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