below).
2175 // * Reference processing may or may not be MT
2176 // (depending on the value of ParallelRefProcEnabled
2177 // and ParallelGCThreads).
2178 // * A full GC disables reference discovery by the CM
2179 // ref processor and abandons any entries on it's
2180 // discovered lists.
2181 //
2182 // * For the STW processor:
2183 // * Non MT discovery is enabled at the start of a full GC.
2184 // * Processing and enqueueing during a full GC is non-MT.
2185 // * During a full GC, references are processed after marking.
2186 //
2187 // * Discovery (may or may not be MT) is enabled at the start
2188 // of an incremental evacuation pause.
2189 // * References are processed near the end of a STW evacuation pause.
2190 // * For both types of GC:
2191 // * Discovery is atomic - i.e. not concurrent.
2192 // * Reference discovery will not need a barrier.
2193
2194 SharedHeap::ref_processing_init();
2195 MemRegion mr = reserved_region();
2196
2197 // Concurrent Mark ref processor
2198 _ref_processor_cm =
2199 new ReferenceProcessor(mr, // span
2200 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2201 // mt processing
2202 (int) ParallelGCThreads,
2203 // degree of mt processing
2204 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2205 // mt discovery
2206 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2207 // degree of mt discovery
2208 false,
2209 // Reference discovery is not atomic
2210 &_is_alive_closure_cm);
2211 // is alive closure
2212 // (for efficiency/performance)
2213
2214 // STW ref processor
2215 _ref_processor_stw =
2216 new ReferenceProcessor(mr, // span
2217 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2218 // mt processing
2219 MAX2((int)ParallelGCThreads, 1),
2220 // degree of mt processing
2221 (ParallelGCThreads > 1),
2222 // mt discovery
2223 MAX2((int)ParallelGCThreads, 1),
2224 // degree of mt discovery
2225 true,
2226 // Reference discovery is atomic
2227 &_is_alive_closure_stw);
2228 // is alive closure
2229 // (for efficiency/performance)
2230 }
2231
2232 size_t G1CollectedHeap::capacity() const {
2233 return _hrm.length() * HeapRegion::GrainBytes;
2234 }
2235
2236 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2237 assert(!hr->is_continues_humongous(), "pre-condition");
2238 hr->reset_gc_time_stamp();
2239 if (hr->is_starts_humongous()) {
2240 uint first_index = hr->hrm_index() + 1;
2241 uint last_index = hr->last_hc_index();
2242 for (uint i = first_index; i < last_index; i += 1) {
2243 HeapRegion* chr = region_at(i);
2244 assert(chr->is_continues_humongous(), "sanity");
2245 chr->reset_gc_time_stamp();
2246 }
2247 }
2248 }
2249
2250 #ifndef PRODUCT
2251 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2252 private:
2253 unsigned _gc_time_stamp;
2254 bool _failures;
2255
2256 public:
2257 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2258 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2259
2260 virtual bool doHeapRegion(HeapRegion* hr) {
2261 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2262 if (_gc_time_stamp != region_gc_time_stamp) {
2263 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2264 "expected %d", HR_FORMAT_PARAMS(hr),
2265 region_gc_time_stamp, _gc_time_stamp);
2266 _failures = true;
2267 }
2268 return false;
2269 }
2270
2271 bool failures() { return _failures; }
2272 };
2273
2274 void G1CollectedHeap::check_gc_time_stamps() {
2275 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2276 heap_region_iterate(&cl);
2277 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2278 }
2279 #endif // PRODUCT
2280
2281 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2282 DirtyCardQueue* into_cset_dcq,
2283 bool concurrent,
2284 uint worker_i) {
2285 // Clean cards in the hot card cache
2286 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2287 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2288
2289 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2290 int n_completed_buffers = 0;
2291 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2292 n_completed_buffers++;
2293 }
2294 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2295 dcqs.clear_n_completed_buffers();
2296 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2297 }
2298
2299
2300 // Computes the sum of the storage used by the various regions.
2301 size_t G1CollectedHeap::used() const {
2302 return _allocator->used();
2303 }
2304
2305 size_t G1CollectedHeap::used_unlocked() const {
2306 return _allocator->used_unlocked();
2307 }
2308
2309 class SumUsedClosure: public HeapRegionClosure {
2310 size_t _used;
2311 public:
2312 SumUsedClosure() : _used(0) {}
2313 bool doHeapRegion(HeapRegion* r) {
2314 if (!r->is_continues_humongous()) {
2315 _used += r->used();
2316 }
2317 return false;
2318 }
2319 size_t result() { return _used; }
2320 };
2321
2322 size_t G1CollectedHeap::recalculate_used() const {
2323 double recalculate_used_start = os::elapsedTime();
2324
2325 SumUsedClosure blk;
2326 heap_region_iterate(&blk);
2327
2328 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2329 return blk.result();
2330 }
2331
2332 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2333 switch (cause) {
2334 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2335 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2336 case GCCause::_g1_humongous_allocation: return true;
2337 case GCCause::_update_allocation_context_stats_inc: return true;
2338 default: return false;
2339 }
2340 }
2341
2342 #ifndef PRODUCT
2343 void G1CollectedHeap::allocate_dummy_regions() {
2344 // Let's fill up most of the region
2345 size_t word_size = HeapRegion::GrainWords - 1024;
2346 // And as a result the region we'll allocate will be humongous.
2347 guarantee(is_humongous(word_size), "sanity");
2348
2349 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2350 // Let's use the existing mechanism for the allocation
2351 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2352 AllocationContext::system());
2353 if (dummy_obj != NULL) {
2354 MemRegion mr(dummy_obj, word_size);
2355 CollectedHeap::fill_with_object(mr);
2356 } else {
2357 // If we can't allocate once, we probably cannot allocate
2358 // again. Let's get out of the loop.
2359 break;
2360 }
2361 }
2362 }
2363 #endif // !PRODUCT
2364
2365 void G1CollectedHeap::increment_old_marking_cycles_started() {
2366 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2367 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2368 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2369 _old_marking_cycles_started, _old_marking_cycles_completed));
2370
2371 _old_marking_cycles_started++;
2372 }
2373
2374 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2375 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2376
2377 // We assume that if concurrent == true, then the caller is a
2378 // concurrent thread that was joined the Suspendible Thread
2379 // Set. If there's ever a cheap way to check this, we should add an
2380 // assert here.
2381
2382 // Given that this method is called at the end of a Full GC or of a
2383 // concurrent cycle, and those can be nested (i.e., a Full GC can
2384 // interrupt a concurrent cycle), the number of full collections
2385 // completed should be either one (in the case where there was no
2386 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2387 // behind the number of full collections started.
2388
2389 // This is the case for the inner caller, i.e. a Full GC.
2390 assert(concurrent ||
2391 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2392 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2393 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2394 "is inconsistent with _old_marking_cycles_completed = %u",
2395 _old_marking_cycles_started, _old_marking_cycles_completed));
2396
2397 // This is the case for the outer caller, i.e. the concurrent cycle.
2398 assert(!concurrent ||
2399 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2400 err_msg("for outer caller (concurrent cycle): "
2401 "_old_marking_cycles_started = %u "
2402 "is inconsistent with _old_marking_cycles_completed = %u",
2403 _old_marking_cycles_started, _old_marking_cycles_completed));
2404
2405 _old_marking_cycles_completed += 1;
2406
2407 // We need to clear the "in_progress" flag in the CM thread before
2408 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2409 // is set) so that if a waiter requests another System.gc() it doesn't
2410 // incorrectly see that a marking cycle is still in progress.
2411 if (concurrent) {
2412 _cmThread->clear_in_progress();
2413 }
2414
2415 // This notify_all() will ensure that a thread that called
2416 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2417 // and it's waiting for a full GC to finish will be woken up. It is
2418 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2419 FullGCCount_lock->notify_all();
2420 }
2421
2422 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2423 _concurrent_cycle_started = true;
2424 _gc_timer_cm->register_gc_start(start_time);
2425
2426 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2427 trace_heap_before_gc(_gc_tracer_cm);
2428 }
2429
2430 void G1CollectedHeap::register_concurrent_cycle_end() {
2431 if (_concurrent_cycle_started) {
2432 if (_cm->has_aborted()) {
2433 _gc_tracer_cm->report_concurrent_mode_failure();
2434 }
2435
2436 _gc_timer_cm->register_gc_end();
2437 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2438
2439 // Clear state variables to prepare for the next concurrent cycle.
2440 _concurrent_cycle_started = false;
2441 _heap_summary_sent = false;
2442 }
2443 }
2444
2445 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2446 if (_concurrent_cycle_started) {
2447 // This function can be called when:
2448 // the cleanup pause is run
2449 // the concurrent cycle is aborted before the cleanup pause.
2450 // the concurrent cycle is aborted after the cleanup pause,
2451 // but before the concurrent cycle end has been registered.
2452 // Make sure that we only send the heap information once.
2453 if (!_heap_summary_sent) {
2454 trace_heap_after_gc(_gc_tracer_cm);
2455 _heap_summary_sent = true;
2456 }
2457 }
2458 }
2459
2460 G1YCType G1CollectedHeap::yc_type() {
2461 bool is_young = g1_policy()->gcs_are_young();
2462 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2463 bool is_during_mark = mark_in_progress();
2464
2465 if (is_initial_mark) {
2466 return InitialMark;
2467 } else if (is_during_mark) {
2468 return DuringMark;
2469 } else if (is_young) {
2470 return Normal;
2471 } else {
2472 return Mixed;
2473 }
2474 }
2475
2476 void G1CollectedHeap::collect(GCCause::Cause cause) {
2477 assert_heap_not_locked();
2478
2479 unsigned int gc_count_before;
2480 unsigned int old_marking_count_before;
2481 unsigned int full_gc_count_before;
2482 bool retry_gc;
2483
2484 do {
2485 retry_gc = false;
2486
2487 {
2488 MutexLocker ml(Heap_lock);
2489
2490 // Read the GC count while holding the Heap_lock
2491 gc_count_before = total_collections();
2492 full_gc_count_before = total_full_collections();
2493 old_marking_count_before = _old_marking_cycles_started;
2494 }
2495
2496 if (should_do_concurrent_full_gc(cause)) {
2497 // Schedule an initial-mark evacuation pause that will start a
2498 // concurrent cycle. We're setting word_size to 0 which means that
2499 // we are not requesting a post-GC allocation.
2500 VM_G1IncCollectionPause op(gc_count_before,
2501 0, /* word_size */
2502 true, /* should_initiate_conc_mark */
2503 g1_policy()->max_pause_time_ms(),
2504 cause);
2505 op.set_allocation_context(AllocationContext::current());
2506
2507 VMThread::execute(&op);
2508 if (!op.pause_succeeded()) {
2509 if (old_marking_count_before == _old_marking_cycles_started) {
2510 retry_gc = op.should_retry_gc();
2511 } else {
2512 // A Full GC happened while we were trying to schedule the
2513 // initial-mark GC. No point in starting a new cycle given
2514 // that the whole heap was collected anyway.
2515 }
2516
2517 if (retry_gc) {
2518 if (GC_locker::is_active_and_needs_gc()) {
2519 GC_locker::stall_until_clear();
2520 }
2521 }
2522 }
2523 } else {
2524 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2525 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2526
2527 // Schedule a standard evacuation pause. We're setting word_size
2528 // to 0 which means that we are not requesting a post-GC allocation.
2529 VM_G1IncCollectionPause op(gc_count_before,
2530 0, /* word_size */
2531 false, /* should_initiate_conc_mark */
2532 g1_policy()->max_pause_time_ms(),
2533 cause);
2534 VMThread::execute(&op);
2535 } else {
2536 // Schedule a Full GC.
2537 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2538 VMThread::execute(&op);
2539 }
2540 }
2541 } while (retry_gc);
2542 }
2543
2544 bool G1CollectedHeap::is_in(const void* p) const {
2545 if (_hrm.reserved().contains(p)) {
2546 // Given that we know that p is in the reserved space,
2547 // heap_region_containing_raw() should successfully
2548 // return the containing region.
2549 HeapRegion* hr = heap_region_containing_raw(p);
2550 return hr->is_in(p);
2551 } else {
2552 return false;
2553 }
2554 }
2555
2556 #ifdef ASSERT
2557 bool G1CollectedHeap::is_in_exact(const void* p) const {
2558 bool contains = reserved_region().contains(p);
2559 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2560 if (contains && available) {
2561 return true;
2562 } else {
2563 return false;
2564 }
2565 }
2566 #endif
2567
2568 // Iteration functions.
2569
2570 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2571
2572 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2573 ExtendedOopClosure* _cl;
2574 public:
2575 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2576 bool doHeapRegion(HeapRegion* r) {
2577 if (!r->is_continues_humongous()) {
2578 r->oop_iterate(_cl);
2579 }
2580 return false;
2581 }
2582 };
2583
2584 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2585 IterateOopClosureRegionClosure blk(cl);
2586 heap_region_iterate(&blk);
2587 }
2588
2589 // Iterates an ObjectClosure over all objects within a HeapRegion.
2590
2591 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2592 ObjectClosure* _cl;
2593 public:
2594 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2595 bool doHeapRegion(HeapRegion* r) {
2596 if (!r->is_continues_humongous()) {
2597 r->object_iterate(_cl);
2598 }
2599 return false;
2600 }
2601 };
2602
2603 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2604 IterateObjectClosureRegionClosure blk(cl);
2605 heap_region_iterate(&blk);
2606 }
2607
2608 // Calls a SpaceClosure on a HeapRegion.
2609
2610 class SpaceClosureRegionClosure: public HeapRegionClosure {
2611 SpaceClosure* _cl;
2612 public:
2613 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2614 bool doHeapRegion(HeapRegion* r) {
2615 _cl->do_space(r);
2616 return false;
2617 }
2618 };
2619
2620 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2621 SpaceClosureRegionClosure blk(cl);
2622 heap_region_iterate(&blk);
2623 }
2624
2625 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2626 _hrm.iterate(cl);
2627 }
2628
2629 void
2630 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2631 uint worker_id,
2632 HeapRegionClaimer *hrclaimer) const {
2633 _hrm.par_iterate(cl, worker_id, hrclaimer);
2634 }
2635
2636 // Clear the cached CSet starting regions and (more importantly)
2637 // the time stamps. Called when we reset the GC time stamp.
2638 void G1CollectedHeap::clear_cset_start_regions() {
2639 assert(_worker_cset_start_region != NULL, "sanity");
2640 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2641
2642 int n_queues = MAX2((int)ParallelGCThreads, 1);
2643 for (int i = 0; i < n_queues; i++) {
2644 _worker_cset_start_region[i] = NULL;
2645 _worker_cset_start_region_time_stamp[i] = 0;
2646 }
2647 }
2648
2649 // Given the id of a worker, obtain or calculate a suitable
2650 // starting region for iterating over the current collection set.
2651 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2652 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2653
2654 HeapRegion* result = NULL;
2655 unsigned gc_time_stamp = get_gc_time_stamp();
2656
2657 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2658 // Cached starting region for current worker was set
2659 // during the current pause - so it's valid.
2660 // Note: the cached starting heap region may be NULL
2661 // (when the collection set is empty).
2662 result = _worker_cset_start_region[worker_i];
2663 assert(result == NULL || result->in_collection_set(), "sanity");
2664 return result;
2665 }
2666
2667 // The cached entry was not valid so let's calculate
2668 // a suitable starting heap region for this worker.
2669
2670 // We want the parallel threads to start their collection
2671 // set iteration at different collection set regions to
2672 // avoid contention.
2673 // If we have:
2674 // n collection set regions
2675 // p threads
2676 // Then thread t will start at region floor ((t * n) / p)
2677
2678 result = g1_policy()->collection_set();
2679 uint cs_size = g1_policy()->cset_region_length();
2680 uint active_workers = workers()->active_workers();
2681 assert(UseDynamicNumberOfGCThreads ||
2682 active_workers == workers()->total_workers(),
2683 "Unless dynamic should use total workers");
2684
2685 uint end_ind = (cs_size * worker_i) / active_workers;
2686 uint start_ind = 0;
2687
2688 if (worker_i > 0 &&
2689 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2690 // Previous workers starting region is valid
2691 // so let's iterate from there
2692 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2693 result = _worker_cset_start_region[worker_i - 1];
2694 }
2695
2696 for (uint i = start_ind; i < end_ind; i++) {
2697 result = result->next_in_collection_set();
2698 }
2699
2700 // Note: the calculated starting heap region may be NULL
2701 // (when the collection set is empty).
2702 assert(result == NULL || result->in_collection_set(), "sanity");
2703 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2704 "should be updated only once per pause");
2705 _worker_cset_start_region[worker_i] = result;
2706 OrderAccess::storestore();
2707 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2708 return result;
2709 }
2710
2711 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2712 HeapRegion* r = g1_policy()->collection_set();
2713 while (r != NULL) {
2714 HeapRegion* next = r->next_in_collection_set();
2715 if (cl->doHeapRegion(r)) {
2716 cl->incomplete();
2717 return;
2718 }
2719 r = next;
2720 }
2721 }
2722
2723 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2724 HeapRegionClosure *cl) {
2725 if (r == NULL) {
2726 // The CSet is empty so there's nothing to do.
2727 return;
2728 }
2729
2730 assert(r->in_collection_set(),
2731 "Start region must be a member of the collection set.");
2732 HeapRegion* cur = r;
2733 while (cur != NULL) {
2734 HeapRegion* next = cur->next_in_collection_set();
2735 if (cl->doHeapRegion(cur) && false) {
2736 cl->incomplete();
2737 return;
2738 }
2739 cur = next;
2740 }
2741 cur = g1_policy()->collection_set();
2742 while (cur != r) {
2743 HeapRegion* next = cur->next_in_collection_set();
2744 if (cl->doHeapRegion(cur) && false) {
2745 cl->incomplete();
2746 return;
2747 }
2748 cur = next;
2749 }
2750 }
2751
2752 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2753 HeapRegion* result = _hrm.next_region_in_heap(from);
2754 while (result != NULL && result->is_humongous()) {
2755 result = _hrm.next_region_in_heap(result);
2756 }
2757 return result;
2758 }
2759
2760 Space* G1CollectedHeap::space_containing(const void* addr) const {
2761 return heap_region_containing(addr);
2762 }
2763
2764 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2765 Space* sp = space_containing(addr);
2766 return sp->block_start(addr);
2767 }
2768
2769 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2770 Space* sp = space_containing(addr);
2771 return sp->block_size(addr);
2772 }
2773
2774 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2775 Space* sp = space_containing(addr);
2776 return sp->block_is_obj(addr);
2777 }
2778
2779 bool G1CollectedHeap::supports_tlab_allocation() const {
2780 return true;
2781 }
2782
2783 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2784 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2785 }
2786
2787 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2788 return young_list()->eden_used_bytes();
2789 }
2790
2791 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2792 // must be smaller than the humongous object limit.
2793 size_t G1CollectedHeap::max_tlab_size() const {
2794 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2795 }
2796
2797 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2798 // Return the remaining space in the cur alloc region, but not less than
2799 // the min TLAB size.
2800
2801 // Also, this value can be at most the humongous object threshold,
2802 // since we can't allow tlabs to grow big enough to accommodate
2803 // humongous objects.
2804
2805 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2806 size_t max_tlab = max_tlab_size() * wordSize;
2807 if (hr == NULL) {
2808 return max_tlab;
2809 } else {
2810 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2811 }
2812 }
2813
2814 size_t G1CollectedHeap::max_capacity() const {
2815 return _hrm.reserved().byte_size();
2816 }
2817
2818 jlong G1CollectedHeap::millis_since_last_gc() {
2819 // assert(false, "NYI");
2820 return 0;
2821 }
2822
2823 void G1CollectedHeap::prepare_for_verify() {
2824 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2825 ensure_parsability(false);
2826 }
2827 g1_rem_set()->prepare_for_verify();
2828 }
2829
2830 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2831 VerifyOption vo) {
2832 switch (vo) {
2833 case VerifyOption_G1UsePrevMarking:
2834 return hr->obj_allocated_since_prev_marking(obj);
2835 case VerifyOption_G1UseNextMarking:
2836 return hr->obj_allocated_since_next_marking(obj);
2837 case VerifyOption_G1UseMarkWord:
2838 return false;
2839 default:
2840 ShouldNotReachHere();
2841 }
2842 return false; // keep some compilers happy
2843 }
2844
2845 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2846 switch (vo) {
2847 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2848 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2849 case VerifyOption_G1UseMarkWord: return NULL;
2850 default: ShouldNotReachHere();
2851 }
2852 return NULL; // keep some compilers happy
2853 }
2854
2855 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2856 switch (vo) {
2857 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2858 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2859 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2860 default: ShouldNotReachHere();
2861 }
2862 return false; // keep some compilers happy
2863 }
2864
2865 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2866 switch (vo) {
2867 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2868 case VerifyOption_G1UseNextMarking: return "NTAMS";
2869 case VerifyOption_G1UseMarkWord: return "NONE";
2870 default: ShouldNotReachHere();
2871 }
2872 return NULL; // keep some compilers happy
2873 }
2874
2875 class VerifyRootsClosure: public OopClosure {
2876 private:
2877 G1CollectedHeap* _g1h;
2878 VerifyOption _vo;
2879 bool _failures;
2880 public:
2881 // _vo == UsePrevMarking -> use "prev" marking information,
2882 // _vo == UseNextMarking -> use "next" marking information,
2883 // _vo == UseMarkWord -> use mark word from object header.
2884 VerifyRootsClosure(VerifyOption vo) :
2885 _g1h(G1CollectedHeap::heap()),
2886 _vo(vo),
2887 _failures(false) { }
2888
2889 bool failures() { return _failures; }
2890
2891 template <class T> void do_oop_nv(T* p) {
2892 T heap_oop = oopDesc::load_heap_oop(p);
2893 if (!oopDesc::is_null(heap_oop)) {
2894 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2895 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2896 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2897 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2898 if (_vo == VerifyOption_G1UseMarkWord) {
2899 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2900 }
2901 obj->print_on(gclog_or_tty);
2902 _failures = true;
2903 }
2904 }
2905 }
2906
2907 void do_oop(oop* p) { do_oop_nv(p); }
2908 void do_oop(narrowOop* p) { do_oop_nv(p); }
2909 };
2910
2911 class G1VerifyCodeRootOopClosure: public OopClosure {
2912 G1CollectedHeap* _g1h;
2913 OopClosure* _root_cl;
2914 nmethod* _nm;
2915 VerifyOption _vo;
2916 bool _failures;
2917
2918 template <class T> void do_oop_work(T* p) {
2919 // First verify that this root is live
2920 _root_cl->do_oop(p);
2921
2922 if (!G1VerifyHeapRegionCodeRoots) {
2923 // We're not verifying the code roots attached to heap region.
2924 return;
2925 }
2926
2927 // Don't check the code roots during marking verification in a full GC
2928 if (_vo == VerifyOption_G1UseMarkWord) {
2929 return;
2930 }
2931
2932 // Now verify that the current nmethod (which contains p) is
2933 // in the code root list of the heap region containing the
2934 // object referenced by p.
2935
2936 T heap_oop = oopDesc::load_heap_oop(p);
2937 if (!oopDesc::is_null(heap_oop)) {
2938 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2939
2940 // Now fetch the region containing the object
2941 HeapRegion* hr = _g1h->heap_region_containing(obj);
2942 HeapRegionRemSet* hrrs = hr->rem_set();
2943 // Verify that the strong code root list for this region
2944 // contains the nmethod
2945 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2946 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2947 "from nmethod "PTR_FORMAT" not in strong "
2948 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2949 p, _nm, hr->bottom(), hr->end());
2950 _failures = true;
2951 }
2952 }
2953 }
2954
2955 public:
2956 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2957 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2958
2959 void do_oop(oop* p) { do_oop_work(p); }
2960 void do_oop(narrowOop* p) { do_oop_work(p); }
2961
2962 void set_nmethod(nmethod* nm) { _nm = nm; }
2963 bool failures() { return _failures; }
2964 };
2965
2966 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2967 G1VerifyCodeRootOopClosure* _oop_cl;
2968
2969 public:
2970 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2971 _oop_cl(oop_cl) {}
2972
2973 void do_code_blob(CodeBlob* cb) {
2974 nmethod* nm = cb->as_nmethod_or_null();
2975 if (nm != NULL) {
2976 _oop_cl->set_nmethod(nm);
2977 nm->oops_do(_oop_cl);
2978 }
2979 }
2980 };
2981
2982 class YoungRefCounterClosure : public OopClosure {
2983 G1CollectedHeap* _g1h;
2984 int _count;
2985 public:
2986 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2987 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2988 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2989
2990 int count() { return _count; }
2991 void reset_count() { _count = 0; };
2992 };
2993
2994 class VerifyKlassClosure: public KlassClosure {
2995 YoungRefCounterClosure _young_ref_counter_closure;
2996 OopClosure *_oop_closure;
2997 public:
2998 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2999 void do_klass(Klass* k) {
3000 k->oops_do(_oop_closure);
3001
3002 _young_ref_counter_closure.reset_count();
3003 k->oops_do(&_young_ref_counter_closure);
3004 if (_young_ref_counter_closure.count() > 0) {
3005 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3006 }
3007 }
3008 };
3009
3010 class VerifyLivenessOopClosure: public OopClosure {
3011 G1CollectedHeap* _g1h;
3012 VerifyOption _vo;
3013 public:
3014 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3015 _g1h(g1h), _vo(vo)
3016 { }
3017 void do_oop(narrowOop *p) { do_oop_work(p); }
3018 void do_oop( oop *p) { do_oop_work(p); }
3019
3020 template <class T> void do_oop_work(T *p) {
3021 oop obj = oopDesc::load_decode_heap_oop(p);
3022 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3023 "Dead object referenced by a not dead object");
3024 }
3025 };
3026
3027 class VerifyObjsInRegionClosure: public ObjectClosure {
3028 private:
3029 G1CollectedHeap* _g1h;
3030 size_t _live_bytes;
3031 HeapRegion *_hr;
3032 VerifyOption _vo;
3033 public:
3034 // _vo == UsePrevMarking -> use "prev" marking information,
3035 // _vo == UseNextMarking -> use "next" marking information,
3036 // _vo == UseMarkWord -> use mark word from object header.
3037 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3038 : _live_bytes(0), _hr(hr), _vo(vo) {
3039 _g1h = G1CollectedHeap::heap();
3040 }
3041 void do_object(oop o) {
3042 VerifyLivenessOopClosure isLive(_g1h, _vo);
3043 assert(o != NULL, "Huh?");
3044 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3045 // If the object is alive according to the mark word,
3046 // then verify that the marking information agrees.
3047 // Note we can't verify the contra-positive of the
3048 // above: if the object is dead (according to the mark
3049 // word), it may not be marked, or may have been marked
3050 // but has since became dead, or may have been allocated
3051 // since the last marking.
3052 if (_vo == VerifyOption_G1UseMarkWord) {
3053 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3054 }
3055
3056 o->oop_iterate_no_header(&isLive);
3057 if (!_hr->obj_allocated_since_prev_marking(o)) {
3058 size_t obj_size = o->size(); // Make sure we don't overflow
3059 _live_bytes += (obj_size * HeapWordSize);
3060 }
3061 }
3062 }
3063 size_t live_bytes() { return _live_bytes; }
3064 };
3065
3066 class PrintObjsInRegionClosure : public ObjectClosure {
3067 HeapRegion *_hr;
3068 G1CollectedHeap *_g1;
3069 public:
3070 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3071 _g1 = G1CollectedHeap::heap();
3072 };
3073
3074 void do_object(oop o) {
3075 if (o != NULL) {
3076 HeapWord *start = (HeapWord *) o;
3077 size_t word_sz = o->size();
3078 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3079 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3080 (void*) o, word_sz,
3081 _g1->isMarkedPrev(o),
3082 _g1->isMarkedNext(o),
3083 _hr->obj_allocated_since_prev_marking(o));
3084 HeapWord *end = start + word_sz;
3085 HeapWord *cur;
3086 int *val;
3087 for (cur = start; cur < end; cur++) {
3088 val = (int *) cur;
3089 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3090 }
3091 }
3092 }
3093 };
3094
3095 class VerifyRegionClosure: public HeapRegionClosure {
3096 private:
3097 bool _par;
3098 VerifyOption _vo;
3099 bool _failures;
3100 public:
3101 // _vo == UsePrevMarking -> use "prev" marking information,
3102 // _vo == UseNextMarking -> use "next" marking information,
3103 // _vo == UseMarkWord -> use mark word from object header.
3104 VerifyRegionClosure(bool par, VerifyOption vo)
3105 : _par(par),
3106 _vo(vo),
3107 _failures(false) {}
3108
3109 bool failures() {
3110 return _failures;
3111 }
3112
3113 bool doHeapRegion(HeapRegion* r) {
3114 if (!r->is_continues_humongous()) {
3115 bool failures = false;
3116 r->verify(_vo, &failures);
3117 if (failures) {
3118 _failures = true;
3119 } else {
3120 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3121 r->object_iterate(¬_dead_yet_cl);
3122 if (_vo != VerifyOption_G1UseNextMarking) {
3123 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3124 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3125 "max_live_bytes "SIZE_FORMAT" "
3126 "< calculated "SIZE_FORMAT,
3127 r->bottom(), r->end(),
3128 r->max_live_bytes(),
3129 not_dead_yet_cl.live_bytes());
3130 _failures = true;
3131 }
3132 } else {
3133 // When vo == UseNextMarking we cannot currently do a sanity
3134 // check on the live bytes as the calculation has not been
3135 // finalized yet.
3136 }
3137 }
3138 }
3139 return false; // stop the region iteration if we hit a failure
3140 }
3141 };
3142
3143 // This is the task used for parallel verification of the heap regions
3144
3145 class G1ParVerifyTask: public AbstractGangTask {
3146 private:
3147 G1CollectedHeap* _g1h;
3148 VerifyOption _vo;
3149 bool _failures;
3150 HeapRegionClaimer _hrclaimer;
3151
3152 public:
3153 // _vo == UsePrevMarking -> use "prev" marking information,
3154 // _vo == UseNextMarking -> use "next" marking information,
3155 // _vo == UseMarkWord -> use mark word from object header.
3156 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3157 AbstractGangTask("Parallel verify task"),
3158 _g1h(g1h),
3159 _vo(vo),
3160 _failures(false),
3161 _hrclaimer(g1h->workers()->active_workers()) {}
3162
3163 bool failures() {
3164 return _failures;
3165 }
3166
3167 void work(uint worker_id) {
3168 HandleMark hm;
3169 VerifyRegionClosure blk(true, _vo);
3170 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3171 if (blk.failures()) {
3172 _failures = true;
3173 }
3174 }
3175 };
3176
3177 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3178 if (SafepointSynchronize::is_at_safepoint()) {
3179 assert(Thread::current()->is_VM_thread(),
3180 "Expected to be executed serially by the VM thread at this point");
3181
3182 if (!silent) { gclog_or_tty->print("Roots "); }
3183 VerifyRootsClosure rootsCl(vo);
3184 VerifyKlassClosure klassCl(this, &rootsCl);
3185 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3186
3187 // We apply the relevant closures to all the oops in the
3188 // system dictionary, class loader data graph, the string table
3189 // and the nmethods in the code cache.
3190 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3191 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3192
3193 process_all_roots(true, // activate StrongRootsScope
3194 SO_AllCodeCache, // roots scanning options
3195 &rootsCl,
3196 &cldCl,
3197 &blobsCl);
3198
3199 bool failures = rootsCl.failures() || codeRootsCl.failures();
3200
3201 if (vo != VerifyOption_G1UseMarkWord) {
3202 // If we're verifying during a full GC then the region sets
3203 // will have been torn down at the start of the GC. Therefore
3204 // verifying the region sets will fail. So we only verify
3205 // the region sets when not in a full GC.
3206 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3207 verify_region_sets();
3208 }
3209
3210 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3211 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3212
3213 G1ParVerifyTask task(this, vo);
3214 assert(UseDynamicNumberOfGCThreads ||
3215 workers()->active_workers() == workers()->total_workers(),
3216 "If not dynamic should be using all the workers");
3217 int n_workers = workers()->active_workers();
3218 set_par_threads(n_workers);
3219 workers()->run_task(&task);
3220 set_par_threads(0);
3221 if (task.failures()) {
3222 failures = true;
3223 }
3224
3225 } else {
3226 VerifyRegionClosure blk(false, vo);
3227 heap_region_iterate(&blk);
3228 if (blk.failures()) {
3229 failures = true;
3230 }
3231 }
3232 if (!silent) gclog_or_tty->print("RemSet ");
3233 rem_set()->verify();
3234
3235 if (G1StringDedup::is_enabled()) {
3236 if (!silent) gclog_or_tty->print("StrDedup ");
3237 G1StringDedup::verify();
3238 }
3239
3240 if (failures) {
3241 gclog_or_tty->print_cr("Heap:");
3242 // It helps to have the per-region information in the output to
3243 // help us track down what went wrong. This is why we call
3244 // print_extended_on() instead of print_on().
3245 print_extended_on(gclog_or_tty);
3246 gclog_or_tty->cr();
3247 #ifndef PRODUCT
3248 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3249 concurrent_mark()->print_reachable("at-verification-failure",
3250 vo, false /* all */);
3251 }
3252 #endif
3253 gclog_or_tty->flush();
3254 }
3255 guarantee(!failures, "there should not have been any failures");
3256 } else {
3257 if (!silent) {
3258 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3259 if (G1StringDedup::is_enabled()) {
3260 gclog_or_tty->print(", StrDedup");
3261 }
3262 gclog_or_tty->print(") ");
3263 }
3264 }
3265 }
3266
3267 void G1CollectedHeap::verify(bool silent) {
3268 verify(silent, VerifyOption_G1UsePrevMarking);
3269 }
3270
3271 double G1CollectedHeap::verify(bool guard, const char* msg) {
3272 double verify_time_ms = 0.0;
3273
3274 if (guard && total_collections() >= VerifyGCStartAt) {
3275 double verify_start = os::elapsedTime();
3276 HandleMark hm; // Discard invalid handles created during verification
3277 prepare_for_verify();
3278 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3279 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3280 }
3281
3282 return verify_time_ms;
3283 }
3284
3285 void G1CollectedHeap::verify_before_gc() {
3286 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3287 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3288 }
3289
3290 void G1CollectedHeap::verify_after_gc() {
3291 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3292 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3293 }
3294
3295 class PrintRegionClosure: public HeapRegionClosure {
3296 outputStream* _st;
3297 public:
3298 PrintRegionClosure(outputStream* st) : _st(st) {}
3299 bool doHeapRegion(HeapRegion* r) {
3300 r->print_on(_st);
3301 return false;
3302 }
3303 };
3304
3305 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3306 const HeapRegion* hr,
3307 const VerifyOption vo) const {
3308 switch (vo) {
3309 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3310 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3311 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3312 default: ShouldNotReachHere();
3313 }
3314 return false; // keep some compilers happy
3315 }
3316
3317 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3318 const VerifyOption vo) const {
3319 switch (vo) {
3320 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3321 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3322 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3323 default: ShouldNotReachHere();
3324 }
3325 return false; // keep some compilers happy
3326 }
3327
3328 void G1CollectedHeap::print_on(outputStream* st) const {
3329 st->print(" %-20s", "garbage-first heap");
3330 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3331 capacity()/K, used_unlocked()/K);
3332 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3333 _hrm.reserved().start(),
3334 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3335 _hrm.reserved().end());
3336 st->cr();
3337 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3338 uint young_regions = _young_list->length();
3339 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3340 (size_t) young_regions * HeapRegion::GrainBytes / K);
3341 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3342 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3343 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3344 st->cr();
3345 MetaspaceAux::print_on(st);
3346 }
3347
3348 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3349 print_on(st);
3350
3351 // Print the per-region information.
3352 st->cr();
3353 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3354 "HS=humongous(starts), HC=humongous(continues), "
3355 "CS=collection set, F=free, TS=gc time stamp, "
3356 "PTAMS=previous top-at-mark-start, "
3357 "NTAMS=next top-at-mark-start)");
3358 PrintRegionClosure blk(st);
3359 heap_region_iterate(&blk);
3360 }
3361
3362 void G1CollectedHeap::print_on_error(outputStream* st) const {
3363 this->CollectedHeap::print_on_error(st);
3364
3365 if (_cm != NULL) {
3366 st->cr();
3367 _cm->print_on_error(st);
3368 }
3369 }
3370
3371 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3372 workers()->print_worker_threads_on(st);
3373 _cmThread->print_on(st);
3374 st->cr();
3375 _cm->print_worker_threads_on(st);
3376 _cg1r->print_worker_threads_on(st);
3377 if (G1StringDedup::is_enabled()) {
3378 G1StringDedup::print_worker_threads_on(st);
3379 }
3380 }
3381
3382 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3383 workers()->threads_do(tc);
3384 tc->do_thread(_cmThread);
3385 _cg1r->threads_do(tc);
3386 if (G1StringDedup::is_enabled()) {
3387 G1StringDedup::threads_do(tc);
3388 }
3389 }
3390
3391 void G1CollectedHeap::print_tracing_info() const {
3392 // We'll overload this to mean "trace GC pause statistics."
3393 if (TraceYoungGenTime || TraceOldGenTime) {
3394 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3395 // to that.
3396 g1_policy()->print_tracing_info();
3397 }
3398 if (G1SummarizeRSetStats) {
3399 g1_rem_set()->print_summary_info();
3400 }
3401 if (G1SummarizeConcMark) {
3402 concurrent_mark()->print_summary_info();
3403 }
3404 g1_policy()->print_yg_surv_rate_info();
3405 SpecializationStats::print();
3406 }
3407
3408 #ifndef PRODUCT
3409 // Helpful for debugging RSet issues.
3410
3411 class PrintRSetsClosure : public HeapRegionClosure {
3412 private:
3413 const char* _msg;
3414 size_t _occupied_sum;
3415
3416 public:
3417 bool doHeapRegion(HeapRegion* r) {
3418 HeapRegionRemSet* hrrs = r->rem_set();
3419 size_t occupied = hrrs->occupied();
3420 _occupied_sum += occupied;
3421
3422 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3423 HR_FORMAT_PARAMS(r));
3424 if (occupied == 0) {
3425 gclog_or_tty->print_cr(" RSet is empty");
3426 } else {
3427 hrrs->print();
3428 }
3429 gclog_or_tty->print_cr("----------");
3430 return false;
3431 }
3432
3433 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3434 gclog_or_tty->cr();
3435 gclog_or_tty->print_cr("========================================");
3436 gclog_or_tty->print_cr("%s", msg);
3437 gclog_or_tty->cr();
3438 }
3439
3440 ~PrintRSetsClosure() {
3441 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3442 gclog_or_tty->print_cr("========================================");
3443 gclog_or_tty->cr();
3444 }
3445 };
3446
3447 void G1CollectedHeap::print_cset_rsets() {
3448 PrintRSetsClosure cl("Printing CSet RSets");
3449 collection_set_iterate(&cl);
3450 }
3451
3452 void G1CollectedHeap::print_all_rsets() {
3453 PrintRSetsClosure cl("Printing All RSets");;
3454 heap_region_iterate(&cl);
3455 }
3456 #endif // PRODUCT
3457
3458 G1CollectedHeap* G1CollectedHeap::heap() {
3459 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3460 "not a garbage-first heap");
3461 return _g1h;
3462 }
3463
3464 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3465 // always_do_update_barrier = false;
3466 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3467 // Fill TLAB's and such
3468 accumulate_statistics_all_tlabs();
3469 ensure_parsability(true);
3470
3471 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3472 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3473 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3474 }
3475 }
3476
3477 void G1CollectedHeap::gc_epilogue(bool full) {
3478
3479 if (G1SummarizeRSetStats &&
3480 (G1SummarizeRSetStatsPeriod > 0) &&
3481 // we are at the end of the GC. Total collections has already been increased.
3482 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3483 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3484 }
3485
3486 // FIXME: what is this about?
3487 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3488 // is set.
3489 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3490 "derived pointer present"));
3491 // always_do_update_barrier = true;
3492
3493 resize_all_tlabs();
3494 allocation_context_stats().update(full);
3495
3496 // We have just completed a GC. Update the soft reference
3497 // policy with the new heap occupancy
3498 Universe::update_heap_info_at_gc();
3499 }
3500
3501 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3502 unsigned int gc_count_before,
3503 bool* succeeded,
3504 GCCause::Cause gc_cause) {
3505 assert_heap_not_locked_and_not_at_safepoint();
3506 g1_policy()->record_stop_world_start();
3507 VM_G1IncCollectionPause op(gc_count_before,
3508 word_size,
3509 false, /* should_initiate_conc_mark */
3510 g1_policy()->max_pause_time_ms(),
3511 gc_cause);
3512
3513 op.set_allocation_context(AllocationContext::current());
3514 VMThread::execute(&op);
3515
3516 HeapWord* result = op.result();
3517 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3518 assert(result == NULL || ret_succeeded,
3519 "the result should be NULL if the VM did not succeed");
3520 *succeeded = ret_succeeded;
3521
3522 assert_heap_not_locked();
3523 return result;
3524 }
3525
3526 void
3527 G1CollectedHeap::doConcurrentMark() {
3528 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3529 if (!_cmThread->in_progress()) {
3530 _cmThread->set_started();
3531 CGC_lock->notify();
3532 }
3533 }
3534
3535 size_t G1CollectedHeap::pending_card_num() {
3536 size_t extra_cards = 0;
3537 JavaThread *curr = Threads::first();
3538 while (curr != NULL) {
3539 DirtyCardQueue& dcq = curr->dirty_card_queue();
3540 extra_cards += dcq.size();
3541 curr = curr->next();
3542 }
3543 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3544 size_t buffer_size = dcqs.buffer_size();
3545 size_t buffer_num = dcqs.completed_buffers_num();
3546
3547 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3548 // in bytes - not the number of 'entries'. We need to convert
3549 // into a number of cards.
3550 return (buffer_size * buffer_num + extra_cards) / oopSize;
3551 }
3552
3553 size_t G1CollectedHeap::cards_scanned() {
3554 return g1_rem_set()->cardsScanned();
3555 }
3556
3557 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3558 HeapRegion* region = region_at(index);
3559 assert(region->is_starts_humongous(), "Must start a humongous object");
3560 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3561 }
3562
3563 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3564 private:
3565 size_t _total_humongous;
3566 size_t _candidate_humongous;
3567 public:
3568 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3569 }
3570
3571 virtual bool doHeapRegion(HeapRegion* r) {
3572 if (!r->is_starts_humongous()) {
3573 return false;
3574 }
3575 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3576
3577 uint region_idx = r->hrm_index();
3578 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3579 // Is_candidate already filters out humongous regions with some remembered set.
3580 // This will not lead to humongous object that we mistakenly keep alive because
3581 // during young collection the remembered sets will only be added to.
3582 if (is_candidate) {
3583 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3584 _candidate_humongous++;
3585 }
3586 _total_humongous++;
3587
3588 return false;
3589 }
3590
3591 size_t total_humongous() const { return _total_humongous; }
3592 size_t candidate_humongous() const { return _candidate_humongous; }
3593 };
3594
3595 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3596 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3597 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3598 return;
3599 }
3600
3601 RegisterHumongousWithInCSetFastTestClosure cl;
3602 heap_region_iterate(&cl);
3603 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3604 cl.candidate_humongous());
3605 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3606
3607 if (_has_humongous_reclaim_candidates || G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
3608 clear_humongous_is_live_table();
3609 }
3610 }
3611
3612 void
3613 G1CollectedHeap::setup_surviving_young_words() {
3614 assert(_surviving_young_words == NULL, "pre-condition");
3615 uint array_length = g1_policy()->young_cset_region_length();
3616 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3617 if (_surviving_young_words == NULL) {
3618 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3619 "Not enough space for young surv words summary.");
3620 }
3621 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3622 #ifdef ASSERT
3623 for (uint i = 0; i < array_length; ++i) {
3624 assert( _surviving_young_words[i] == 0, "memset above" );
3625 }
3626 #endif // !ASSERT
3627 }
3628
3629 void
3630 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3631 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3632 uint array_length = g1_policy()->young_cset_region_length();
3633 for (uint i = 0; i < array_length; ++i) {
3634 _surviving_young_words[i] += surv_young_words[i];
3635 }
3636 }
3637
3638 void
3639 G1CollectedHeap::cleanup_surviving_young_words() {
3640 guarantee( _surviving_young_words != NULL, "pre-condition" );
3641 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3642 _surviving_young_words = NULL;
3643 }
3644
3645 #ifdef ASSERT
3646 class VerifyCSetClosure: public HeapRegionClosure {
3647 public:
3648 bool doHeapRegion(HeapRegion* hr) {
3649 // Here we check that the CSet region's RSet is ready for parallel
3650 // iteration. The fields that we'll verify are only manipulated
3651 // when the region is part of a CSet and is collected. Afterwards,
3652 // we reset these fields when we clear the region's RSet (when the
3653 // region is freed) so they are ready when the region is
3654 // re-allocated. The only exception to this is if there's an
3655 // evacuation failure and instead of freeing the region we leave
3656 // it in the heap. In that case, we reset these fields during
3657 // evacuation failure handling.
3658 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3659
3660 // Here's a good place to add any other checks we'd like to
3661 // perform on CSet regions.
3662 return false;
3663 }
3664 };
3665 #endif // ASSERT
3666
3667 #if TASKQUEUE_STATS
3668 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3669 st->print_raw_cr("GC Task Stats");
3670 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3671 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3672 }
3673
3674 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3675 print_taskqueue_stats_hdr(st);
3676
3677 TaskQueueStats totals;
3678 const int n = workers()->total_workers();
3679 for (int i = 0; i < n; ++i) {
3680 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3681 totals += task_queue(i)->stats;
3682 }
3683 st->print_raw("tot "); totals.print(st); st->cr();
3684
3685 DEBUG_ONLY(totals.verify());
3686 }
3687
3688 void G1CollectedHeap::reset_taskqueue_stats() {
3689 const int n = workers()->total_workers();
3690 for (int i = 0; i < n; ++i) {
3691 task_queue(i)->stats.reset();
3692 }
3693 }
3694 #endif // TASKQUEUE_STATS
3695
3696 void G1CollectedHeap::log_gc_header() {
3697 if (!G1Log::fine()) {
3698 return;
3699 }
3700
3701 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3702
3703 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3704 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3705 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3706
3707 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3708 }
3709
3710 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3711 if (!G1Log::fine()) {
3712 return;
3713 }
3714
3715 if (G1Log::finer()) {
3716 if (evacuation_failed()) {
3717 gclog_or_tty->print(" (to-space exhausted)");
3718 }
3719 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3720 g1_policy()->phase_times()->note_gc_end();
3721 g1_policy()->phase_times()->print(pause_time_sec);
3722 g1_policy()->print_detailed_heap_transition();
3723 } else {
3724 if (evacuation_failed()) {
3725 gclog_or_tty->print("--");
3726 }
3727 g1_policy()->print_heap_transition();
3728 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3729 }
3730 gclog_or_tty->flush();
3731 }
3732
3733 bool
3734 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3735 assert_at_safepoint(true /* should_be_vm_thread */);
3736 guarantee(!is_gc_active(), "collection is not reentrant");
3737
3738 if (GC_locker::check_active_before_gc()) {
3739 return false;
3740 }
3741
3742 _gc_timer_stw->register_gc_start();
3743
3744 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3745
3746 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3747 ResourceMark rm;
3748
3749 print_heap_before_gc();
3750 trace_heap_before_gc(_gc_tracer_stw);
3751
3752 verify_region_sets_optional();
3753 verify_dirty_young_regions();
3754
3755 // This call will decide whether this pause is an initial-mark
3756 // pause. If it is, during_initial_mark_pause() will return true
3757 // for the duration of this pause.
3758 g1_policy()->decide_on_conc_mark_initiation();
3759
3760 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3761 assert(!g1_policy()->during_initial_mark_pause() ||
3762 g1_policy()->gcs_are_young(), "sanity");
3763
3764 // We also do not allow mixed GCs during marking.
3765 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3766
3767 // Record whether this pause is an initial mark. When the current
3768 // thread has completed its logging output and it's safe to signal
3769 // the CM thread, the flag's value in the policy has been reset.
3770 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3771
3772 // Inner scope for scope based logging, timers, and stats collection
3773 {
3774 EvacuationInfo evacuation_info;
3775
3776 if (g1_policy()->during_initial_mark_pause()) {
3777 // We are about to start a marking cycle, so we increment the
3778 // full collection counter.
3779 increment_old_marking_cycles_started();
3780 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3781 }
3782
3783 _gc_tracer_stw->report_yc_type(yc_type());
3784
3785 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3786
3787 int active_workers = workers()->active_workers();
3788 double pause_start_sec = os::elapsedTime();
3789 g1_policy()->phase_times()->note_gc_start(active_workers);
3790 log_gc_header();
3791
3792 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3793 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3794
3795 // If the secondary_free_list is not empty, append it to the
3796 // free_list. No need to wait for the cleanup operation to finish;
3797 // the region allocation code will check the secondary_free_list
3798 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3799 // set, skip this step so that the region allocation code has to
3800 // get entries from the secondary_free_list.
3801 if (!G1StressConcRegionFreeing) {
3802 append_secondary_free_list_if_not_empty_with_lock();
3803 }
3804
3805 assert(check_young_list_well_formed(), "young list should be well formed");
3806
3807 // Don't dynamically change the number of GC threads this early. A value of
3808 // 0 is used to indicate serial work. When parallel work is done,
3809 // it will be set.
3810
3811 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3812 IsGCActiveMark x;
3813
3814 gc_prologue(false);
3815 increment_total_collections(false /* full gc */);
3816 increment_gc_time_stamp();
3817
3818 verify_before_gc();
3819
3820 check_bitmaps("GC Start");
3821
3822 COMPILER2_PRESENT(DerivedPointerTable::clear());
3823
3824 // Please see comment in g1CollectedHeap.hpp and
3825 // G1CollectedHeap::ref_processing_init() to see how
3826 // reference processing currently works in G1.
3827
3828 // Enable discovery in the STW reference processor
3829 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3830 true /*verify_no_refs*/);
3831
3832 {
3833 // We want to temporarily turn off discovery by the
3834 // CM ref processor, if necessary, and turn it back on
3835 // on again later if we do. Using a scoped
3836 // NoRefDiscovery object will do this.
3837 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3838
3839 // Forget the current alloc region (we might even choose it to be part
3840 // of the collection set!).
3841 _allocator->release_mutator_alloc_region();
3842
3843 // We should call this after we retire the mutator alloc
3844 // region(s) so that all the ALLOC / RETIRE events are generated
3845 // before the start GC event.
3846 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3847
3848 // This timing is only used by the ergonomics to handle our pause target.
3849 // It is unclear why this should not include the full pause. We will
3850 // investigate this in CR 7178365.
3851 //
3852 // Preserving the old comment here if that helps the investigation:
3853 //
3854 // The elapsed time induced by the start time below deliberately elides
3855 // the possible verification above.
3856 double sample_start_time_sec = os::elapsedTime();
3857
3858 #if YOUNG_LIST_VERBOSE
3859 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3860 _young_list->print();
3861 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3862 #endif // YOUNG_LIST_VERBOSE
3863
3864 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3865
3866 double scan_wait_start = os::elapsedTime();
3867 // We have to wait until the CM threads finish scanning the
3868 // root regions as it's the only way to ensure that all the
3869 // objects on them have been correctly scanned before we start
3870 // moving them during the GC.
3871 bool waited = _cm->root_regions()->wait_until_scan_finished();
3872 double wait_time_ms = 0.0;
3873 if (waited) {
3874 double scan_wait_end = os::elapsedTime();
3875 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3876 }
3877 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3878
3879 #if YOUNG_LIST_VERBOSE
3880 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3881 _young_list->print();
3882 #endif // YOUNG_LIST_VERBOSE
3883
3884 if (g1_policy()->during_initial_mark_pause()) {
3885 concurrent_mark()->checkpointRootsInitialPre();
3886 }
3887
3888 #if YOUNG_LIST_VERBOSE
3889 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3890 _young_list->print();
3891 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3892 #endif // YOUNG_LIST_VERBOSE
3893
3894 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3895
3896 register_humongous_regions_with_in_cset_fast_test();
3897
3898 _cm->note_start_of_gc();
3899 // We should not verify the per-thread SATB buffers given that
3900 // we have not filtered them yet (we'll do so during the
3901 // GC). We also call this after finalize_cset() to
3902 // ensure that the CSet has been finalized.
3903 _cm->verify_no_cset_oops(true /* verify_stacks */,
3904 true /* verify_enqueued_buffers */,
3905 false /* verify_thread_buffers */,
3906 true /* verify_fingers */);
3907
3908 if (_hr_printer.is_active()) {
3909 HeapRegion* hr = g1_policy()->collection_set();
3910 while (hr != NULL) {
3911 _hr_printer.cset(hr);
3912 hr = hr->next_in_collection_set();
3913 }
3914 }
3915
3916 #ifdef ASSERT
3917 VerifyCSetClosure cl;
3918 collection_set_iterate(&cl);
3919 #endif // ASSERT
3920
3921 setup_surviving_young_words();
3922
3923 // Initialize the GC alloc regions.
3924 _allocator->init_gc_alloc_regions(evacuation_info);
3925
3926 // Actually do the work...
3927 evacuate_collection_set(evacuation_info);
3928
3929 // We do this to mainly verify the per-thread SATB buffers
3930 // (which have been filtered by now) since we didn't verify
3931 // them earlier. No point in re-checking the stacks / enqueued
3932 // buffers given that the CSet has not changed since last time
3933 // we checked.
3934 _cm->verify_no_cset_oops(false /* verify_stacks */,
3935 false /* verify_enqueued_buffers */,
3936 true /* verify_thread_buffers */,
3937 true /* verify_fingers */);
3938
3939 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3940
3941 eagerly_reclaim_humongous_regions();
3942
3943 g1_policy()->clear_collection_set();
3944
3945 cleanup_surviving_young_words();
3946
3947 // Start a new incremental collection set for the next pause.
3948 g1_policy()->start_incremental_cset_building();
3949
3950 clear_cset_fast_test();
3951
3952 _young_list->reset_sampled_info();
3953
3954 // Don't check the whole heap at this point as the
3955 // GC alloc regions from this pause have been tagged
3956 // as survivors and moved on to the survivor list.
3957 // Survivor regions will fail the !is_young() check.
3958 assert(check_young_list_empty(false /* check_heap */),
3959 "young list should be empty");
3960
3961 #if YOUNG_LIST_VERBOSE
3962 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3963 _young_list->print();
3964 #endif // YOUNG_LIST_VERBOSE
3965
3966 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3967 _young_list->first_survivor_region(),
3968 _young_list->last_survivor_region());
3969
3970 _young_list->reset_auxilary_lists();
3971
3972 if (evacuation_failed()) {
3973 _allocator->set_used(recalculate_used());
3974 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3975 for (uint i = 0; i < n_queues; i++) {
3976 if (_evacuation_failed_info_array[i].has_failed()) {
3977 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3978 }
3979 }
3980 } else {
3981 // The "used" of the the collection set have already been subtracted
3982 // when they were freed. Add in the bytes evacuated.
3983 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3984 }
3985
3986 if (g1_policy()->during_initial_mark_pause()) {
3987 // We have to do this before we notify the CM threads that
3988 // they can start working to make sure that all the
3989 // appropriate initialization is done on the CM object.
3990 concurrent_mark()->checkpointRootsInitialPost();
3991 set_marking_started();
3992 // Note that we don't actually trigger the CM thread at
3993 // this point. We do that later when we're sure that
3994 // the current thread has completed its logging output.
3995 }
3996
3997 allocate_dummy_regions();
3998
3999 #if YOUNG_LIST_VERBOSE
4000 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4001 _young_list->print();
4002 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4003 #endif // YOUNG_LIST_VERBOSE
4004
4005 _allocator->init_mutator_alloc_region();
4006
4007 {
4008 size_t expand_bytes = g1_policy()->expansion_amount();
4009 if (expand_bytes > 0) {
4010 size_t bytes_before = capacity();
4011 // No need for an ergo verbose message here,
4012 // expansion_amount() does this when it returns a value > 0.
4013 if (!expand(expand_bytes)) {
4014 // We failed to expand the heap. Cannot do anything about it.
4015 }
4016 }
4017 }
4018
4019 // We redo the verification but now wrt to the new CSet which
4020 // has just got initialized after the previous CSet was freed.
4021 _cm->verify_no_cset_oops(true /* verify_stacks */,
4022 true /* verify_enqueued_buffers */,
4023 true /* verify_thread_buffers */,
4024 true /* verify_fingers */);
4025 _cm->note_end_of_gc();
4026
4027 // This timing is only used by the ergonomics to handle our pause target.
4028 // It is unclear why this should not include the full pause. We will
4029 // investigate this in CR 7178365.
4030 double sample_end_time_sec = os::elapsedTime();
4031 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4032 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4033
4034 MemoryService::track_memory_usage();
4035
4036 // In prepare_for_verify() below we'll need to scan the deferred
4037 // update buffers to bring the RSets up-to-date if
4038 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4039 // the update buffers we'll probably need to scan cards on the
4040 // regions we just allocated to (i.e., the GC alloc
4041 // regions). However, during the last GC we called
4042 // set_saved_mark() on all the GC alloc regions, so card
4043 // scanning might skip the [saved_mark_word()...top()] area of
4044 // those regions (i.e., the area we allocated objects into
4045 // during the last GC). But it shouldn't. Given that
4046 // saved_mark_word() is conditional on whether the GC time stamp
4047 // on the region is current or not, by incrementing the GC time
4048 // stamp here we invalidate all the GC time stamps on all the
4049 // regions and saved_mark_word() will simply return top() for
4050 // all the regions. This is a nicer way of ensuring this rather
4051 // than iterating over the regions and fixing them. In fact, the
4052 // GC time stamp increment here also ensures that
4053 // saved_mark_word() will return top() between pauses, i.e.,
4054 // during concurrent refinement. So we don't need the
4055 // is_gc_active() check to decided which top to use when
4056 // scanning cards (see CR 7039627).
4057 increment_gc_time_stamp();
4058
4059 verify_after_gc();
4060 check_bitmaps("GC End");
4061
4062 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4063 ref_processor_stw()->verify_no_references_recorded();
4064
4065 // CM reference discovery will be re-enabled if necessary.
4066 }
4067
4068 // We should do this after we potentially expand the heap so
4069 // that all the COMMIT events are generated before the end GC
4070 // event, and after we retire the GC alloc regions so that all
4071 // RETIRE events are generated before the end GC event.
4072 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4073
4074 #ifdef TRACESPINNING
4075 ParallelTaskTerminator::print_termination_counts();
4076 #endif
4077
4078 gc_epilogue(false);
4079 }
4080
4081 // Print the remainder of the GC log output.
4082 log_gc_footer(os::elapsedTime() - pause_start_sec);
4083
4084 // It is not yet to safe to tell the concurrent mark to
4085 // start as we have some optional output below. We don't want the
4086 // output from the concurrent mark thread interfering with this
4087 // logging output either.
4088
4089 _hrm.verify_optional();
4090 verify_region_sets_optional();
4091
4092 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4093 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4094
4095 print_heap_after_gc();
4096 trace_heap_after_gc(_gc_tracer_stw);
4097
4098 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4099 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4100 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4101 // before any GC notifications are raised.
4102 g1mm()->update_sizes();
4103
4104 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4105 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4106 _gc_timer_stw->register_gc_end();
4107 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4108 }
4109 // It should now be safe to tell the concurrent mark thread to start
4110 // without its logging output interfering with the logging output
4111 // that came from the pause.
4112
4113 if (should_start_conc_mark) {
4114 // CAUTION: after the doConcurrentMark() call below,
4115 // the concurrent marking thread(s) could be running
4116 // concurrently with us. Make sure that anything after
4117 // this point does not assume that we are the only GC thread
4118 // running. Note: of course, the actual marking work will
4119 // not start until the safepoint itself is released in
4120 // SuspendibleThreadSet::desynchronize().
4121 doConcurrentMark();
4122 }
4123
4124 return true;
4125 }
4126
4127 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4128 {
4129 size_t gclab_word_size;
4130 switch (purpose) {
4131 case GCAllocForSurvived:
4132 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4133 break;
4134 case GCAllocForTenured:
4135 gclab_word_size = _old_plab_stats.desired_plab_sz();
4136 break;
4137 default:
4138 assert(false, "unknown GCAllocPurpose");
4139 gclab_word_size = _old_plab_stats.desired_plab_sz();
4140 break;
4141 }
4142
4143 // Prevent humongous PLAB sizes for two reasons:
4144 // * PLABs are allocated using a similar paths as oops, but should
4145 // never be in a humongous region
4146 // * Allowing humongous PLABs needlessly churns the region free lists
4147 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4148 }
4149
4150 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4151 _drain_in_progress = false;
4152 set_evac_failure_closure(cl);
4153 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4154 }
4155
4156 void G1CollectedHeap::finalize_for_evac_failure() {
4157 assert(_evac_failure_scan_stack != NULL &&
4158 _evac_failure_scan_stack->length() == 0,
4159 "Postcondition");
4160 assert(!_drain_in_progress, "Postcondition");
4161 delete _evac_failure_scan_stack;
4162 _evac_failure_scan_stack = NULL;
4163 }
4164
4165 void G1CollectedHeap::remove_self_forwarding_pointers() {
4166 double remove_self_forwards_start = os::elapsedTime();
4167
4168 set_par_threads();
4169 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4170 workers()->run_task(&rsfp_task);
4171 set_par_threads(0);
4172
4173 // Now restore saved marks, if any.
4174 assert(_objs_with_preserved_marks.size() ==
4175 _preserved_marks_of_objs.size(), "Both or none.");
4176 while (!_objs_with_preserved_marks.is_empty()) {
4177 oop obj = _objs_with_preserved_marks.pop();
4178 markOop m = _preserved_marks_of_objs.pop();
4179 obj->set_mark(m);
4180 }
4181 _objs_with_preserved_marks.clear(true);
4182 _preserved_marks_of_objs.clear(true);
4183
4184 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4185 }
4186
4187 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4188 _evac_failure_scan_stack->push(obj);
4189 }
4190
4191 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4192 assert(_evac_failure_scan_stack != NULL, "precondition");
4193
4194 while (_evac_failure_scan_stack->length() > 0) {
4195 oop obj = _evac_failure_scan_stack->pop();
4196 _evac_failure_closure->set_region(heap_region_containing(obj));
4197 obj->oop_iterate_backwards(_evac_failure_closure);
4198 }
4199 }
4200
4201 oop
4202 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4203 oop old) {
4204 assert(obj_in_cs(old),
4205 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4206 (HeapWord*) old));
4207 markOop m = old->mark();
4208 oop forward_ptr = old->forward_to_atomic(old);
4209 if (forward_ptr == NULL) {
4210 // Forward-to-self succeeded.
4211 assert(_par_scan_state != NULL, "par scan state");
4212 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4213 uint queue_num = _par_scan_state->queue_num();
4214
4215 _evacuation_failed = true;
4216 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4217 if (_evac_failure_closure != cl) {
4218 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4219 assert(!_drain_in_progress,
4220 "Should only be true while someone holds the lock.");
4221 // Set the global evac-failure closure to the current thread's.
4222 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4223 set_evac_failure_closure(cl);
4224 // Now do the common part.
4225 handle_evacuation_failure_common(old, m);
4226 // Reset to NULL.
4227 set_evac_failure_closure(NULL);
4228 } else {
4229 // The lock is already held, and this is recursive.
4230 assert(_drain_in_progress, "This should only be the recursive case.");
4231 handle_evacuation_failure_common(old, m);
4232 }
4233 return old;
4234 } else {
4235 // Forward-to-self failed. Either someone else managed to allocate
4236 // space for this object (old != forward_ptr) or they beat us in
4237 // self-forwarding it (old == forward_ptr).
4238 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4239 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4240 "should not be in the CSet",
4241 (HeapWord*) old, (HeapWord*) forward_ptr));
4242 return forward_ptr;
4243 }
4244 }
4245
4246 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4247 preserve_mark_if_necessary(old, m);
4248
4249 HeapRegion* r = heap_region_containing(old);
4250 if (!r->evacuation_failed()) {
4251 r->set_evacuation_failed(true);
4252 _hr_printer.evac_failure(r);
4253 }
4254
4255 push_on_evac_failure_scan_stack(old);
4256
4257 if (!_drain_in_progress) {
4258 // prevent recursion in copy_to_survivor_space()
4259 _drain_in_progress = true;
4260 drain_evac_failure_scan_stack();
4261 _drain_in_progress = false;
4262 }
4263 }
4264
4265 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4266 assert(evacuation_failed(), "Oversaving!");
4267 // We want to call the "for_promotion_failure" version only in the
4268 // case of a promotion failure.
4269 if (m->must_be_preserved_for_promotion_failure(obj)) {
4270 _objs_with_preserved_marks.push(obj);
4271 _preserved_marks_of_objs.push(m);
4272 }
4273 }
4274
4275 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4276 size_t word_size,
4277 AllocationContext_t context) {
4278 if (purpose == GCAllocForSurvived) {
4279 HeapWord* result = survivor_attempt_allocation(word_size, context);
4280 if (result != NULL) {
4281 return result;
4282 } else {
4283 // Let's try to allocate in the old gen in case we can fit the
4284 // object there.
4285 return old_attempt_allocation(word_size, context);
4286 }
4287 } else {
4288 assert(purpose == GCAllocForTenured, "sanity");
4289 HeapWord* result = old_attempt_allocation(word_size, context);
4290 if (result != NULL) {
4291 return result;
4292 } else {
4293 // Let's try to allocate in the survivors in case we can fit the
4294 // object there.
4295 return survivor_attempt_allocation(word_size, context);
4296 }
4297 }
4298
4299 ShouldNotReachHere();
4300 // Trying to keep some compilers happy.
4301 return NULL;
4302 }
4303
4304 void G1ParCopyHelper::mark_object(oop obj) {
4305 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4306
4307 // We know that the object is not moving so it's safe to read its size.
4308 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4309 }
4310
4311 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4312 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4313 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4314 assert(from_obj != to_obj, "should not be self-forwarded");
4315
4316 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4317 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4318
4319 // The object might be in the process of being copied by another
4320 // worker so we cannot trust that its to-space image is
4321 // well-formed. So we have to read its size from its from-space
4322 // image which we know should not be changing.
4323 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4324 }
4325
4326 template <class T>
4327 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4328 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4329 _scanned_klass->record_modified_oops();
4330 }
4331 }
4332
4333 template <G1Barrier barrier, G1Mark do_mark_object>
4334 template <class T>
4335 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4336 T heap_oop = oopDesc::load_heap_oop(p);
4337
4338 if (oopDesc::is_null(heap_oop)) {
4339 return;
4340 }
4341
4342 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4343
4344 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4345
4346 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4347
4348 if (state == G1CollectedHeap::InCSet) {
4349 oop forwardee;
4350 if (obj->is_forwarded()) {
4351 forwardee = obj->forwardee();
4352 } else {
4353 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4354 }
4355 assert(forwardee != NULL, "forwardee should not be NULL");
4356 oopDesc::encode_store_heap_oop(p, forwardee);
4357 if (do_mark_object != G1MarkNone && forwardee != obj) {
4358 // If the object is self-forwarded we don't need to explicitly
4359 // mark it, the evacuation failure protocol will do so.
4360 mark_forwarded_object(obj, forwardee);
4361 }
4362
4363 if (barrier == G1BarrierKlass) {
4364 do_klass_barrier(p, forwardee);
4365 }
4366 } else {
4367 if (state == G1CollectedHeap::IsHumongous) {
4368 _g1->set_humongous_is_live(obj);
4369 }
4370 // The object is not in collection set. If we're a root scanning
4371 // closure during an initial mark pause then attempt to mark the object.
4372 if (do_mark_object == G1MarkFromRoot) {
4373 mark_object(obj);
4374 }
4375 }
4376
4377 if (barrier == G1BarrierEvac) {
4378 _par_scan_state->update_rs(_from, p, _worker_id);
4379 }
4380 }
4381
4382 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4383 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4384
4385 class G1ParEvacuateFollowersClosure : public VoidClosure {
4386 protected:
4387 G1CollectedHeap* _g1h;
4388 G1ParScanThreadState* _par_scan_state;
4389 RefToScanQueueSet* _queues;
4390 ParallelTaskTerminator* _terminator;
4391
4392 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4393 RefToScanQueueSet* queues() { return _queues; }
4394 ParallelTaskTerminator* terminator() { return _terminator; }
4395
4396 public:
4397 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4398 G1ParScanThreadState* par_scan_state,
4399 RefToScanQueueSet* queues,
4400 ParallelTaskTerminator* terminator)
4401 : _g1h(g1h), _par_scan_state(par_scan_state),
4402 _queues(queues), _terminator(terminator) {}
4403
4404 void do_void();
4405
4406 private:
4407 inline bool offer_termination();
4408 };
4409
4410 bool G1ParEvacuateFollowersClosure::offer_termination() {
4411 G1ParScanThreadState* const pss = par_scan_state();
4412 pss->start_term_time();
4413 const bool res = terminator()->offer_termination();
4414 pss->end_term_time();
4415 return res;
4416 }
4417
4418 void G1ParEvacuateFollowersClosure::do_void() {
4419 G1ParScanThreadState* const pss = par_scan_state();
4420 pss->trim_queue();
4421 do {
4422 pss->steal_and_trim_queue(queues());
4423 } while (!offer_termination());
4424 }
4425
4426 class G1KlassScanClosure : public KlassClosure {
4427 G1ParCopyHelper* _closure;
4428 bool _process_only_dirty;
4429 int _count;
4430 public:
4431 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4432 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4433 void do_klass(Klass* klass) {
4434 // If the klass has not been dirtied we know that there's
4435 // no references into the young gen and we can skip it.
4436 if (!_process_only_dirty || klass->has_modified_oops()) {
4437 // Clean the klass since we're going to scavenge all the metadata.
4438 klass->clear_modified_oops();
4439
4440 // Tell the closure that this klass is the Klass to scavenge
4441 // and is the one to dirty if oops are left pointing into the young gen.
4442 _closure->set_scanned_klass(klass);
4443
4444 klass->oops_do(_closure);
4445
4446 _closure->set_scanned_klass(NULL);
4447 }
4448 _count++;
4449 }
4450 };
4451
4452 class G1CodeBlobClosure : public CodeBlobClosure {
4453 class HeapRegionGatheringOopClosure : public OopClosure {
4454 G1CollectedHeap* _g1h;
4455 OopClosure* _work;
4456 nmethod* _nm;
4457
4458 template <typename T>
4459 void do_oop_work(T* p) {
4460 _work->do_oop(p);
4461 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4462 if (!oopDesc::is_null(oop_or_narrowoop)) {
4463 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4464 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4465 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");
4466 hr->add_strong_code_root(_nm);
4467 }
4468 }
4469
4470 public:
4471 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4472
4473 void do_oop(oop* o) {
4474 do_oop_work(o);
4475 }
4476
4477 void do_oop(narrowOop* o) {
4478 do_oop_work(o);
4479 }
4480
4481 void set_nm(nmethod* nm) {
4482 _nm = nm;
4483 }
4484 };
4485
4486 HeapRegionGatheringOopClosure _oc;
4487 public:
4488 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4489
4490 void do_code_blob(CodeBlob* cb) {
4491 nmethod* nm = cb->as_nmethod_or_null();
4492 if (nm != NULL) {
4493 if (!nm->test_set_oops_do_mark()) {
4494 _oc.set_nm(nm);
4495 nm->oops_do(&_oc);
4496 nm->fix_oop_relocations();
4497 }
4498 }
4499 }
4500 };
4501
4502 class G1ParTask : public AbstractGangTask {
4503 protected:
4504 G1CollectedHeap* _g1h;
4505 RefToScanQueueSet *_queues;
4506 ParallelTaskTerminator _terminator;
4507 uint _n_workers;
4508
4509 Mutex _stats_lock;
4510 Mutex* stats_lock() { return &_stats_lock; }
4511
4512 public:
4513 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4514 : AbstractGangTask("G1 collection"),
4515 _g1h(g1h),
4516 _queues(task_queues),
4517 _terminator(0, _queues),
4518 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4519 {}
4520
4521 RefToScanQueueSet* queues() { return _queues; }
4522
4523 RefToScanQueue *work_queue(int i) {
4524 return queues()->queue(i);
4525 }
4526
4527 ParallelTaskTerminator* terminator() { return &_terminator; }
4528
4529 virtual void set_for_termination(int active_workers) {
4530 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4531 // in the young space (_par_seq_tasks) in the G1 heap
4532 // for SequentialSubTasksDone.
4533 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4534 // both of which need setting by set_n_termination().
4535 _g1h->SharedHeap::set_n_termination(active_workers);
4536 _g1h->set_n_termination(active_workers);
4537 terminator()->reset_for_reuse(active_workers);
4538 _n_workers = active_workers;
4539 }
4540
4541 // Helps out with CLD processing.
4542 //
4543 // During InitialMark we need to:
4544 // 1) Scavenge all CLDs for the young GC.
4545 // 2) Mark all objects directly reachable from strong CLDs.
4546 template <G1Mark do_mark_object>
4547 class G1CLDClosure : public CLDClosure {
4548 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4549 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4550 G1KlassScanClosure _klass_in_cld_closure;
4551 bool _claim;
4552
4553 public:
4554 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4555 bool only_young, bool claim)
4556 : _oop_closure(oop_closure),
4557 _oop_in_klass_closure(oop_closure->g1(),
4558 oop_closure->pss(),
4559 oop_closure->rp()),
4560 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4561 _claim(claim) {
4562
4563 }
4564
4565 void do_cld(ClassLoaderData* cld) {
4566 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4567 }
4568 };
4569
4570 void work(uint worker_id) {
4571 if (worker_id >= _n_workers) return; // no work needed this round
4572
4573 double start_time_ms = os::elapsedTime() * 1000.0;
4574 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4575
4576 {
4577 ResourceMark rm;
4578 HandleMark hm;
4579
4580 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4581
4582 G1ParScanThreadState pss(_g1h, worker_id, rp);
4583 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4584
4585 pss.set_evac_failure_closure(&evac_failure_cl);
4586
4587 bool only_young = _g1h->g1_policy()->gcs_are_young();
4588
4589 // Non-IM young GC.
4590 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4591 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4592 only_young, // Only process dirty klasses.
4593 false); // No need to claim CLDs.
4594 // IM young GC.
4595 // Strong roots closures.
4596 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4597 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4598 false, // Process all klasses.
4599 true); // Need to claim CLDs.
4600 // Weak roots closures.
4601 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4602 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4603 false, // Process all klasses.
4604 true); // Need to claim CLDs.
4605
4606 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4607 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4608 // IM Weak code roots are handled later.
4609
4610 OopClosure* strong_root_cl;
4611 OopClosure* weak_root_cl;
4612 CLDClosure* strong_cld_cl;
4613 CLDClosure* weak_cld_cl;
4614 CodeBlobClosure* strong_code_cl;
4615
4616 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4617 // We also need to mark copied objects.
4618 strong_root_cl = &scan_mark_root_cl;
4619 strong_cld_cl = &scan_mark_cld_cl;
4620 strong_code_cl = &scan_mark_code_cl;
4621 if (ClassUnloadingWithConcurrentMark) {
4622 weak_root_cl = &scan_mark_weak_root_cl;
4623 weak_cld_cl = &scan_mark_weak_cld_cl;
4624 } else {
4625 weak_root_cl = &scan_mark_root_cl;
4626 weak_cld_cl = &scan_mark_cld_cl;
4627 }
4628 } else {
4629 strong_root_cl = &scan_only_root_cl;
4630 weak_root_cl = &scan_only_root_cl;
4631 strong_cld_cl = &scan_only_cld_cl;
4632 weak_cld_cl = &scan_only_cld_cl;
4633 strong_code_cl = &scan_only_code_cl;
4634 }
4635
4636
4637 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4638
4639 pss.start_strong_roots();
4640 _g1h->g1_process_roots(strong_root_cl,
4641 weak_root_cl,
4642 &push_heap_rs_cl,
4643 strong_cld_cl,
4644 weak_cld_cl,
4645 strong_code_cl,
4646 worker_id);
4647
4648 pss.end_strong_roots();
4649
4650 {
4651 double start = os::elapsedTime();
4652 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4653 evac.do_void();
4654 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4655 double term_ms = pss.term_time()*1000.0;
4656 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4657 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4658 }
4659 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4660 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4661
4662 if (PrintTerminationStats) {
4663 MutexLocker x(stats_lock());
4664 pss.print_termination_stats(worker_id);
4665 }
4666
4667 assert(pss.queue_is_empty(), "should be empty");
4668
4669 // Close the inner scope so that the ResourceMark and HandleMark
4670 // destructors are executed here and are included as part of the
4671 // "GC Worker Time".
4672 }
4673
4674 double end_time_ms = os::elapsedTime() * 1000.0;
4675 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4676 }
4677 };
4678
4679 // *** Common G1 Evacuation Stuff
4680
4681 // This method is run in a GC worker.
4682
4683 void
4684 G1CollectedHeap::
4685 g1_process_roots(OopClosure* scan_non_heap_roots,
4686 OopClosure* scan_non_heap_weak_roots,
4687 OopsInHeapRegionClosure* scan_rs,
4688 CLDClosure* scan_strong_clds,
4689 CLDClosure* scan_weak_clds,
4690 CodeBlobClosure* scan_strong_code,
4691 uint worker_i) {
4692
4693 // First scan the shared roots.
4694 double ext_roots_start = os::elapsedTime();
4695 double closure_app_time_sec = 0.0;
4696
4697 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4698 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4699
4700 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4701 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4702
4703 process_roots(false, // no scoping; this is parallel code
4704 SharedHeap::SO_None,
4705 &buf_scan_non_heap_roots,
4706 &buf_scan_non_heap_weak_roots,
4707 scan_strong_clds,
4708 // Unloading Initial Marks handle the weak CLDs separately.
4709 (trace_metadata ? NULL : scan_weak_clds),
4710 scan_strong_code);
4711
4712 // Now the CM ref_processor roots.
4713 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4714 // We need to treat the discovered reference lists of the
4715 // concurrent mark ref processor as roots and keep entries
4716 // (which are added by the marking threads) on them live
4717 // until they can be processed at the end of marking.
4718 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4719 }
4720
4721 if (trace_metadata) {
4722 // Barrier to make sure all workers passed
4723 // the strong CLD and strong nmethods phases.
4724 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4725
4726 // Now take the complement of the strong CLDs.
4727 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4728 }
4729
4730 // Finish up any enqueued closure apps (attributed as object copy time).
4731 buf_scan_non_heap_roots.done();
4732 buf_scan_non_heap_weak_roots.done();
4733
4734 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4735 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4736
4737 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4738
4739 double ext_root_time_ms =
4740 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4741
4742 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4743
4744 // During conc marking we have to filter the per-thread SATB buffers
4745 // to make sure we remove any oops into the CSet (which will show up
4746 // as implicitly live).
4747 double satb_filtering_ms = 0.0;
4748 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4749 if (mark_in_progress()) {
4750 double satb_filter_start = os::elapsedTime();
4751
4752 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4753
4754 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4755 }
4756 }
4757 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4758
4759 // Now scan the complement of the collection set.
4760 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4761
4762 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4763
4764 _process_strong_tasks->all_tasks_completed();
4765 }
4766
4767 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4768 private:
4769 BoolObjectClosure* _is_alive;
4770 int _initial_string_table_size;
4771 int _initial_symbol_table_size;
4772
4773 bool _process_strings;
4774 int _strings_processed;
4775 int _strings_removed;
4776
4777 bool _process_symbols;
4778 int _symbols_processed;
4779 int _symbols_removed;
4780
4781 public:
4782 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4783 AbstractGangTask("String/Symbol Unlinking"),
4784 _is_alive(is_alive),
4785 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4786 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4787
4788 _initial_string_table_size = StringTable::the_table()->table_size();
4789 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4790 if (process_strings) {
4791 StringTable::clear_parallel_claimed_index();
4792 }
4793 if (process_symbols) {
4794 SymbolTable::clear_parallel_claimed_index();
4795 }
4796 }
4797
4798 ~G1StringSymbolTableUnlinkTask() {
4799 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4800 err_msg("claim value %d after unlink less than initial string table size %d",
4801 StringTable::parallel_claimed_index(), _initial_string_table_size));
4802 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4803 err_msg("claim value %d after unlink less than initial symbol table size %d",
4804 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4805
4806 if (G1TraceStringSymbolTableScrubbing) {
4807 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4808 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4809 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4810 strings_processed(), strings_removed(),
4811 symbols_processed(), symbols_removed());
4812 }
4813 }
4814
4815 void work(uint worker_id) {
4816 int strings_processed = 0;
4817 int strings_removed = 0;
4818 int symbols_processed = 0;
4819 int symbols_removed = 0;
4820 if (_process_strings) {
4821 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4822 Atomic::add(strings_processed, &_strings_processed);
4823 Atomic::add(strings_removed, &_strings_removed);
4824 }
4825 if (_process_symbols) {
4826 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4827 Atomic::add(symbols_processed, &_symbols_processed);
4828 Atomic::add(symbols_removed, &_symbols_removed);
4829 }
4830 }
4831
4832 size_t strings_processed() const { return (size_t)_strings_processed; }
4833 size_t strings_removed() const { return (size_t)_strings_removed; }
4834
4835 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4836 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4837 };
4838
4839 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4840 private:
4841 static Monitor* _lock;
4842
4843 BoolObjectClosure* const _is_alive;
4844 const bool _unloading_occurred;
4845 const uint _num_workers;
4846
4847 // Variables used to claim nmethods.
4848 nmethod* _first_nmethod;
4849 volatile nmethod* _claimed_nmethod;
4850
4851 // The list of nmethods that need to be processed by the second pass.
4852 volatile nmethod* _postponed_list;
4853 volatile uint _num_entered_barrier;
4854
4855 public:
4856 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4857 _is_alive(is_alive),
4858 _unloading_occurred(unloading_occurred),
4859 _num_workers(num_workers),
4860 _first_nmethod(NULL),
4861 _claimed_nmethod(NULL),
4862 _postponed_list(NULL),
4863 _num_entered_barrier(0)
4864 {
4865 nmethod::increase_unloading_clock();
4866 // Get first alive nmethod
4867 NMethodIterator iter = NMethodIterator();
4868 if(iter.next_alive()) {
4869 _first_nmethod = iter.method();
4870 }
4871 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4872 }
4873
4874 ~G1CodeCacheUnloadingTask() {
4875 CodeCache::verify_clean_inline_caches();
4876
4877 CodeCache::set_needs_cache_clean(false);
4878 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4879
4880 CodeCache::verify_icholder_relocations();
4881 }
4882
4883 private:
4884 void add_to_postponed_list(nmethod* nm) {
4885 nmethod* old;
4886 do {
4887 old = (nmethod*)_postponed_list;
4888 nm->set_unloading_next(old);
4889 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4890 }
4891
4892 void clean_nmethod(nmethod* nm) {
4893 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4894
4895 if (postponed) {
4896 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4897 add_to_postponed_list(nm);
4898 }
4899
4900 // Mark that this thread has been cleaned/unloaded.
4901 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4902 nm->set_unloading_clock(nmethod::global_unloading_clock());
4903 }
4904
4905 void clean_nmethod_postponed(nmethod* nm) {
4906 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4907 }
4908
4909 static const int MaxClaimNmethods = 16;
4910
4911 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4912 nmethod* first;
4913 NMethodIterator last;
4914
4915 do {
4916 *num_claimed_nmethods = 0;
4917
4918 first = (nmethod*)_claimed_nmethod;
4919 last = NMethodIterator(first);
4920
4921 if (first != NULL) {
4922
4923 for (int i = 0; i < MaxClaimNmethods; i++) {
4924 if (!last.next_alive()) {
4925 break;
4926 }
4927 claimed_nmethods[i] = last.method();
4928 (*num_claimed_nmethods)++;
4929 }
4930 }
4931
4932 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4933 }
4934
4935 nmethod* claim_postponed_nmethod() {
4936 nmethod* claim;
4937 nmethod* next;
4938
4939 do {
4940 claim = (nmethod*)_postponed_list;
4941 if (claim == NULL) {
4942 return NULL;
4943 }
4944
4945 next = claim->unloading_next();
4946
4947 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4948
4949 return claim;
4950 }
4951
4952 public:
4953 // Mark that we're done with the first pass of nmethod cleaning.
4954 void barrier_mark(uint worker_id) {
4955 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4956 _num_entered_barrier++;
4957 if (_num_entered_barrier == _num_workers) {
4958 ml.notify_all();
4959 }
4960 }
4961
4962 // See if we have to wait for the other workers to
4963 // finish their first-pass nmethod cleaning work.
4964 void barrier_wait(uint worker_id) {
4965 if (_num_entered_barrier < _num_workers) {
4966 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4967 while (_num_entered_barrier < _num_workers) {
4968 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4969 }
4970 }
4971 }
4972
4973 // Cleaning and unloading of nmethods. Some work has to be postponed
4974 // to the second pass, when we know which nmethods survive.
4975 void work_first_pass(uint worker_id) {
4976 // The first nmethods is claimed by the first worker.
4977 if (worker_id == 0 && _first_nmethod != NULL) {
4978 clean_nmethod(_first_nmethod);
4979 _first_nmethod = NULL;
4980 }
4981
4982 int num_claimed_nmethods;
4983 nmethod* claimed_nmethods[MaxClaimNmethods];
4984
4985 while (true) {
4986 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4987
4988 if (num_claimed_nmethods == 0) {
4989 break;
4990 }
4991
4992 for (int i = 0; i < num_claimed_nmethods; i++) {
4993 clean_nmethod(claimed_nmethods[i]);
4994 }
4995 }
4996
4997 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4998 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4999 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
5000 }
5001
5002 void work_second_pass(uint worker_id) {
5003 nmethod* nm;
5004 // Take care of postponed nmethods.
5005 while ((nm = claim_postponed_nmethod()) != NULL) {
5006 clean_nmethod_postponed(nm);
5007 }
5008 }
5009 };
5010
5011 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5012
5013 class G1KlassCleaningTask : public StackObj {
5014 BoolObjectClosure* _is_alive;
5015 volatile jint _clean_klass_tree_claimed;
5016 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5017
5018 public:
5019 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5020 _is_alive(is_alive),
5021 _clean_klass_tree_claimed(0),
5022 _klass_iterator() {
5023 }
5024
5025 private:
5026 bool claim_clean_klass_tree_task() {
5027 if (_clean_klass_tree_claimed) {
5028 return false;
5029 }
5030
5031 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5032 }
5033
5034 InstanceKlass* claim_next_klass() {
5035 Klass* klass;
5036 do {
5037 klass =_klass_iterator.next_klass();
5038 } while (klass != NULL && !klass->oop_is_instance());
5039
5040 return (InstanceKlass*)klass;
5041 }
5042
5043 public:
5044
5045 void clean_klass(InstanceKlass* ik) {
5046 ik->clean_implementors_list(_is_alive);
5047 ik->clean_method_data(_is_alive);
5048
5049 // G1 specific cleanup work that has
5050 // been moved here to be done in parallel.
5051 ik->clean_dependent_nmethods();
5052 if (JvmtiExport::has_redefined_a_class()) {
5053 InstanceKlass::purge_previous_versions(ik);
5054 }
5055 }
5056
5057 void work() {
5058 ResourceMark rm;
5059
5060 // One worker will clean the subklass/sibling klass tree.
5061 if (claim_clean_klass_tree_task()) {
5062 Klass::clean_subklass_tree(_is_alive);
5063 }
5064
5065 // All workers will help cleaning the classes,
5066 InstanceKlass* klass;
5067 while ((klass = claim_next_klass()) != NULL) {
5068 clean_klass(klass);
5069 }
5070 }
5071 };
5072
5073 // To minimize the remark pause times, the tasks below are done in parallel.
5074 class G1ParallelCleaningTask : public AbstractGangTask {
5075 private:
5076 G1StringSymbolTableUnlinkTask _string_symbol_task;
5077 G1CodeCacheUnloadingTask _code_cache_task;
5078 G1KlassCleaningTask _klass_cleaning_task;
5079
5080 public:
5081 // The constructor is run in the VMThread.
5082 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5083 AbstractGangTask("Parallel Cleaning"),
5084 _string_symbol_task(is_alive, process_strings, process_symbols),
5085 _code_cache_task(num_workers, is_alive, unloading_occurred),
5086 _klass_cleaning_task(is_alive) {
5087 }
5088
5089 void pre_work_verification() {
5090 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5091 }
5092
5093 void post_work_verification() {
5094 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5095 }
5096
5097 // The parallel work done by all worker threads.
5098 void work(uint worker_id) {
5099 pre_work_verification();
5100
5101 // Do first pass of code cache cleaning.
5102 _code_cache_task.work_first_pass(worker_id);
5103
5104 // Let the threads mark that the first pass is done.
5105 _code_cache_task.barrier_mark(worker_id);
5106
5107 // Clean the Strings and Symbols.
5108 _string_symbol_task.work(worker_id);
5109
5110 // Wait for all workers to finish the first code cache cleaning pass.
5111 _code_cache_task.barrier_wait(worker_id);
5112
5113 // Do the second code cache cleaning work, which realize on
5114 // the liveness information gathered during the first pass.
5115 _code_cache_task.work_second_pass(worker_id);
5116
5117 // Clean all klasses that were not unloaded.
5118 _klass_cleaning_task.work();
5119
5120 post_work_verification();
5121 }
5122 };
5123
5124
5125 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5126 bool process_strings,
5127 bool process_symbols,
5128 bool class_unloading_occurred) {
5129 uint n_workers = workers()->active_workers();
5130
5131 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5132 n_workers, class_unloading_occurred);
5133 set_par_threads(n_workers);
5134 workers()->run_task(&g1_unlink_task);
5135 set_par_threads(0);
5136 }
5137
5138 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5139 bool process_strings, bool process_symbols) {
5140 {
5141 uint n_workers = _g1h->workers()->active_workers();
5142 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5143 set_par_threads(n_workers);
5144 workers()->run_task(&g1_unlink_task);
5145 set_par_threads(0);
5146 }
5147
5148 if (G1StringDedup::is_enabled()) {
5149 G1StringDedup::unlink(is_alive);
5150 }
5151 }
5152
5153 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5154 private:
5155 DirtyCardQueueSet* _queue;
5156 public:
5157 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5158
5159 virtual void work(uint worker_id) {
5160 double start_time = os::elapsedTime();
5161
5162 RedirtyLoggedCardTableEntryClosure cl;
5163 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5164
5165 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5166 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5167 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5168 }
5169 };
5170
5171 void G1CollectedHeap::redirty_logged_cards() {
5172 double redirty_logged_cards_start = os::elapsedTime();
5173
5174 uint n_workers = _g1h->workers()->active_workers();
5175
5176 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5177 dirty_card_queue_set().reset_for_par_iteration();
5178 set_par_threads(n_workers);
5179 workers()->run_task(&redirty_task);
5180 set_par_threads(0);
5181
5182 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5183 dcq.merge_bufferlists(&dirty_card_queue_set());
5184 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5185
5186 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5187 }
5188
5189 // Weak Reference Processing support
5190
5191 // An always "is_alive" closure that is used to preserve referents.
5192 // If the object is non-null then it's alive. Used in the preservation
5193 // of referent objects that are pointed to by reference objects
5194 // discovered by the CM ref processor.
5195 class G1AlwaysAliveClosure: public BoolObjectClosure {
5196 G1CollectedHeap* _g1;
5197 public:
5198 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5199 bool do_object_b(oop p) {
5200 if (p != NULL) {
5201 return true;
5202 }
5203 return false;
5204 }
5205 };
5206
5207 bool G1STWIsAliveClosure::do_object_b(oop p) {
5208 // An object is reachable if it is outside the collection set,
5209 // or is inside and copied.
5210 return !_g1->obj_in_cs(p) || p->is_forwarded();
5211 }
5212
5213 // Non Copying Keep Alive closure
5214 class G1KeepAliveClosure: public OopClosure {
5215 G1CollectedHeap* _g1;
5216 public:
5217 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5218 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5219 void do_oop(oop* p) {
5220 oop obj = *p;
5221 assert(obj != NULL, "the caller should have filtered out NULL values");
5222
5223 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5224 if (cset_state == G1CollectedHeap::InNeither) {
5225 return;
5226 }
5227 if (cset_state == G1CollectedHeap::InCSet) {
5228 assert( obj->is_forwarded(), "invariant" );
5229 *p = obj->forwardee();
5230 } else {
5231 assert(!obj->is_forwarded(), "invariant" );
5232 assert(cset_state == G1CollectedHeap::IsHumongous,
5233 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5234 _g1->set_humongous_is_live(obj);
5235 }
5236 }
5237 };
5238
5239 // Copying Keep Alive closure - can be called from both
5240 // serial and parallel code as long as different worker
5241 // threads utilize different G1ParScanThreadState instances
5242 // and different queues.
5243
5244 class G1CopyingKeepAliveClosure: public OopClosure {
5245 G1CollectedHeap* _g1h;
5246 OopClosure* _copy_non_heap_obj_cl;
5247 G1ParScanThreadState* _par_scan_state;
5248
5249 public:
5250 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5251 OopClosure* non_heap_obj_cl,
5252 G1ParScanThreadState* pss):
5253 _g1h(g1h),
5254 _copy_non_heap_obj_cl(non_heap_obj_cl),
5255 _par_scan_state(pss)
5256 {}
5257
5258 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5259 virtual void do_oop( oop* p) { do_oop_work(p); }
5260
5261 template <class T> void do_oop_work(T* p) {
5262 oop obj = oopDesc::load_decode_heap_oop(p);
5263
5264 if (_g1h->is_in_cset_or_humongous(obj)) {
5265 // If the referent object has been forwarded (either copied
5266 // to a new location or to itself in the event of an
5267 // evacuation failure) then we need to update the reference
5268 // field and, if both reference and referent are in the G1
5269 // heap, update the RSet for the referent.
5270 //
5271 // If the referent has not been forwarded then we have to keep
5272 // it alive by policy. Therefore we have copy the referent.
5273 //
5274 // If the reference field is in the G1 heap then we can push
5275 // on the PSS queue. When the queue is drained (after each
5276 // phase of reference processing) the object and it's followers
5277 // will be copied, the reference field set to point to the
5278 // new location, and the RSet updated. Otherwise we need to
5279 // use the the non-heap or metadata closures directly to copy
5280 // the referent object and update the pointer, while avoiding
5281 // updating the RSet.
5282
5283 if (_g1h->is_in_g1_reserved(p)) {
5284 _par_scan_state->push_on_queue(p);
5285 } else {
5286 assert(!Metaspace::contains((const void*)p),
5287 err_msg("Unexpectedly found a pointer from metadata: "
5288 PTR_FORMAT, p));
5289 _copy_non_heap_obj_cl->do_oop(p);
5290 }
5291 }
5292 }
5293 };
5294
5295 // Serial drain queue closure. Called as the 'complete_gc'
5296 // closure for each discovered list in some of the
5297 // reference processing phases.
5298
5299 class G1STWDrainQueueClosure: public VoidClosure {
5300 protected:
5301 G1CollectedHeap* _g1h;
5302 G1ParScanThreadState* _par_scan_state;
5303
5304 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5305
5306 public:
5307 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5308 _g1h(g1h),
5309 _par_scan_state(pss)
5310 { }
5311
5312 void do_void() {
5313 G1ParScanThreadState* const pss = par_scan_state();
5314 pss->trim_queue();
5315 }
5316 };
5317
5318 // Parallel Reference Processing closures
5319
5320 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5321 // processing during G1 evacuation pauses.
5322
5323 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5324 private:
5325 G1CollectedHeap* _g1h;
5326 RefToScanQueueSet* _queues;
5327 FlexibleWorkGang* _workers;
5328 int _active_workers;
5329
5330 public:
5331 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5332 FlexibleWorkGang* workers,
5333 RefToScanQueueSet *task_queues,
5334 int n_workers) :
5335 _g1h(g1h),
5336 _queues(task_queues),
5337 _workers(workers),
5338 _active_workers(n_workers)
5339 {
5340 assert(n_workers > 0, "shouldn't call this otherwise");
5341 }
5342
5343 // Executes the given task using concurrent marking worker threads.
5344 virtual void execute(ProcessTask& task);
5345 virtual void execute(EnqueueTask& task);
5346 };
5347
5348 // Gang task for possibly parallel reference processing
5349
5350 class G1STWRefProcTaskProxy: public AbstractGangTask {
5351 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5352 ProcessTask& _proc_task;
5353 G1CollectedHeap* _g1h;
5354 RefToScanQueueSet *_task_queues;
5355 ParallelTaskTerminator* _terminator;
5356
5357 public:
5358 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5359 G1CollectedHeap* g1h,
5360 RefToScanQueueSet *task_queues,
5361 ParallelTaskTerminator* terminator) :
5362 AbstractGangTask("Process reference objects in parallel"),
5363 _proc_task(proc_task),
5364 _g1h(g1h),
5365 _task_queues(task_queues),
5366 _terminator(terminator)
5367 {}
5368
5369 virtual void work(uint worker_id) {
5370 // The reference processing task executed by a single worker.
5371 ResourceMark rm;
5372 HandleMark hm;
5373
5374 G1STWIsAliveClosure is_alive(_g1h);
5375
5376 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5377 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5378
5379 pss.set_evac_failure_closure(&evac_failure_cl);
5380
5381 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5382
5383 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5384
5385 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5386
5387 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5388 // We also need to mark copied objects.
5389 copy_non_heap_cl = ©_mark_non_heap_cl;
5390 }
5391
5392 // Keep alive closure.
5393 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5394
5395 // Complete GC closure
5396 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5397
5398 // Call the reference processing task's work routine.
5399 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5400
5401 // Note we cannot assert that the refs array is empty here as not all
5402 // of the processing tasks (specifically phase2 - pp2_work) execute
5403 // the complete_gc closure (which ordinarily would drain the queue) so
5404 // the queue may not be empty.
5405 }
5406 };
5407
5408 // Driver routine for parallel reference processing.
5409 // Creates an instance of the ref processing gang
5410 // task and has the worker threads execute it.
5411 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5412 assert(_workers != NULL, "Need parallel worker threads.");
5413
5414 ParallelTaskTerminator terminator(_active_workers, _queues);
5415 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5416
5417 _g1h->set_par_threads(_active_workers);
5418 _workers->run_task(&proc_task_proxy);
5419 _g1h->set_par_threads(0);
5420 }
5421
5422 // Gang task for parallel reference enqueueing.
5423
5424 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5425 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5426 EnqueueTask& _enq_task;
5427
5428 public:
5429 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5430 AbstractGangTask("Enqueue reference objects in parallel"),
5431 _enq_task(enq_task)
5432 { }
5433
5434 virtual void work(uint worker_id) {
5435 _enq_task.work(worker_id);
5436 }
5437 };
5438
5439 // Driver routine for parallel reference enqueueing.
5440 // Creates an instance of the ref enqueueing gang
5441 // task and has the worker threads execute it.
5442
5443 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5444 assert(_workers != NULL, "Need parallel worker threads.");
5445
5446 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5447
5448 _g1h->set_par_threads(_active_workers);
5449 _workers->run_task(&enq_task_proxy);
5450 _g1h->set_par_threads(0);
5451 }
5452
5453 // End of weak reference support closures
5454
5455 // Abstract task used to preserve (i.e. copy) any referent objects
5456 // that are in the collection set and are pointed to by reference
5457 // objects discovered by the CM ref processor.
5458
5459 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5460 protected:
5461 G1CollectedHeap* _g1h;
5462 RefToScanQueueSet *_queues;
5463 ParallelTaskTerminator _terminator;
5464 uint _n_workers;
5465
5466 public:
5467 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5468 AbstractGangTask("ParPreserveCMReferents"),
5469 _g1h(g1h),
5470 _queues(task_queues),
5471 _terminator(workers, _queues),
5472 _n_workers(workers)
5473 { }
5474
5475 void work(uint worker_id) {
5476 ResourceMark rm;
5477 HandleMark hm;
5478
5479 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5480 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5481
5482 pss.set_evac_failure_closure(&evac_failure_cl);
5483
5484 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5485
5486 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5487
5488 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5489
5490 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5491
5492 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5493 // We also need to mark copied objects.
5494 copy_non_heap_cl = ©_mark_non_heap_cl;
5495 }
5496
5497 // Is alive closure
5498 G1AlwaysAliveClosure always_alive(_g1h);
5499
5500 // Copying keep alive closure. Applied to referent objects that need
5501 // to be copied.
5502 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5503
5504 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5505
5506 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5507 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5508
5509 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5510 // So this must be true - but assert just in case someone decides to
5511 // change the worker ids.
5512 assert(0 <= worker_id && worker_id < limit, "sanity");
5513 assert(!rp->discovery_is_atomic(), "check this code");
5514
5515 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5516 for (uint idx = worker_id; idx < limit; idx += stride) {
5517 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5518
5519 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5520 while (iter.has_next()) {
5521 // Since discovery is not atomic for the CM ref processor, we
5522 // can see some null referent objects.
5523 iter.load_ptrs(DEBUG_ONLY(true));
5524 oop ref = iter.obj();
5525
5526 // This will filter nulls.
5527 if (iter.is_referent_alive()) {
5528 iter.make_referent_alive();
5529 }
5530 iter.move_to_next();
5531 }
5532 }
5533
5534 // Drain the queue - which may cause stealing
5535 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5536 drain_queue.do_void();
5537 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5538 assert(pss.queue_is_empty(), "should be");
5539 }
5540 };
5541
5542 // Weak Reference processing during an evacuation pause (part 1).
5543 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5544 double ref_proc_start = os::elapsedTime();
5545
5546 ReferenceProcessor* rp = _ref_processor_stw;
5547 assert(rp->discovery_enabled(), "should have been enabled");
5548
5549 // Any reference objects, in the collection set, that were 'discovered'
5550 // by the CM ref processor should have already been copied (either by
5551 // applying the external root copy closure to the discovered lists, or
5552 // by following an RSet entry).
5553 //
5554 // But some of the referents, that are in the collection set, that these
5555 // reference objects point to may not have been copied: the STW ref
5556 // processor would have seen that the reference object had already
5557 // been 'discovered' and would have skipped discovering the reference,
5558 // but would not have treated the reference object as a regular oop.
5559 // As a result the copy closure would not have been applied to the
5560 // referent object.
5561 //
5562 // We need to explicitly copy these referent objects - the references
5563 // will be processed at the end of remarking.
5564 //
5565 // We also need to do this copying before we process the reference
5566 // objects discovered by the STW ref processor in case one of these
5567 // referents points to another object which is also referenced by an
5568 // object discovered by the STW ref processor.
5569
5570 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5571
5572 set_par_threads(no_of_gc_workers);
5573 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5574 no_of_gc_workers,
5575 _task_queues);
5576
5577 workers()->run_task(&keep_cm_referents);
5578
5579 set_par_threads(0);
5580
5581 // Closure to test whether a referent is alive.
5582 G1STWIsAliveClosure is_alive(this);
5583
5584 // Even when parallel reference processing is enabled, the processing
5585 // of JNI refs is serial and performed serially by the current thread
5586 // rather than by a worker. The following PSS will be used for processing
5587 // JNI refs.
5588
5589 // Use only a single queue for this PSS.
5590 G1ParScanThreadState pss(this, 0, NULL);
5591
5592 // We do not embed a reference processor in the copying/scanning
5593 // closures while we're actually processing the discovered
5594 // reference objects.
5595 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5596
5597 pss.set_evac_failure_closure(&evac_failure_cl);
5598
5599 assert(pss.queue_is_empty(), "pre-condition");
5600
5601 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5602
5603 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5604
5605 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5606
5607 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5608 // We also need to mark copied objects.
5609 copy_non_heap_cl = ©_mark_non_heap_cl;
5610 }
5611
5612 // Keep alive closure.
5613 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5614
5615 // Serial Complete GC closure
5616 G1STWDrainQueueClosure drain_queue(this, &pss);
5617
5618 // Setup the soft refs policy...
5619 rp->setup_policy(false);
5620
5621 ReferenceProcessorStats stats;
5622 if (!rp->processing_is_mt()) {
5623 // Serial reference processing...
5624 stats = rp->process_discovered_references(&is_alive,
5625 &keep_alive,
5626 &drain_queue,
5627 NULL,
5628 _gc_timer_stw,
5629 _gc_tracer_stw->gc_id());
5630 } else {
5631 // Parallel reference processing
5632 assert(rp->num_q() == no_of_gc_workers, "sanity");
5633 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5634
5635 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5636 stats = rp->process_discovered_references(&is_alive,
5637 &keep_alive,
5638 &drain_queue,
5639 &par_task_executor,
5640 _gc_timer_stw,
5641 _gc_tracer_stw->gc_id());
5642 }
5643
5644 _gc_tracer_stw->report_gc_reference_stats(stats);
5645
5646 // We have completed copying any necessary live referent objects.
5647 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5648
5649 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5650 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5651 }
5652
5653 // Weak Reference processing during an evacuation pause (part 2).
5654 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5655 double ref_enq_start = os::elapsedTime();
5656
5657 ReferenceProcessor* rp = _ref_processor_stw;
5658 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5659
5660 // Now enqueue any remaining on the discovered lists on to
5661 // the pending list.
5662 if (!rp->processing_is_mt()) {
5663 // Serial reference processing...
5664 rp->enqueue_discovered_references();
5665 } else {
5666 // Parallel reference enqueueing
5667
5668 assert(no_of_gc_workers == workers()->active_workers(),
5669 "Need to reset active workers");
5670 assert(rp->num_q() == no_of_gc_workers, "sanity");
5671 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5672
5673 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5674 rp->enqueue_discovered_references(&par_task_executor);
5675 }
5676
5677 rp->verify_no_references_recorded();
5678 assert(!rp->discovery_enabled(), "should have been disabled");
5679
5680 // FIXME
5681 // CM's reference processing also cleans up the string and symbol tables.
5682 // Should we do that here also? We could, but it is a serial operation
5683 // and could significantly increase the pause time.
5684
5685 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5686 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5687 }
5688
5689 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5690 _expand_heap_after_alloc_failure = true;
5691 _evacuation_failed = false;
5692
5693 // Should G1EvacuationFailureALot be in effect for this GC?
5694 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5695
5696 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5697
5698 // Disable the hot card cache.
5699 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5700 hot_card_cache->reset_hot_cache_claimed_index();
5701 hot_card_cache->set_use_cache(false);
5702
5703 uint n_workers;
5704 n_workers =
5705 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5706 workers()->active_workers(),
5707 Threads::number_of_non_daemon_threads());
5708 assert(UseDynamicNumberOfGCThreads ||
5709 n_workers == workers()->total_workers(),
5710 "If not dynamic should be using all the workers");
5711 workers()->set_active_workers(n_workers);
5712 set_par_threads(n_workers);
5713
5714 G1ParTask g1_par_task(this, _task_queues);
5715
5716 init_for_evac_failure(NULL);
5717
5718 rem_set()->prepare_for_younger_refs_iterate(true);
5719
5720 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5721 double start_par_time_sec = os::elapsedTime();
5722 double end_par_time_sec;
5723
5724 {
5725 StrongRootsScope srs(this);
5726 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5727 if (g1_policy()->during_initial_mark_pause()) {
5728 ClassLoaderDataGraph::clear_claimed_marks();
5729 }
5730
5731 // The individual threads will set their evac-failure closures.
5732 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5733 // These tasks use ShareHeap::_process_strong_tasks
5734 assert(UseDynamicNumberOfGCThreads ||
5735 workers()->active_workers() == workers()->total_workers(),
5736 "If not dynamic should be using all the workers");
5737 workers()->run_task(&g1_par_task);
5738 end_par_time_sec = os::elapsedTime();
5739
5740 // Closing the inner scope will execute the destructor
5741 // for the StrongRootsScope object. We record the current
5742 // elapsed time before closing the scope so that time
5743 // taken for the SRS destructor is NOT included in the
5744 // reported parallel time.
5745 }
5746
5747 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5748 g1_policy()->phase_times()->record_par_time(par_time_ms);
5749
5750 double code_root_fixup_time_ms =
5751 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5752 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5753
5754 set_par_threads(0);
5755
5756 // Process any discovered reference objects - we have
5757 // to do this _before_ we retire the GC alloc regions
5758 // as we may have to copy some 'reachable' referent
5759 // objects (and their reachable sub-graphs) that were
5760 // not copied during the pause.
5761 process_discovered_references(n_workers);
5762
5763 if (G1StringDedup::is_enabled()) {
5764 G1STWIsAliveClosure is_alive(this);
5765 G1KeepAliveClosure keep_alive(this);
5766 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5767 }
5768
5769 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5770 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5771
5772 // Reset and re-enable the hot card cache.
5773 // Note the counts for the cards in the regions in the
5774 // collection set are reset when the collection set is freed.
5775 hot_card_cache->reset_hot_cache();
5776 hot_card_cache->set_use_cache(true);
5777
5778 purge_code_root_memory();
5779
5780 finalize_for_evac_failure();
5781
5782 if (evacuation_failed()) {
5783 remove_self_forwarding_pointers();
5784
5785 // Reset the G1EvacuationFailureALot counters and flags
5786 // Note: the values are reset only when an actual
5787 // evacuation failure occurs.
5788 NOT_PRODUCT(reset_evacuation_should_fail();)
5789 }
5790
5791 // Enqueue any remaining references remaining on the STW
5792 // reference processor's discovered lists. We need to do
5793 // this after the card table is cleaned (and verified) as
5794 // the act of enqueueing entries on to the pending list
5795 // will log these updates (and dirty their associated
5796 // cards). We need these updates logged to update any
5797 // RSets.
5798 enqueue_discovered_references(n_workers);
5799
5800 redirty_logged_cards();
5801 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5802 }
5803
5804 void G1CollectedHeap::free_region(HeapRegion* hr,
5805 FreeRegionList* free_list,
5806 bool par,
5807 bool locked) {
5808 assert(!hr->is_free(), "the region should not be free");
5809 assert(!hr->is_empty(), "the region should not be empty");
5810 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5811 assert(free_list != NULL, "pre-condition");
5812
5813 if (G1VerifyBitmaps) {
5814 MemRegion mr(hr->bottom(), hr->end());
5815 concurrent_mark()->clearRangePrevBitmap(mr);
5816 }
5817
5818 // Clear the card counts for this region.
5819 // Note: we only need to do this if the region is not young
5820 // (since we don't refine cards in young regions).
5821 if (!hr->is_young()) {
5822 _cg1r->hot_card_cache()->reset_card_counts(hr);
5823 }
5824 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5825 free_list->add_ordered(hr);
5826 }
5827
5828 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5829 FreeRegionList* free_list,
5830 bool par) {
5831 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5832 assert(free_list != NULL, "pre-condition");
5833
5834 size_t hr_capacity = hr->capacity();
5835 // We need to read this before we make the region non-humongous,
5836 // otherwise the information will be gone.
5837 uint last_index = hr->last_hc_index();
5838 hr->clear_humongous();
5839 free_region(hr, free_list, par);
5840
5841 uint i = hr->hrm_index() + 1;
5842 while (i < last_index) {
5843 HeapRegion* curr_hr = region_at(i);
5844 assert(curr_hr->is_continues_humongous(), "invariant");
5845 curr_hr->clear_humongous();
5846 free_region(curr_hr, free_list, par);
5847 i += 1;
5848 }
5849 }
5850
5851 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5852 const HeapRegionSetCount& humongous_regions_removed) {
5853 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5854 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5855 _old_set.bulk_remove(old_regions_removed);
5856 _humongous_set.bulk_remove(humongous_regions_removed);
5857 }
5858
5859 }
5860
5861 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5862 assert(list != NULL, "list can't be null");
5863 if (!list->is_empty()) {
5864 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5865 _hrm.insert_list_into_free_list(list);
5866 }
5867 }
5868
5869 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5870 _allocator->decrease_used(bytes);
5871 }
5872
5873 class G1ParCleanupCTTask : public AbstractGangTask {
5874 G1SATBCardTableModRefBS* _ct_bs;
5875 G1CollectedHeap* _g1h;
5876 HeapRegion* volatile _su_head;
5877 public:
5878 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5879 G1CollectedHeap* g1h) :
5880 AbstractGangTask("G1 Par Cleanup CT Task"),
5881 _ct_bs(ct_bs), _g1h(g1h) { }
5882
5883 void work(uint worker_id) {
5884 HeapRegion* r;
5885 while (r = _g1h->pop_dirty_cards_region()) {
5886 clear_cards(r);
5887 }
5888 }
5889
5890 void clear_cards(HeapRegion* r) {
5891 // Cards of the survivors should have already been dirtied.
5892 if (!r->is_survivor()) {
5893 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5894 }
5895 }
5896 };
5897
5898 #ifndef PRODUCT
5899 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5900 G1CollectedHeap* _g1h;
5901 G1SATBCardTableModRefBS* _ct_bs;
5902 public:
5903 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5904 : _g1h(g1h), _ct_bs(ct_bs) { }
5905 virtual bool doHeapRegion(HeapRegion* r) {
5906 if (r->is_survivor()) {
5907 _g1h->verify_dirty_region(r);
5908 } else {
5909 _g1h->verify_not_dirty_region(r);
5910 }
5911 return false;
5912 }
5913 };
5914
5915 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5916 // All of the region should be clean.
5917 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5918 MemRegion mr(hr->bottom(), hr->end());
5919 ct_bs->verify_not_dirty_region(mr);
5920 }
5921
5922 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5923 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5924 // dirty allocated blocks as they allocate them. The thread that
5925 // retires each region and replaces it with a new one will do a
5926 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5927 // not dirty that area (one less thing to have to do while holding
5928 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5929 // is dirty.
5930 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5931 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5932 if (hr->is_young()) {
5933 ct_bs->verify_g1_young_region(mr);
5934 } else {
5935 ct_bs->verify_dirty_region(mr);
5936 }
5937 }
5938
5939 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5940 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5941 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5942 verify_dirty_region(hr);
5943 }
5944 }
5945
5946 void G1CollectedHeap::verify_dirty_young_regions() {
5947 verify_dirty_young_list(_young_list->first_region());
5948 }
5949
5950 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5951 HeapWord* tams, HeapWord* end) {
5952 guarantee(tams <= end,
5953 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5954 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5955 if (result < end) {
5956 gclog_or_tty->cr();
5957 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5958 bitmap_name, result);
5959 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5960 bitmap_name, tams, end);
5961 return false;
5962 }
5963 return true;
5964 }
5965
5966 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5967 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5968 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5969
5970 HeapWord* bottom = hr->bottom();
5971 HeapWord* ptams = hr->prev_top_at_mark_start();
5972 HeapWord* ntams = hr->next_top_at_mark_start();
5973 HeapWord* end = hr->end();
5974
5975 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5976
5977 bool res_n = true;
5978 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5979 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5980 // if we happen to be in that state.
5981 if (mark_in_progress() || !_cmThread->in_progress()) {
5982 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5983 }
5984 if (!res_p || !res_n) {
5985 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5986 HR_FORMAT_PARAMS(hr));
5987 gclog_or_tty->print_cr("#### Caller: %s", caller);
5988 return false;
5989 }
5990 return true;
5991 }
5992
5993 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5994 if (!G1VerifyBitmaps) return;
5995
5996 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5997 }
5998
5999 class G1VerifyBitmapClosure : public HeapRegionClosure {
6000 private:
6001 const char* _caller;
6002 G1CollectedHeap* _g1h;
6003 bool _failures;
6004
6005 public:
6006 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6007 _caller(caller), _g1h(g1h), _failures(false) { }
6008
6009 bool failures() { return _failures; }
6010
6011 virtual bool doHeapRegion(HeapRegion* hr) {
6012 if (hr->is_continues_humongous()) return false;
6013
6014 bool result = _g1h->verify_bitmaps(_caller, hr);
6015 if (!result) {
6016 _failures = true;
6017 }
6018 return false;
6019 }
6020 };
6021
6022 void G1CollectedHeap::check_bitmaps(const char* caller) {
6023 if (!G1VerifyBitmaps) return;
6024
6025 G1VerifyBitmapClosure cl(caller, this);
6026 heap_region_iterate(&cl);
6027 guarantee(!cl.failures(), "bitmap verification");
6028 }
6029 #endif // PRODUCT
6030
6031 void G1CollectedHeap::cleanUpCardTable() {
6032 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6033 double start = os::elapsedTime();
6034
6035 {
6036 // Iterate over the dirty cards region list.
6037 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6038
6039 set_par_threads();
6040 workers()->run_task(&cleanup_task);
6041 set_par_threads(0);
6042 #ifndef PRODUCT
6043 if (G1VerifyCTCleanup || VerifyAfterGC) {
6044 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6045 heap_region_iterate(&cleanup_verifier);
6046 }
6047 #endif
6048 }
6049
6050 double elapsed = os::elapsedTime() - start;
6051 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6052 }
6053
6054 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6055 size_t pre_used = 0;
6056 FreeRegionList local_free_list("Local List for CSet Freeing");
6057
6058 double young_time_ms = 0.0;
6059 double non_young_time_ms = 0.0;
6060
6061 // Since the collection set is a superset of the the young list,
6062 // all we need to do to clear the young list is clear its
6063 // head and length, and unlink any young regions in the code below
6064 _young_list->clear();
6065
6066 G1CollectorPolicy* policy = g1_policy();
6067
6068 double start_sec = os::elapsedTime();
6069 bool non_young = true;
6070
6071 HeapRegion* cur = cs_head;
6072 int age_bound = -1;
6073 size_t rs_lengths = 0;
6074
6075 while (cur != NULL) {
6076 assert(!is_on_master_free_list(cur), "sanity");
6077 if (non_young) {
6078 if (cur->is_young()) {
6079 double end_sec = os::elapsedTime();
6080 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6081 non_young_time_ms += elapsed_ms;
6082
6083 start_sec = os::elapsedTime();
6084 non_young = false;
6085 }
6086 } else {
6087 if (!cur->is_young()) {
6088 double end_sec = os::elapsedTime();
6089 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6090 young_time_ms += elapsed_ms;
6091
6092 start_sec = os::elapsedTime();
6093 non_young = true;
6094 }
6095 }
6096
6097 rs_lengths += cur->rem_set()->occupied_locked();
6098
6099 HeapRegion* next = cur->next_in_collection_set();
6100 assert(cur->in_collection_set(), "bad CS");
6101 cur->set_next_in_collection_set(NULL);
6102 cur->set_in_collection_set(false);
6103
6104 if (cur->is_young()) {
6105 int index = cur->young_index_in_cset();
6106 assert(index != -1, "invariant");
6107 assert((uint) index < policy->young_cset_region_length(), "invariant");
6108 size_t words_survived = _surviving_young_words[index];
6109 cur->record_surv_words_in_group(words_survived);
6110
6111 // At this point the we have 'popped' cur from the collection set
6112 // (linked via next_in_collection_set()) but it is still in the
6113 // young list (linked via next_young_region()). Clear the
6114 // _next_young_region field.
6115 cur->set_next_young_region(NULL);
6116 } else {
6117 int index = cur->young_index_in_cset();
6118 assert(index == -1, "invariant");
6119 }
6120
6121 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6122 (!cur->is_young() && cur->young_index_in_cset() == -1),
6123 "invariant" );
6124
6125 if (!cur->evacuation_failed()) {
6126 MemRegion used_mr = cur->used_region();
6127
6128 // And the region is empty.
6129 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6130 pre_used += cur->used();
6131 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6132 } else {
6133 cur->uninstall_surv_rate_group();
6134 if (cur->is_young()) {
6135 cur->set_young_index_in_cset(-1);
6136 }
6137 cur->set_evacuation_failed(false);
6138 // The region is now considered to be old.
6139 cur->set_old();
6140 _old_set.add(cur);
6141 evacuation_info.increment_collectionset_used_after(cur->used());
6142 }
6143 cur = next;
6144 }
6145
6146 evacuation_info.set_regions_freed(local_free_list.length());
6147 policy->record_max_rs_lengths(rs_lengths);
6148 policy->cset_regions_freed();
6149
6150 double end_sec = os::elapsedTime();
6151 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6152
6153 if (non_young) {
6154 non_young_time_ms += elapsed_ms;
6155 } else {
6156 young_time_ms += elapsed_ms;
6157 }
6158
6159 prepend_to_freelist(&local_free_list);
6160 decrement_summary_bytes(pre_used);
6161 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6162 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6163 }
6164
6165 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6166 private:
6167 FreeRegionList* _free_region_list;
6168 HeapRegionSet* _proxy_set;
6169 HeapRegionSetCount _humongous_regions_removed;
6170 size_t _freed_bytes;
6171 public:
6172
6173 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6174 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6175 }
6176
6177 virtual bool doHeapRegion(HeapRegion* r) {
6178 if (!r->is_starts_humongous()) {
6179 return false;
6180 }
6181
6182 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6183
6184 oop obj = (oop)r->bottom();
6185 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6186
6187 // The following checks whether the humongous object is live are sufficient.
6188 // The main additional check (in addition to having a reference from the roots
6189 // or the young gen) is whether the humongous object has a remembered set entry.
6190 //
6191 // A humongous object cannot be live if there is no remembered set for it
6192 // because:
6193 // - there can be no references from within humongous starts regions referencing
6194 // the object because we never allocate other objects into them.
6195 // (I.e. there are no intra-region references that may be missed by the
6196 // remembered set)
6197 // - as soon there is a remembered set entry to the humongous starts region
6198 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6199 // until the end of a concurrent mark.
6200 //
6201 // It is not required to check whether the object has been found dead by marking
6202 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6203 // all objects allocated during that time are considered live.
6204 // SATB marking is even more conservative than the remembered set.
6205 // So if at this point in the collection there is no remembered set entry,
6206 // nobody has a reference to it.
6207 // At the start of collection we flush all refinement logs, and remembered sets
6208 // are completely up-to-date wrt to references to the humongous object.
6209 //
6210 // Other implementation considerations:
6211 // - never consider object arrays: while they are a valid target, they have not
6212 // been observed to be used as temporary objects.
6213 // - they would also pose considerable effort for cleaning up the the remembered
6214 // sets.
6215 // While this cleanup is not strictly necessary to be done (or done instantly),
6216 // given that their occurrence is very low, this saves us this additional
6217 // complexity.
6218 uint region_idx = r->hrm_index();
6219 if (g1h->humongous_is_live(region_idx) ||
6220 g1h->humongous_region_is_always_live(region_idx)) {
6221
6222 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6223 gclog_or_tty->print_cr("Live humongous %d region %d size "SIZE_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6224 r->is_humongous(),
6225 region_idx,
6226 obj->size()*HeapWordSize,
6227 r->rem_set()->occupied(),
6228 r->rem_set()->strong_code_roots_list_length(),
6229 next_bitmap->isMarked(r->bottom()),
6230 g1h->humongous_is_live(region_idx),
6231 obj->is_objArray()
6232 );
6233 }
6234
6235 return false;
6236 }
6237
6238 guarantee(!obj->is_objArray(),
6239 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6240 r->bottom()));
6241
6242 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6243 gclog_or_tty->print_cr("Reclaim humongous region %d size "SIZE_FORMAT" start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6244 r->is_humongous(),
6245 obj->size()*HeapWordSize,
6246 r->bottom(),
6247 region_idx,
6248 r->region_num(),
6249 r->rem_set()->occupied(),
6250 r->rem_set()->strong_code_roots_list_length(),
6251 next_bitmap->isMarked(r->bottom()),
6252 g1h->humongous_is_live(region_idx),
6253 obj->is_objArray()
6254 );
6255 }
6256 // Need to clear mark bit of the humongous object if already set.
6257 if (next_bitmap->isMarked(r->bottom())) {
6258 next_bitmap->clear(r->bottom());
6259 }
6260 _freed_bytes += r->used();
6261 r->set_containing_set(NULL);
6262 _humongous_regions_removed.increment(1u, r->capacity());
6263 g1h->free_humongous_region(r, _free_region_list, false);
6264
6265 return false;
6266 }
6267
6268 HeapRegionSetCount& humongous_free_count() {
6269 return _humongous_regions_removed;
6270 }
6271
6272 size_t bytes_freed() const {
6273 return _freed_bytes;
6274 }
6275
6276 size_t humongous_reclaimed() const {
6277 return _humongous_regions_removed.length();
6278 }
6279 };
6280
6281 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6282 assert_at_safepoint(true);
6283
6284 if (!G1ReclaimDeadHumongousObjectsAtYoungGC ||
6285 (!_has_humongous_reclaim_candidates && !G1TraceReclaimDeadHumongousObjectsAtYoungGC)) {
6286 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6287 return;
6288 }
6289
6290 double start_time = os::elapsedTime();
6291
6292 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6293
6294 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6295 heap_region_iterate(&cl);
6296
6297 HeapRegionSetCount empty_set;
6298 remove_from_old_sets(empty_set, cl.humongous_free_count());
6299
6300 G1HRPrinter* hr_printer = _g1h->hr_printer();
6301 if (hr_printer->is_active()) {
6302 FreeRegionListIterator iter(&local_cleanup_list);
6303 while (iter.more_available()) {
6304 HeapRegion* hr = iter.get_next();
6305 hr_printer->cleanup(hr);
6306 }
6307 }
6308
6309 prepend_to_freelist(&local_cleanup_list);
6310 decrement_summary_bytes(cl.bytes_freed());
6311
6312 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6313 cl.humongous_reclaimed());
6314 }
6315
6316 // This routine is similar to the above but does not record
6317 // any policy statistics or update free lists; we are abandoning
6318 // the current incremental collection set in preparation of a
6319 // full collection. After the full GC we will start to build up
6320 // the incremental collection set again.
6321 // This is only called when we're doing a full collection
6322 // and is immediately followed by the tearing down of the young list.
6323
6324 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6325 HeapRegion* cur = cs_head;
6326
6327 while (cur != NULL) {
6328 HeapRegion* next = cur->next_in_collection_set();
6329 assert(cur->in_collection_set(), "bad CS");
6330 cur->set_next_in_collection_set(NULL);
6331 cur->set_in_collection_set(false);
6332 cur->set_young_index_in_cset(-1);
6333 cur = next;
6334 }
6335 }
6336
6337 void G1CollectedHeap::set_free_regions_coming() {
6338 if (G1ConcRegionFreeingVerbose) {
6339 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6340 "setting free regions coming");
6341 }
6342
6343 assert(!free_regions_coming(), "pre-condition");
6344 _free_regions_coming = true;
6345 }
6346
6347 void G1CollectedHeap::reset_free_regions_coming() {
6348 assert(free_regions_coming(), "pre-condition");
6349
6350 {
6351 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6352 _free_regions_coming = false;
6353 SecondaryFreeList_lock->notify_all();
6354 }
6355
6356 if (G1ConcRegionFreeingVerbose) {
6357 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6358 "reset free regions coming");
6359 }
6360 }
6361
6362 void G1CollectedHeap::wait_while_free_regions_coming() {
6363 // Most of the time we won't have to wait, so let's do a quick test
6364 // first before we take the lock.
6365 if (!free_regions_coming()) {
6366 return;
6367 }
6368
6369 if (G1ConcRegionFreeingVerbose) {
6370 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6371 "waiting for free regions");
6372 }
6373
6374 {
6375 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6376 while (free_regions_coming()) {
6377 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6378 }
6379 }
6380
6381 if (G1ConcRegionFreeingVerbose) {
6382 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6383 "done waiting for free regions");
6384 }
6385 }
6386
6387 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6388 assert(heap_lock_held_for_gc(),
6389 "the heap lock should already be held by or for this thread");
6390 _young_list->push_region(hr);
6391 }
6392
6393 class NoYoungRegionsClosure: public HeapRegionClosure {
6394 private:
6395 bool _success;
6396 public:
6397 NoYoungRegionsClosure() : _success(true) { }
6398 bool doHeapRegion(HeapRegion* r) {
6399 if (r->is_young()) {
6400 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6401 r->bottom(), r->end());
6402 _success = false;
6403 }
6404 return false;
6405 }
6406 bool success() { return _success; }
6407 };
6408
6409 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6410 bool ret = _young_list->check_list_empty(check_sample);
6411
6412 if (check_heap) {
6413 NoYoungRegionsClosure closure;
6414 heap_region_iterate(&closure);
6415 ret = ret && closure.success();
6416 }
6417
6418 return ret;
6419 }
6420
6421 class TearDownRegionSetsClosure : public HeapRegionClosure {
6422 private:
6423 HeapRegionSet *_old_set;
6424
6425 public:
6426 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6427
6428 bool doHeapRegion(HeapRegion* r) {
6429 if (r->is_old()) {
6430 _old_set->remove(r);
6431 } else {
6432 // We ignore free regions, we'll empty the free list afterwards.
6433 // We ignore young regions, we'll empty the young list afterwards.
6434 // We ignore humongous regions, we're not tearing down the
6435 // humongous regions set.
6436 assert(r->is_free() || r->is_young() || r->is_humongous(),
6437 "it cannot be another type");
6438 }
6439 return false;
6440 }
6441
6442 ~TearDownRegionSetsClosure() {
6443 assert(_old_set->is_empty(), "post-condition");
6444 }
6445 };
6446
6447 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6448 assert_at_safepoint(true /* should_be_vm_thread */);
6449
6450 if (!free_list_only) {
6451 TearDownRegionSetsClosure cl(&_old_set);
6452 heap_region_iterate(&cl);
6453
6454 // Note that emptying the _young_list is postponed and instead done as
6455 // the first step when rebuilding the regions sets again. The reason for
6456 // this is that during a full GC string deduplication needs to know if
6457 // a collected region was young or old when the full GC was initiated.
6458 }
6459 _hrm.remove_all_free_regions();
6460 }
6461
6462 class RebuildRegionSetsClosure : public HeapRegionClosure {
6463 private:
6464 bool _free_list_only;
6465 HeapRegionSet* _old_set;
6466 HeapRegionManager* _hrm;
6467 size_t _total_used;
6468
6469 public:
6470 RebuildRegionSetsClosure(bool free_list_only,
6471 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6472 _free_list_only(free_list_only),
6473 _old_set(old_set), _hrm(hrm), _total_used(0) {
6474 assert(_hrm->num_free_regions() == 0, "pre-condition");
6475 if (!free_list_only) {
6476 assert(_old_set->is_empty(), "pre-condition");
6477 }
6478 }
6479
6480 bool doHeapRegion(HeapRegion* r) {
6481 if (r->is_continues_humongous()) {
6482 return false;
6483 }
6484
6485 if (r->is_empty()) {
6486 // Add free regions to the free list
6487 r->set_free();
6488 r->set_allocation_context(AllocationContext::system());
6489 _hrm->insert_into_free_list(r);
6490 } else if (!_free_list_only) {
6491 assert(!r->is_young(), "we should not come across young regions");
6492
6493 if (r->is_humongous()) {
6494 // We ignore humongous regions, we left the humongous set unchanged
6495 } else {
6496 // Objects that were compacted would have ended up on regions
6497 // that were previously old or free.
6498 assert(r->is_free() || r->is_old(), "invariant");
6499 // We now consider them old, so register as such.
6500 r->set_old();
6501 _old_set->add(r);
6502 }
6503 _total_used += r->used();
6504 }
6505
6506 return false;
6507 }
6508
6509 size_t total_used() {
6510 return _total_used;
6511 }
6512 };
6513
6514 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6515 assert_at_safepoint(true /* should_be_vm_thread */);
6516
6517 if (!free_list_only) {
6518 _young_list->empty_list();
6519 }
6520
6521 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6522 heap_region_iterate(&cl);
6523
6524 if (!free_list_only) {
6525 _allocator->set_used(cl.total_used());
6526 }
6527 assert(_allocator->used_unlocked() == recalculate_used(),
6528 err_msg("inconsistent _allocator->used_unlocked(), "
6529 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6530 _allocator->used_unlocked(), recalculate_used()));
6531 }
6532
6533 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6534 _refine_cte_cl->set_concurrent(concurrent);
6535 }
6536
6537 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6538 HeapRegion* hr = heap_region_containing(p);
6539 return hr->is_in(p);
6540 }
6541
6542 // Methods for the mutator alloc region
6543
6544 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6545 bool force) {
6546 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6547 assert(!force || g1_policy()->can_expand_young_list(),
6548 "if force is true we should be able to expand the young list");
6549 bool young_list_full = g1_policy()->is_young_list_full();
6550 if (force || !young_list_full) {
6551 HeapRegion* new_alloc_region = new_region(word_size,
6552 false /* is_old */,
6553 false /* do_expand */);
6554 if (new_alloc_region != NULL) {
6555 set_region_short_lived_locked(new_alloc_region);
6556 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6557 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6558 return new_alloc_region;
6559 }
6560 }
6561 return NULL;
6562 }
6563
6564 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6565 size_t allocated_bytes) {
6566 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6567 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6568
6569 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6570 _allocator->increase_used(allocated_bytes);
6571 _hr_printer.retire(alloc_region);
6572 // We update the eden sizes here, when the region is retired,
6573 // instead of when it's allocated, since this is the point that its
6574 // used space has been recored in _summary_bytes_used.
6575 g1mm()->update_eden_size();
6576 }
6577
6578 void G1CollectedHeap::set_par_threads() {
6579 // Don't change the number of workers. Use the value previously set
6580 // in the workgroup.
6581 uint n_workers = workers()->active_workers();
6582 assert(UseDynamicNumberOfGCThreads ||
6583 n_workers == workers()->total_workers(),
6584 "Otherwise should be using the total number of workers");
6585 if (n_workers == 0) {
6586 assert(false, "Should have been set in prior evacuation pause.");
6587 n_workers = ParallelGCThreads;
6588 workers()->set_active_workers(n_workers);
6589 }
6590 set_par_threads(n_workers);
6591 }
6592
6593 // Methods for the GC alloc regions
6594
6595 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6596 uint count,
6597 GCAllocPurpose ap) {
6598 assert(FreeList_lock->owned_by_self(), "pre-condition");
6599
6600 if (count < g1_policy()->max_regions(ap)) {
6601 bool survivor = (ap == GCAllocForSurvived);
6602 HeapRegion* new_alloc_region = new_region(word_size,
6603 !survivor,
6604 true /* do_expand */);
6605 if (new_alloc_region != NULL) {
6606 // We really only need to do this for old regions given that we
6607 // should never scan survivors. But it doesn't hurt to do it
6608 // for survivors too.
6609 new_alloc_region->record_top_and_timestamp();
6610 if (survivor) {
6611 new_alloc_region->set_survivor();
6612 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6613 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6614 } else {
6615 new_alloc_region->set_old();
6616 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6617 check_bitmaps("Old Region Allocation", new_alloc_region);
6618 }
6619 bool during_im = g1_policy()->during_initial_mark_pause();
6620 new_alloc_region->note_start_of_copying(during_im);
6621 return new_alloc_region;
6622 } else {
6623 g1_policy()->note_alloc_region_limit_reached(ap);
6624 }
6625 }
6626 return NULL;
6627 }
6628
6629 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6630 size_t allocated_bytes,
6631 GCAllocPurpose ap) {
6632 bool during_im = g1_policy()->during_initial_mark_pause();
6633 alloc_region->note_end_of_copying(during_im);
6634 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6635 if (ap == GCAllocForSurvived) {
6636 young_list()->add_survivor_region(alloc_region);
6637 } else {
6638 _old_set.add(alloc_region);
6639 }
6640 _hr_printer.retire(alloc_region);
6641 }
6642
6643 // Heap region set verification
6644
6645 class VerifyRegionListsClosure : public HeapRegionClosure {
6646 private:
6647 HeapRegionSet* _old_set;
6648 HeapRegionSet* _humongous_set;
6649 HeapRegionManager* _hrm;
6650
6651 public:
6652 HeapRegionSetCount _old_count;
6653 HeapRegionSetCount _humongous_count;
6654 HeapRegionSetCount _free_count;
6655
6656 VerifyRegionListsClosure(HeapRegionSet* old_set,
6657 HeapRegionSet* humongous_set,
6658 HeapRegionManager* hrm) :
6659 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6660 _old_count(), _humongous_count(), _free_count(){ }
6661
6662 bool doHeapRegion(HeapRegion* hr) {
6663 if (hr->is_continues_humongous()) {
6664 return false;
6665 }
6666
6667 if (hr->is_young()) {
6668 // TODO
6669 } else if (hr->is_starts_humongous()) {
6670 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6671 _humongous_count.increment(1u, hr->capacity());
6672 } else if (hr->is_empty()) {
6673 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6674 _free_count.increment(1u, hr->capacity());
6675 } else if (hr->is_old()) {
6676 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6677 _old_count.increment(1u, hr->capacity());
6678 } else {
6679 ShouldNotReachHere();
6680 }
6681 return false;
6682 }
6683
6684 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6685 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6686 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6687 old_set->total_capacity_bytes(), _old_count.capacity()));
6688
6689 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6690 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6691 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6692
6693 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()));
6694 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6695 free_list->total_capacity_bytes(), _free_count.capacity()));
6696 }
6697 };
6698
6699 void G1CollectedHeap::verify_region_sets() {
6700 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6701
6702 // First, check the explicit lists.
6703 _hrm.verify();
6704 {
6705 // Given that a concurrent operation might be adding regions to
6706 // the secondary free list we have to take the lock before
6707 // verifying it.
6708 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6709 _secondary_free_list.verify_list();
6710 }
6711
6712 // If a concurrent region freeing operation is in progress it will
6713 // be difficult to correctly attributed any free regions we come
6714 // across to the correct free list given that they might belong to
6715 // one of several (free_list, secondary_free_list, any local lists,
6716 // etc.). So, if that's the case we will skip the rest of the
6717 // verification operation. Alternatively, waiting for the concurrent
6718 // operation to complete will have a non-trivial effect on the GC's
6719 // operation (no concurrent operation will last longer than the
6720 // interval between two calls to verification) and it might hide
6721 // any issues that we would like to catch during testing.
6722 if (free_regions_coming()) {
6723 return;
6724 }
6725
6726 // Make sure we append the secondary_free_list on the free_list so
6727 // that all free regions we will come across can be safely
6728 // attributed to the free_list.
6729 append_secondary_free_list_if_not_empty_with_lock();
6730
6731 // Finally, make sure that the region accounting in the lists is
6732 // consistent with what we see in the heap.
6733
6734 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6735 heap_region_iterate(&cl);
6736 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6737 }
6738
6739 // Optimized nmethod scanning
6740
6741 class RegisterNMethodOopClosure: public OopClosure {
6742 G1CollectedHeap* _g1h;
6743 nmethod* _nm;
6744
6745 template <class T> void do_oop_work(T* p) {
6746 T heap_oop = oopDesc::load_heap_oop(p);
6747 if (!oopDesc::is_null(heap_oop)) {
6748 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6749 HeapRegion* hr = _g1h->heap_region_containing(obj);
6750 assert(!hr->is_continues_humongous(),
6751 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6752 " starting at "HR_FORMAT,
6753 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6754
6755 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6756 hr->add_strong_code_root_locked(_nm);
6757 }
6758 }
6759
6760 public:
6761 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6762 _g1h(g1h), _nm(nm) {}
6763
6764 void do_oop(oop* p) { do_oop_work(p); }
6765 void do_oop(narrowOop* p) { do_oop_work(p); }
6766 };
6767
6768 class UnregisterNMethodOopClosure: public OopClosure {
6769 G1CollectedHeap* _g1h;
6770 nmethod* _nm;
6771
6772 template <class T> void do_oop_work(T* p) {
6773 T heap_oop = oopDesc::load_heap_oop(p);
6774 if (!oopDesc::is_null(heap_oop)) {
6775 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6776 HeapRegion* hr = _g1h->heap_region_containing(obj);
6777 assert(!hr->is_continues_humongous(),
6778 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6779 " starting at "HR_FORMAT,
6780 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6781
6782 hr->remove_strong_code_root(_nm);
6783 }
6784 }
6785
6786 public:
6787 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6788 _g1h(g1h), _nm(nm) {}
6789
6790 void do_oop(oop* p) { do_oop_work(p); }
6791 void do_oop(narrowOop* p) { do_oop_work(p); }
6792 };
6793
6794 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6795 CollectedHeap::register_nmethod(nm);
6796
6797 guarantee(nm != NULL, "sanity");
6798 RegisterNMethodOopClosure reg_cl(this, nm);
6799 nm->oops_do(®_cl);
6800 }
6801
6802 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6803 CollectedHeap::unregister_nmethod(nm);
6804
6805 guarantee(nm != NULL, "sanity");
6806 UnregisterNMethodOopClosure reg_cl(this, nm);
6807 nm->oops_do(®_cl, true);
6808 }
6809
6810 void G1CollectedHeap::purge_code_root_memory() {
6811 double purge_start = os::elapsedTime();
6812 G1CodeRootSet::purge();
6813 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6814 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6815 }
6816
6817 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6818 G1CollectedHeap* _g1h;
6819
6820 public:
6821 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6822 _g1h(g1h) {}
6823
6824 void do_code_blob(CodeBlob* cb) {
6825 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6826 if (nm == NULL) {
6827 return;
6828 }
6829
6830 if (ScavengeRootsInCode) {
6831 _g1h->register_nmethod(nm);
6832 }
6833 }
6834 };
6835
6836 void G1CollectedHeap::rebuild_strong_code_roots() {
6837 RebuildStrongCodeRootClosure blob_cl(this);
6838 CodeCache::blobs_do(&blob_cl);
6839 }