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