1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/stringTable.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "gc_implementation/g1/bufferingOopClosure.hpp"
35 #include "gc_implementation/g1/concurrentG1Refine.hpp"
36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
40 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
41 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
42 #include "gc_implementation/g1/g1EvacFailure.hpp"
43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
44 #include "gc_implementation/g1/g1Log.hpp"
45 #include "gc_implementation/g1/g1MarkSweep.hpp"
46 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
47 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
48 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
49 #include "gc_implementation/g1/g1RemSet.inline.hpp"
50 #include "gc_implementation/g1/g1StringDedup.hpp"
51 #include "gc_implementation/g1/g1YCTypes.hpp"
52 #include "gc_implementation/g1/heapRegion.inline.hpp"
53 #include "gc_implementation/g1/heapRegionRemSet.hpp"
54 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
55 #include "gc_implementation/g1/vm_operations_g1.hpp"
56 #include "gc_implementation/shared/gcHeapSummary.hpp"
57 #include "gc_implementation/shared/gcTimer.hpp"
58 #include "gc_implementation/shared/gcTrace.hpp"
59 #include "gc_implementation/shared/gcTraceTime.hpp"
60 #include "gc_implementation/shared/isGCActiveMark.hpp"
61 #include "memory/allocation.hpp"
62 #include "memory/gcLocker.inline.hpp"
63 #include "memory/generationSpec.hpp"
64 #include "memory/iterator.hpp"
65 #include "memory/referenceProcessor.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "oops/oop.pcgc.inline.hpp"
68 #include "runtime/atomic.inline.hpp"
69 #include "runtime/orderAccess.inline.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "utilities/globalDefinitions.hpp"
72
73 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
74
75 // turn it on so that the contents of the young list (scan-only /
76 // to-be-collected) are printed at "strategic" points before / during
77 // / after the collection --- this is useful for debugging
78 #define YOUNG_LIST_VERBOSE 0
79 // CURRENT STATUS
80 // This file is under construction. Search for "FIXME".
81
82 // INVARIANTS/NOTES
83 //
84 // All allocation activity covered by the G1CollectedHeap interface is
85 // serialized by acquiring the HeapLock. This happens in mem_allocate
86 // and allocate_new_tlab, which are the "entry" points to the
87 // allocation code from the rest of the JVM. (Note that this does not
88 // apply to TLAB allocation, which is not part of this interface: it
89 // is done by clients of this interface.)
90
91 // Notes on implementation of parallelism in different tasks.
92 //
93 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism.
94 // The number of GC workers is passed to heap_region_par_iterate().
95 // It does use run_task() which sets _n_workers in the task.
96 // G1ParTask executes g1_process_roots() ->
97 // SharedHeap::process_roots() which calls eventually to
98 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
99 // SequentialSubTasksDone. SharedHeap::process_roots() also
100 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
101 //
102
103 // Local to this file.
104
105 class RefineCardTableEntryClosure: public CardTableEntryClosure {
106 bool _concurrent;
107 public:
108 RefineCardTableEntryClosure() : _concurrent(true) { }
109
110 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
111 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
112 // This path is executed by the concurrent refine or mutator threads,
113 // concurrently, and so we do not care if card_ptr contains references
114 // that point into the collection set.
115 assert(!oops_into_cset, "should be");
116
117 if (_concurrent && SuspendibleThreadSet::should_yield()) {
118 // Caller will actually yield.
119 return false;
120 }
121 // Otherwise, we finished successfully; return true.
122 return true;
123 }
124
125 void set_concurrent(bool b) { _concurrent = b; }
126 };
127
128
129 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
130 size_t _num_processed;
131 CardTableModRefBS* _ctbs;
132 int _histo[256];
133
134 public:
135 ClearLoggedCardTableEntryClosure() :
136 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
137 {
138 for (int i = 0; i < 256; i++) _histo[i] = 0;
139 }
140
141 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
142 unsigned char* ujb = (unsigned char*)card_ptr;
143 int ind = (int)(*ujb);
144 _histo[ind]++;
145
146 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
147 _num_processed++;
148
149 return true;
150 }
151
152 size_t num_processed() { return _num_processed; }
153
154 void print_histo() {
155 gclog_or_tty->print_cr("Card table value histogram:");
156 for (int i = 0; i < 256; i++) {
157 if (_histo[i] != 0) {
158 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
159 }
160 }
161 }
162 };
163
164 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
165 private:
166 size_t _num_processed;
167
168 public:
169 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
170
171 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
172 *card_ptr = CardTableModRefBS::dirty_card_val();
173 _num_processed++;
174 return true;
175 }
176
177 size_t num_processed() const { return _num_processed; }
178 };
179
180 YoungList::YoungList(G1CollectedHeap* g1h) :
181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
183 guarantee(check_list_empty(false), "just making sure...");
184 }
185
186 void YoungList::push_region(HeapRegion *hr) {
187 assert(!hr->is_young(), "should not already be young");
188 assert(hr->get_next_young_region() == NULL, "cause it should!");
189
190 hr->set_next_young_region(_head);
191 _head = hr;
192
193 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
194 ++_length;
195 }
196
197 void YoungList::add_survivor_region(HeapRegion* hr) {
198 assert(hr->is_survivor(), "should be flagged as survivor region");
199 assert(hr->get_next_young_region() == NULL, "cause it should!");
200
201 hr->set_next_young_region(_survivor_head);
202 if (_survivor_head == NULL) {
203 _survivor_tail = hr;
204 }
205 _survivor_head = hr;
206 ++_survivor_length;
207 }
208
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 // This is called before a Full GC and all the non-empty /
215 // non-humongous regions at the end of the Full GC will end up as
216 // old anyway.
217 list->set_old();
218 list = next;
219 }
220 }
221
222 void YoungList::empty_list() {
223 assert(check_list_well_formed(), "young list should be well formed");
224
225 empty_list(_head);
226 _head = NULL;
227 _length = 0;
228
229 empty_list(_survivor_head);
230 _survivor_head = NULL;
231 _survivor_tail = NULL;
232 _survivor_length = 0;
233
234 _last_sampled_rs_lengths = 0;
235
236 assert(check_list_empty(false), "just making sure...");
237 }
238
239 bool YoungList::check_list_well_formed() {
240 bool ret = true;
241
242 uint length = 0;
243 HeapRegion* curr = _head;
244 HeapRegion* last = NULL;
245 while (curr != NULL) {
246 if (!curr->is_young()) {
247 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
248 "incorrectly tagged (y: %d, surv: %d)",
249 curr->bottom(), curr->end(),
250 curr->is_young(), curr->is_survivor());
251 ret = false;
252 }
253 ++length;
254 last = curr;
255 curr = curr->get_next_young_region();
256 }
257 ret = ret && (length == _length);
258
259 if (!ret) {
260 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
261 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
262 length, _length);
263 }
264
265 return ret;
266 }
267
268 bool YoungList::check_list_empty(bool check_sample) {
269 bool ret = true;
270
271 if (_length != 0) {
272 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
273 _length);
274 ret = false;
275 }
276 if (check_sample && _last_sampled_rs_lengths != 0) {
277 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
278 ret = false;
279 }
280 if (_head != NULL) {
281 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
282 ret = false;
283 }
284 if (!ret) {
285 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
286 }
287
288 return ret;
289 }
290
291 void
292 YoungList::rs_length_sampling_init() {
293 _sampled_rs_lengths = 0;
294 _curr = _head;
295 }
296
297 bool
298 YoungList::rs_length_sampling_more() {
299 return _curr != NULL;
300 }
301
302 void
303 YoungList::rs_length_sampling_next() {
304 assert( _curr != NULL, "invariant" );
305 size_t rs_length = _curr->rem_set()->occupied();
306
307 _sampled_rs_lengths += rs_length;
308
309 // The current region may not yet have been added to the
310 // incremental collection set (it gets added when it is
311 // retired as the current allocation region).
312 if (_curr->in_collection_set()) {
313 // Update the collection set policy information for this region
314 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
315 }
316
317 _curr = _curr->get_next_young_region();
318 if (_curr == NULL) {
319 _last_sampled_rs_lengths = _sampled_rs_lengths;
320 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
321 }
322 }
323
324 void
325 YoungList::reset_auxilary_lists() {
326 guarantee( is_empty(), "young list should be empty" );
327 assert(check_list_well_formed(), "young list should be well formed");
328
329 // Add survivor regions to SurvRateGroup.
330 _g1h->g1_policy()->note_start_adding_survivor_regions();
331 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
332
333 int young_index_in_cset = 0;
334 for (HeapRegion* curr = _survivor_head;
335 curr != NULL;
336 curr = curr->get_next_young_region()) {
337 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
338
339 // The region is a non-empty survivor so let's add it to
340 // the incremental collection set for the next evacuation
341 // pause.
342 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
343 young_index_in_cset += 1;
344 }
345 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
346 _g1h->g1_policy()->note_stop_adding_survivor_regions();
347
348 _head = _survivor_head;
349 _length = _survivor_length;
350 if (_survivor_head != NULL) {
351 assert(_survivor_tail != NULL, "cause it shouldn't be");
352 assert(_survivor_length > 0, "invariant");
353 _survivor_tail->set_next_young_region(NULL);
354 }
355
356 // Don't clear the survivor list handles until the start of
357 // the next evacuation pause - we need it in order to re-tag
358 // the survivor regions from this evacuation pause as 'young'
359 // at the start of the next.
360
361 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
362
363 assert(check_list_well_formed(), "young list should be well formed");
364 }
365
366 void YoungList::print() {
367 HeapRegion* lists[] = {_head, _survivor_head};
368 const char* names[] = {"YOUNG", "SURVIVOR"};
369
370 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
371 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
372 HeapRegion *curr = lists[list];
373 if (curr == NULL)
374 gclog_or_tty->print_cr(" empty");
375 while (curr != NULL) {
376 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
377 HR_FORMAT_PARAMS(curr),
378 curr->prev_top_at_mark_start(),
379 curr->next_top_at_mark_start(),
380 curr->age_in_surv_rate_group_cond());
381 curr = curr->get_next_young_region();
382 }
383 }
384
385 gclog_or_tty->cr();
386 }
387
388 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
389 OtherRegionsTable::invalidate(start_idx, num_regions);
390 }
391
392 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
393 reset_from_card_cache(start_idx, num_regions);
394 }
395
396 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
397 {
398 // Claim the right to put the region on the dirty cards region list
399 // by installing a self pointer.
400 HeapRegion* next = hr->get_next_dirty_cards_region();
401 if (next == NULL) {
402 HeapRegion* res = (HeapRegion*)
403 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
404 NULL);
405 if (res == NULL) {
406 HeapRegion* head;
407 do {
408 // Put the region to the dirty cards region list.
409 head = _dirty_cards_region_list;
410 next = (HeapRegion*)
411 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
412 if (next == head) {
413 assert(hr->get_next_dirty_cards_region() == hr,
414 "hr->get_next_dirty_cards_region() != hr");
415 if (next == NULL) {
416 // The last region in the list points to itself.
417 hr->set_next_dirty_cards_region(hr);
418 } else {
419 hr->set_next_dirty_cards_region(next);
420 }
421 }
422 } while (next != head);
423 }
424 }
425 }
426
427 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
428 {
429 HeapRegion* head;
430 HeapRegion* hr;
431 do {
432 head = _dirty_cards_region_list;
433 if (head == NULL) {
434 return NULL;
435 }
436 HeapRegion* new_head = head->get_next_dirty_cards_region();
437 if (head == new_head) {
438 // The last region.
439 new_head = NULL;
440 }
441 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
442 head);
443 } while (hr != head);
444 assert(hr != NULL, "invariant");
445 hr->set_next_dirty_cards_region(NULL);
446 return hr;
447 }
448
449 #ifdef ASSERT
450 // A region is added to the collection set as it is retired
451 // so an address p can point to a region which will be in the
452 // collection set but has not yet been retired. This method
453 // therefore is only accurate during a GC pause after all
454 // regions have been retired. It is used for debugging
455 // to check if an nmethod has references to objects that can
456 // be move during a partial collection. Though it can be
457 // inaccurate, it is sufficient for G1 because the conservative
458 // implementation of is_scavengable() for G1 will indicate that
459 // all nmethods must be scanned during a partial collection.
460 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
461 if (p == NULL) {
462 return false;
463 }
464 return heap_region_containing(p)->in_collection_set();
465 }
466 #endif
467
468 // Returns true if the reference points to an object that
469 // can move in an incremental collection.
470 bool G1CollectedHeap::is_scavengable(const void* p) {
471 HeapRegion* hr = heap_region_containing(p);
472 return !hr->is_humongous();
473 }
474
475 void G1CollectedHeap::check_ct_logs_at_safepoint() {
476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
477 CardTableModRefBS* ct_bs = g1_barrier_set();
478
479 // Count the dirty cards at the start.
480 CountNonCleanMemRegionClosure count1(this);
481 ct_bs->mod_card_iterate(&count1);
482 int orig_count = count1.n();
483
484 // First clear the logged cards.
485 ClearLoggedCardTableEntryClosure clear;
486 dcqs.apply_closure_to_all_completed_buffers(&clear);
487 dcqs.iterate_closure_all_threads(&clear, false);
488 clear.print_histo();
489
490 // Now ensure that there's no dirty cards.
491 CountNonCleanMemRegionClosure count2(this);
492 ct_bs->mod_card_iterate(&count2);
493 if (count2.n() != 0) {
494 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
495 count2.n(), orig_count);
496 }
497 guarantee(count2.n() == 0, "Card table should be clean.");
498
499 RedirtyLoggedCardTableEntryClosure redirty;
500 dcqs.apply_closure_to_all_completed_buffers(&redirty);
501 dcqs.iterate_closure_all_threads(&redirty, false);
502 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
503 clear.num_processed(), orig_count);
504 guarantee(redirty.num_processed() == clear.num_processed(),
505 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
506 redirty.num_processed(), clear.num_processed()));
507
508 CountNonCleanMemRegionClosure count3(this);
509 ct_bs->mod_card_iterate(&count3);
510 if (count3.n() != orig_count) {
511 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
512 orig_count, count3.n());
513 guarantee(count3.n() >= orig_count, "Should have restored them all.");
514 }
515 }
516
517 // Private class members.
518
519 G1CollectedHeap* G1CollectedHeap::_g1h;
520
521 // Private methods.
522
523 HeapRegion*
524 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
525 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
526 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
527 if (!_secondary_free_list.is_empty()) {
528 if (G1ConcRegionFreeingVerbose) {
529 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
530 "secondary_free_list has %u entries",
531 _secondary_free_list.length());
532 }
533 // It looks as if there are free regions available on the
534 // secondary_free_list. Let's move them to the free_list and try
535 // again to allocate from it.
536 append_secondary_free_list();
537
538 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
539 "empty we should have moved at least one entry to the free_list");
540 HeapRegion* res = _hrm.allocate_free_region(is_old);
541 if (G1ConcRegionFreeingVerbose) {
542 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
543 "allocated "HR_FORMAT" from secondary_free_list",
544 HR_FORMAT_PARAMS(res));
545 }
546 return res;
547 }
548
549 // Wait here until we get notified either when (a) there are no
550 // more free regions coming or (b) some regions have been moved on
551 // the secondary_free_list.
552 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
553 }
554
555 if (G1ConcRegionFreeingVerbose) {
556 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
557 "could not allocate from secondary_free_list");
558 }
559 return NULL;
560 }
561
562 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
563 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
564 "the only time we use this to allocate a humongous region is "
565 "when we are allocating a single humongous region");
566
567 HeapRegion* res;
568 if (G1StressConcRegionFreeing) {
569 if (!_secondary_free_list.is_empty()) {
570 if (G1ConcRegionFreeingVerbose) {
571 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
572 "forced to look at the secondary_free_list");
573 }
574 res = new_region_try_secondary_free_list(is_old);
575 if (res != NULL) {
576 return res;
577 }
578 }
579 }
580
581 res = _hrm.allocate_free_region(is_old);
582
583 if (res == NULL) {
584 if (G1ConcRegionFreeingVerbose) {
585 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
586 "res == NULL, trying the secondary_free_list");
587 }
588 res = new_region_try_secondary_free_list(is_old);
589 }
590 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
591 // Currently, only attempts to allocate GC alloc regions set
592 // do_expand to true. So, we should only reach here during a
593 // safepoint. If this assumption changes we might have to
594 // reconsider the use of _expand_heap_after_alloc_failure.
595 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
596
597 ergo_verbose1(ErgoHeapSizing,
598 "attempt heap expansion",
599 ergo_format_reason("region allocation request failed")
600 ergo_format_byte("allocation request"),
601 word_size * HeapWordSize);
602 if (expand(word_size * HeapWordSize)) {
603 // Given that expand() succeeded in expanding the heap, and we
604 // always expand the heap by an amount aligned to the heap
605 // region size, the free list should in theory not be empty.
606 // In either case allocate_free_region() will check for NULL.
607 res = _hrm.allocate_free_region(is_old);
608 } else {
609 _expand_heap_after_alloc_failure = false;
610 }
611 }
612 return res;
613 }
614
615 HeapWord*
616 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
617 uint num_regions,
618 size_t word_size,
619 AllocationContext_t context) {
620 assert(first != G1_NO_HRM_INDEX, "pre-condition");
621 assert(is_humongous(word_size), "word_size should be humongous");
622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
623
624 // Index of last region in the series + 1.
625 uint last = first + num_regions;
626
627 // We need to initialize the region(s) we just discovered. This is
628 // a bit tricky given that it can happen concurrently with
629 // refinement threads refining cards on these regions and
630 // potentially wanting to refine the BOT as they are scanning
631 // those cards (this can happen shortly after a cleanup; see CR
632 // 6991377). So we have to set up the region(s) carefully and in
633 // a specific order.
634
635 // The word size sum of all the regions we will allocate.
636 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
637 assert(word_size <= word_size_sum, "sanity");
638
639 // This will be the "starts humongous" region.
640 HeapRegion* first_hr = region_at(first);
641 // The header of the new object will be placed at the bottom of
642 // the first region.
643 HeapWord* new_obj = first_hr->bottom();
644 // This will be the new end of the first region in the series that
645 // should also match the end of the last region in the series.
646 HeapWord* new_end = new_obj + word_size_sum;
647 // This will be the new top of the first region that will reflect
648 // this allocation.
649 HeapWord* new_top = new_obj + word_size;
650
651 // First, we need to zero the header of the space that we will be
652 // allocating. When we update top further down, some refinement
653 // threads might try to scan the region. By zeroing the header we
654 // ensure that any thread that will try to scan the region will
655 // come across the zero klass word and bail out.
656 //
657 // NOTE: It would not have been correct to have used
658 // CollectedHeap::fill_with_object() and make the space look like
659 // an int array. The thread that is doing the allocation will
660 // later update the object header to a potentially different array
661 // type and, for a very short period of time, the klass and length
662 // fields will be inconsistent. This could cause a refinement
663 // thread to calculate the object size incorrectly.
664 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
665
666 // We will set up the first region as "starts humongous". This
667 // will also update the BOT covering all the regions to reflect
668 // that there is a single object that starts at the bottom of the
669 // first region.
670 first_hr->set_starts_humongous(new_top, new_end);
671 first_hr->set_allocation_context(context);
672 // Then, if there are any, we will set up the "continues
673 // humongous" regions.
674 HeapRegion* hr = NULL;
675 for (uint i = first + 1; i < last; ++i) {
676 hr = region_at(i);
677 hr->set_continues_humongous(first_hr);
678 hr->set_allocation_context(context);
679 }
680 // If we have "continues humongous" regions (hr != NULL), then the
681 // end of the last one should match new_end.
682 assert(hr == NULL || hr->end() == new_end, "sanity");
683
684 // Up to this point no concurrent thread would have been able to
685 // do any scanning on any region in this series. All the top
686 // fields still point to bottom, so the intersection between
687 // [bottom,top] and [card_start,card_end] will be empty. Before we
688 // update the top fields, we'll do a storestore to make sure that
689 // no thread sees the update to top before the zeroing of the
690 // object header and the BOT initialization.
691 OrderAccess::storestore();
692
693 // Now that the BOT and the object header have been initialized,
694 // we can update top of the "starts humongous" region.
695 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
696 "new_top should be in this region");
697 first_hr->set_top(new_top);
698 if (_hr_printer.is_active()) {
699 HeapWord* bottom = first_hr->bottom();
700 HeapWord* end = first_hr->orig_end();
701 if ((first + 1) == last) {
702 // the series has a single humongous region
703 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
704 } else {
705 // the series has more than one humongous regions
706 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
707 }
708 }
709
710 // Now, we will update the top fields of the "continues humongous"
711 // regions. The reason we need to do this is that, otherwise,
712 // these regions would look empty and this will confuse parts of
713 // G1. For example, the code that looks for a consecutive number
714 // of empty regions will consider them empty and try to
715 // re-allocate them. We can extend is_empty() to also include
716 // !is_continues_humongous(), but it is easier to just update the top
717 // fields here. The way we set top for all regions (i.e., top ==
718 // end for all regions but the last one, top == new_top for the
719 // last one) is actually used when we will free up the humongous
720 // region in free_humongous_region().
721 hr = NULL;
722 for (uint i = first + 1; i < last; ++i) {
723 hr = region_at(i);
724 if ((i + 1) == last) {
725 // last continues humongous region
726 assert(hr->bottom() < new_top && new_top <= hr->end(),
727 "new_top should fall on this region");
728 hr->set_top(new_top);
729 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
730 } else {
731 // not last one
732 assert(new_top > hr->end(), "new_top should be above this region");
733 hr->set_top(hr->end());
734 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
735 }
736 }
737 // If we have continues humongous regions (hr != NULL), then the
738 // end of the last one should match new_end and its top should
739 // match new_top.
740 assert(hr == NULL ||
741 (hr->end() == new_end && hr->top() == new_top), "sanity");
742 check_bitmaps("Humongous Region Allocation", first_hr);
743
744 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
745 _allocator->increase_used(first_hr->used());
746 _humongous_set.add(first_hr);
747
748 return new_obj;
749 }
750
751 // If could fit into free regions w/o expansion, try.
752 // Otherwise, if can expand, do so.
753 // Otherwise, if using ex regions might help, try with ex given back.
754 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
755 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
756
757 verify_region_sets_optional();
758
759 uint first = G1_NO_HRM_INDEX;
760 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
761
762 if (obj_regions == 1) {
763 // Only one region to allocate, try to use a fast path by directly allocating
764 // from the free lists. Do not try to expand here, we will potentially do that
765 // later.
766 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
767 if (hr != NULL) {
768 first = hr->hrm_index();
769 }
770 } else {
771 // We can't allocate humongous regions spanning more than one region while
772 // cleanupComplete() is running, since some of the regions we find to be
773 // empty might not yet be added to the free list. It is not straightforward
774 // to know in which list they are on so that we can remove them. We only
775 // need to do this if we need to allocate more than one region to satisfy the
776 // current humongous allocation request. If we are only allocating one region
777 // we use the one-region region allocation code (see above), that already
778 // potentially waits for regions from the secondary free list.
779 wait_while_free_regions_coming();
780 append_secondary_free_list_if_not_empty_with_lock();
781
782 // Policy: Try only empty regions (i.e. already committed first). Maybe we
783 // are lucky enough to find some.
784 first = _hrm.find_contiguous_only_empty(obj_regions);
785 if (first != G1_NO_HRM_INDEX) {
786 _hrm.allocate_free_regions_starting_at(first, obj_regions);
787 }
788 }
789
790 if (first == G1_NO_HRM_INDEX) {
791 // Policy: We could not find enough regions for the humongous object in the
792 // free list. Look through the heap to find a mix of free and uncommitted regions.
793 // If so, try expansion.
794 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
795 if (first != G1_NO_HRM_INDEX) {
796 // We found something. Make sure these regions are committed, i.e. expand
797 // the heap. Alternatively we could do a defragmentation GC.
798 ergo_verbose1(ErgoHeapSizing,
799 "attempt heap expansion",
800 ergo_format_reason("humongous allocation request failed")
801 ergo_format_byte("allocation request"),
802 word_size * HeapWordSize);
803
804 _hrm.expand_at(first, obj_regions);
805 g1_policy()->record_new_heap_size(num_regions());
806
807 #ifdef ASSERT
808 for (uint i = first; i < first + obj_regions; ++i) {
809 HeapRegion* hr = region_at(i);
810 assert(hr->is_free(), "sanity");
811 assert(hr->is_empty(), "sanity");
812 assert(is_on_master_free_list(hr), "sanity");
813 }
814 #endif
815 _hrm.allocate_free_regions_starting_at(first, obj_regions);
816 } else {
817 // Policy: Potentially trigger a defragmentation GC.
818 }
819 }
820
821 HeapWord* result = NULL;
822 if (first != G1_NO_HRM_INDEX) {
823 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
824 word_size, context);
825 assert(result != NULL, "it should always return a valid result");
826
827 // A successful humongous object allocation changes the used space
828 // information of the old generation so we need to recalculate the
829 // sizes and update the jstat counters here.
830 g1mm()->update_sizes();
831 }
832
833 verify_region_sets_optional();
834
835 return result;
836 }
837
838 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
839 assert_heap_not_locked_and_not_at_safepoint();
840 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
841
842 unsigned int dummy_gc_count_before;
843 int dummy_gclocker_retry_count = 0;
844 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
845 }
846
847 HeapWord*
848 G1CollectedHeap::mem_allocate(size_t word_size,
849 bool* gc_overhead_limit_was_exceeded) {
850 assert_heap_not_locked_and_not_at_safepoint();
851
852 // Loop until the allocation is satisfied, or unsatisfied after GC.
853 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
854 unsigned int gc_count_before;
855
856 HeapWord* result = NULL;
857 if (!is_humongous(word_size)) {
858 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
859 } else {
860 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
861 }
862 if (result != NULL) {
863 return result;
864 }
865
866 // Create the garbage collection operation...
867 VM_G1CollectForAllocation op(gc_count_before, word_size);
868 op.set_allocation_context(AllocationContext::current());
869
870 // ...and get the VM thread to execute it.
871 VMThread::execute(&op);
872
873 if (op.prologue_succeeded() && op.pause_succeeded()) {
874 // If the operation was successful we'll return the result even
875 // if it is NULL. If the allocation attempt failed immediately
876 // after a Full GC, it's unlikely we'll be able to allocate now.
877 HeapWord* result = op.result();
878 if (result != NULL && !is_humongous(word_size)) {
879 // Allocations that take place on VM operations do not do any
880 // card dirtying and we have to do it here. We only have to do
881 // this for non-humongous allocations, though.
882 dirty_young_block(result, word_size);
883 }
884 return result;
885 } else {
886 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
887 return NULL;
888 }
889 assert(op.result() == NULL,
890 "the result should be NULL if the VM op did not succeed");
891 }
892
893 // Give a warning if we seem to be looping forever.
894 if ((QueuedAllocationWarningCount > 0) &&
895 (try_count % QueuedAllocationWarningCount == 0)) {
896 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
897 }
898 }
899
900 ShouldNotReachHere();
901 return NULL;
902 }
903
904 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
905 AllocationContext_t context,
906 unsigned int *gc_count_before_ret,
907 int* gclocker_retry_count_ret) {
908 // Make sure you read the note in attempt_allocation_humongous().
909
910 assert_heap_not_locked_and_not_at_safepoint();
911 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
912 "be called for humongous allocation requests");
913
914 // We should only get here after the first-level allocation attempt
915 // (attempt_allocation()) failed to allocate.
916
917 // We will loop until a) we manage to successfully perform the
918 // allocation or b) we successfully schedule a collection which
919 // fails to perform the allocation. b) is the only case when we'll
920 // return NULL.
921 HeapWord* result = NULL;
922 for (int try_count = 1; /* we'll return */; try_count += 1) {
923 bool should_try_gc;
924 unsigned int gc_count_before;
925
926 {
927 MutexLockerEx x(Heap_lock);
928 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
929 false /* bot_updates */);
930 if (result != NULL) {
931 return result;
932 }
933
934 // If we reach here, attempt_allocation_locked() above failed to
935 // allocate a new region. So the mutator alloc region should be NULL.
936 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
937
938 if (GC_locker::is_active_and_needs_gc()) {
939 if (g1_policy()->can_expand_young_list()) {
940 // No need for an ergo verbose message here,
941 // can_expand_young_list() does this when it returns true.
942 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
943 false /* bot_updates */);
944 if (result != NULL) {
945 return result;
946 }
947 }
948 should_try_gc = false;
949 } else {
950 // The GCLocker may not be active but the GCLocker initiated
951 // GC may not yet have been performed (GCLocker::needs_gc()
952 // returns true). In this case we do not try this GC and
953 // wait until the GCLocker initiated GC is performed, and
954 // then retry the allocation.
955 if (GC_locker::needs_gc()) {
956 should_try_gc = false;
957 } else {
958 // Read the GC count while still holding the Heap_lock.
959 gc_count_before = total_collections();
960 should_try_gc = true;
961 }
962 }
963 }
964
965 if (should_try_gc) {
966 bool succeeded;
967 result = do_collection_pause(word_size, gc_count_before, &succeeded,
968 GCCause::_g1_inc_collection_pause);
969 if (result != NULL) {
970 assert(succeeded, "only way to get back a non-NULL result");
971 return result;
972 }
973
974 if (succeeded) {
975 // If we get here we successfully scheduled a collection which
976 // failed to allocate. No point in trying to allocate
977 // further. We'll just return NULL.
978 MutexLockerEx x(Heap_lock);
979 *gc_count_before_ret = total_collections();
980 return NULL;
981 }
982 } else {
983 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
984 MutexLockerEx x(Heap_lock);
985 *gc_count_before_ret = total_collections();
986 return NULL;
987 }
988 // The GCLocker is either active or the GCLocker initiated
989 // GC has not yet been performed. Stall until it is and
990 // then retry the allocation.
991 GC_locker::stall_until_clear();
992 (*gclocker_retry_count_ret) += 1;
993 }
994
995 // We can reach here if we were unsuccessful in scheduling a
996 // collection (because another thread beat us to it) or if we were
997 // stalled due to the GC locker. In either can we should retry the
998 // allocation attempt in case another thread successfully
999 // performed a collection and reclaimed enough space. We do the
1000 // first attempt (without holding the Heap_lock) here and the
1001 // follow-on attempt will be at the start of the next loop
1002 // iteration (after taking the Heap_lock).
1003 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
1004 false /* bot_updates */);
1005 if (result != NULL) {
1006 return result;
1007 }
1008
1009 // Give a warning if we seem to be looping forever.
1010 if ((QueuedAllocationWarningCount > 0) &&
1011 (try_count % QueuedAllocationWarningCount == 0)) {
1012 warning("G1CollectedHeap::attempt_allocation_slow() "
1013 "retries %d times", try_count);
1014 }
1015 }
1016
1017 ShouldNotReachHere();
1018 return NULL;
1019 }
1020
1021 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1022 unsigned int * gc_count_before_ret,
1023 int* gclocker_retry_count_ret) {
1024 // The structure of this method has a lot of similarities to
1025 // attempt_allocation_slow(). The reason these two were not merged
1026 // into a single one is that such a method would require several "if
1027 // allocation is not humongous do this, otherwise do that"
1028 // conditional paths which would obscure its flow. In fact, an early
1029 // version of this code did use a unified method which was harder to
1030 // follow and, as a result, it had subtle bugs that were hard to
1031 // track down. So keeping these two methods separate allows each to
1032 // be more readable. It will be good to keep these two in sync as
1033 // much as possible.
1034
1035 assert_heap_not_locked_and_not_at_safepoint();
1036 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1037 "should only be called for humongous allocations");
1038
1039 // Humongous objects can exhaust the heap quickly, so we should check if we
1040 // need to start a marking cycle at each humongous object allocation. We do
1041 // the check before we do the actual allocation. The reason for doing it
1042 // before the allocation is that we avoid having to keep track of the newly
1043 // allocated memory while we do a GC.
1044 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1045 word_size)) {
1046 collect(GCCause::_g1_humongous_allocation);
1047 }
1048
1049 // We will loop until a) we manage to successfully perform the
1050 // allocation or b) we successfully schedule a collection which
1051 // fails to perform the allocation. b) is the only case when we'll
1052 // return NULL.
1053 HeapWord* result = NULL;
1054 for (int try_count = 1; /* we'll return */; try_count += 1) {
1055 bool should_try_gc;
1056 unsigned int gc_count_before;
1057
1058 {
1059 MutexLockerEx x(Heap_lock);
1060
1061 // Given that humongous objects are not allocated in young
1062 // regions, we'll first try to do the allocation without doing a
1063 // collection hoping that there's enough space in the heap.
1064 result = humongous_obj_allocate(word_size, AllocationContext::current());
1065 if (result != NULL) {
1066 return result;
1067 }
1068
1069 if (GC_locker::is_active_and_needs_gc()) {
1070 should_try_gc = false;
1071 } else {
1072 // The GCLocker may not be active but the GCLocker initiated
1073 // GC may not yet have been performed (GCLocker::needs_gc()
1074 // returns true). In this case we do not try this GC and
1075 // wait until the GCLocker initiated GC is performed, and
1076 // then retry the allocation.
1077 if (GC_locker::needs_gc()) {
1078 should_try_gc = false;
1079 } else {
1080 // Read the GC count while still holding the Heap_lock.
1081 gc_count_before = total_collections();
1082 should_try_gc = true;
1083 }
1084 }
1085 }
1086
1087 if (should_try_gc) {
1088 // If we failed to allocate the humongous object, we should try to
1089 // do a collection pause (if we're allowed) in case it reclaims
1090 // enough space for the allocation to succeed after the pause.
1091
1092 bool succeeded;
1093 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1094 GCCause::_g1_humongous_allocation);
1095 if (result != NULL) {
1096 assert(succeeded, "only way to get back a non-NULL result");
1097 return result;
1098 }
1099
1100 if (succeeded) {
1101 // If we get here we successfully scheduled a collection which
1102 // failed to allocate. No point in trying to allocate
1103 // further. We'll just return NULL.
1104 MutexLockerEx x(Heap_lock);
1105 *gc_count_before_ret = total_collections();
1106 return NULL;
1107 }
1108 } else {
1109 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1110 MutexLockerEx x(Heap_lock);
1111 *gc_count_before_ret = total_collections();
1112 return NULL;
1113 }
1114 // The GCLocker is either active or the GCLocker initiated
1115 // GC has not yet been performed. Stall until it is and
1116 // then retry the allocation.
1117 GC_locker::stall_until_clear();
1118 (*gclocker_retry_count_ret) += 1;
1119 }
1120
1121 // We can reach here if we were unsuccessful in scheduling a
1122 // collection (because another thread beat us to it) or if we were
1123 // stalled due to the GC locker. In either can we should retry the
1124 // allocation attempt in case another thread successfully
1125 // performed a collection and reclaimed enough space. Give a
1126 // warning if we seem to be looping forever.
1127
1128 if ((QueuedAllocationWarningCount > 0) &&
1129 (try_count % QueuedAllocationWarningCount == 0)) {
1130 warning("G1CollectedHeap::attempt_allocation_humongous() "
1131 "retries %d times", try_count);
1132 }
1133 }
1134
1135 ShouldNotReachHere();
1136 return NULL;
1137 }
1138
1139 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1140 AllocationContext_t context,
1141 bool expect_null_mutator_alloc_region) {
1142 assert_at_safepoint(true /* should_be_vm_thread */);
1143 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1144 !expect_null_mutator_alloc_region,
1145 "the current alloc region was unexpectedly found to be non-NULL");
1146
1147 if (!is_humongous(word_size)) {
1148 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1149 false /* bot_updates */);
1150 } else {
1151 HeapWord* result = humongous_obj_allocate(word_size, context);
1152 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1153 g1_policy()->set_initiate_conc_mark_if_possible();
1154 }
1155 return result;
1156 }
1157
1158 ShouldNotReachHere();
1159 }
1160
1161 class PostMCRemSetClearClosure: public HeapRegionClosure {
1162 G1CollectedHeap* _g1h;
1163 ModRefBarrierSet* _mr_bs;
1164 public:
1165 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1166 _g1h(g1h), _mr_bs(mr_bs) {}
1167
1168 bool doHeapRegion(HeapRegion* r) {
1169 HeapRegionRemSet* hrrs = r->rem_set();
1170
1171 if (r->is_continues_humongous()) {
1172 // We'll assert that the strong code root list and RSet is empty
1173 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1174 assert(hrrs->occupied() == 0, "RSet should be empty");
1175 return false;
1176 }
1177
1178 _g1h->reset_gc_time_stamps(r);
1179 hrrs->clear();
1180 // You might think here that we could clear just the cards
1181 // corresponding to the used region. But no: if we leave a dirty card
1182 // in a region we might allocate into, then it would prevent that card
1183 // from being enqueued, and cause it to be missed.
1184 // Re: the performance cost: we shouldn't be doing full GC anyway!
1185 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1186
1187 return false;
1188 }
1189 };
1190
1191 void G1CollectedHeap::clear_rsets_post_compaction() {
1192 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1193 heap_region_iterate(&rs_clear);
1194 }
1195
1196 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1197 G1CollectedHeap* _g1h;
1198 UpdateRSOopClosure _cl;
1199 int _worker_i;
1200 public:
1201 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1202 _cl(g1->g1_rem_set(), worker_i),
1203 _worker_i(worker_i),
1204 _g1h(g1)
1205 { }
1206
1207 bool doHeapRegion(HeapRegion* r) {
1208 if (!r->is_continues_humongous()) {
1209 _cl.set_from(r);
1210 r->oop_iterate(&_cl);
1211 }
1212 return false;
1213 }
1214 };
1215
1216 class ParRebuildRSTask: public AbstractGangTask {
1217 G1CollectedHeap* _g1;
1218 HeapRegionClaimer _hrclaimer;
1219
1220 public:
1221 ParRebuildRSTask(G1CollectedHeap* g1) :
1222 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1223
1224 void work(uint worker_id) {
1225 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1226 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1227 }
1228 };
1229
1230 class PostCompactionPrinterClosure: public HeapRegionClosure {
1231 private:
1232 G1HRPrinter* _hr_printer;
1233 public:
1234 bool doHeapRegion(HeapRegion* hr) {
1235 assert(!hr->is_young(), "not expecting to find young regions");
1236 if (hr->is_free()) {
1237 // We only generate output for non-empty regions.
1238 } else if (hr->is_starts_humongous()) {
1239 if (hr->region_num() == 1) {
1240 // single humongous region
1241 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1242 } else {
1243 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1244 }
1245 } else if (hr->is_continues_humongous()) {
1246 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1247 } else if (hr->is_old()) {
1248 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1249 } else {
1250 ShouldNotReachHere();
1251 }
1252 return false;
1253 }
1254
1255 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1256 : _hr_printer(hr_printer) { }
1257 };
1258
1259 void G1CollectedHeap::print_hrm_post_compaction() {
1260 PostCompactionPrinterClosure cl(hr_printer());
1261 heap_region_iterate(&cl);
1262 }
1263
1264 bool G1CollectedHeap::do_collection(bool explicit_gc,
1265 bool clear_all_soft_refs,
1266 size_t word_size) {
1267 assert_at_safepoint(true /* should_be_vm_thread */);
1268
1269 if (GC_locker::check_active_before_gc()) {
1270 return false;
1271 }
1272
1273 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1274 gc_timer->register_gc_start();
1275
1276 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1277 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1278
1279 SvcGCMarker sgcm(SvcGCMarker::FULL);
1280 ResourceMark rm;
1281
1282 print_heap_before_gc();
1283 trace_heap_before_gc(gc_tracer);
1284
1285 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1286
1287 verify_region_sets_optional();
1288
1289 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1290 collector_policy()->should_clear_all_soft_refs();
1291
1292 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1293
1294 {
1295 IsGCActiveMark x;
1296
1297 // Timing
1298 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1299 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1300 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1301
1302 {
1303 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1304 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1305 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1306
1307 double start = os::elapsedTime();
1308 g1_policy()->record_full_collection_start();
1309
1310 // Note: When we have a more flexible GC logging framework that
1311 // allows us to add optional attributes to a GC log record we
1312 // could consider timing and reporting how long we wait in the
1313 // following two methods.
1314 wait_while_free_regions_coming();
1315 // If we start the compaction before the CM threads finish
1316 // scanning the root regions we might trip them over as we'll
1317 // be moving objects / updating references. So let's wait until
1318 // they are done. By telling them to abort, they should complete
1319 // early.
1320 _cm->root_regions()->abort();
1321 _cm->root_regions()->wait_until_scan_finished();
1322 append_secondary_free_list_if_not_empty_with_lock();
1323
1324 gc_prologue(true);
1325 increment_total_collections(true /* full gc */);
1326 increment_old_marking_cycles_started();
1327
1328 assert(used() == recalculate_used(), "Should be equal");
1329
1330 verify_before_gc();
1331
1332 check_bitmaps("Full GC Start");
1333 pre_full_gc_dump(gc_timer);
1334
1335 COMPILER2_PRESENT(DerivedPointerTable::clear());
1336
1337 // Disable discovery and empty the discovered lists
1338 // for the CM ref processor.
1339 ref_processor_cm()->disable_discovery();
1340 ref_processor_cm()->abandon_partial_discovery();
1341 ref_processor_cm()->verify_no_references_recorded();
1342
1343 // Abandon current iterations of concurrent marking and concurrent
1344 // refinement, if any are in progress. We have to do this before
1345 // wait_until_scan_finished() below.
1346 concurrent_mark()->abort();
1347
1348 // Make sure we'll choose a new allocation region afterwards.
1349 _allocator->release_mutator_alloc_region();
1350 _allocator->abandon_gc_alloc_regions();
1351 g1_rem_set()->cleanupHRRS();
1352
1353 // We should call this after we retire any currently active alloc
1354 // regions so that all the ALLOC / RETIRE events are generated
1355 // before the start GC event.
1356 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1357
1358 // We may have added regions to the current incremental collection
1359 // set between the last GC or pause and now. We need to clear the
1360 // incremental collection set and then start rebuilding it afresh
1361 // after this full GC.
1362 abandon_collection_set(g1_policy()->inc_cset_head());
1363 g1_policy()->clear_incremental_cset();
1364 g1_policy()->stop_incremental_cset_building();
1365
1366 tear_down_region_sets(false /* free_list_only */);
1367 g1_policy()->set_gcs_are_young(true);
1368
1369 // See the comments in g1CollectedHeap.hpp and
1370 // G1CollectedHeap::ref_processing_init() about
1371 // how reference processing currently works in G1.
1372
1373 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1374 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1375
1376 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1377 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1378
1379 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1380 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1381
1382 // Do collection work
1383 {
1384 HandleMark hm; // Discard invalid handles created during gc
1385 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1386 }
1387
1388 assert(num_free_regions() == 0, "we should not have added any free regions");
1389 rebuild_region_sets(false /* free_list_only */);
1390
1391 // Enqueue any discovered reference objects that have
1392 // not been removed from the discovered lists.
1393 ref_processor_stw()->enqueue_discovered_references();
1394
1395 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1396
1397 MemoryService::track_memory_usage();
1398
1399 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1400 ref_processor_stw()->verify_no_references_recorded();
1401
1402 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1403 ClassLoaderDataGraph::purge();
1404 MetaspaceAux::verify_metrics();
1405
1406 // Note: since we've just done a full GC, concurrent
1407 // marking is no longer active. Therefore we need not
1408 // re-enable reference discovery for the CM ref processor.
1409 // That will be done at the start of the next marking cycle.
1410 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1411 ref_processor_cm()->verify_no_references_recorded();
1412
1413 reset_gc_time_stamp();
1414 // Since everything potentially moved, we will clear all remembered
1415 // sets, and clear all cards. Later we will rebuild remembered
1416 // sets. We will also reset the GC time stamps of the regions.
1417 clear_rsets_post_compaction();
1418 check_gc_time_stamps();
1419
1420 // Resize the heap if necessary.
1421 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1422
1423 if (_hr_printer.is_active()) {
1424 // We should do this after we potentially resize the heap so
1425 // that all the COMMIT / UNCOMMIT events are generated before
1426 // the end GC event.
1427
1428 print_hrm_post_compaction();
1429 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1430 }
1431
1432 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1433 if (hot_card_cache->use_cache()) {
1434 hot_card_cache->reset_card_counts();
1435 hot_card_cache->reset_hot_cache();
1436 }
1437
1438 // Rebuild remembered sets of all regions.
1439 if (G1CollectedHeap::use_parallel_gc_threads()) {
1440 uint n_workers =
1441 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1442 workers()->active_workers(),
1443 Threads::number_of_non_daemon_threads());
1444 assert(UseDynamicNumberOfGCThreads ||
1445 n_workers == workers()->total_workers(),
1446 "If not dynamic should be using all the workers");
1447 workers()->set_active_workers(n_workers);
1448 // Set parallel threads in the heap (_n_par_threads) only
1449 // before a parallel phase and always reset it to 0 after
1450 // the phase so that the number of parallel threads does
1451 // no get carried forward to a serial phase where there
1452 // may be code that is "possibly_parallel".
1453 set_par_threads(n_workers);
1454
1455 ParRebuildRSTask rebuild_rs_task(this);
1456 assert(UseDynamicNumberOfGCThreads ||
1457 workers()->active_workers() == workers()->total_workers(),
1458 "Unless dynamic should use total workers");
1459 // Use the most recent number of active workers
1460 assert(workers()->active_workers() > 0,
1461 "Active workers not properly set");
1462 set_par_threads(workers()->active_workers());
1463 workers()->run_task(&rebuild_rs_task);
1464 set_par_threads(0);
1465 } else {
1466 RebuildRSOutOfRegionClosure rebuild_rs(this);
1467 heap_region_iterate(&rebuild_rs);
1468 }
1469
1470 // Rebuild the strong code root lists for each region
1471 rebuild_strong_code_roots();
1472
1473 if (true) { // FIXME
1474 MetaspaceGC::compute_new_size();
1475 }
1476
1477 #ifdef TRACESPINNING
1478 ParallelTaskTerminator::print_termination_counts();
1479 #endif
1480
1481 // Discard all rset updates
1482 JavaThread::dirty_card_queue_set().abandon_logs();
1483 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1484
1485 _young_list->reset_sampled_info();
1486 // At this point there should be no regions in the
1487 // entire heap tagged as young.
1488 assert(check_young_list_empty(true /* check_heap */),
1489 "young list should be empty at this point");
1490
1491 // Update the number of full collections that have been completed.
1492 increment_old_marking_cycles_completed(false /* concurrent */);
1493
1494 _hrm.verify_optional();
1495 verify_region_sets_optional();
1496
1497 verify_after_gc();
1498
1499 // Clear the previous marking bitmap, if needed for bitmap verification.
1500 // Note we cannot do this when we clear the next marking bitmap in
1501 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1502 // objects marked during a full GC against the previous bitmap.
1503 // But we need to clear it before calling check_bitmaps below since
1504 // the full GC has compacted objects and updated TAMS but not updated
1505 // the prev bitmap.
1506 if (G1VerifyBitmaps) {
1507 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1508 }
1509 check_bitmaps("Full GC End");
1510
1511 // Start a new incremental collection set for the next pause
1512 assert(g1_policy()->collection_set() == NULL, "must be");
1513 g1_policy()->start_incremental_cset_building();
1514
1515 clear_cset_fast_test();
1516
1517 _allocator->init_mutator_alloc_region();
1518
1519 double end = os::elapsedTime();
1520 g1_policy()->record_full_collection_end();
1521
1522 if (G1Log::fine()) {
1523 g1_policy()->print_heap_transition();
1524 }
1525
1526 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1527 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1528 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1529 // before any GC notifications are raised.
1530 g1mm()->update_sizes();
1531
1532 gc_epilogue(true);
1533 }
1534
1535 if (G1Log::finer()) {
1536 g1_policy()->print_detailed_heap_transition(true /* full */);
1537 }
1538
1539 print_heap_after_gc();
1540 trace_heap_after_gc(gc_tracer);
1541
1542 post_full_gc_dump(gc_timer);
1543
1544 gc_timer->register_gc_end();
1545 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1546 }
1547
1548 return true;
1549 }
1550
1551 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1552 // do_collection() will return whether it succeeded in performing
1553 // the GC. Currently, there is no facility on the
1554 // do_full_collection() API to notify the caller than the collection
1555 // did not succeed (e.g., because it was locked out by the GC
1556 // locker). So, right now, we'll ignore the return value.
1557 bool dummy = do_collection(true, /* explicit_gc */
1558 clear_all_soft_refs,
1559 0 /* word_size */);
1560 }
1561
1562 // This code is mostly copied from TenuredGeneration.
1563 void
1564 G1CollectedHeap::
1565 resize_if_necessary_after_full_collection(size_t word_size) {
1566 // Include the current allocation, if any, and bytes that will be
1567 // pre-allocated to support collections, as "used".
1568 const size_t used_after_gc = used();
1569 const size_t capacity_after_gc = capacity();
1570 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1571
1572 // This is enforced in arguments.cpp.
1573 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1574 "otherwise the code below doesn't make sense");
1575
1576 // We don't have floating point command-line arguments
1577 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1578 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1579 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1580 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1581
1582 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1583 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1584
1585 // We have to be careful here as these two calculations can overflow
1586 // 32-bit size_t's.
1587 double used_after_gc_d = (double) used_after_gc;
1588 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1589 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1590
1591 // Let's make sure that they are both under the max heap size, which
1592 // by default will make them fit into a size_t.
1593 double desired_capacity_upper_bound = (double) max_heap_size;
1594 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1595 desired_capacity_upper_bound);
1596 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1597 desired_capacity_upper_bound);
1598
1599 // We can now safely turn them into size_t's.
1600 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1601 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1602
1603 // This assert only makes sense here, before we adjust them
1604 // with respect to the min and max heap size.
1605 assert(minimum_desired_capacity <= maximum_desired_capacity,
1606 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1607 "maximum_desired_capacity = "SIZE_FORMAT,
1608 minimum_desired_capacity, maximum_desired_capacity));
1609
1610 // Should not be greater than the heap max size. No need to adjust
1611 // it with respect to the heap min size as it's a lower bound (i.e.,
1612 // we'll try to make the capacity larger than it, not smaller).
1613 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1614 // Should not be less than the heap min size. No need to adjust it
1615 // with respect to the heap max size as it's an upper bound (i.e.,
1616 // we'll try to make the capacity smaller than it, not greater).
1617 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1618
1619 if (capacity_after_gc < minimum_desired_capacity) {
1620 // Don't expand unless it's significant
1621 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1622 ergo_verbose4(ErgoHeapSizing,
1623 "attempt heap expansion",
1624 ergo_format_reason("capacity lower than "
1625 "min desired capacity after Full GC")
1626 ergo_format_byte("capacity")
1627 ergo_format_byte("occupancy")
1628 ergo_format_byte_perc("min desired capacity"),
1629 capacity_after_gc, used_after_gc,
1630 minimum_desired_capacity, (double) MinHeapFreeRatio);
1631 expand(expand_bytes);
1632
1633 // No expansion, now see if we want to shrink
1634 } else if (capacity_after_gc > maximum_desired_capacity) {
1635 // Capacity too large, compute shrinking size
1636 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1637 ergo_verbose4(ErgoHeapSizing,
1638 "attempt heap shrinking",
1639 ergo_format_reason("capacity higher than "
1640 "max desired capacity after Full GC")
1641 ergo_format_byte("capacity")
1642 ergo_format_byte("occupancy")
1643 ergo_format_byte_perc("max desired capacity"),
1644 capacity_after_gc, used_after_gc,
1645 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1646 shrink(shrink_bytes);
1647 }
1648 }
1649
1650
1651 HeapWord*
1652 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1653 AllocationContext_t context,
1654 bool* succeeded) {
1655 assert_at_safepoint(true /* should_be_vm_thread */);
1656
1657 *succeeded = true;
1658 // Let's attempt the allocation first.
1659 HeapWord* result =
1660 attempt_allocation_at_safepoint(word_size,
1661 context,
1662 false /* expect_null_mutator_alloc_region */);
1663 if (result != NULL) {
1664 assert(*succeeded, "sanity");
1665 return result;
1666 }
1667
1668 // In a G1 heap, we're supposed to keep allocation from failing by
1669 // incremental pauses. Therefore, at least for now, we'll favor
1670 // expansion over collection. (This might change in the future if we can
1671 // do something smarter than full collection to satisfy a failed alloc.)
1672 result = expand_and_allocate(word_size, context);
1673 if (result != NULL) {
1674 assert(*succeeded, "sanity");
1675 return result;
1676 }
1677
1678 // Expansion didn't work, we'll try to do a Full GC.
1679 bool gc_succeeded = do_collection(false, /* explicit_gc */
1680 false, /* clear_all_soft_refs */
1681 word_size);
1682 if (!gc_succeeded) {
1683 *succeeded = false;
1684 return NULL;
1685 }
1686
1687 // Retry the allocation
1688 result = attempt_allocation_at_safepoint(word_size,
1689 context,
1690 true /* expect_null_mutator_alloc_region */);
1691 if (result != NULL) {
1692 assert(*succeeded, "sanity");
1693 return result;
1694 }
1695
1696 // Then, try a Full GC that will collect all soft references.
1697 gc_succeeded = do_collection(false, /* explicit_gc */
1698 true, /* clear_all_soft_refs */
1699 word_size);
1700 if (!gc_succeeded) {
1701 *succeeded = false;
1702 return NULL;
1703 }
1704
1705 // Retry the allocation once more
1706 result = attempt_allocation_at_safepoint(word_size,
1707 context,
1708 true /* expect_null_mutator_alloc_region */);
1709 if (result != NULL) {
1710 assert(*succeeded, "sanity");
1711 return result;
1712 }
1713
1714 assert(!collector_policy()->should_clear_all_soft_refs(),
1715 "Flag should have been handled and cleared prior to this point");
1716
1717 // What else? We might try synchronous finalization later. If the total
1718 // space available is large enough for the allocation, then a more
1719 // complete compaction phase than we've tried so far might be
1720 // appropriate.
1721 assert(*succeeded, "sanity");
1722 return NULL;
1723 }
1724
1725 // Attempting to expand the heap sufficiently
1726 // to support an allocation of the given "word_size". If
1727 // successful, perform the allocation and return the address of the
1728 // allocated block, or else "NULL".
1729
1730 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1731 assert_at_safepoint(true /* should_be_vm_thread */);
1732
1733 verify_region_sets_optional();
1734
1735 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1736 ergo_verbose1(ErgoHeapSizing,
1737 "attempt heap expansion",
1738 ergo_format_reason("allocation request failed")
1739 ergo_format_byte("allocation request"),
1740 word_size * HeapWordSize);
1741 if (expand(expand_bytes)) {
1742 _hrm.verify_optional();
1743 verify_region_sets_optional();
1744 return attempt_allocation_at_safepoint(word_size,
1745 context,
1746 false /* expect_null_mutator_alloc_region */);
1747 }
1748 return NULL;
1749 }
1750
1751 bool G1CollectedHeap::expand(size_t expand_bytes) {
1752 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1753 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1754 HeapRegion::GrainBytes);
1755 ergo_verbose2(ErgoHeapSizing,
1756 "expand the heap",
1757 ergo_format_byte("requested expansion amount")
1758 ergo_format_byte("attempted expansion amount"),
1759 expand_bytes, aligned_expand_bytes);
1760
1761 if (is_maximal_no_gc()) {
1762 ergo_verbose0(ErgoHeapSizing,
1763 "did not expand the heap",
1764 ergo_format_reason("heap already fully expanded"));
1765 return false;
1766 }
1767
1768 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1769 assert(regions_to_expand > 0, "Must expand by at least one region");
1770
1771 uint expanded_by = _hrm.expand_by(regions_to_expand);
1772
1773 if (expanded_by > 0) {
1774 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1775 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1776 g1_policy()->record_new_heap_size(num_regions());
1777 } else {
1778 ergo_verbose0(ErgoHeapSizing,
1779 "did not expand the heap",
1780 ergo_format_reason("heap expansion operation failed"));
1781 // The expansion of the virtual storage space was unsuccessful.
1782 // Let's see if it was because we ran out of swap.
1783 if (G1ExitOnExpansionFailure &&
1784 _hrm.available() >= regions_to_expand) {
1785 // We had head room...
1786 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1787 }
1788 }
1789 return regions_to_expand > 0;
1790 }
1791
1792 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1793 size_t aligned_shrink_bytes =
1794 ReservedSpace::page_align_size_down(shrink_bytes);
1795 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1796 HeapRegion::GrainBytes);
1797 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1798
1799 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1800 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1801
1802 ergo_verbose3(ErgoHeapSizing,
1803 "shrink the heap",
1804 ergo_format_byte("requested shrinking amount")
1805 ergo_format_byte("aligned shrinking amount")
1806 ergo_format_byte("attempted shrinking amount"),
1807 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1808 if (num_regions_removed > 0) {
1809 g1_policy()->record_new_heap_size(num_regions());
1810 } else {
1811 ergo_verbose0(ErgoHeapSizing,
1812 "did not shrink the heap",
1813 ergo_format_reason("heap shrinking operation failed"));
1814 }
1815 }
1816
1817 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1818 verify_region_sets_optional();
1819
1820 // We should only reach here at the end of a Full GC which means we
1821 // should not not be holding to any GC alloc regions. The method
1822 // below will make sure of that and do any remaining clean up.
1823 _allocator->abandon_gc_alloc_regions();
1824
1825 // Instead of tearing down / rebuilding the free lists here, we
1826 // could instead use the remove_all_pending() method on free_list to
1827 // remove only the ones that we need to remove.
1828 tear_down_region_sets(true /* free_list_only */);
1829 shrink_helper(shrink_bytes);
1830 rebuild_region_sets(true /* free_list_only */);
1831
1832 _hrm.verify_optional();
1833 verify_region_sets_optional();
1834 }
1835
1836 // Public methods.
1837
1838 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1839 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1840 #endif // _MSC_VER
1841
1842
1843 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1844 SharedHeap(policy_),
1845 _g1_policy(policy_),
1846 _dirty_card_queue_set(false),
1847 _into_cset_dirty_card_queue_set(false),
1848 _is_alive_closure_cm(this),
1849 _is_alive_closure_stw(this),
1850 _ref_processor_cm(NULL),
1851 _ref_processor_stw(NULL),
1852 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1853 _bot_shared(NULL),
1854 _evac_failure_scan_stack(NULL),
1855 _mark_in_progress(false),
1856 _cg1r(NULL),
1857 _g1mm(NULL),
1858 _refine_cte_cl(NULL),
1859 _full_collection(false),
1860 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1861 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1862 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1863 _humongous_is_live(),
1864 _has_humongous_reclaim_candidates(false),
1865 _free_regions_coming(false),
1866 _young_list(new YoungList(this)),
1867 _gc_time_stamp(0),
1868 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1869 _old_plab_stats(OldPLABSize, PLABWeight),
1870 _expand_heap_after_alloc_failure(true),
1871 _surviving_young_words(NULL),
1872 _old_marking_cycles_started(0),
1873 _old_marking_cycles_completed(0),
1874 _concurrent_cycle_started(false),
1875 _heap_summary_sent(false),
1876 _in_cset_fast_test(),
1877 _dirty_cards_region_list(NULL),
1878 _worker_cset_start_region(NULL),
1879 _worker_cset_start_region_time_stamp(NULL),
1880 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1881 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1882 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1883 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1884
1885 _g1h = this;
1886 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1887 vm_exit_during_initialization("Failed necessary allocation.");
1888 }
1889
1890 _allocator = G1Allocator::create_allocator(_g1h);
1891 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1892
1893 int n_queues = MAX2((int)ParallelGCThreads, 1);
1894 _task_queues = new RefToScanQueueSet(n_queues);
1895
1896 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1897 assert(n_rem_sets > 0, "Invariant.");
1898
1899 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1900 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1901 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1902
1903 for (int i = 0; i < n_queues; i++) {
1904 RefToScanQueue* q = new RefToScanQueue();
1905 q->initialize();
1906 _task_queues->register_queue(i, q);
1907 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1908 }
1909 clear_cset_start_regions();
1910
1911 // Initialize the G1EvacuationFailureALot counters and flags.
1912 NOT_PRODUCT(reset_evacuation_should_fail();)
1913
1914 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1915 }
1916
1917 jint G1CollectedHeap::initialize() {
1918 CollectedHeap::pre_initialize();
1919 os::enable_vtime();
1920
1921 G1Log::init();
1922
1923 // Necessary to satisfy locking discipline assertions.
1924
1925 MutexLocker x(Heap_lock);
1926
1927 // We have to initialize the printer before committing the heap, as
1928 // it will be used then.
1929 _hr_printer.set_active(G1PrintHeapRegions);
1930
1931 // While there are no constraints in the GC code that HeapWordSize
1932 // be any particular value, there are multiple other areas in the
1933 // system which believe this to be true (e.g. oop->object_size in some
1934 // cases incorrectly returns the size in wordSize units rather than
1935 // HeapWordSize).
1936 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1937
1938 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1939 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1940 size_t heap_alignment = collector_policy()->heap_alignment();
1941
1942 // Ensure that the sizes are properly aligned.
1943 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1944 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1945 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1946
1947 _refine_cte_cl = new RefineCardTableEntryClosure();
1948
1949 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1950
1951 // Reserve the maximum.
1952
1953 // When compressed oops are enabled, the preferred heap base
1954 // is calculated by subtracting the requested size from the
1955 // 32Gb boundary and using the result as the base address for
1956 // heap reservation. If the requested size is not aligned to
1957 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1958 // into the ReservedHeapSpace constructor) then the actual
1959 // base of the reserved heap may end up differing from the
1960 // address that was requested (i.e. the preferred heap base).
1961 // If this happens then we could end up using a non-optimal
1962 // compressed oops mode.
1963
1964 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1965 heap_alignment);
1966
1967 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1968
1969 // Create the gen rem set (and barrier set) for the entire reserved region.
1970 _rem_set = collector_policy()->create_rem_set(reserved_region(), 2);
1971 set_barrier_set(rem_set()->bs());
1972 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1973 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1974 return JNI_ENOMEM;
1975 }
1976
1977 // Also create a G1 rem set.
1978 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1979
1980 // Carve out the G1 part of the heap.
1981
1982 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1983 G1RegionToSpaceMapper* heap_storage =
1984 G1RegionToSpaceMapper::create_mapper(g1_rs,
1985 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1986 HeapRegion::GrainBytes,
1987 1,
1988 mtJavaHeap);
1989 heap_storage->set_mapping_changed_listener(&_listener);
1990
1991 // Reserve space for the block offset table. We do not support automatic uncommit
1992 // for the card table at this time. BOT only.
1993 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1994 G1RegionToSpaceMapper* bot_storage =
1995 G1RegionToSpaceMapper::create_mapper(bot_rs,
1996 os::vm_page_size(),
1997 HeapRegion::GrainBytes,
1998 G1BlockOffsetSharedArray::N_bytes,
1999 mtGC);
2000
2001 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2002 G1RegionToSpaceMapper* cardtable_storage =
2003 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
2004 os::vm_page_size(),
2005 HeapRegion::GrainBytes,
2006 G1BlockOffsetSharedArray::N_bytes,
2007 mtGC);
2008
2009 // Reserve space for the card counts table.
2010 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
2011 G1RegionToSpaceMapper* card_counts_storage =
2012 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
2013 os::vm_page_size(),
2014 HeapRegion::GrainBytes,
2015 G1BlockOffsetSharedArray::N_bytes,
2016 mtGC);
2017
2018 // Reserve space for prev and next bitmap.
2019 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2020
2021 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2022 G1RegionToSpaceMapper* prev_bitmap_storage =
2023 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
2024 os::vm_page_size(),
2025 HeapRegion::GrainBytes,
2026 CMBitMap::mark_distance(),
2027 mtGC);
2028
2029 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2030 G1RegionToSpaceMapper* next_bitmap_storage =
2031 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
2032 os::vm_page_size(),
2033 HeapRegion::GrainBytes,
2034 CMBitMap::mark_distance(),
2035 mtGC);
2036
2037 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2038 g1_barrier_set()->initialize(cardtable_storage);
2039 // Do later initialization work for concurrent refinement.
2040 _cg1r->init(card_counts_storage);
2041
2042 // 6843694 - ensure that the maximum region index can fit
2043 // in the remembered set structures.
2044 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2045 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2046
2047 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2048 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2049 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2050 "too many cards per region");
2051
2052 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2053
2054 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2055
2056 _g1h = this;
2057
2058 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2059 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2060
2061 // Create the ConcurrentMark data structure and thread.
2062 // (Must do this late, so that "max_regions" is defined.)
2063 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2064 if (_cm == NULL || !_cm->completed_initialization()) {
2065 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2066 return JNI_ENOMEM;
2067 }
2068 _cmThread = _cm->cmThread();
2069
2070 // Initialize the from_card cache structure of HeapRegionRemSet.
2071 HeapRegionRemSet::init_heap(max_regions());
2072
2073 // Now expand into the initial heap size.
2074 if (!expand(init_byte_size)) {
2075 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2076 return JNI_ENOMEM;
2077 }
2078
2079 // Perform any initialization actions delegated to the policy.
2080 g1_policy()->init();
2081
2082 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2083 SATB_Q_FL_lock,
2084 G1SATBProcessCompletedThreshold,
2085 Shared_SATB_Q_lock);
2086
2087 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2088 DirtyCardQ_CBL_mon,
2089 DirtyCardQ_FL_lock,
2090 concurrent_g1_refine()->yellow_zone(),
2091 concurrent_g1_refine()->red_zone(),
2092 Shared_DirtyCardQ_lock);
2093
2094 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2095 DirtyCardQ_CBL_mon,
2096 DirtyCardQ_FL_lock,
2097 -1, // never trigger processing
2098 -1, // no limit on length
2099 Shared_DirtyCardQ_lock,
2100 &JavaThread::dirty_card_queue_set());
2101
2102 // Initialize the card queue set used to hold cards containing
2103 // references into the collection set.
2104 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2105 DirtyCardQ_CBL_mon,
2106 DirtyCardQ_FL_lock,
2107 -1, // never trigger processing
2108 -1, // no limit on length
2109 Shared_DirtyCardQ_lock,
2110 &JavaThread::dirty_card_queue_set());
2111
2112 // In case we're keeping closure specialization stats, initialize those
2113 // counts and that mechanism.
2114 SpecializationStats::clear();
2115
2116 // Here we allocate the dummy HeapRegion that is required by the
2117 // G1AllocRegion class.
2118 HeapRegion* dummy_region = _hrm.get_dummy_region();
2119
2120 // We'll re-use the same region whether the alloc region will
2121 // require BOT updates or not and, if it doesn't, then a non-young
2122 // region will complain that it cannot support allocations without
2123 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2124 dummy_region->set_eden();
2125 // Make sure it's full.
2126 dummy_region->set_top(dummy_region->end());
2127 G1AllocRegion::setup(this, dummy_region);
2128
2129 _allocator->init_mutator_alloc_region();
2130
2131 // Do create of the monitoring and management support so that
2132 // values in the heap have been properly initialized.
2133 _g1mm = new G1MonitoringSupport(this);
2134
2135 G1StringDedup::initialize();
2136
2137 return JNI_OK;
2138 }
2139
2140 void G1CollectedHeap::stop() {
2141 // Stop all concurrent threads. We do this to make sure these threads
2142 // do not continue to execute and access resources (e.g. gclog_or_tty)
2143 // that are destroyed during shutdown.
2144 _cg1r->stop();
2145 _cmThread->stop();
2146 if (G1StringDedup::is_enabled()) {
2147 G1StringDedup::stop();
2148 }
2149 }
2150
2151 void G1CollectedHeap::clear_humongous_is_live_table() {
2152 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2153 _humongous_is_live.clear();
2154 }
2155
2156 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2157 return HeapRegion::max_region_size();
2158 }
2159
2160 void G1CollectedHeap::ref_processing_init() {
2161 // Reference processing in G1 currently works as follows:
2162 //
2163 // * There are two reference processor instances. One is
2164 // used to record and process discovered references
2165 // during concurrent marking; the other is used to
2166 // record and process references during STW pauses
2167 // (both full and incremental).
2168 // * Both ref processors need to 'span' the entire heap as
2169 // the regions in the collection set may be dotted around.
2170 //
2171 // * For the concurrent marking ref processor:
2172 // * Reference discovery is enabled at initial marking.
2173 // * Reference discovery is disabled and the discovered
2174 // references processed etc during remarking.
2175 // * Reference discovery is MT (see below).
2176 // * Reference discovery requires a barrier (see below).
2177 // * Reference processing may or may not be MT
2178 // (depending on the value of ParallelRefProcEnabled
2179 // and ParallelGCThreads).
2180 // * A full GC disables reference discovery by the CM
2181 // ref processor and abandons any entries on it's
2182 // discovered lists.
2183 //
2184 // * For the STW processor:
2185 // * Non MT discovery is enabled at the start of a full GC.
2186 // * Processing and enqueueing during a full GC is non-MT.
2187 // * During a full GC, references are processed after marking.
2188 //
2189 // * Discovery (may or may not be MT) is enabled at the start
2190 // of an incremental evacuation pause.
2191 // * References are processed near the end of a STW evacuation pause.
2192 // * For both types of GC:
2193 // * Discovery is atomic - i.e. not concurrent.
2194 // * Reference discovery will not need a barrier.
2195
2196 SharedHeap::ref_processing_init();
2197 MemRegion mr = reserved_region();
2198
2199 // Concurrent Mark ref processor
2200 _ref_processor_cm =
2201 new ReferenceProcessor(mr, // span
2202 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2203 // mt processing
2204 (int) ParallelGCThreads,
2205 // degree of mt processing
2206 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2207 // mt discovery
2208 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2209 // degree of mt discovery
2210 false,
2211 // Reference discovery is not atomic
2212 &_is_alive_closure_cm);
2213 // is alive closure
2214 // (for efficiency/performance)
2215
2216 // STW ref processor
2217 _ref_processor_stw =
2218 new ReferenceProcessor(mr, // span
2219 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2220 // mt processing
2221 MAX2((int)ParallelGCThreads, 1),
2222 // degree of mt processing
2223 (ParallelGCThreads > 1),
2224 // mt discovery
2225 MAX2((int)ParallelGCThreads, 1),
2226 // degree of mt discovery
2227 true,
2228 // Reference discovery is atomic
2229 &_is_alive_closure_stw);
2230 // is alive closure
2231 // (for efficiency/performance)
2232 }
2233
2234 size_t G1CollectedHeap::capacity() const {
2235 return _hrm.length() * HeapRegion::GrainBytes;
2236 }
2237
2238 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2239 assert(!hr->is_continues_humongous(), "pre-condition");
2240 hr->reset_gc_time_stamp();
2241 if (hr->is_starts_humongous()) {
2242 uint first_index = hr->hrm_index() + 1;
2243 uint last_index = hr->last_hc_index();
2244 for (uint i = first_index; i < last_index; i += 1) {
2245 HeapRegion* chr = region_at(i);
2246 assert(chr->is_continues_humongous(), "sanity");
2247 chr->reset_gc_time_stamp();
2248 }
2249 }
2250 }
2251
2252 #ifndef PRODUCT
2253 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2254 private:
2255 unsigned _gc_time_stamp;
2256 bool _failures;
2257
2258 public:
2259 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2260 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2261
2262 virtual bool doHeapRegion(HeapRegion* hr) {
2263 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2264 if (_gc_time_stamp != region_gc_time_stamp) {
2265 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2266 "expected %d", HR_FORMAT_PARAMS(hr),
2267 region_gc_time_stamp, _gc_time_stamp);
2268 _failures = true;
2269 }
2270 return false;
2271 }
2272
2273 bool failures() { return _failures; }
2274 };
2275
2276 void G1CollectedHeap::check_gc_time_stamps() {
2277 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2278 heap_region_iterate(&cl);
2279 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2280 }
2281 #endif // PRODUCT
2282
2283 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2284 DirtyCardQueue* into_cset_dcq,
2285 bool concurrent,
2286 uint worker_i) {
2287 // Clean cards in the hot card cache
2288 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2289 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2290
2291 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2292 int n_completed_buffers = 0;
2293 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2294 n_completed_buffers++;
2295 }
2296 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2297 dcqs.clear_n_completed_buffers();
2298 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2299 }
2300
2301
2302 // Computes the sum of the storage used by the various regions.
2303 size_t G1CollectedHeap::used() const {
2304 return _allocator->used();
2305 }
2306
2307 size_t G1CollectedHeap::used_unlocked() const {
2308 return _allocator->used_unlocked();
2309 }
2310
2311 class SumUsedClosure: public HeapRegionClosure {
2312 size_t _used;
2313 public:
2314 SumUsedClosure() : _used(0) {}
2315 bool doHeapRegion(HeapRegion* r) {
2316 if (!r->is_continues_humongous()) {
2317 _used += r->used();
2318 }
2319 return false;
2320 }
2321 size_t result() { return _used; }
2322 };
2323
2324 size_t G1CollectedHeap::recalculate_used() const {
2325 double recalculate_used_start = os::elapsedTime();
2326
2327 SumUsedClosure blk;
2328 heap_region_iterate(&blk);
2329
2330 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2331 return blk.result();
2332 }
2333
2334 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2335 switch (cause) {
2336 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2337 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2338 case GCCause::_g1_humongous_allocation: return true;
2339 default: return false;
2340 }
2341 }
2342
2343 #ifndef PRODUCT
2344 void G1CollectedHeap::allocate_dummy_regions() {
2345 // Let's fill up most of the region
2346 size_t word_size = HeapRegion::GrainWords - 1024;
2347 // And as a result the region we'll allocate will be humongous.
2348 guarantee(is_humongous(word_size), "sanity");
2349
2350 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2351 // Let's use the existing mechanism for the allocation
2352 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2353 AllocationContext::system());
2354 if (dummy_obj != NULL) {
2355 MemRegion mr(dummy_obj, word_size);
2356 CollectedHeap::fill_with_object(mr);
2357 } else {
2358 // If we can't allocate once, we probably cannot allocate
2359 // again. Let's get out of the loop.
2360 break;
2361 }
2362 }
2363 }
2364 #endif // !PRODUCT
2365
2366 void G1CollectedHeap::increment_old_marking_cycles_started() {
2367 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2368 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2369 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2370 _old_marking_cycles_started, _old_marking_cycles_completed));
2371
2372 _old_marking_cycles_started++;
2373 }
2374
2375 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2376 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2377
2378 // We assume that if concurrent == true, then the caller is a
2379 // concurrent thread that was joined the Suspendible Thread
2380 // Set. If there's ever a cheap way to check this, we should add an
2381 // assert here.
2382
2383 // Given that this method is called at the end of a Full GC or of a
2384 // concurrent cycle, and those can be nested (i.e., a Full GC can
2385 // interrupt a concurrent cycle), the number of full collections
2386 // completed should be either one (in the case where there was no
2387 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2388 // behind the number of full collections started.
2389
2390 // This is the case for the inner caller, i.e. a Full GC.
2391 assert(concurrent ||
2392 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2393 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2394 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2395 "is inconsistent with _old_marking_cycles_completed = %u",
2396 _old_marking_cycles_started, _old_marking_cycles_completed));
2397
2398 // This is the case for the outer caller, i.e. the concurrent cycle.
2399 assert(!concurrent ||
2400 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2401 err_msg("for outer caller (concurrent cycle): "
2402 "_old_marking_cycles_started = %u "
2403 "is inconsistent with _old_marking_cycles_completed = %u",
2404 _old_marking_cycles_started, _old_marking_cycles_completed));
2405
2406 _old_marking_cycles_completed += 1;
2407
2408 // We need to clear the "in_progress" flag in the CM thread before
2409 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2410 // is set) so that if a waiter requests another System.gc() it doesn't
2411 // incorrectly see that a marking cycle is still in progress.
2412 if (concurrent) {
2413 _cmThread->clear_in_progress();
2414 }
2415
2416 // This notify_all() will ensure that a thread that called
2417 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2418 // and it's waiting for a full GC to finish will be woken up. It is
2419 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2420 FullGCCount_lock->notify_all();
2421 }
2422
2423 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2424 _concurrent_cycle_started = true;
2425 _gc_timer_cm->register_gc_start(start_time);
2426
2427 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2428 trace_heap_before_gc(_gc_tracer_cm);
2429 }
2430
2431 void G1CollectedHeap::register_concurrent_cycle_end() {
2432 if (_concurrent_cycle_started) {
2433 if (_cm->has_aborted()) {
2434 _gc_tracer_cm->report_concurrent_mode_failure();
2435 }
2436
2437 _gc_timer_cm->register_gc_end();
2438 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2439
2440 // Clear state variables to prepare for the next concurrent cycle.
2441 _concurrent_cycle_started = false;
2442 _heap_summary_sent = false;
2443 }
2444 }
2445
2446 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2447 if (_concurrent_cycle_started) {
2448 // This function can be called when:
2449 // the cleanup pause is run
2450 // the concurrent cycle is aborted before the cleanup pause.
2451 // the concurrent cycle is aborted after the cleanup pause,
2452 // but before the concurrent cycle end has been registered.
2453 // Make sure that we only send the heap information once.
2454 if (!_heap_summary_sent) {
2455 trace_heap_after_gc(_gc_tracer_cm);
2456 _heap_summary_sent = true;
2457 }
2458 }
2459 }
2460
2461 G1YCType G1CollectedHeap::yc_type() {
2462 bool is_young = g1_policy()->gcs_are_young();
2463 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2464 bool is_during_mark = mark_in_progress();
2465
2466 if (is_initial_mark) {
2467 return InitialMark;
2468 } else if (is_during_mark) {
2469 return DuringMark;
2470 } else if (is_young) {
2471 return Normal;
2472 } else {
2473 return Mixed;
2474 }
2475 }
2476
2477 void G1CollectedHeap::collect(GCCause::Cause cause) {
2478 assert_heap_not_locked();
2479
2480 unsigned int gc_count_before;
2481 unsigned int old_marking_count_before;
2482 bool retry_gc;
2483
2484 do {
2485 retry_gc = false;
2486
2487 {
2488 MutexLocker ml(Heap_lock);
2489
2490 // Read the GC count while holding the Heap_lock
2491 gc_count_before = total_collections();
2492 old_marking_count_before = _old_marking_cycles_started;
2493 }
2494
2495 if (should_do_concurrent_full_gc(cause)) {
2496 // Schedule an initial-mark evacuation pause that will start a
2497 // concurrent cycle. We're setting word_size to 0 which means that
2498 // we are not requesting a post-GC allocation.
2499 VM_G1IncCollectionPause op(gc_count_before,
2500 0, /* word_size */
2501 true, /* should_initiate_conc_mark */
2502 g1_policy()->max_pause_time_ms(),
2503 cause);
2504 op.set_allocation_context(AllocationContext::current());
2505
2506 VMThread::execute(&op);
2507 if (!op.pause_succeeded()) {
2508 if (old_marking_count_before == _old_marking_cycles_started) {
2509 retry_gc = op.should_retry_gc();
2510 } else {
2511 // A Full GC happened while we were trying to schedule the
2512 // initial-mark GC. No point in starting a new cycle given
2513 // that the whole heap was collected anyway.
2514 }
2515
2516 if (retry_gc) {
2517 if (GC_locker::is_active_and_needs_gc()) {
2518 GC_locker::stall_until_clear();
2519 }
2520 }
2521 }
2522 } else {
2523 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2524 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2525
2526 // Schedule a standard evacuation pause. We're setting word_size
2527 // to 0 which means that we are not requesting a post-GC allocation.
2528 VM_G1IncCollectionPause op(gc_count_before,
2529 0, /* word_size */
2530 false, /* should_initiate_conc_mark */
2531 g1_policy()->max_pause_time_ms(),
2532 cause);
2533 VMThread::execute(&op);
2534 } else {
2535 // Schedule a Full GC.
2536 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2537 VMThread::execute(&op);
2538 }
2539 }
2540 } while (retry_gc);
2541 }
2542
2543 bool G1CollectedHeap::is_in(const void* p) const {
2544 if (_hrm.reserved().contains(p)) {
2545 // Given that we know that p is in the reserved space,
2546 // heap_region_containing_raw() should successfully
2547 // return the containing region.
2548 HeapRegion* hr = heap_region_containing_raw(p);
2549 return hr->is_in(p);
2550 } else {
2551 return false;
2552 }
2553 }
2554
2555 #ifdef ASSERT
2556 bool G1CollectedHeap::is_in_exact(const void* p) const {
2557 bool contains = reserved_region().contains(p);
2558 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2559 if (contains && available) {
2560 return true;
2561 } else {
2562 return false;
2563 }
2564 }
2565 #endif
2566
2567 // Iteration functions.
2568
2569 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2570
2571 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2572 ExtendedOopClosure* _cl;
2573 public:
2574 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2575 bool doHeapRegion(HeapRegion* r) {
2576 if (!r->is_continues_humongous()) {
2577 r->oop_iterate(_cl);
2578 }
2579 return false;
2580 }
2581 };
2582
2583 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2584 IterateOopClosureRegionClosure blk(cl);
2585 heap_region_iterate(&blk);
2586 }
2587
2588 // Iterates an ObjectClosure over all objects within a HeapRegion.
2589
2590 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2591 ObjectClosure* _cl;
2592 public:
2593 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2594 bool doHeapRegion(HeapRegion* r) {
2595 if (!r->is_continues_humongous()) {
2596 r->object_iterate(_cl);
2597 }
2598 return false;
2599 }
2600 };
2601
2602 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2603 IterateObjectClosureRegionClosure blk(cl);
2604 heap_region_iterate(&blk);
2605 }
2606
2607 // Calls a SpaceClosure on a HeapRegion.
2608
2609 class SpaceClosureRegionClosure: public HeapRegionClosure {
2610 SpaceClosure* _cl;
2611 public:
2612 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2613 bool doHeapRegion(HeapRegion* r) {
2614 _cl->do_space(r);
2615 return false;
2616 }
2617 };
2618
2619 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2620 SpaceClosureRegionClosure blk(cl);
2621 heap_region_iterate(&blk);
2622 }
2623
2624 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2625 _hrm.iterate(cl);
2626 }
2627
2628 void
2629 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2630 uint worker_id,
2631 HeapRegionClaimer *hrclaimer) const {
2632 _hrm.par_iterate(cl, worker_id, hrclaimer);
2633 }
2634
2635 // Clear the cached CSet starting regions and (more importantly)
2636 // the time stamps. Called when we reset the GC time stamp.
2637 void G1CollectedHeap::clear_cset_start_regions() {
2638 assert(_worker_cset_start_region != NULL, "sanity");
2639 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2640
2641 int n_queues = MAX2((int)ParallelGCThreads, 1);
2642 for (int i = 0; i < n_queues; i++) {
2643 _worker_cset_start_region[i] = NULL;
2644 _worker_cset_start_region_time_stamp[i] = 0;
2645 }
2646 }
2647
2648 // Given the id of a worker, obtain or calculate a suitable
2649 // starting region for iterating over the current collection set.
2650 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2651 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2652
2653 HeapRegion* result = NULL;
2654 unsigned gc_time_stamp = get_gc_time_stamp();
2655
2656 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2657 // Cached starting region for current worker was set
2658 // during the current pause - so it's valid.
2659 // Note: the cached starting heap region may be NULL
2660 // (when the collection set is empty).
2661 result = _worker_cset_start_region[worker_i];
2662 assert(result == NULL || result->in_collection_set(), "sanity");
2663 return result;
2664 }
2665
2666 // The cached entry was not valid so let's calculate
2667 // a suitable starting heap region for this worker.
2668
2669 // We want the parallel threads to start their collection
2670 // set iteration at different collection set regions to
2671 // avoid contention.
2672 // If we have:
2673 // n collection set regions
2674 // p threads
2675 // Then thread t will start at region floor ((t * n) / p)
2676
2677 result = g1_policy()->collection_set();
2678 if (G1CollectedHeap::use_parallel_gc_threads()) {
2679 uint cs_size = g1_policy()->cset_region_length();
2680 uint active_workers = workers()->active_workers();
2681 assert(UseDynamicNumberOfGCThreads ||
2682 active_workers == workers()->total_workers(),
2683 "Unless dynamic should use total workers");
2684
2685 uint end_ind = (cs_size * worker_i) / active_workers;
2686 uint start_ind = 0;
2687
2688 if (worker_i > 0 &&
2689 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2690 // Previous workers starting region is valid
2691 // so let's iterate from there
2692 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2693 result = _worker_cset_start_region[worker_i - 1];
2694 }
2695
2696 for (uint i = start_ind; i < end_ind; i++) {
2697 result = result->next_in_collection_set();
2698 }
2699 }
2700
2701 // Note: the calculated starting heap region may be NULL
2702 // (when the collection set is empty).
2703 assert(result == NULL || result->in_collection_set(), "sanity");
2704 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2705 "should be updated only once per pause");
2706 _worker_cset_start_region[worker_i] = result;
2707 OrderAccess::storestore();
2708 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2709 return result;
2710 }
2711
2712 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2713 HeapRegion* r = g1_policy()->collection_set();
2714 while (r != NULL) {
2715 HeapRegion* next = r->next_in_collection_set();
2716 if (cl->doHeapRegion(r)) {
2717 cl->incomplete();
2718 return;
2719 }
2720 r = next;
2721 }
2722 }
2723
2724 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2725 HeapRegionClosure *cl) {
2726 if (r == NULL) {
2727 // The CSet is empty so there's nothing to do.
2728 return;
2729 }
2730
2731 assert(r->in_collection_set(),
2732 "Start region must be a member of the collection set.");
2733 HeapRegion* cur = r;
2734 while (cur != NULL) {
2735 HeapRegion* next = cur->next_in_collection_set();
2736 if (cl->doHeapRegion(cur) && false) {
2737 cl->incomplete();
2738 return;
2739 }
2740 cur = next;
2741 }
2742 cur = g1_policy()->collection_set();
2743 while (cur != r) {
2744 HeapRegion* next = cur->next_in_collection_set();
2745 if (cl->doHeapRegion(cur) && false) {
2746 cl->incomplete();
2747 return;
2748 }
2749 cur = next;
2750 }
2751 }
2752
2753 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2754 HeapRegion* result = _hrm.next_region_in_heap(from);
2755 while (result != NULL && result->is_humongous()) {
2756 result = _hrm.next_region_in_heap(result);
2757 }
2758 return result;
2759 }
2760
2761 Space* G1CollectedHeap::space_containing(const void* addr) const {
2762 return heap_region_containing(addr);
2763 }
2764
2765 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2766 Space* sp = space_containing(addr);
2767 return sp->block_start(addr);
2768 }
2769
2770 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2771 Space* sp = space_containing(addr);
2772 return sp->block_size(addr);
2773 }
2774
2775 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2776 Space* sp = space_containing(addr);
2777 return sp->block_is_obj(addr);
2778 }
2779
2780 bool G1CollectedHeap::supports_tlab_allocation() const {
2781 return true;
2782 }
2783
2784 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2785 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2786 }
2787
2788 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2789 return young_list()->eden_used_bytes();
2790 }
2791
2792 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2793 // must be smaller than the humongous object limit.
2794 size_t G1CollectedHeap::max_tlab_size() const {
2795 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2796 }
2797
2798 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2799 // Return the remaining space in the cur alloc region, but not less than
2800 // the min TLAB size.
2801
2802 // Also, this value can be at most the humongous object threshold,
2803 // since we can't allow tlabs to grow big enough to accommodate
2804 // humongous objects.
2805
2806 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2807 size_t max_tlab = max_tlab_size() * wordSize;
2808 if (hr == NULL) {
2809 return max_tlab;
2810 } else {
2811 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2812 }
2813 }
2814
2815 size_t G1CollectedHeap::max_capacity() const {
2816 return _hrm.reserved().byte_size();
2817 }
2818
2819 jlong G1CollectedHeap::millis_since_last_gc() {
2820 // assert(false, "NYI");
2821 return 0;
2822 }
2823
2824 void G1CollectedHeap::prepare_for_verify() {
2825 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2826 ensure_parsability(false);
2827 }
2828 g1_rem_set()->prepare_for_verify();
2829 }
2830
2831 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2832 VerifyOption vo) {
2833 switch (vo) {
2834 case VerifyOption_G1UsePrevMarking:
2835 return hr->obj_allocated_since_prev_marking(obj);
2836 case VerifyOption_G1UseNextMarking:
2837 return hr->obj_allocated_since_next_marking(obj);
2838 case VerifyOption_G1UseMarkWord:
2839 return false;
2840 default:
2841 ShouldNotReachHere();
2842 }
2843 return false; // keep some compilers happy
2844 }
2845
2846 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2847 switch (vo) {
2848 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2849 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2850 case VerifyOption_G1UseMarkWord: return NULL;
2851 default: ShouldNotReachHere();
2852 }
2853 return NULL; // keep some compilers happy
2854 }
2855
2856 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2857 switch (vo) {
2858 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2859 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2860 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2861 default: ShouldNotReachHere();
2862 }
2863 return false; // keep some compilers happy
2864 }
2865
2866 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2867 switch (vo) {
2868 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2869 case VerifyOption_G1UseNextMarking: return "NTAMS";
2870 case VerifyOption_G1UseMarkWord: return "NONE";
2871 default: ShouldNotReachHere();
2872 }
2873 return NULL; // keep some compilers happy
2874 }
2875
2876 class VerifyRootsClosure: public OopClosure {
2877 private:
2878 G1CollectedHeap* _g1h;
2879 VerifyOption _vo;
2880 bool _failures;
2881 public:
2882 // _vo == UsePrevMarking -> use "prev" marking information,
2883 // _vo == UseNextMarking -> use "next" marking information,
2884 // _vo == UseMarkWord -> use mark word from object header.
2885 VerifyRootsClosure(VerifyOption vo) :
2886 _g1h(G1CollectedHeap::heap()),
2887 _vo(vo),
2888 _failures(false) { }
2889
2890 bool failures() { return _failures; }
2891
2892 template <class T> void do_oop_nv(T* p) {
2893 T heap_oop = oopDesc::load_heap_oop(p);
2894 if (!oopDesc::is_null(heap_oop)) {
2895 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2896 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2897 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2898 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2899 if (_vo == VerifyOption_G1UseMarkWord) {
2900 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2901 }
2902 obj->print_on(gclog_or_tty);
2903 _failures = true;
2904 }
2905 }
2906 }
2907
2908 void do_oop(oop* p) { do_oop_nv(p); }
2909 void do_oop(narrowOop* p) { do_oop_nv(p); }
2910 };
2911
2912 class G1VerifyCodeRootOopClosure: public OopClosure {
2913 G1CollectedHeap* _g1h;
2914 OopClosure* _root_cl;
2915 nmethod* _nm;
2916 VerifyOption _vo;
2917 bool _failures;
2918
2919 template <class T> void do_oop_work(T* p) {
2920 // First verify that this root is live
2921 _root_cl->do_oop(p);
2922
2923 if (!G1VerifyHeapRegionCodeRoots) {
2924 // We're not verifying the code roots attached to heap region.
2925 return;
2926 }
2927
2928 // Don't check the code roots during marking verification in a full GC
2929 if (_vo == VerifyOption_G1UseMarkWord) {
2930 return;
2931 }
2932
2933 // Now verify that the current nmethod (which contains p) is
2934 // in the code root list of the heap region containing the
2935 // object referenced by p.
2936
2937 T heap_oop = oopDesc::load_heap_oop(p);
2938 if (!oopDesc::is_null(heap_oop)) {
2939 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2940
2941 // Now fetch the region containing the object
2942 HeapRegion* hr = _g1h->heap_region_containing(obj);
2943 HeapRegionRemSet* hrrs = hr->rem_set();
2944 // Verify that the strong code root list for this region
2945 // contains the nmethod
2946 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2947 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2948 "from nmethod "PTR_FORMAT" not in strong "
2949 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2950 p, _nm, hr->bottom(), hr->end());
2951 _failures = true;
2952 }
2953 }
2954 }
2955
2956 public:
2957 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2958 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2959
2960 void do_oop(oop* p) { do_oop_work(p); }
2961 void do_oop(narrowOop* p) { do_oop_work(p); }
2962
2963 void set_nmethod(nmethod* nm) { _nm = nm; }
2964 bool failures() { return _failures; }
2965 };
2966
2967 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2968 G1VerifyCodeRootOopClosure* _oop_cl;
2969
2970 public:
2971 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2972 _oop_cl(oop_cl) {}
2973
2974 void do_code_blob(CodeBlob* cb) {
2975 nmethod* nm = cb->as_nmethod_or_null();
2976 if (nm != NULL) {
2977 _oop_cl->set_nmethod(nm);
2978 nm->oops_do(_oop_cl);
2979 }
2980 }
2981 };
2982
2983 class YoungRefCounterClosure : public OopClosure {
2984 G1CollectedHeap* _g1h;
2985 int _count;
2986 public:
2987 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2988 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2989 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2990
2991 int count() { return _count; }
2992 void reset_count() { _count = 0; };
2993 };
2994
2995 class VerifyKlassClosure: public KlassClosure {
2996 YoungRefCounterClosure _young_ref_counter_closure;
2997 OopClosure *_oop_closure;
2998 public:
2999 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3000 void do_klass(Klass* k) {
3001 k->oops_do(_oop_closure);
3002
3003 _young_ref_counter_closure.reset_count();
3004 k->oops_do(&_young_ref_counter_closure);
3005 if (_young_ref_counter_closure.count() > 0) {
3006 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3007 }
3008 }
3009 };
3010
3011 class VerifyLivenessOopClosure: public OopClosure {
3012 G1CollectedHeap* _g1h;
3013 VerifyOption _vo;
3014 public:
3015 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3016 _g1h(g1h), _vo(vo)
3017 { }
3018 void do_oop(narrowOop *p) { do_oop_work(p); }
3019 void do_oop( oop *p) { do_oop_work(p); }
3020
3021 template <class T> void do_oop_work(T *p) {
3022 oop obj = oopDesc::load_decode_heap_oop(p);
3023 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3024 "Dead object referenced by a not dead object");
3025 }
3026 };
3027
3028 class VerifyObjsInRegionClosure: public ObjectClosure {
3029 private:
3030 G1CollectedHeap* _g1h;
3031 size_t _live_bytes;
3032 HeapRegion *_hr;
3033 VerifyOption _vo;
3034 public:
3035 // _vo == UsePrevMarking -> use "prev" marking information,
3036 // _vo == UseNextMarking -> use "next" marking information,
3037 // _vo == UseMarkWord -> use mark word from object header.
3038 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3039 : _live_bytes(0), _hr(hr), _vo(vo) {
3040 _g1h = G1CollectedHeap::heap();
3041 }
3042 void do_object(oop o) {
3043 VerifyLivenessOopClosure isLive(_g1h, _vo);
3044 assert(o != NULL, "Huh?");
3045 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3046 // If the object is alive according to the mark word,
3047 // then verify that the marking information agrees.
3048 // Note we can't verify the contra-positive of the
3049 // above: if the object is dead (according to the mark
3050 // word), it may not be marked, or may have been marked
3051 // but has since became dead, or may have been allocated
3052 // since the last marking.
3053 if (_vo == VerifyOption_G1UseMarkWord) {
3054 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3055 }
3056
3057 o->oop_iterate_no_header(&isLive);
3058 if (!_hr->obj_allocated_since_prev_marking(o)) {
3059 size_t obj_size = o->size(); // Make sure we don't overflow
3060 _live_bytes += (obj_size * HeapWordSize);
3061 }
3062 }
3063 }
3064 size_t live_bytes() { return _live_bytes; }
3065 };
3066
3067 class PrintObjsInRegionClosure : public ObjectClosure {
3068 HeapRegion *_hr;
3069 G1CollectedHeap *_g1;
3070 public:
3071 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3072 _g1 = G1CollectedHeap::heap();
3073 };
3074
3075 void do_object(oop o) {
3076 if (o != NULL) {
3077 HeapWord *start = (HeapWord *) o;
3078 size_t word_sz = o->size();
3079 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3080 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3081 (void*) o, word_sz,
3082 _g1->isMarkedPrev(o),
3083 _g1->isMarkedNext(o),
3084 _hr->obj_allocated_since_prev_marking(o));
3085 HeapWord *end = start + word_sz;
3086 HeapWord *cur;
3087 int *val;
3088 for (cur = start; cur < end; cur++) {
3089 val = (int *) cur;
3090 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3091 }
3092 }
3093 }
3094 };
3095
3096 class VerifyRegionClosure: public HeapRegionClosure {
3097 private:
3098 bool _par;
3099 VerifyOption _vo;
3100 bool _failures;
3101 public:
3102 // _vo == UsePrevMarking -> use "prev" marking information,
3103 // _vo == UseNextMarking -> use "next" marking information,
3104 // _vo == UseMarkWord -> use mark word from object header.
3105 VerifyRegionClosure(bool par, VerifyOption vo)
3106 : _par(par),
3107 _vo(vo),
3108 _failures(false) {}
3109
3110 bool failures() {
3111 return _failures;
3112 }
3113
3114 bool doHeapRegion(HeapRegion* r) {
3115 if (!r->is_continues_humongous()) {
3116 bool failures = false;
3117 r->verify(_vo, &failures);
3118 if (failures) {
3119 _failures = true;
3120 } else {
3121 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3122 r->object_iterate(¬_dead_yet_cl);
3123 if (_vo != VerifyOption_G1UseNextMarking) {
3124 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3125 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3126 "max_live_bytes "SIZE_FORMAT" "
3127 "< calculated "SIZE_FORMAT,
3128 r->bottom(), r->end(),
3129 r->max_live_bytes(),
3130 not_dead_yet_cl.live_bytes());
3131 _failures = true;
3132 }
3133 } else {
3134 // When vo == UseNextMarking we cannot currently do a sanity
3135 // check on the live bytes as the calculation has not been
3136 // finalized yet.
3137 }
3138 }
3139 }
3140 return false; // stop the region iteration if we hit a failure
3141 }
3142 };
3143
3144 // This is the task used for parallel verification of the heap regions
3145
3146 class G1ParVerifyTask: public AbstractGangTask {
3147 private:
3148 G1CollectedHeap* _g1h;
3149 VerifyOption _vo;
3150 bool _failures;
3151 HeapRegionClaimer _hrclaimer;
3152
3153 public:
3154 // _vo == UsePrevMarking -> use "prev" marking information,
3155 // _vo == UseNextMarking -> use "next" marking information,
3156 // _vo == UseMarkWord -> use mark word from object header.
3157 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3158 AbstractGangTask("Parallel verify task"),
3159 _g1h(g1h),
3160 _vo(vo),
3161 _failures(false),
3162 _hrclaimer(g1h->workers()->active_workers()) {}
3163
3164 bool failures() {
3165 return _failures;
3166 }
3167
3168 void work(uint worker_id) {
3169 HandleMark hm;
3170 VerifyRegionClosure blk(true, _vo);
3171 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3172 if (blk.failures()) {
3173 _failures = true;
3174 }
3175 }
3176 };
3177
3178 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3179 if (SafepointSynchronize::is_at_safepoint()) {
3180 assert(Thread::current()->is_VM_thread(),
3181 "Expected to be executed serially by the VM thread at this point");
3182
3183 if (!silent) { gclog_or_tty->print("Roots "); }
3184 VerifyRootsClosure rootsCl(vo);
3185 VerifyKlassClosure klassCl(this, &rootsCl);
3186 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3187
3188 // We apply the relevant closures to all the oops in the
3189 // system dictionary, class loader data graph, the string table
3190 // and the nmethods in the code cache.
3191 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3192 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3193
3194 process_all_roots(true, // activate StrongRootsScope
3195 SO_AllCodeCache, // roots scanning options
3196 &rootsCl,
3197 &cldCl,
3198 &blobsCl);
3199
3200 bool failures = rootsCl.failures() || codeRootsCl.failures();
3201
3202 if (vo != VerifyOption_G1UseMarkWord) {
3203 // If we're verifying during a full GC then the region sets
3204 // will have been torn down at the start of the GC. Therefore
3205 // verifying the region sets will fail. So we only verify
3206 // the region sets when not in a full GC.
3207 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3208 verify_region_sets();
3209 }
3210
3211 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3212 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3213
3214 G1ParVerifyTask task(this, vo);
3215 assert(UseDynamicNumberOfGCThreads ||
3216 workers()->active_workers() == workers()->total_workers(),
3217 "If not dynamic should be using all the workers");
3218 int n_workers = workers()->active_workers();
3219 set_par_threads(n_workers);
3220 workers()->run_task(&task);
3221 set_par_threads(0);
3222 if (task.failures()) {
3223 failures = true;
3224 }
3225
3226 } else {
3227 VerifyRegionClosure blk(false, vo);
3228 heap_region_iterate(&blk);
3229 if (blk.failures()) {
3230 failures = true;
3231 }
3232 }
3233 if (!silent) gclog_or_tty->print("RemSet ");
3234 rem_set()->verify();
3235
3236 if (G1StringDedup::is_enabled()) {
3237 if (!silent) gclog_or_tty->print("StrDedup ");
3238 G1StringDedup::verify();
3239 }
3240
3241 if (failures) {
3242 gclog_or_tty->print_cr("Heap:");
3243 // It helps to have the per-region information in the output to
3244 // help us track down what went wrong. This is why we call
3245 // print_extended_on() instead of print_on().
3246 print_extended_on(gclog_or_tty);
3247 gclog_or_tty->cr();
3248 #ifndef PRODUCT
3249 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3250 concurrent_mark()->print_reachable("at-verification-failure",
3251 vo, false /* all */);
3252 }
3253 #endif
3254 gclog_or_tty->flush();
3255 }
3256 guarantee(!failures, "there should not have been any failures");
3257 } else {
3258 if (!silent) {
3259 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3260 if (G1StringDedup::is_enabled()) {
3261 gclog_or_tty->print(", StrDedup");
3262 }
3263 gclog_or_tty->print(") ");
3264 }
3265 }
3266 }
3267
3268 void G1CollectedHeap::verify(bool silent) {
3269 verify(silent, VerifyOption_G1UsePrevMarking);
3270 }
3271
3272 double G1CollectedHeap::verify(bool guard, const char* msg) {
3273 double verify_time_ms = 0.0;
3274
3275 if (guard && total_collections() >= VerifyGCStartAt) {
3276 double verify_start = os::elapsedTime();
3277 HandleMark hm; // Discard invalid handles created during verification
3278 prepare_for_verify();
3279 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3280 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3281 }
3282
3283 return verify_time_ms;
3284 }
3285
3286 void G1CollectedHeap::verify_before_gc() {
3287 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3288 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3289 }
3290
3291 void G1CollectedHeap::verify_after_gc() {
3292 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3293 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3294 }
3295
3296 class PrintRegionClosure: public HeapRegionClosure {
3297 outputStream* _st;
3298 public:
3299 PrintRegionClosure(outputStream* st) : _st(st) {}
3300 bool doHeapRegion(HeapRegion* r) {
3301 r->print_on(_st);
3302 return false;
3303 }
3304 };
3305
3306 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3307 const HeapRegion* hr,
3308 const VerifyOption vo) const {
3309 switch (vo) {
3310 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3311 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3312 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3313 default: ShouldNotReachHere();
3314 }
3315 return false; // keep some compilers happy
3316 }
3317
3318 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3319 const VerifyOption vo) const {
3320 switch (vo) {
3321 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3322 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3323 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3324 default: ShouldNotReachHere();
3325 }
3326 return false; // keep some compilers happy
3327 }
3328
3329 void G1CollectedHeap::print_on(outputStream* st) const {
3330 st->print(" %-20s", "garbage-first heap");
3331 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3332 capacity()/K, used_unlocked()/K);
3333 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3334 _hrm.reserved().start(),
3335 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3336 _hrm.reserved().end());
3337 st->cr();
3338 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3339 uint young_regions = _young_list->length();
3340 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3341 (size_t) young_regions * HeapRegion::GrainBytes / K);
3342 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3343 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3344 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3345 st->cr();
3346 MetaspaceAux::print_on(st);
3347 }
3348
3349 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3350 print_on(st);
3351
3352 // Print the per-region information.
3353 st->cr();
3354 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3355 "HS=humongous(starts), HC=humongous(continues), "
3356 "CS=collection set, F=free, TS=gc time stamp, "
3357 "PTAMS=previous top-at-mark-start, "
3358 "NTAMS=next top-at-mark-start)");
3359 PrintRegionClosure blk(st);
3360 heap_region_iterate(&blk);
3361 }
3362
3363 void G1CollectedHeap::print_on_error(outputStream* st) const {
3364 this->CollectedHeap::print_on_error(st);
3365
3366 if (_cm != NULL) {
3367 st->cr();
3368 _cm->print_on_error(st);
3369 }
3370 }
3371
3372 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3373 if (G1CollectedHeap::use_parallel_gc_threads()) {
3374 workers()->print_worker_threads_on(st);
3375 }
3376 _cmThread->print_on(st);
3377 st->cr();
3378 _cm->print_worker_threads_on(st);
3379 _cg1r->print_worker_threads_on(st);
3380 if (G1StringDedup::is_enabled()) {
3381 G1StringDedup::print_worker_threads_on(st);
3382 }
3383 }
3384
3385 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3386 if (G1CollectedHeap::use_parallel_gc_threads()) {
3387 workers()->threads_do(tc);
3388 }
3389 tc->do_thread(_cmThread);
3390 _cg1r->threads_do(tc);
3391 if (G1StringDedup::is_enabled()) {
3392 G1StringDedup::threads_do(tc);
3393 }
3394 }
3395
3396 void G1CollectedHeap::print_tracing_info() const {
3397 // We'll overload this to mean "trace GC pause statistics."
3398 if (TraceYoungGenTime || TraceOldGenTime) {
3399 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3400 // to that.
3401 g1_policy()->print_tracing_info();
3402 }
3403 if (G1SummarizeRSetStats) {
3404 g1_rem_set()->print_summary_info();
3405 }
3406 if (G1SummarizeConcMark) {
3407 concurrent_mark()->print_summary_info();
3408 }
3409 g1_policy()->print_yg_surv_rate_info();
3410 SpecializationStats::print();
3411 }
3412
3413 #ifndef PRODUCT
3414 // Helpful for debugging RSet issues.
3415
3416 class PrintRSetsClosure : public HeapRegionClosure {
3417 private:
3418 const char* _msg;
3419 size_t _occupied_sum;
3420
3421 public:
3422 bool doHeapRegion(HeapRegion* r) {
3423 HeapRegionRemSet* hrrs = r->rem_set();
3424 size_t occupied = hrrs->occupied();
3425 _occupied_sum += occupied;
3426
3427 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3428 HR_FORMAT_PARAMS(r));
3429 if (occupied == 0) {
3430 gclog_or_tty->print_cr(" RSet is empty");
3431 } else {
3432 hrrs->print();
3433 }
3434 gclog_or_tty->print_cr("----------");
3435 return false;
3436 }
3437
3438 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3439 gclog_or_tty->cr();
3440 gclog_or_tty->print_cr("========================================");
3441 gclog_or_tty->print_cr("%s", msg);
3442 gclog_or_tty->cr();
3443 }
3444
3445 ~PrintRSetsClosure() {
3446 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3447 gclog_or_tty->print_cr("========================================");
3448 gclog_or_tty->cr();
3449 }
3450 };
3451
3452 void G1CollectedHeap::print_cset_rsets() {
3453 PrintRSetsClosure cl("Printing CSet RSets");
3454 collection_set_iterate(&cl);
3455 }
3456
3457 void G1CollectedHeap::print_all_rsets() {
3458 PrintRSetsClosure cl("Printing All RSets");;
3459 heap_region_iterate(&cl);
3460 }
3461 #endif // PRODUCT
3462
3463 G1CollectedHeap* G1CollectedHeap::heap() {
3464 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3465 "not a garbage-first heap");
3466 return _g1h;
3467 }
3468
3469 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3470 // always_do_update_barrier = false;
3471 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3472 // Fill TLAB's and such
3473 accumulate_statistics_all_tlabs();
3474 ensure_parsability(true);
3475
3476 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3477 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3478 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3479 }
3480 }
3481
3482 void G1CollectedHeap::gc_epilogue(bool full) {
3483
3484 if (G1SummarizeRSetStats &&
3485 (G1SummarizeRSetStatsPeriod > 0) &&
3486 // we are at the end of the GC. Total collections has already been increased.
3487 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3488 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3489 }
3490
3491 // FIXME: what is this about?
3492 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3493 // is set.
3494 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3495 "derived pointer present"));
3496 // always_do_update_barrier = true;
3497
3498 resize_all_tlabs();
3499 allocation_context_stats().update(full);
3500
3501 // We have just completed a GC. Update the soft reference
3502 // policy with the new heap occupancy
3503 Universe::update_heap_info_at_gc();
3504 }
3505
3506 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3507 unsigned int gc_count_before,
3508 bool* succeeded,
3509 GCCause::Cause gc_cause) {
3510 assert_heap_not_locked_and_not_at_safepoint();
3511 g1_policy()->record_stop_world_start();
3512 VM_G1IncCollectionPause op(gc_count_before,
3513 word_size,
3514 false, /* should_initiate_conc_mark */
3515 g1_policy()->max_pause_time_ms(),
3516 gc_cause);
3517
3518 op.set_allocation_context(AllocationContext::current());
3519 VMThread::execute(&op);
3520
3521 HeapWord* result = op.result();
3522 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3523 assert(result == NULL || ret_succeeded,
3524 "the result should be NULL if the VM did not succeed");
3525 *succeeded = ret_succeeded;
3526
3527 assert_heap_not_locked();
3528 return result;
3529 }
3530
3531 void
3532 G1CollectedHeap::doConcurrentMark() {
3533 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3534 if (!_cmThread->in_progress()) {
3535 _cmThread->set_started();
3536 CGC_lock->notify();
3537 }
3538 }
3539
3540 size_t G1CollectedHeap::pending_card_num() {
3541 size_t extra_cards = 0;
3542 JavaThread *curr = Threads::first();
3543 while (curr != NULL) {
3544 DirtyCardQueue& dcq = curr->dirty_card_queue();
3545 extra_cards += dcq.size();
3546 curr = curr->next();
3547 }
3548 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3549 size_t buffer_size = dcqs.buffer_size();
3550 size_t buffer_num = dcqs.completed_buffers_num();
3551
3552 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3553 // in bytes - not the number of 'entries'. We need to convert
3554 // into a number of cards.
3555 return (buffer_size * buffer_num + extra_cards) / oopSize;
3556 }
3557
3558 size_t G1CollectedHeap::cards_scanned() {
3559 return g1_rem_set()->cardsScanned();
3560 }
3561
3562 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3563 HeapRegion* region = region_at(index);
3564 assert(region->is_starts_humongous(), "Must start a humongous object");
3565 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3566 }
3567
3568 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3569 private:
3570 size_t _total_humongous;
3571 size_t _candidate_humongous;
3572 public:
3573 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3574 }
3575
3576 virtual bool doHeapRegion(HeapRegion* r) {
3577 if (!r->is_starts_humongous()) {
3578 return false;
3579 }
3580 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3581
3582 uint region_idx = r->hrm_index();
3583 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3584 // Is_candidate already filters out humongous regions with some remembered set.
3585 // This will not lead to humongous object that we mistakenly keep alive because
3586 // during young collection the remembered sets will only be added to.
3587 if (is_candidate) {
3588 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3589 _candidate_humongous++;
3590 }
3591 _total_humongous++;
3592
3593 return false;
3594 }
3595
3596 size_t total_humongous() const { return _total_humongous; }
3597 size_t candidate_humongous() const { return _candidate_humongous; }
3598 };
3599
3600 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3601 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3602 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3603 return;
3604 }
3605
3606 RegisterHumongousWithInCSetFastTestClosure cl;
3607 heap_region_iterate(&cl);
3608 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3609 cl.candidate_humongous());
3610 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3611
3612 if (_has_humongous_reclaim_candidates) {
3613 clear_humongous_is_live_table();
3614 }
3615 }
3616
3617 void
3618 G1CollectedHeap::setup_surviving_young_words() {
3619 assert(_surviving_young_words == NULL, "pre-condition");
3620 uint array_length = g1_policy()->young_cset_region_length();
3621 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3622 if (_surviving_young_words == NULL) {
3623 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3624 "Not enough space for young surv words summary.");
3625 }
3626 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3627 #ifdef ASSERT
3628 for (uint i = 0; i < array_length; ++i) {
3629 assert( _surviving_young_words[i] == 0, "memset above" );
3630 }
3631 #endif // !ASSERT
3632 }
3633
3634 void
3635 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3636 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3637 uint array_length = g1_policy()->young_cset_region_length();
3638 for (uint i = 0; i < array_length; ++i) {
3639 _surviving_young_words[i] += surv_young_words[i];
3640 }
3641 }
3642
3643 void
3644 G1CollectedHeap::cleanup_surviving_young_words() {
3645 guarantee( _surviving_young_words != NULL, "pre-condition" );
3646 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3647 _surviving_young_words = NULL;
3648 }
3649
3650 #ifdef ASSERT
3651 class VerifyCSetClosure: public HeapRegionClosure {
3652 public:
3653 bool doHeapRegion(HeapRegion* hr) {
3654 // Here we check that the CSet region's RSet is ready for parallel
3655 // iteration. The fields that we'll verify are only manipulated
3656 // when the region is part of a CSet and is collected. Afterwards,
3657 // we reset these fields when we clear the region's RSet (when the
3658 // region is freed) so they are ready when the region is
3659 // re-allocated. The only exception to this is if there's an
3660 // evacuation failure and instead of freeing the region we leave
3661 // it in the heap. In that case, we reset these fields during
3662 // evacuation failure handling.
3663 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3664
3665 // Here's a good place to add any other checks we'd like to
3666 // perform on CSet regions.
3667 return false;
3668 }
3669 };
3670 #endif // ASSERT
3671
3672 #if TASKQUEUE_STATS
3673 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3674 st->print_raw_cr("GC Task Stats");
3675 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3676 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3677 }
3678
3679 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3680 print_taskqueue_stats_hdr(st);
3681
3682 TaskQueueStats totals;
3683 const int n = workers() != NULL ? workers()->total_workers() : 1;
3684 for (int i = 0; i < n; ++i) {
3685 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3686 totals += task_queue(i)->stats;
3687 }
3688 st->print_raw("tot "); totals.print(st); st->cr();
3689
3690 DEBUG_ONLY(totals.verify());
3691 }
3692
3693 void G1CollectedHeap::reset_taskqueue_stats() {
3694 const int n = workers() != NULL ? workers()->total_workers() : 1;
3695 for (int i = 0; i < n; ++i) {
3696 task_queue(i)->stats.reset();
3697 }
3698 }
3699 #endif // TASKQUEUE_STATS
3700
3701 void G1CollectedHeap::log_gc_header() {
3702 if (!G1Log::fine()) {
3703 return;
3704 }
3705
3706 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3707
3708 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3709 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3710 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3711
3712 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3713 }
3714
3715 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3716 if (!G1Log::fine()) {
3717 return;
3718 }
3719
3720 if (G1Log::finer()) {
3721 if (evacuation_failed()) {
3722 gclog_or_tty->print(" (to-space exhausted)");
3723 }
3724 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3725 g1_policy()->phase_times()->note_gc_end();
3726 g1_policy()->phase_times()->print(pause_time_sec);
3727 g1_policy()->print_detailed_heap_transition();
3728 } else {
3729 if (evacuation_failed()) {
3730 gclog_or_tty->print("--");
3731 }
3732 g1_policy()->print_heap_transition();
3733 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3734 }
3735 gclog_or_tty->flush();
3736 }
3737
3738 bool
3739 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3740 assert_at_safepoint(true /* should_be_vm_thread */);
3741 guarantee(!is_gc_active(), "collection is not reentrant");
3742
3743 if (GC_locker::check_active_before_gc()) {
3744 return false;
3745 }
3746
3747 _gc_timer_stw->register_gc_start();
3748
3749 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3750
3751 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3752 ResourceMark rm;
3753
3754 print_heap_before_gc();
3755 trace_heap_before_gc(_gc_tracer_stw);
3756
3757 verify_region_sets_optional();
3758 verify_dirty_young_regions();
3759
3760 // This call will decide whether this pause is an initial-mark
3761 // pause. If it is, during_initial_mark_pause() will return true
3762 // for the duration of this pause.
3763 g1_policy()->decide_on_conc_mark_initiation();
3764
3765 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3766 assert(!g1_policy()->during_initial_mark_pause() ||
3767 g1_policy()->gcs_are_young(), "sanity");
3768
3769 // We also do not allow mixed GCs during marking.
3770 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3771
3772 // Record whether this pause is an initial mark. When the current
3773 // thread has completed its logging output and it's safe to signal
3774 // the CM thread, the flag's value in the policy has been reset.
3775 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3776
3777 // Inner scope for scope based logging, timers, and stats collection
3778 {
3779 EvacuationInfo evacuation_info;
3780
3781 if (g1_policy()->during_initial_mark_pause()) {
3782 // We are about to start a marking cycle, so we increment the
3783 // full collection counter.
3784 increment_old_marking_cycles_started();
3785 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3786 }
3787
3788 _gc_tracer_stw->report_yc_type(yc_type());
3789
3790 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3791
3792 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3793 workers()->active_workers() : 1);
3794 double pause_start_sec = os::elapsedTime();
3795 g1_policy()->phase_times()->note_gc_start(active_workers);
3796 log_gc_header();
3797
3798 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3799 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3800
3801 // If the secondary_free_list is not empty, append it to the
3802 // free_list. No need to wait for the cleanup operation to finish;
3803 // the region allocation code will check the secondary_free_list
3804 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3805 // set, skip this step so that the region allocation code has to
3806 // get entries from the secondary_free_list.
3807 if (!G1StressConcRegionFreeing) {
3808 append_secondary_free_list_if_not_empty_with_lock();
3809 }
3810
3811 assert(check_young_list_well_formed(), "young list should be well formed");
3812
3813 // Don't dynamically change the number of GC threads this early. A value of
3814 // 0 is used to indicate serial work. When parallel work is done,
3815 // it will be set.
3816
3817 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3818 IsGCActiveMark x;
3819
3820 gc_prologue(false);
3821 increment_total_collections(false /* full gc */);
3822 increment_gc_time_stamp();
3823
3824 verify_before_gc();
3825
3826 check_bitmaps("GC Start");
3827
3828 COMPILER2_PRESENT(DerivedPointerTable::clear());
3829
3830 // Please see comment in g1CollectedHeap.hpp and
3831 // G1CollectedHeap::ref_processing_init() to see how
3832 // reference processing currently works in G1.
3833
3834 // Enable discovery in the STW reference processor
3835 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3836 true /*verify_no_refs*/);
3837
3838 {
3839 // We want to temporarily turn off discovery by the
3840 // CM ref processor, if necessary, and turn it back on
3841 // on again later if we do. Using a scoped
3842 // NoRefDiscovery object will do this.
3843 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3844
3845 // Forget the current alloc region (we might even choose it to be part
3846 // of the collection set!).
3847 _allocator->release_mutator_alloc_region();
3848
3849 // We should call this after we retire the mutator alloc
3850 // region(s) so that all the ALLOC / RETIRE events are generated
3851 // before the start GC event.
3852 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3853
3854 // This timing is only used by the ergonomics to handle our pause target.
3855 // It is unclear why this should not include the full pause. We will
3856 // investigate this in CR 7178365.
3857 //
3858 // Preserving the old comment here if that helps the investigation:
3859 //
3860 // The elapsed time induced by the start time below deliberately elides
3861 // the possible verification above.
3862 double sample_start_time_sec = os::elapsedTime();
3863
3864 #if YOUNG_LIST_VERBOSE
3865 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3866 _young_list->print();
3867 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3868 #endif // YOUNG_LIST_VERBOSE
3869
3870 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3871
3872 double scan_wait_start = os::elapsedTime();
3873 // We have to wait until the CM threads finish scanning the
3874 // root regions as it's the only way to ensure that all the
3875 // objects on them have been correctly scanned before we start
3876 // moving them during the GC.
3877 bool waited = _cm->root_regions()->wait_until_scan_finished();
3878 double wait_time_ms = 0.0;
3879 if (waited) {
3880 double scan_wait_end = os::elapsedTime();
3881 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3882 }
3883 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3884
3885 #if YOUNG_LIST_VERBOSE
3886 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3887 _young_list->print();
3888 #endif // YOUNG_LIST_VERBOSE
3889
3890 if (g1_policy()->during_initial_mark_pause()) {
3891 concurrent_mark()->checkpointRootsInitialPre();
3892 }
3893
3894 #if YOUNG_LIST_VERBOSE
3895 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3896 _young_list->print();
3897 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3898 #endif // YOUNG_LIST_VERBOSE
3899
3900 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3901
3902 register_humongous_regions_with_in_cset_fast_test();
3903
3904 _cm->note_start_of_gc();
3905 // We should not verify the per-thread SATB buffers given that
3906 // we have not filtered them yet (we'll do so during the
3907 // GC). We also call this after finalize_cset() to
3908 // ensure that the CSet has been finalized.
3909 _cm->verify_no_cset_oops(true /* verify_stacks */,
3910 true /* verify_enqueued_buffers */,
3911 false /* verify_thread_buffers */,
3912 true /* verify_fingers */);
3913
3914 if (_hr_printer.is_active()) {
3915 HeapRegion* hr = g1_policy()->collection_set();
3916 while (hr != NULL) {
3917 _hr_printer.cset(hr);
3918 hr = hr->next_in_collection_set();
3919 }
3920 }
3921
3922 #ifdef ASSERT
3923 VerifyCSetClosure cl;
3924 collection_set_iterate(&cl);
3925 #endif // ASSERT
3926
3927 setup_surviving_young_words();
3928
3929 // Initialize the GC alloc regions.
3930 _allocator->init_gc_alloc_regions(evacuation_info);
3931
3932 // Actually do the work...
3933 evacuate_collection_set(evacuation_info);
3934
3935 // We do this to mainly verify the per-thread SATB buffers
3936 // (which have been filtered by now) since we didn't verify
3937 // them earlier. No point in re-checking the stacks / enqueued
3938 // buffers given that the CSet has not changed since last time
3939 // we checked.
3940 _cm->verify_no_cset_oops(false /* verify_stacks */,
3941 false /* verify_enqueued_buffers */,
3942 true /* verify_thread_buffers */,
3943 true /* verify_fingers */);
3944
3945 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3946
3947 eagerly_reclaim_humongous_regions();
3948
3949 g1_policy()->clear_collection_set();
3950
3951 cleanup_surviving_young_words();
3952
3953 // Start a new incremental collection set for the next pause.
3954 g1_policy()->start_incremental_cset_building();
3955
3956 clear_cset_fast_test();
3957
3958 _young_list->reset_sampled_info();
3959
3960 // Don't check the whole heap at this point as the
3961 // GC alloc regions from this pause have been tagged
3962 // as survivors and moved on to the survivor list.
3963 // Survivor regions will fail the !is_young() check.
3964 assert(check_young_list_empty(false /* check_heap */),
3965 "young list should be empty");
3966
3967 #if YOUNG_LIST_VERBOSE
3968 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3969 _young_list->print();
3970 #endif // YOUNG_LIST_VERBOSE
3971
3972 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3973 _young_list->first_survivor_region(),
3974 _young_list->last_survivor_region());
3975
3976 _young_list->reset_auxilary_lists();
3977
3978 if (evacuation_failed()) {
3979 _allocator->set_used(recalculate_used());
3980 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3981 for (uint i = 0; i < n_queues; i++) {
3982 if (_evacuation_failed_info_array[i].has_failed()) {
3983 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3984 }
3985 }
3986 } else {
3987 // The "used" of the the collection set have already been subtracted
3988 // when they were freed. Add in the bytes evacuated.
3989 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3990 }
3991
3992 if (g1_policy()->during_initial_mark_pause()) {
3993 // We have to do this before we notify the CM threads that
3994 // they can start working to make sure that all the
3995 // appropriate initialization is done on the CM object.
3996 concurrent_mark()->checkpointRootsInitialPost();
3997 set_marking_started();
3998 // Note that we don't actually trigger the CM thread at
3999 // this point. We do that later when we're sure that
4000 // the current thread has completed its logging output.
4001 }
4002
4003 allocate_dummy_regions();
4004
4005 #if YOUNG_LIST_VERBOSE
4006 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4007 _young_list->print();
4008 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4009 #endif // YOUNG_LIST_VERBOSE
4010
4011 _allocator->init_mutator_alloc_region();
4012
4013 {
4014 size_t expand_bytes = g1_policy()->expansion_amount();
4015 if (expand_bytes > 0) {
4016 size_t bytes_before = capacity();
4017 // No need for an ergo verbose message here,
4018 // expansion_amount() does this when it returns a value > 0.
4019 if (!expand(expand_bytes)) {
4020 // We failed to expand the heap. Cannot do anything about it.
4021 }
4022 }
4023 }
4024
4025 // We redo the verification but now wrt to the new CSet which
4026 // has just got initialized after the previous CSet was freed.
4027 _cm->verify_no_cset_oops(true /* verify_stacks */,
4028 true /* verify_enqueued_buffers */,
4029 true /* verify_thread_buffers */,
4030 true /* verify_fingers */);
4031 _cm->note_end_of_gc();
4032
4033 // This timing is only used by the ergonomics to handle our pause target.
4034 // It is unclear why this should not include the full pause. We will
4035 // investigate this in CR 7178365.
4036 double sample_end_time_sec = os::elapsedTime();
4037 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4038 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4039
4040 MemoryService::track_memory_usage();
4041
4042 // In prepare_for_verify() below we'll need to scan the deferred
4043 // update buffers to bring the RSets up-to-date if
4044 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4045 // the update buffers we'll probably need to scan cards on the
4046 // regions we just allocated to (i.e., the GC alloc
4047 // regions). However, during the last GC we called
4048 // set_saved_mark() on all the GC alloc regions, so card
4049 // scanning might skip the [saved_mark_word()...top()] area of
4050 // those regions (i.e., the area we allocated objects into
4051 // during the last GC). But it shouldn't. Given that
4052 // saved_mark_word() is conditional on whether the GC time stamp
4053 // on the region is current or not, by incrementing the GC time
4054 // stamp here we invalidate all the GC time stamps on all the
4055 // regions and saved_mark_word() will simply return top() for
4056 // all the regions. This is a nicer way of ensuring this rather
4057 // than iterating over the regions and fixing them. In fact, the
4058 // GC time stamp increment here also ensures that
4059 // saved_mark_word() will return top() between pauses, i.e.,
4060 // during concurrent refinement. So we don't need the
4061 // is_gc_active() check to decided which top to use when
4062 // scanning cards (see CR 7039627).
4063 increment_gc_time_stamp();
4064
4065 verify_after_gc();
4066 check_bitmaps("GC End");
4067
4068 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4069 ref_processor_stw()->verify_no_references_recorded();
4070
4071 // CM reference discovery will be re-enabled if necessary.
4072 }
4073
4074 // We should do this after we potentially expand the heap so
4075 // that all the COMMIT events are generated before the end GC
4076 // event, and after we retire the GC alloc regions so that all
4077 // RETIRE events are generated before the end GC event.
4078 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4079
4080 #ifdef TRACESPINNING
4081 ParallelTaskTerminator::print_termination_counts();
4082 #endif
4083
4084 gc_epilogue(false);
4085 }
4086
4087 // Print the remainder of the GC log output.
4088 log_gc_footer(os::elapsedTime() - pause_start_sec);
4089
4090 // It is not yet to safe to tell the concurrent mark to
4091 // start as we have some optional output below. We don't want the
4092 // output from the concurrent mark thread interfering with this
4093 // logging output either.
4094
4095 _hrm.verify_optional();
4096 verify_region_sets_optional();
4097
4098 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4099 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4100
4101 print_heap_after_gc();
4102 trace_heap_after_gc(_gc_tracer_stw);
4103
4104 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4105 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4106 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4107 // before any GC notifications are raised.
4108 g1mm()->update_sizes();
4109
4110 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4111 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4112 _gc_timer_stw->register_gc_end();
4113 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4114 }
4115 // It should now be safe to tell the concurrent mark thread to start
4116 // without its logging output interfering with the logging output
4117 // that came from the pause.
4118
4119 if (should_start_conc_mark) {
4120 // CAUTION: after the doConcurrentMark() call below,
4121 // the concurrent marking thread(s) could be running
4122 // concurrently with us. Make sure that anything after
4123 // this point does not assume that we are the only GC thread
4124 // running. Note: of course, the actual marking work will
4125 // not start until the safepoint itself is released in
4126 // SuspendibleThreadSet::desynchronize().
4127 doConcurrentMark();
4128 }
4129
4130 return true;
4131 }
4132
4133 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4134 {
4135 size_t gclab_word_size;
4136 switch (purpose) {
4137 case GCAllocForSurvived:
4138 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4139 break;
4140 case GCAllocForTenured:
4141 gclab_word_size = _old_plab_stats.desired_plab_sz();
4142 break;
4143 default:
4144 assert(false, "unknown GCAllocPurpose");
4145 gclab_word_size = _old_plab_stats.desired_plab_sz();
4146 break;
4147 }
4148
4149 // Prevent humongous PLAB sizes for two reasons:
4150 // * PLABs are allocated using a similar paths as oops, but should
4151 // never be in a humongous region
4152 // * Allowing humongous PLABs needlessly churns the region free lists
4153 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4154 }
4155
4156 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4157 _drain_in_progress = false;
4158 set_evac_failure_closure(cl);
4159 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4160 }
4161
4162 void G1CollectedHeap::finalize_for_evac_failure() {
4163 assert(_evac_failure_scan_stack != NULL &&
4164 _evac_failure_scan_stack->length() == 0,
4165 "Postcondition");
4166 assert(!_drain_in_progress, "Postcondition");
4167 delete _evac_failure_scan_stack;
4168 _evac_failure_scan_stack = NULL;
4169 }
4170
4171 void G1CollectedHeap::remove_self_forwarding_pointers() {
4172 double remove_self_forwards_start = os::elapsedTime();
4173
4174 HeapRegionClaimer hrclaimer;
4175 G1ParRemoveSelfForwardPtrsTask rsfp_task(this, &hrclaimer);
4176
4177 if (G1CollectedHeap::use_parallel_gc_threads()) {
4178 set_par_threads();
4179 hrclaimer.initialize(workers()->active_workers());
4180 workers()->run_task(&rsfp_task);
4181 set_par_threads(0);
4182 } else {
4183 rsfp_task.work(0);
4184 }
4185
4186 // Now restore saved marks, if any.
4187 assert(_objs_with_preserved_marks.size() ==
4188 _preserved_marks_of_objs.size(), "Both or none.");
4189 while (!_objs_with_preserved_marks.is_empty()) {
4190 oop obj = _objs_with_preserved_marks.pop();
4191 markOop m = _preserved_marks_of_objs.pop();
4192 obj->set_mark(m);
4193 }
4194 _objs_with_preserved_marks.clear(true);
4195 _preserved_marks_of_objs.clear(true);
4196
4197 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4198 }
4199
4200 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4201 _evac_failure_scan_stack->push(obj);
4202 }
4203
4204 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4205 assert(_evac_failure_scan_stack != NULL, "precondition");
4206
4207 while (_evac_failure_scan_stack->length() > 0) {
4208 oop obj = _evac_failure_scan_stack->pop();
4209 _evac_failure_closure->set_region(heap_region_containing(obj));
4210 obj->oop_iterate_backwards(_evac_failure_closure);
4211 }
4212 }
4213
4214 oop
4215 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4216 oop old) {
4217 assert(obj_in_cs(old),
4218 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4219 (HeapWord*) old));
4220 markOop m = old->mark();
4221 oop forward_ptr = old->forward_to_atomic(old);
4222 if (forward_ptr == NULL) {
4223 // Forward-to-self succeeded.
4224 assert(_par_scan_state != NULL, "par scan state");
4225 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4226 uint queue_num = _par_scan_state->queue_num();
4227
4228 _evacuation_failed = true;
4229 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4230 if (_evac_failure_closure != cl) {
4231 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4232 assert(!_drain_in_progress,
4233 "Should only be true while someone holds the lock.");
4234 // Set the global evac-failure closure to the current thread's.
4235 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4236 set_evac_failure_closure(cl);
4237 // Now do the common part.
4238 handle_evacuation_failure_common(old, m);
4239 // Reset to NULL.
4240 set_evac_failure_closure(NULL);
4241 } else {
4242 // The lock is already held, and this is recursive.
4243 assert(_drain_in_progress, "This should only be the recursive case.");
4244 handle_evacuation_failure_common(old, m);
4245 }
4246 return old;
4247 } else {
4248 // Forward-to-self failed. Either someone else managed to allocate
4249 // space for this object (old != forward_ptr) or they beat us in
4250 // self-forwarding it (old == forward_ptr).
4251 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4252 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4253 "should not be in the CSet",
4254 (HeapWord*) old, (HeapWord*) forward_ptr));
4255 return forward_ptr;
4256 }
4257 }
4258
4259 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4260 preserve_mark_if_necessary(old, m);
4261
4262 HeapRegion* r = heap_region_containing(old);
4263 if (!r->evacuation_failed()) {
4264 r->set_evacuation_failed(true);
4265 _hr_printer.evac_failure(r);
4266 }
4267
4268 push_on_evac_failure_scan_stack(old);
4269
4270 if (!_drain_in_progress) {
4271 // prevent recursion in copy_to_survivor_space()
4272 _drain_in_progress = true;
4273 drain_evac_failure_scan_stack();
4274 _drain_in_progress = false;
4275 }
4276 }
4277
4278 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4279 assert(evacuation_failed(), "Oversaving!");
4280 // We want to call the "for_promotion_failure" version only in the
4281 // case of a promotion failure.
4282 if (m->must_be_preserved_for_promotion_failure(obj)) {
4283 _objs_with_preserved_marks.push(obj);
4284 _preserved_marks_of_objs.push(m);
4285 }
4286 }
4287
4288 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4289 size_t word_size,
4290 AllocationContext_t context) {
4291 if (purpose == GCAllocForSurvived) {
4292 HeapWord* result = survivor_attempt_allocation(word_size, context);
4293 if (result != NULL) {
4294 return result;
4295 } else {
4296 // Let's try to allocate in the old gen in case we can fit the
4297 // object there.
4298 return old_attempt_allocation(word_size, context);
4299 }
4300 } else {
4301 assert(purpose == GCAllocForTenured, "sanity");
4302 HeapWord* result = old_attempt_allocation(word_size, context);
4303 if (result != NULL) {
4304 return result;
4305 } else {
4306 // Let's try to allocate in the survivors in case we can fit the
4307 // object there.
4308 return survivor_attempt_allocation(word_size, context);
4309 }
4310 }
4311
4312 ShouldNotReachHere();
4313 // Trying to keep some compilers happy.
4314 return NULL;
4315 }
4316
4317 void G1ParCopyHelper::mark_object(oop obj) {
4318 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4319
4320 // We know that the object is not moving so it's safe to read its size.
4321 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4322 }
4323
4324 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4325 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4326 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4327 assert(from_obj != to_obj, "should not be self-forwarded");
4328
4329 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4330 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4331
4332 // The object might be in the process of being copied by another
4333 // worker so we cannot trust that its to-space image is
4334 // well-formed. So we have to read its size from its from-space
4335 // image which we know should not be changing.
4336 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4337 }
4338
4339 template <class T>
4340 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4341 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4342 _scanned_klass->record_modified_oops();
4343 }
4344 }
4345
4346 template <G1Barrier barrier, G1Mark do_mark_object>
4347 template <class T>
4348 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4349 T heap_oop = oopDesc::load_heap_oop(p);
4350
4351 if (oopDesc::is_null(heap_oop)) {
4352 return;
4353 }
4354
4355 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4356
4357 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4358
4359 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4360
4361 if (state == G1CollectedHeap::InCSet) {
4362 oop forwardee;
4363 if (obj->is_forwarded()) {
4364 forwardee = obj->forwardee();
4365 } else {
4366 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4367 }
4368 assert(forwardee != NULL, "forwardee should not be NULL");
4369 oopDesc::encode_store_heap_oop(p, forwardee);
4370 if (do_mark_object != G1MarkNone && forwardee != obj) {
4371 // If the object is self-forwarded we don't need to explicitly
4372 // mark it, the evacuation failure protocol will do so.
4373 mark_forwarded_object(obj, forwardee);
4374 }
4375
4376 if (barrier == G1BarrierKlass) {
4377 do_klass_barrier(p, forwardee);
4378 }
4379 } else {
4380 if (state == G1CollectedHeap::IsHumongous) {
4381 _g1->set_humongous_is_live(obj);
4382 }
4383 // The object is not in collection set. If we're a root scanning
4384 // closure during an initial mark pause then attempt to mark the object.
4385 if (do_mark_object == G1MarkFromRoot) {
4386 mark_object(obj);
4387 }
4388 }
4389
4390 if (barrier == G1BarrierEvac) {
4391 _par_scan_state->update_rs(_from, p, _worker_id);
4392 }
4393 }
4394
4395 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4396 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4397
4398 class G1ParEvacuateFollowersClosure : public VoidClosure {
4399 protected:
4400 G1CollectedHeap* _g1h;
4401 G1ParScanThreadState* _par_scan_state;
4402 RefToScanQueueSet* _queues;
4403 ParallelTaskTerminator* _terminator;
4404
4405 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4406 RefToScanQueueSet* queues() { return _queues; }
4407 ParallelTaskTerminator* terminator() { return _terminator; }
4408
4409 public:
4410 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4411 G1ParScanThreadState* par_scan_state,
4412 RefToScanQueueSet* queues,
4413 ParallelTaskTerminator* terminator)
4414 : _g1h(g1h), _par_scan_state(par_scan_state),
4415 _queues(queues), _terminator(terminator) {}
4416
4417 void do_void();
4418
4419 private:
4420 inline bool offer_termination();
4421 };
4422
4423 bool G1ParEvacuateFollowersClosure::offer_termination() {
4424 G1ParScanThreadState* const pss = par_scan_state();
4425 pss->start_term_time();
4426 const bool res = terminator()->offer_termination();
4427 pss->end_term_time();
4428 return res;
4429 }
4430
4431 void G1ParEvacuateFollowersClosure::do_void() {
4432 G1ParScanThreadState* const pss = par_scan_state();
4433 pss->trim_queue();
4434 do {
4435 pss->steal_and_trim_queue(queues());
4436 } while (!offer_termination());
4437 }
4438
4439 class G1KlassScanClosure : public KlassClosure {
4440 G1ParCopyHelper* _closure;
4441 bool _process_only_dirty;
4442 int _count;
4443 public:
4444 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4445 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4446 void do_klass(Klass* klass) {
4447 // If the klass has not been dirtied we know that there's
4448 // no references into the young gen and we can skip it.
4449 if (!_process_only_dirty || klass->has_modified_oops()) {
4450 // Clean the klass since we're going to scavenge all the metadata.
4451 klass->clear_modified_oops();
4452
4453 // Tell the closure that this klass is the Klass to scavenge
4454 // and is the one to dirty if oops are left pointing into the young gen.
4455 _closure->set_scanned_klass(klass);
4456
4457 klass->oops_do(_closure);
4458
4459 _closure->set_scanned_klass(NULL);
4460 }
4461 _count++;
4462 }
4463 };
4464
4465 class G1CodeBlobClosure : public CodeBlobClosure {
4466 class HeapRegionGatheringOopClosure : public OopClosure {
4467 G1CollectedHeap* _g1h;
4468 OopClosure* _work;
4469 nmethod* _nm;
4470
4471 template <typename T>
4472 void do_oop_work(T* p) {
4473 _work->do_oop(p);
4474 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4475 if (!oopDesc::is_null(oop_or_narrowoop)) {
4476 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4477 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4478 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");
4479 hr->add_strong_code_root(_nm);
4480 }
4481 }
4482
4483 public:
4484 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4485
4486 void do_oop(oop* o) {
4487 do_oop_work(o);
4488 }
4489
4490 void do_oop(narrowOop* o) {
4491 do_oop_work(o);
4492 }
4493
4494 void set_nm(nmethod* nm) {
4495 _nm = nm;
4496 }
4497 };
4498
4499 HeapRegionGatheringOopClosure _oc;
4500 public:
4501 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4502
4503 void do_code_blob(CodeBlob* cb) {
4504 nmethod* nm = cb->as_nmethod_or_null();
4505 if (nm != NULL) {
4506 if (!nm->test_set_oops_do_mark()) {
4507 _oc.set_nm(nm);
4508 nm->oops_do(&_oc);
4509 nm->fix_oop_relocations();
4510 }
4511 }
4512 }
4513 };
4514
4515 class G1ParTask : public AbstractGangTask {
4516 protected:
4517 G1CollectedHeap* _g1h;
4518 RefToScanQueueSet *_queues;
4519 ParallelTaskTerminator _terminator;
4520 uint _n_workers;
4521
4522 Mutex _stats_lock;
4523 Mutex* stats_lock() { return &_stats_lock; }
4524
4525 public:
4526 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4527 : AbstractGangTask("G1 collection"),
4528 _g1h(g1h),
4529 _queues(task_queues),
4530 _terminator(0, _queues),
4531 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4532 {}
4533
4534 RefToScanQueueSet* queues() { return _queues; }
4535
4536 RefToScanQueue *work_queue(int i) {
4537 return queues()->queue(i);
4538 }
4539
4540 ParallelTaskTerminator* terminator() { return &_terminator; }
4541
4542 virtual void set_for_termination(int active_workers) {
4543 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4544 // in the young space (_par_seq_tasks) in the G1 heap
4545 // for SequentialSubTasksDone.
4546 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4547 // both of which need setting by set_n_termination().
4548 _g1h->SharedHeap::set_n_termination(active_workers);
4549 _g1h->set_n_termination(active_workers);
4550 terminator()->reset_for_reuse(active_workers);
4551 _n_workers = active_workers;
4552 }
4553
4554 // Helps out with CLD processing.
4555 //
4556 // During InitialMark we need to:
4557 // 1) Scavenge all CLDs for the young GC.
4558 // 2) Mark all objects directly reachable from strong CLDs.
4559 template <G1Mark do_mark_object>
4560 class G1CLDClosure : public CLDClosure {
4561 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4562 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4563 G1KlassScanClosure _klass_in_cld_closure;
4564 bool _claim;
4565
4566 public:
4567 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4568 bool only_young, bool claim)
4569 : _oop_closure(oop_closure),
4570 _oop_in_klass_closure(oop_closure->g1(),
4571 oop_closure->pss(),
4572 oop_closure->rp()),
4573 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4574 _claim(claim) {
4575
4576 }
4577
4578 void do_cld(ClassLoaderData* cld) {
4579 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4580 }
4581 };
4582
4583 void work(uint worker_id) {
4584 if (worker_id >= _n_workers) return; // no work needed this round
4585
4586 double start_time_ms = os::elapsedTime() * 1000.0;
4587 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4588
4589 {
4590 ResourceMark rm;
4591 HandleMark hm;
4592
4593 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4594
4595 G1ParScanThreadState pss(_g1h, worker_id, rp);
4596 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4597
4598 pss.set_evac_failure_closure(&evac_failure_cl);
4599
4600 bool only_young = _g1h->g1_policy()->gcs_are_young();
4601
4602 // Non-IM young GC.
4603 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4604 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4605 only_young, // Only process dirty klasses.
4606 false); // No need to claim CLDs.
4607 // IM young GC.
4608 // Strong roots closures.
4609 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4610 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4611 false, // Process all klasses.
4612 true); // Need to claim CLDs.
4613 // Weak roots closures.
4614 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4615 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4616 false, // Process all klasses.
4617 true); // Need to claim CLDs.
4618
4619 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4620 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4621 // IM Weak code roots are handled later.
4622
4623 OopClosure* strong_root_cl;
4624 OopClosure* weak_root_cl;
4625 CLDClosure* strong_cld_cl;
4626 CLDClosure* weak_cld_cl;
4627 CodeBlobClosure* strong_code_cl;
4628
4629 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4630 // We also need to mark copied objects.
4631 strong_root_cl = &scan_mark_root_cl;
4632 strong_cld_cl = &scan_mark_cld_cl;
4633 strong_code_cl = &scan_mark_code_cl;
4634 if (ClassUnloadingWithConcurrentMark) {
4635 weak_root_cl = &scan_mark_weak_root_cl;
4636 weak_cld_cl = &scan_mark_weak_cld_cl;
4637 } else {
4638 weak_root_cl = &scan_mark_root_cl;
4639 weak_cld_cl = &scan_mark_cld_cl;
4640 }
4641 } else {
4642 strong_root_cl = &scan_only_root_cl;
4643 weak_root_cl = &scan_only_root_cl;
4644 strong_cld_cl = &scan_only_cld_cl;
4645 weak_cld_cl = &scan_only_cld_cl;
4646 strong_code_cl = &scan_only_code_cl;
4647 }
4648
4649
4650 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4651
4652 pss.start_strong_roots();
4653 _g1h->g1_process_roots(strong_root_cl,
4654 weak_root_cl,
4655 &push_heap_rs_cl,
4656 strong_cld_cl,
4657 weak_cld_cl,
4658 strong_code_cl,
4659 worker_id);
4660
4661 pss.end_strong_roots();
4662
4663 {
4664 double start = os::elapsedTime();
4665 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4666 evac.do_void();
4667 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4668 double term_ms = pss.term_time()*1000.0;
4669 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4670 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4671 }
4672 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4673 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4674
4675 if (ParallelGCVerbose) {
4676 MutexLocker x(stats_lock());
4677 pss.print_termination_stats(worker_id);
4678 }
4679
4680 assert(pss.queue_is_empty(), "should be empty");
4681
4682 // Close the inner scope so that the ResourceMark and HandleMark
4683 // destructors are executed here and are included as part of the
4684 // "GC Worker Time".
4685 }
4686
4687 double end_time_ms = os::elapsedTime() * 1000.0;
4688 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4689 }
4690 };
4691
4692 // *** Common G1 Evacuation Stuff
4693
4694 // This method is run in a GC worker.
4695
4696 void
4697 G1CollectedHeap::
4698 g1_process_roots(OopClosure* scan_non_heap_roots,
4699 OopClosure* scan_non_heap_weak_roots,
4700 OopsInHeapRegionClosure* scan_rs,
4701 CLDClosure* scan_strong_clds,
4702 CLDClosure* scan_weak_clds,
4703 CodeBlobClosure* scan_strong_code,
4704 uint worker_i) {
4705
4706 // First scan the shared roots.
4707 double ext_roots_start = os::elapsedTime();
4708 double closure_app_time_sec = 0.0;
4709
4710 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4711 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4712
4713 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4714 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4715
4716 process_roots(false, // no scoping; this is parallel code
4717 SharedHeap::SO_None,
4718 &buf_scan_non_heap_roots,
4719 &buf_scan_non_heap_weak_roots,
4720 scan_strong_clds,
4721 // Unloading Initial Marks handle the weak CLDs separately.
4722 (trace_metadata ? NULL : scan_weak_clds),
4723 scan_strong_code);
4724
4725 // Now the CM ref_processor roots.
4726 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4727 // We need to treat the discovered reference lists of the
4728 // concurrent mark ref processor as roots and keep entries
4729 // (which are added by the marking threads) on them live
4730 // until they can be processed at the end of marking.
4731 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4732 }
4733
4734 if (trace_metadata) {
4735 // Barrier to make sure all workers passed
4736 // the strong CLD and strong nmethods phases.
4737 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4738
4739 // Now take the complement of the strong CLDs.
4740 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4741 }
4742
4743 // Finish up any enqueued closure apps (attributed as object copy time).
4744 buf_scan_non_heap_roots.done();
4745 buf_scan_non_heap_weak_roots.done();
4746
4747 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4748 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4749
4750 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4751
4752 double ext_root_time_ms =
4753 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4754
4755 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4756
4757 // During conc marking we have to filter the per-thread SATB buffers
4758 // to make sure we remove any oops into the CSet (which will show up
4759 // as implicitly live).
4760 double satb_filtering_ms = 0.0;
4761 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4762 if (mark_in_progress()) {
4763 double satb_filter_start = os::elapsedTime();
4764
4765 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4766
4767 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4768 }
4769 }
4770 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4771
4772 // Now scan the complement of the collection set.
4773 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4774
4775 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4776
4777 _process_strong_tasks->all_tasks_completed();
4778 }
4779
4780 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4781 private:
4782 BoolObjectClosure* _is_alive;
4783 int _initial_string_table_size;
4784 int _initial_symbol_table_size;
4785
4786 bool _process_strings;
4787 int _strings_processed;
4788 int _strings_removed;
4789
4790 bool _process_symbols;
4791 int _symbols_processed;
4792 int _symbols_removed;
4793
4794 bool _do_in_parallel;
4795 public:
4796 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4797 AbstractGangTask("String/Symbol Unlinking"),
4798 _is_alive(is_alive),
4799 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4800 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4801 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4802
4803 _initial_string_table_size = StringTable::the_table()->table_size();
4804 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4805 if (process_strings) {
4806 StringTable::clear_parallel_claimed_index();
4807 }
4808 if (process_symbols) {
4809 SymbolTable::clear_parallel_claimed_index();
4810 }
4811 }
4812
4813 ~G1StringSymbolTableUnlinkTask() {
4814 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4815 err_msg("claim value %d after unlink less than initial string table size %d",
4816 StringTable::parallel_claimed_index(), _initial_string_table_size));
4817 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4818 err_msg("claim value %d after unlink less than initial symbol table size %d",
4819 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4820
4821 if (G1TraceStringSymbolTableScrubbing) {
4822 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4823 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4824 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4825 strings_processed(), strings_removed(),
4826 symbols_processed(), symbols_removed());
4827 }
4828 }
4829
4830 void work(uint worker_id) {
4831 if (_do_in_parallel) {
4832 int strings_processed = 0;
4833 int strings_removed = 0;
4834 int symbols_processed = 0;
4835 int symbols_removed = 0;
4836 if (_process_strings) {
4837 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4838 Atomic::add(strings_processed, &_strings_processed);
4839 Atomic::add(strings_removed, &_strings_removed);
4840 }
4841 if (_process_symbols) {
4842 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4843 Atomic::add(symbols_processed, &_symbols_processed);
4844 Atomic::add(symbols_removed, &_symbols_removed);
4845 }
4846 } else {
4847 if (_process_strings) {
4848 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
4849 }
4850 if (_process_symbols) {
4851 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
4852 }
4853 }
4854 }
4855
4856 size_t strings_processed() const { return (size_t)_strings_processed; }
4857 size_t strings_removed() const { return (size_t)_strings_removed; }
4858
4859 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4860 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4861 };
4862
4863 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4864 private:
4865 static Monitor* _lock;
4866
4867 BoolObjectClosure* const _is_alive;
4868 const bool _unloading_occurred;
4869 const uint _num_workers;
4870
4871 // Variables used to claim nmethods.
4872 nmethod* _first_nmethod;
4873 volatile nmethod* _claimed_nmethod;
4874
4875 // The list of nmethods that need to be processed by the second pass.
4876 volatile nmethod* _postponed_list;
4877 volatile uint _num_entered_barrier;
4878
4879 public:
4880 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4881 _is_alive(is_alive),
4882 _unloading_occurred(unloading_occurred),
4883 _num_workers(num_workers),
4884 _first_nmethod(NULL),
4885 _claimed_nmethod(NULL),
4886 _postponed_list(NULL),
4887 _num_entered_barrier(0)
4888 {
4889 nmethod::increase_unloading_clock();
4890 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
4891 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4892 }
4893
4894 ~G1CodeCacheUnloadingTask() {
4895 CodeCache::verify_clean_inline_caches();
4896
4897 CodeCache::set_needs_cache_clean(false);
4898 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4899
4900 CodeCache::verify_icholder_relocations();
4901 }
4902
4903 private:
4904 void add_to_postponed_list(nmethod* nm) {
4905 nmethod* old;
4906 do {
4907 old = (nmethod*)_postponed_list;
4908 nm->set_unloading_next(old);
4909 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4910 }
4911
4912 void clean_nmethod(nmethod* nm) {
4913 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4914
4915 if (postponed) {
4916 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4917 add_to_postponed_list(nm);
4918 }
4919
4920 // Mark that this thread has been cleaned/unloaded.
4921 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4922 nm->set_unloading_clock(nmethod::global_unloading_clock());
4923 }
4924
4925 void clean_nmethod_postponed(nmethod* nm) {
4926 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4927 }
4928
4929 static const int MaxClaimNmethods = 16;
4930
4931 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4932 nmethod* first;
4933 nmethod* last;
4934
4935 do {
4936 *num_claimed_nmethods = 0;
4937
4938 first = last = (nmethod*)_claimed_nmethod;
4939
4940 if (first != NULL) {
4941 for (int i = 0; i < MaxClaimNmethods; i++) {
4942 last = CodeCache::alive_nmethod(CodeCache::next(last));
4943
4944 if (last == NULL) {
4945 break;
4946 }
4947
4948 claimed_nmethods[i] = last;
4949 (*num_claimed_nmethods)++;
4950 }
4951 }
4952
4953 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
4954 }
4955
4956 nmethod* claim_postponed_nmethod() {
4957 nmethod* claim;
4958 nmethod* next;
4959
4960 do {
4961 claim = (nmethod*)_postponed_list;
4962 if (claim == NULL) {
4963 return NULL;
4964 }
4965
4966 next = claim->unloading_next();
4967
4968 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4969
4970 return claim;
4971 }
4972
4973 public:
4974 // Mark that we're done with the first pass of nmethod cleaning.
4975 void barrier_mark(uint worker_id) {
4976 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4977 _num_entered_barrier++;
4978 if (_num_entered_barrier == _num_workers) {
4979 ml.notify_all();
4980 }
4981 }
4982
4983 // See if we have to wait for the other workers to
4984 // finish their first-pass nmethod cleaning work.
4985 void barrier_wait(uint worker_id) {
4986 if (_num_entered_barrier < _num_workers) {
4987 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4988 while (_num_entered_barrier < _num_workers) {
4989 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4990 }
4991 }
4992 }
4993
4994 // Cleaning and unloading of nmethods. Some work has to be postponed
4995 // to the second pass, when we know which nmethods survive.
4996 void work_first_pass(uint worker_id) {
4997 // The first nmethods is claimed by the first worker.
4998 if (worker_id == 0 && _first_nmethod != NULL) {
4999 clean_nmethod(_first_nmethod);
5000 _first_nmethod = NULL;
5001 }
5002
5003 int num_claimed_nmethods;
5004 nmethod* claimed_nmethods[MaxClaimNmethods];
5005
5006 while (true) {
5007 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5008
5009 if (num_claimed_nmethods == 0) {
5010 break;
5011 }
5012
5013 for (int i = 0; i < num_claimed_nmethods; i++) {
5014 clean_nmethod(claimed_nmethods[i]);
5015 }
5016 }
5017 }
5018
5019 void work_second_pass(uint worker_id) {
5020 nmethod* nm;
5021 // Take care of postponed nmethods.
5022 while ((nm = claim_postponed_nmethod()) != NULL) {
5023 clean_nmethod_postponed(nm);
5024 }
5025 }
5026 };
5027
5028 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5029
5030 class G1KlassCleaningTask : public StackObj {
5031 BoolObjectClosure* _is_alive;
5032 volatile jint _clean_klass_tree_claimed;
5033 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5034
5035 public:
5036 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5037 _is_alive(is_alive),
5038 _clean_klass_tree_claimed(0),
5039 _klass_iterator() {
5040 }
5041
5042 private:
5043 bool claim_clean_klass_tree_task() {
5044 if (_clean_klass_tree_claimed) {
5045 return false;
5046 }
5047
5048 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5049 }
5050
5051 InstanceKlass* claim_next_klass() {
5052 Klass* klass;
5053 do {
5054 klass =_klass_iterator.next_klass();
5055 } while (klass != NULL && !klass->oop_is_instance());
5056
5057 return (InstanceKlass*)klass;
5058 }
5059
5060 public:
5061
5062 void clean_klass(InstanceKlass* ik) {
5063 ik->clean_implementors_list(_is_alive);
5064 ik->clean_method_data(_is_alive);
5065
5066 // G1 specific cleanup work that has
5067 // been moved here to be done in parallel.
5068 ik->clean_dependent_nmethods();
5069 }
5070
5071 void work() {
5072 ResourceMark rm;
5073
5074 // One worker will clean the subklass/sibling klass tree.
5075 if (claim_clean_klass_tree_task()) {
5076 Klass::clean_subklass_tree(_is_alive);
5077 }
5078
5079 // All workers will help cleaning the classes,
5080 InstanceKlass* klass;
5081 while ((klass = claim_next_klass()) != NULL) {
5082 clean_klass(klass);
5083 }
5084 }
5085 };
5086
5087 // To minimize the remark pause times, the tasks below are done in parallel.
5088 class G1ParallelCleaningTask : public AbstractGangTask {
5089 private:
5090 G1StringSymbolTableUnlinkTask _string_symbol_task;
5091 G1CodeCacheUnloadingTask _code_cache_task;
5092 G1KlassCleaningTask _klass_cleaning_task;
5093
5094 public:
5095 // The constructor is run in the VMThread.
5096 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5097 AbstractGangTask("Parallel Cleaning"),
5098 _string_symbol_task(is_alive, process_strings, process_symbols),
5099 _code_cache_task(num_workers, is_alive, unloading_occurred),
5100 _klass_cleaning_task(is_alive) {
5101 }
5102
5103 // The parallel work done by all worker threads.
5104 void work(uint worker_id) {
5105 // Do first pass of code cache cleaning.
5106 _code_cache_task.work_first_pass(worker_id);
5107
5108 // Let the threads mark that the first pass is done.
5109 _code_cache_task.barrier_mark(worker_id);
5110
5111 // Clean the Strings and Symbols.
5112 _string_symbol_task.work(worker_id);
5113
5114 // Wait for all workers to finish the first code cache cleaning pass.
5115 _code_cache_task.barrier_wait(worker_id);
5116
5117 // Do the second code cache cleaning work, which realize on
5118 // the liveness information gathered during the first pass.
5119 _code_cache_task.work_second_pass(worker_id);
5120
5121 // Clean all klasses that were not unloaded.
5122 _klass_cleaning_task.work();
5123 }
5124 };
5125
5126
5127 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5128 bool process_strings,
5129 bool process_symbols,
5130 bool class_unloading_occurred) {
5131 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5132 workers()->active_workers() : 1);
5133
5134 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5135 n_workers, class_unloading_occurred);
5136 if (G1CollectedHeap::use_parallel_gc_threads()) {
5137 set_par_threads(n_workers);
5138 workers()->run_task(&g1_unlink_task);
5139 set_par_threads(0);
5140 } else {
5141 g1_unlink_task.work(0);
5142 }
5143 }
5144
5145 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5146 bool process_strings, bool process_symbols) {
5147 {
5148 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5149 _g1h->workers()->active_workers() : 1);
5150 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5151 if (G1CollectedHeap::use_parallel_gc_threads()) {
5152 set_par_threads(n_workers);
5153 workers()->run_task(&g1_unlink_task);
5154 set_par_threads(0);
5155 } else {
5156 g1_unlink_task.work(0);
5157 }
5158 }
5159
5160 if (G1StringDedup::is_enabled()) {
5161 G1StringDedup::unlink(is_alive);
5162 }
5163 }
5164
5165 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5166 private:
5167 DirtyCardQueueSet* _queue;
5168 public:
5169 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5170
5171 virtual void work(uint worker_id) {
5172 double start_time = os::elapsedTime();
5173
5174 RedirtyLoggedCardTableEntryClosure cl;
5175 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5176 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5177 } else {
5178 _queue->apply_closure_to_all_completed_buffers(&cl);
5179 }
5180
5181 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5182 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5183 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5184 }
5185 };
5186
5187 void G1CollectedHeap::redirty_logged_cards() {
5188 double redirty_logged_cards_start = os::elapsedTime();
5189
5190 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5191 _g1h->workers()->active_workers() : 1);
5192
5193 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5194 dirty_card_queue_set().reset_for_par_iteration();
5195 if (use_parallel_gc_threads()) {
5196 set_par_threads(n_workers);
5197 workers()->run_task(&redirty_task);
5198 set_par_threads(0);
5199 } else {
5200 redirty_task.work(0);
5201 }
5202
5203 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5204 dcq.merge_bufferlists(&dirty_card_queue_set());
5205 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5206
5207 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5208 }
5209
5210 // Weak Reference Processing support
5211
5212 // An always "is_alive" closure that is used to preserve referents.
5213 // If the object is non-null then it's alive. Used in the preservation
5214 // of referent objects that are pointed to by reference objects
5215 // discovered by the CM ref processor.
5216 class G1AlwaysAliveClosure: public BoolObjectClosure {
5217 G1CollectedHeap* _g1;
5218 public:
5219 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5220 bool do_object_b(oop p) {
5221 if (p != NULL) {
5222 return true;
5223 }
5224 return false;
5225 }
5226 };
5227
5228 bool G1STWIsAliveClosure::do_object_b(oop p) {
5229 // An object is reachable if it is outside the collection set,
5230 // or is inside and copied.
5231 return !_g1->obj_in_cs(p) || p->is_forwarded();
5232 }
5233
5234 // Non Copying Keep Alive closure
5235 class G1KeepAliveClosure: public OopClosure {
5236 G1CollectedHeap* _g1;
5237 public:
5238 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5239 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5240 void do_oop(oop* p) {
5241 oop obj = *p;
5242 assert(obj != NULL, "the caller should have filtered out NULL values");
5243
5244 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5245 if (cset_state == G1CollectedHeap::InNeither) {
5246 return;
5247 }
5248 if (cset_state == G1CollectedHeap::InCSet) {
5249 assert( obj->is_forwarded(), "invariant" );
5250 *p = obj->forwardee();
5251 } else {
5252 assert(!obj->is_forwarded(), "invariant" );
5253 assert(cset_state == G1CollectedHeap::IsHumongous,
5254 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5255 _g1->set_humongous_is_live(obj);
5256 }
5257 }
5258 };
5259
5260 // Copying Keep Alive closure - can be called from both
5261 // serial and parallel code as long as different worker
5262 // threads utilize different G1ParScanThreadState instances
5263 // and different queues.
5264
5265 class G1CopyingKeepAliveClosure: public OopClosure {
5266 G1CollectedHeap* _g1h;
5267 OopClosure* _copy_non_heap_obj_cl;
5268 G1ParScanThreadState* _par_scan_state;
5269
5270 public:
5271 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5272 OopClosure* non_heap_obj_cl,
5273 G1ParScanThreadState* pss):
5274 _g1h(g1h),
5275 _copy_non_heap_obj_cl(non_heap_obj_cl),
5276 _par_scan_state(pss)
5277 {}
5278
5279 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5280 virtual void do_oop( oop* p) { do_oop_work(p); }
5281
5282 template <class T> void do_oop_work(T* p) {
5283 oop obj = oopDesc::load_decode_heap_oop(p);
5284
5285 if (_g1h->is_in_cset_or_humongous(obj)) {
5286 // If the referent object has been forwarded (either copied
5287 // to a new location or to itself in the event of an
5288 // evacuation failure) then we need to update the reference
5289 // field and, if both reference and referent are in the G1
5290 // heap, update the RSet for the referent.
5291 //
5292 // If the referent has not been forwarded then we have to keep
5293 // it alive by policy. Therefore we have copy the referent.
5294 //
5295 // If the reference field is in the G1 heap then we can push
5296 // on the PSS queue. When the queue is drained (after each
5297 // phase of reference processing) the object and it's followers
5298 // will be copied, the reference field set to point to the
5299 // new location, and the RSet updated. Otherwise we need to
5300 // use the the non-heap or metadata closures directly to copy
5301 // the referent object and update the pointer, while avoiding
5302 // updating the RSet.
5303
5304 if (_g1h->is_in_g1_reserved(p)) {
5305 _par_scan_state->push_on_queue(p);
5306 } else {
5307 assert(!Metaspace::contains((const void*)p),
5308 err_msg("Unexpectedly found a pointer from metadata: "
5309 PTR_FORMAT, p));
5310 _copy_non_heap_obj_cl->do_oop(p);
5311 }
5312 }
5313 }
5314 };
5315
5316 // Serial drain queue closure. Called as the 'complete_gc'
5317 // closure for each discovered list in some of the
5318 // reference processing phases.
5319
5320 class G1STWDrainQueueClosure: public VoidClosure {
5321 protected:
5322 G1CollectedHeap* _g1h;
5323 G1ParScanThreadState* _par_scan_state;
5324
5325 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5326
5327 public:
5328 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5329 _g1h(g1h),
5330 _par_scan_state(pss)
5331 { }
5332
5333 void do_void() {
5334 G1ParScanThreadState* const pss = par_scan_state();
5335 pss->trim_queue();
5336 }
5337 };
5338
5339 // Parallel Reference Processing closures
5340
5341 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5342 // processing during G1 evacuation pauses.
5343
5344 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5345 private:
5346 G1CollectedHeap* _g1h;
5347 RefToScanQueueSet* _queues;
5348 FlexibleWorkGang* _workers;
5349 int _active_workers;
5350
5351 public:
5352 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5353 FlexibleWorkGang* workers,
5354 RefToScanQueueSet *task_queues,
5355 int n_workers) :
5356 _g1h(g1h),
5357 _queues(task_queues),
5358 _workers(workers),
5359 _active_workers(n_workers)
5360 {
5361 assert(n_workers > 0, "shouldn't call this otherwise");
5362 }
5363
5364 // Executes the given task using concurrent marking worker threads.
5365 virtual void execute(ProcessTask& task);
5366 virtual void execute(EnqueueTask& task);
5367 };
5368
5369 // Gang task for possibly parallel reference processing
5370
5371 class G1STWRefProcTaskProxy: public AbstractGangTask {
5372 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5373 ProcessTask& _proc_task;
5374 G1CollectedHeap* _g1h;
5375 RefToScanQueueSet *_task_queues;
5376 ParallelTaskTerminator* _terminator;
5377
5378 public:
5379 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5380 G1CollectedHeap* g1h,
5381 RefToScanQueueSet *task_queues,
5382 ParallelTaskTerminator* terminator) :
5383 AbstractGangTask("Process reference objects in parallel"),
5384 _proc_task(proc_task),
5385 _g1h(g1h),
5386 _task_queues(task_queues),
5387 _terminator(terminator)
5388 {}
5389
5390 virtual void work(uint worker_id) {
5391 // The reference processing task executed by a single worker.
5392 ResourceMark rm;
5393 HandleMark hm;
5394
5395 G1STWIsAliveClosure is_alive(_g1h);
5396
5397 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5398 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5399
5400 pss.set_evac_failure_closure(&evac_failure_cl);
5401
5402 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5403
5404 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5405
5406 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5407
5408 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5409 // We also need to mark copied objects.
5410 copy_non_heap_cl = ©_mark_non_heap_cl;
5411 }
5412
5413 // Keep alive closure.
5414 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5415
5416 // Complete GC closure
5417 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5418
5419 // Call the reference processing task's work routine.
5420 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5421
5422 // Note we cannot assert that the refs array is empty here as not all
5423 // of the processing tasks (specifically phase2 - pp2_work) execute
5424 // the complete_gc closure (which ordinarily would drain the queue) so
5425 // the queue may not be empty.
5426 }
5427 };
5428
5429 // Driver routine for parallel reference processing.
5430 // Creates an instance of the ref processing gang
5431 // task and has the worker threads execute it.
5432 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5433 assert(_workers != NULL, "Need parallel worker threads.");
5434
5435 ParallelTaskTerminator terminator(_active_workers, _queues);
5436 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5437
5438 _g1h->set_par_threads(_active_workers);
5439 _workers->run_task(&proc_task_proxy);
5440 _g1h->set_par_threads(0);
5441 }
5442
5443 // Gang task for parallel reference enqueueing.
5444
5445 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5446 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5447 EnqueueTask& _enq_task;
5448
5449 public:
5450 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5451 AbstractGangTask("Enqueue reference objects in parallel"),
5452 _enq_task(enq_task)
5453 { }
5454
5455 virtual void work(uint worker_id) {
5456 _enq_task.work(worker_id);
5457 }
5458 };
5459
5460 // Driver routine for parallel reference enqueueing.
5461 // Creates an instance of the ref enqueueing gang
5462 // task and has the worker threads execute it.
5463
5464 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5465 assert(_workers != NULL, "Need parallel worker threads.");
5466
5467 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5468
5469 _g1h->set_par_threads(_active_workers);
5470 _workers->run_task(&enq_task_proxy);
5471 _g1h->set_par_threads(0);
5472 }
5473
5474 // End of weak reference support closures
5475
5476 // Abstract task used to preserve (i.e. copy) any referent objects
5477 // that are in the collection set and are pointed to by reference
5478 // objects discovered by the CM ref processor.
5479
5480 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5481 protected:
5482 G1CollectedHeap* _g1h;
5483 RefToScanQueueSet *_queues;
5484 ParallelTaskTerminator _terminator;
5485 uint _n_workers;
5486
5487 public:
5488 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5489 AbstractGangTask("ParPreserveCMReferents"),
5490 _g1h(g1h),
5491 _queues(task_queues),
5492 _terminator(workers, _queues),
5493 _n_workers(workers)
5494 { }
5495
5496 void work(uint worker_id) {
5497 ResourceMark rm;
5498 HandleMark hm;
5499
5500 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5501 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5502
5503 pss.set_evac_failure_closure(&evac_failure_cl);
5504
5505 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5506
5507 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5508
5509 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5510
5511 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5512
5513 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5514 // We also need to mark copied objects.
5515 copy_non_heap_cl = ©_mark_non_heap_cl;
5516 }
5517
5518 // Is alive closure
5519 G1AlwaysAliveClosure always_alive(_g1h);
5520
5521 // Copying keep alive closure. Applied to referent objects that need
5522 // to be copied.
5523 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5524
5525 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5526
5527 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5528 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5529
5530 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5531 // So this must be true - but assert just in case someone decides to
5532 // change the worker ids.
5533 assert(0 <= worker_id && worker_id < limit, "sanity");
5534 assert(!rp->discovery_is_atomic(), "check this code");
5535
5536 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5537 for (uint idx = worker_id; idx < limit; idx += stride) {
5538 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5539
5540 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5541 while (iter.has_next()) {
5542 // Since discovery is not atomic for the CM ref processor, we
5543 // can see some null referent objects.
5544 iter.load_ptrs(DEBUG_ONLY(true));
5545 oop ref = iter.obj();
5546
5547 // This will filter nulls.
5548 if (iter.is_referent_alive()) {
5549 iter.make_referent_alive();
5550 }
5551 iter.move_to_next();
5552 }
5553 }
5554
5555 // Drain the queue - which may cause stealing
5556 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5557 drain_queue.do_void();
5558 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5559 assert(pss.queue_is_empty(), "should be");
5560 }
5561 };
5562
5563 // Weak Reference processing during an evacuation pause (part 1).
5564 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5565 double ref_proc_start = os::elapsedTime();
5566
5567 ReferenceProcessor* rp = _ref_processor_stw;
5568 assert(rp->discovery_enabled(), "should have been enabled");
5569
5570 // Any reference objects, in the collection set, that were 'discovered'
5571 // by the CM ref processor should have already been copied (either by
5572 // applying the external root copy closure to the discovered lists, or
5573 // by following an RSet entry).
5574 //
5575 // But some of the referents, that are in the collection set, that these
5576 // reference objects point to may not have been copied: the STW ref
5577 // processor would have seen that the reference object had already
5578 // been 'discovered' and would have skipped discovering the reference,
5579 // but would not have treated the reference object as a regular oop.
5580 // As a result the copy closure would not have been applied to the
5581 // referent object.
5582 //
5583 // We need to explicitly copy these referent objects - the references
5584 // will be processed at the end of remarking.
5585 //
5586 // We also need to do this copying before we process the reference
5587 // objects discovered by the STW ref processor in case one of these
5588 // referents points to another object which is also referenced by an
5589 // object discovered by the STW ref processor.
5590
5591 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5592 no_of_gc_workers == workers()->active_workers(),
5593 "Need to reset active GC workers");
5594
5595 set_par_threads(no_of_gc_workers);
5596 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5597 no_of_gc_workers,
5598 _task_queues);
5599
5600 if (G1CollectedHeap::use_parallel_gc_threads()) {
5601 workers()->run_task(&keep_cm_referents);
5602 } else {
5603 keep_cm_referents.work(0);
5604 }
5605
5606 set_par_threads(0);
5607
5608 // Closure to test whether a referent is alive.
5609 G1STWIsAliveClosure is_alive(this);
5610
5611 // Even when parallel reference processing is enabled, the processing
5612 // of JNI refs is serial and performed serially by the current thread
5613 // rather than by a worker. The following PSS will be used for processing
5614 // JNI refs.
5615
5616 // Use only a single queue for this PSS.
5617 G1ParScanThreadState pss(this, 0, NULL);
5618
5619 // We do not embed a reference processor in the copying/scanning
5620 // closures while we're actually processing the discovered
5621 // reference objects.
5622 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5623
5624 pss.set_evac_failure_closure(&evac_failure_cl);
5625
5626 assert(pss.queue_is_empty(), "pre-condition");
5627
5628 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5629
5630 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5631
5632 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5633
5634 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5635 // We also need to mark copied objects.
5636 copy_non_heap_cl = ©_mark_non_heap_cl;
5637 }
5638
5639 // Keep alive closure.
5640 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5641
5642 // Serial Complete GC closure
5643 G1STWDrainQueueClosure drain_queue(this, &pss);
5644
5645 // Setup the soft refs policy...
5646 rp->setup_policy(false);
5647
5648 ReferenceProcessorStats stats;
5649 if (!rp->processing_is_mt()) {
5650 // Serial reference processing...
5651 stats = rp->process_discovered_references(&is_alive,
5652 &keep_alive,
5653 &drain_queue,
5654 NULL,
5655 _gc_timer_stw,
5656 _gc_tracer_stw->gc_id());
5657 } else {
5658 // Parallel reference processing
5659 assert(rp->num_q() == no_of_gc_workers, "sanity");
5660 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5661
5662 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5663 stats = rp->process_discovered_references(&is_alive,
5664 &keep_alive,
5665 &drain_queue,
5666 &par_task_executor,
5667 _gc_timer_stw,
5668 _gc_tracer_stw->gc_id());
5669 }
5670
5671 _gc_tracer_stw->report_gc_reference_stats(stats);
5672
5673 // We have completed copying any necessary live referent objects.
5674 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5675
5676 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5677 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5678 }
5679
5680 // Weak Reference processing during an evacuation pause (part 2).
5681 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5682 double ref_enq_start = os::elapsedTime();
5683
5684 ReferenceProcessor* rp = _ref_processor_stw;
5685 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5686
5687 // Now enqueue any remaining on the discovered lists on to
5688 // the pending list.
5689 if (!rp->processing_is_mt()) {
5690 // Serial reference processing...
5691 rp->enqueue_discovered_references();
5692 } else {
5693 // Parallel reference enqueueing
5694
5695 assert(no_of_gc_workers == workers()->active_workers(),
5696 "Need to reset active workers");
5697 assert(rp->num_q() == no_of_gc_workers, "sanity");
5698 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5699
5700 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5701 rp->enqueue_discovered_references(&par_task_executor);
5702 }
5703
5704 rp->verify_no_references_recorded();
5705 assert(!rp->discovery_enabled(), "should have been disabled");
5706
5707 // FIXME
5708 // CM's reference processing also cleans up the string and symbol tables.
5709 // Should we do that here also? We could, but it is a serial operation
5710 // and could significantly increase the pause time.
5711
5712 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5713 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5714 }
5715
5716 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5717 _expand_heap_after_alloc_failure = true;
5718 _evacuation_failed = false;
5719
5720 // Should G1EvacuationFailureALot be in effect for this GC?
5721 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5722
5723 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5724
5725 // Disable the hot card cache.
5726 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5727 hot_card_cache->reset_hot_cache_claimed_index();
5728 hot_card_cache->set_use_cache(false);
5729
5730 uint n_workers;
5731 if (G1CollectedHeap::use_parallel_gc_threads()) {
5732 n_workers =
5733 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5734 workers()->active_workers(),
5735 Threads::number_of_non_daemon_threads());
5736 assert(UseDynamicNumberOfGCThreads ||
5737 n_workers == workers()->total_workers(),
5738 "If not dynamic should be using all the workers");
5739 workers()->set_active_workers(n_workers);
5740 set_par_threads(n_workers);
5741 } else {
5742 assert(n_par_threads() == 0,
5743 "Should be the original non-parallel value");
5744 n_workers = 1;
5745 }
5746
5747 G1ParTask g1_par_task(this, _task_queues);
5748
5749 init_for_evac_failure(NULL);
5750
5751 rem_set()->prepare_for_younger_refs_iterate(true);
5752
5753 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5754 double start_par_time_sec = os::elapsedTime();
5755 double end_par_time_sec;
5756
5757 {
5758 StrongRootsScope srs(this);
5759 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5760 if (g1_policy()->during_initial_mark_pause()) {
5761 ClassLoaderDataGraph::clear_claimed_marks();
5762 }
5763
5764 if (G1CollectedHeap::use_parallel_gc_threads()) {
5765 // The individual threads will set their evac-failure closures.
5766 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5767 // These tasks use ShareHeap::_process_strong_tasks
5768 assert(UseDynamicNumberOfGCThreads ||
5769 workers()->active_workers() == workers()->total_workers(),
5770 "If not dynamic should be using all the workers");
5771 workers()->run_task(&g1_par_task);
5772 } else {
5773 g1_par_task.set_for_termination(n_workers);
5774 g1_par_task.work(0);
5775 }
5776 end_par_time_sec = os::elapsedTime();
5777
5778 // Closing the inner scope will execute the destructor
5779 // for the StrongRootsScope object. We record the current
5780 // elapsed time before closing the scope so that time
5781 // taken for the SRS destructor is NOT included in the
5782 // reported parallel time.
5783 }
5784
5785 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5786 g1_policy()->phase_times()->record_par_time(par_time_ms);
5787
5788 double code_root_fixup_time_ms =
5789 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5790 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5791
5792 set_par_threads(0);
5793
5794 // Process any discovered reference objects - we have
5795 // to do this _before_ we retire the GC alloc regions
5796 // as we may have to copy some 'reachable' referent
5797 // objects (and their reachable sub-graphs) that were
5798 // not copied during the pause.
5799 process_discovered_references(n_workers);
5800
5801 // Weak root processing.
5802 {
5803 G1STWIsAliveClosure is_alive(this);
5804 G1KeepAliveClosure keep_alive(this);
5805 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5806 if (G1StringDedup::is_enabled()) {
5807 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5808 }
5809 }
5810
5811 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5812 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5813
5814 // Reset and re-enable the hot card cache.
5815 // Note the counts for the cards in the regions in the
5816 // collection set are reset when the collection set is freed.
5817 hot_card_cache->reset_hot_cache();
5818 hot_card_cache->set_use_cache(true);
5819
5820 purge_code_root_memory();
5821
5822 finalize_for_evac_failure();
5823
5824 if (evacuation_failed()) {
5825 remove_self_forwarding_pointers();
5826
5827 // Reset the G1EvacuationFailureALot counters and flags
5828 // Note: the values are reset only when an actual
5829 // evacuation failure occurs.
5830 NOT_PRODUCT(reset_evacuation_should_fail();)
5831 }
5832
5833 // Enqueue any remaining references remaining on the STW
5834 // reference processor's discovered lists. We need to do
5835 // this after the card table is cleaned (and verified) as
5836 // the act of enqueueing entries on to the pending list
5837 // will log these updates (and dirty their associated
5838 // cards). We need these updates logged to update any
5839 // RSets.
5840 enqueue_discovered_references(n_workers);
5841
5842 redirty_logged_cards();
5843 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5844 }
5845
5846 void G1CollectedHeap::free_region(HeapRegion* hr,
5847 FreeRegionList* free_list,
5848 bool par,
5849 bool locked) {
5850 assert(!hr->is_free(), "the region should not be free");
5851 assert(!hr->is_empty(), "the region should not be empty");
5852 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5853 assert(free_list != NULL, "pre-condition");
5854
5855 if (G1VerifyBitmaps) {
5856 MemRegion mr(hr->bottom(), hr->end());
5857 concurrent_mark()->clearRangePrevBitmap(mr);
5858 }
5859
5860 // Clear the card counts for this region.
5861 // Note: we only need to do this if the region is not young
5862 // (since we don't refine cards in young regions).
5863 if (!hr->is_young()) {
5864 _cg1r->hot_card_cache()->reset_card_counts(hr);
5865 }
5866 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5867 free_list->add_ordered(hr);
5868 }
5869
5870 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5871 FreeRegionList* free_list,
5872 bool par) {
5873 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5874 assert(free_list != NULL, "pre-condition");
5875
5876 size_t hr_capacity = hr->capacity();
5877 // We need to read this before we make the region non-humongous,
5878 // otherwise the information will be gone.
5879 uint last_index = hr->last_hc_index();
5880 hr->clear_humongous();
5881 free_region(hr, free_list, par);
5882
5883 uint i = hr->hrm_index() + 1;
5884 while (i < last_index) {
5885 HeapRegion* curr_hr = region_at(i);
5886 assert(curr_hr->is_continues_humongous(), "invariant");
5887 curr_hr->clear_humongous();
5888 free_region(curr_hr, free_list, par);
5889 i += 1;
5890 }
5891 }
5892
5893 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5894 const HeapRegionSetCount& humongous_regions_removed) {
5895 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5896 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5897 _old_set.bulk_remove(old_regions_removed);
5898 _humongous_set.bulk_remove(humongous_regions_removed);
5899 }
5900
5901 }
5902
5903 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5904 assert(list != NULL, "list can't be null");
5905 if (!list->is_empty()) {
5906 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5907 _hrm.insert_list_into_free_list(list);
5908 }
5909 }
5910
5911 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5912 _allocator->decrease_used(bytes);
5913 }
5914
5915 class G1ParCleanupCTTask : public AbstractGangTask {
5916 G1SATBCardTableModRefBS* _ct_bs;
5917 G1CollectedHeap* _g1h;
5918 HeapRegion* volatile _su_head;
5919 public:
5920 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5921 G1CollectedHeap* g1h) :
5922 AbstractGangTask("G1 Par Cleanup CT Task"),
5923 _ct_bs(ct_bs), _g1h(g1h) { }
5924
5925 void work(uint worker_id) {
5926 HeapRegion* r;
5927 while (r = _g1h->pop_dirty_cards_region()) {
5928 clear_cards(r);
5929 }
5930 }
5931
5932 void clear_cards(HeapRegion* r) {
5933 // Cards of the survivors should have already been dirtied.
5934 if (!r->is_survivor()) {
5935 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5936 }
5937 }
5938 };
5939
5940 #ifndef PRODUCT
5941 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5942 G1CollectedHeap* _g1h;
5943 G1SATBCardTableModRefBS* _ct_bs;
5944 public:
5945 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5946 : _g1h(g1h), _ct_bs(ct_bs) { }
5947 virtual bool doHeapRegion(HeapRegion* r) {
5948 if (r->is_survivor()) {
5949 _g1h->verify_dirty_region(r);
5950 } else {
5951 _g1h->verify_not_dirty_region(r);
5952 }
5953 return false;
5954 }
5955 };
5956
5957 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5958 // All of the region should be clean.
5959 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5960 MemRegion mr(hr->bottom(), hr->end());
5961 ct_bs->verify_not_dirty_region(mr);
5962 }
5963
5964 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5965 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5966 // dirty allocated blocks as they allocate them. The thread that
5967 // retires each region and replaces it with a new one will do a
5968 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5969 // not dirty that area (one less thing to have to do while holding
5970 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5971 // is dirty.
5972 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5973 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5974 if (hr->is_young()) {
5975 ct_bs->verify_g1_young_region(mr);
5976 } else {
5977 ct_bs->verify_dirty_region(mr);
5978 }
5979 }
5980
5981 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5982 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5983 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5984 verify_dirty_region(hr);
5985 }
5986 }
5987
5988 void G1CollectedHeap::verify_dirty_young_regions() {
5989 verify_dirty_young_list(_young_list->first_region());
5990 }
5991
5992 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5993 HeapWord* tams, HeapWord* end) {
5994 guarantee(tams <= end,
5995 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5996 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5997 if (result < end) {
5998 gclog_or_tty->cr();
5999 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6000 bitmap_name, result);
6001 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6002 bitmap_name, tams, end);
6003 return false;
6004 }
6005 return true;
6006 }
6007
6008 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6009 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6010 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6011
6012 HeapWord* bottom = hr->bottom();
6013 HeapWord* ptams = hr->prev_top_at_mark_start();
6014 HeapWord* ntams = hr->next_top_at_mark_start();
6015 HeapWord* end = hr->end();
6016
6017 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6018
6019 bool res_n = true;
6020 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6021 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6022 // if we happen to be in that state.
6023 if (mark_in_progress() || !_cmThread->in_progress()) {
6024 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6025 }
6026 if (!res_p || !res_n) {
6027 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6028 HR_FORMAT_PARAMS(hr));
6029 gclog_or_tty->print_cr("#### Caller: %s", caller);
6030 return false;
6031 }
6032 return true;
6033 }
6034
6035 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6036 if (!G1VerifyBitmaps) return;
6037
6038 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6039 }
6040
6041 class G1VerifyBitmapClosure : public HeapRegionClosure {
6042 private:
6043 const char* _caller;
6044 G1CollectedHeap* _g1h;
6045 bool _failures;
6046
6047 public:
6048 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6049 _caller(caller), _g1h(g1h), _failures(false) { }
6050
6051 bool failures() { return _failures; }
6052
6053 virtual bool doHeapRegion(HeapRegion* hr) {
6054 if (hr->is_continues_humongous()) return false;
6055
6056 bool result = _g1h->verify_bitmaps(_caller, hr);
6057 if (!result) {
6058 _failures = true;
6059 }
6060 return false;
6061 }
6062 };
6063
6064 void G1CollectedHeap::check_bitmaps(const char* caller) {
6065 if (!G1VerifyBitmaps) return;
6066
6067 G1VerifyBitmapClosure cl(caller, this);
6068 heap_region_iterate(&cl);
6069 guarantee(!cl.failures(), "bitmap verification");
6070 }
6071 #endif // PRODUCT
6072
6073 void G1CollectedHeap::cleanUpCardTable() {
6074 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6075 double start = os::elapsedTime();
6076
6077 {
6078 // Iterate over the dirty cards region list.
6079 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6080
6081 if (G1CollectedHeap::use_parallel_gc_threads()) {
6082 set_par_threads();
6083 workers()->run_task(&cleanup_task);
6084 set_par_threads(0);
6085 } else {
6086 while (_dirty_cards_region_list) {
6087 HeapRegion* r = _dirty_cards_region_list;
6088 cleanup_task.clear_cards(r);
6089 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6090 if (_dirty_cards_region_list == r) {
6091 // The last region.
6092 _dirty_cards_region_list = NULL;
6093 }
6094 r->set_next_dirty_cards_region(NULL);
6095 }
6096 }
6097 #ifndef PRODUCT
6098 if (G1VerifyCTCleanup || VerifyAfterGC) {
6099 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6100 heap_region_iterate(&cleanup_verifier);
6101 }
6102 #endif
6103 }
6104
6105 double elapsed = os::elapsedTime() - start;
6106 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6107 }
6108
6109 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6110 size_t pre_used = 0;
6111 FreeRegionList local_free_list("Local List for CSet Freeing");
6112
6113 double young_time_ms = 0.0;
6114 double non_young_time_ms = 0.0;
6115
6116 // Since the collection set is a superset of the the young list,
6117 // all we need to do to clear the young list is clear its
6118 // head and length, and unlink any young regions in the code below
6119 _young_list->clear();
6120
6121 G1CollectorPolicy* policy = g1_policy();
6122
6123 double start_sec = os::elapsedTime();
6124 bool non_young = true;
6125
6126 HeapRegion* cur = cs_head;
6127 int age_bound = -1;
6128 size_t rs_lengths = 0;
6129
6130 while (cur != NULL) {
6131 assert(!is_on_master_free_list(cur), "sanity");
6132 if (non_young) {
6133 if (cur->is_young()) {
6134 double end_sec = os::elapsedTime();
6135 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6136 non_young_time_ms += elapsed_ms;
6137
6138 start_sec = os::elapsedTime();
6139 non_young = false;
6140 }
6141 } else {
6142 if (!cur->is_young()) {
6143 double end_sec = os::elapsedTime();
6144 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6145 young_time_ms += elapsed_ms;
6146
6147 start_sec = os::elapsedTime();
6148 non_young = true;
6149 }
6150 }
6151
6152 rs_lengths += cur->rem_set()->occupied_locked();
6153
6154 HeapRegion* next = cur->next_in_collection_set();
6155 assert(cur->in_collection_set(), "bad CS");
6156 cur->set_next_in_collection_set(NULL);
6157 cur->set_in_collection_set(false);
6158
6159 if (cur->is_young()) {
6160 int index = cur->young_index_in_cset();
6161 assert(index != -1, "invariant");
6162 assert((uint) index < policy->young_cset_region_length(), "invariant");
6163 size_t words_survived = _surviving_young_words[index];
6164 cur->record_surv_words_in_group(words_survived);
6165
6166 // At this point the we have 'popped' cur from the collection set
6167 // (linked via next_in_collection_set()) but it is still in the
6168 // young list (linked via next_young_region()). Clear the
6169 // _next_young_region field.
6170 cur->set_next_young_region(NULL);
6171 } else {
6172 int index = cur->young_index_in_cset();
6173 assert(index == -1, "invariant");
6174 }
6175
6176 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6177 (!cur->is_young() && cur->young_index_in_cset() == -1),
6178 "invariant" );
6179
6180 if (!cur->evacuation_failed()) {
6181 MemRegion used_mr = cur->used_region();
6182
6183 // And the region is empty.
6184 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6185 pre_used += cur->used();
6186 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6187 } else {
6188 cur->uninstall_surv_rate_group();
6189 if (cur->is_young()) {
6190 cur->set_young_index_in_cset(-1);
6191 }
6192 cur->set_evacuation_failed(false);
6193 // The region is now considered to be old.
6194 cur->set_old();
6195 _old_set.add(cur);
6196 evacuation_info.increment_collectionset_used_after(cur->used());
6197 }
6198 cur = next;
6199 }
6200
6201 evacuation_info.set_regions_freed(local_free_list.length());
6202 policy->record_max_rs_lengths(rs_lengths);
6203 policy->cset_regions_freed();
6204
6205 double end_sec = os::elapsedTime();
6206 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6207
6208 if (non_young) {
6209 non_young_time_ms += elapsed_ms;
6210 } else {
6211 young_time_ms += elapsed_ms;
6212 }
6213
6214 prepend_to_freelist(&local_free_list);
6215 decrement_summary_bytes(pre_used);
6216 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6217 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6218 }
6219
6220 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6221 private:
6222 FreeRegionList* _free_region_list;
6223 HeapRegionSet* _proxy_set;
6224 HeapRegionSetCount _humongous_regions_removed;
6225 size_t _freed_bytes;
6226 public:
6227
6228 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6229 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6230 }
6231
6232 virtual bool doHeapRegion(HeapRegion* r) {
6233 if (!r->is_starts_humongous()) {
6234 return false;
6235 }
6236
6237 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6238
6239 oop obj = (oop)r->bottom();
6240 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6241
6242 // The following checks whether the humongous object is live are sufficient.
6243 // The main additional check (in addition to having a reference from the roots
6244 // or the young gen) is whether the humongous object has a remembered set entry.
6245 //
6246 // A humongous object cannot be live if there is no remembered set for it
6247 // because:
6248 // - there can be no references from within humongous starts regions referencing
6249 // the object because we never allocate other objects into them.
6250 // (I.e. there are no intra-region references that may be missed by the
6251 // remembered set)
6252 // - as soon there is a remembered set entry to the humongous starts region
6253 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6254 // until the end of a concurrent mark.
6255 //
6256 // It is not required to check whether the object has been found dead by marking
6257 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6258 // all objects allocated during that time are considered live.
6259 // SATB marking is even more conservative than the remembered set.
6260 // So if at this point in the collection there is no remembered set entry,
6261 // nobody has a reference to it.
6262 // At the start of collection we flush all refinement logs, and remembered sets
6263 // are completely up-to-date wrt to references to the humongous object.
6264 //
6265 // Other implementation considerations:
6266 // - never consider object arrays: while they are a valid target, they have not
6267 // been observed to be used as temporary objects.
6268 // - they would also pose considerable effort for cleaning up the the remembered
6269 // sets.
6270 // While this cleanup is not strictly necessary to be done (or done instantly),
6271 // given that their occurrence is very low, this saves us this additional
6272 // complexity.
6273 uint region_idx = r->hrm_index();
6274 if (g1h->humongous_is_live(region_idx) ||
6275 g1h->humongous_region_is_always_live(region_idx)) {
6276
6277 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6278 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",
6279 r->is_humongous(),
6280 region_idx,
6281 r->rem_set()->occupied(),
6282 r->rem_set()->strong_code_roots_list_length(),
6283 next_bitmap->isMarked(r->bottom()),
6284 g1h->humongous_is_live(region_idx),
6285 obj->is_objArray()
6286 );
6287 }
6288
6289 return false;
6290 }
6291
6292 guarantee(!obj->is_objArray(),
6293 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6294 r->bottom()));
6295
6296 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6297 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",
6298 r->is_humongous(),
6299 r->bottom(),
6300 region_idx,
6301 r->region_num(),
6302 r->rem_set()->occupied(),
6303 r->rem_set()->strong_code_roots_list_length(),
6304 next_bitmap->isMarked(r->bottom()),
6305 g1h->humongous_is_live(region_idx),
6306 obj->is_objArray()
6307 );
6308 }
6309 // Need to clear mark bit of the humongous object if already set.
6310 if (next_bitmap->isMarked(r->bottom())) {
6311 next_bitmap->clear(r->bottom());
6312 }
6313 _freed_bytes += r->used();
6314 r->set_containing_set(NULL);
6315 _humongous_regions_removed.increment(1u, r->capacity());
6316 g1h->free_humongous_region(r, _free_region_list, false);
6317
6318 return false;
6319 }
6320
6321 HeapRegionSetCount& humongous_free_count() {
6322 return _humongous_regions_removed;
6323 }
6324
6325 size_t bytes_freed() const {
6326 return _freed_bytes;
6327 }
6328
6329 size_t humongous_reclaimed() const {
6330 return _humongous_regions_removed.length();
6331 }
6332 };
6333
6334 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6335 assert_at_safepoint(true);
6336
6337 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) {
6338 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6339 return;
6340 }
6341
6342 double start_time = os::elapsedTime();
6343
6344 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6345
6346 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6347 heap_region_iterate(&cl);
6348
6349 HeapRegionSetCount empty_set;
6350 remove_from_old_sets(empty_set, cl.humongous_free_count());
6351
6352 G1HRPrinter* hr_printer = _g1h->hr_printer();
6353 if (hr_printer->is_active()) {
6354 FreeRegionListIterator iter(&local_cleanup_list);
6355 while (iter.more_available()) {
6356 HeapRegion* hr = iter.get_next();
6357 hr_printer->cleanup(hr);
6358 }
6359 }
6360
6361 prepend_to_freelist(&local_cleanup_list);
6362 decrement_summary_bytes(cl.bytes_freed());
6363
6364 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6365 cl.humongous_reclaimed());
6366 }
6367
6368 // This routine is similar to the above but does not record
6369 // any policy statistics or update free lists; we are abandoning
6370 // the current incremental collection set in preparation of a
6371 // full collection. After the full GC we will start to build up
6372 // the incremental collection set again.
6373 // This is only called when we're doing a full collection
6374 // and is immediately followed by the tearing down of the young list.
6375
6376 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6377 HeapRegion* cur = cs_head;
6378
6379 while (cur != NULL) {
6380 HeapRegion* next = cur->next_in_collection_set();
6381 assert(cur->in_collection_set(), "bad CS");
6382 cur->set_next_in_collection_set(NULL);
6383 cur->set_in_collection_set(false);
6384 cur->set_young_index_in_cset(-1);
6385 cur = next;
6386 }
6387 }
6388
6389 void G1CollectedHeap::set_free_regions_coming() {
6390 if (G1ConcRegionFreeingVerbose) {
6391 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6392 "setting free regions coming");
6393 }
6394
6395 assert(!free_regions_coming(), "pre-condition");
6396 _free_regions_coming = true;
6397 }
6398
6399 void G1CollectedHeap::reset_free_regions_coming() {
6400 assert(free_regions_coming(), "pre-condition");
6401
6402 {
6403 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6404 _free_regions_coming = false;
6405 SecondaryFreeList_lock->notify_all();
6406 }
6407
6408 if (G1ConcRegionFreeingVerbose) {
6409 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6410 "reset free regions coming");
6411 }
6412 }
6413
6414 void G1CollectedHeap::wait_while_free_regions_coming() {
6415 // Most of the time we won't have to wait, so let's do a quick test
6416 // first before we take the lock.
6417 if (!free_regions_coming()) {
6418 return;
6419 }
6420
6421 if (G1ConcRegionFreeingVerbose) {
6422 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6423 "waiting for free regions");
6424 }
6425
6426 {
6427 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6428 while (free_regions_coming()) {
6429 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6430 }
6431 }
6432
6433 if (G1ConcRegionFreeingVerbose) {
6434 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6435 "done waiting for free regions");
6436 }
6437 }
6438
6439 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6440 assert(heap_lock_held_for_gc(),
6441 "the heap lock should already be held by or for this thread");
6442 _young_list->push_region(hr);
6443 }
6444
6445 class NoYoungRegionsClosure: public HeapRegionClosure {
6446 private:
6447 bool _success;
6448 public:
6449 NoYoungRegionsClosure() : _success(true) { }
6450 bool doHeapRegion(HeapRegion* r) {
6451 if (r->is_young()) {
6452 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6453 r->bottom(), r->end());
6454 _success = false;
6455 }
6456 return false;
6457 }
6458 bool success() { return _success; }
6459 };
6460
6461 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6462 bool ret = _young_list->check_list_empty(check_sample);
6463
6464 if (check_heap) {
6465 NoYoungRegionsClosure closure;
6466 heap_region_iterate(&closure);
6467 ret = ret && closure.success();
6468 }
6469
6470 return ret;
6471 }
6472
6473 class TearDownRegionSetsClosure : public HeapRegionClosure {
6474 private:
6475 HeapRegionSet *_old_set;
6476
6477 public:
6478 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6479
6480 bool doHeapRegion(HeapRegion* r) {
6481 if (r->is_old()) {
6482 _old_set->remove(r);
6483 } else {
6484 // We ignore free regions, we'll empty the free list afterwards.
6485 // We ignore young regions, we'll empty the young list afterwards.
6486 // We ignore humongous regions, we're not tearing down the
6487 // humongous regions set.
6488 assert(r->is_free() || r->is_young() || r->is_humongous(),
6489 "it cannot be another type");
6490 }
6491 return false;
6492 }
6493
6494 ~TearDownRegionSetsClosure() {
6495 assert(_old_set->is_empty(), "post-condition");
6496 }
6497 };
6498
6499 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6500 assert_at_safepoint(true /* should_be_vm_thread */);
6501
6502 if (!free_list_only) {
6503 TearDownRegionSetsClosure cl(&_old_set);
6504 heap_region_iterate(&cl);
6505
6506 // Note that emptying the _young_list is postponed and instead done as
6507 // the first step when rebuilding the regions sets again. The reason for
6508 // this is that during a full GC string deduplication needs to know if
6509 // a collected region was young or old when the full GC was initiated.
6510 }
6511 _hrm.remove_all_free_regions();
6512 }
6513
6514 class RebuildRegionSetsClosure : public HeapRegionClosure {
6515 private:
6516 bool _free_list_only;
6517 HeapRegionSet* _old_set;
6518 HeapRegionManager* _hrm;
6519 size_t _total_used;
6520
6521 public:
6522 RebuildRegionSetsClosure(bool free_list_only,
6523 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6524 _free_list_only(free_list_only),
6525 _old_set(old_set), _hrm(hrm), _total_used(0) {
6526 assert(_hrm->num_free_regions() == 0, "pre-condition");
6527 if (!free_list_only) {
6528 assert(_old_set->is_empty(), "pre-condition");
6529 }
6530 }
6531
6532 bool doHeapRegion(HeapRegion* r) {
6533 if (r->is_continues_humongous()) {
6534 return false;
6535 }
6536
6537 if (r->is_empty()) {
6538 // Add free regions to the free list
6539 r->set_free();
6540 r->set_allocation_context(AllocationContext::system());
6541 _hrm->insert_into_free_list(r);
6542 } else if (!_free_list_only) {
6543 assert(!r->is_young(), "we should not come across young regions");
6544
6545 if (r->is_humongous()) {
6546 // We ignore humongous regions, we left the humongous set unchanged
6547 } else {
6548 // Objects that were compacted would have ended up on regions
6549 // that were previously old or free.
6550 assert(r->is_free() || r->is_old(), "invariant");
6551 // We now consider them old, so register as such.
6552 r->set_old();
6553 _old_set->add(r);
6554 }
6555 _total_used += r->used();
6556 }
6557
6558 return false;
6559 }
6560
6561 size_t total_used() {
6562 return _total_used;
6563 }
6564 };
6565
6566 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6567 assert_at_safepoint(true /* should_be_vm_thread */);
6568
6569 if (!free_list_only) {
6570 _young_list->empty_list();
6571 }
6572
6573 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6574 heap_region_iterate(&cl);
6575
6576 if (!free_list_only) {
6577 _allocator->set_used(cl.total_used());
6578 }
6579 assert(_allocator->used_unlocked() == recalculate_used(),
6580 err_msg("inconsistent _allocator->used_unlocked(), "
6581 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6582 _allocator->used_unlocked(), recalculate_used()));
6583 }
6584
6585 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6586 _refine_cte_cl->set_concurrent(concurrent);
6587 }
6588
6589 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6590 HeapRegion* hr = heap_region_containing(p);
6591 return hr->is_in(p);
6592 }
6593
6594 // Methods for the mutator alloc region
6595
6596 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6597 bool force) {
6598 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6599 assert(!force || g1_policy()->can_expand_young_list(),
6600 "if force is true we should be able to expand the young list");
6601 bool young_list_full = g1_policy()->is_young_list_full();
6602 if (force || !young_list_full) {
6603 HeapRegion* new_alloc_region = new_region(word_size,
6604 false /* is_old */,
6605 false /* do_expand */);
6606 if (new_alloc_region != NULL) {
6607 set_region_short_lived_locked(new_alloc_region);
6608 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6609 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6610 return new_alloc_region;
6611 }
6612 }
6613 return NULL;
6614 }
6615
6616 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6617 size_t allocated_bytes) {
6618 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6619 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6620
6621 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6622 _allocator->increase_used(allocated_bytes);
6623 _hr_printer.retire(alloc_region);
6624 // We update the eden sizes here, when the region is retired,
6625 // instead of when it's allocated, since this is the point that its
6626 // used space has been recored in _summary_bytes_used.
6627 g1mm()->update_eden_size();
6628 }
6629
6630 void G1CollectedHeap::set_par_threads() {
6631 // Don't change the number of workers. Use the value previously set
6632 // in the workgroup.
6633 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6634 uint n_workers = workers()->active_workers();
6635 assert(UseDynamicNumberOfGCThreads ||
6636 n_workers == workers()->total_workers(),
6637 "Otherwise should be using the total number of workers");
6638 if (n_workers == 0) {
6639 assert(false, "Should have been set in prior evacuation pause.");
6640 n_workers = ParallelGCThreads;
6641 workers()->set_active_workers(n_workers);
6642 }
6643 set_par_threads(n_workers);
6644 }
6645
6646 // Methods for the GC alloc regions
6647
6648 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6649 uint count,
6650 GCAllocPurpose ap) {
6651 assert(FreeList_lock->owned_by_self(), "pre-condition");
6652
6653 if (count < g1_policy()->max_regions(ap)) {
6654 bool survivor = (ap == GCAllocForSurvived);
6655 HeapRegion* new_alloc_region = new_region(word_size,
6656 !survivor,
6657 true /* do_expand */);
6658 if (new_alloc_region != NULL) {
6659 // We really only need to do this for old regions given that we
6660 // should never scan survivors. But it doesn't hurt to do it
6661 // for survivors too.
6662 new_alloc_region->record_top_and_timestamp();
6663 if (survivor) {
6664 new_alloc_region->set_survivor();
6665 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6666 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6667 } else {
6668 new_alloc_region->set_old();
6669 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6670 check_bitmaps("Old Region Allocation", new_alloc_region);
6671 }
6672 bool during_im = g1_policy()->during_initial_mark_pause();
6673 new_alloc_region->note_start_of_copying(during_im);
6674 return new_alloc_region;
6675 } else {
6676 g1_policy()->note_alloc_region_limit_reached(ap);
6677 }
6678 }
6679 return NULL;
6680 }
6681
6682 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6683 size_t allocated_bytes,
6684 GCAllocPurpose ap) {
6685 bool during_im = g1_policy()->during_initial_mark_pause();
6686 alloc_region->note_end_of_copying(during_im);
6687 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6688 if (ap == GCAllocForSurvived) {
6689 young_list()->add_survivor_region(alloc_region);
6690 } else {
6691 _old_set.add(alloc_region);
6692 }
6693 _hr_printer.retire(alloc_region);
6694 }
6695
6696 // Heap region set verification
6697
6698 class VerifyRegionListsClosure : public HeapRegionClosure {
6699 private:
6700 HeapRegionSet* _old_set;
6701 HeapRegionSet* _humongous_set;
6702 HeapRegionManager* _hrm;
6703
6704 public:
6705 HeapRegionSetCount _old_count;
6706 HeapRegionSetCount _humongous_count;
6707 HeapRegionSetCount _free_count;
6708
6709 VerifyRegionListsClosure(HeapRegionSet* old_set,
6710 HeapRegionSet* humongous_set,
6711 HeapRegionManager* hrm) :
6712 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6713 _old_count(), _humongous_count(), _free_count(){ }
6714
6715 bool doHeapRegion(HeapRegion* hr) {
6716 if (hr->is_continues_humongous()) {
6717 return false;
6718 }
6719
6720 if (hr->is_young()) {
6721 // TODO
6722 } else if (hr->is_starts_humongous()) {
6723 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6724 _humongous_count.increment(1u, hr->capacity());
6725 } else if (hr->is_empty()) {
6726 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6727 _free_count.increment(1u, hr->capacity());
6728 } else if (hr->is_old()) {
6729 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6730 _old_count.increment(1u, hr->capacity());
6731 } else {
6732 ShouldNotReachHere();
6733 }
6734 return false;
6735 }
6736
6737 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6738 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6739 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6740 old_set->total_capacity_bytes(), _old_count.capacity()));
6741
6742 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6743 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6744 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6745
6746 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()));
6747 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6748 free_list->total_capacity_bytes(), _free_count.capacity()));
6749 }
6750 };
6751
6752 void G1CollectedHeap::verify_region_sets() {
6753 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6754
6755 // First, check the explicit lists.
6756 _hrm.verify();
6757 {
6758 // Given that a concurrent operation might be adding regions to
6759 // the secondary free list we have to take the lock before
6760 // verifying it.
6761 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6762 _secondary_free_list.verify_list();
6763 }
6764
6765 // If a concurrent region freeing operation is in progress it will
6766 // be difficult to correctly attributed any free regions we come
6767 // across to the correct free list given that they might belong to
6768 // one of several (free_list, secondary_free_list, any local lists,
6769 // etc.). So, if that's the case we will skip the rest of the
6770 // verification operation. Alternatively, waiting for the concurrent
6771 // operation to complete will have a non-trivial effect on the GC's
6772 // operation (no concurrent operation will last longer than the
6773 // interval between two calls to verification) and it might hide
6774 // any issues that we would like to catch during testing.
6775 if (free_regions_coming()) {
6776 return;
6777 }
6778
6779 // Make sure we append the secondary_free_list on the free_list so
6780 // that all free regions we will come across can be safely
6781 // attributed to the free_list.
6782 append_secondary_free_list_if_not_empty_with_lock();
6783
6784 // Finally, make sure that the region accounting in the lists is
6785 // consistent with what we see in the heap.
6786
6787 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6788 heap_region_iterate(&cl);
6789 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6790 }
6791
6792 // Optimized nmethod scanning
6793
6794 class RegisterNMethodOopClosure: public OopClosure {
6795 G1CollectedHeap* _g1h;
6796 nmethod* _nm;
6797
6798 template <class T> void do_oop_work(T* p) {
6799 T heap_oop = oopDesc::load_heap_oop(p);
6800 if (!oopDesc::is_null(heap_oop)) {
6801 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6802 HeapRegion* hr = _g1h->heap_region_containing(obj);
6803 assert(!hr->is_continues_humongous(),
6804 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6805 " starting at "HR_FORMAT,
6806 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6807
6808 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6809 hr->add_strong_code_root_locked(_nm);
6810 }
6811 }
6812
6813 public:
6814 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6815 _g1h(g1h), _nm(nm) {}
6816
6817 void do_oop(oop* p) { do_oop_work(p); }
6818 void do_oop(narrowOop* p) { do_oop_work(p); }
6819 };
6820
6821 class UnregisterNMethodOopClosure: public OopClosure {
6822 G1CollectedHeap* _g1h;
6823 nmethod* _nm;
6824
6825 template <class T> void do_oop_work(T* p) {
6826 T heap_oop = oopDesc::load_heap_oop(p);
6827 if (!oopDesc::is_null(heap_oop)) {
6828 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6829 HeapRegion* hr = _g1h->heap_region_containing(obj);
6830 assert(!hr->is_continues_humongous(),
6831 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6832 " starting at "HR_FORMAT,
6833 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6834
6835 hr->remove_strong_code_root(_nm);
6836 }
6837 }
6838
6839 public:
6840 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6841 _g1h(g1h), _nm(nm) {}
6842
6843 void do_oop(oop* p) { do_oop_work(p); }
6844 void do_oop(narrowOop* p) { do_oop_work(p); }
6845 };
6846
6847 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6848 CollectedHeap::register_nmethod(nm);
6849
6850 guarantee(nm != NULL, "sanity");
6851 RegisterNMethodOopClosure reg_cl(this, nm);
6852 nm->oops_do(®_cl);
6853 }
6854
6855 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6856 CollectedHeap::unregister_nmethod(nm);
6857
6858 guarantee(nm != NULL, "sanity");
6859 UnregisterNMethodOopClosure reg_cl(this, nm);
6860 nm->oops_do(®_cl, true);
6861 }
6862
6863 void G1CollectedHeap::purge_code_root_memory() {
6864 double purge_start = os::elapsedTime();
6865 G1CodeRootSet::purge();
6866 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6867 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6868 }
6869
6870 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6871 G1CollectedHeap* _g1h;
6872
6873 public:
6874 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6875 _g1h(g1h) {}
6876
6877 void do_code_blob(CodeBlob* cb) {
6878 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6879 if (nm == NULL) {
6880 return;
6881 }
6882
6883 if (ScavengeRootsInCode) {
6884 _g1h->register_nmethod(nm);
6885 }
6886 }
6887 };
6888
6889 void G1CollectedHeap::rebuild_strong_code_roots() {
6890 RebuildStrongCodeRootClosure blob_cl(this);
6891 CodeCache::blobs_do(&blob_cl);
6892 }