1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 #define ATTRIBUTE_PRINTF(x,y) // FIXME, formats are a mess.
27 #endif
28
29 #include "precompiled.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "gc_implementation/g1/bufferingOopClosure.hpp"
33 #include "gc_implementation/g1/concurrentG1Refine.hpp"
34 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
35 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
36 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
37 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
38 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
39 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
40 #include "gc_implementation/g1/g1EvacFailure.hpp"
41 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
42 #include "gc_implementation/g1/g1Log.hpp"
43 #include "gc_implementation/g1/g1MarkSweep.hpp"
44 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
45 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
46 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
47 #include "gc_implementation/g1/g1RemSet.inline.hpp"
48 #include "gc_implementation/g1/g1StringDedup.hpp"
49 #include "gc_implementation/g1/g1YCTypes.hpp"
50 #include "gc_implementation/g1/heapRegion.inline.hpp"
51 #include "gc_implementation/g1/heapRegionRemSet.hpp"
52 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
53 #include "gc_implementation/g1/vm_operations_g1.hpp"
54 #include "gc_implementation/shared/gcHeapSummary.hpp"
55 #include "gc_implementation/shared/gcTimer.hpp"
56 #include "gc_implementation/shared/gcTrace.hpp"
57 #include "gc_implementation/shared/gcTraceTime.hpp"
58 #include "gc_implementation/shared/isGCActiveMark.hpp"
59 #include "memory/allocation.hpp"
60 #include "memory/gcLocker.inline.hpp"
61 #include "memory/generationSpec.hpp"
62 #include "memory/iterator.hpp"
63 #include "memory/referenceProcessor.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "oops/oop.pcgc.inline.hpp"
66 #include "runtime/orderAccess.inline.hpp"
67 #include "runtime/vmThread.hpp"
68
69 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
70
71 // turn it on so that the contents of the young list (scan-only /
72 // to-be-collected) are printed at "strategic" points before / during
73 // / after the collection --- this is useful for debugging
74 #define YOUNG_LIST_VERBOSE 0
75 // CURRENT STATUS
76 // This file is under construction. Search for "FIXME".
77
78 // INVARIANTS/NOTES
79 //
80 // All allocation activity covered by the G1CollectedHeap interface is
81 // serialized by acquiring the HeapLock. This happens in mem_allocate
82 // and allocate_new_tlab, which are the "entry" points to the
83 // allocation code from the rest of the JVM. (Note that this does not
84 // apply to TLAB allocation, which is not part of this interface: it
85 // is done by clients of this interface.)
86
87 // Notes on implementation of parallelism in different tasks.
88 //
89 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
90 // The number of GC workers is passed to heap_region_par_iterate_chunked().
91 // It does use run_task() which sets _n_workers in the task.
92 // G1ParTask executes g1_process_roots() ->
93 // SharedHeap::process_roots() which calls eventually to
94 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
95 // SequentialSubTasksDone. SharedHeap::process_roots() also
96 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
97 //
98
99 // Local to this file.
100
101 class RefineCardTableEntryClosure: public CardTableEntryClosure {
102 bool _concurrent;
103 public:
104 RefineCardTableEntryClosure() : _concurrent(true) { }
105
106 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
107 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
108 // This path is executed by the concurrent refine or mutator threads,
109 // concurrently, and so we do not care if card_ptr contains references
110 // that point into the collection set.
111 assert(!oops_into_cset, "should be");
112
113 if (_concurrent && SuspendibleThreadSet::should_yield()) {
114 // Caller will actually yield.
115 return false;
116 }
117 // Otherwise, we finished successfully; return true.
118 return true;
119 }
120
121 void set_concurrent(bool b) { _concurrent = b; }
122 };
123
124
125 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
126 size_t _num_processed;
127 CardTableModRefBS* _ctbs;
128 int _histo[256];
129
130 public:
131 ClearLoggedCardTableEntryClosure() :
132 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
133 {
134 for (int i = 0; i < 256; i++) _histo[i] = 0;
135 }
136
137 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
138 unsigned char* ujb = (unsigned char*)card_ptr;
139 int ind = (int)(*ujb);
140 _histo[ind]++;
141
142 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
143 _num_processed++;
144
145 return true;
146 }
147
148 size_t num_processed() { return _num_processed; }
149
150 void print_histo() {
151 gclog_or_tty->print_cr("Card table value histogram:");
152 for (int i = 0; i < 256; i++) {
153 if (_histo[i] != 0) {
154 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
155 }
156 }
157 }
158 };
159
160 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
161 private:
162 size_t _num_processed;
163
164 public:
165 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
166
167 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
168 *card_ptr = CardTableModRefBS::dirty_card_val();
169 _num_processed++;
170 return true;
171 }
172
173 size_t num_processed() const { return _num_processed; }
174 };
175
176 YoungList::YoungList(G1CollectedHeap* g1h) :
177 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
178 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
179 guarantee(check_list_empty(false), "just making sure...");
180 }
181
182 void YoungList::push_region(HeapRegion *hr) {
183 assert(!hr->is_young(), "should not already be young");
184 assert(hr->get_next_young_region() == NULL, "cause it should!");
185
186 hr->set_next_young_region(_head);
187 _head = hr;
188
189 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
190 ++_length;
191 }
192
193 void YoungList::add_survivor_region(HeapRegion* hr) {
194 assert(hr->is_survivor(), "should be flagged as survivor region");
195 assert(hr->get_next_young_region() == NULL, "cause it should!");
196
197 hr->set_next_young_region(_survivor_head);
198 if (_survivor_head == NULL) {
199 _survivor_tail = hr;
200 }
201 _survivor_head = hr;
202 ++_survivor_length;
203 }
204
205 void YoungList::empty_list(HeapRegion* list) {
206 while (list != NULL) {
207 HeapRegion* next = list->get_next_young_region();
208 list->set_next_young_region(NULL);
209 list->uninstall_surv_rate_group();
210 list->set_not_young();
211 list = next;
212 }
213 }
214
215 void YoungList::empty_list() {
216 assert(check_list_well_formed(), "young list should be well formed");
217
218 empty_list(_head);
219 _head = NULL;
220 _length = 0;
221
222 empty_list(_survivor_head);
223 _survivor_head = NULL;
224 _survivor_tail = NULL;
225 _survivor_length = 0;
226
227 _last_sampled_rs_lengths = 0;
228
229 assert(check_list_empty(false), "just making sure...");
230 }
231
232 bool YoungList::check_list_well_formed() {
233 bool ret = true;
234
235 uint length = 0;
236 HeapRegion* curr = _head;
237 HeapRegion* last = NULL;
238 while (curr != NULL) {
239 if (!curr->is_young()) {
240 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
241 "incorrectly tagged (y: %d, surv: %d)",
242 curr->bottom(), curr->end(),
243 curr->is_young(), curr->is_survivor());
244 ret = false;
245 }
246 ++length;
247 last = curr;
248 curr = curr->get_next_young_region();
249 }
250 ret = ret && (length == _length);
251
252 if (!ret) {
253 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
254 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
255 length, _length);
256 }
257
258 return ret;
259 }
260
261 bool YoungList::check_list_empty(bool check_sample) {
262 bool ret = true;
263
264 if (_length != 0) {
265 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
266 _length);
267 ret = false;
268 }
269 if (check_sample && _last_sampled_rs_lengths != 0) {
270 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
271 ret = false;
272 }
273 if (_head != NULL) {
274 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
275 ret = false;
276 }
277 if (!ret) {
278 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
279 }
280
281 return ret;
282 }
283
284 void
285 YoungList::rs_length_sampling_init() {
286 _sampled_rs_lengths = 0;
287 _curr = _head;
288 }
289
290 bool
291 YoungList::rs_length_sampling_more() {
292 return _curr != NULL;
293 }
294
295 void
296 YoungList::rs_length_sampling_next() {
297 assert( _curr != NULL, "invariant" );
298 size_t rs_length = _curr->rem_set()->occupied();
299
300 _sampled_rs_lengths += rs_length;
301
302 // The current region may not yet have been added to the
303 // incremental collection set (it gets added when it is
304 // retired as the current allocation region).
305 if (_curr->in_collection_set()) {
306 // Update the collection set policy information for this region
307 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
308 }
309
310 _curr = _curr->get_next_young_region();
311 if (_curr == NULL) {
312 _last_sampled_rs_lengths = _sampled_rs_lengths;
313 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
314 }
315 }
316
317 void
318 YoungList::reset_auxilary_lists() {
319 guarantee( is_empty(), "young list should be empty" );
320 assert(check_list_well_formed(), "young list should be well formed");
321
322 // Add survivor regions to SurvRateGroup.
323 _g1h->g1_policy()->note_start_adding_survivor_regions();
324 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
325
326 int young_index_in_cset = 0;
327 for (HeapRegion* curr = _survivor_head;
328 curr != NULL;
329 curr = curr->get_next_young_region()) {
330 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
331
332 // The region is a non-empty survivor so let's add it to
333 // the incremental collection set for the next evacuation
334 // pause.
335 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
336 young_index_in_cset += 1;
337 }
338 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
339 _g1h->g1_policy()->note_stop_adding_survivor_regions();
340
341 _head = _survivor_head;
342 _length = _survivor_length;
343 if (_survivor_head != NULL) {
344 assert(_survivor_tail != NULL, "cause it shouldn't be");
345 assert(_survivor_length > 0, "invariant");
346 _survivor_tail->set_next_young_region(NULL);
347 }
348
349 // Don't clear the survivor list handles until the start of
350 // the next evacuation pause - we need it in order to re-tag
351 // the survivor regions from this evacuation pause as 'young'
352 // at the start of the next.
353
354 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
355
356 assert(check_list_well_formed(), "young list should be well formed");
357 }
358
359 void YoungList::print() {
360 HeapRegion* lists[] = {_head, _survivor_head};
361 const char* names[] = {"YOUNG", "SURVIVOR"};
362
363 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
364 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
365 HeapRegion *curr = lists[list];
366 if (curr == NULL)
367 gclog_or_tty->print_cr(" empty");
368 while (curr != NULL) {
369 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
370 HR_FORMAT_PARAMS(curr),
371 curr->prev_top_at_mark_start(),
372 curr->next_top_at_mark_start(),
373 curr->age_in_surv_rate_group_cond());
374 curr = curr->get_next_young_region();
375 }
376 }
377
378 gclog_or_tty->cr();
379 }
380
381 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
382 OtherRegionsTable::invalidate(start_idx, num_regions);
383 }
384
385 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions) {
386 reset_from_card_cache(start_idx, num_regions);
387 }
388
389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
390 {
391 // Claim the right to put the region on the dirty cards region list
392 // by installing a self pointer.
393 HeapRegion* next = hr->get_next_dirty_cards_region();
394 if (next == NULL) {
395 HeapRegion* res = (HeapRegion*)
396 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
397 NULL);
398 if (res == NULL) {
399 HeapRegion* head;
400 do {
401 // Put the region to the dirty cards region list.
402 head = _dirty_cards_region_list;
403 next = (HeapRegion*)
404 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
405 if (next == head) {
406 assert(hr->get_next_dirty_cards_region() == hr,
407 "hr->get_next_dirty_cards_region() != hr");
408 if (next == NULL) {
409 // The last region in the list points to itself.
410 hr->set_next_dirty_cards_region(hr);
411 } else {
412 hr->set_next_dirty_cards_region(next);
413 }
414 }
415 } while (next != head);
416 }
417 }
418 }
419
420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
421 {
422 HeapRegion* head;
423 HeapRegion* hr;
424 do {
425 head = _dirty_cards_region_list;
426 if (head == NULL) {
427 return NULL;
428 }
429 HeapRegion* new_head = head->get_next_dirty_cards_region();
430 if (head == new_head) {
431 // The last region.
432 new_head = NULL;
433 }
434 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
435 head);
436 } while (hr != head);
437 assert(hr != NULL, "invariant");
438 hr->set_next_dirty_cards_region(NULL);
439 return hr;
440 }
441
442 #ifdef ASSERT
443 // A region is added to the collection set as it is retired
444 // so an address p can point to a region which will be in the
445 // collection set but has not yet been retired. This method
446 // therefore is only accurate during a GC pause after all
447 // regions have been retired. It is used for debugging
448 // to check if an nmethod has references to objects that can
449 // be move during a partial collection. Though it can be
450 // inaccurate, it is sufficient for G1 because the conservative
451 // implementation of is_scavengable() for G1 will indicate that
452 // all nmethods must be scanned during a partial collection.
453 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
454 if (p == NULL) {
455 return false;
456 }
457 return heap_region_containing(p)->in_collection_set();
458 }
459 #endif
460
461 // Returns true if the reference points to an object that
462 // can move in an incremental collection.
463 bool G1CollectedHeap::is_scavengable(const void* p) {
464 HeapRegion* hr = heap_region_containing(p);
465 return !hr->isHumongous();
466 }
467
468 void G1CollectedHeap::check_ct_logs_at_safepoint() {
469 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
470 CardTableModRefBS* ct_bs = g1_barrier_set();
471
472 // Count the dirty cards at the start.
473 CountNonCleanMemRegionClosure count1(this);
474 ct_bs->mod_card_iterate(&count1);
475 int orig_count = count1.n();
476
477 // First clear the logged cards.
478 ClearLoggedCardTableEntryClosure clear;
479 dcqs.apply_closure_to_all_completed_buffers(&clear);
480 dcqs.iterate_closure_all_threads(&clear, false);
481 clear.print_histo();
482
483 // Now ensure that there's no dirty cards.
484 CountNonCleanMemRegionClosure count2(this);
485 ct_bs->mod_card_iterate(&count2);
486 if (count2.n() != 0) {
487 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
488 count2.n(), orig_count);
489 }
490 guarantee(count2.n() == 0, "Card table should be clean.");
491
492 RedirtyLoggedCardTableEntryClosure redirty;
493 dcqs.apply_closure_to_all_completed_buffers(&redirty);
494 dcqs.iterate_closure_all_threads(&redirty, false);
495 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
496 clear.num_processed(), orig_count);
497 guarantee(redirty.num_processed() == clear.num_processed(),
498 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
499 redirty.num_processed(), clear.num_processed()));
500
501 CountNonCleanMemRegionClosure count3(this);
502 ct_bs->mod_card_iterate(&count3);
503 if (count3.n() != orig_count) {
504 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
505 orig_count, count3.n());
506 guarantee(count3.n() >= orig_count, "Should have restored them all.");
507 }
508 }
509
510 // Private class members.
511
512 G1CollectedHeap* G1CollectedHeap::_g1h;
513
514 // Private methods.
515
516 HeapRegion*
517 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
518 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
519 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
520 if (!_secondary_free_list.is_empty()) {
521 if (G1ConcRegionFreeingVerbose) {
522 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
523 "secondary_free_list has %u entries",
524 _secondary_free_list.length());
525 }
526 // It looks as if there are free regions available on the
527 // secondary_free_list. Let's move them to the free_list and try
528 // again to allocate from it.
529 append_secondary_free_list();
530
531 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
532 "empty we should have moved at least one entry to the free_list");
533 HeapRegion* res = _hrm.allocate_free_region(is_old);
534 if (G1ConcRegionFreeingVerbose) {
535 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
536 "allocated "HR_FORMAT" from secondary_free_list",
537 HR_FORMAT_PARAMS(res));
538 }
539 return res;
540 }
541
542 // Wait here until we get notified either when (a) there are no
543 // more free regions coming or (b) some regions have been moved on
544 // the secondary_free_list.
545 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
546 }
547
548 if (G1ConcRegionFreeingVerbose) {
549 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
550 "could not allocate from secondary_free_list");
551 }
552 return NULL;
553 }
554
555 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
556 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
557 "the only time we use this to allocate a humongous region is "
558 "when we are allocating a single humongous region");
559
560 HeapRegion* res;
561 if (G1StressConcRegionFreeing) {
562 if (!_secondary_free_list.is_empty()) {
563 if (G1ConcRegionFreeingVerbose) {
564 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
565 "forced to look at the secondary_free_list");
566 }
567 res = new_region_try_secondary_free_list(is_old);
568 if (res != NULL) {
569 return res;
570 }
571 }
572 }
573
574 res = _hrm.allocate_free_region(is_old);
575
576 if (res == NULL) {
577 if (G1ConcRegionFreeingVerbose) {
578 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
579 "res == NULL, trying the secondary_free_list");
580 }
581 res = new_region_try_secondary_free_list(is_old);
582 }
583 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
584 // Currently, only attempts to allocate GC alloc regions set
585 // do_expand to true. So, we should only reach here during a
586 // safepoint. If this assumption changes we might have to
587 // reconsider the use of _expand_heap_after_alloc_failure.
588 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
589
590 ergo_verbose1(ErgoHeapSizing,
591 "attempt heap expansion",
592 ergo_format_reason("region allocation request failed")
593 ergo_format_byte("allocation request"),
594 word_size * HeapWordSize);
595 if (expand(word_size * HeapWordSize)) {
596 // Given that expand() succeeded in expanding the heap, and we
597 // always expand the heap by an amount aligned to the heap
598 // region size, the free list should in theory not be empty.
599 // In either case allocate_free_region() will check for NULL.
600 res = _hrm.allocate_free_region(is_old);
601 } else {
602 _expand_heap_after_alloc_failure = false;
603 }
604 }
605 return res;
606 }
607
608 HeapWord*
609 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
610 uint num_regions,
611 size_t word_size,
612 AllocationContext_t context) {
613 assert(first != G1_NO_HRM_INDEX, "pre-condition");
614 assert(isHumongous(word_size), "word_size should be humongous");
615 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
616
617 // Index of last region in the series + 1.
618 uint last = first + num_regions;
619
620 // We need to initialize the region(s) we just discovered. This is
621 // a bit tricky given that it can happen concurrently with
622 // refinement threads refining cards on these regions and
623 // potentially wanting to refine the BOT as they are scanning
624 // those cards (this can happen shortly after a cleanup; see CR
625 // 6991377). So we have to set up the region(s) carefully and in
626 // a specific order.
627
628 // The word size sum of all the regions we will allocate.
629 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
630 assert(word_size <= word_size_sum, "sanity");
631
632 // This will be the "starts humongous" region.
633 HeapRegion* first_hr = region_at(first);
634 // The header of the new object will be placed at the bottom of
635 // the first region.
636 HeapWord* new_obj = first_hr->bottom();
637 // This will be the new end of the first region in the series that
638 // should also match the end of the last region in the series.
639 HeapWord* new_end = new_obj + word_size_sum;
640 // This will be the new top of the first region that will reflect
641 // this allocation.
642 HeapWord* new_top = new_obj + word_size;
643
644 // First, we need to zero the header of the space that we will be
645 // allocating. When we update top further down, some refinement
646 // threads might try to scan the region. By zeroing the header we
647 // ensure that any thread that will try to scan the region will
648 // come across the zero klass word and bail out.
649 //
650 // NOTE: It would not have been correct to have used
651 // CollectedHeap::fill_with_object() and make the space look like
652 // an int array. The thread that is doing the allocation will
653 // later update the object header to a potentially different array
654 // type and, for a very short period of time, the klass and length
655 // fields will be inconsistent. This could cause a refinement
656 // thread to calculate the object size incorrectly.
657 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
658
659 // We will set up the first region as "starts humongous". This
660 // will also update the BOT covering all the regions to reflect
661 // that there is a single object that starts at the bottom of the
662 // first region.
663 first_hr->set_startsHumongous(new_top, new_end);
664 first_hr->set_allocation_context(context);
665 // Then, if there are any, we will set up the "continues
666 // humongous" regions.
667 HeapRegion* hr = NULL;
668 for (uint i = first + 1; i < last; ++i) {
669 hr = region_at(i);
670 hr->set_continuesHumongous(first_hr);
671 hr->set_allocation_context(context);
672 }
673 // If we have "continues humongous" regions (hr != NULL), then the
674 // end of the last one should match new_end.
675 assert(hr == NULL || hr->end() == new_end, "sanity");
676
677 // Up to this point no concurrent thread would have been able to
678 // do any scanning on any region in this series. All the top
679 // fields still point to bottom, so the intersection between
680 // [bottom,top] and [card_start,card_end] will be empty. Before we
681 // update the top fields, we'll do a storestore to make sure that
682 // no thread sees the update to top before the zeroing of the
683 // object header and the BOT initialization.
684 OrderAccess::storestore();
685
686 // Now that the BOT and the object header have been initialized,
687 // we can update top of the "starts humongous" region.
688 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
689 "new_top should be in this region");
690 first_hr->set_top(new_top);
691 if (_hr_printer.is_active()) {
692 HeapWord* bottom = first_hr->bottom();
693 HeapWord* end = first_hr->orig_end();
694 if ((first + 1) == last) {
695 // the series has a single humongous region
696 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
697 } else {
698 // the series has more than one humongous regions
699 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
700 }
701 }
702
703 // Now, we will update the top fields of the "continues humongous"
704 // regions. The reason we need to do this is that, otherwise,
705 // these regions would look empty and this will confuse parts of
706 // G1. For example, the code that looks for a consecutive number
707 // of empty regions will consider them empty and try to
708 // re-allocate them. We can extend is_empty() to also include
709 // !continuesHumongous(), but it is easier to just update the top
710 // fields here. The way we set top for all regions (i.e., top ==
711 // end for all regions but the last one, top == new_top for the
712 // last one) is actually used when we will free up the humongous
713 // region in free_humongous_region().
714 hr = NULL;
715 for (uint i = first + 1; i < last; ++i) {
716 hr = region_at(i);
717 if ((i + 1) == last) {
718 // last continues humongous region
719 assert(hr->bottom() < new_top && new_top <= hr->end(),
720 "new_top should fall on this region");
721 hr->set_top(new_top);
722 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
723 } else {
724 // not last one
725 assert(new_top > hr->end(), "new_top should be above this region");
726 hr->set_top(hr->end());
727 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
728 }
729 }
730 // If we have continues humongous regions (hr != NULL), then the
731 // end of the last one should match new_end and its top should
732 // match new_top.
733 assert(hr == NULL ||
734 (hr->end() == new_end && hr->top() == new_top), "sanity");
735 check_bitmaps("Humongous Region Allocation", first_hr);
736
737 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
738 _allocator->increase_used(first_hr->used());
739 _humongous_set.add(first_hr);
740
741 return new_obj;
742 }
743
744 // If could fit into free regions w/o expansion, try.
745 // Otherwise, if can expand, do so.
746 // Otherwise, if using ex regions might help, try with ex given back.
747 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
748 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
749
750 verify_region_sets_optional();
751
752 uint first = G1_NO_HRM_INDEX;
753 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
754
755 if (obj_regions == 1) {
756 // Only one region to allocate, try to use a fast path by directly allocating
757 // from the free lists. Do not try to expand here, we will potentially do that
758 // later.
759 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
760 if (hr != NULL) {
761 first = hr->hrm_index();
762 }
763 } else {
764 // We can't allocate humongous regions spanning more than one region while
765 // cleanupComplete() is running, since some of the regions we find to be
766 // empty might not yet be added to the free list. It is not straightforward
767 // to know in which list they are on so that we can remove them. We only
768 // need to do this if we need to allocate more than one region to satisfy the
769 // current humongous allocation request. If we are only allocating one region
770 // we use the one-region region allocation code (see above), that already
771 // potentially waits for regions from the secondary free list.
772 wait_while_free_regions_coming();
773 append_secondary_free_list_if_not_empty_with_lock();
774
775 // Policy: Try only empty regions (i.e. already committed first). Maybe we
776 // are lucky enough to find some.
777 first = _hrm.find_contiguous_only_empty(obj_regions);
778 if (first != G1_NO_HRM_INDEX) {
779 _hrm.allocate_free_regions_starting_at(first, obj_regions);
780 }
781 }
782
783 if (first == G1_NO_HRM_INDEX) {
784 // Policy: We could not find enough regions for the humongous object in the
785 // free list. Look through the heap to find a mix of free and uncommitted regions.
786 // If so, try expansion.
787 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
788 if (first != G1_NO_HRM_INDEX) {
789 // We found something. Make sure these regions are committed, i.e. expand
790 // the heap. Alternatively we could do a defragmentation GC.
791 ergo_verbose1(ErgoHeapSizing,
792 "attempt heap expansion",
793 ergo_format_reason("humongous allocation request failed")
794 ergo_format_byte("allocation request"),
795 word_size * HeapWordSize);
796
797 _hrm.expand_at(first, obj_regions);
798 g1_policy()->record_new_heap_size(num_regions());
799
800 #ifdef ASSERT
801 for (uint i = first; i < first + obj_regions; ++i) {
802 HeapRegion* hr = region_at(i);
803 assert(hr->is_empty(), "sanity");
804 assert(is_on_master_free_list(hr), "sanity");
805 }
806 #endif
807 _hrm.allocate_free_regions_starting_at(first, obj_regions);
808 } else {
809 // Policy: Potentially trigger a defragmentation GC.
810 }
811 }
812
813 HeapWord* result = NULL;
814 if (first != G1_NO_HRM_INDEX) {
815 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
816 word_size, context);
817 assert(result != NULL, "it should always return a valid result");
818
819 // A successful humongous object allocation changes the used space
820 // information of the old generation so we need to recalculate the
821 // sizes and update the jstat counters here.
822 g1mm()->update_sizes();
823 }
824
825 verify_region_sets_optional();
826
827 return result;
828 }
829
830 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
831 assert_heap_not_locked_and_not_at_safepoint();
832 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
833
834 unsigned int dummy_gc_count_before;
835 int dummy_gclocker_retry_count = 0;
836 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
837 }
838
839 HeapWord*
840 G1CollectedHeap::mem_allocate(size_t word_size,
841 bool* gc_overhead_limit_was_exceeded) {
842 assert_heap_not_locked_and_not_at_safepoint();
843
844 // Loop until the allocation is satisfied, or unsatisfied after GC.
845 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
846 unsigned int gc_count_before;
847
848 HeapWord* result = NULL;
849 if (!isHumongous(word_size)) {
850 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
851 } else {
852 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
853 }
854 if (result != NULL) {
855 return result;
856 }
857
858 // Create the garbage collection operation...
859 VM_G1CollectForAllocation op(gc_count_before, word_size);
860 op.set_allocation_context(AllocationContext::current());
861
862 // ...and get the VM thread to execute it.
863 VMThread::execute(&op);
864
865 if (op.prologue_succeeded() && op.pause_succeeded()) {
866 // If the operation was successful we'll return the result even
867 // if it is NULL. If the allocation attempt failed immediately
868 // after a Full GC, it's unlikely we'll be able to allocate now.
869 HeapWord* result = op.result();
870 if (result != NULL && !isHumongous(word_size)) {
871 // Allocations that take place on VM operations do not do any
872 // card dirtying and we have to do it here. We only have to do
873 // this for non-humongous allocations, though.
874 dirty_young_block(result, word_size);
875 }
876 return result;
877 } else {
878 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
879 return NULL;
880 }
881 assert(op.result() == NULL,
882 "the result should be NULL if the VM op did not succeed");
883 }
884
885 // Give a warning if we seem to be looping forever.
886 if ((QueuedAllocationWarningCount > 0) &&
887 (try_count % QueuedAllocationWarningCount == 0)) {
888 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
889 }
890 }
891
892 ShouldNotReachHere();
893 return NULL;
894 }
895
896 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
897 AllocationContext_t context,
898 unsigned int *gc_count_before_ret,
899 int* gclocker_retry_count_ret) {
900 // Make sure you read the note in attempt_allocation_humongous().
901
902 assert_heap_not_locked_and_not_at_safepoint();
903 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
904 "be called for humongous allocation requests");
905
906 // We should only get here after the first-level allocation attempt
907 // (attempt_allocation()) failed to allocate.
908
909 // We will loop until a) we manage to successfully perform the
910 // allocation or b) we successfully schedule a collection which
911 // fails to perform the allocation. b) is the only case when we'll
912 // return NULL.
913 HeapWord* result = NULL;
914 for (int try_count = 1; /* we'll return */; try_count += 1) {
915 bool should_try_gc;
916 unsigned int gc_count_before;
917
918 {
919 MutexLockerEx x(Heap_lock);
920 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
921 false /* bot_updates */);
922 if (result != NULL) {
923 return result;
924 }
925
926 // If we reach here, attempt_allocation_locked() above failed to
927 // allocate a new region. So the mutator alloc region should be NULL.
928 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
929
930 if (GC_locker::is_active_and_needs_gc()) {
931 if (g1_policy()->can_expand_young_list()) {
932 // No need for an ergo verbose message here,
933 // can_expand_young_list() does this when it returns true.
934 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
935 false /* bot_updates */);
936 if (result != NULL) {
937 return result;
938 }
939 }
940 should_try_gc = false;
941 } else {
942 // The GCLocker may not be active but the GCLocker initiated
943 // GC may not yet have been performed (GCLocker::needs_gc()
944 // returns true). In this case we do not try this GC and
945 // wait until the GCLocker initiated GC is performed, and
946 // then retry the allocation.
947 if (GC_locker::needs_gc()) {
948 should_try_gc = false;
949 } else {
950 // Read the GC count while still holding the Heap_lock.
951 gc_count_before = total_collections();
952 should_try_gc = true;
953 }
954 }
955 }
956
957 if (should_try_gc) {
958 bool succeeded;
959 result = do_collection_pause(word_size, gc_count_before, &succeeded,
960 GCCause::_g1_inc_collection_pause);
961 if (result != NULL) {
962 assert(succeeded, "only way to get back a non-NULL result");
963 return result;
964 }
965
966 if (succeeded) {
967 // If we get here we successfully scheduled a collection which
968 // failed to allocate. No point in trying to allocate
969 // further. We'll just return NULL.
970 MutexLockerEx x(Heap_lock);
971 *gc_count_before_ret = total_collections();
972 return NULL;
973 }
974 } else {
975 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
976 MutexLockerEx x(Heap_lock);
977 *gc_count_before_ret = total_collections();
978 return NULL;
979 }
980 // The GCLocker is either active or the GCLocker initiated
981 // GC has not yet been performed. Stall until it is and
982 // then retry the allocation.
983 GC_locker::stall_until_clear();
984 (*gclocker_retry_count_ret) += 1;
985 }
986
987 // We can reach here if we were unsuccessful in scheduling a
988 // collection (because another thread beat us to it) or if we were
989 // stalled due to the GC locker. In either can we should retry the
990 // allocation attempt in case another thread successfully
991 // performed a collection and reclaimed enough space. We do the
992 // first attempt (without holding the Heap_lock) here and the
993 // follow-on attempt will be at the start of the next loop
994 // iteration (after taking the Heap_lock).
995 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
996 false /* bot_updates */);
997 if (result != NULL) {
998 return result;
999 }
1000
1001 // Give a warning if we seem to be looping forever.
1002 if ((QueuedAllocationWarningCount > 0) &&
1003 (try_count % QueuedAllocationWarningCount == 0)) {
1004 warning("G1CollectedHeap::attempt_allocation_slow() "
1005 "retries %d times", try_count);
1006 }
1007 }
1008
1009 ShouldNotReachHere();
1010 return NULL;
1011 }
1012
1013 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1014 unsigned int * gc_count_before_ret,
1015 int* gclocker_retry_count_ret) {
1016 // The structure of this method has a lot of similarities to
1017 // attempt_allocation_slow(). The reason these two were not merged
1018 // into a single one is that such a method would require several "if
1019 // allocation is not humongous do this, otherwise do that"
1020 // conditional paths which would obscure its flow. In fact, an early
1021 // version of this code did use a unified method which was harder to
1022 // follow and, as a result, it had subtle bugs that were hard to
1023 // track down. So keeping these two methods separate allows each to
1024 // be more readable. It will be good to keep these two in sync as
1025 // much as possible.
1026
1027 assert_heap_not_locked_and_not_at_safepoint();
1028 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1029 "should only be called for humongous allocations");
1030
1031 // Humongous objects can exhaust the heap quickly, so we should check if we
1032 // need to start a marking cycle at each humongous object allocation. We do
1033 // the check before we do the actual allocation. The reason for doing it
1034 // before the allocation is that we avoid having to keep track of the newly
1035 // allocated memory while we do a GC.
1036 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1037 word_size)) {
1038 collect(GCCause::_g1_humongous_allocation);
1039 }
1040
1041 // We will loop until a) we manage to successfully perform the
1042 // allocation or b) we successfully schedule a collection which
1043 // fails to perform the allocation. b) is the only case when we'll
1044 // return NULL.
1045 HeapWord* result = NULL;
1046 for (int try_count = 1; /* we'll return */; try_count += 1) {
1047 bool should_try_gc;
1048 unsigned int gc_count_before;
1049
1050 {
1051 MutexLockerEx x(Heap_lock);
1052
1053 // Given that humongous objects are not allocated in young
1054 // regions, we'll first try to do the allocation without doing a
1055 // collection hoping that there's enough space in the heap.
1056 result = humongous_obj_allocate(word_size, AllocationContext::current());
1057 if (result != NULL) {
1058 return result;
1059 }
1060
1061 if (GC_locker::is_active_and_needs_gc()) {
1062 should_try_gc = false;
1063 } else {
1064 // The GCLocker may not be active but the GCLocker initiated
1065 // GC may not yet have been performed (GCLocker::needs_gc()
1066 // returns true). In this case we do not try this GC and
1067 // wait until the GCLocker initiated GC is performed, and
1068 // then retry the allocation.
1069 if (GC_locker::needs_gc()) {
1070 should_try_gc = false;
1071 } else {
1072 // Read the GC count while still holding the Heap_lock.
1073 gc_count_before = total_collections();
1074 should_try_gc = true;
1075 }
1076 }
1077 }
1078
1079 if (should_try_gc) {
1080 // If we failed to allocate the humongous object, we should try to
1081 // do a collection pause (if we're allowed) in case it reclaims
1082 // enough space for the allocation to succeed after the pause.
1083
1084 bool succeeded;
1085 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1086 GCCause::_g1_humongous_allocation);
1087 if (result != NULL) {
1088 assert(succeeded, "only way to get back a non-NULL result");
1089 return result;
1090 }
1091
1092 if (succeeded) {
1093 // If we get here we successfully scheduled a collection which
1094 // failed to allocate. No point in trying to allocate
1095 // further. We'll just return NULL.
1096 MutexLockerEx x(Heap_lock);
1097 *gc_count_before_ret = total_collections();
1098 return NULL;
1099 }
1100 } else {
1101 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1102 MutexLockerEx x(Heap_lock);
1103 *gc_count_before_ret = total_collections();
1104 return NULL;
1105 }
1106 // The GCLocker is either active or the GCLocker initiated
1107 // GC has not yet been performed. Stall until it is and
1108 // then retry the allocation.
1109 GC_locker::stall_until_clear();
1110 (*gclocker_retry_count_ret) += 1;
1111 }
1112
1113 // We can reach here if we were unsuccessful in scheduling a
1114 // collection (because another thread beat us to it) or if we were
1115 // stalled due to the GC locker. In either can we should retry the
1116 // allocation attempt in case another thread successfully
1117 // performed a collection and reclaimed enough space. Give a
1118 // warning if we seem to be looping forever.
1119
1120 if ((QueuedAllocationWarningCount > 0) &&
1121 (try_count % QueuedAllocationWarningCount == 0)) {
1122 warning("G1CollectedHeap::attempt_allocation_humongous() "
1123 "retries %d times", try_count);
1124 }
1125 }
1126
1127 ShouldNotReachHere();
1128 return NULL;
1129 }
1130
1131 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1132 AllocationContext_t context,
1133 bool expect_null_mutator_alloc_region) {
1134 assert_at_safepoint(true /* should_be_vm_thread */);
1135 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1136 !expect_null_mutator_alloc_region,
1137 "the current alloc region was unexpectedly found to be non-NULL");
1138
1139 if (!isHumongous(word_size)) {
1140 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1141 false /* bot_updates */);
1142 } else {
1143 HeapWord* result = humongous_obj_allocate(word_size, context);
1144 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1145 g1_policy()->set_initiate_conc_mark_if_possible();
1146 }
1147 return result;
1148 }
1149
1150 ShouldNotReachHere();
1151 }
1152
1153 class PostMCRemSetClearClosure: public HeapRegionClosure {
1154 G1CollectedHeap* _g1h;
1155 ModRefBarrierSet* _mr_bs;
1156 public:
1157 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1158 _g1h(g1h), _mr_bs(mr_bs) {}
1159
1160 bool doHeapRegion(HeapRegion* r) {
1161 HeapRegionRemSet* hrrs = r->rem_set();
1162
1163 if (r->continuesHumongous()) {
1164 // We'll assert that the strong code root list and RSet is empty
1165 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1166 assert(hrrs->occupied() == 0, "RSet should be empty");
1167 return false;
1168 }
1169
1170 _g1h->reset_gc_time_stamps(r);
1171 hrrs->clear();
1172 // You might think here that we could clear just the cards
1173 // corresponding to the used region. But no: if we leave a dirty card
1174 // in a region we might allocate into, then it would prevent that card
1175 // from being enqueued, and cause it to be missed.
1176 // Re: the performance cost: we shouldn't be doing full GC anyway!
1177 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1178
1179 return false;
1180 }
1181 };
1182
1183 void G1CollectedHeap::clear_rsets_post_compaction() {
1184 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1185 heap_region_iterate(&rs_clear);
1186 }
1187
1188 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1189 G1CollectedHeap* _g1h;
1190 UpdateRSOopClosure _cl;
1191 int _worker_i;
1192 public:
1193 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1194 _cl(g1->g1_rem_set(), worker_i),
1195 _worker_i(worker_i),
1196 _g1h(g1)
1197 { }
1198
1199 bool doHeapRegion(HeapRegion* r) {
1200 if (!r->continuesHumongous()) {
1201 _cl.set_from(r);
1202 r->oop_iterate(&_cl);
1203 }
1204 return false;
1205 }
1206 };
1207
1208 class ParRebuildRSTask: public AbstractGangTask {
1209 G1CollectedHeap* _g1;
1210 public:
1211 ParRebuildRSTask(G1CollectedHeap* g1)
1212 : AbstractGangTask("ParRebuildRSTask"),
1213 _g1(g1)
1214 { }
1215
1216 void work(uint worker_id) {
1217 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1218 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1219 _g1->workers()->active_workers(),
1220 HeapRegion::RebuildRSClaimValue);
1221 }
1222 };
1223
1224 class PostCompactionPrinterClosure: public HeapRegionClosure {
1225 private:
1226 G1HRPrinter* _hr_printer;
1227 public:
1228 bool doHeapRegion(HeapRegion* hr) {
1229 assert(!hr->is_young(), "not expecting to find young regions");
1230 // We only generate output for non-empty regions.
1231 if (!hr->is_empty()) {
1232 if (!hr->isHumongous()) {
1233 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1234 } else if (hr->startsHumongous()) {
1235 if (hr->region_num() == 1) {
1236 // single humongous region
1237 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1238 } else {
1239 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1240 }
1241 } else {
1242 assert(hr->continuesHumongous(), "only way to get here");
1243 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1244 }
1245 }
1246 return false;
1247 }
1248
1249 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1250 : _hr_printer(hr_printer) { }
1251 };
1252
1253 void G1CollectedHeap::print_hrm_post_compaction() {
1254 PostCompactionPrinterClosure cl(hr_printer());
1255 heap_region_iterate(&cl);
1256 }
1257
1258 bool G1CollectedHeap::do_collection(bool explicit_gc,
1259 bool clear_all_soft_refs,
1260 size_t word_size) {
1261 assert_at_safepoint(true /* should_be_vm_thread */);
1262
1263 if (GC_locker::check_active_before_gc()) {
1264 return false;
1265 }
1266
1267 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1268 gc_timer->register_gc_start();
1269
1270 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1271 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1272
1273 SvcGCMarker sgcm(SvcGCMarker::FULL);
1274 ResourceMark rm;
1275
1276 print_heap_before_gc();
1277 trace_heap_before_gc(gc_tracer);
1278
1279 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1280
1281 verify_region_sets_optional();
1282
1283 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1284 collector_policy()->should_clear_all_soft_refs();
1285
1286 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1287
1288 {
1289 IsGCActiveMark x;
1290
1291 // Timing
1292 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1293 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1294 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1295
1296 {
1297 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1298 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1299 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1300
1301 double start = os::elapsedTime();
1302 g1_policy()->record_full_collection_start();
1303
1304 // Note: When we have a more flexible GC logging framework that
1305 // allows us to add optional attributes to a GC log record we
1306 // could consider timing and reporting how long we wait in the
1307 // following two methods.
1308 wait_while_free_regions_coming();
1309 // If we start the compaction before the CM threads finish
1310 // scanning the root regions we might trip them over as we'll
1311 // be moving objects / updating references. So let's wait until
1312 // they are done. By telling them to abort, they should complete
1313 // early.
1314 _cm->root_regions()->abort();
1315 _cm->root_regions()->wait_until_scan_finished();
1316 append_secondary_free_list_if_not_empty_with_lock();
1317
1318 gc_prologue(true);
1319 increment_total_collections(true /* full gc */);
1320 increment_old_marking_cycles_started();
1321
1322 assert(used() == recalculate_used(), "Should be equal");
1323
1324 verify_before_gc();
1325
1326 check_bitmaps("Full GC Start");
1327 pre_full_gc_dump(gc_timer);
1328
1329 COMPILER2_PRESENT(DerivedPointerTable::clear());
1330
1331 // Disable discovery and empty the discovered lists
1332 // for the CM ref processor.
1333 ref_processor_cm()->disable_discovery();
1334 ref_processor_cm()->abandon_partial_discovery();
1335 ref_processor_cm()->verify_no_references_recorded();
1336
1337 // Abandon current iterations of concurrent marking and concurrent
1338 // refinement, if any are in progress. We have to do this before
1339 // wait_until_scan_finished() below.
1340 concurrent_mark()->abort();
1341
1342 // Make sure we'll choose a new allocation region afterwards.
1343 _allocator->release_mutator_alloc_region();
1344 _allocator->abandon_gc_alloc_regions();
1345 g1_rem_set()->cleanupHRRS();
1346
1347 // We should call this after we retire any currently active alloc
1348 // regions so that all the ALLOC / RETIRE events are generated
1349 // before the start GC event.
1350 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1351
1352 // We may have added regions to the current incremental collection
1353 // set between the last GC or pause and now. We need to clear the
1354 // incremental collection set and then start rebuilding it afresh
1355 // after this full GC.
1356 abandon_collection_set(g1_policy()->inc_cset_head());
1357 g1_policy()->clear_incremental_cset();
1358 g1_policy()->stop_incremental_cset_building();
1359
1360 tear_down_region_sets(false /* free_list_only */);
1361 g1_policy()->set_gcs_are_young(true);
1362
1363 // See the comments in g1CollectedHeap.hpp and
1364 // G1CollectedHeap::ref_processing_init() about
1365 // how reference processing currently works in G1.
1366
1367 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1368 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1369
1370 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1371 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1372
1373 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1374 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1375
1376 // Do collection work
1377 {
1378 HandleMark hm; // Discard invalid handles created during gc
1379 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1380 }
1381
1382 assert(num_free_regions() == 0, "we should not have added any free regions");
1383 rebuild_region_sets(false /* free_list_only */);
1384
1385 // Enqueue any discovered reference objects that have
1386 // not been removed from the discovered lists.
1387 ref_processor_stw()->enqueue_discovered_references();
1388
1389 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1390
1391 MemoryService::track_memory_usage();
1392
1393 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1394 ref_processor_stw()->verify_no_references_recorded();
1395
1396 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1397 ClassLoaderDataGraph::purge();
1398 MetaspaceAux::verify_metrics();
1399
1400 // Note: since we've just done a full GC, concurrent
1401 // marking is no longer active. Therefore we need not
1402 // re-enable reference discovery for the CM ref processor.
1403 // That will be done at the start of the next marking cycle.
1404 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1405 ref_processor_cm()->verify_no_references_recorded();
1406
1407 reset_gc_time_stamp();
1408 // Since everything potentially moved, we will clear all remembered
1409 // sets, and clear all cards. Later we will rebuild remembered
1410 // sets. We will also reset the GC time stamps of the regions.
1411 clear_rsets_post_compaction();
1412 check_gc_time_stamps();
1413
1414 // Resize the heap if necessary.
1415 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1416
1417 if (_hr_printer.is_active()) {
1418 // We should do this after we potentially resize the heap so
1419 // that all the COMMIT / UNCOMMIT events are generated before
1420 // the end GC event.
1421
1422 print_hrm_post_compaction();
1423 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1424 }
1425
1426 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1427 if (hot_card_cache->use_cache()) {
1428 hot_card_cache->reset_card_counts();
1429 hot_card_cache->reset_hot_cache();
1430 }
1431
1432 // Rebuild remembered sets of all regions.
1433 if (G1CollectedHeap::use_parallel_gc_threads()) {
1434 uint n_workers =
1435 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1436 workers()->active_workers(),
1437 Threads::number_of_non_daemon_threads());
1438 assert(UseDynamicNumberOfGCThreads ||
1439 n_workers == workers()->total_workers(),
1440 "If not dynamic should be using all the workers");
1441 workers()->set_active_workers(n_workers);
1442 // Set parallel threads in the heap (_n_par_threads) only
1443 // before a parallel phase and always reset it to 0 after
1444 // the phase so that the number of parallel threads does
1445 // no get carried forward to a serial phase where there
1446 // may be code that is "possibly_parallel".
1447 set_par_threads(n_workers);
1448
1449 ParRebuildRSTask rebuild_rs_task(this);
1450 assert(check_heap_region_claim_values(
1451 HeapRegion::InitialClaimValue), "sanity check");
1452 assert(UseDynamicNumberOfGCThreads ||
1453 workers()->active_workers() == workers()->total_workers(),
1454 "Unless dynamic should use total workers");
1455 // Use the most recent number of active workers
1456 assert(workers()->active_workers() > 0,
1457 "Active workers not properly set");
1458 set_par_threads(workers()->active_workers());
1459 workers()->run_task(&rebuild_rs_task);
1460 set_par_threads(0);
1461 assert(check_heap_region_claim_values(
1462 HeapRegion::RebuildRSClaimValue), "sanity check");
1463 reset_heap_region_claim_values();
1464 } else {
1465 RebuildRSOutOfRegionClosure rebuild_rs(this);
1466 heap_region_iterate(&rebuild_rs);
1467 }
1468
1469 // Rebuild the strong code root lists for each region
1470 rebuild_strong_code_roots();
1471
1472 if (true) { // FIXME
1473 MetaspaceGC::compute_new_size();
1474 }
1475
1476 #ifdef TRACESPINNING
1477 ParallelTaskTerminator::print_termination_counts();
1478 #endif
1479
1480 // Discard all rset updates
1481 JavaThread::dirty_card_queue_set().abandon_logs();
1482 assert(!G1DeferredRSUpdate
1483 || (G1DeferredRSUpdate &&
1484 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1485
1486 _young_list->reset_sampled_info();
1487 // At this point there should be no regions in the
1488 // entire heap tagged as young.
1489 assert(check_young_list_empty(true /* check_heap */),
1490 "young list should be empty at this point");
1491
1492 // Update the number of full collections that have been completed.
1493 increment_old_marking_cycles_completed(false /* concurrent */);
1494
1495 _hrm.verify_optional();
1496 verify_region_sets_optional();
1497
1498 verify_after_gc();
1499
1500 // Clear the previous marking bitmap, if needed for bitmap verification.
1501 // Note we cannot do this when we clear the next marking bitmap in
1502 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1503 // objects marked during a full GC against the previous bitmap.
1504 // But we need to clear it before calling check_bitmaps below since
1505 // the full GC has compacted objects and updated TAMS but not updated
1506 // the prev bitmap.
1507 if (G1VerifyBitmaps) {
1508 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1509 }
1510 check_bitmaps("Full GC End");
1511
1512 // Start a new incremental collection set for the next pause
1513 assert(g1_policy()->collection_set() == NULL, "must be");
1514 g1_policy()->start_incremental_cset_building();
1515
1516 clear_cset_fast_test();
1517
1518 _allocator->init_mutator_alloc_region();
1519
1520 double end = os::elapsedTime();
1521 g1_policy()->record_full_collection_end();
1522
1523 if (G1Log::fine()) {
1524 g1_policy()->print_heap_transition();
1525 }
1526
1527 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1528 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1529 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1530 // before any GC notifications are raised.
1531 g1mm()->update_sizes();
1532
1533 gc_epilogue(true);
1534 }
1535
1536 if (G1Log::finer()) {
1537 g1_policy()->print_detailed_heap_transition(true /* full */);
1538 }
1539
1540 print_heap_after_gc();
1541 trace_heap_after_gc(gc_tracer);
1542
1543 post_full_gc_dump(gc_timer);
1544
1545 gc_timer->register_gc_end();
1546 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1547 }
1548
1549 return true;
1550 }
1551
1552 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1553 // do_collection() will return whether it succeeded in performing
1554 // the GC. Currently, there is no facility on the
1555 // do_full_collection() API to notify the caller than the collection
1556 // did not succeed (e.g., because it was locked out by the GC
1557 // locker). So, right now, we'll ignore the return value.
1558 bool dummy = do_collection(true, /* explicit_gc */
1559 clear_all_soft_refs,
1560 0 /* word_size */);
1561 }
1562
1563 // This code is mostly copied from TenuredGeneration.
1564 void
1565 G1CollectedHeap::
1566 resize_if_necessary_after_full_collection(size_t word_size) {
1567 // Include the current allocation, if any, and bytes that will be
1568 // pre-allocated to support collections, as "used".
1569 const size_t used_after_gc = used();
1570 const size_t capacity_after_gc = capacity();
1571 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1572
1573 // This is enforced in arguments.cpp.
1574 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1575 "otherwise the code below doesn't make sense");
1576
1577 // We don't have floating point command-line arguments
1578 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1579 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1580 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1581 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1582
1583 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1584 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1585
1586 // We have to be careful here as these two calculations can overflow
1587 // 32-bit size_t's.
1588 double used_after_gc_d = (double) used_after_gc;
1589 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1590 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1591
1592 // Let's make sure that they are both under the max heap size, which
1593 // by default will make them fit into a size_t.
1594 double desired_capacity_upper_bound = (double) max_heap_size;
1595 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1596 desired_capacity_upper_bound);
1597 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1598 desired_capacity_upper_bound);
1599
1600 // We can now safely turn them into size_t's.
1601 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1602 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1603
1604 // This assert only makes sense here, before we adjust them
1605 // with respect to the min and max heap size.
1606 assert(minimum_desired_capacity <= maximum_desired_capacity,
1607 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1608 "maximum_desired_capacity = "SIZE_FORMAT,
1609 minimum_desired_capacity, maximum_desired_capacity));
1610
1611 // Should not be greater than the heap max size. No need to adjust
1612 // it with respect to the heap min size as it's a lower bound (i.e.,
1613 // we'll try to make the capacity larger than it, not smaller).
1614 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1615 // Should not be less than the heap min size. No need to adjust it
1616 // with respect to the heap max size as it's an upper bound (i.e.,
1617 // we'll try to make the capacity smaller than it, not greater).
1618 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1619
1620 if (capacity_after_gc < minimum_desired_capacity) {
1621 // Don't expand unless it's significant
1622 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1623 ergo_verbose4(ErgoHeapSizing,
1624 "attempt heap expansion",
1625 ergo_format_reason("capacity lower than "
1626 "min desired capacity after Full GC")
1627 ergo_format_byte("capacity")
1628 ergo_format_byte("occupancy")
1629 ergo_format_byte_perc("min desired capacity"),
1630 capacity_after_gc, used_after_gc,
1631 minimum_desired_capacity, (double) MinHeapFreeRatio);
1632 expand(expand_bytes);
1633
1634 // No expansion, now see if we want to shrink
1635 } else if (capacity_after_gc > maximum_desired_capacity) {
1636 // Capacity too large, compute shrinking size
1637 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1638 ergo_verbose4(ErgoHeapSizing,
1639 "attempt heap shrinking",
1640 ergo_format_reason("capacity higher than "
1641 "max desired capacity after Full GC")
1642 ergo_format_byte("capacity")
1643 ergo_format_byte("occupancy")
1644 ergo_format_byte_perc("max desired capacity"),
1645 capacity_after_gc, used_after_gc,
1646 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1647 shrink(shrink_bytes);
1648 }
1649 }
1650
1651
1652 HeapWord*
1653 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1654 AllocationContext_t context,
1655 bool* succeeded) {
1656 assert_at_safepoint(true /* should_be_vm_thread */);
1657
1658 *succeeded = true;
1659 // Let's attempt the allocation first.
1660 HeapWord* result =
1661 attempt_allocation_at_safepoint(word_size,
1662 context,
1663 false /* expect_null_mutator_alloc_region */);
1664 if (result != NULL) {
1665 assert(*succeeded, "sanity");
1666 return result;
1667 }
1668
1669 // In a G1 heap, we're supposed to keep allocation from failing by
1670 // incremental pauses. Therefore, at least for now, we'll favor
1671 // expansion over collection. (This might change in the future if we can
1672 // do something smarter than full collection to satisfy a failed alloc.)
1673 result = expand_and_allocate(word_size, context);
1674 if (result != NULL) {
1675 assert(*succeeded, "sanity");
1676 return result;
1677 }
1678
1679 // Expansion didn't work, we'll try to do a Full GC.
1680 bool gc_succeeded = do_collection(false, /* explicit_gc */
1681 false, /* clear_all_soft_refs */
1682 word_size);
1683 if (!gc_succeeded) {
1684 *succeeded = false;
1685 return NULL;
1686 }
1687
1688 // Retry the allocation
1689 result = attempt_allocation_at_safepoint(word_size,
1690 context,
1691 true /* expect_null_mutator_alloc_region */);
1692 if (result != NULL) {
1693 assert(*succeeded, "sanity");
1694 return result;
1695 }
1696
1697 // Then, try a Full GC that will collect all soft references.
1698 gc_succeeded = do_collection(false, /* explicit_gc */
1699 true, /* clear_all_soft_refs */
1700 word_size);
1701 if (!gc_succeeded) {
1702 *succeeded = false;
1703 return NULL;
1704 }
1705
1706 // Retry the allocation once more
1707 result = attempt_allocation_at_safepoint(word_size,
1708 context,
1709 true /* expect_null_mutator_alloc_region */);
1710 if (result != NULL) {
1711 assert(*succeeded, "sanity");
1712 return result;
1713 }
1714
1715 assert(!collector_policy()->should_clear_all_soft_refs(),
1716 "Flag should have been handled and cleared prior to this point");
1717
1718 // What else? We might try synchronous finalization later. If the total
1719 // space available is large enough for the allocation, then a more
1720 // complete compaction phase than we've tried so far might be
1721 // appropriate.
1722 assert(*succeeded, "sanity");
1723 return NULL;
1724 }
1725
1726 // Attempting to expand the heap sufficiently
1727 // to support an allocation of the given "word_size". If
1728 // successful, perform the allocation and return the address of the
1729 // allocated block, or else "NULL".
1730
1731 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1732 assert_at_safepoint(true /* should_be_vm_thread */);
1733
1734 verify_region_sets_optional();
1735
1736 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1737 ergo_verbose1(ErgoHeapSizing,
1738 "attempt heap expansion",
1739 ergo_format_reason("allocation request failed")
1740 ergo_format_byte("allocation request"),
1741 word_size * HeapWordSize);
1742 if (expand(expand_bytes)) {
1743 _hrm.verify_optional();
1744 verify_region_sets_optional();
1745 return attempt_allocation_at_safepoint(word_size,
1746 context,
1747 false /* expect_null_mutator_alloc_region */);
1748 }
1749 return NULL;
1750 }
1751
1752 bool G1CollectedHeap::expand(size_t expand_bytes) {
1753 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1754 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1755 HeapRegion::GrainBytes);
1756 ergo_verbose2(ErgoHeapSizing,
1757 "expand the heap",
1758 ergo_format_byte("requested expansion amount")
1759 ergo_format_byte("attempted expansion amount"),
1760 expand_bytes, aligned_expand_bytes);
1761
1762 if (is_maximal_no_gc()) {
1763 ergo_verbose0(ErgoHeapSizing,
1764 "did not expand the heap",
1765 ergo_format_reason("heap already fully expanded"));
1766 return false;
1767 }
1768
1769 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1770 assert(regions_to_expand > 0, "Must expand by at least one region");
1771
1772 uint expanded_by = _hrm.expand_by(regions_to_expand);
1773
1774 if (expanded_by > 0) {
1775 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1776 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1777 g1_policy()->record_new_heap_size(num_regions());
1778 } else {
1779 ergo_verbose0(ErgoHeapSizing,
1780 "did not expand the heap",
1781 ergo_format_reason("heap expansion operation failed"));
1782 // The expansion of the virtual storage space was unsuccessful.
1783 // Let's see if it was because we ran out of swap.
1784 if (G1ExitOnExpansionFailure &&
1785 _hrm.available() >= regions_to_expand) {
1786 // We had head room...
1787 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1788 }
1789 }
1790 return regions_to_expand > 0;
1791 }
1792
1793 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1794 size_t aligned_shrink_bytes =
1795 ReservedSpace::page_align_size_down(shrink_bytes);
1796 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1797 HeapRegion::GrainBytes);
1798 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1799
1800 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1801 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1802
1803 ergo_verbose3(ErgoHeapSizing,
1804 "shrink the heap",
1805 ergo_format_byte("requested shrinking amount")
1806 ergo_format_byte("aligned shrinking amount")
1807 ergo_format_byte("attempted shrinking amount"),
1808 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1809 if (num_regions_removed > 0) {
1810 g1_policy()->record_new_heap_size(num_regions());
1811 } else {
1812 ergo_verbose0(ErgoHeapSizing,
1813 "did not shrink the heap",
1814 ergo_format_reason("heap shrinking operation failed"));
1815 }
1816 }
1817
1818 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1819 verify_region_sets_optional();
1820
1821 // We should only reach here at the end of a Full GC which means we
1822 // should not not be holding to any GC alloc regions. The method
1823 // below will make sure of that and do any remaining clean up.
1824 _allocator->abandon_gc_alloc_regions();
1825
1826 // Instead of tearing down / rebuilding the free lists here, we
1827 // could instead use the remove_all_pending() method on free_list to
1828 // remove only the ones that we need to remove.
1829 tear_down_region_sets(true /* free_list_only */);
1830 shrink_helper(shrink_bytes);
1831 rebuild_region_sets(true /* free_list_only */);
1832
1833 _hrm.verify_optional();
1834 verify_region_sets_optional();
1835 }
1836
1837 // Public methods.
1838
1839 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1840 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1841 #endif // _MSC_VER
1842
1843
1844 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1845 SharedHeap(policy_),
1846 _g1_policy(policy_),
1847 _dirty_card_queue_set(false),
1848 _into_cset_dirty_card_queue_set(false),
1849 _is_alive_closure_cm(this),
1850 _is_alive_closure_stw(this),
1851 _ref_processor_cm(NULL),
1852 _ref_processor_stw(NULL),
1853 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1854 _bot_shared(NULL),
1855 _evac_failure_scan_stack(NULL),
1856 _mark_in_progress(false),
1857 _cg1r(NULL),
1858 _g1mm(NULL),
1859 _refine_cte_cl(NULL),
1860 _full_collection(false),
1861 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1862 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1863 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1864 _humongous_is_live(),
1865 _has_humongous_reclaim_candidates(false),
1866 _free_regions_coming(false),
1867 _young_list(new YoungList(this)),
1868 _gc_time_stamp(0),
1869 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1870 _old_plab_stats(OldPLABSize, PLABWeight),
1871 _expand_heap_after_alloc_failure(true),
1872 _surviving_young_words(NULL),
1873 _old_marking_cycles_started(0),
1874 _old_marking_cycles_completed(0),
1875 _concurrent_cycle_started(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 // It is important to do this in a way such that concurrent readers can't
1968 // temporarily think something is in the heap. (I've actually seen this
1969 // happen in asserts: DLD.)
1970 _reserved.set_word_size(0);
1971 _reserved.set_start((HeapWord*)heap_rs.base());
1972 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1973
1974 // Create the gen rem set (and barrier set) for the entire reserved region.
1975 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1976 set_barrier_set(rem_set()->bs());
1977 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1978 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1979 return JNI_ENOMEM;
1980 }
1981
1982 // Also create a G1 rem set.
1983 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1984
1985 // Carve out the G1 part of the heap.
1986
1987 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1988 G1RegionToSpaceMapper* heap_storage =
1989 G1RegionToSpaceMapper::create_mapper(g1_rs,
1990 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1991 HeapRegion::GrainBytes,
1992 1,
1993 mtJavaHeap);
1994 heap_storage->set_mapping_changed_listener(&_listener);
1995
1996 // Reserve space for the block offset table. We do not support automatic uncommit
1997 // for the card table at this time. BOT only.
1998 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1999 G1RegionToSpaceMapper* bot_storage =
2000 G1RegionToSpaceMapper::create_mapper(bot_rs,
2001 os::vm_page_size(),
2002 HeapRegion::GrainBytes,
2003 G1BlockOffsetSharedArray::N_bytes,
2004 mtGC);
2005
2006 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2007 G1RegionToSpaceMapper* cardtable_storage =
2008 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
2009 os::vm_page_size(),
2010 HeapRegion::GrainBytes,
2011 G1BlockOffsetSharedArray::N_bytes,
2012 mtGC);
2013
2014 // Reserve space for the card counts table.
2015 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
2016 G1RegionToSpaceMapper* card_counts_storage =
2017 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
2018 os::vm_page_size(),
2019 HeapRegion::GrainBytes,
2020 G1BlockOffsetSharedArray::N_bytes,
2021 mtGC);
2022
2023 // Reserve space for prev and next bitmap.
2024 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2025
2026 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2027 G1RegionToSpaceMapper* prev_bitmap_storage =
2028 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
2029 os::vm_page_size(),
2030 HeapRegion::GrainBytes,
2031 CMBitMap::mark_distance(),
2032 mtGC);
2033
2034 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
2035 G1RegionToSpaceMapper* next_bitmap_storage =
2036 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
2037 os::vm_page_size(),
2038 HeapRegion::GrainBytes,
2039 CMBitMap::mark_distance(),
2040 mtGC);
2041
2042 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2043 g1_barrier_set()->initialize(cardtable_storage);
2044 // Do later initialization work for concurrent refinement.
2045 _cg1r->init(card_counts_storage);
2046
2047 // 6843694 - ensure that the maximum region index can fit
2048 // in the remembered set structures.
2049 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2050 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2051
2052 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2053 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2054 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2055 "too many cards per region");
2056
2057 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2058
2059 _bot_shared = new G1BlockOffsetSharedArray(_reserved, bot_storage);
2060
2061 _g1h = this;
2062
2063 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2064 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
2065
2066 // Create the ConcurrentMark data structure and thread.
2067 // (Must do this late, so that "max_regions" is defined.)
2068 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2069 if (_cm == NULL || !_cm->completed_initialization()) {
2070 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2071 return JNI_ENOMEM;
2072 }
2073 _cmThread = _cm->cmThread();
2074
2075 // Initialize the from_card cache structure of HeapRegionRemSet.
2076 HeapRegionRemSet::init_heap(max_regions());
2077
2078 // Now expand into the initial heap size.
2079 if (!expand(init_byte_size)) {
2080 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2081 return JNI_ENOMEM;
2082 }
2083
2084 // Perform any initialization actions delegated to the policy.
2085 g1_policy()->init();
2086
2087 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2088 SATB_Q_FL_lock,
2089 G1SATBProcessCompletedThreshold,
2090 Shared_SATB_Q_lock);
2091
2092 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2093 DirtyCardQ_CBL_mon,
2094 DirtyCardQ_FL_lock,
2095 concurrent_g1_refine()->yellow_zone(),
2096 concurrent_g1_refine()->red_zone(),
2097 Shared_DirtyCardQ_lock);
2098
2099 if (G1DeferredRSUpdate) {
2100 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2101 DirtyCardQ_CBL_mon,
2102 DirtyCardQ_FL_lock,
2103 -1, // never trigger processing
2104 -1, // no limit on length
2105 Shared_DirtyCardQ_lock,
2106 &JavaThread::dirty_card_queue_set());
2107 }
2108
2109 // Initialize the card queue set used to hold cards containing
2110 // references into the collection set.
2111 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2112 DirtyCardQ_CBL_mon,
2113 DirtyCardQ_FL_lock,
2114 -1, // never trigger processing
2115 -1, // no limit on length
2116 Shared_DirtyCardQ_lock,
2117 &JavaThread::dirty_card_queue_set());
2118
2119 // In case we're keeping closure specialization stats, initialize those
2120 // counts and that mechanism.
2121 SpecializationStats::clear();
2122
2123 // Here we allocate the dummy HeapRegion that is required by the
2124 // G1AllocRegion class.
2125 HeapRegion* dummy_region = _hrm.get_dummy_region();
2126
2127 // We'll re-use the same region whether the alloc region will
2128 // require BOT updates or not and, if it doesn't, then a non-young
2129 // region will complain that it cannot support allocations without
2130 // BOT updates. So we'll tag the dummy region as young to avoid that.
2131 dummy_region->set_young();
2132 // Make sure it's full.
2133 dummy_region->set_top(dummy_region->end());
2134 G1AllocRegion::setup(this, dummy_region);
2135
2136 _allocator->init_mutator_alloc_region();
2137
2138 // Do create of the monitoring and management support so that
2139 // values in the heap have been properly initialized.
2140 _g1mm = new G1MonitoringSupport(this);
2141
2142 G1StringDedup::initialize();
2143
2144 return JNI_OK;
2145 }
2146
2147 void G1CollectedHeap::stop() {
2148 // Stop all concurrent threads. We do this to make sure these threads
2149 // do not continue to execute and access resources (e.g. gclog_or_tty)
2150 // that are destroyed during shutdown.
2151 _cg1r->stop();
2152 _cmThread->stop();
2153 if (G1StringDedup::is_enabled()) {
2154 G1StringDedup::stop();
2155 }
2156 }
2157
2158 void G1CollectedHeap::clear_humongous_is_live_table() {
2159 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2160 _humongous_is_live.clear();
2161 }
2162
2163 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2164 return HeapRegion::max_region_size();
2165 }
2166
2167 void G1CollectedHeap::ref_processing_init() {
2168 // Reference processing in G1 currently works as follows:
2169 //
2170 // * There are two reference processor instances. One is
2171 // used to record and process discovered references
2172 // during concurrent marking; the other is used to
2173 // record and process references during STW pauses
2174 // (both full and incremental).
2175 // * Both ref processors need to 'span' the entire heap as
2176 // the regions in the collection set may be dotted around.
2177 //
2178 // * For the concurrent marking ref processor:
2179 // * Reference discovery is enabled at initial marking.
2180 // * Reference discovery is disabled and the discovered
2181 // references processed etc during remarking.
2182 // * Reference discovery is MT (see below).
2183 // * Reference discovery requires a barrier (see below).
2184 // * Reference processing may or may not be MT
2185 // (depending on the value of ParallelRefProcEnabled
2186 // and ParallelGCThreads).
2187 // * A full GC disables reference discovery by the CM
2188 // ref processor and abandons any entries on it's
2189 // discovered lists.
2190 //
2191 // * For the STW processor:
2192 // * Non MT discovery is enabled at the start of a full GC.
2193 // * Processing and enqueueing during a full GC is non-MT.
2194 // * During a full GC, references are processed after marking.
2195 //
2196 // * Discovery (may or may not be MT) is enabled at the start
2197 // of an incremental evacuation pause.
2198 // * References are processed near the end of a STW evacuation pause.
2199 // * For both types of GC:
2200 // * Discovery is atomic - i.e. not concurrent.
2201 // * Reference discovery will not need a barrier.
2202
2203 SharedHeap::ref_processing_init();
2204 MemRegion mr = reserved_region();
2205
2206 // Concurrent Mark ref processor
2207 _ref_processor_cm =
2208 new ReferenceProcessor(mr, // span
2209 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2210 // mt processing
2211 (int) ParallelGCThreads,
2212 // degree of mt processing
2213 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2214 // mt discovery
2215 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2216 // degree of mt discovery
2217 false,
2218 // Reference discovery is not atomic
2219 &_is_alive_closure_cm);
2220 // is alive closure
2221 // (for efficiency/performance)
2222
2223 // STW ref processor
2224 _ref_processor_stw =
2225 new ReferenceProcessor(mr, // span
2226 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2227 // mt processing
2228 MAX2((int)ParallelGCThreads, 1),
2229 // degree of mt processing
2230 (ParallelGCThreads > 1),
2231 // mt discovery
2232 MAX2((int)ParallelGCThreads, 1),
2233 // degree of mt discovery
2234 true,
2235 // Reference discovery is atomic
2236 &_is_alive_closure_stw);
2237 // is alive closure
2238 // (for efficiency/performance)
2239 }
2240
2241 size_t G1CollectedHeap::capacity() const {
2242 return _hrm.length() * HeapRegion::GrainBytes;
2243 }
2244
2245 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2246 assert(!hr->continuesHumongous(), "pre-condition");
2247 hr->reset_gc_time_stamp();
2248 if (hr->startsHumongous()) {
2249 uint first_index = hr->hrm_index() + 1;
2250 uint last_index = hr->last_hc_index();
2251 for (uint i = first_index; i < last_index; i += 1) {
2252 HeapRegion* chr = region_at(i);
2253 assert(chr->continuesHumongous(), "sanity");
2254 chr->reset_gc_time_stamp();
2255 }
2256 }
2257 }
2258
2259 #ifndef PRODUCT
2260 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2261 private:
2262 unsigned _gc_time_stamp;
2263 bool _failures;
2264
2265 public:
2266 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2267 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2268
2269 virtual bool doHeapRegion(HeapRegion* hr) {
2270 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2271 if (_gc_time_stamp != region_gc_time_stamp) {
2272 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2273 "expected %d", HR_FORMAT_PARAMS(hr),
2274 region_gc_time_stamp, _gc_time_stamp);
2275 _failures = true;
2276 }
2277 return false;
2278 }
2279
2280 bool failures() { return _failures; }
2281 };
2282
2283 void G1CollectedHeap::check_gc_time_stamps() {
2284 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2285 heap_region_iterate(&cl);
2286 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2287 }
2288 #endif // PRODUCT
2289
2290 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2291 DirtyCardQueue* into_cset_dcq,
2292 bool concurrent,
2293 uint worker_i) {
2294 // Clean cards in the hot card cache
2295 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2296 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2297
2298 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2299 int n_completed_buffers = 0;
2300 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2301 n_completed_buffers++;
2302 }
2303 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2304 dcqs.clear_n_completed_buffers();
2305 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2306 }
2307
2308
2309 // Computes the sum of the storage used by the various regions.
2310 size_t G1CollectedHeap::used() const {
2311 return _allocator->used();
2312 }
2313
2314 size_t G1CollectedHeap::used_unlocked() const {
2315 return _allocator->used_unlocked();
2316 }
2317
2318 class SumUsedClosure: public HeapRegionClosure {
2319 size_t _used;
2320 public:
2321 SumUsedClosure() : _used(0) {}
2322 bool doHeapRegion(HeapRegion* r) {
2323 if (!r->continuesHumongous()) {
2324 _used += r->used();
2325 }
2326 return false;
2327 }
2328 size_t result() { return _used; }
2329 };
2330
2331 size_t G1CollectedHeap::recalculate_used() const {
2332 double recalculate_used_start = os::elapsedTime();
2333
2334 SumUsedClosure blk;
2335 heap_region_iterate(&blk);
2336
2337 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2338 return blk.result();
2339 }
2340
2341 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2342 switch (cause) {
2343 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2344 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2345 case GCCause::_g1_humongous_allocation: return true;
2346 default: return false;
2347 }
2348 }
2349
2350 #ifndef PRODUCT
2351 void G1CollectedHeap::allocate_dummy_regions() {
2352 // Let's fill up most of the region
2353 size_t word_size = HeapRegion::GrainWords - 1024;
2354 // And as a result the region we'll allocate will be humongous.
2355 guarantee(isHumongous(word_size), "sanity");
2356
2357 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2358 // Let's use the existing mechanism for the allocation
2359 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2360 AllocationContext::system());
2361 if (dummy_obj != NULL) {
2362 MemRegion mr(dummy_obj, word_size);
2363 CollectedHeap::fill_with_object(mr);
2364 } else {
2365 // If we can't allocate once, we probably cannot allocate
2366 // again. Let's get out of the loop.
2367 break;
2368 }
2369 }
2370 }
2371 #endif // !PRODUCT
2372
2373 void G1CollectedHeap::increment_old_marking_cycles_started() {
2374 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2375 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2376 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2377 _old_marking_cycles_started, _old_marking_cycles_completed));
2378
2379 _old_marking_cycles_started++;
2380 }
2381
2382 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2383 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2384
2385 // We assume that if concurrent == true, then the caller is a
2386 // concurrent thread that was joined the Suspendible Thread
2387 // Set. If there's ever a cheap way to check this, we should add an
2388 // assert here.
2389
2390 // Given that this method is called at the end of a Full GC or of a
2391 // concurrent cycle, and those can be nested (i.e., a Full GC can
2392 // interrupt a concurrent cycle), the number of full collections
2393 // completed should be either one (in the case where there was no
2394 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2395 // behind the number of full collections started.
2396
2397 // This is the case for the inner caller, i.e. a Full GC.
2398 assert(concurrent ||
2399 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2400 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2401 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2402 "is inconsistent with _old_marking_cycles_completed = %u",
2403 _old_marking_cycles_started, _old_marking_cycles_completed));
2404
2405 // This is the case for the outer caller, i.e. the concurrent cycle.
2406 assert(!concurrent ||
2407 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2408 err_msg("for outer caller (concurrent cycle): "
2409 "_old_marking_cycles_started = %u "
2410 "is inconsistent with _old_marking_cycles_completed = %u",
2411 _old_marking_cycles_started, _old_marking_cycles_completed));
2412
2413 _old_marking_cycles_completed += 1;
2414
2415 // We need to clear the "in_progress" flag in the CM thread before
2416 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2417 // is set) so that if a waiter requests another System.gc() it doesn't
2418 // incorrectly see that a marking cycle is still in progress.
2419 if (concurrent) {
2420 _cmThread->clear_in_progress();
2421 }
2422
2423 // This notify_all() will ensure that a thread that called
2424 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2425 // and it's waiting for a full GC to finish will be woken up. It is
2426 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2427 FullGCCount_lock->notify_all();
2428 }
2429
2430 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2431 _concurrent_cycle_started = true;
2432 _gc_timer_cm->register_gc_start(start_time);
2433
2434 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2435 trace_heap_before_gc(_gc_tracer_cm);
2436 }
2437
2438 void G1CollectedHeap::register_concurrent_cycle_end() {
2439 if (_concurrent_cycle_started) {
2440 if (_cm->has_aborted()) {
2441 _gc_tracer_cm->report_concurrent_mode_failure();
2442 }
2443
2444 _gc_timer_cm->register_gc_end();
2445 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2446
2447 _concurrent_cycle_started = false;
2448 }
2449 }
2450
2451 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2452 if (_concurrent_cycle_started) {
2453 trace_heap_after_gc(_gc_tracer_cm);
2454 }
2455 }
2456
2457 G1YCType G1CollectedHeap::yc_type() {
2458 bool is_young = g1_policy()->gcs_are_young();
2459 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2460 bool is_during_mark = mark_in_progress();
2461
2462 if (is_initial_mark) {
2463 return InitialMark;
2464 } else if (is_during_mark) {
2465 return DuringMark;
2466 } else if (is_young) {
2467 return Normal;
2468 } else {
2469 return Mixed;
2470 }
2471 }
2472
2473 void G1CollectedHeap::collect(GCCause::Cause cause) {
2474 assert_heap_not_locked();
2475
2476 unsigned int gc_count_before;
2477 unsigned int old_marking_count_before;
2478 bool retry_gc;
2479
2480 do {
2481 retry_gc = false;
2482
2483 {
2484 MutexLocker ml(Heap_lock);
2485
2486 // Read the GC count while holding the Heap_lock
2487 gc_count_before = total_collections();
2488 old_marking_count_before = _old_marking_cycles_started;
2489 }
2490
2491 if (should_do_concurrent_full_gc(cause)) {
2492 // Schedule an initial-mark evacuation pause that will start a
2493 // concurrent cycle. We're setting word_size to 0 which means that
2494 // we are not requesting a post-GC allocation.
2495 VM_G1IncCollectionPause op(gc_count_before,
2496 0, /* word_size */
2497 true, /* should_initiate_conc_mark */
2498 g1_policy()->max_pause_time_ms(),
2499 cause);
2500 op.set_allocation_context(AllocationContext::current());
2501
2502 VMThread::execute(&op);
2503 if (!op.pause_succeeded()) {
2504 if (old_marking_count_before == _old_marking_cycles_started) {
2505 retry_gc = op.should_retry_gc();
2506 } else {
2507 // A Full GC happened while we were trying to schedule the
2508 // initial-mark GC. No point in starting a new cycle given
2509 // that the whole heap was collected anyway.
2510 }
2511
2512 if (retry_gc) {
2513 if (GC_locker::is_active_and_needs_gc()) {
2514 GC_locker::stall_until_clear();
2515 }
2516 }
2517 }
2518 } else {
2519 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2520 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2521
2522 // Schedule a standard evacuation pause. We're setting word_size
2523 // to 0 which means that we are not requesting a post-GC allocation.
2524 VM_G1IncCollectionPause op(gc_count_before,
2525 0, /* word_size */
2526 false, /* should_initiate_conc_mark */
2527 g1_policy()->max_pause_time_ms(),
2528 cause);
2529 VMThread::execute(&op);
2530 } else {
2531 // Schedule a Full GC.
2532 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2533 VMThread::execute(&op);
2534 }
2535 }
2536 } while (retry_gc);
2537 }
2538
2539 bool G1CollectedHeap::is_in(const void* p) const {
2540 if (_hrm.reserved().contains(p)) {
2541 // Given that we know that p is in the reserved space,
2542 // heap_region_containing_raw() should successfully
2543 // return the containing region.
2544 HeapRegion* hr = heap_region_containing_raw(p);
2545 return hr->is_in(p);
2546 } else {
2547 return false;
2548 }
2549 }
2550
2551 #ifdef ASSERT
2552 bool G1CollectedHeap::is_in_exact(const void* p) const {
2553 bool contains = reserved_region().contains(p);
2554 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2555 if (contains && available) {
2556 return true;
2557 } else {
2558 return false;
2559 }
2560 }
2561 #endif
2562
2563 // Iteration functions.
2564
2565 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2566
2567 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2568 ExtendedOopClosure* _cl;
2569 public:
2570 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2571 bool doHeapRegion(HeapRegion* r) {
2572 if (!r->continuesHumongous()) {
2573 r->oop_iterate(_cl);
2574 }
2575 return false;
2576 }
2577 };
2578
2579 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2580 IterateOopClosureRegionClosure blk(cl);
2581 heap_region_iterate(&blk);
2582 }
2583
2584 // Iterates an ObjectClosure over all objects within a HeapRegion.
2585
2586 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2587 ObjectClosure* _cl;
2588 public:
2589 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2590 bool doHeapRegion(HeapRegion* r) {
2591 if (! r->continuesHumongous()) {
2592 r->object_iterate(_cl);
2593 }
2594 return false;
2595 }
2596 };
2597
2598 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2599 IterateObjectClosureRegionClosure blk(cl);
2600 heap_region_iterate(&blk);
2601 }
2602
2603 // Calls a SpaceClosure on a HeapRegion.
2604
2605 class SpaceClosureRegionClosure: public HeapRegionClosure {
2606 SpaceClosure* _cl;
2607 public:
2608 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2609 bool doHeapRegion(HeapRegion* r) {
2610 _cl->do_space(r);
2611 return false;
2612 }
2613 };
2614
2615 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2616 SpaceClosureRegionClosure blk(cl);
2617 heap_region_iterate(&blk);
2618 }
2619
2620 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2621 _hrm.iterate(cl);
2622 }
2623
2624 void
2625 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2626 uint worker_id,
2627 uint num_workers,
2628 jint claim_value) const {
2629 _hrm.par_iterate(cl, worker_id, num_workers, claim_value);
2630 }
2631
2632 class ResetClaimValuesClosure: public HeapRegionClosure {
2633 public:
2634 bool doHeapRegion(HeapRegion* r) {
2635 r->set_claim_value(HeapRegion::InitialClaimValue);
2636 return false;
2637 }
2638 };
2639
2640 void G1CollectedHeap::reset_heap_region_claim_values() {
2641 ResetClaimValuesClosure blk;
2642 heap_region_iterate(&blk);
2643 }
2644
2645 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2646 ResetClaimValuesClosure blk;
2647 collection_set_iterate(&blk);
2648 }
2649
2650 #ifdef ASSERT
2651 // This checks whether all regions in the heap have the correct claim
2652 // value. I also piggy-backed on this a check to ensure that the
2653 // humongous_start_region() information on "continues humongous"
2654 // regions is correct.
2655
2656 class CheckClaimValuesClosure : public HeapRegionClosure {
2657 private:
2658 jint _claim_value;
2659 uint _failures;
2660 HeapRegion* _sh_region;
2661
2662 public:
2663 CheckClaimValuesClosure(jint claim_value) :
2664 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2665 bool doHeapRegion(HeapRegion* r) {
2666 if (r->claim_value() != _claim_value) {
2667 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2668 "claim value = %d, should be %d",
2669 HR_FORMAT_PARAMS(r),
2670 r->claim_value(), _claim_value);
2671 ++_failures;
2672 }
2673 if (!r->isHumongous()) {
2674 _sh_region = NULL;
2675 } else if (r->startsHumongous()) {
2676 _sh_region = r;
2677 } else if (r->continuesHumongous()) {
2678 if (r->humongous_start_region() != _sh_region) {
2679 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2680 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2681 HR_FORMAT_PARAMS(r),
2682 r->humongous_start_region(),
2683 _sh_region);
2684 ++_failures;
2685 }
2686 }
2687 return false;
2688 }
2689 uint failures() { return _failures; }
2690 };
2691
2692 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2693 CheckClaimValuesClosure cl(claim_value);
2694 heap_region_iterate(&cl);
2695 return cl.failures() == 0;
2696 }
2697
2698 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2699 private:
2700 jint _claim_value;
2701 uint _failures;
2702
2703 public:
2704 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2705 _claim_value(claim_value), _failures(0) { }
2706
2707 uint failures() { return _failures; }
2708
2709 bool doHeapRegion(HeapRegion* hr) {
2710 assert(hr->in_collection_set(), "how?");
2711 assert(!hr->isHumongous(), "H-region in CSet");
2712 if (hr->claim_value() != _claim_value) {
2713 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2714 "claim value = %d, should be %d",
2715 HR_FORMAT_PARAMS(hr),
2716 hr->claim_value(), _claim_value);
2717 _failures += 1;
2718 }
2719 return false;
2720 }
2721 };
2722
2723 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2724 CheckClaimValuesInCSetHRClosure cl(claim_value);
2725 collection_set_iterate(&cl);
2726 return cl.failures() == 0;
2727 }
2728 #endif // ASSERT
2729
2730 // Clear the cached CSet starting regions and (more importantly)
2731 // the time stamps. Called when we reset the GC time stamp.
2732 void G1CollectedHeap::clear_cset_start_regions() {
2733 assert(_worker_cset_start_region != NULL, "sanity");
2734 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2735
2736 int n_queues = MAX2((int)ParallelGCThreads, 1);
2737 for (int i = 0; i < n_queues; i++) {
2738 _worker_cset_start_region[i] = NULL;
2739 _worker_cset_start_region_time_stamp[i] = 0;
2740 }
2741 }
2742
2743 // Given the id of a worker, obtain or calculate a suitable
2744 // starting region for iterating over the current collection set.
2745 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2746 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2747
2748 HeapRegion* result = NULL;
2749 unsigned gc_time_stamp = get_gc_time_stamp();
2750
2751 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2752 // Cached starting region for current worker was set
2753 // during the current pause - so it's valid.
2754 // Note: the cached starting heap region may be NULL
2755 // (when the collection set is empty).
2756 result = _worker_cset_start_region[worker_i];
2757 assert(result == NULL || result->in_collection_set(), "sanity");
2758 return result;
2759 }
2760
2761 // The cached entry was not valid so let's calculate
2762 // a suitable starting heap region for this worker.
2763
2764 // We want the parallel threads to start their collection
2765 // set iteration at different collection set regions to
2766 // avoid contention.
2767 // If we have:
2768 // n collection set regions
2769 // p threads
2770 // Then thread t will start at region floor ((t * n) / p)
2771
2772 result = g1_policy()->collection_set();
2773 if (G1CollectedHeap::use_parallel_gc_threads()) {
2774 uint cs_size = g1_policy()->cset_region_length();
2775 uint active_workers = workers()->active_workers();
2776 assert(UseDynamicNumberOfGCThreads ||
2777 active_workers == workers()->total_workers(),
2778 "Unless dynamic should use total workers");
2779
2780 uint end_ind = (cs_size * worker_i) / active_workers;
2781 uint start_ind = 0;
2782
2783 if (worker_i > 0 &&
2784 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2785 // Previous workers starting region is valid
2786 // so let's iterate from there
2787 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2788 result = _worker_cset_start_region[worker_i - 1];
2789 }
2790
2791 for (uint i = start_ind; i < end_ind; i++) {
2792 result = result->next_in_collection_set();
2793 }
2794 }
2795
2796 // Note: the calculated starting heap region may be NULL
2797 // (when the collection set is empty).
2798 assert(result == NULL || result->in_collection_set(), "sanity");
2799 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2800 "should be updated only once per pause");
2801 _worker_cset_start_region[worker_i] = result;
2802 OrderAccess::storestore();
2803 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2804 return result;
2805 }
2806
2807 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2808 HeapRegion* r = g1_policy()->collection_set();
2809 while (r != NULL) {
2810 HeapRegion* next = r->next_in_collection_set();
2811 if (cl->doHeapRegion(r)) {
2812 cl->incomplete();
2813 return;
2814 }
2815 r = next;
2816 }
2817 }
2818
2819 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2820 HeapRegionClosure *cl) {
2821 if (r == NULL) {
2822 // The CSet is empty so there's nothing to do.
2823 return;
2824 }
2825
2826 assert(r->in_collection_set(),
2827 "Start region must be a member of the collection set.");
2828 HeapRegion* cur = r;
2829 while (cur != NULL) {
2830 HeapRegion* next = cur->next_in_collection_set();
2831 if (cl->doHeapRegion(cur) && false) {
2832 cl->incomplete();
2833 return;
2834 }
2835 cur = next;
2836 }
2837 cur = g1_policy()->collection_set();
2838 while (cur != r) {
2839 HeapRegion* next = cur->next_in_collection_set();
2840 if (cl->doHeapRegion(cur) && false) {
2841 cl->incomplete();
2842 return;
2843 }
2844 cur = next;
2845 }
2846 }
2847
2848 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2849 HeapRegion* result = _hrm.next_region_in_heap(from);
2850 while (result != NULL && result->isHumongous()) {
2851 result = _hrm.next_region_in_heap(result);
2852 }
2853 return result;
2854 }
2855
2856 Space* G1CollectedHeap::space_containing(const void* addr) const {
2857 return heap_region_containing(addr);
2858 }
2859
2860 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2861 Space* sp = space_containing(addr);
2862 return sp->block_start(addr);
2863 }
2864
2865 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2866 Space* sp = space_containing(addr);
2867 return sp->block_size(addr);
2868 }
2869
2870 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2871 Space* sp = space_containing(addr);
2872 return sp->block_is_obj(addr);
2873 }
2874
2875 bool G1CollectedHeap::supports_tlab_allocation() const {
2876 return true;
2877 }
2878
2879 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2880 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2881 }
2882
2883 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2884 return young_list()->eden_used_bytes();
2885 }
2886
2887 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2888 // must be smaller than the humongous object limit.
2889 size_t G1CollectedHeap::max_tlab_size() const {
2890 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2891 }
2892
2893 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2894 // Return the remaining space in the cur alloc region, but not less than
2895 // the min TLAB size.
2896
2897 // Also, this value can be at most the humongous object threshold,
2898 // since we can't allow tlabs to grow big enough to accommodate
2899 // humongous objects.
2900
2901 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2902 size_t max_tlab = max_tlab_size() * wordSize;
2903 if (hr == NULL) {
2904 return max_tlab;
2905 } else {
2906 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2907 }
2908 }
2909
2910 size_t G1CollectedHeap::max_capacity() const {
2911 return _hrm.reserved().byte_size();
2912 }
2913
2914 jlong G1CollectedHeap::millis_since_last_gc() {
2915 // assert(false, "NYI");
2916 return 0;
2917 }
2918
2919 void G1CollectedHeap::prepare_for_verify() {
2920 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2921 ensure_parsability(false);
2922 }
2923 g1_rem_set()->prepare_for_verify();
2924 }
2925
2926 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2927 VerifyOption vo) {
2928 switch (vo) {
2929 case VerifyOption_G1UsePrevMarking:
2930 return hr->obj_allocated_since_prev_marking(obj);
2931 case VerifyOption_G1UseNextMarking:
2932 return hr->obj_allocated_since_next_marking(obj);
2933 case VerifyOption_G1UseMarkWord:
2934 return false;
2935 default:
2936 ShouldNotReachHere();
2937 }
2938 return false; // keep some compilers happy
2939 }
2940
2941 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2942 switch (vo) {
2943 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2944 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2945 case VerifyOption_G1UseMarkWord: return NULL;
2946 default: ShouldNotReachHere();
2947 }
2948 return NULL; // keep some compilers happy
2949 }
2950
2951 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2952 switch (vo) {
2953 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2954 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2955 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2956 default: ShouldNotReachHere();
2957 }
2958 return false; // keep some compilers happy
2959 }
2960
2961 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2962 switch (vo) {
2963 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2964 case VerifyOption_G1UseNextMarking: return "NTAMS";
2965 case VerifyOption_G1UseMarkWord: return "NONE";
2966 default: ShouldNotReachHere();
2967 }
2968 return NULL; // keep some compilers happy
2969 }
2970
2971 class VerifyRootsClosure: public OopClosure {
2972 private:
2973 G1CollectedHeap* _g1h;
2974 VerifyOption _vo;
2975 bool _failures;
2976 public:
2977 // _vo == UsePrevMarking -> use "prev" marking information,
2978 // _vo == UseNextMarking -> use "next" marking information,
2979 // _vo == UseMarkWord -> use mark word from object header.
2980 VerifyRootsClosure(VerifyOption vo) :
2981 _g1h(G1CollectedHeap::heap()),
2982 _vo(vo),
2983 _failures(false) { }
2984
2985 bool failures() { return _failures; }
2986
2987 template <class T> void do_oop_nv(T* p) {
2988 T heap_oop = oopDesc::load_heap_oop(p);
2989 if (!oopDesc::is_null(heap_oop)) {
2990 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2991 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2992 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2993 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2994 if (_vo == VerifyOption_G1UseMarkWord) {
2995 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2996 }
2997 obj->print_on(gclog_or_tty);
2998 _failures = true;
2999 }
3000 }
3001 }
3002
3003 void do_oop(oop* p) { do_oop_nv(p); }
3004 void do_oop(narrowOop* p) { do_oop_nv(p); }
3005 };
3006
3007 class G1VerifyCodeRootOopClosure: public OopClosure {
3008 G1CollectedHeap* _g1h;
3009 OopClosure* _root_cl;
3010 nmethod* _nm;
3011 VerifyOption _vo;
3012 bool _failures;
3013
3014 template <class T> void do_oop_work(T* p) {
3015 // First verify that this root is live
3016 _root_cl->do_oop(p);
3017
3018 if (!G1VerifyHeapRegionCodeRoots) {
3019 // We're not verifying the code roots attached to heap region.
3020 return;
3021 }
3022
3023 // Don't check the code roots during marking verification in a full GC
3024 if (_vo == VerifyOption_G1UseMarkWord) {
3025 return;
3026 }
3027
3028 // Now verify that the current nmethod (which contains p) is
3029 // in the code root list of the heap region containing the
3030 // object referenced by p.
3031
3032 T heap_oop = oopDesc::load_heap_oop(p);
3033 if (!oopDesc::is_null(heap_oop)) {
3034 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3035
3036 // Now fetch the region containing the object
3037 HeapRegion* hr = _g1h->heap_region_containing(obj);
3038 HeapRegionRemSet* hrrs = hr->rem_set();
3039 // Verify that the strong code root list for this region
3040 // contains the nmethod
3041 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3042 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3043 "from nmethod "PTR_FORMAT" not in strong "
3044 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3045 p, _nm, hr->bottom(), hr->end());
3046 _failures = true;
3047 }
3048 }
3049 }
3050
3051 public:
3052 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3053 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3054
3055 void do_oop(oop* p) { do_oop_work(p); }
3056 void do_oop(narrowOop* p) { do_oop_work(p); }
3057
3058 void set_nmethod(nmethod* nm) { _nm = nm; }
3059 bool failures() { return _failures; }
3060 };
3061
3062 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3063 G1VerifyCodeRootOopClosure* _oop_cl;
3064
3065 public:
3066 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3067 _oop_cl(oop_cl) {}
3068
3069 void do_code_blob(CodeBlob* cb) {
3070 nmethod* nm = cb->as_nmethod_or_null();
3071 if (nm != NULL) {
3072 _oop_cl->set_nmethod(nm);
3073 nm->oops_do(_oop_cl);
3074 }
3075 }
3076 };
3077
3078 class YoungRefCounterClosure : public OopClosure {
3079 G1CollectedHeap* _g1h;
3080 int _count;
3081 public:
3082 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3083 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3084 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3085
3086 int count() { return _count; }
3087 void reset_count() { _count = 0; };
3088 };
3089
3090 class VerifyKlassClosure: public KlassClosure {
3091 YoungRefCounterClosure _young_ref_counter_closure;
3092 OopClosure *_oop_closure;
3093 public:
3094 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3095 void do_klass(Klass* k) {
3096 k->oops_do(_oop_closure);
3097
3098 _young_ref_counter_closure.reset_count();
3099 k->oops_do(&_young_ref_counter_closure);
3100 if (_young_ref_counter_closure.count() > 0) {
3101 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3102 }
3103 }
3104 };
3105
3106 class VerifyLivenessOopClosure: public OopClosure {
3107 G1CollectedHeap* _g1h;
3108 VerifyOption _vo;
3109 public:
3110 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3111 _g1h(g1h), _vo(vo)
3112 { }
3113 void do_oop(narrowOop *p) { do_oop_work(p); }
3114 void do_oop( oop *p) { do_oop_work(p); }
3115
3116 template <class T> void do_oop_work(T *p) {
3117 oop obj = oopDesc::load_decode_heap_oop(p);
3118 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3119 "Dead object referenced by a not dead object");
3120 }
3121 };
3122
3123 class VerifyObjsInRegionClosure: public ObjectClosure {
3124 private:
3125 G1CollectedHeap* _g1h;
3126 size_t _live_bytes;
3127 HeapRegion *_hr;
3128 VerifyOption _vo;
3129 public:
3130 // _vo == UsePrevMarking -> use "prev" marking information,
3131 // _vo == UseNextMarking -> use "next" marking information,
3132 // _vo == UseMarkWord -> use mark word from object header.
3133 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3134 : _live_bytes(0), _hr(hr), _vo(vo) {
3135 _g1h = G1CollectedHeap::heap();
3136 }
3137 void do_object(oop o) {
3138 VerifyLivenessOopClosure isLive(_g1h, _vo);
3139 assert(o != NULL, "Huh?");
3140 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3141 // If the object is alive according to the mark word,
3142 // then verify that the marking information agrees.
3143 // Note we can't verify the contra-positive of the
3144 // above: if the object is dead (according to the mark
3145 // word), it may not be marked, or may have been marked
3146 // but has since became dead, or may have been allocated
3147 // since the last marking.
3148 if (_vo == VerifyOption_G1UseMarkWord) {
3149 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3150 }
3151
3152 o->oop_iterate_no_header(&isLive);
3153 if (!_hr->obj_allocated_since_prev_marking(o)) {
3154 size_t obj_size = o->size(); // Make sure we don't overflow
3155 _live_bytes += (obj_size * HeapWordSize);
3156 }
3157 }
3158 }
3159 size_t live_bytes() { return _live_bytes; }
3160 };
3161
3162 class PrintObjsInRegionClosure : public ObjectClosure {
3163 HeapRegion *_hr;
3164 G1CollectedHeap *_g1;
3165 public:
3166 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3167 _g1 = G1CollectedHeap::heap();
3168 };
3169
3170 void do_object(oop o) {
3171 if (o != NULL) {
3172 HeapWord *start = (HeapWord *) o;
3173 size_t word_sz = o->size();
3174 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3175 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3176 (void*) o, word_sz,
3177 _g1->isMarkedPrev(o),
3178 _g1->isMarkedNext(o),
3179 _hr->obj_allocated_since_prev_marking(o));
3180 HeapWord *end = start + word_sz;
3181 HeapWord *cur;
3182 int *val;
3183 for (cur = start; cur < end; cur++) {
3184 val = (int *) cur;
3185 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3186 }
3187 }
3188 }
3189 };
3190
3191 class VerifyRegionClosure: public HeapRegionClosure {
3192 private:
3193 bool _par;
3194 VerifyOption _vo;
3195 bool _failures;
3196 public:
3197 // _vo == UsePrevMarking -> use "prev" marking information,
3198 // _vo == UseNextMarking -> use "next" marking information,
3199 // _vo == UseMarkWord -> use mark word from object header.
3200 VerifyRegionClosure(bool par, VerifyOption vo)
3201 : _par(par),
3202 _vo(vo),
3203 _failures(false) {}
3204
3205 bool failures() {
3206 return _failures;
3207 }
3208
3209 bool doHeapRegion(HeapRegion* r) {
3210 if (!r->continuesHumongous()) {
3211 bool failures = false;
3212 r->verify(_vo, &failures);
3213 if (failures) {
3214 _failures = true;
3215 } else {
3216 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3217 r->object_iterate(¬_dead_yet_cl);
3218 if (_vo != VerifyOption_G1UseNextMarking) {
3219 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3220 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3221 "max_live_bytes "SIZE_FORMAT" "
3222 "< calculated "SIZE_FORMAT,
3223 r->bottom(), r->end(),
3224 r->max_live_bytes(),
3225 not_dead_yet_cl.live_bytes());
3226 _failures = true;
3227 }
3228 } else {
3229 // When vo == UseNextMarking we cannot currently do a sanity
3230 // check on the live bytes as the calculation has not been
3231 // finalized yet.
3232 }
3233 }
3234 }
3235 return false; // stop the region iteration if we hit a failure
3236 }
3237 };
3238
3239 // This is the task used for parallel verification of the heap regions
3240
3241 class G1ParVerifyTask: public AbstractGangTask {
3242 private:
3243 G1CollectedHeap* _g1h;
3244 VerifyOption _vo;
3245 bool _failures;
3246
3247 public:
3248 // _vo == UsePrevMarking -> use "prev" marking information,
3249 // _vo == UseNextMarking -> use "next" marking information,
3250 // _vo == UseMarkWord -> use mark word from object header.
3251 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3252 AbstractGangTask("Parallel verify task"),
3253 _g1h(g1h),
3254 _vo(vo),
3255 _failures(false) { }
3256
3257 bool failures() {
3258 return _failures;
3259 }
3260
3261 void work(uint worker_id) {
3262 HandleMark hm;
3263 VerifyRegionClosure blk(true, _vo);
3264 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3265 _g1h->workers()->active_workers(),
3266 HeapRegion::ParVerifyClaimValue);
3267 if (blk.failures()) {
3268 _failures = true;
3269 }
3270 }
3271 };
3272
3273 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3274 if (SafepointSynchronize::is_at_safepoint()) {
3275 assert(Thread::current()->is_VM_thread(),
3276 "Expected to be executed serially by the VM thread at this point");
3277
3278 if (!silent) { gclog_or_tty->print("Roots "); }
3279 VerifyRootsClosure rootsCl(vo);
3280 VerifyKlassClosure klassCl(this, &rootsCl);
3281 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3282
3283 // We apply the relevant closures to all the oops in the
3284 // system dictionary, class loader data graph, the string table
3285 // and the nmethods in the code cache.
3286 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3287 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3288
3289 process_all_roots(true, // activate StrongRootsScope
3290 SO_AllCodeCache, // roots scanning options
3291 &rootsCl,
3292 &cldCl,
3293 &blobsCl);
3294
3295 bool failures = rootsCl.failures() || codeRootsCl.failures();
3296
3297 if (vo != VerifyOption_G1UseMarkWord) {
3298 // If we're verifying during a full GC then the region sets
3299 // will have been torn down at the start of the GC. Therefore
3300 // verifying the region sets will fail. So we only verify
3301 // the region sets when not in a full GC.
3302 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3303 verify_region_sets();
3304 }
3305
3306 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3307 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3308 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3309 "sanity check");
3310
3311 G1ParVerifyTask task(this, vo);
3312 assert(UseDynamicNumberOfGCThreads ||
3313 workers()->active_workers() == workers()->total_workers(),
3314 "If not dynamic should be using all the workers");
3315 int n_workers = workers()->active_workers();
3316 set_par_threads(n_workers);
3317 workers()->run_task(&task);
3318 set_par_threads(0);
3319 if (task.failures()) {
3320 failures = true;
3321 }
3322
3323 // Checks that the expected amount of parallel work was done.
3324 // The implication is that n_workers is > 0.
3325 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3326 "sanity check");
3327
3328 reset_heap_region_claim_values();
3329
3330 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3331 "sanity check");
3332 } else {
3333 VerifyRegionClosure blk(false, vo);
3334 heap_region_iterate(&blk);
3335 if (blk.failures()) {
3336 failures = true;
3337 }
3338 }
3339 if (!silent) gclog_or_tty->print("RemSet ");
3340 rem_set()->verify();
3341
3342 if (G1StringDedup::is_enabled()) {
3343 if (!silent) gclog_or_tty->print("StrDedup ");
3344 G1StringDedup::verify();
3345 }
3346
3347 if (failures) {
3348 gclog_or_tty->print_cr("Heap:");
3349 // It helps to have the per-region information in the output to
3350 // help us track down what went wrong. This is why we call
3351 // print_extended_on() instead of print_on().
3352 print_extended_on(gclog_or_tty);
3353 gclog_or_tty->cr();
3354 #ifndef PRODUCT
3355 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3356 concurrent_mark()->print_reachable("at-verification-failure",
3357 vo, false /* all */);
3358 }
3359 #endif
3360 gclog_or_tty->flush();
3361 }
3362 guarantee(!failures, "there should not have been any failures");
3363 } else {
3364 if (!silent) {
3365 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3366 if (G1StringDedup::is_enabled()) {
3367 gclog_or_tty->print(", StrDedup");
3368 }
3369 gclog_or_tty->print(") ");
3370 }
3371 }
3372 }
3373
3374 void G1CollectedHeap::verify(bool silent) {
3375 verify(silent, VerifyOption_G1UsePrevMarking);
3376 }
3377
3378 double G1CollectedHeap::verify(bool guard, const char* msg) {
3379 double verify_time_ms = 0.0;
3380
3381 if (guard && total_collections() >= VerifyGCStartAt) {
3382 double verify_start = os::elapsedTime();
3383 HandleMark hm; // Discard invalid handles created during verification
3384 prepare_for_verify();
3385 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3386 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3387 }
3388
3389 return verify_time_ms;
3390 }
3391
3392 void G1CollectedHeap::verify_before_gc() {
3393 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3394 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3395 }
3396
3397 void G1CollectedHeap::verify_after_gc() {
3398 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3399 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3400 }
3401
3402 class PrintRegionClosure: public HeapRegionClosure {
3403 outputStream* _st;
3404 public:
3405 PrintRegionClosure(outputStream* st) : _st(st) {}
3406 bool doHeapRegion(HeapRegion* r) {
3407 r->print_on(_st);
3408 return false;
3409 }
3410 };
3411
3412 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3413 const HeapRegion* hr,
3414 const VerifyOption vo) const {
3415 switch (vo) {
3416 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3417 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3418 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3419 default: ShouldNotReachHere();
3420 }
3421 return false; // keep some compilers happy
3422 }
3423
3424 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3425 const VerifyOption vo) const {
3426 switch (vo) {
3427 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3428 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3429 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3430 default: ShouldNotReachHere();
3431 }
3432 return false; // keep some compilers happy
3433 }
3434
3435 void G1CollectedHeap::print_on(outputStream* st) const {
3436 st->print(" %-20s", "garbage-first heap");
3437 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3438 capacity()/K, used_unlocked()/K);
3439 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3440 _hrm.reserved().start(),
3441 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3442 _hrm.reserved().end());
3443 st->cr();
3444 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3445 uint young_regions = _young_list->length();
3446 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3447 (size_t) young_regions * HeapRegion::GrainBytes / K);
3448 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3449 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3450 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3451 st->cr();
3452 MetaspaceAux::print_on(st);
3453 }
3454
3455 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3456 print_on(st);
3457
3458 // Print the per-region information.
3459 st->cr();
3460 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3461 "HS=humongous(starts), HC=humongous(continues), "
3462 "CS=collection set, F=free, TS=gc time stamp, "
3463 "PTAMS=previous top-at-mark-start, "
3464 "NTAMS=next top-at-mark-start)");
3465 PrintRegionClosure blk(st);
3466 heap_region_iterate(&blk);
3467 }
3468
3469 void G1CollectedHeap::print_on_error(outputStream* st) const {
3470 this->CollectedHeap::print_on_error(st);
3471
3472 if (_cm != NULL) {
3473 st->cr();
3474 _cm->print_on_error(st);
3475 }
3476 }
3477
3478 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3479 if (G1CollectedHeap::use_parallel_gc_threads()) {
3480 workers()->print_worker_threads_on(st);
3481 }
3482 _cmThread->print_on(st);
3483 st->cr();
3484 _cm->print_worker_threads_on(st);
3485 _cg1r->print_worker_threads_on(st);
3486 if (G1StringDedup::is_enabled()) {
3487 G1StringDedup::print_worker_threads_on(st);
3488 }
3489 }
3490
3491 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3492 if (G1CollectedHeap::use_parallel_gc_threads()) {
3493 workers()->threads_do(tc);
3494 }
3495 tc->do_thread(_cmThread);
3496 _cg1r->threads_do(tc);
3497 if (G1StringDedup::is_enabled()) {
3498 G1StringDedup::threads_do(tc);
3499 }
3500 }
3501
3502 void G1CollectedHeap::print_tracing_info() const {
3503 // We'll overload this to mean "trace GC pause statistics."
3504 if (TraceGen0Time || TraceGen1Time) {
3505 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3506 // to that.
3507 g1_policy()->print_tracing_info();
3508 }
3509 if (G1SummarizeRSetStats) {
3510 g1_rem_set()->print_summary_info();
3511 }
3512 if (G1SummarizeConcMark) {
3513 concurrent_mark()->print_summary_info();
3514 }
3515 g1_policy()->print_yg_surv_rate_info();
3516 SpecializationStats::print();
3517 }
3518
3519 #ifndef PRODUCT
3520 // Helpful for debugging RSet issues.
3521
3522 class PrintRSetsClosure : public HeapRegionClosure {
3523 private:
3524 const char* _msg;
3525 size_t _occupied_sum;
3526
3527 public:
3528 bool doHeapRegion(HeapRegion* r) {
3529 HeapRegionRemSet* hrrs = r->rem_set();
3530 size_t occupied = hrrs->occupied();
3531 _occupied_sum += occupied;
3532
3533 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3534 HR_FORMAT_PARAMS(r));
3535 if (occupied == 0) {
3536 gclog_or_tty->print_cr(" RSet is empty");
3537 } else {
3538 hrrs->print();
3539 }
3540 gclog_or_tty->print_cr("----------");
3541 return false;
3542 }
3543
3544 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3545 gclog_or_tty->cr();
3546 gclog_or_tty->print_cr("========================================");
3547 gclog_or_tty->print_cr("%s", msg);
3548 gclog_or_tty->cr();
3549 }
3550
3551 ~PrintRSetsClosure() {
3552 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3553 gclog_or_tty->print_cr("========================================");
3554 gclog_or_tty->cr();
3555 }
3556 };
3557
3558 void G1CollectedHeap::print_cset_rsets() {
3559 PrintRSetsClosure cl("Printing CSet RSets");
3560 collection_set_iterate(&cl);
3561 }
3562
3563 void G1CollectedHeap::print_all_rsets() {
3564 PrintRSetsClosure cl("Printing All RSets");;
3565 heap_region_iterate(&cl);
3566 }
3567 #endif // PRODUCT
3568
3569 G1CollectedHeap* G1CollectedHeap::heap() {
3570 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3571 "not a garbage-first heap");
3572 return _g1h;
3573 }
3574
3575 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3576 // always_do_update_barrier = false;
3577 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3578 // Fill TLAB's and such
3579 accumulate_statistics_all_tlabs();
3580 ensure_parsability(true);
3581
3582 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3583 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3584 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3585 }
3586 }
3587
3588 void G1CollectedHeap::gc_epilogue(bool full) {
3589
3590 if (G1SummarizeRSetStats &&
3591 (G1SummarizeRSetStatsPeriod > 0) &&
3592 // we are at the end of the GC. Total collections has already been increased.
3593 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3594 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3595 }
3596
3597 // FIXME: what is this about?
3598 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3599 // is set.
3600 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3601 "derived pointer present"));
3602 // always_do_update_barrier = true;
3603
3604 resize_all_tlabs();
3605 allocation_context_stats().update(full);
3606
3607 // We have just completed a GC. Update the soft reference
3608 // policy with the new heap occupancy
3609 Universe::update_heap_info_at_gc();
3610 }
3611
3612 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3613 unsigned int gc_count_before,
3614 bool* succeeded,
3615 GCCause::Cause gc_cause) {
3616 assert_heap_not_locked_and_not_at_safepoint();
3617 g1_policy()->record_stop_world_start();
3618 VM_G1IncCollectionPause op(gc_count_before,
3619 word_size,
3620 false, /* should_initiate_conc_mark */
3621 g1_policy()->max_pause_time_ms(),
3622 gc_cause);
3623
3624 op.set_allocation_context(AllocationContext::current());
3625 VMThread::execute(&op);
3626
3627 HeapWord* result = op.result();
3628 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3629 assert(result == NULL || ret_succeeded,
3630 "the result should be NULL if the VM did not succeed");
3631 *succeeded = ret_succeeded;
3632
3633 assert_heap_not_locked();
3634 return result;
3635 }
3636
3637 void
3638 G1CollectedHeap::doConcurrentMark() {
3639 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3640 if (!_cmThread->in_progress()) {
3641 _cmThread->set_started();
3642 CGC_lock->notify();
3643 }
3644 }
3645
3646 size_t G1CollectedHeap::pending_card_num() {
3647 size_t extra_cards = 0;
3648 JavaThread *curr = Threads::first();
3649 while (curr != NULL) {
3650 DirtyCardQueue& dcq = curr->dirty_card_queue();
3651 extra_cards += dcq.size();
3652 curr = curr->next();
3653 }
3654 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3655 size_t buffer_size = dcqs.buffer_size();
3656 size_t buffer_num = dcqs.completed_buffers_num();
3657
3658 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3659 // in bytes - not the number of 'entries'. We need to convert
3660 // into a number of cards.
3661 return (buffer_size * buffer_num + extra_cards) / oopSize;
3662 }
3663
3664 size_t G1CollectedHeap::cards_scanned() {
3665 return g1_rem_set()->cardsScanned();
3666 }
3667
3668 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3669 HeapRegion* region = region_at(index);
3670 assert(region->startsHumongous(), "Must start a humongous object");
3671 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3672 }
3673
3674 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3675 private:
3676 size_t _total_humongous;
3677 size_t _candidate_humongous;
3678 public:
3679 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3680 }
3681
3682 virtual bool doHeapRegion(HeapRegion* r) {
3683 if (!r->startsHumongous()) {
3684 return false;
3685 }
3686 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3687
3688 uint region_idx = r->hrm_index();
3689 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3690 // Is_candidate already filters out humongous regions with some remembered set.
3691 // This will not lead to humongous object that we mistakenly keep alive because
3692 // during young collection the remembered sets will only be added to.
3693 if (is_candidate) {
3694 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3695 _candidate_humongous++;
3696 }
3697 _total_humongous++;
3698
3699 return false;
3700 }
3701
3702 size_t total_humongous() const { return _total_humongous; }
3703 size_t candidate_humongous() const { return _candidate_humongous; }
3704 };
3705
3706 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3707 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3708 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3709 return;
3710 }
3711
3712 RegisterHumongousWithInCSetFastTestClosure cl;
3713 heap_region_iterate(&cl);
3714 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3715 cl.candidate_humongous());
3716 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3717
3718 if (_has_humongous_reclaim_candidates) {
3719 clear_humongous_is_live_table();
3720 }
3721 }
3722
3723 void
3724 G1CollectedHeap::setup_surviving_young_words() {
3725 assert(_surviving_young_words == NULL, "pre-condition");
3726 uint array_length = g1_policy()->young_cset_region_length();
3727 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3728 if (_surviving_young_words == NULL) {
3729 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3730 "Not enough space for young surv words summary.");
3731 }
3732 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3733 #ifdef ASSERT
3734 for (uint i = 0; i < array_length; ++i) {
3735 assert( _surviving_young_words[i] == 0, "memset above" );
3736 }
3737 #endif // !ASSERT
3738 }
3739
3740 void
3741 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3742 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3743 uint array_length = g1_policy()->young_cset_region_length();
3744 for (uint i = 0; i < array_length; ++i) {
3745 _surviving_young_words[i] += surv_young_words[i];
3746 }
3747 }
3748
3749 void
3750 G1CollectedHeap::cleanup_surviving_young_words() {
3751 guarantee( _surviving_young_words != NULL, "pre-condition" );
3752 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3753 _surviving_young_words = NULL;
3754 }
3755
3756 #ifdef ASSERT
3757 class VerifyCSetClosure: public HeapRegionClosure {
3758 public:
3759 bool doHeapRegion(HeapRegion* hr) {
3760 // Here we check that the CSet region's RSet is ready for parallel
3761 // iteration. The fields that we'll verify are only manipulated
3762 // when the region is part of a CSet and is collected. Afterwards,
3763 // we reset these fields when we clear the region's RSet (when the
3764 // region is freed) so they are ready when the region is
3765 // re-allocated. The only exception to this is if there's an
3766 // evacuation failure and instead of freeing the region we leave
3767 // it in the heap. In that case, we reset these fields during
3768 // evacuation failure handling.
3769 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3770
3771 // Here's a good place to add any other checks we'd like to
3772 // perform on CSet regions.
3773 return false;
3774 }
3775 };
3776 #endif // ASSERT
3777
3778 #if TASKQUEUE_STATS
3779 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3780 st->print_raw_cr("GC Task Stats");
3781 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3782 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3783 }
3784
3785 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3786 print_taskqueue_stats_hdr(st);
3787
3788 TaskQueueStats totals;
3789 const int n = workers() != NULL ? workers()->total_workers() : 1;
3790 for (int i = 0; i < n; ++i) {
3791 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3792 totals += task_queue(i)->stats;
3793 }
3794 st->print_raw("tot "); totals.print(st); st->cr();
3795
3796 DEBUG_ONLY(totals.verify());
3797 }
3798
3799 void G1CollectedHeap::reset_taskqueue_stats() {
3800 const int n = workers() != NULL ? workers()->total_workers() : 1;
3801 for (int i = 0; i < n; ++i) {
3802 task_queue(i)->stats.reset();
3803 }
3804 }
3805 #endif // TASKQUEUE_STATS
3806
3807 void G1CollectedHeap::log_gc_header() {
3808 if (!G1Log::fine()) {
3809 return;
3810 }
3811
3812 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3813
3814 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3815 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3816 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3817
3818 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3819 }
3820
3821 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3822 if (!G1Log::fine()) {
3823 return;
3824 }
3825
3826 if (G1Log::finer()) {
3827 if (evacuation_failed()) {
3828 gclog_or_tty->print(" (to-space exhausted)");
3829 }
3830 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3831 g1_policy()->phase_times()->note_gc_end();
3832 g1_policy()->phase_times()->print(pause_time_sec);
3833 g1_policy()->print_detailed_heap_transition();
3834 } else {
3835 if (evacuation_failed()) {
3836 gclog_or_tty->print("--");
3837 }
3838 g1_policy()->print_heap_transition();
3839 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3840 }
3841 gclog_or_tty->flush();
3842 }
3843
3844 bool
3845 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3846 assert_at_safepoint(true /* should_be_vm_thread */);
3847 guarantee(!is_gc_active(), "collection is not reentrant");
3848
3849 if (GC_locker::check_active_before_gc()) {
3850 return false;
3851 }
3852
3853 _gc_timer_stw->register_gc_start();
3854
3855 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3856
3857 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3858 ResourceMark rm;
3859
3860 print_heap_before_gc();
3861 trace_heap_before_gc(_gc_tracer_stw);
3862
3863 verify_region_sets_optional();
3864 verify_dirty_young_regions();
3865
3866 // This call will decide whether this pause is an initial-mark
3867 // pause. If it is, during_initial_mark_pause() will return true
3868 // for the duration of this pause.
3869 g1_policy()->decide_on_conc_mark_initiation();
3870
3871 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3872 assert(!g1_policy()->during_initial_mark_pause() ||
3873 g1_policy()->gcs_are_young(), "sanity");
3874
3875 // We also do not allow mixed GCs during marking.
3876 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3877
3878 // Record whether this pause is an initial mark. When the current
3879 // thread has completed its logging output and it's safe to signal
3880 // the CM thread, the flag's value in the policy has been reset.
3881 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3882
3883 // Inner scope for scope based logging, timers, and stats collection
3884 {
3885 EvacuationInfo evacuation_info;
3886
3887 if (g1_policy()->during_initial_mark_pause()) {
3888 // We are about to start a marking cycle, so we increment the
3889 // full collection counter.
3890 increment_old_marking_cycles_started();
3891 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3892 }
3893
3894 _gc_tracer_stw->report_yc_type(yc_type());
3895
3896 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3897
3898 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3899 workers()->active_workers() : 1);
3900 double pause_start_sec = os::elapsedTime();
3901 g1_policy()->phase_times()->note_gc_start(active_workers);
3902 log_gc_header();
3903
3904 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3905 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3906
3907 // If the secondary_free_list is not empty, append it to the
3908 // free_list. No need to wait for the cleanup operation to finish;
3909 // the region allocation code will check the secondary_free_list
3910 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3911 // set, skip this step so that the region allocation code has to
3912 // get entries from the secondary_free_list.
3913 if (!G1StressConcRegionFreeing) {
3914 append_secondary_free_list_if_not_empty_with_lock();
3915 }
3916
3917 assert(check_young_list_well_formed(), "young list should be well formed");
3918 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3919 "sanity check");
3920
3921 // Don't dynamically change the number of GC threads this early. A value of
3922 // 0 is used to indicate serial work. When parallel work is done,
3923 // it will be set.
3924
3925 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3926 IsGCActiveMark x;
3927
3928 gc_prologue(false);
3929 increment_total_collections(false /* full gc */);
3930 increment_gc_time_stamp();
3931
3932 verify_before_gc();
3933 check_bitmaps("GC Start");
3934
3935 COMPILER2_PRESENT(DerivedPointerTable::clear());
3936
3937 // Please see comment in g1CollectedHeap.hpp and
3938 // G1CollectedHeap::ref_processing_init() to see how
3939 // reference processing currently works in G1.
3940
3941 // Enable discovery in the STW reference processor
3942 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3943 true /*verify_no_refs*/);
3944
3945 {
3946 // We want to temporarily turn off discovery by the
3947 // CM ref processor, if necessary, and turn it back on
3948 // on again later if we do. Using a scoped
3949 // NoRefDiscovery object will do this.
3950 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3951
3952 // Forget the current alloc region (we might even choose it to be part
3953 // of the collection set!).
3954 _allocator->release_mutator_alloc_region();
3955
3956 // We should call this after we retire the mutator alloc
3957 // region(s) so that all the ALLOC / RETIRE events are generated
3958 // before the start GC event.
3959 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3960
3961 // This timing is only used by the ergonomics to handle our pause target.
3962 // It is unclear why this should not include the full pause. We will
3963 // investigate this in CR 7178365.
3964 //
3965 // Preserving the old comment here if that helps the investigation:
3966 //
3967 // The elapsed time induced by the start time below deliberately elides
3968 // the possible verification above.
3969 double sample_start_time_sec = os::elapsedTime();
3970
3971 #if YOUNG_LIST_VERBOSE
3972 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3973 _young_list->print();
3974 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3975 #endif // YOUNG_LIST_VERBOSE
3976
3977 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3978
3979 double scan_wait_start = os::elapsedTime();
3980 // We have to wait until the CM threads finish scanning the
3981 // root regions as it's the only way to ensure that all the
3982 // objects on them have been correctly scanned before we start
3983 // moving them during the GC.
3984 bool waited = _cm->root_regions()->wait_until_scan_finished();
3985 double wait_time_ms = 0.0;
3986 if (waited) {
3987 double scan_wait_end = os::elapsedTime();
3988 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3989 }
3990 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3991
3992 #if YOUNG_LIST_VERBOSE
3993 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3994 _young_list->print();
3995 #endif // YOUNG_LIST_VERBOSE
3996
3997 if (g1_policy()->during_initial_mark_pause()) {
3998 concurrent_mark()->checkpointRootsInitialPre();
3999 }
4000
4001 #if YOUNG_LIST_VERBOSE
4002 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4003 _young_list->print();
4004 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4005 #endif // YOUNG_LIST_VERBOSE
4006
4007 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4008
4009 register_humongous_regions_with_in_cset_fast_test();
4010
4011 _cm->note_start_of_gc();
4012 // We should not verify the per-thread SATB buffers given that
4013 // we have not filtered them yet (we'll do so during the
4014 // GC). We also call this after finalize_cset() to
4015 // ensure that the CSet has been finalized.
4016 _cm->verify_no_cset_oops(true /* verify_stacks */,
4017 true /* verify_enqueued_buffers */,
4018 false /* verify_thread_buffers */,
4019 true /* verify_fingers */);
4020
4021 if (_hr_printer.is_active()) {
4022 HeapRegion* hr = g1_policy()->collection_set();
4023 while (hr != NULL) {
4024 G1HRPrinter::RegionType type;
4025 if (!hr->is_young()) {
4026 type = G1HRPrinter::Old;
4027 } else if (hr->is_survivor()) {
4028 type = G1HRPrinter::Survivor;
4029 } else {
4030 type = G1HRPrinter::Eden;
4031 }
4032 _hr_printer.cset(hr);
4033 hr = hr->next_in_collection_set();
4034 }
4035 }
4036
4037 #ifdef ASSERT
4038 VerifyCSetClosure cl;
4039 collection_set_iterate(&cl);
4040 #endif // ASSERT
4041
4042 setup_surviving_young_words();
4043
4044 // Initialize the GC alloc regions.
4045 _allocator->init_gc_alloc_regions(evacuation_info);
4046
4047 // Actually do the work...
4048 evacuate_collection_set(evacuation_info);
4049
4050 // We do this to mainly verify the per-thread SATB buffers
4051 // (which have been filtered by now) since we didn't verify
4052 // them earlier. No point in re-checking the stacks / enqueued
4053 // buffers given that the CSet has not changed since last time
4054 // we checked.
4055 _cm->verify_no_cset_oops(false /* verify_stacks */,
4056 false /* verify_enqueued_buffers */,
4057 true /* verify_thread_buffers */,
4058 true /* verify_fingers */);
4059
4060 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4061
4062 eagerly_reclaim_humongous_regions();
4063
4064 g1_policy()->clear_collection_set();
4065
4066 cleanup_surviving_young_words();
4067
4068 // Start a new incremental collection set for the next pause.
4069 g1_policy()->start_incremental_cset_building();
4070
4071 clear_cset_fast_test();
4072
4073 _young_list->reset_sampled_info();
4074
4075 // Don't check the whole heap at this point as the
4076 // GC alloc regions from this pause have been tagged
4077 // as survivors and moved on to the survivor list.
4078 // Survivor regions will fail the !is_young() check.
4079 assert(check_young_list_empty(false /* check_heap */),
4080 "young list should be empty");
4081
4082 #if YOUNG_LIST_VERBOSE
4083 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4084 _young_list->print();
4085 #endif // YOUNG_LIST_VERBOSE
4086
4087 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4088 _young_list->first_survivor_region(),
4089 _young_list->last_survivor_region());
4090
4091 _young_list->reset_auxilary_lists();
4092
4093 if (evacuation_failed()) {
4094 _allocator->set_used(recalculate_used());
4095 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4096 for (uint i = 0; i < n_queues; i++) {
4097 if (_evacuation_failed_info_array[i].has_failed()) {
4098 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4099 }
4100 }
4101 } else {
4102 // The "used" of the the collection set have already been subtracted
4103 // when they were freed. Add in the bytes evacuated.
4104 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4105 }
4106
4107 if (g1_policy()->during_initial_mark_pause()) {
4108 // We have to do this before we notify the CM threads that
4109 // they can start working to make sure that all the
4110 // appropriate initialization is done on the CM object.
4111 concurrent_mark()->checkpointRootsInitialPost();
4112 set_marking_started();
4113 // Note that we don't actually trigger the CM thread at
4114 // this point. We do that later when we're sure that
4115 // the current thread has completed its logging output.
4116 }
4117
4118 allocate_dummy_regions();
4119
4120 #if YOUNG_LIST_VERBOSE
4121 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4122 _young_list->print();
4123 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4124 #endif // YOUNG_LIST_VERBOSE
4125
4126 _allocator->init_mutator_alloc_region();
4127
4128 {
4129 size_t expand_bytes = g1_policy()->expansion_amount();
4130 if (expand_bytes > 0) {
4131 size_t bytes_before = capacity();
4132 // No need for an ergo verbose message here,
4133 // expansion_amount() does this when it returns a value > 0.
4134 if (!expand(expand_bytes)) {
4135 // We failed to expand the heap. Cannot do anything about it.
4136 }
4137 }
4138 }
4139
4140 // We redo the verification but now wrt to the new CSet which
4141 // has just got initialized after the previous CSet was freed.
4142 _cm->verify_no_cset_oops(true /* verify_stacks */,
4143 true /* verify_enqueued_buffers */,
4144 true /* verify_thread_buffers */,
4145 true /* verify_fingers */);
4146 _cm->note_end_of_gc();
4147
4148 // This timing is only used by the ergonomics to handle our pause target.
4149 // It is unclear why this should not include the full pause. We will
4150 // investigate this in CR 7178365.
4151 double sample_end_time_sec = os::elapsedTime();
4152 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4153 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4154
4155 MemoryService::track_memory_usage();
4156
4157 // In prepare_for_verify() below we'll need to scan the deferred
4158 // update buffers to bring the RSets up-to-date if
4159 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4160 // the update buffers we'll probably need to scan cards on the
4161 // regions we just allocated to (i.e., the GC alloc
4162 // regions). However, during the last GC we called
4163 // set_saved_mark() on all the GC alloc regions, so card
4164 // scanning might skip the [saved_mark_word()...top()] area of
4165 // those regions (i.e., the area we allocated objects into
4166 // during the last GC). But it shouldn't. Given that
4167 // saved_mark_word() is conditional on whether the GC time stamp
4168 // on the region is current or not, by incrementing the GC time
4169 // stamp here we invalidate all the GC time stamps on all the
4170 // regions and saved_mark_word() will simply return top() for
4171 // all the regions. This is a nicer way of ensuring this rather
4172 // than iterating over the regions and fixing them. In fact, the
4173 // GC time stamp increment here also ensures that
4174 // saved_mark_word() will return top() between pauses, i.e.,
4175 // during concurrent refinement. So we don't need the
4176 // is_gc_active() check to decided which top to use when
4177 // scanning cards (see CR 7039627).
4178 increment_gc_time_stamp();
4179
4180 verify_after_gc();
4181 check_bitmaps("GC End");
4182
4183 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4184 ref_processor_stw()->verify_no_references_recorded();
4185
4186 // CM reference discovery will be re-enabled if necessary.
4187 }
4188
4189 // We should do this after we potentially expand the heap so
4190 // that all the COMMIT events are generated before the end GC
4191 // event, and after we retire the GC alloc regions so that all
4192 // RETIRE events are generated before the end GC event.
4193 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4194
4195 #ifdef TRACESPINNING
4196 ParallelTaskTerminator::print_termination_counts();
4197 #endif
4198
4199 gc_epilogue(false);
4200 }
4201
4202 // Print the remainder of the GC log output.
4203 log_gc_footer(os::elapsedTime() - pause_start_sec);
4204
4205 // It is not yet to safe to tell the concurrent mark to
4206 // start as we have some optional output below. We don't want the
4207 // output from the concurrent mark thread interfering with this
4208 // logging output either.
4209
4210 _hrm.verify_optional();
4211 verify_region_sets_optional();
4212
4213 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4214 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4215
4216 print_heap_after_gc();
4217 trace_heap_after_gc(_gc_tracer_stw);
4218
4219 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4220 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4221 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4222 // before any GC notifications are raised.
4223 g1mm()->update_sizes();
4224
4225 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4226 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4227 _gc_timer_stw->register_gc_end();
4228 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4229 }
4230 // It should now be safe to tell the concurrent mark thread to start
4231 // without its logging output interfering with the logging output
4232 // that came from the pause.
4233
4234 if (should_start_conc_mark) {
4235 // CAUTION: after the doConcurrentMark() call below,
4236 // the concurrent marking thread(s) could be running
4237 // concurrently with us. Make sure that anything after
4238 // this point does not assume that we are the only GC thread
4239 // running. Note: of course, the actual marking work will
4240 // not start until the safepoint itself is released in
4241 // SuspendibleThreadSet::desynchronize().
4242 doConcurrentMark();
4243 }
4244
4245 return true;
4246 }
4247
4248 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4249 {
4250 size_t gclab_word_size;
4251 switch (purpose) {
4252 case GCAllocForSurvived:
4253 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4254 break;
4255 case GCAllocForTenured:
4256 gclab_word_size = _old_plab_stats.desired_plab_sz();
4257 break;
4258 default:
4259 assert(false, "unknown GCAllocPurpose");
4260 gclab_word_size = _old_plab_stats.desired_plab_sz();
4261 break;
4262 }
4263
4264 // Prevent humongous PLAB sizes for two reasons:
4265 // * PLABs are allocated using a similar paths as oops, but should
4266 // never be in a humongous region
4267 // * Allowing humongous PLABs needlessly churns the region free lists
4268 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4269 }
4270
4271 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4272 _drain_in_progress = false;
4273 set_evac_failure_closure(cl);
4274 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4275 }
4276
4277 void G1CollectedHeap::finalize_for_evac_failure() {
4278 assert(_evac_failure_scan_stack != NULL &&
4279 _evac_failure_scan_stack->length() == 0,
4280 "Postcondition");
4281 assert(!_drain_in_progress, "Postcondition");
4282 delete _evac_failure_scan_stack;
4283 _evac_failure_scan_stack = NULL;
4284 }
4285
4286 void G1CollectedHeap::remove_self_forwarding_pointers() {
4287 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4288
4289 double remove_self_forwards_start = os::elapsedTime();
4290
4291 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4292
4293 if (G1CollectedHeap::use_parallel_gc_threads()) {
4294 set_par_threads();
4295 workers()->run_task(&rsfp_task);
4296 set_par_threads(0);
4297 } else {
4298 rsfp_task.work(0);
4299 }
4300
4301 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4302
4303 // Reset the claim values in the regions in the collection set.
4304 reset_cset_heap_region_claim_values();
4305
4306 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4307
4308 // Now restore saved marks, if any.
4309 assert(_objs_with_preserved_marks.size() ==
4310 _preserved_marks_of_objs.size(), "Both or none.");
4311 while (!_objs_with_preserved_marks.is_empty()) {
4312 oop obj = _objs_with_preserved_marks.pop();
4313 markOop m = _preserved_marks_of_objs.pop();
4314 obj->set_mark(m);
4315 }
4316 _objs_with_preserved_marks.clear(true);
4317 _preserved_marks_of_objs.clear(true);
4318
4319 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4320 }
4321
4322 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4323 _evac_failure_scan_stack->push(obj);
4324 }
4325
4326 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4327 assert(_evac_failure_scan_stack != NULL, "precondition");
4328
4329 while (_evac_failure_scan_stack->length() > 0) {
4330 oop obj = _evac_failure_scan_stack->pop();
4331 _evac_failure_closure->set_region(heap_region_containing(obj));
4332 obj->oop_iterate_backwards(_evac_failure_closure);
4333 }
4334 }
4335
4336 oop
4337 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4338 oop old) {
4339 assert(obj_in_cs(old),
4340 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4341 (HeapWord*) old));
4342 markOop m = old->mark();
4343 oop forward_ptr = old->forward_to_atomic(old);
4344 if (forward_ptr == NULL) {
4345 // Forward-to-self succeeded.
4346 assert(_par_scan_state != NULL, "par scan state");
4347 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4348 uint queue_num = _par_scan_state->queue_num();
4349
4350 _evacuation_failed = true;
4351 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4352 if (_evac_failure_closure != cl) {
4353 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4354 assert(!_drain_in_progress,
4355 "Should only be true while someone holds the lock.");
4356 // Set the global evac-failure closure to the current thread's.
4357 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4358 set_evac_failure_closure(cl);
4359 // Now do the common part.
4360 handle_evacuation_failure_common(old, m);
4361 // Reset to NULL.
4362 set_evac_failure_closure(NULL);
4363 } else {
4364 // The lock is already held, and this is recursive.
4365 assert(_drain_in_progress, "This should only be the recursive case.");
4366 handle_evacuation_failure_common(old, m);
4367 }
4368 return old;
4369 } else {
4370 // Forward-to-self failed. Either someone else managed to allocate
4371 // space for this object (old != forward_ptr) or they beat us in
4372 // self-forwarding it (old == forward_ptr).
4373 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4374 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4375 "should not be in the CSet",
4376 (HeapWord*) old, (HeapWord*) forward_ptr));
4377 return forward_ptr;
4378 }
4379 }
4380
4381 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4382 preserve_mark_if_necessary(old, m);
4383
4384 HeapRegion* r = heap_region_containing(old);
4385 if (!r->evacuation_failed()) {
4386 r->set_evacuation_failed(true);
4387 _hr_printer.evac_failure(r);
4388 }
4389
4390 push_on_evac_failure_scan_stack(old);
4391
4392 if (!_drain_in_progress) {
4393 // prevent recursion in copy_to_survivor_space()
4394 _drain_in_progress = true;
4395 drain_evac_failure_scan_stack();
4396 _drain_in_progress = false;
4397 }
4398 }
4399
4400 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4401 assert(evacuation_failed(), "Oversaving!");
4402 // We want to call the "for_promotion_failure" version only in the
4403 // case of a promotion failure.
4404 if (m->must_be_preserved_for_promotion_failure(obj)) {
4405 _objs_with_preserved_marks.push(obj);
4406 _preserved_marks_of_objs.push(m);
4407 }
4408 }
4409
4410 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4411 size_t word_size,
4412 AllocationContext_t context) {
4413 if (purpose == GCAllocForSurvived) {
4414 HeapWord* result = survivor_attempt_allocation(word_size, context);
4415 if (result != NULL) {
4416 return result;
4417 } else {
4418 // Let's try to allocate in the old gen in case we can fit the
4419 // object there.
4420 return old_attempt_allocation(word_size, context);
4421 }
4422 } else {
4423 assert(purpose == GCAllocForTenured, "sanity");
4424 HeapWord* result = old_attempt_allocation(word_size, context);
4425 if (result != NULL) {
4426 return result;
4427 } else {
4428 // Let's try to allocate in the survivors in case we can fit the
4429 // object there.
4430 return survivor_attempt_allocation(word_size, context);
4431 }
4432 }
4433
4434 ShouldNotReachHere();
4435 // Trying to keep some compilers happy.
4436 return NULL;
4437 }
4438
4439 void G1ParCopyHelper::mark_object(oop obj) {
4440 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4441
4442 // We know that the object is not moving so it's safe to read its size.
4443 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4444 }
4445
4446 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4447 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4448 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4449 assert(from_obj != to_obj, "should not be self-forwarded");
4450
4451 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4452 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4453
4454 // The object might be in the process of being copied by another
4455 // worker so we cannot trust that its to-space image is
4456 // well-formed. So we have to read its size from its from-space
4457 // image which we know should not be changing.
4458 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4459 }
4460
4461 template <class T>
4462 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4463 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4464 _scanned_klass->record_modified_oops();
4465 }
4466 }
4467
4468 template <G1Barrier barrier, G1Mark do_mark_object>
4469 template <class T>
4470 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4471 T heap_oop = oopDesc::load_heap_oop(p);
4472
4473 if (oopDesc::is_null(heap_oop)) {
4474 return;
4475 }
4476
4477 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4478
4479 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4480
4481 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4482
4483 if (state == G1CollectedHeap::InCSet) {
4484 oop forwardee;
4485 if (obj->is_forwarded()) {
4486 forwardee = obj->forwardee();
4487 } else {
4488 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4489 }
4490 assert(forwardee != NULL, "forwardee should not be NULL");
4491 oopDesc::encode_store_heap_oop(p, forwardee);
4492 if (do_mark_object != G1MarkNone && forwardee != obj) {
4493 // If the object is self-forwarded we don't need to explicitly
4494 // mark it, the evacuation failure protocol will do so.
4495 mark_forwarded_object(obj, forwardee);
4496 }
4497
4498 if (barrier == G1BarrierKlass) {
4499 do_klass_barrier(p, forwardee);
4500 }
4501 } else {
4502 if (state == G1CollectedHeap::IsHumongous) {
4503 _g1->set_humongous_is_live(obj);
4504 }
4505 // The object is not in collection set. If we're a root scanning
4506 // closure during an initial mark pause then attempt to mark the object.
4507 if (do_mark_object == G1MarkFromRoot) {
4508 mark_object(obj);
4509 }
4510 }
4511
4512 if (barrier == G1BarrierEvac) {
4513 _par_scan_state->update_rs(_from, p, _worker_id);
4514 }
4515 }
4516
4517 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4518 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4519
4520 class G1ParEvacuateFollowersClosure : public VoidClosure {
4521 protected:
4522 G1CollectedHeap* _g1h;
4523 G1ParScanThreadState* _par_scan_state;
4524 RefToScanQueueSet* _queues;
4525 ParallelTaskTerminator* _terminator;
4526
4527 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4528 RefToScanQueueSet* queues() { return _queues; }
4529 ParallelTaskTerminator* terminator() { return _terminator; }
4530
4531 public:
4532 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4533 G1ParScanThreadState* par_scan_state,
4534 RefToScanQueueSet* queues,
4535 ParallelTaskTerminator* terminator)
4536 : _g1h(g1h), _par_scan_state(par_scan_state),
4537 _queues(queues), _terminator(terminator) {}
4538
4539 void do_void();
4540
4541 private:
4542 inline bool offer_termination();
4543 };
4544
4545 bool G1ParEvacuateFollowersClosure::offer_termination() {
4546 G1ParScanThreadState* const pss = par_scan_state();
4547 pss->start_term_time();
4548 const bool res = terminator()->offer_termination();
4549 pss->end_term_time();
4550 return res;
4551 }
4552
4553 void G1ParEvacuateFollowersClosure::do_void() {
4554 G1ParScanThreadState* const pss = par_scan_state();
4555 pss->trim_queue();
4556 do {
4557 pss->steal_and_trim_queue(queues());
4558 } while (!offer_termination());
4559 }
4560
4561 class G1KlassScanClosure : public KlassClosure {
4562 G1ParCopyHelper* _closure;
4563 bool _process_only_dirty;
4564 int _count;
4565 public:
4566 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4567 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4568 void do_klass(Klass* klass) {
4569 // If the klass has not been dirtied we know that there's
4570 // no references into the young gen and we can skip it.
4571 if (!_process_only_dirty || klass->has_modified_oops()) {
4572 // Clean the klass since we're going to scavenge all the metadata.
4573 klass->clear_modified_oops();
4574
4575 // Tell the closure that this klass is the Klass to scavenge
4576 // and is the one to dirty if oops are left pointing into the young gen.
4577 _closure->set_scanned_klass(klass);
4578
4579 klass->oops_do(_closure);
4580
4581 _closure->set_scanned_klass(NULL);
4582 }
4583 _count++;
4584 }
4585 };
4586
4587 class G1ParTask : public AbstractGangTask {
4588 protected:
4589 G1CollectedHeap* _g1h;
4590 RefToScanQueueSet *_queues;
4591 ParallelTaskTerminator _terminator;
4592 uint _n_workers;
4593
4594 Mutex _stats_lock;
4595 Mutex* stats_lock() { return &_stats_lock; }
4596
4597 public:
4598 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4599 : AbstractGangTask("G1 collection"),
4600 _g1h(g1h),
4601 _queues(task_queues),
4602 _terminator(0, _queues),
4603 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4604 {}
4605
4606 RefToScanQueueSet* queues() { return _queues; }
4607
4608 RefToScanQueue *work_queue(int i) {
4609 return queues()->queue(i);
4610 }
4611
4612 ParallelTaskTerminator* terminator() { return &_terminator; }
4613
4614 virtual void set_for_termination(int active_workers) {
4615 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4616 // in the young space (_par_seq_tasks) in the G1 heap
4617 // for SequentialSubTasksDone.
4618 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4619 // both of which need setting by set_n_termination().
4620 _g1h->SharedHeap::set_n_termination(active_workers);
4621 _g1h->set_n_termination(active_workers);
4622 terminator()->reset_for_reuse(active_workers);
4623 _n_workers = active_workers;
4624 }
4625
4626 // Helps out with CLD processing.
4627 //
4628 // During InitialMark we need to:
4629 // 1) Scavenge all CLDs for the young GC.
4630 // 2) Mark all objects directly reachable from strong CLDs.
4631 template <G1Mark do_mark_object>
4632 class G1CLDClosure : public CLDClosure {
4633 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4634 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4635 G1KlassScanClosure _klass_in_cld_closure;
4636 bool _claim;
4637
4638 public:
4639 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4640 bool only_young, bool claim)
4641 : _oop_closure(oop_closure),
4642 _oop_in_klass_closure(oop_closure->g1(),
4643 oop_closure->pss(),
4644 oop_closure->rp()),
4645 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4646 _claim(claim) {
4647
4648 }
4649
4650 void do_cld(ClassLoaderData* cld) {
4651 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4652 }
4653 };
4654
4655 class G1CodeBlobClosure: public CodeBlobClosure {
4656 OopClosure* _f;
4657
4658 public:
4659 G1CodeBlobClosure(OopClosure* f) : _f(f) {}
4660 void do_code_blob(CodeBlob* blob) {
4661 nmethod* that = blob->as_nmethod_or_null();
4662 if (that != NULL) {
4663 if (!that->test_set_oops_do_mark()) {
4664 that->oops_do(_f);
4665 that->fix_oop_relocations();
4666 }
4667 }
4668 }
4669 };
4670
4671 void work(uint worker_id) {
4672 if (worker_id >= _n_workers) return; // no work needed this round
4673
4674 double start_time_ms = os::elapsedTime() * 1000.0;
4675 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4676
4677 {
4678 ResourceMark rm;
4679 HandleMark hm;
4680
4681 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4682
4683 G1ParScanThreadState pss(_g1h, worker_id, rp);
4684 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4685
4686 pss.set_evac_failure_closure(&evac_failure_cl);
4687
4688 bool only_young = _g1h->g1_policy()->gcs_are_young();
4689
4690 // Non-IM young GC.
4691 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4692 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4693 only_young, // Only process dirty klasses.
4694 false); // No need to claim CLDs.
4695 // IM young GC.
4696 // Strong roots closures.
4697 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4698 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4699 false, // Process all klasses.
4700 true); // Need to claim CLDs.
4701 // Weak roots closures.
4702 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4703 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4704 false, // Process all klasses.
4705 true); // Need to claim CLDs.
4706
4707 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4708 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4709 // IM Weak code roots are handled later.
4710
4711 OopClosure* strong_root_cl;
4712 OopClosure* weak_root_cl;
4713 CLDClosure* strong_cld_cl;
4714 CLDClosure* weak_cld_cl;
4715 CodeBlobClosure* strong_code_cl;
4716
4717 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4718 // We also need to mark copied objects.
4719 strong_root_cl = &scan_mark_root_cl;
4720 strong_cld_cl = &scan_mark_cld_cl;
4721 strong_code_cl = &scan_mark_code_cl;
4722 if (ClassUnloadingWithConcurrentMark) {
4723 weak_root_cl = &scan_mark_weak_root_cl;
4724 weak_cld_cl = &scan_mark_weak_cld_cl;
4725 } else {
4726 weak_root_cl = &scan_mark_root_cl;
4727 weak_cld_cl = &scan_mark_cld_cl;
4728 }
4729 } else {
4730 strong_root_cl = &scan_only_root_cl;
4731 weak_root_cl = &scan_only_root_cl;
4732 strong_cld_cl = &scan_only_cld_cl;
4733 weak_cld_cl = &scan_only_cld_cl;
4734 strong_code_cl = &scan_only_code_cl;
4735 }
4736
4737
4738 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4739
4740 pss.start_strong_roots();
4741 _g1h->g1_process_roots(strong_root_cl,
4742 weak_root_cl,
4743 &push_heap_rs_cl,
4744 strong_cld_cl,
4745 weak_cld_cl,
4746 strong_code_cl,
4747 worker_id);
4748
4749 pss.end_strong_roots();
4750
4751 {
4752 double start = os::elapsedTime();
4753 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4754 evac.do_void();
4755 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4756 double term_ms = pss.term_time()*1000.0;
4757 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4758 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4759 }
4760 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4761 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4762
4763 if (ParallelGCVerbose) {
4764 MutexLocker x(stats_lock());
4765 pss.print_termination_stats(worker_id);
4766 }
4767
4768 assert(pss.queue_is_empty(), "should be empty");
4769
4770 // Close the inner scope so that the ResourceMark and HandleMark
4771 // destructors are executed here and are included as part of the
4772 // "GC Worker Time".
4773 }
4774
4775 double end_time_ms = os::elapsedTime() * 1000.0;
4776 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4777 }
4778 };
4779
4780 // *** Common G1 Evacuation Stuff
4781
4782 // This method is run in a GC worker.
4783
4784 void
4785 G1CollectedHeap::
4786 g1_process_roots(OopClosure* scan_non_heap_roots,
4787 OopClosure* scan_non_heap_weak_roots,
4788 OopsInHeapRegionClosure* scan_rs,
4789 CLDClosure* scan_strong_clds,
4790 CLDClosure* scan_weak_clds,
4791 CodeBlobClosure* scan_strong_code,
4792 uint worker_i) {
4793
4794 // First scan the shared roots.
4795 double ext_roots_start = os::elapsedTime();
4796 double closure_app_time_sec = 0.0;
4797
4798 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4799 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4800
4801 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4802 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4803
4804 process_roots(false, // no scoping; this is parallel code
4805 SharedHeap::SO_None,
4806 &buf_scan_non_heap_roots,
4807 &buf_scan_non_heap_weak_roots,
4808 scan_strong_clds,
4809 // Unloading Initial Marks handle the weak CLDs separately.
4810 (trace_metadata ? NULL : scan_weak_clds),
4811 scan_strong_code);
4812
4813 // Now the CM ref_processor roots.
4814 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4815 // We need to treat the discovered reference lists of the
4816 // concurrent mark ref processor as roots and keep entries
4817 // (which are added by the marking threads) on them live
4818 // until they can be processed at the end of marking.
4819 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4820 }
4821
4822 if (trace_metadata) {
4823 // Barrier to make sure all workers passed
4824 // the strong CLD and strong nmethods phases.
4825 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4826
4827 // Now take the complement of the strong CLDs.
4828 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4829 }
4830
4831 // Finish up any enqueued closure apps (attributed as object copy time).
4832 buf_scan_non_heap_roots.done();
4833 buf_scan_non_heap_weak_roots.done();
4834
4835 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4836 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4837
4838 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4839
4840 double ext_root_time_ms =
4841 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4842
4843 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4844
4845 // During conc marking we have to filter the per-thread SATB buffers
4846 // to make sure we remove any oops into the CSet (which will show up
4847 // as implicitly live).
4848 double satb_filtering_ms = 0.0;
4849 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4850 if (mark_in_progress()) {
4851 double satb_filter_start = os::elapsedTime();
4852
4853 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4854
4855 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4856 }
4857 }
4858 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4859
4860 // Now scan the complement of the collection set.
4861 MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations);
4862
4863 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4864
4865 _process_strong_tasks->all_tasks_completed();
4866 }
4867
4868 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4869 private:
4870 BoolObjectClosure* _is_alive;
4871 int _initial_string_table_size;
4872 int _initial_symbol_table_size;
4873
4874 bool _process_strings;
4875 int _strings_processed;
4876 int _strings_removed;
4877
4878 bool _process_symbols;
4879 int _symbols_processed;
4880 int _symbols_removed;
4881
4882 bool _do_in_parallel;
4883 public:
4884 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4885 AbstractGangTask("String/Symbol Unlinking"),
4886 _is_alive(is_alive),
4887 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4888 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4889 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4890
4891 _initial_string_table_size = StringTable::the_table()->table_size();
4892 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4893 if (process_strings) {
4894 StringTable::clear_parallel_claimed_index();
4895 }
4896 if (process_symbols) {
4897 SymbolTable::clear_parallel_claimed_index();
4898 }
4899 }
4900
4901 ~G1StringSymbolTableUnlinkTask() {
4902 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4903 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4904 StringTable::parallel_claimed_index(), _initial_string_table_size));
4905 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4906 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4907 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4908
4909 if (G1TraceStringSymbolTableScrubbing) {
4910 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4911 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4912 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4913 strings_processed(), strings_removed(),
4914 symbols_processed(), symbols_removed());
4915 }
4916 }
4917
4918 void work(uint worker_id) {
4919 if (_do_in_parallel) {
4920 int strings_processed = 0;
4921 int strings_removed = 0;
4922 int symbols_processed = 0;
4923 int symbols_removed = 0;
4924 if (_process_strings) {
4925 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4926 Atomic::add(strings_processed, &_strings_processed);
4927 Atomic::add(strings_removed, &_strings_removed);
4928 }
4929 if (_process_symbols) {
4930 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4931 Atomic::add(symbols_processed, &_symbols_processed);
4932 Atomic::add(symbols_removed, &_symbols_removed);
4933 }
4934 } else {
4935 if (_process_strings) {
4936 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
4937 }
4938 if (_process_symbols) {
4939 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
4940 }
4941 }
4942 }
4943
4944 size_t strings_processed() const { return (size_t)_strings_processed; }
4945 size_t strings_removed() const { return (size_t)_strings_removed; }
4946
4947 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4948 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4949 };
4950
4951 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4952 private:
4953 static Monitor* _lock;
4954
4955 BoolObjectClosure* const _is_alive;
4956 const bool _unloading_occurred;
4957 const uint _num_workers;
4958
4959 // Variables used to claim nmethods.
4960 nmethod* _first_nmethod;
4961 volatile nmethod* _claimed_nmethod;
4962
4963 // The list of nmethods that need to be processed by the second pass.
4964 volatile nmethod* _postponed_list;
4965 volatile uint _num_entered_barrier;
4966
4967 public:
4968 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4969 _is_alive(is_alive),
4970 _unloading_occurred(unloading_occurred),
4971 _num_workers(num_workers),
4972 _first_nmethod(NULL),
4973 _claimed_nmethod(NULL),
4974 _postponed_list(NULL),
4975 _num_entered_barrier(0)
4976 {
4977 nmethod::increase_unloading_clock();
4978 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
4979 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4980 }
4981
4982 ~G1CodeCacheUnloadingTask() {
4983 CodeCache::verify_clean_inline_caches();
4984
4985 CodeCache::set_needs_cache_clean(false);
4986 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4987
4988 CodeCache::verify_icholder_relocations();
4989 }
4990
4991 private:
4992 void add_to_postponed_list(nmethod* nm) {
4993 nmethod* old;
4994 do {
4995 old = (nmethod*)_postponed_list;
4996 nm->set_unloading_next(old);
4997 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4998 }
4999
5000 void clean_nmethod(nmethod* nm) {
5001 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
5002
5003 if (postponed) {
5004 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
5005 add_to_postponed_list(nm);
5006 }
5007
5008 // Mark that this thread has been cleaned/unloaded.
5009 // After this call, it will be safe to ask if this nmethod was unloaded or not.
5010 nm->set_unloading_clock(nmethod::global_unloading_clock());
5011 }
5012
5013 void clean_nmethod_postponed(nmethod* nm) {
5014 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
5015 }
5016
5017 static const int MaxClaimNmethods = 16;
5018
5019 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
5020 nmethod* first;
5021 nmethod* last;
5022
5023 do {
5024 *num_claimed_nmethods = 0;
5025
5026 first = last = (nmethod*)_claimed_nmethod;
5027
5028 if (first != NULL) {
5029 for (int i = 0; i < MaxClaimNmethods; i++) {
5030 last = CodeCache::alive_nmethod(CodeCache::next(last));
5031
5032 if (last == NULL) {
5033 break;
5034 }
5035
5036 claimed_nmethods[i] = last;
5037 (*num_claimed_nmethods)++;
5038 }
5039 }
5040
5041 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
5042 }
5043
5044 nmethod* claim_postponed_nmethod() {
5045 nmethod* claim;
5046 nmethod* next;
5047
5048 do {
5049 claim = (nmethod*)_postponed_list;
5050 if (claim == NULL) {
5051 return NULL;
5052 }
5053
5054 next = claim->unloading_next();
5055
5056 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
5057
5058 return claim;
5059 }
5060
5061 public:
5062 // Mark that we're done with the first pass of nmethod cleaning.
5063 void barrier_mark(uint worker_id) {
5064 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5065 _num_entered_barrier++;
5066 if (_num_entered_barrier == _num_workers) {
5067 ml.notify_all();
5068 }
5069 }
5070
5071 // See if we have to wait for the other workers to
5072 // finish their first-pass nmethod cleaning work.
5073 void barrier_wait(uint worker_id) {
5074 if (_num_entered_barrier < _num_workers) {
5075 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5076 while (_num_entered_barrier < _num_workers) {
5077 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5078 }
5079 }
5080 }
5081
5082 // Cleaning and unloading of nmethods. Some work has to be postponed
5083 // to the second pass, when we know which nmethods survive.
5084 void work_first_pass(uint worker_id) {
5085 // The first nmethods is claimed by the first worker.
5086 if (worker_id == 0 && _first_nmethod != NULL) {
5087 clean_nmethod(_first_nmethod);
5088 _first_nmethod = NULL;
5089 }
5090
5091 int num_claimed_nmethods;
5092 nmethod* claimed_nmethods[MaxClaimNmethods];
5093
5094 while (true) {
5095 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5096
5097 if (num_claimed_nmethods == 0) {
5098 break;
5099 }
5100
5101 for (int i = 0; i < num_claimed_nmethods; i++) {
5102 clean_nmethod(claimed_nmethods[i]);
5103 }
5104 }
5105 }
5106
5107 void work_second_pass(uint worker_id) {
5108 nmethod* nm;
5109 // Take care of postponed nmethods.
5110 while ((nm = claim_postponed_nmethod()) != NULL) {
5111 clean_nmethod_postponed(nm);
5112 }
5113 }
5114 };
5115
5116 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5117
5118 class G1KlassCleaningTask : public StackObj {
5119 BoolObjectClosure* _is_alive;
5120 volatile jint _clean_klass_tree_claimed;
5121 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5122
5123 public:
5124 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5125 _is_alive(is_alive),
5126 _clean_klass_tree_claimed(0),
5127 _klass_iterator() {
5128 }
5129
5130 private:
5131 bool claim_clean_klass_tree_task() {
5132 if (_clean_klass_tree_claimed) {
5133 return false;
5134 }
5135
5136 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5137 }
5138
5139 InstanceKlass* claim_next_klass() {
5140 Klass* klass;
5141 do {
5142 klass =_klass_iterator.next_klass();
5143 } while (klass != NULL && !klass->oop_is_instance());
5144
5145 return (InstanceKlass*)klass;
5146 }
5147
5148 public:
5149
5150 void clean_klass(InstanceKlass* ik) {
5151 ik->clean_implementors_list(_is_alive);
5152 ik->clean_method_data(_is_alive);
5153
5154 // G1 specific cleanup work that has
5155 // been moved here to be done in parallel.
5156 ik->clean_dependent_nmethods();
5157 }
5158
5159 void work() {
5160 ResourceMark rm;
5161
5162 // One worker will clean the subklass/sibling klass tree.
5163 if (claim_clean_klass_tree_task()) {
5164 Klass::clean_subklass_tree(_is_alive);
5165 }
5166
5167 // All workers will help cleaning the classes,
5168 InstanceKlass* klass;
5169 while ((klass = claim_next_klass()) != NULL) {
5170 clean_klass(klass);
5171 }
5172 }
5173 };
5174
5175 // To minimize the remark pause times, the tasks below are done in parallel.
5176 class G1ParallelCleaningTask : public AbstractGangTask {
5177 private:
5178 G1StringSymbolTableUnlinkTask _string_symbol_task;
5179 G1CodeCacheUnloadingTask _code_cache_task;
5180 G1KlassCleaningTask _klass_cleaning_task;
5181
5182 public:
5183 // The constructor is run in the VMThread.
5184 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5185 AbstractGangTask("Parallel Cleaning"),
5186 _string_symbol_task(is_alive, process_strings, process_symbols),
5187 _code_cache_task(num_workers, is_alive, unloading_occurred),
5188 _klass_cleaning_task(is_alive) {
5189 }
5190
5191 // The parallel work done by all worker threads.
5192 void work(uint worker_id) {
5193 // Do first pass of code cache cleaning.
5194 _code_cache_task.work_first_pass(worker_id);
5195
5196 // Let the threads mark that the first pass is done.
5197 _code_cache_task.barrier_mark(worker_id);
5198
5199 // Clean the Strings and Symbols.
5200 _string_symbol_task.work(worker_id);
5201
5202 // Wait for all workers to finish the first code cache cleaning pass.
5203 _code_cache_task.barrier_wait(worker_id);
5204
5205 // Do the second code cache cleaning work, which realize on
5206 // the liveness information gathered during the first pass.
5207 _code_cache_task.work_second_pass(worker_id);
5208
5209 // Clean all klasses that were not unloaded.
5210 _klass_cleaning_task.work();
5211 }
5212 };
5213
5214
5215 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5216 bool process_strings,
5217 bool process_symbols,
5218 bool class_unloading_occurred) {
5219 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5220 workers()->active_workers() : 1);
5221
5222 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5223 n_workers, class_unloading_occurred);
5224 if (G1CollectedHeap::use_parallel_gc_threads()) {
5225 set_par_threads(n_workers);
5226 workers()->run_task(&g1_unlink_task);
5227 set_par_threads(0);
5228 } else {
5229 g1_unlink_task.work(0);
5230 }
5231 }
5232
5233 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5234 bool process_strings, bool process_symbols) {
5235 {
5236 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5237 _g1h->workers()->active_workers() : 1);
5238 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5239 if (G1CollectedHeap::use_parallel_gc_threads()) {
5240 set_par_threads(n_workers);
5241 workers()->run_task(&g1_unlink_task);
5242 set_par_threads(0);
5243 } else {
5244 g1_unlink_task.work(0);
5245 }
5246 }
5247
5248 if (G1StringDedup::is_enabled()) {
5249 G1StringDedup::unlink(is_alive);
5250 }
5251 }
5252
5253 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5254 private:
5255 DirtyCardQueueSet* _queue;
5256 public:
5257 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5258
5259 virtual void work(uint worker_id) {
5260 double start_time = os::elapsedTime();
5261
5262 RedirtyLoggedCardTableEntryClosure cl;
5263 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5264 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5265 } else {
5266 _queue->apply_closure_to_all_completed_buffers(&cl);
5267 }
5268
5269 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5270 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5271 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5272 }
5273 };
5274
5275 void G1CollectedHeap::redirty_logged_cards() {
5276 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5277 double redirty_logged_cards_start = os::elapsedTime();
5278
5279 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5280 _g1h->workers()->active_workers() : 1);
5281
5282 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5283 dirty_card_queue_set().reset_for_par_iteration();
5284 if (use_parallel_gc_threads()) {
5285 set_par_threads(n_workers);
5286 workers()->run_task(&redirty_task);
5287 set_par_threads(0);
5288 } else {
5289 redirty_task.work(0);
5290 }
5291
5292 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5293 dcq.merge_bufferlists(&dirty_card_queue_set());
5294 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5295
5296 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5297 }
5298
5299 // Weak Reference Processing support
5300
5301 // An always "is_alive" closure that is used to preserve referents.
5302 // If the object is non-null then it's alive. Used in the preservation
5303 // of referent objects that are pointed to by reference objects
5304 // discovered by the CM ref processor.
5305 class G1AlwaysAliveClosure: public BoolObjectClosure {
5306 G1CollectedHeap* _g1;
5307 public:
5308 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5309 bool do_object_b(oop p) {
5310 if (p != NULL) {
5311 return true;
5312 }
5313 return false;
5314 }
5315 };
5316
5317 bool G1STWIsAliveClosure::do_object_b(oop p) {
5318 // An object is reachable if it is outside the collection set,
5319 // or is inside and copied.
5320 return !_g1->obj_in_cs(p) || p->is_forwarded();
5321 }
5322
5323 // Non Copying Keep Alive closure
5324 class G1KeepAliveClosure: public OopClosure {
5325 G1CollectedHeap* _g1;
5326 public:
5327 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5328 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5329 void do_oop(oop* p) {
5330 oop obj = *p;
5331
5332 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5333 if (obj == NULL || cset_state == G1CollectedHeap::InNeither) {
5334 return;
5335 }
5336 if (cset_state == G1CollectedHeap::InCSet) {
5337 assert( obj->is_forwarded(), "invariant" );
5338 *p = obj->forwardee();
5339 } else {
5340 assert(!obj->is_forwarded(), "invariant" );
5341 assert(cset_state == G1CollectedHeap::IsHumongous,
5342 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5343 _g1->set_humongous_is_live(obj);
5344 }
5345 }
5346 };
5347
5348 // Copying Keep Alive closure - can be called from both
5349 // serial and parallel code as long as different worker
5350 // threads utilize different G1ParScanThreadState instances
5351 // and different queues.
5352
5353 class G1CopyingKeepAliveClosure: public OopClosure {
5354 G1CollectedHeap* _g1h;
5355 OopClosure* _copy_non_heap_obj_cl;
5356 G1ParScanThreadState* _par_scan_state;
5357
5358 public:
5359 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5360 OopClosure* non_heap_obj_cl,
5361 G1ParScanThreadState* pss):
5362 _g1h(g1h),
5363 _copy_non_heap_obj_cl(non_heap_obj_cl),
5364 _par_scan_state(pss)
5365 {}
5366
5367 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5368 virtual void do_oop( oop* p) { do_oop_work(p); }
5369
5370 template <class T> void do_oop_work(T* p) {
5371 oop obj = oopDesc::load_decode_heap_oop(p);
5372
5373 if (_g1h->is_in_cset_or_humongous(obj)) {
5374 // If the referent object has been forwarded (either copied
5375 // to a new location or to itself in the event of an
5376 // evacuation failure) then we need to update the reference
5377 // field and, if both reference and referent are in the G1
5378 // heap, update the RSet for the referent.
5379 //
5380 // If the referent has not been forwarded then we have to keep
5381 // it alive by policy. Therefore we have copy the referent.
5382 //
5383 // If the reference field is in the G1 heap then we can push
5384 // on the PSS queue. When the queue is drained (after each
5385 // phase of reference processing) the object and it's followers
5386 // will be copied, the reference field set to point to the
5387 // new location, and the RSet updated. Otherwise we need to
5388 // use the the non-heap or metadata closures directly to copy
5389 // the referent object and update the pointer, while avoiding
5390 // updating the RSet.
5391
5392 if (_g1h->is_in_g1_reserved(p)) {
5393 _par_scan_state->push_on_queue(p);
5394 } else {
5395 assert(!Metaspace::contains((const void*)p),
5396 err_msg("Unexpectedly found a pointer from metadata: "
5397 PTR_FORMAT, p));
5398 _copy_non_heap_obj_cl->do_oop(p);
5399 }
5400 }
5401 }
5402 };
5403
5404 // Serial drain queue closure. Called as the 'complete_gc'
5405 // closure for each discovered list in some of the
5406 // reference processing phases.
5407
5408 class G1STWDrainQueueClosure: public VoidClosure {
5409 protected:
5410 G1CollectedHeap* _g1h;
5411 G1ParScanThreadState* _par_scan_state;
5412
5413 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5414
5415 public:
5416 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5417 _g1h(g1h),
5418 _par_scan_state(pss)
5419 { }
5420
5421 void do_void() {
5422 G1ParScanThreadState* const pss = par_scan_state();
5423 pss->trim_queue();
5424 }
5425 };
5426
5427 // Parallel Reference Processing closures
5428
5429 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5430 // processing during G1 evacuation pauses.
5431
5432 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5433 private:
5434 G1CollectedHeap* _g1h;
5435 RefToScanQueueSet* _queues;
5436 FlexibleWorkGang* _workers;
5437 int _active_workers;
5438
5439 public:
5440 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5441 FlexibleWorkGang* workers,
5442 RefToScanQueueSet *task_queues,
5443 int n_workers) :
5444 _g1h(g1h),
5445 _queues(task_queues),
5446 _workers(workers),
5447 _active_workers(n_workers)
5448 {
5449 assert(n_workers > 0, "shouldn't call this otherwise");
5450 }
5451
5452 // Executes the given task using concurrent marking worker threads.
5453 virtual void execute(ProcessTask& task);
5454 virtual void execute(EnqueueTask& task);
5455 };
5456
5457 // Gang task for possibly parallel reference processing
5458
5459 class G1STWRefProcTaskProxy: public AbstractGangTask {
5460 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5461 ProcessTask& _proc_task;
5462 G1CollectedHeap* _g1h;
5463 RefToScanQueueSet *_task_queues;
5464 ParallelTaskTerminator* _terminator;
5465
5466 public:
5467 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5468 G1CollectedHeap* g1h,
5469 RefToScanQueueSet *task_queues,
5470 ParallelTaskTerminator* terminator) :
5471 AbstractGangTask("Process reference objects in parallel"),
5472 _proc_task(proc_task),
5473 _g1h(g1h),
5474 _task_queues(task_queues),
5475 _terminator(terminator)
5476 {}
5477
5478 virtual void work(uint worker_id) {
5479 // The reference processing task executed by a single worker.
5480 ResourceMark rm;
5481 HandleMark hm;
5482
5483 G1STWIsAliveClosure is_alive(_g1h);
5484
5485 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5486 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5487
5488 pss.set_evac_failure_closure(&evac_failure_cl);
5489
5490 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5491
5492 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5493
5494 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5495
5496 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5497 // We also need to mark copied objects.
5498 copy_non_heap_cl = ©_mark_non_heap_cl;
5499 }
5500
5501 // Keep alive closure.
5502 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5503
5504 // Complete GC closure
5505 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5506
5507 // Call the reference processing task's work routine.
5508 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5509
5510 // Note we cannot assert that the refs array is empty here as not all
5511 // of the processing tasks (specifically phase2 - pp2_work) execute
5512 // the complete_gc closure (which ordinarily would drain the queue) so
5513 // the queue may not be empty.
5514 }
5515 };
5516
5517 // Driver routine for parallel reference processing.
5518 // Creates an instance of the ref processing gang
5519 // task and has the worker threads execute it.
5520 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5521 assert(_workers != NULL, "Need parallel worker threads.");
5522
5523 ParallelTaskTerminator terminator(_active_workers, _queues);
5524 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5525
5526 _g1h->set_par_threads(_active_workers);
5527 _workers->run_task(&proc_task_proxy);
5528 _g1h->set_par_threads(0);
5529 }
5530
5531 // Gang task for parallel reference enqueueing.
5532
5533 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5534 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5535 EnqueueTask& _enq_task;
5536
5537 public:
5538 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5539 AbstractGangTask("Enqueue reference objects in parallel"),
5540 _enq_task(enq_task)
5541 { }
5542
5543 virtual void work(uint worker_id) {
5544 _enq_task.work(worker_id);
5545 }
5546 };
5547
5548 // Driver routine for parallel reference enqueueing.
5549 // Creates an instance of the ref enqueueing gang
5550 // task and has the worker threads execute it.
5551
5552 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5553 assert(_workers != NULL, "Need parallel worker threads.");
5554
5555 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5556
5557 _g1h->set_par_threads(_active_workers);
5558 _workers->run_task(&enq_task_proxy);
5559 _g1h->set_par_threads(0);
5560 }
5561
5562 // End of weak reference support closures
5563
5564 // Abstract task used to preserve (i.e. copy) any referent objects
5565 // that are in the collection set and are pointed to by reference
5566 // objects discovered by the CM ref processor.
5567
5568 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5569 protected:
5570 G1CollectedHeap* _g1h;
5571 RefToScanQueueSet *_queues;
5572 ParallelTaskTerminator _terminator;
5573 uint _n_workers;
5574
5575 public:
5576 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5577 AbstractGangTask("ParPreserveCMReferents"),
5578 _g1h(g1h),
5579 _queues(task_queues),
5580 _terminator(workers, _queues),
5581 _n_workers(workers)
5582 { }
5583
5584 void work(uint worker_id) {
5585 ResourceMark rm;
5586 HandleMark hm;
5587
5588 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5589 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5590
5591 pss.set_evac_failure_closure(&evac_failure_cl);
5592
5593 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5594
5595 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5596
5597 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5598
5599 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5600
5601 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5602 // We also need to mark copied objects.
5603 copy_non_heap_cl = ©_mark_non_heap_cl;
5604 }
5605
5606 // Is alive closure
5607 G1AlwaysAliveClosure always_alive(_g1h);
5608
5609 // Copying keep alive closure. Applied to referent objects that need
5610 // to be copied.
5611 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5612
5613 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5614
5615 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5616 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5617
5618 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5619 // So this must be true - but assert just in case someone decides to
5620 // change the worker ids.
5621 assert(0 <= worker_id && worker_id < limit, "sanity");
5622 assert(!rp->discovery_is_atomic(), "check this code");
5623
5624 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5625 for (uint idx = worker_id; idx < limit; idx += stride) {
5626 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5627
5628 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5629 while (iter.has_next()) {
5630 // Since discovery is not atomic for the CM ref processor, we
5631 // can see some null referent objects.
5632 iter.load_ptrs(DEBUG_ONLY(true));
5633 oop ref = iter.obj();
5634
5635 // This will filter nulls.
5636 if (iter.is_referent_alive()) {
5637 iter.make_referent_alive();
5638 }
5639 iter.move_to_next();
5640 }
5641 }
5642
5643 // Drain the queue - which may cause stealing
5644 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5645 drain_queue.do_void();
5646 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5647 assert(pss.queue_is_empty(), "should be");
5648 }
5649 };
5650
5651 // Weak Reference processing during an evacuation pause (part 1).
5652 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5653 double ref_proc_start = os::elapsedTime();
5654
5655 ReferenceProcessor* rp = _ref_processor_stw;
5656 assert(rp->discovery_enabled(), "should have been enabled");
5657
5658 // Any reference objects, in the collection set, that were 'discovered'
5659 // by the CM ref processor should have already been copied (either by
5660 // applying the external root copy closure to the discovered lists, or
5661 // by following an RSet entry).
5662 //
5663 // But some of the referents, that are in the collection set, that these
5664 // reference objects point to may not have been copied: the STW ref
5665 // processor would have seen that the reference object had already
5666 // been 'discovered' and would have skipped discovering the reference,
5667 // but would not have treated the reference object as a regular oop.
5668 // As a result the copy closure would not have been applied to the
5669 // referent object.
5670 //
5671 // We need to explicitly copy these referent objects - the references
5672 // will be processed at the end of remarking.
5673 //
5674 // We also need to do this copying before we process the reference
5675 // objects discovered by the STW ref processor in case one of these
5676 // referents points to another object which is also referenced by an
5677 // object discovered by the STW ref processor.
5678
5679 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5680 no_of_gc_workers == workers()->active_workers(),
5681 "Need to reset active GC workers");
5682
5683 set_par_threads(no_of_gc_workers);
5684 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5685 no_of_gc_workers,
5686 _task_queues);
5687
5688 if (G1CollectedHeap::use_parallel_gc_threads()) {
5689 workers()->run_task(&keep_cm_referents);
5690 } else {
5691 keep_cm_referents.work(0);
5692 }
5693
5694 set_par_threads(0);
5695
5696 // Closure to test whether a referent is alive.
5697 G1STWIsAliveClosure is_alive(this);
5698
5699 // Even when parallel reference processing is enabled, the processing
5700 // of JNI refs is serial and performed serially by the current thread
5701 // rather than by a worker. The following PSS will be used for processing
5702 // JNI refs.
5703
5704 // Use only a single queue for this PSS.
5705 G1ParScanThreadState pss(this, 0, NULL);
5706
5707 // We do not embed a reference processor in the copying/scanning
5708 // closures while we're actually processing the discovered
5709 // reference objects.
5710 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5711
5712 pss.set_evac_failure_closure(&evac_failure_cl);
5713
5714 assert(pss.queue_is_empty(), "pre-condition");
5715
5716 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5717
5718 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5719
5720 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5721
5722 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5723 // We also need to mark copied objects.
5724 copy_non_heap_cl = ©_mark_non_heap_cl;
5725 }
5726
5727 // Keep alive closure.
5728 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5729
5730 // Serial Complete GC closure
5731 G1STWDrainQueueClosure drain_queue(this, &pss);
5732
5733 // Setup the soft refs policy...
5734 rp->setup_policy(false);
5735
5736 ReferenceProcessorStats stats;
5737 if (!rp->processing_is_mt()) {
5738 // Serial reference processing...
5739 stats = rp->process_discovered_references(&is_alive,
5740 &keep_alive,
5741 &drain_queue,
5742 NULL,
5743 _gc_timer_stw,
5744 _gc_tracer_stw->gc_id());
5745 } else {
5746 // Parallel reference processing
5747 assert(rp->num_q() == no_of_gc_workers, "sanity");
5748 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5749
5750 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5751 stats = rp->process_discovered_references(&is_alive,
5752 &keep_alive,
5753 &drain_queue,
5754 &par_task_executor,
5755 _gc_timer_stw,
5756 _gc_tracer_stw->gc_id());
5757 }
5758
5759 _gc_tracer_stw->report_gc_reference_stats(stats);
5760
5761 // We have completed copying any necessary live referent objects.
5762 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5763
5764 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5765 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5766 }
5767
5768 // Weak Reference processing during an evacuation pause (part 2).
5769 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5770 double ref_enq_start = os::elapsedTime();
5771
5772 ReferenceProcessor* rp = _ref_processor_stw;
5773 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5774
5775 // Now enqueue any remaining on the discovered lists on to
5776 // the pending list.
5777 if (!rp->processing_is_mt()) {
5778 // Serial reference processing...
5779 rp->enqueue_discovered_references();
5780 } else {
5781 // Parallel reference enqueueing
5782
5783 assert(no_of_gc_workers == workers()->active_workers(),
5784 "Need to reset active workers");
5785 assert(rp->num_q() == no_of_gc_workers, "sanity");
5786 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5787
5788 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5789 rp->enqueue_discovered_references(&par_task_executor);
5790 }
5791
5792 rp->verify_no_references_recorded();
5793 assert(!rp->discovery_enabled(), "should have been disabled");
5794
5795 // FIXME
5796 // CM's reference processing also cleans up the string and symbol tables.
5797 // Should we do that here also? We could, but it is a serial operation
5798 // and could significantly increase the pause time.
5799
5800 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5801 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5802 }
5803
5804 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5805 _expand_heap_after_alloc_failure = true;
5806 _evacuation_failed = false;
5807
5808 // Should G1EvacuationFailureALot be in effect for this GC?
5809 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5810
5811 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5812
5813 // Disable the hot card cache.
5814 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5815 hot_card_cache->reset_hot_cache_claimed_index();
5816 hot_card_cache->set_use_cache(false);
5817
5818 uint n_workers;
5819 if (G1CollectedHeap::use_parallel_gc_threads()) {
5820 n_workers =
5821 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5822 workers()->active_workers(),
5823 Threads::number_of_non_daemon_threads());
5824 assert(UseDynamicNumberOfGCThreads ||
5825 n_workers == workers()->total_workers(),
5826 "If not dynamic should be using all the workers");
5827 workers()->set_active_workers(n_workers);
5828 set_par_threads(n_workers);
5829 } else {
5830 assert(n_par_threads() == 0,
5831 "Should be the original non-parallel value");
5832 n_workers = 1;
5833 }
5834
5835 G1ParTask g1_par_task(this, _task_queues);
5836
5837 init_for_evac_failure(NULL);
5838
5839 rem_set()->prepare_for_younger_refs_iterate(true);
5840
5841 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5842 double start_par_time_sec = os::elapsedTime();
5843 double end_par_time_sec;
5844
5845 {
5846 StrongRootsScope srs(this);
5847 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5848 if (g1_policy()->during_initial_mark_pause()) {
5849 ClassLoaderDataGraph::clear_claimed_marks();
5850 }
5851
5852 if (G1CollectedHeap::use_parallel_gc_threads()) {
5853 // The individual threads will set their evac-failure closures.
5854 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5855 // These tasks use ShareHeap::_process_strong_tasks
5856 assert(UseDynamicNumberOfGCThreads ||
5857 workers()->active_workers() == workers()->total_workers(),
5858 "If not dynamic should be using all the workers");
5859 workers()->run_task(&g1_par_task);
5860 } else {
5861 g1_par_task.set_for_termination(n_workers);
5862 g1_par_task.work(0);
5863 }
5864 end_par_time_sec = os::elapsedTime();
5865
5866 // Closing the inner scope will execute the destructor
5867 // for the StrongRootsScope object. We record the current
5868 // elapsed time before closing the scope so that time
5869 // taken for the SRS destructor is NOT included in the
5870 // reported parallel time.
5871 }
5872
5873 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5874 g1_policy()->phase_times()->record_par_time(par_time_ms);
5875
5876 double code_root_fixup_time_ms =
5877 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5878 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5879
5880 set_par_threads(0);
5881
5882 // Process any discovered reference objects - we have
5883 // to do this _before_ we retire the GC alloc regions
5884 // as we may have to copy some 'reachable' referent
5885 // objects (and their reachable sub-graphs) that were
5886 // not copied during the pause.
5887 process_discovered_references(n_workers);
5888
5889 // Weak root processing.
5890 {
5891 G1STWIsAliveClosure is_alive(this);
5892 G1KeepAliveClosure keep_alive(this);
5893 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5894 if (G1StringDedup::is_enabled()) {
5895 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5896 }
5897 }
5898
5899 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5900 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5901
5902 // Reset and re-enable the hot card cache.
5903 // Note the counts for the cards in the regions in the
5904 // collection set are reset when the collection set is freed.
5905 hot_card_cache->reset_hot_cache();
5906 hot_card_cache->set_use_cache(true);
5907
5908 // Migrate the strong code roots attached to each region in
5909 // the collection set. Ideally we would like to do this
5910 // after we have finished the scanning/evacuation of the
5911 // strong code roots for a particular heap region.
5912 migrate_strong_code_roots();
5913
5914 purge_code_root_memory();
5915
5916 if (g1_policy()->during_initial_mark_pause()) {
5917 // Reset the claim values set during marking the strong code roots
5918 reset_heap_region_claim_values();
5919 }
5920
5921 finalize_for_evac_failure();
5922
5923 if (evacuation_failed()) {
5924 remove_self_forwarding_pointers();
5925
5926 // Reset the G1EvacuationFailureALot counters and flags
5927 // Note: the values are reset only when an actual
5928 // evacuation failure occurs.
5929 NOT_PRODUCT(reset_evacuation_should_fail();)
5930 }
5931
5932 // Enqueue any remaining references remaining on the STW
5933 // reference processor's discovered lists. We need to do
5934 // this after the card table is cleaned (and verified) as
5935 // the act of enqueueing entries on to the pending list
5936 // will log these updates (and dirty their associated
5937 // cards). We need these updates logged to update any
5938 // RSets.
5939 enqueue_discovered_references(n_workers);
5940
5941 if (G1DeferredRSUpdate) {
5942 redirty_logged_cards();
5943 }
5944 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5945 }
5946
5947 void G1CollectedHeap::free_region(HeapRegion* hr,
5948 FreeRegionList* free_list,
5949 bool par,
5950 bool locked) {
5951 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5952 assert(!hr->is_empty(), "the region should not be empty");
5953 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5954 assert(free_list != NULL, "pre-condition");
5955
5956 if (G1VerifyBitmaps) {
5957 MemRegion mr(hr->bottom(), hr->end());
5958 concurrent_mark()->clearRangePrevBitmap(mr);
5959 }
5960
5961 // Clear the card counts for this region.
5962 // Note: we only need to do this if the region is not young
5963 // (since we don't refine cards in young regions).
5964 if (!hr->is_young()) {
5965 _cg1r->hot_card_cache()->reset_card_counts(hr);
5966 }
5967 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5968 free_list->add_ordered(hr);
5969 }
5970
5971 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5972 FreeRegionList* free_list,
5973 bool par) {
5974 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5975 assert(free_list != NULL, "pre-condition");
5976
5977 size_t hr_capacity = hr->capacity();
5978 // We need to read this before we make the region non-humongous,
5979 // otherwise the information will be gone.
5980 uint last_index = hr->last_hc_index();
5981 hr->set_notHumongous();
5982 free_region(hr, free_list, par);
5983
5984 uint i = hr->hrm_index() + 1;
5985 while (i < last_index) {
5986 HeapRegion* curr_hr = region_at(i);
5987 assert(curr_hr->continuesHumongous(), "invariant");
5988 curr_hr->set_notHumongous();
5989 free_region(curr_hr, free_list, par);
5990 i += 1;
5991 }
5992 }
5993
5994 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5995 const HeapRegionSetCount& humongous_regions_removed) {
5996 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5997 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5998 _old_set.bulk_remove(old_regions_removed);
5999 _humongous_set.bulk_remove(humongous_regions_removed);
6000 }
6001
6002 }
6003
6004 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6005 assert(list != NULL, "list can't be null");
6006 if (!list->is_empty()) {
6007 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6008 _hrm.insert_list_into_free_list(list);
6009 }
6010 }
6011
6012 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6013 _allocator->decrease_used(bytes);
6014 }
6015
6016 class G1ParCleanupCTTask : public AbstractGangTask {
6017 G1SATBCardTableModRefBS* _ct_bs;
6018 G1CollectedHeap* _g1h;
6019 HeapRegion* volatile _su_head;
6020 public:
6021 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6022 G1CollectedHeap* g1h) :
6023 AbstractGangTask("G1 Par Cleanup CT Task"),
6024 _ct_bs(ct_bs), _g1h(g1h) { }
6025
6026 void work(uint worker_id) {
6027 HeapRegion* r;
6028 while (r = _g1h->pop_dirty_cards_region()) {
6029 clear_cards(r);
6030 }
6031 }
6032
6033 void clear_cards(HeapRegion* r) {
6034 // Cards of the survivors should have already been dirtied.
6035 if (!r->is_survivor()) {
6036 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6037 }
6038 }
6039 };
6040
6041 #ifndef PRODUCT
6042 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6043 G1CollectedHeap* _g1h;
6044 G1SATBCardTableModRefBS* _ct_bs;
6045 public:
6046 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6047 : _g1h(g1h), _ct_bs(ct_bs) { }
6048 virtual bool doHeapRegion(HeapRegion* r) {
6049 if (r->is_survivor()) {
6050 _g1h->verify_dirty_region(r);
6051 } else {
6052 _g1h->verify_not_dirty_region(r);
6053 }
6054 return false;
6055 }
6056 };
6057
6058 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6059 // All of the region should be clean.
6060 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6061 MemRegion mr(hr->bottom(), hr->end());
6062 ct_bs->verify_not_dirty_region(mr);
6063 }
6064
6065 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6066 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6067 // dirty allocated blocks as they allocate them. The thread that
6068 // retires each region and replaces it with a new one will do a
6069 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6070 // not dirty that area (one less thing to have to do while holding
6071 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6072 // is dirty.
6073 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6074 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6075 if (hr->is_young()) {
6076 ct_bs->verify_g1_young_region(mr);
6077 } else {
6078 ct_bs->verify_dirty_region(mr);
6079 }
6080 }
6081
6082 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6083 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6084 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6085 verify_dirty_region(hr);
6086 }
6087 }
6088
6089 void G1CollectedHeap::verify_dirty_young_regions() {
6090 verify_dirty_young_list(_young_list->first_region());
6091 }
6092
6093 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6094 HeapWord* tams, HeapWord* end) {
6095 guarantee(tams <= end,
6096 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6097 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6098 if (result < end) {
6099 gclog_or_tty->cr();
6100 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6101 bitmap_name, result);
6102 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6103 bitmap_name, tams, end);
6104 return false;
6105 }
6106 return true;
6107 }
6108
6109 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6110 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6111 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6112
6113 HeapWord* bottom = hr->bottom();
6114 HeapWord* ptams = hr->prev_top_at_mark_start();
6115 HeapWord* ntams = hr->next_top_at_mark_start();
6116 HeapWord* end = hr->end();
6117
6118 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6119
6120 bool res_n = true;
6121 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6122 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6123 // if we happen to be in that state.
6124 if (mark_in_progress() || !_cmThread->in_progress()) {
6125 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6126 }
6127 if (!res_p || !res_n) {
6128 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6129 HR_FORMAT_PARAMS(hr));
6130 gclog_or_tty->print_cr("#### Caller: %s", caller);
6131 return false;
6132 }
6133 return true;
6134 }
6135
6136 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6137 if (!G1VerifyBitmaps) return;
6138
6139 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6140 }
6141
6142 class G1VerifyBitmapClosure : public HeapRegionClosure {
6143 private:
6144 const char* _caller;
6145 G1CollectedHeap* _g1h;
6146 bool _failures;
6147
6148 public:
6149 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6150 _caller(caller), _g1h(g1h), _failures(false) { }
6151
6152 bool failures() { return _failures; }
6153
6154 virtual bool doHeapRegion(HeapRegion* hr) {
6155 if (hr->continuesHumongous()) return false;
6156
6157 bool result = _g1h->verify_bitmaps(_caller, hr);
6158 if (!result) {
6159 _failures = true;
6160 }
6161 return false;
6162 }
6163 };
6164
6165 void G1CollectedHeap::check_bitmaps(const char* caller) {
6166 if (!G1VerifyBitmaps) return;
6167
6168 G1VerifyBitmapClosure cl(caller, this);
6169 heap_region_iterate(&cl);
6170 guarantee(!cl.failures(), "bitmap verification");
6171 }
6172 #endif // PRODUCT
6173
6174 void G1CollectedHeap::cleanUpCardTable() {
6175 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6176 double start = os::elapsedTime();
6177
6178 {
6179 // Iterate over the dirty cards region list.
6180 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6181
6182 if (G1CollectedHeap::use_parallel_gc_threads()) {
6183 set_par_threads();
6184 workers()->run_task(&cleanup_task);
6185 set_par_threads(0);
6186 } else {
6187 while (_dirty_cards_region_list) {
6188 HeapRegion* r = _dirty_cards_region_list;
6189 cleanup_task.clear_cards(r);
6190 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6191 if (_dirty_cards_region_list == r) {
6192 // The last region.
6193 _dirty_cards_region_list = NULL;
6194 }
6195 r->set_next_dirty_cards_region(NULL);
6196 }
6197 }
6198 #ifndef PRODUCT
6199 if (G1VerifyCTCleanup || VerifyAfterGC) {
6200 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6201 heap_region_iterate(&cleanup_verifier);
6202 }
6203 #endif
6204 }
6205
6206 double elapsed = os::elapsedTime() - start;
6207 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6208 }
6209
6210 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6211 size_t pre_used = 0;
6212 FreeRegionList local_free_list("Local List for CSet Freeing");
6213
6214 double young_time_ms = 0.0;
6215 double non_young_time_ms = 0.0;
6216
6217 // Since the collection set is a superset of the the young list,
6218 // all we need to do to clear the young list is clear its
6219 // head and length, and unlink any young regions in the code below
6220 _young_list->clear();
6221
6222 G1CollectorPolicy* policy = g1_policy();
6223
6224 double start_sec = os::elapsedTime();
6225 bool non_young = true;
6226
6227 HeapRegion* cur = cs_head;
6228 int age_bound = -1;
6229 size_t rs_lengths = 0;
6230
6231 while (cur != NULL) {
6232 assert(!is_on_master_free_list(cur), "sanity");
6233 if (non_young) {
6234 if (cur->is_young()) {
6235 double end_sec = os::elapsedTime();
6236 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6237 non_young_time_ms += elapsed_ms;
6238
6239 start_sec = os::elapsedTime();
6240 non_young = false;
6241 }
6242 } else {
6243 if (!cur->is_young()) {
6244 double end_sec = os::elapsedTime();
6245 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6246 young_time_ms += elapsed_ms;
6247
6248 start_sec = os::elapsedTime();
6249 non_young = true;
6250 }
6251 }
6252
6253 rs_lengths += cur->rem_set()->occupied_locked();
6254
6255 HeapRegion* next = cur->next_in_collection_set();
6256 assert(cur->in_collection_set(), "bad CS");
6257 cur->set_next_in_collection_set(NULL);
6258 cur->set_in_collection_set(false);
6259
6260 if (cur->is_young()) {
6261 int index = cur->young_index_in_cset();
6262 assert(index != -1, "invariant");
6263 assert((uint) index < policy->young_cset_region_length(), "invariant");
6264 size_t words_survived = _surviving_young_words[index];
6265 cur->record_surv_words_in_group(words_survived);
6266
6267 // At this point the we have 'popped' cur from the collection set
6268 // (linked via next_in_collection_set()) but it is still in the
6269 // young list (linked via next_young_region()). Clear the
6270 // _next_young_region field.
6271 cur->set_next_young_region(NULL);
6272 } else {
6273 int index = cur->young_index_in_cset();
6274 assert(index == -1, "invariant");
6275 }
6276
6277 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6278 (!cur->is_young() && cur->young_index_in_cset() == -1),
6279 "invariant" );
6280
6281 if (!cur->evacuation_failed()) {
6282 MemRegion used_mr = cur->used_region();
6283
6284 // And the region is empty.
6285 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6286 pre_used += cur->used();
6287 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6288 } else {
6289 cur->uninstall_surv_rate_group();
6290 if (cur->is_young()) {
6291 cur->set_young_index_in_cset(-1);
6292 }
6293 cur->set_not_young();
6294 cur->set_evacuation_failed(false);
6295 // The region is now considered to be old.
6296 _old_set.add(cur);
6297 evacuation_info.increment_collectionset_used_after(cur->used());
6298 }
6299 cur = next;
6300 }
6301
6302 evacuation_info.set_regions_freed(local_free_list.length());
6303 policy->record_max_rs_lengths(rs_lengths);
6304 policy->cset_regions_freed();
6305
6306 double end_sec = os::elapsedTime();
6307 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6308
6309 if (non_young) {
6310 non_young_time_ms += elapsed_ms;
6311 } else {
6312 young_time_ms += elapsed_ms;
6313 }
6314
6315 prepend_to_freelist(&local_free_list);
6316 decrement_summary_bytes(pre_used);
6317 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6318 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6319 }
6320
6321 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6322 private:
6323 FreeRegionList* _free_region_list;
6324 HeapRegionSet* _proxy_set;
6325 HeapRegionSetCount _humongous_regions_removed;
6326 size_t _freed_bytes;
6327 public:
6328
6329 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6330 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6331 }
6332
6333 virtual bool doHeapRegion(HeapRegion* r) {
6334 if (!r->startsHumongous()) {
6335 return false;
6336 }
6337
6338 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6339
6340 oop obj = (oop)r->bottom();
6341 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6342
6343 // The following checks whether the humongous object is live are sufficient.
6344 // The main additional check (in addition to having a reference from the roots
6345 // or the young gen) is whether the humongous object has a remembered set entry.
6346 //
6347 // A humongous object cannot be live if there is no remembered set for it
6348 // because:
6349 // - there can be no references from within humongous starts regions referencing
6350 // the object because we never allocate other objects into them.
6351 // (I.e. there are no intra-region references that may be missed by the
6352 // remembered set)
6353 // - as soon there is a remembered set entry to the humongous starts region
6354 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6355 // until the end of a concurrent mark.
6356 //
6357 // It is not required to check whether the object has been found dead by marking
6358 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6359 // all objects allocated during that time are considered live.
6360 // SATB marking is even more conservative than the remembered set.
6361 // So if at this point in the collection there is no remembered set entry,
6362 // nobody has a reference to it.
6363 // At the start of collection we flush all refinement logs, and remembered sets
6364 // are completely up-to-date wrt to references to the humongous object.
6365 //
6366 // Other implementation considerations:
6367 // - never consider object arrays: while they are a valid target, they have not
6368 // been observed to be used as temporary objects.
6369 // - they would also pose considerable effort for cleaning up the the remembered
6370 // sets.
6371 // While this cleanup is not strictly necessary to be done (or done instantly),
6372 // given that their occurrence is very low, this saves us this additional
6373 // complexity.
6374 uint region_idx = r->hrm_index();
6375 if (g1h->humongous_is_live(region_idx) ||
6376 g1h->humongous_region_is_always_live(region_idx)) {
6377
6378 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6379 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",
6380 r->isHumongous(),
6381 region_idx,
6382 r->rem_set()->occupied(),
6383 r->rem_set()->strong_code_roots_list_length(),
6384 next_bitmap->isMarked(r->bottom()),
6385 g1h->humongous_is_live(region_idx),
6386 obj->is_objArray()
6387 );
6388 }
6389
6390 return false;
6391 }
6392
6393 guarantee(!obj->is_objArray(),
6394 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6395 r->bottom()));
6396
6397 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6398 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",
6399 r->isHumongous(),
6400 r->bottom(),
6401 region_idx,
6402 r->region_num(),
6403 r->rem_set()->occupied(),
6404 r->rem_set()->strong_code_roots_list_length(),
6405 next_bitmap->isMarked(r->bottom()),
6406 g1h->humongous_is_live(region_idx),
6407 obj->is_objArray()
6408 );
6409 }
6410 // Need to clear mark bit of the humongous object if already set.
6411 if (next_bitmap->isMarked(r->bottom())) {
6412 next_bitmap->clear(r->bottom());
6413 }
6414 _freed_bytes += r->used();
6415 r->set_containing_set(NULL);
6416 _humongous_regions_removed.increment(1u, r->capacity());
6417 g1h->free_humongous_region(r, _free_region_list, false);
6418
6419 return false;
6420 }
6421
6422 HeapRegionSetCount& humongous_free_count() {
6423 return _humongous_regions_removed;
6424 }
6425
6426 size_t bytes_freed() const {
6427 return _freed_bytes;
6428 }
6429
6430 size_t humongous_reclaimed() const {
6431 return _humongous_regions_removed.length();
6432 }
6433 };
6434
6435 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6436 assert_at_safepoint(true);
6437
6438 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) {
6439 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6440 return;
6441 }
6442
6443 double start_time = os::elapsedTime();
6444
6445 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6446
6447 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6448 heap_region_iterate(&cl);
6449
6450 HeapRegionSetCount empty_set;
6451 remove_from_old_sets(empty_set, cl.humongous_free_count());
6452
6453 G1HRPrinter* hr_printer = _g1h->hr_printer();
6454 if (hr_printer->is_active()) {
6455 FreeRegionListIterator iter(&local_cleanup_list);
6456 while (iter.more_available()) {
6457 HeapRegion* hr = iter.get_next();
6458 hr_printer->cleanup(hr);
6459 }
6460 }
6461
6462 prepend_to_freelist(&local_cleanup_list);
6463 decrement_summary_bytes(cl.bytes_freed());
6464
6465 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6466 cl.humongous_reclaimed());
6467 }
6468
6469 // This routine is similar to the above but does not record
6470 // any policy statistics or update free lists; we are abandoning
6471 // the current incremental collection set in preparation of a
6472 // full collection. After the full GC we will start to build up
6473 // the incremental collection set again.
6474 // This is only called when we're doing a full collection
6475 // and is immediately followed by the tearing down of the young list.
6476
6477 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6478 HeapRegion* cur = cs_head;
6479
6480 while (cur != NULL) {
6481 HeapRegion* next = cur->next_in_collection_set();
6482 assert(cur->in_collection_set(), "bad CS");
6483 cur->set_next_in_collection_set(NULL);
6484 cur->set_in_collection_set(false);
6485 cur->set_young_index_in_cset(-1);
6486 cur = next;
6487 }
6488 }
6489
6490 void G1CollectedHeap::set_free_regions_coming() {
6491 if (G1ConcRegionFreeingVerbose) {
6492 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6493 "setting free regions coming");
6494 }
6495
6496 assert(!free_regions_coming(), "pre-condition");
6497 _free_regions_coming = true;
6498 }
6499
6500 void G1CollectedHeap::reset_free_regions_coming() {
6501 assert(free_regions_coming(), "pre-condition");
6502
6503 {
6504 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6505 _free_regions_coming = false;
6506 SecondaryFreeList_lock->notify_all();
6507 }
6508
6509 if (G1ConcRegionFreeingVerbose) {
6510 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6511 "reset free regions coming");
6512 }
6513 }
6514
6515 void G1CollectedHeap::wait_while_free_regions_coming() {
6516 // Most of the time we won't have to wait, so let's do a quick test
6517 // first before we take the lock.
6518 if (!free_regions_coming()) {
6519 return;
6520 }
6521
6522 if (G1ConcRegionFreeingVerbose) {
6523 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6524 "waiting for free regions");
6525 }
6526
6527 {
6528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6529 while (free_regions_coming()) {
6530 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6531 }
6532 }
6533
6534 if (G1ConcRegionFreeingVerbose) {
6535 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6536 "done waiting for free regions");
6537 }
6538 }
6539
6540 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6541 assert(heap_lock_held_for_gc(),
6542 "the heap lock should already be held by or for this thread");
6543 _young_list->push_region(hr);
6544 }
6545
6546 class NoYoungRegionsClosure: public HeapRegionClosure {
6547 private:
6548 bool _success;
6549 public:
6550 NoYoungRegionsClosure() : _success(true) { }
6551 bool doHeapRegion(HeapRegion* r) {
6552 if (r->is_young()) {
6553 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6554 r->bottom(), r->end());
6555 _success = false;
6556 }
6557 return false;
6558 }
6559 bool success() { return _success; }
6560 };
6561
6562 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6563 bool ret = _young_list->check_list_empty(check_sample);
6564
6565 if (check_heap) {
6566 NoYoungRegionsClosure closure;
6567 heap_region_iterate(&closure);
6568 ret = ret && closure.success();
6569 }
6570
6571 return ret;
6572 }
6573
6574 class TearDownRegionSetsClosure : public HeapRegionClosure {
6575 private:
6576 HeapRegionSet *_old_set;
6577
6578 public:
6579 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6580
6581 bool doHeapRegion(HeapRegion* r) {
6582 if (r->is_empty()) {
6583 // We ignore empty regions, we'll empty the free list afterwards
6584 } else if (r->is_young()) {
6585 // We ignore young regions, we'll empty the young list afterwards
6586 } else if (r->isHumongous()) {
6587 // We ignore humongous regions, we're not tearing down the
6588 // humongous region set
6589 } else {
6590 // The rest should be old
6591 _old_set->remove(r);
6592 }
6593 return false;
6594 }
6595
6596 ~TearDownRegionSetsClosure() {
6597 assert(_old_set->is_empty(), "post-condition");
6598 }
6599 };
6600
6601 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6602 assert_at_safepoint(true /* should_be_vm_thread */);
6603
6604 if (!free_list_only) {
6605 TearDownRegionSetsClosure cl(&_old_set);
6606 heap_region_iterate(&cl);
6607
6608 // Note that emptying the _young_list is postponed and instead done as
6609 // the first step when rebuilding the regions sets again. The reason for
6610 // this is that during a full GC string deduplication needs to know if
6611 // a collected region was young or old when the full GC was initiated.
6612 }
6613 _hrm.remove_all_free_regions();
6614 }
6615
6616 class RebuildRegionSetsClosure : public HeapRegionClosure {
6617 private:
6618 bool _free_list_only;
6619 HeapRegionSet* _old_set;
6620 HeapRegionManager* _hrm;
6621 size_t _total_used;
6622
6623 public:
6624 RebuildRegionSetsClosure(bool free_list_only,
6625 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6626 _free_list_only(free_list_only),
6627 _old_set(old_set), _hrm(hrm), _total_used(0) {
6628 assert(_hrm->num_free_regions() == 0, "pre-condition");
6629 if (!free_list_only) {
6630 assert(_old_set->is_empty(), "pre-condition");
6631 }
6632 }
6633
6634 bool doHeapRegion(HeapRegion* r) {
6635 if (r->continuesHumongous()) {
6636 return false;
6637 }
6638
6639 if (r->is_empty()) {
6640 // Add free regions to the free list
6641 r->set_allocation_context(AllocationContext::system());
6642 _hrm->insert_into_free_list(r);
6643 } else if (!_free_list_only) {
6644 assert(!r->is_young(), "we should not come across young regions");
6645
6646 if (r->isHumongous()) {
6647 // We ignore humongous regions, we left the humongous set unchanged
6648 } else {
6649 // The rest should be old, add them to the old set
6650 _old_set->add(r);
6651 }
6652 _total_used += r->used();
6653 }
6654
6655 return false;
6656 }
6657
6658 size_t total_used() {
6659 return _total_used;
6660 }
6661 };
6662
6663 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6664 assert_at_safepoint(true /* should_be_vm_thread */);
6665
6666 if (!free_list_only) {
6667 _young_list->empty_list();
6668 }
6669
6670 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6671 heap_region_iterate(&cl);
6672
6673 if (!free_list_only) {
6674 _allocator->set_used(cl.total_used());
6675 }
6676 assert(_allocator->used_unlocked() == recalculate_used(),
6677 err_msg("inconsistent _allocator->used_unlocked(), "
6678 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6679 _allocator->used_unlocked(), recalculate_used()));
6680 }
6681
6682 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6683 _refine_cte_cl->set_concurrent(concurrent);
6684 }
6685
6686 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6687 HeapRegion* hr = heap_region_containing(p);
6688 return hr->is_in(p);
6689 }
6690
6691 // Methods for the mutator alloc region
6692
6693 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6694 bool force) {
6695 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6696 assert(!force || g1_policy()->can_expand_young_list(),
6697 "if force is true we should be able to expand the young list");
6698 bool young_list_full = g1_policy()->is_young_list_full();
6699 if (force || !young_list_full) {
6700 HeapRegion* new_alloc_region = new_region(word_size,
6701 false /* is_old */,
6702 false /* do_expand */);
6703 if (new_alloc_region != NULL) {
6704 set_region_short_lived_locked(new_alloc_region);
6705 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6706 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6707 return new_alloc_region;
6708 }
6709 }
6710 return NULL;
6711 }
6712
6713 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6714 size_t allocated_bytes) {
6715 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6716 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6717
6718 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6719 _allocator->increase_used(allocated_bytes);
6720 _hr_printer.retire(alloc_region);
6721 // We update the eden sizes here, when the region is retired,
6722 // instead of when it's allocated, since this is the point that its
6723 // used space has been recored in _summary_bytes_used.
6724 g1mm()->update_eden_size();
6725 }
6726
6727 void G1CollectedHeap::set_par_threads() {
6728 // Don't change the number of workers. Use the value previously set
6729 // in the workgroup.
6730 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6731 uint n_workers = workers()->active_workers();
6732 assert(UseDynamicNumberOfGCThreads ||
6733 n_workers == workers()->total_workers(),
6734 "Otherwise should be using the total number of workers");
6735 if (n_workers == 0) {
6736 assert(false, "Should have been set in prior evacuation pause.");
6737 n_workers = ParallelGCThreads;
6738 workers()->set_active_workers(n_workers);
6739 }
6740 set_par_threads(n_workers);
6741 }
6742
6743 // Methods for the GC alloc regions
6744
6745 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6746 uint count,
6747 GCAllocPurpose ap) {
6748 assert(FreeList_lock->owned_by_self(), "pre-condition");
6749
6750 if (count < g1_policy()->max_regions(ap)) {
6751 bool survivor = (ap == GCAllocForSurvived);
6752 HeapRegion* new_alloc_region = new_region(word_size,
6753 !survivor,
6754 true /* do_expand */);
6755 if (new_alloc_region != NULL) {
6756 // We really only need to do this for old regions given that we
6757 // should never scan survivors. But it doesn't hurt to do it
6758 // for survivors too.
6759 new_alloc_region->record_top_and_timestamp();
6760 if (survivor) {
6761 new_alloc_region->set_survivor();
6762 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6763 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6764 } else {
6765 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6766 check_bitmaps("Old Region Allocation", new_alloc_region);
6767 }
6768 bool during_im = g1_policy()->during_initial_mark_pause();
6769 new_alloc_region->note_start_of_copying(during_im);
6770 return new_alloc_region;
6771 } else {
6772 g1_policy()->note_alloc_region_limit_reached(ap);
6773 }
6774 }
6775 return NULL;
6776 }
6777
6778 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6779 size_t allocated_bytes,
6780 GCAllocPurpose ap) {
6781 bool during_im = g1_policy()->during_initial_mark_pause();
6782 alloc_region->note_end_of_copying(during_im);
6783 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6784 if (ap == GCAllocForSurvived) {
6785 young_list()->add_survivor_region(alloc_region);
6786 } else {
6787 _old_set.add(alloc_region);
6788 }
6789 _hr_printer.retire(alloc_region);
6790 }
6791
6792 // Heap region set verification
6793
6794 class VerifyRegionListsClosure : public HeapRegionClosure {
6795 private:
6796 HeapRegionSet* _old_set;
6797 HeapRegionSet* _humongous_set;
6798 HeapRegionManager* _hrm;
6799
6800 public:
6801 HeapRegionSetCount _old_count;
6802 HeapRegionSetCount _humongous_count;
6803 HeapRegionSetCount _free_count;
6804
6805 VerifyRegionListsClosure(HeapRegionSet* old_set,
6806 HeapRegionSet* humongous_set,
6807 HeapRegionManager* hrm) :
6808 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6809 _old_count(), _humongous_count(), _free_count(){ }
6810
6811 bool doHeapRegion(HeapRegion* hr) {
6812 if (hr->continuesHumongous()) {
6813 return false;
6814 }
6815
6816 if (hr->is_young()) {
6817 // TODO
6818 } else if (hr->startsHumongous()) {
6819 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6820 _humongous_count.increment(1u, hr->capacity());
6821 } else if (hr->is_empty()) {
6822 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6823 _free_count.increment(1u, hr->capacity());
6824 } else {
6825 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6826 _old_count.increment(1u, hr->capacity());
6827 }
6828 return false;
6829 }
6830
6831 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6832 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6833 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6834 old_set->total_capacity_bytes(), _old_count.capacity()));
6835
6836 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6837 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6838 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6839
6840 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()));
6841 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6842 free_list->total_capacity_bytes(), _free_count.capacity()));
6843 }
6844 };
6845
6846 void G1CollectedHeap::verify_region_sets() {
6847 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6848
6849 // First, check the explicit lists.
6850 _hrm.verify();
6851 {
6852 // Given that a concurrent operation might be adding regions to
6853 // the secondary free list we have to take the lock before
6854 // verifying it.
6855 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6856 _secondary_free_list.verify_list();
6857 }
6858
6859 // If a concurrent region freeing operation is in progress it will
6860 // be difficult to correctly attributed any free regions we come
6861 // across to the correct free list given that they might belong to
6862 // one of several (free_list, secondary_free_list, any local lists,
6863 // etc.). So, if that's the case we will skip the rest of the
6864 // verification operation. Alternatively, waiting for the concurrent
6865 // operation to complete will have a non-trivial effect on the GC's
6866 // operation (no concurrent operation will last longer than the
6867 // interval between two calls to verification) and it might hide
6868 // any issues that we would like to catch during testing.
6869 if (free_regions_coming()) {
6870 return;
6871 }
6872
6873 // Make sure we append the secondary_free_list on the free_list so
6874 // that all free regions we will come across can be safely
6875 // attributed to the free_list.
6876 append_secondary_free_list_if_not_empty_with_lock();
6877
6878 // Finally, make sure that the region accounting in the lists is
6879 // consistent with what we see in the heap.
6880
6881 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6882 heap_region_iterate(&cl);
6883 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6884 }
6885
6886 // Optimized nmethod scanning
6887
6888 class RegisterNMethodOopClosure: public OopClosure {
6889 G1CollectedHeap* _g1h;
6890 nmethod* _nm;
6891
6892 template <class T> void do_oop_work(T* p) {
6893 T heap_oop = oopDesc::load_heap_oop(p);
6894 if (!oopDesc::is_null(heap_oop)) {
6895 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6896 HeapRegion* hr = _g1h->heap_region_containing(obj);
6897 assert(!hr->continuesHumongous(),
6898 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6899 " starting at "HR_FORMAT,
6900 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6901
6902 // HeapRegion::add_strong_code_root() avoids adding duplicate
6903 // entries but having duplicates is OK since we "mark" nmethods
6904 // as visited when we scan the strong code root lists during the GC.
6905 hr->add_strong_code_root(_nm);
6906 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6907 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6908 _nm, HR_FORMAT_PARAMS(hr)));
6909 }
6910 }
6911
6912 public:
6913 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6914 _g1h(g1h), _nm(nm) {}
6915
6916 void do_oop(oop* p) { do_oop_work(p); }
6917 void do_oop(narrowOop* p) { do_oop_work(p); }
6918 };
6919
6920 class UnregisterNMethodOopClosure: public OopClosure {
6921 G1CollectedHeap* _g1h;
6922 nmethod* _nm;
6923
6924 template <class T> void do_oop_work(T* p) {
6925 T heap_oop = oopDesc::load_heap_oop(p);
6926 if (!oopDesc::is_null(heap_oop)) {
6927 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6928 HeapRegion* hr = _g1h->heap_region_containing(obj);
6929 assert(!hr->continuesHumongous(),
6930 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6931 " starting at "HR_FORMAT,
6932 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6933
6934 hr->remove_strong_code_root(_nm);
6935 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6936 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6937 _nm, HR_FORMAT_PARAMS(hr)));
6938 }
6939 }
6940
6941 public:
6942 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6943 _g1h(g1h), _nm(nm) {}
6944
6945 void do_oop(oop* p) { do_oop_work(p); }
6946 void do_oop(narrowOop* p) { do_oop_work(p); }
6947 };
6948
6949 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6950 CollectedHeap::register_nmethod(nm);
6951
6952 guarantee(nm != NULL, "sanity");
6953 RegisterNMethodOopClosure reg_cl(this, nm);
6954 nm->oops_do(®_cl);
6955 }
6956
6957 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6958 CollectedHeap::unregister_nmethod(nm);
6959
6960 guarantee(nm != NULL, "sanity");
6961 UnregisterNMethodOopClosure reg_cl(this, nm);
6962 nm->oops_do(®_cl, true);
6963 }
6964
6965 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6966 public:
6967 bool doHeapRegion(HeapRegion *hr) {
6968 assert(!hr->isHumongous(),
6969 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6970 HR_FORMAT_PARAMS(hr)));
6971 hr->migrate_strong_code_roots();
6972 return false;
6973 }
6974 };
6975
6976 void G1CollectedHeap::migrate_strong_code_roots() {
6977 MigrateCodeRootsHeapRegionClosure cl;
6978 double migrate_start = os::elapsedTime();
6979 collection_set_iterate(&cl);
6980 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6981 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6982 }
6983
6984 void G1CollectedHeap::purge_code_root_memory() {
6985 double purge_start = os::elapsedTime();
6986 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6987 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6988 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6989 }
6990
6991 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6992 G1CollectedHeap* _g1h;
6993
6994 public:
6995 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6996 _g1h(g1h) {}
6997
6998 void do_code_blob(CodeBlob* cb) {
6999 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7000 if (nm == NULL) {
7001 return;
7002 }
7003
7004 if (ScavengeRootsInCode) {
7005 _g1h->register_nmethod(nm);
7006 }
7007 }
7008 };
7009
7010 void G1CollectedHeap::rebuild_strong_code_roots() {
7011 RebuildStrongCodeRootClosure blob_cl(this);
7012 CodeCache::blobs_do(&blob_cl);
7013 }