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 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1StringDedup.hpp"
43 #include "gc_implementation/g1/g1YCTypes.hpp"
44 #include "gc_implementation/g1/heapRegion.inline.hpp"
45 #include "gc_implementation/g1/heapRegionRemSet.hpp"
46 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
47 #include "gc_implementation/g1/vm_operations_g1.hpp"
48 #include "gc_implementation/shared/gcHeapSummary.hpp"
49 #include "gc_implementation/shared/gcTimer.hpp"
50 #include "gc_implementation/shared/gcTrace.hpp"
51 #include "gc_implementation/shared/gcTraceTime.hpp"
52 #include "gc_implementation/shared/isGCActiveMark.hpp"
53 #include "memory/gcLocker.inline.hpp"
54 #include "memory/generationSpec.hpp"
55 #include "memory/iterator.hpp"
56 #include "memory/referenceProcessor.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "oops/oop.pcgc.inline.hpp"
59 #include "runtime/vmThread.hpp"
60 #include "utilities/ticks.hpp"
61
62 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
63
64 // turn it on so that the contents of the young list (scan-only /
65 // to-be-collected) are printed at "strategic" points before / during
66 // / after the collection --- this is useful for debugging
67 #define YOUNG_LIST_VERBOSE 0
68 // CURRENT STATUS
69 // This file is under construction. Search for "FIXME".
70
71 // INVARIANTS/NOTES
72 //
73 // All allocation activity covered by the G1CollectedHeap interface is
74 // serialized by acquiring the HeapLock. This happens in mem_allocate
75 // and allocate_new_tlab, which are the "entry" points to the
76 // allocation code from the rest of the JVM. (Note that this does not
77 // apply to TLAB allocation, which is not part of this interface: it
78 // is done by clients of this interface.)
79
80 // Notes on implementation of parallelism in different tasks.
81 //
82 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
83 // The number of GC workers is passed to heap_region_par_iterate_chunked().
84 // It does use run_task() which sets _n_workers in the task.
85 // G1ParTask executes g1_process_strong_roots() ->
86 // SharedHeap::process_strong_roots() which calls eventually to
87 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
88 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
89 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
90 //
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 SuspendibleThreadSet* _sts;
96 G1RemSet* _g1rs;
97 ConcurrentG1Refine* _cg1r;
98 bool _concurrent;
99 public:
100 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
101 G1RemSet* g1rs,
102 ConcurrentG1Refine* cg1r) :
103 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
104 {}
105 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
106 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
107 // This path is executed by the concurrent refine or mutator threads,
108 // concurrently, and so we do not care if card_ptr contains references
109 // that point into the collection set.
110 assert(!oops_into_cset, "should be");
111
112 if (_concurrent && _sts->should_yield()) {
113 // Caller will actually yield.
114 return false;
115 }
116 // Otherwise, we finished successfully; return true.
117 return true;
118 }
119 void set_concurrent(bool b) { _concurrent = b; }
120 };
121
122
123 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
124 int _calls;
125 G1CollectedHeap* _g1h;
126 CardTableModRefBS* _ctbs;
127 int _histo[256];
128 public:
129 ClearLoggedCardTableEntryClosure() :
130 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
131 {
132 for (int i = 0; i < 256; i++) _histo[i] = 0;
133 }
134 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
135 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
136 _calls++;
137 unsigned char* ujb = (unsigned char*)card_ptr;
138 int ind = (int)(*ujb);
139 _histo[ind]++;
140 *card_ptr = -1;
141 }
142 return true;
143 }
144 int calls() { return _calls; }
145 void print_histo() {
146 gclog_or_tty->print_cr("Card table value histogram:");
147 for (int i = 0; i < 256; i++) {
148 if (_histo[i] != 0) {
149 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
150 }
151 }
152 }
153 };
154
155 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
156 int _calls;
157 G1CollectedHeap* _g1h;
158 CardTableModRefBS* _ctbs;
159 public:
160 RedirtyLoggedCardTableEntryClosure() :
161 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
162
163 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
164 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
165 _calls++;
166 *card_ptr = 0;
167 }
168 return true;
169 }
170 int calls() { return _calls; }
171 };
172
173 YoungList::YoungList(G1CollectedHeap* g1h) :
174 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
175 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
176 guarantee(check_list_empty(false), "just making sure...");
177 }
178
179 void YoungList::push_region(HeapRegion *hr) {
180 assert(!hr->is_young(), "should not already be young");
181 assert(hr->get_next_young_region() == NULL, "cause it should!");
182
183 hr->set_next_young_region(_head);
184 _head = hr;
185
186 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
187 ++_length;
188 }
189
190 void YoungList::add_survivor_region(HeapRegion* hr) {
191 assert(hr->is_survivor(), "should be flagged as survivor region");
192 assert(hr->get_next_young_region() == NULL, "cause it should!");
193
194 hr->set_next_young_region(_survivor_head);
195 if (_survivor_head == NULL) {
196 _survivor_tail = hr;
197 }
198 _survivor_head = hr;
199 ++_survivor_length;
200 }
201
202 void YoungList::empty_list(HeapRegion* list) {
203 while (list != NULL) {
204 HeapRegion* next = list->get_next_young_region();
205 list->set_next_young_region(NULL);
206 list->uninstall_surv_rate_group();
207 list->set_not_young();
208 list = next;
209 }
210 }
211
212 void YoungList::empty_list() {
213 assert(check_list_well_formed(), "young list should be well formed");
214
215 empty_list(_head);
216 _head = NULL;
217 _length = 0;
218
219 empty_list(_survivor_head);
220 _survivor_head = NULL;
221 _survivor_tail = NULL;
222 _survivor_length = 0;
223
224 _last_sampled_rs_lengths = 0;
225
226 assert(check_list_empty(false), "just making sure...");
227 }
228
229 bool YoungList::check_list_well_formed() {
230 bool ret = true;
231
232 uint length = 0;
233 HeapRegion* curr = _head;
234 HeapRegion* last = NULL;
235 while (curr != NULL) {
236 if (!curr->is_young()) {
237 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
238 "incorrectly tagged (y: %d, surv: %d)",
239 curr->bottom(), curr->end(),
240 curr->is_young(), curr->is_survivor());
241 ret = false;
242 }
243 ++length;
244 last = curr;
245 curr = curr->get_next_young_region();
246 }
247 ret = ret && (length == _length);
248
249 if (!ret) {
250 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
251 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
252 length, _length);
253 }
254
255 return ret;
256 }
257
258 bool YoungList::check_list_empty(bool check_sample) {
259 bool ret = true;
260
261 if (_length != 0) {
262 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
263 _length);
264 ret = false;
265 }
266 if (check_sample && _last_sampled_rs_lengths != 0) {
267 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
268 ret = false;
269 }
270 if (_head != NULL) {
271 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
272 ret = false;
273 }
274 if (!ret) {
275 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
276 }
277
278 return ret;
279 }
280
281 void
282 YoungList::rs_length_sampling_init() {
283 _sampled_rs_lengths = 0;
284 _curr = _head;
285 }
286
287 bool
288 YoungList::rs_length_sampling_more() {
289 return _curr != NULL;
290 }
291
292 void
293 YoungList::rs_length_sampling_next() {
294 assert( _curr != NULL, "invariant" );
295 size_t rs_length = _curr->rem_set()->occupied();
296
297 _sampled_rs_lengths += rs_length;
298
299 // The current region may not yet have been added to the
300 // incremental collection set (it gets added when it is
301 // retired as the current allocation region).
302 if (_curr->in_collection_set()) {
303 // Update the collection set policy information for this region
304 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
305 }
306
307 _curr = _curr->get_next_young_region();
308 if (_curr == NULL) {
309 _last_sampled_rs_lengths = _sampled_rs_lengths;
310 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
311 }
312 }
313
314 void
315 YoungList::reset_auxilary_lists() {
316 guarantee( is_empty(), "young list should be empty" );
317 assert(check_list_well_formed(), "young list should be well formed");
318
319 // Add survivor regions to SurvRateGroup.
320 _g1h->g1_policy()->note_start_adding_survivor_regions();
321 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
322
323 int young_index_in_cset = 0;
324 for (HeapRegion* curr = _survivor_head;
325 curr != NULL;
326 curr = curr->get_next_young_region()) {
327 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
328
329 // The region is a non-empty survivor so let's add it to
330 // the incremental collection set for the next evacuation
331 // pause.
332 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
333 young_index_in_cset += 1;
334 }
335 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
336 _g1h->g1_policy()->note_stop_adding_survivor_regions();
337
338 _head = _survivor_head;
339 _length = _survivor_length;
340 if (_survivor_head != NULL) {
341 assert(_survivor_tail != NULL, "cause it shouldn't be");
342 assert(_survivor_length > 0, "invariant");
343 _survivor_tail->set_next_young_region(NULL);
344 }
345
346 // Don't clear the survivor list handles until the start of
347 // the next evacuation pause - we need it in order to re-tag
348 // the survivor regions from this evacuation pause as 'young'
349 // at the start of the next.
350
351 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
352
353 assert(check_list_well_formed(), "young list should be well formed");
354 }
355
356 void YoungList::print() {
357 HeapRegion* lists[] = {_head, _survivor_head};
358 const char* names[] = {"YOUNG", "SURVIVOR"};
359
360 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
361 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
362 HeapRegion *curr = lists[list];
363 if (curr == NULL)
364 gclog_or_tty->print_cr(" empty");
365 while (curr != NULL) {
366 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
367 HR_FORMAT_PARAMS(curr),
368 curr->prev_top_at_mark_start(),
369 curr->next_top_at_mark_start(),
370 curr->age_in_surv_rate_group_cond());
371 curr = curr->get_next_young_region();
372 }
373 }
374
375 gclog_or_tty->print_cr("");
376 }
377
378 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
379 {
380 // Claim the right to put the region on the dirty cards region list
381 // by installing a self pointer.
382 HeapRegion* next = hr->get_next_dirty_cards_region();
383 if (next == NULL) {
384 HeapRegion* res = (HeapRegion*)
385 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
386 NULL);
387 if (res == NULL) {
388 HeapRegion* head;
389 do {
390 // Put the region to the dirty cards region list.
391 head = _dirty_cards_region_list;
392 next = (HeapRegion*)
393 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
394 if (next == head) {
395 assert(hr->get_next_dirty_cards_region() == hr,
396 "hr->get_next_dirty_cards_region() != hr");
397 if (next == NULL) {
398 // The last region in the list points to itself.
399 hr->set_next_dirty_cards_region(hr);
400 } else {
401 hr->set_next_dirty_cards_region(next);
402 }
403 }
404 } while (next != head);
405 }
406 }
407 }
408
409 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
410 {
411 HeapRegion* head;
412 HeapRegion* hr;
413 do {
414 head = _dirty_cards_region_list;
415 if (head == NULL) {
416 return NULL;
417 }
418 HeapRegion* new_head = head->get_next_dirty_cards_region();
419 if (head == new_head) {
420 // The last region.
421 new_head = NULL;
422 }
423 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
424 head);
425 } while (hr != head);
426 assert(hr != NULL, "invariant");
427 hr->set_next_dirty_cards_region(NULL);
428 return hr;
429 }
430
431 void G1CollectedHeap::stop_conc_gc_threads() {
432 _cg1r->stop();
433 _cmThread->stop();
434 }
435
436 #ifdef ASSERT
437 // A region is added to the collection set as it is retired
438 // so an address p can point to a region which will be in the
439 // collection set but has not yet been retired. This method
440 // therefore is only accurate during a GC pause after all
441 // regions have been retired. It is used for debugging
442 // to check if an nmethod has references to objects that can
443 // be move during a partial collection. Though it can be
444 // inaccurate, it is sufficient for G1 because the conservative
445 // implementation of is_scavengable() for G1 will indicate that
446 // all nmethods must be scanned during a partial collection.
447 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
448 HeapRegion* hr = heap_region_containing(p);
449 return hr != NULL && hr->in_collection_set();
450 }
451 #endif
452
453 // Returns true if the reference points to an object that
454 // can move in an incremental collection.
455 bool G1CollectedHeap::is_scavengable(const void* p) {
456 G1CollectedHeap* g1h = G1CollectedHeap::heap();
457 G1CollectorPolicy* g1p = g1h->g1_policy();
458 HeapRegion* hr = heap_region_containing(p);
459 if (hr == NULL) {
460 // null
461 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
462 return false;
463 } else {
464 return !hr->isHumongous();
465 }
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.set_closure(&clear);
480 dcqs.apply_closure_to_all_completed_buffers();
481 dcqs.iterate_closure_all_threads(false);
482 clear.print_histo();
483
484 // Now ensure that there's no dirty cards.
485 CountNonCleanMemRegionClosure count2(this);
486 ct_bs->mod_card_iterate(&count2);
487 if (count2.n() != 0) {
488 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
489 count2.n(), orig_count);
490 }
491 guarantee(count2.n() == 0, "Card table should be clean.");
492
493 RedirtyLoggedCardTableEntryClosure redirty;
494 JavaThread::dirty_card_queue_set().set_closure(&redirty);
495 dcqs.apply_closure_to_all_completed_buffers();
496 dcqs.iterate_closure_all_threads(false);
497 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
498 clear.calls(), orig_count);
499 guarantee(redirty.calls() == clear.calls(),
500 "Or else mechanism is broken.");
501
502 CountNonCleanMemRegionClosure count3(this);
503 ct_bs->mod_card_iterate(&count3);
504 if (count3.n() != orig_count) {
505 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
506 orig_count, count3.n());
507 guarantee(count3.n() >= orig_count, "Should have restored them all.");
508 }
509
510 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
511 }
512
513 // Private class members.
514
515 G1CollectedHeap* G1CollectedHeap::_g1h;
516
517 // Private methods.
518
519 HeapRegion*
520 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
521 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
522 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
523 if (!_secondary_free_list.is_empty()) {
524 if (G1ConcRegionFreeingVerbose) {
525 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
526 "secondary_free_list has %u entries",
527 _secondary_free_list.length());
528 }
529 // It looks as if there are free regions available on the
530 // secondary_free_list. Let's move them to the free_list and try
531 // again to allocate from it.
532 append_secondary_free_list();
533
534 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
535 "empty we should have moved at least one entry to the free_list");
536 HeapRegion* res = _free_list.remove_region(is_old);
537 if (G1ConcRegionFreeingVerbose) {
538 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
539 "allocated "HR_FORMAT" from secondary_free_list",
540 HR_FORMAT_PARAMS(res));
541 }
542 return res;
543 }
544
545 // Wait here until we get notified either when (a) there are no
546 // more free regions coming or (b) some regions have been moved on
547 // the secondary_free_list.
548 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
549 }
550
551 if (G1ConcRegionFreeingVerbose) {
552 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
553 "could not allocate from secondary_free_list");
554 }
555 return NULL;
556 }
557
558 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
559 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
560 "the only time we use this to allocate a humongous region is "
561 "when we are allocating a single humongous region");
562
563 HeapRegion* res;
564 if (G1StressConcRegionFreeing) {
565 if (!_secondary_free_list.is_empty()) {
566 if (G1ConcRegionFreeingVerbose) {
567 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
568 "forced to look at the secondary_free_list");
569 }
570 res = new_region_try_secondary_free_list(is_old);
571 if (res != NULL) {
572 return res;
573 }
574 }
575 }
576
577 res = _free_list.remove_region(is_old);
578
579 if (res == NULL) {
580 if (G1ConcRegionFreeingVerbose) {
581 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
582 "res == NULL, trying the secondary_free_list");
583 }
584 res = new_region_try_secondary_free_list(is_old);
585 }
586 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
587 // Currently, only attempts to allocate GC alloc regions set
588 // do_expand to true. So, we should only reach here during a
589 // safepoint. If this assumption changes we might have to
590 // reconsider the use of _expand_heap_after_alloc_failure.
591 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
592
593 ergo_verbose1(ErgoHeapSizing,
594 "attempt heap expansion",
595 ergo_format_reason("region allocation request failed")
596 ergo_format_byte("allocation request"),
597 word_size * HeapWordSize);
598 if (expand(word_size * HeapWordSize)) {
599 // Given that expand() succeeded in expanding the heap, and we
600 // always expand the heap by an amount aligned to the heap
601 // region size, the free list should in theory not be empty.
602 // In either case remove_region() will check for NULL.
603 res = _free_list.remove_region(is_old);
604 } else {
605 _expand_heap_after_alloc_failure = false;
606 }
607 }
608 return res;
609 }
610
611 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
612 size_t word_size) {
613 assert(isHumongous(word_size), "word_size should be humongous");
614 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
615
616 uint first = G1_NULL_HRS_INDEX;
617 if (num_regions == 1) {
618 // Only one region to allocate, no need to go through the slower
619 // path. The caller will attempt the expansion if this fails, so
620 // let's not try to expand here too.
621 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
622 if (hr != NULL) {
623 first = hr->hrs_index();
624 } else {
625 first = G1_NULL_HRS_INDEX;
626 }
627 } else {
628 // We can't allocate humongous regions while cleanupComplete() is
629 // running, since some of the regions we find to be empty might not
630 // yet be added to the free list and it is not straightforward to
631 // know which list they are on so that we can remove them. Note
632 // that we only need to do this if we need to allocate more than
633 // one region to satisfy the current humongous allocation
634 // request. If we are only allocating one region we use the common
635 // region allocation code (see above).
636 wait_while_free_regions_coming();
637 append_secondary_free_list_if_not_empty_with_lock();
638
639 if (free_regions() >= num_regions) {
640 first = _hrs.find_contiguous(num_regions);
641 if (first != G1_NULL_HRS_INDEX) {
642 for (uint i = first; i < first + num_regions; ++i) {
643 HeapRegion* hr = region_at(i);
644 assert(hr->is_empty(), "sanity");
645 assert(is_on_master_free_list(hr), "sanity");
646 hr->set_pending_removal(true);
647 }
648 _free_list.remove_all_pending(num_regions);
649 }
650 }
651 }
652 return first;
653 }
654
655 HeapWord*
656 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
657 uint num_regions,
658 size_t word_size) {
659 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
660 assert(isHumongous(word_size), "word_size should be humongous");
661 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
662
663 // Index of last region in the series + 1.
664 uint last = first + num_regions;
665
666 // We need to initialize the region(s) we just discovered. This is
667 // a bit tricky given that it can happen concurrently with
668 // refinement threads refining cards on these regions and
669 // potentially wanting to refine the BOT as they are scanning
670 // those cards (this can happen shortly after a cleanup; see CR
671 // 6991377). So we have to set up the region(s) carefully and in
672 // a specific order.
673
674 // The word size sum of all the regions we will allocate.
675 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
676 assert(word_size <= word_size_sum, "sanity");
677
678 // This will be the "starts humongous" region.
679 HeapRegion* first_hr = region_at(first);
680 // The header of the new object will be placed at the bottom of
681 // the first region.
682 HeapWord* new_obj = first_hr->bottom();
683 // This will be the new end of the first region in the series that
684 // should also match the end of the last region in the series.
685 HeapWord* new_end = new_obj + word_size_sum;
686 // This will be the new top of the first region that will reflect
687 // this allocation.
688 HeapWord* new_top = new_obj + word_size;
689
690 // First, we need to zero the header of the space that we will be
691 // allocating. When we update top further down, some refinement
692 // threads might try to scan the region. By zeroing the header we
693 // ensure that any thread that will try to scan the region will
694 // come across the zero klass word and bail out.
695 //
696 // NOTE: It would not have been correct to have used
697 // CollectedHeap::fill_with_object() and make the space look like
698 // an int array. The thread that is doing the allocation will
699 // later update the object header to a potentially different array
700 // type and, for a very short period of time, the klass and length
701 // fields will be inconsistent. This could cause a refinement
702 // thread to calculate the object size incorrectly.
703 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
704
705 // We will set up the first region as "starts humongous". This
706 // will also update the BOT covering all the regions to reflect
707 // that there is a single object that starts at the bottom of the
708 // first region.
709 first_hr->set_startsHumongous(new_top, new_end);
710
711 // Then, if there are any, we will set up the "continues
712 // humongous" regions.
713 HeapRegion* hr = NULL;
714 for (uint i = first + 1; i < last; ++i) {
715 hr = region_at(i);
716 hr->set_continuesHumongous(first_hr);
717 }
718 // If we have "continues humongous" regions (hr != NULL), then the
719 // end of the last one should match new_end.
720 assert(hr == NULL || hr->end() == new_end, "sanity");
721
722 // Up to this point no concurrent thread would have been able to
723 // do any scanning on any region in this series. All the top
724 // fields still point to bottom, so the intersection between
725 // [bottom,top] and [card_start,card_end] will be empty. Before we
726 // update the top fields, we'll do a storestore to make sure that
727 // no thread sees the update to top before the zeroing of the
728 // object header and the BOT initialization.
729 OrderAccess::storestore();
730
731 // Now that the BOT and the object header have been initialized,
732 // we can update top of the "starts humongous" region.
733 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
734 "new_top should be in this region");
735 first_hr->set_top(new_top);
736 if (_hr_printer.is_active()) {
737 HeapWord* bottom = first_hr->bottom();
738 HeapWord* end = first_hr->orig_end();
739 if ((first + 1) == last) {
740 // the series has a single humongous region
741 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
742 } else {
743 // the series has more than one humongous regions
744 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
745 }
746 }
747
748 // Now, we will update the top fields of the "continues humongous"
749 // regions. The reason we need to do this is that, otherwise,
750 // these regions would look empty and this will confuse parts of
751 // G1. For example, the code that looks for a consecutive number
752 // of empty regions will consider them empty and try to
753 // re-allocate them. We can extend is_empty() to also include
754 // !continuesHumongous(), but it is easier to just update the top
755 // fields here. The way we set top for all regions (i.e., top ==
756 // end for all regions but the last one, top == new_top for the
757 // last one) is actually used when we will free up the humongous
758 // region in free_humongous_region().
759 hr = NULL;
760 for (uint i = first + 1; i < last; ++i) {
761 hr = region_at(i);
762 if ((i + 1) == last) {
763 // last continues humongous region
764 assert(hr->bottom() < new_top && new_top <= hr->end(),
765 "new_top should fall on this region");
766 hr->set_top(new_top);
767 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
768 } else {
769 // not last one
770 assert(new_top > hr->end(), "new_top should be above this region");
771 hr->set_top(hr->end());
772 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
773 }
774 }
775 // If we have continues humongous regions (hr != NULL), then the
776 // end of the last one should match new_end and its top should
777 // match new_top.
778 assert(hr == NULL ||
779 (hr->end() == new_end && hr->top() == new_top), "sanity");
780
781 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
782 _summary_bytes_used += first_hr->used();
783 _humongous_set.add(first_hr);
784
785 return new_obj;
786 }
787
788 // If could fit into free regions w/o expansion, try.
789 // Otherwise, if can expand, do so.
790 // Otherwise, if using ex regions might help, try with ex given back.
791 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
792 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
793
794 verify_region_sets_optional();
795
796 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
797 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
798 uint x_num = expansion_regions();
799 uint fs = _hrs.free_suffix();
800 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
801 if (first == G1_NULL_HRS_INDEX) {
802 // The only thing we can do now is attempt expansion.
803 if (fs + x_num >= num_regions) {
804 // If the number of regions we're trying to allocate for this
805 // object is at most the number of regions in the free suffix,
806 // then the call to humongous_obj_allocate_find_first() above
807 // should have succeeded and we wouldn't be here.
808 //
809 // We should only be trying to expand when the free suffix is
810 // not sufficient for the object _and_ we have some expansion
811 // room available.
812 assert(num_regions > fs, "earlier allocation should have succeeded");
813
814 ergo_verbose1(ErgoHeapSizing,
815 "attempt heap expansion",
816 ergo_format_reason("humongous allocation request failed")
817 ergo_format_byte("allocation request"),
818 word_size * HeapWordSize);
819 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
820 // Even though the heap was expanded, it might not have
821 // reached the desired size. So, we cannot assume that the
822 // allocation will succeed.
823 first = humongous_obj_allocate_find_first(num_regions, word_size);
824 }
825 }
826 }
827
828 HeapWord* result = NULL;
829 if (first != G1_NULL_HRS_INDEX) {
830 result =
831 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
832 assert(result != NULL, "it should always return a valid result");
833
834 // A successful humongous object allocation changes the used space
835 // information of the old generation so we need to recalculate the
836 // sizes and update the jstat counters here.
837 g1mm()->update_sizes();
838 }
839
840 verify_region_sets_optional();
841
842 return result;
843 }
844
845 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
846 assert_heap_not_locked_and_not_at_safepoint();
847 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
848
849 unsigned int dummy_gc_count_before;
850 int dummy_gclocker_retry_count = 0;
851 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
852 }
853
854 HeapWord*
855 G1CollectedHeap::mem_allocate(size_t word_size,
856 bool* gc_overhead_limit_was_exceeded) {
857 assert_heap_not_locked_and_not_at_safepoint();
858
859 // Loop until the allocation is satisfied, or unsatisfied after GC.
860 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
861 unsigned int gc_count_before;
862
863 HeapWord* result = NULL;
864 if (!isHumongous(word_size)) {
865 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
866 } else {
867 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
868 }
869 if (result != NULL) {
870 return result;
871 }
872
873 // Create the garbage collection operation...
874 VM_G1CollectForAllocation op(gc_count_before, word_size);
875 // ...and get the VM thread to execute it.
876 VMThread::execute(&op);
877
878 if (op.prologue_succeeded() && op.pause_succeeded()) {
879 // If the operation was successful we'll return the result even
880 // if it is NULL. If the allocation attempt failed immediately
881 // after a Full GC, it's unlikely we'll be able to allocate now.
882 HeapWord* result = op.result();
883 if (result != NULL && !isHumongous(word_size)) {
884 // Allocations that take place on VM operations do not do any
885 // card dirtying and we have to do it here. We only have to do
886 // this for non-humongous allocations, though.
887 dirty_young_block(result, word_size);
888 }
889 return result;
890 } else {
891 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
892 return NULL;
893 }
894 assert(op.result() == NULL,
895 "the result should be NULL if the VM op did not succeed");
896 }
897
898 // Give a warning if we seem to be looping forever.
899 if ((QueuedAllocationWarningCount > 0) &&
900 (try_count % QueuedAllocationWarningCount == 0)) {
901 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
902 }
903 }
904
905 ShouldNotReachHere();
906 return NULL;
907 }
908
909 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
910 unsigned int *gc_count_before_ret,
911 int* gclocker_retry_count_ret) {
912 // Make sure you read the note in attempt_allocation_humongous().
913
914 assert_heap_not_locked_and_not_at_safepoint();
915 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
916 "be called for humongous allocation requests");
917
918 // We should only get here after the first-level allocation attempt
919 // (attempt_allocation()) failed to allocate.
920
921 // We will loop until a) we manage to successfully perform the
922 // allocation or b) we successfully schedule a collection which
923 // fails to perform the allocation. b) is the only case when we'll
924 // return NULL.
925 HeapWord* result = NULL;
926 for (int try_count = 1; /* we'll return */; try_count += 1) {
927 bool should_try_gc;
928 unsigned int gc_count_before;
929
930 {
931 MutexLockerEx x(Heap_lock);
932
933 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
934 false /* bot_updates */);
935 if (result != NULL) {
936 return result;
937 }
938
939 // If we reach here, attempt_allocation_locked() above failed to
940 // allocate a new region. So the mutator alloc region should be NULL.
941 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
942
943 if (GC_locker::is_active_and_needs_gc()) {
944 if (g1_policy()->can_expand_young_list()) {
945 // No need for an ergo verbose message here,
946 // can_expand_young_list() does this when it returns true.
947 result = _mutator_alloc_region.attempt_allocation_force(word_size,
948 false /* bot_updates */);
949 if (result != NULL) {
950 return result;
951 }
952 }
953 should_try_gc = false;
954 } else {
955 // The GCLocker may not be active but the GCLocker initiated
956 // GC may not yet have been performed (GCLocker::needs_gc()
957 // returns true). In this case we do not try this GC and
958 // wait until the GCLocker initiated GC is performed, and
959 // then retry the allocation.
960 if (GC_locker::needs_gc()) {
961 should_try_gc = false;
962 } else {
963 // Read the GC count while still holding the Heap_lock.
964 gc_count_before = total_collections();
965 should_try_gc = true;
966 }
967 }
968 }
969
970 if (should_try_gc) {
971 bool succeeded;
972 result = do_collection_pause(word_size, gc_count_before, &succeeded,
973 GCCause::_g1_inc_collection_pause);
974 if (result != NULL) {
975 assert(succeeded, "only way to get back a non-NULL result");
976 return result;
977 }
978
979 if (succeeded) {
980 // If we get here we successfully scheduled a collection which
981 // failed to allocate. No point in trying to allocate
982 // further. We'll just return NULL.
983 MutexLockerEx x(Heap_lock);
984 *gc_count_before_ret = total_collections();
985 return NULL;
986 }
987 } else {
988 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
989 MutexLockerEx x(Heap_lock);
990 *gc_count_before_ret = total_collections();
991 return NULL;
992 }
993 // The GCLocker is either active or the GCLocker initiated
994 // GC has not yet been performed. Stall until it is and
995 // then retry the allocation.
996 GC_locker::stall_until_clear();
997 (*gclocker_retry_count_ret) += 1;
998 }
999
1000 // We can reach here if we were unsuccessful in scheduling a
1001 // collection (because another thread beat us to it) or if we were
1002 // stalled due to the GC locker. In either can we should retry the
1003 // allocation attempt in case another thread successfully
1004 // performed a collection and reclaimed enough space. We do the
1005 // first attempt (without holding the Heap_lock) here and the
1006 // follow-on attempt will be at the start of the next loop
1007 // iteration (after taking the Heap_lock).
1008 result = _mutator_alloc_region.attempt_allocation(word_size,
1009 false /* bot_updates */);
1010 if (result != NULL) {
1011 return result;
1012 }
1013
1014 // Give a warning if we seem to be looping forever.
1015 if ((QueuedAllocationWarningCount > 0) &&
1016 (try_count % QueuedAllocationWarningCount == 0)) {
1017 warning("G1CollectedHeap::attempt_allocation_slow() "
1018 "retries %d times", try_count);
1019 }
1020 }
1021
1022 ShouldNotReachHere();
1023 return NULL;
1024 }
1025
1026 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1027 unsigned int * gc_count_before_ret,
1028 int* gclocker_retry_count_ret) {
1029 // The structure of this method has a lot of similarities to
1030 // attempt_allocation_slow(). The reason these two were not merged
1031 // into a single one is that such a method would require several "if
1032 // allocation is not humongous do this, otherwise do that"
1033 // conditional paths which would obscure its flow. In fact, an early
1034 // version of this code did use a unified method which was harder to
1035 // follow and, as a result, it had subtle bugs that were hard to
1036 // track down. So keeping these two methods separate allows each to
1037 // be more readable. It will be good to keep these two in sync as
1038 // much as possible.
1039
1040 assert_heap_not_locked_and_not_at_safepoint();
1041 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1042 "should only be called for humongous allocations");
1043
1044 // Humongous objects can exhaust the heap quickly, so we should check if we
1045 // need to start a marking cycle at each humongous object allocation. We do
1046 // the check before we do the actual allocation. The reason for doing it
1047 // before the allocation is that we avoid having to keep track of the newly
1048 // allocated memory while we do a GC.
1049 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1050 word_size)) {
1051 collect(GCCause::_g1_humongous_allocation);
1052 }
1053
1054 // We will loop until a) we manage to successfully perform the
1055 // allocation or b) we successfully schedule a collection which
1056 // fails to perform the allocation. b) is the only case when we'll
1057 // return NULL.
1058 HeapWord* result = NULL;
1059 for (int try_count = 1; /* we'll return */; try_count += 1) {
1060 bool should_try_gc;
1061 unsigned int gc_count_before;
1062
1063 {
1064 MutexLockerEx x(Heap_lock);
1065
1066 // Given that humongous objects are not allocated in young
1067 // regions, we'll first try to do the allocation without doing a
1068 // collection hoping that there's enough space in the heap.
1069 result = humongous_obj_allocate(word_size);
1070 if (result != NULL) {
1071 return result;
1072 }
1073
1074 if (GC_locker::is_active_and_needs_gc()) {
1075 should_try_gc = false;
1076 } else {
1077 // The GCLocker may not be active but the GCLocker initiated
1078 // GC may not yet have been performed (GCLocker::needs_gc()
1079 // returns true). In this case we do not try this GC and
1080 // wait until the GCLocker initiated GC is performed, and
1081 // then retry the allocation.
1082 if (GC_locker::needs_gc()) {
1083 should_try_gc = false;
1084 } else {
1085 // Read the GC count while still holding the Heap_lock.
1086 gc_count_before = total_collections();
1087 should_try_gc = true;
1088 }
1089 }
1090 }
1091
1092 if (should_try_gc) {
1093 // If we failed to allocate the humongous object, we should try to
1094 // do a collection pause (if we're allowed) in case it reclaims
1095 // enough space for the allocation to succeed after the pause.
1096
1097 bool succeeded;
1098 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1099 GCCause::_g1_humongous_allocation);
1100 if (result != NULL) {
1101 assert(succeeded, "only way to get back a non-NULL result");
1102 return result;
1103 }
1104
1105 if (succeeded) {
1106 // If we get here we successfully scheduled a collection which
1107 // failed to allocate. No point in trying to allocate
1108 // further. We'll just return NULL.
1109 MutexLockerEx x(Heap_lock);
1110 *gc_count_before_ret = total_collections();
1111 return NULL;
1112 }
1113 } else {
1114 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1115 MutexLockerEx x(Heap_lock);
1116 *gc_count_before_ret = total_collections();
1117 return NULL;
1118 }
1119 // The GCLocker is either active or the GCLocker initiated
1120 // GC has not yet been performed. Stall until it is and
1121 // then retry the allocation.
1122 GC_locker::stall_until_clear();
1123 (*gclocker_retry_count_ret) += 1;
1124 }
1125
1126 // We can reach here if we were unsuccessful in scheduling a
1127 // collection (because another thread beat us to it) or if we were
1128 // stalled due to the GC locker. In either can we should retry the
1129 // allocation attempt in case another thread successfully
1130 // performed a collection and reclaimed enough space. Give a
1131 // warning if we seem to be looping forever.
1132
1133 if ((QueuedAllocationWarningCount > 0) &&
1134 (try_count % QueuedAllocationWarningCount == 0)) {
1135 warning("G1CollectedHeap::attempt_allocation_humongous() "
1136 "retries %d times", try_count);
1137 }
1138 }
1139
1140 ShouldNotReachHere();
1141 return NULL;
1142 }
1143
1144 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1145 bool expect_null_mutator_alloc_region) {
1146 assert_at_safepoint(true /* should_be_vm_thread */);
1147 assert(_mutator_alloc_region.get() == NULL ||
1148 !expect_null_mutator_alloc_region,
1149 "the current alloc region was unexpectedly found to be non-NULL");
1150
1151 if (!isHumongous(word_size)) {
1152 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1153 false /* bot_updates */);
1154 } else {
1155 HeapWord* result = humongous_obj_allocate(word_size);
1156 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1157 g1_policy()->set_initiate_conc_mark_if_possible();
1158 }
1159 return result;
1160 }
1161
1162 ShouldNotReachHere();
1163 }
1164
1165 class PostMCRemSetClearClosure: public HeapRegionClosure {
1166 G1CollectedHeap* _g1h;
1167 ModRefBarrierSet* _mr_bs;
1168 public:
1169 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1170 _g1h(g1h), _mr_bs(mr_bs) {}
1171
1172 bool doHeapRegion(HeapRegion* r) {
1173 HeapRegionRemSet* hrrs = r->rem_set();
1174
1175 if (r->continuesHumongous()) {
1176 // We'll assert that the strong code root list and RSet is empty
1177 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1178 assert(hrrs->occupied() == 0, "RSet should be empty");
1179 return false;
1180 }
1181
1182 _g1h->reset_gc_time_stamps(r);
1183 hrrs->clear();
1184 // You might think here that we could clear just the cards
1185 // corresponding to the used region. But no: if we leave a dirty card
1186 // in a region we might allocate into, then it would prevent that card
1187 // from being enqueued, and cause it to be missed.
1188 // Re: the performance cost: we shouldn't be doing full GC anyway!
1189 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1190
1191 return false;
1192 }
1193 };
1194
1195 void G1CollectedHeap::clear_rsets_post_compaction() {
1196 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1197 heap_region_iterate(&rs_clear);
1198 }
1199
1200 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1201 G1CollectedHeap* _g1h;
1202 UpdateRSOopClosure _cl;
1203 int _worker_i;
1204 public:
1205 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1206 _cl(g1->g1_rem_set(), worker_i),
1207 _worker_i(worker_i),
1208 _g1h(g1)
1209 { }
1210
1211 bool doHeapRegion(HeapRegion* r) {
1212 if (!r->continuesHumongous()) {
1213 _cl.set_from(r);
1214 r->oop_iterate(&_cl);
1215 }
1216 return false;
1217 }
1218 };
1219
1220 class ParRebuildRSTask: public AbstractGangTask {
1221 G1CollectedHeap* _g1;
1222 public:
1223 ParRebuildRSTask(G1CollectedHeap* g1)
1224 : AbstractGangTask("ParRebuildRSTask"),
1225 _g1(g1)
1226 { }
1227
1228 void work(uint worker_id) {
1229 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1230 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1231 _g1->workers()->active_workers(),
1232 HeapRegion::RebuildRSClaimValue);
1233 }
1234 };
1235
1236 class PostCompactionPrinterClosure: public HeapRegionClosure {
1237 private:
1238 G1HRPrinter* _hr_printer;
1239 public:
1240 bool doHeapRegion(HeapRegion* hr) {
1241 assert(!hr->is_young(), "not expecting to find young regions");
1242 // We only generate output for non-empty regions.
1243 if (!hr->is_empty()) {
1244 if (!hr->isHumongous()) {
1245 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1246 } else if (hr->startsHumongous()) {
1247 if (hr->region_num() == 1) {
1248 // single humongous region
1249 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1250 } else {
1251 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1252 }
1253 } else {
1254 assert(hr->continuesHumongous(), "only way to get here");
1255 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1256 }
1257 }
1258 return false;
1259 }
1260
1261 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1262 : _hr_printer(hr_printer) { }
1263 };
1264
1265 void G1CollectedHeap::print_hrs_post_compaction() {
1266 PostCompactionPrinterClosure cl(hr_printer());
1267 heap_region_iterate(&cl);
1268 }
1269
1270 bool G1CollectedHeap::do_collection(bool explicit_gc,
1271 bool clear_all_soft_refs,
1272 size_t word_size) {
1273 assert_at_safepoint(true /* should_be_vm_thread */);
1274
1275 if (GC_locker::check_active_before_gc()) {
1276 return false;
1277 }
1278
1279 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1280 gc_timer->register_gc_start();
1281
1282 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1283 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1284
1285 SvcGCMarker sgcm(SvcGCMarker::FULL);
1286 ResourceMark rm;
1287
1288 print_heap_before_gc();
1289 trace_heap_before_gc(gc_tracer);
1290
1291 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1292
1293 verify_region_sets_optional();
1294
1295 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1296 collector_policy()->should_clear_all_soft_refs();
1297
1298 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1299
1300 {
1301 IsGCActiveMark x;
1302
1303 // Timing
1304 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1305 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1306 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1307
1308 {
1309 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1310 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1311 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1312
1313 double start = os::elapsedTime();
1314 g1_policy()->record_full_collection_start();
1315
1316 // Note: When we have a more flexible GC logging framework that
1317 // allows us to add optional attributes to a GC log record we
1318 // could consider timing and reporting how long we wait in the
1319 // following two methods.
1320 wait_while_free_regions_coming();
1321 // If we start the compaction before the CM threads finish
1322 // scanning the root regions we might trip them over as we'll
1323 // be moving objects / updating references. So let's wait until
1324 // they are done. By telling them to abort, they should complete
1325 // early.
1326 _cm->root_regions()->abort();
1327 _cm->root_regions()->wait_until_scan_finished();
1328 append_secondary_free_list_if_not_empty_with_lock();
1329
1330 gc_prologue(true);
1331 increment_total_collections(true /* full gc */);
1332 increment_old_marking_cycles_started();
1333
1334 assert(used() == recalculate_used(), "Should be equal");
1335
1336 verify_before_gc();
1337
1338 pre_full_gc_dump(gc_timer);
1339
1340 COMPILER2_PRESENT(DerivedPointerTable::clear());
1341
1342 // Disable discovery and empty the discovered lists
1343 // for the CM ref processor.
1344 ref_processor_cm()->disable_discovery();
1345 ref_processor_cm()->abandon_partial_discovery();
1346 ref_processor_cm()->verify_no_references_recorded();
1347
1348 // Abandon current iterations of concurrent marking and concurrent
1349 // refinement, if any are in progress. We have to do this before
1350 // wait_until_scan_finished() below.
1351 concurrent_mark()->abort();
1352
1353 // Make sure we'll choose a new allocation region afterwards.
1354 release_mutator_alloc_region();
1355 abandon_gc_alloc_regions();
1356 g1_rem_set()->cleanupHRRS();
1357
1358 // We should call this after we retire any currently active alloc
1359 // regions so that all the ALLOC / RETIRE events are generated
1360 // before the start GC event.
1361 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1362
1363 // We may have added regions to the current incremental collection
1364 // set between the last GC or pause and now. We need to clear the
1365 // incremental collection set and then start rebuilding it afresh
1366 // after this full GC.
1367 abandon_collection_set(g1_policy()->inc_cset_head());
1368 g1_policy()->clear_incremental_cset();
1369 g1_policy()->stop_incremental_cset_building();
1370
1371 tear_down_region_sets(false /* free_list_only */);
1372 g1_policy()->set_gcs_are_young(true);
1373
1374 // See the comments in g1CollectedHeap.hpp and
1375 // G1CollectedHeap::ref_processing_init() about
1376 // how reference processing currently works in G1.
1377
1378 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1379 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1380
1381 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1382 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1383
1384 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1385 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1386
1387 // Do collection work
1388 {
1389 HandleMark hm; // Discard invalid handles created during gc
1390 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1391 }
1392
1393 assert(free_regions() == 0, "we should not have added any free regions");
1394 rebuild_region_sets(false /* free_list_only */);
1395
1396 // Enqueue any discovered reference objects that have
1397 // not been removed from the discovered lists.
1398 ref_processor_stw()->enqueue_discovered_references();
1399
1400 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1401
1402 MemoryService::track_memory_usage();
1403
1404 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1405 ref_processor_stw()->verify_no_references_recorded();
1406
1407 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1408 ClassLoaderDataGraph::purge();
1409 MetaspaceAux::verify_metrics();
1410
1411 // Note: since we've just done a full GC, concurrent
1412 // marking is no longer active. Therefore we need not
1413 // re-enable reference discovery for the CM ref processor.
1414 // That will be done at the start of the next marking cycle.
1415 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1416 ref_processor_cm()->verify_no_references_recorded();
1417
1418 reset_gc_time_stamp();
1419 // Since everything potentially moved, we will clear all remembered
1420 // sets, and clear all cards. Later we will rebuild remembered
1421 // sets. We will also reset the GC time stamps of the regions.
1422 clear_rsets_post_compaction();
1423 check_gc_time_stamps();
1424
1425 // Resize the heap if necessary.
1426 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1427
1428 if (_hr_printer.is_active()) {
1429 // We should do this after we potentially resize the heap so
1430 // that all the COMMIT / UNCOMMIT events are generated before
1431 // the end GC event.
1432
1433 print_hrs_post_compaction();
1434 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1435 }
1436
1437 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1438 if (hot_card_cache->use_cache()) {
1439 hot_card_cache->reset_card_counts();
1440 hot_card_cache->reset_hot_cache();
1441 }
1442
1443 // Rebuild remembered sets of all regions.
1444 if (G1CollectedHeap::use_parallel_gc_threads()) {
1445 uint n_workers =
1446 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1447 workers()->active_workers(),
1448 Threads::number_of_non_daemon_threads());
1449 assert(UseDynamicNumberOfGCThreads ||
1450 n_workers == workers()->total_workers(),
1451 "If not dynamic should be using all the workers");
1452 workers()->set_active_workers(n_workers);
1453 // Set parallel threads in the heap (_n_par_threads) only
1454 // before a parallel phase and always reset it to 0 after
1455 // the phase so that the number of parallel threads does
1456 // no get carried forward to a serial phase where there
1457 // may be code that is "possibly_parallel".
1458 set_par_threads(n_workers);
1459
1460 ParRebuildRSTask rebuild_rs_task(this);
1461 assert(check_heap_region_claim_values(
1462 HeapRegion::InitialClaimValue), "sanity check");
1463 assert(UseDynamicNumberOfGCThreads ||
1464 workers()->active_workers() == workers()->total_workers(),
1465 "Unless dynamic should use total workers");
1466 // Use the most recent number of active workers
1467 assert(workers()->active_workers() > 0,
1468 "Active workers not properly set");
1469 set_par_threads(workers()->active_workers());
1470 workers()->run_task(&rebuild_rs_task);
1471 set_par_threads(0);
1472 assert(check_heap_region_claim_values(
1473 HeapRegion::RebuildRSClaimValue), "sanity check");
1474 reset_heap_region_claim_values();
1475 } else {
1476 RebuildRSOutOfRegionClosure rebuild_rs(this);
1477 heap_region_iterate(&rebuild_rs);
1478 }
1479
1480 // Rebuild the strong code root lists for each region
1481 rebuild_strong_code_roots();
1482
1483 if (true) { // FIXME
1484 MetaspaceGC::compute_new_size();
1485 }
1486
1487 #ifdef TRACESPINNING
1488 ParallelTaskTerminator::print_termination_counts();
1489 #endif
1490
1491 // Discard all rset updates
1492 JavaThread::dirty_card_queue_set().abandon_logs();
1493 assert(!G1DeferredRSUpdate
1494 || (G1DeferredRSUpdate &&
1495 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1496
1497 _young_list->reset_sampled_info();
1498 // At this point there should be no regions in the
1499 // entire heap tagged as young.
1500 assert(check_young_list_empty(true /* check_heap */),
1501 "young list should be empty at this point");
1502
1503 // Update the number of full collections that have been completed.
1504 increment_old_marking_cycles_completed(false /* concurrent */);
1505
1506 _hrs.verify_optional();
1507 verify_region_sets_optional();
1508
1509 verify_after_gc();
1510
1511 // Start a new incremental collection set for the next pause
1512 assert(g1_policy()->collection_set() == NULL, "must be");
1513 g1_policy()->start_incremental_cset_building();
1514
1515 // Clear the _cset_fast_test bitmap in anticipation of adding
1516 // regions to the incremental collection set for the next
1517 // evacuation pause.
1518 clear_cset_fast_test();
1519
1520 init_mutator_alloc_region();
1521
1522 double end = os::elapsedTime();
1523 g1_policy()->record_full_collection_end();
1524
1525 if (G1Log::fine()) {
1526 g1_policy()->print_heap_transition();
1527 }
1528
1529 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1530 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1531 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1532 // before any GC notifications are raised.
1533 g1mm()->update_sizes();
1534
1535 gc_epilogue(true);
1536 }
1537
1538 if (G1Log::finer()) {
1539 g1_policy()->print_detailed_heap_transition(true /* full */);
1540 }
1541
1542 print_heap_after_gc();
1543 trace_heap_after_gc(gc_tracer);
1544
1545 post_full_gc_dump(gc_timer);
1546
1547 gc_timer->register_gc_end();
1548 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1549 }
1550
1551 return true;
1552 }
1553
1554 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1555 // do_collection() will return whether it succeeded in performing
1556 // the GC. Currently, there is no facility on the
1557 // do_full_collection() API to notify the caller than the collection
1558 // did not succeed (e.g., because it was locked out by the GC
1559 // locker). So, right now, we'll ignore the return value.
1560 bool dummy = do_collection(true, /* explicit_gc */
1561 clear_all_soft_refs,
1562 0 /* word_size */);
1563 }
1564
1565 // This code is mostly copied from TenuredGeneration.
1566 void
1567 G1CollectedHeap::
1568 resize_if_necessary_after_full_collection(size_t word_size) {
1569 // Include the current allocation, if any, and bytes that will be
1570 // pre-allocated to support collections, as "used".
1571 const size_t used_after_gc = used();
1572 const size_t capacity_after_gc = capacity();
1573 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1574
1575 // This is enforced in arguments.cpp.
1576 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1577 "otherwise the code below doesn't make sense");
1578
1579 // We don't have floating point command-line arguments
1580 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1581 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1582 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1583 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1584
1585 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1586 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1587
1588 // We have to be careful here as these two calculations can overflow
1589 // 32-bit size_t's.
1590 double used_after_gc_d = (double) used_after_gc;
1591 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1592 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1593
1594 // Let's make sure that they are both under the max heap size, which
1595 // by default will make them fit into a size_t.
1596 double desired_capacity_upper_bound = (double) max_heap_size;
1597 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1598 desired_capacity_upper_bound);
1599 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1600 desired_capacity_upper_bound);
1601
1602 // We can now safely turn them into size_t's.
1603 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1604 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1605
1606 // This assert only makes sense here, before we adjust them
1607 // with respect to the min and max heap size.
1608 assert(minimum_desired_capacity <= maximum_desired_capacity,
1609 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1610 "maximum_desired_capacity = "SIZE_FORMAT,
1611 minimum_desired_capacity, maximum_desired_capacity));
1612
1613 // Should not be greater than the heap max size. No need to adjust
1614 // it with respect to the heap min size as it's a lower bound (i.e.,
1615 // we'll try to make the capacity larger than it, not smaller).
1616 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1617 // Should not be less than the heap min size. No need to adjust it
1618 // with respect to the heap max size as it's an upper bound (i.e.,
1619 // we'll try to make the capacity smaller than it, not greater).
1620 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1621
1622 if (capacity_after_gc < minimum_desired_capacity) {
1623 // Don't expand unless it's significant
1624 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1625 ergo_verbose4(ErgoHeapSizing,
1626 "attempt heap expansion",
1627 ergo_format_reason("capacity lower than "
1628 "min desired capacity after Full GC")
1629 ergo_format_byte("capacity")
1630 ergo_format_byte("occupancy")
1631 ergo_format_byte_perc("min desired capacity"),
1632 capacity_after_gc, used_after_gc,
1633 minimum_desired_capacity, (double) MinHeapFreeRatio);
1634 expand(expand_bytes);
1635
1636 // No expansion, now see if we want to shrink
1637 } else if (capacity_after_gc > maximum_desired_capacity) {
1638 // Capacity too large, compute shrinking size
1639 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1640 ergo_verbose4(ErgoHeapSizing,
1641 "attempt heap shrinking",
1642 ergo_format_reason("capacity higher than "
1643 "max desired capacity after Full GC")
1644 ergo_format_byte("capacity")
1645 ergo_format_byte("occupancy")
1646 ergo_format_byte_perc("max desired capacity"),
1647 capacity_after_gc, used_after_gc,
1648 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1649 shrink(shrink_bytes);
1650 }
1651 }
1652
1653
1654 HeapWord*
1655 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1656 bool* succeeded) {
1657 assert_at_safepoint(true /* should_be_vm_thread */);
1658
1659 *succeeded = true;
1660 // Let's attempt the allocation first.
1661 HeapWord* result =
1662 attempt_allocation_at_safepoint(word_size,
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);
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 true /* expect_null_mutator_alloc_region */);
1691 if (result != NULL) {
1692 assert(*succeeded, "sanity");
1693 return result;
1694 }
1695
1696 // Then, try a Full GC that will collect all soft references.
1697 gc_succeeded = do_collection(false, /* explicit_gc */
1698 true, /* clear_all_soft_refs */
1699 word_size);
1700 if (!gc_succeeded) {
1701 *succeeded = false;
1702 return NULL;
1703 }
1704
1705 // Retry the allocation once more
1706 result = attempt_allocation_at_safepoint(word_size,
1707 true /* expect_null_mutator_alloc_region */);
1708 if (result != NULL) {
1709 assert(*succeeded, "sanity");
1710 return result;
1711 }
1712
1713 assert(!collector_policy()->should_clear_all_soft_refs(),
1714 "Flag should have been handled and cleared prior to this point");
1715
1716 // What else? We might try synchronous finalization later. If the total
1717 // space available is large enough for the allocation, then a more
1718 // complete compaction phase than we've tried so far might be
1719 // appropriate.
1720 assert(*succeeded, "sanity");
1721 return NULL;
1722 }
1723
1724 // Attempting to expand the heap sufficiently
1725 // to support an allocation of the given "word_size". If
1726 // successful, perform the allocation and return the address of the
1727 // allocated block, or else "NULL".
1728
1729 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1730 assert_at_safepoint(true /* should_be_vm_thread */);
1731
1732 verify_region_sets_optional();
1733
1734 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1735 ergo_verbose1(ErgoHeapSizing,
1736 "attempt heap expansion",
1737 ergo_format_reason("allocation request failed")
1738 ergo_format_byte("allocation request"),
1739 word_size * HeapWordSize);
1740 if (expand(expand_bytes)) {
1741 _hrs.verify_optional();
1742 verify_region_sets_optional();
1743 return attempt_allocation_at_safepoint(word_size,
1744 false /* expect_null_mutator_alloc_region */);
1745 }
1746 return NULL;
1747 }
1748
1749 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1750 HeapWord* new_end) {
1751 assert(old_end != new_end, "don't call this otherwise");
1752 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1753
1754 // Update the committed mem region.
1755 _g1_committed.set_end(new_end);
1756 // Tell the card table about the update.
1757 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1758 // Tell the BOT about the update.
1759 _bot_shared->resize(_g1_committed.word_size());
1760 // Tell the hot card cache about the update
1761 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1762 }
1763
1764 bool G1CollectedHeap::expand(size_t expand_bytes) {
1765 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1766 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1767 HeapRegion::GrainBytes);
1768 ergo_verbose2(ErgoHeapSizing,
1769 "expand the heap",
1770 ergo_format_byte("requested expansion amount")
1771 ergo_format_byte("attempted expansion amount"),
1772 expand_bytes, aligned_expand_bytes);
1773
1774 if (_g1_storage.uncommitted_size() == 0) {
1775 ergo_verbose0(ErgoHeapSizing,
1776 "did not expand the heap",
1777 ergo_format_reason("heap already fully expanded"));
1778 return false;
1779 }
1780
1781 // First commit the memory.
1782 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1783 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1784 if (successful) {
1785 // Then propagate this update to the necessary data structures.
1786 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1787 update_committed_space(old_end, new_end);
1788
1789 FreeRegionList expansion_list("Local Expansion List");
1790 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1791 assert(mr.start() == old_end, "post-condition");
1792 // mr might be a smaller region than what was requested if
1793 // expand_by() was unable to allocate the HeapRegion instances
1794 assert(mr.end() <= new_end, "post-condition");
1795
1796 size_t actual_expand_bytes = mr.byte_size();
1797 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1798 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1799 "post-condition");
1800 if (actual_expand_bytes < aligned_expand_bytes) {
1801 // We could not expand _hrs to the desired size. In this case we
1802 // need to shrink the committed space accordingly.
1803 assert(mr.end() < new_end, "invariant");
1804
1805 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1806 // First uncommit the memory.
1807 _g1_storage.shrink_by(diff_bytes);
1808 // Then propagate this update to the necessary data structures.
1809 update_committed_space(new_end, mr.end());
1810 }
1811 _free_list.add_as_tail(&expansion_list);
1812
1813 if (_hr_printer.is_active()) {
1814 HeapWord* curr = mr.start();
1815 while (curr < mr.end()) {
1816 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1817 _hr_printer.commit(curr, curr_end);
1818 curr = curr_end;
1819 }
1820 assert(curr == mr.end(), "post-condition");
1821 }
1822 g1_policy()->record_new_heap_size(n_regions());
1823 } else {
1824 ergo_verbose0(ErgoHeapSizing,
1825 "did not expand the heap",
1826 ergo_format_reason("heap expansion operation failed"));
1827 // The expansion of the virtual storage space was unsuccessful.
1828 // Let's see if it was because we ran out of swap.
1829 if (G1ExitOnExpansionFailure &&
1830 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1831 // We had head room...
1832 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1833 }
1834 }
1835 return successful;
1836 }
1837
1838 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1839 size_t aligned_shrink_bytes =
1840 ReservedSpace::page_align_size_down(shrink_bytes);
1841 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1842 HeapRegion::GrainBytes);
1843 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1844
1845 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1846 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1847 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1848
1849 ergo_verbose3(ErgoHeapSizing,
1850 "shrink the heap",
1851 ergo_format_byte("requested shrinking amount")
1852 ergo_format_byte("aligned shrinking amount")
1853 ergo_format_byte("attempted shrinking amount"),
1854 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1855 if (num_regions_removed > 0) {
1856 _g1_storage.shrink_by(shrunk_bytes);
1857 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1858
1859 if (_hr_printer.is_active()) {
1860 HeapWord* curr = old_end;
1861 while (curr > new_end) {
1862 HeapWord* curr_end = curr;
1863 curr -= HeapRegion::GrainWords;
1864 _hr_printer.uncommit(curr, curr_end);
1865 }
1866 }
1867
1868 _expansion_regions += num_regions_removed;
1869 update_committed_space(old_end, new_end);
1870 HeapRegionRemSet::shrink_heap(n_regions());
1871 g1_policy()->record_new_heap_size(n_regions());
1872 } else {
1873 ergo_verbose0(ErgoHeapSizing,
1874 "did not shrink the heap",
1875 ergo_format_reason("heap shrinking operation failed"));
1876 }
1877 }
1878
1879 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1880 verify_region_sets_optional();
1881
1882 // We should only reach here at the end of a Full GC which means we
1883 // should not not be holding to any GC alloc regions. The method
1884 // below will make sure of that and do any remaining clean up.
1885 abandon_gc_alloc_regions();
1886
1887 // Instead of tearing down / rebuilding the free lists here, we
1888 // could instead use the remove_all_pending() method on free_list to
1889 // remove only the ones that we need to remove.
1890 tear_down_region_sets(true /* free_list_only */);
1891 shrink_helper(shrink_bytes);
1892 rebuild_region_sets(true /* free_list_only */);
1893
1894 _hrs.verify_optional();
1895 verify_region_sets_optional();
1896 }
1897
1898 // Public methods.
1899
1900 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1901 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1902 #endif // _MSC_VER
1903
1904
1905 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1906 SharedHeap(policy_),
1907 _g1_policy(policy_),
1908 _dirty_card_queue_set(false),
1909 _into_cset_dirty_card_queue_set(false),
1910 _is_alive_closure_cm(this),
1911 _is_alive_closure_stw(this),
1912 _ref_processor_cm(NULL),
1913 _ref_processor_stw(NULL),
1914 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1915 _bot_shared(NULL),
1916 _evac_failure_scan_stack(NULL),
1917 _mark_in_progress(false),
1918 _cg1r(NULL), _summary_bytes_used(0),
1919 _g1mm(NULL),
1920 _refine_cte_cl(NULL),
1921 _full_collection(false),
1922 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1923 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1924 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1925 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1926 _free_regions_coming(false),
1927 _young_list(new YoungList(this)),
1928 _gc_time_stamp(0),
1929 _retained_old_gc_alloc_region(NULL),
1930 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1931 _old_plab_stats(OldPLABSize, PLABWeight),
1932 _expand_heap_after_alloc_failure(true),
1933 _surviving_young_words(NULL),
1934 _old_marking_cycles_started(0),
1935 _old_marking_cycles_completed(0),
1936 _concurrent_cycle_started(false),
1937 _in_cset_fast_test(NULL),
1938 _in_cset_fast_test_base(NULL),
1939 _dirty_cards_region_list(NULL),
1940 _worker_cset_start_region(NULL),
1941 _worker_cset_start_region_time_stamp(NULL),
1942 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1943 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1944 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1945 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1946
1947 _g1h = this;
1948 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1949 vm_exit_during_initialization("Failed necessary allocation.");
1950 }
1951
1952 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1953
1954 int n_queues = MAX2((int)ParallelGCThreads, 1);
1955 _task_queues = new RefToScanQueueSet(n_queues);
1956
1957 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1958 assert(n_rem_sets > 0, "Invariant.");
1959
1960 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1961 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1962 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1963
1964 for (int i = 0; i < n_queues; i++) {
1965 RefToScanQueue* q = new RefToScanQueue();
1966 q->initialize();
1967 _task_queues->register_queue(i, q);
1968 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1969 }
1970 clear_cset_start_regions();
1971
1972 // Initialize the G1EvacuationFailureALot counters and flags.
1973 NOT_PRODUCT(reset_evacuation_should_fail();)
1974
1975 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1976 }
1977
1978 jint G1CollectedHeap::initialize() {
1979 CollectedHeap::pre_initialize();
1980 os::enable_vtime();
1981
1982 G1Log::init();
1983
1984 // Necessary to satisfy locking discipline assertions.
1985
1986 MutexLocker x(Heap_lock);
1987
1988 // We have to initialize the printer before committing the heap, as
1989 // it will be used then.
1990 _hr_printer.set_active(G1PrintHeapRegions);
1991
1992 // While there are no constraints in the GC code that HeapWordSize
1993 // be any particular value, there are multiple other areas in the
1994 // system which believe this to be true (e.g. oop->object_size in some
1995 // cases incorrectly returns the size in wordSize units rather than
1996 // HeapWordSize).
1997 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1998
1999 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2000 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2001 size_t heap_alignment = collector_policy()->heap_alignment();
2002
2003 // Ensure that the sizes are properly aligned.
2004 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2005 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2006 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2007
2008 _cg1r = new ConcurrentG1Refine(this);
2009
2010 // Reserve the maximum.
2011
2012 // When compressed oops are enabled, the preferred heap base
2013 // is calculated by subtracting the requested size from the
2014 // 32Gb boundary and using the result as the base address for
2015 // heap reservation. If the requested size is not aligned to
2016 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2017 // into the ReservedHeapSpace constructor) then the actual
2018 // base of the reserved heap may end up differing from the
2019 // address that was requested (i.e. the preferred heap base).
2020 // If this happens then we could end up using a non-optimal
2021 // compressed oops mode.
2022
2023 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2024 heap_alignment);
2025
2026 // It is important to do this in a way such that concurrent readers can't
2027 // temporarily think something is in the heap. (I've actually seen this
2028 // happen in asserts: DLD.)
2029 _reserved.set_word_size(0);
2030 _reserved.set_start((HeapWord*)heap_rs.base());
2031 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2032
2033 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2034
2035 // Create the gen rem set (and barrier set) for the entire reserved region.
2036 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2037 set_barrier_set(rem_set()->bs());
2038 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2039 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2040 return JNI_ENOMEM;
2041 }
2042
2043 // Also create a G1 rem set.
2044 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2045
2046 // Carve out the G1 part of the heap.
2047
2048 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2049 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2050 g1_rs.size()/HeapWordSize);
2051
2052 _g1_storage.initialize(g1_rs, 0);
2053 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2054 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2055 (HeapWord*) _g1_reserved.end());
2056 assert(_hrs.max_length() == _expansion_regions,
2057 err_msg("max length: %u expansion regions: %u",
2058 _hrs.max_length(), _expansion_regions));
2059
2060 // Do later initialization work for concurrent refinement.
2061 _cg1r->init();
2062
2063 // 6843694 - ensure that the maximum region index can fit
2064 // in the remembered set structures.
2065 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2066 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2067
2068 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2069 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2070 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2071 "too many cards per region");
2072
2073 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2074
2075 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2076 heap_word_size(init_byte_size));
2077
2078 _g1h = this;
2079
2080 _in_cset_fast_test_length = max_regions();
2081 _in_cset_fast_test_base =
2082 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2083
2084 // We're biasing _in_cset_fast_test to avoid subtracting the
2085 // beginning of the heap every time we want to index; basically
2086 // it's the same with what we do with the card table.
2087 _in_cset_fast_test = _in_cset_fast_test_base -
2088 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2089
2090 // Clear the _cset_fast_test bitmap in anticipation of adding
2091 // regions to the incremental collection set for the first
2092 // evacuation pause.
2093 clear_cset_fast_test();
2094
2095 // Create the ConcurrentMark data structure and thread.
2096 // (Must do this late, so that "max_regions" is defined.)
2097 _cm = new ConcurrentMark(this, heap_rs);
2098 if (_cm == NULL || !_cm->completed_initialization()) {
2099 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2100 return JNI_ENOMEM;
2101 }
2102 _cmThread = _cm->cmThread();
2103
2104 // Initialize the from_card cache structure of HeapRegionRemSet.
2105 HeapRegionRemSet::init_heap(max_regions());
2106
2107 // Now expand into the initial heap size.
2108 if (!expand(init_byte_size)) {
2109 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2110 return JNI_ENOMEM;
2111 }
2112
2113 // Perform any initialization actions delegated to the policy.
2114 g1_policy()->init();
2115
2116 _refine_cte_cl =
2117 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2118 g1_rem_set(),
2119 concurrent_g1_refine());
2120 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2121
2122 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2123 SATB_Q_FL_lock,
2124 G1SATBProcessCompletedThreshold,
2125 Shared_SATB_Q_lock);
2126
2127 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2128 DirtyCardQ_FL_lock,
2129 concurrent_g1_refine()->yellow_zone(),
2130 concurrent_g1_refine()->red_zone(),
2131 Shared_DirtyCardQ_lock);
2132
2133 if (G1DeferredRSUpdate) {
2134 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2135 DirtyCardQ_FL_lock,
2136 -1, // never trigger processing
2137 -1, // no limit on length
2138 Shared_DirtyCardQ_lock,
2139 &JavaThread::dirty_card_queue_set());
2140 }
2141
2142 // Initialize the card queue set used to hold cards containing
2143 // references into the collection set.
2144 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2145 DirtyCardQ_FL_lock,
2146 -1, // never trigger processing
2147 -1, // no limit on length
2148 Shared_DirtyCardQ_lock,
2149 &JavaThread::dirty_card_queue_set());
2150
2151 // In case we're keeping closure specialization stats, initialize those
2152 // counts and that mechanism.
2153 SpecializationStats::clear();
2154
2155 // Here we allocate the dummy full region that is required by the
2156 // G1AllocRegion class. If we don't pass an address in the reserved
2157 // space here, lots of asserts fire.
2158
2159 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2160 _g1_reserved.start());
2161 // We'll re-use the same region whether the alloc region will
2162 // require BOT updates or not and, if it doesn't, then a non-young
2163 // region will complain that it cannot support allocations without
2164 // BOT updates. So we'll tag the dummy region as young to avoid that.
2165 dummy_region->set_young();
2166 // Make sure it's full.
2167 dummy_region->set_top(dummy_region->end());
2168 G1AllocRegion::setup(this, dummy_region);
2169
2170 init_mutator_alloc_region();
2171
2172 // Do create of the monitoring and management support so that
2173 // values in the heap have been properly initialized.
2174 _g1mm = new G1MonitoringSupport(this);
2175
2176 G1StringDedup::initialize();
2177
2178 return JNI_OK;
2179 }
2180
2181 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2182 return HeapRegion::max_region_size();
2183 }
2184
2185 void G1CollectedHeap::ref_processing_init() {
2186 // Reference processing in G1 currently works as follows:
2187 //
2188 // * There are two reference processor instances. One is
2189 // used to record and process discovered references
2190 // during concurrent marking; the other is used to
2191 // record and process references during STW pauses
2192 // (both full and incremental).
2193 // * Both ref processors need to 'span' the entire heap as
2194 // the regions in the collection set may be dotted around.
2195 //
2196 // * For the concurrent marking ref processor:
2197 // * Reference discovery is enabled at initial marking.
2198 // * Reference discovery is disabled and the discovered
2199 // references processed etc during remarking.
2200 // * Reference discovery is MT (see below).
2201 // * Reference discovery requires a barrier (see below).
2202 // * Reference processing may or may not be MT
2203 // (depending on the value of ParallelRefProcEnabled
2204 // and ParallelGCThreads).
2205 // * A full GC disables reference discovery by the CM
2206 // ref processor and abandons any entries on it's
2207 // discovered lists.
2208 //
2209 // * For the STW processor:
2210 // * Non MT discovery is enabled at the start of a full GC.
2211 // * Processing and enqueueing during a full GC is non-MT.
2212 // * During a full GC, references are processed after marking.
2213 //
2214 // * Discovery (may or may not be MT) is enabled at the start
2215 // of an incremental evacuation pause.
2216 // * References are processed near the end of a STW evacuation pause.
2217 // * For both types of GC:
2218 // * Discovery is atomic - i.e. not concurrent.
2219 // * Reference discovery will not need a barrier.
2220
2221 SharedHeap::ref_processing_init();
2222 MemRegion mr = reserved_region();
2223
2224 // Concurrent Mark ref processor
2225 _ref_processor_cm =
2226 new ReferenceProcessor(mr, // span
2227 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2228 // mt processing
2229 (int) ParallelGCThreads,
2230 // degree of mt processing
2231 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2232 // mt discovery
2233 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2234 // degree of mt discovery
2235 false,
2236 // Reference discovery is not atomic
2237 &_is_alive_closure_cm,
2238 // is alive closure
2239 // (for efficiency/performance)
2240 true);
2241 // Setting next fields of discovered
2242 // lists requires a barrier.
2243
2244 // STW ref processor
2245 _ref_processor_stw =
2246 new ReferenceProcessor(mr, // span
2247 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2248 // mt processing
2249 MAX2((int)ParallelGCThreads, 1),
2250 // degree of mt processing
2251 (ParallelGCThreads > 1),
2252 // mt discovery
2253 MAX2((int)ParallelGCThreads, 1),
2254 // degree of mt discovery
2255 true,
2256 // Reference discovery is atomic
2257 &_is_alive_closure_stw,
2258 // is alive closure
2259 // (for efficiency/performance)
2260 false);
2261 // Setting next fields of discovered
2262 // lists does not require a barrier.
2263 }
2264
2265 size_t G1CollectedHeap::capacity() const {
2266 return _g1_committed.byte_size();
2267 }
2268
2269 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2270 assert(!hr->continuesHumongous(), "pre-condition");
2271 hr->reset_gc_time_stamp();
2272 if (hr->startsHumongous()) {
2273 uint first_index = hr->hrs_index() + 1;
2274 uint last_index = hr->last_hc_index();
2275 for (uint i = first_index; i < last_index; i += 1) {
2276 HeapRegion* chr = region_at(i);
2277 assert(chr->continuesHumongous(), "sanity");
2278 chr->reset_gc_time_stamp();
2279 }
2280 }
2281 }
2282
2283 #ifndef PRODUCT
2284 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2285 private:
2286 unsigned _gc_time_stamp;
2287 bool _failures;
2288
2289 public:
2290 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2291 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2292
2293 virtual bool doHeapRegion(HeapRegion* hr) {
2294 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2295 if (_gc_time_stamp != region_gc_time_stamp) {
2296 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2297 "expected %d", HR_FORMAT_PARAMS(hr),
2298 region_gc_time_stamp, _gc_time_stamp);
2299 _failures = true;
2300 }
2301 return false;
2302 }
2303
2304 bool failures() { return _failures; }
2305 };
2306
2307 void G1CollectedHeap::check_gc_time_stamps() {
2308 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2309 heap_region_iterate(&cl);
2310 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2311 }
2312 #endif // PRODUCT
2313
2314 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2315 DirtyCardQueue* into_cset_dcq,
2316 bool concurrent,
2317 int worker_i) {
2318 // Clean cards in the hot card cache
2319 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2320 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2321
2322 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2323 int n_completed_buffers = 0;
2324 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2325 n_completed_buffers++;
2326 }
2327 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2328 dcqs.clear_n_completed_buffers();
2329 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2330 }
2331
2332
2333 // Computes the sum of the storage used by the various regions.
2334
2335 size_t G1CollectedHeap::used() const {
2336 assert(Heap_lock->owner() != NULL,
2337 "Should be owned on this thread's behalf.");
2338 size_t result = _summary_bytes_used;
2339 // Read only once in case it is set to NULL concurrently
2340 HeapRegion* hr = _mutator_alloc_region.get();
2341 if (hr != NULL)
2342 result += hr->used();
2343 return result;
2344 }
2345
2346 size_t G1CollectedHeap::used_unlocked() const {
2347 size_t result = _summary_bytes_used;
2348 return result;
2349 }
2350
2351 class SumUsedClosure: public HeapRegionClosure {
2352 size_t _used;
2353 public:
2354 SumUsedClosure() : _used(0) {}
2355 bool doHeapRegion(HeapRegion* r) {
2356 if (!r->continuesHumongous()) {
2357 _used += r->used();
2358 }
2359 return false;
2360 }
2361 size_t result() { return _used; }
2362 };
2363
2364 size_t G1CollectedHeap::recalculate_used() const {
2365 double recalculate_used_start = os::elapsedTime();
2366
2367 SumUsedClosure blk;
2368 heap_region_iterate(&blk);
2369
2370 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2371 return blk.result();
2372 }
2373
2374 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2375 switch (cause) {
2376 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2377 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2378 case GCCause::_g1_humongous_allocation: return true;
2379 default: return false;
2380 }
2381 }
2382
2383 #ifndef PRODUCT
2384 void G1CollectedHeap::allocate_dummy_regions() {
2385 // Let's fill up most of the region
2386 size_t word_size = HeapRegion::GrainWords - 1024;
2387 // And as a result the region we'll allocate will be humongous.
2388 guarantee(isHumongous(word_size), "sanity");
2389
2390 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2391 // Let's use the existing mechanism for the allocation
2392 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2393 if (dummy_obj != NULL) {
2394 MemRegion mr(dummy_obj, word_size);
2395 CollectedHeap::fill_with_object(mr);
2396 } else {
2397 // If we can't allocate once, we probably cannot allocate
2398 // again. Let's get out of the loop.
2399 break;
2400 }
2401 }
2402 }
2403 #endif // !PRODUCT
2404
2405 void G1CollectedHeap::increment_old_marking_cycles_started() {
2406 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2407 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2408 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2409 _old_marking_cycles_started, _old_marking_cycles_completed));
2410
2411 _old_marking_cycles_started++;
2412 }
2413
2414 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2415 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2416
2417 // We assume that if concurrent == true, then the caller is a
2418 // concurrent thread that was joined the Suspendible Thread
2419 // Set. If there's ever a cheap way to check this, we should add an
2420 // assert here.
2421
2422 // Given that this method is called at the end of a Full GC or of a
2423 // concurrent cycle, and those can be nested (i.e., a Full GC can
2424 // interrupt a concurrent cycle), the number of full collections
2425 // completed should be either one (in the case where there was no
2426 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2427 // behind the number of full collections started.
2428
2429 // This is the case for the inner caller, i.e. a Full GC.
2430 assert(concurrent ||
2431 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2432 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2433 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2434 "is inconsistent with _old_marking_cycles_completed = %u",
2435 _old_marking_cycles_started, _old_marking_cycles_completed));
2436
2437 // This is the case for the outer caller, i.e. the concurrent cycle.
2438 assert(!concurrent ||
2439 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2440 err_msg("for outer caller (concurrent cycle): "
2441 "_old_marking_cycles_started = %u "
2442 "is inconsistent with _old_marking_cycles_completed = %u",
2443 _old_marking_cycles_started, _old_marking_cycles_completed));
2444
2445 _old_marking_cycles_completed += 1;
2446
2447 // We need to clear the "in_progress" flag in the CM thread before
2448 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2449 // is set) so that if a waiter requests another System.gc() it doesn't
2450 // incorrectly see that a marking cycle is still in progress.
2451 if (concurrent) {
2452 _cmThread->clear_in_progress();
2453 }
2454
2455 // This notify_all() will ensure that a thread that called
2456 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2457 // and it's waiting for a full GC to finish will be woken up. It is
2458 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2459 FullGCCount_lock->notify_all();
2460 }
2461
2462 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2463 _concurrent_cycle_started = true;
2464 _gc_timer_cm->register_gc_start(start_time);
2465
2466 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2467 trace_heap_before_gc(_gc_tracer_cm);
2468 }
2469
2470 void G1CollectedHeap::register_concurrent_cycle_end() {
2471 if (_concurrent_cycle_started) {
2472 if (_cm->has_aborted()) {
2473 _gc_tracer_cm->report_concurrent_mode_failure();
2474 }
2475
2476 _gc_timer_cm->register_gc_end();
2477 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2478
2479 _concurrent_cycle_started = false;
2480 }
2481 }
2482
2483 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2484 if (_concurrent_cycle_started) {
2485 trace_heap_after_gc(_gc_tracer_cm);
2486 }
2487 }
2488
2489 G1YCType G1CollectedHeap::yc_type() {
2490 bool is_young = g1_policy()->gcs_are_young();
2491 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2492 bool is_during_mark = mark_in_progress();
2493
2494 if (is_initial_mark) {
2495 return InitialMark;
2496 } else if (is_during_mark) {
2497 return DuringMark;
2498 } else if (is_young) {
2499 return Normal;
2500 } else {
2501 return Mixed;
2502 }
2503 }
2504
2505 void G1CollectedHeap::collect(GCCause::Cause cause) {
2506 assert_heap_not_locked();
2507
2508 unsigned int gc_count_before;
2509 unsigned int old_marking_count_before;
2510 bool retry_gc;
2511
2512 do {
2513 retry_gc = false;
2514
2515 {
2516 MutexLocker ml(Heap_lock);
2517
2518 // Read the GC count while holding the Heap_lock
2519 gc_count_before = total_collections();
2520 old_marking_count_before = _old_marking_cycles_started;
2521 }
2522
2523 if (should_do_concurrent_full_gc(cause)) {
2524 // Schedule an initial-mark evacuation pause that will start a
2525 // concurrent cycle. We're setting word_size to 0 which means that
2526 // we are not requesting a post-GC allocation.
2527 VM_G1IncCollectionPause op(gc_count_before,
2528 0, /* word_size */
2529 true, /* should_initiate_conc_mark */
2530 g1_policy()->max_pause_time_ms(),
2531 cause);
2532
2533 VMThread::execute(&op);
2534 if (!op.pause_succeeded()) {
2535 if (old_marking_count_before == _old_marking_cycles_started) {
2536 retry_gc = op.should_retry_gc();
2537 } else {
2538 // A Full GC happened while we were trying to schedule the
2539 // initial-mark GC. No point in starting a new cycle given
2540 // that the whole heap was collected anyway.
2541 }
2542
2543 if (retry_gc) {
2544 if (GC_locker::is_active_and_needs_gc()) {
2545 GC_locker::stall_until_clear();
2546 }
2547 }
2548 }
2549 } else {
2550 if (cause == GCCause::_gc_locker
2551 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2552
2553 // Schedule a standard evacuation pause. We're setting word_size
2554 // to 0 which means that we are not requesting a post-GC allocation.
2555 VM_G1IncCollectionPause op(gc_count_before,
2556 0, /* word_size */
2557 false, /* should_initiate_conc_mark */
2558 g1_policy()->max_pause_time_ms(),
2559 cause);
2560 VMThread::execute(&op);
2561 } else {
2562 // Schedule a Full GC.
2563 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2564 VMThread::execute(&op);
2565 }
2566 }
2567 } while (retry_gc);
2568 }
2569
2570 bool G1CollectedHeap::is_in(const void* p) const {
2571 if (_g1_committed.contains(p)) {
2572 // Given that we know that p is in the committed space,
2573 // heap_region_containing_raw() should successfully
2574 // return the containing region.
2575 HeapRegion* hr = heap_region_containing_raw(p);
2576 return hr->is_in(p);
2577 } else {
2578 return false;
2579 }
2580 }
2581
2582 // Iteration functions.
2583
2584 // Iterates an OopClosure over all ref-containing fields of objects
2585 // within a HeapRegion.
2586
2587 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2588 MemRegion _mr;
2589 ExtendedOopClosure* _cl;
2590 public:
2591 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2592 : _mr(mr), _cl(cl) {}
2593 bool doHeapRegion(HeapRegion* r) {
2594 if (!r->continuesHumongous()) {
2595 r->oop_iterate(_cl);
2596 }
2597 return false;
2598 }
2599 };
2600
2601 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2602 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2603 heap_region_iterate(&blk);
2604 }
2605
2606 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2607 IterateOopClosureRegionClosure blk(mr, cl);
2608 heap_region_iterate(&blk);
2609 }
2610
2611 // Iterates an ObjectClosure over all objects within a HeapRegion.
2612
2613 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2614 ObjectClosure* _cl;
2615 public:
2616 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2617 bool doHeapRegion(HeapRegion* r) {
2618 if (! r->continuesHumongous()) {
2619 r->object_iterate(_cl);
2620 }
2621 return false;
2622 }
2623 };
2624
2625 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2626 IterateObjectClosureRegionClosure blk(cl);
2627 heap_region_iterate(&blk);
2628 }
2629
2630 // Calls a SpaceClosure on a HeapRegion.
2631
2632 class SpaceClosureRegionClosure: public HeapRegionClosure {
2633 SpaceClosure* _cl;
2634 public:
2635 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2636 bool doHeapRegion(HeapRegion* r) {
2637 _cl->do_space(r);
2638 return false;
2639 }
2640 };
2641
2642 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2643 SpaceClosureRegionClosure blk(cl);
2644 heap_region_iterate(&blk);
2645 }
2646
2647 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2648 _hrs.iterate(cl);
2649 }
2650
2651 void
2652 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2653 uint worker_id,
2654 uint no_of_par_workers,
2655 jint claim_value) {
2656 const uint regions = n_regions();
2657 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2658 no_of_par_workers :
2659 1);
2660 assert(UseDynamicNumberOfGCThreads ||
2661 no_of_par_workers == workers()->total_workers(),
2662 "Non dynamic should use fixed number of workers");
2663 // try to spread out the starting points of the workers
2664 const HeapRegion* start_hr =
2665 start_region_for_worker(worker_id, no_of_par_workers);
2666 const uint start_index = start_hr->hrs_index();
2667
2668 // each worker will actually look at all regions
2669 for (uint count = 0; count < regions; ++count) {
2670 const uint index = (start_index + count) % regions;
2671 assert(0 <= index && index < regions, "sanity");
2672 HeapRegion* r = region_at(index);
2673 // we'll ignore "continues humongous" regions (we'll process them
2674 // when we come across their corresponding "start humongous"
2675 // region) and regions already claimed
2676 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2677 continue;
2678 }
2679 // OK, try to claim it
2680 if (r->claimHeapRegion(claim_value)) {
2681 // success!
2682 assert(!r->continuesHumongous(), "sanity");
2683 if (r->startsHumongous()) {
2684 // If the region is "starts humongous" we'll iterate over its
2685 // "continues humongous" first; in fact we'll do them
2686 // first. The order is important. In on case, calling the
2687 // closure on the "starts humongous" region might de-allocate
2688 // and clear all its "continues humongous" regions and, as a
2689 // result, we might end up processing them twice. So, we'll do
2690 // them first (notice: most closures will ignore them anyway) and
2691 // then we'll do the "starts humongous" region.
2692 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2693 HeapRegion* chr = region_at(ch_index);
2694
2695 // if the region has already been claimed or it's not
2696 // "continues humongous" we're done
2697 if (chr->claim_value() == claim_value ||
2698 !chr->continuesHumongous()) {
2699 break;
2700 }
2701
2702 // No one should have claimed it directly. We can given
2703 // that we claimed its "starts humongous" region.
2704 assert(chr->claim_value() != claim_value, "sanity");
2705 assert(chr->humongous_start_region() == r, "sanity");
2706
2707 if (chr->claimHeapRegion(claim_value)) {
2708 // we should always be able to claim it; no one else should
2709 // be trying to claim this region
2710
2711 bool res2 = cl->doHeapRegion(chr);
2712 assert(!res2, "Should not abort");
2713
2714 // Right now, this holds (i.e., no closure that actually
2715 // does something with "continues humongous" regions
2716 // clears them). We might have to weaken it in the future,
2717 // but let's leave these two asserts here for extra safety.
2718 assert(chr->continuesHumongous(), "should still be the case");
2719 assert(chr->humongous_start_region() == r, "sanity");
2720 } else {
2721 guarantee(false, "we should not reach here");
2722 }
2723 }
2724 }
2725
2726 assert(!r->continuesHumongous(), "sanity");
2727 bool res = cl->doHeapRegion(r);
2728 assert(!res, "Should not abort");
2729 }
2730 }
2731 }
2732
2733 class ResetClaimValuesClosure: public HeapRegionClosure {
2734 public:
2735 bool doHeapRegion(HeapRegion* r) {
2736 r->set_claim_value(HeapRegion::InitialClaimValue);
2737 return false;
2738 }
2739 };
2740
2741 void G1CollectedHeap::reset_heap_region_claim_values() {
2742 ResetClaimValuesClosure blk;
2743 heap_region_iterate(&blk);
2744 }
2745
2746 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2747 ResetClaimValuesClosure blk;
2748 collection_set_iterate(&blk);
2749 }
2750
2751 #ifdef ASSERT
2752 // This checks whether all regions in the heap have the correct claim
2753 // value. I also piggy-backed on this a check to ensure that the
2754 // humongous_start_region() information on "continues humongous"
2755 // regions is correct.
2756
2757 class CheckClaimValuesClosure : public HeapRegionClosure {
2758 private:
2759 jint _claim_value;
2760 uint _failures;
2761 HeapRegion* _sh_region;
2762
2763 public:
2764 CheckClaimValuesClosure(jint claim_value) :
2765 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2766 bool doHeapRegion(HeapRegion* r) {
2767 if (r->claim_value() != _claim_value) {
2768 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2769 "claim value = %d, should be %d",
2770 HR_FORMAT_PARAMS(r),
2771 r->claim_value(), _claim_value);
2772 ++_failures;
2773 }
2774 if (!r->isHumongous()) {
2775 _sh_region = NULL;
2776 } else if (r->startsHumongous()) {
2777 _sh_region = r;
2778 } else if (r->continuesHumongous()) {
2779 if (r->humongous_start_region() != _sh_region) {
2780 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2781 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2782 HR_FORMAT_PARAMS(r),
2783 r->humongous_start_region(),
2784 _sh_region);
2785 ++_failures;
2786 }
2787 }
2788 return false;
2789 }
2790 uint failures() { return _failures; }
2791 };
2792
2793 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2794 CheckClaimValuesClosure cl(claim_value);
2795 heap_region_iterate(&cl);
2796 return cl.failures() == 0;
2797 }
2798
2799 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2800 private:
2801 jint _claim_value;
2802 uint _failures;
2803
2804 public:
2805 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2806 _claim_value(claim_value), _failures(0) { }
2807
2808 uint failures() { return _failures; }
2809
2810 bool doHeapRegion(HeapRegion* hr) {
2811 assert(hr->in_collection_set(), "how?");
2812 assert(!hr->isHumongous(), "H-region in CSet");
2813 if (hr->claim_value() != _claim_value) {
2814 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2815 "claim value = %d, should be %d",
2816 HR_FORMAT_PARAMS(hr),
2817 hr->claim_value(), _claim_value);
2818 _failures += 1;
2819 }
2820 return false;
2821 }
2822 };
2823
2824 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2825 CheckClaimValuesInCSetHRClosure cl(claim_value);
2826 collection_set_iterate(&cl);
2827 return cl.failures() == 0;
2828 }
2829 #endif // ASSERT
2830
2831 // Clear the cached CSet starting regions and (more importantly)
2832 // the time stamps. Called when we reset the GC time stamp.
2833 void G1CollectedHeap::clear_cset_start_regions() {
2834 assert(_worker_cset_start_region != NULL, "sanity");
2835 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2836
2837 int n_queues = MAX2((int)ParallelGCThreads, 1);
2838 for (int i = 0; i < n_queues; i++) {
2839 _worker_cset_start_region[i] = NULL;
2840 _worker_cset_start_region_time_stamp[i] = 0;
2841 }
2842 }
2843
2844 // Given the id of a worker, obtain or calculate a suitable
2845 // starting region for iterating over the current collection set.
2846 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2847 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2848
2849 HeapRegion* result = NULL;
2850 unsigned gc_time_stamp = get_gc_time_stamp();
2851
2852 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2853 // Cached starting region for current worker was set
2854 // during the current pause - so it's valid.
2855 // Note: the cached starting heap region may be NULL
2856 // (when the collection set is empty).
2857 result = _worker_cset_start_region[worker_i];
2858 assert(result == NULL || result->in_collection_set(), "sanity");
2859 return result;
2860 }
2861
2862 // The cached entry was not valid so let's calculate
2863 // a suitable starting heap region for this worker.
2864
2865 // We want the parallel threads to start their collection
2866 // set iteration at different collection set regions to
2867 // avoid contention.
2868 // If we have:
2869 // n collection set regions
2870 // p threads
2871 // Then thread t will start at region floor ((t * n) / p)
2872
2873 result = g1_policy()->collection_set();
2874 if (G1CollectedHeap::use_parallel_gc_threads()) {
2875 uint cs_size = g1_policy()->cset_region_length();
2876 uint active_workers = workers()->active_workers();
2877 assert(UseDynamicNumberOfGCThreads ||
2878 active_workers == workers()->total_workers(),
2879 "Unless dynamic should use total workers");
2880
2881 uint end_ind = (cs_size * worker_i) / active_workers;
2882 uint start_ind = 0;
2883
2884 if (worker_i > 0 &&
2885 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2886 // Previous workers starting region is valid
2887 // so let's iterate from there
2888 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2889 result = _worker_cset_start_region[worker_i - 1];
2890 }
2891
2892 for (uint i = start_ind; i < end_ind; i++) {
2893 result = result->next_in_collection_set();
2894 }
2895 }
2896
2897 // Note: the calculated starting heap region may be NULL
2898 // (when the collection set is empty).
2899 assert(result == NULL || result->in_collection_set(), "sanity");
2900 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2901 "should be updated only once per pause");
2902 _worker_cset_start_region[worker_i] = result;
2903 OrderAccess::storestore();
2904 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2905 return result;
2906 }
2907
2908 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2909 uint no_of_par_workers) {
2910 uint worker_num =
2911 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2912 assert(UseDynamicNumberOfGCThreads ||
2913 no_of_par_workers == workers()->total_workers(),
2914 "Non dynamic should use fixed number of workers");
2915 const uint start_index = n_regions() * worker_i / worker_num;
2916 return region_at(start_index);
2917 }
2918
2919 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2920 HeapRegion* r = g1_policy()->collection_set();
2921 while (r != NULL) {
2922 HeapRegion* next = r->next_in_collection_set();
2923 if (cl->doHeapRegion(r)) {
2924 cl->incomplete();
2925 return;
2926 }
2927 r = next;
2928 }
2929 }
2930
2931 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2932 HeapRegionClosure *cl) {
2933 if (r == NULL) {
2934 // The CSet is empty so there's nothing to do.
2935 return;
2936 }
2937
2938 assert(r->in_collection_set(),
2939 "Start region must be a member of the collection set.");
2940 HeapRegion* cur = r;
2941 while (cur != NULL) {
2942 HeapRegion* next = cur->next_in_collection_set();
2943 if (cl->doHeapRegion(cur) && false) {
2944 cl->incomplete();
2945 return;
2946 }
2947 cur = next;
2948 }
2949 cur = g1_policy()->collection_set();
2950 while (cur != r) {
2951 HeapRegion* next = cur->next_in_collection_set();
2952 if (cl->doHeapRegion(cur) && false) {
2953 cl->incomplete();
2954 return;
2955 }
2956 cur = next;
2957 }
2958 }
2959
2960 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2961 return n_regions() > 0 ? region_at(0) : NULL;
2962 }
2963
2964
2965 Space* G1CollectedHeap::space_containing(const void* addr) const {
2966 Space* res = heap_region_containing(addr);
2967 return res;
2968 }
2969
2970 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2971 Space* sp = space_containing(addr);
2972 if (sp != NULL) {
2973 return sp->block_start(addr);
2974 }
2975 return NULL;
2976 }
2977
2978 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2979 Space* sp = space_containing(addr);
2980 assert(sp != NULL, "block_size of address outside of heap");
2981 return sp->block_size(addr);
2982 }
2983
2984 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2985 Space* sp = space_containing(addr);
2986 return sp->block_is_obj(addr);
2987 }
2988
2989 bool G1CollectedHeap::supports_tlab_allocation() const {
2990 return true;
2991 }
2992
2993 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2994 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2995 }
2996
2997 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2998 return young_list()->eden_used_bytes();
2999 }
3000
3001 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3002 // must be smaller than the humongous object limit.
3003 size_t G1CollectedHeap::max_tlab_size() const {
3004 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3005 }
3006
3007 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3008 // Return the remaining space in the cur alloc region, but not less than
3009 // the min TLAB size.
3010
3011 // Also, this value can be at most the humongous object threshold,
3012 // since we can't allow tlabs to grow big enough to accommodate
3013 // humongous objects.
3014
3015 HeapRegion* hr = _mutator_alloc_region.get();
3016 size_t max_tlab = max_tlab_size() * wordSize;
3017 if (hr == NULL) {
3018 return max_tlab;
3019 } else {
3020 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3021 }
3022 }
3023
3024 size_t G1CollectedHeap::max_capacity() const {
3025 return _g1_reserved.byte_size();
3026 }
3027
3028 jlong G1CollectedHeap::millis_since_last_gc() {
3029 // assert(false, "NYI");
3030 return 0;
3031 }
3032
3033 void G1CollectedHeap::prepare_for_verify() {
3034 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3035 ensure_parsability(false);
3036 }
3037 g1_rem_set()->prepare_for_verify();
3038 }
3039
3040 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3041 VerifyOption vo) {
3042 switch (vo) {
3043 case VerifyOption_G1UsePrevMarking:
3044 return hr->obj_allocated_since_prev_marking(obj);
3045 case VerifyOption_G1UseNextMarking:
3046 return hr->obj_allocated_since_next_marking(obj);
3047 case VerifyOption_G1UseMarkWord:
3048 return false;
3049 default:
3050 ShouldNotReachHere();
3051 }
3052 return false; // keep some compilers happy
3053 }
3054
3055 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3056 switch (vo) {
3057 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3058 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3059 case VerifyOption_G1UseMarkWord: return NULL;
3060 default: ShouldNotReachHere();
3061 }
3062 return NULL; // keep some compilers happy
3063 }
3064
3065 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3066 switch (vo) {
3067 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3068 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3069 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3070 default: ShouldNotReachHere();
3071 }
3072 return false; // keep some compilers happy
3073 }
3074
3075 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3076 switch (vo) {
3077 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3078 case VerifyOption_G1UseNextMarking: return "NTAMS";
3079 case VerifyOption_G1UseMarkWord: return "NONE";
3080 default: ShouldNotReachHere();
3081 }
3082 return NULL; // keep some compilers happy
3083 }
3084
3085 class VerifyRootsClosure: public OopClosure {
3086 private:
3087 G1CollectedHeap* _g1h;
3088 VerifyOption _vo;
3089 bool _failures;
3090 public:
3091 // _vo == UsePrevMarking -> use "prev" marking information,
3092 // _vo == UseNextMarking -> use "next" marking information,
3093 // _vo == UseMarkWord -> use mark word from object header.
3094 VerifyRootsClosure(VerifyOption vo) :
3095 _g1h(G1CollectedHeap::heap()),
3096 _vo(vo),
3097 _failures(false) { }
3098
3099 bool failures() { return _failures; }
3100
3101 template <class T> void do_oop_nv(T* p) {
3102 T heap_oop = oopDesc::load_heap_oop(p);
3103 if (!oopDesc::is_null(heap_oop)) {
3104 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3105 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3106 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3107 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3108 if (_vo == VerifyOption_G1UseMarkWord) {
3109 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3110 }
3111 obj->print_on(gclog_or_tty);
3112 _failures = true;
3113 }
3114 }
3115 }
3116
3117 void do_oop(oop* p) { do_oop_nv(p); }
3118 void do_oop(narrowOop* p) { do_oop_nv(p); }
3119 };
3120
3121 class G1VerifyCodeRootOopClosure: public OopClosure {
3122 G1CollectedHeap* _g1h;
3123 OopClosure* _root_cl;
3124 nmethod* _nm;
3125 VerifyOption _vo;
3126 bool _failures;
3127
3128 template <class T> void do_oop_work(T* p) {
3129 // First verify that this root is live
3130 _root_cl->do_oop(p);
3131
3132 if (!G1VerifyHeapRegionCodeRoots) {
3133 // We're not verifying the code roots attached to heap region.
3134 return;
3135 }
3136
3137 // Don't check the code roots during marking verification in a full GC
3138 if (_vo == VerifyOption_G1UseMarkWord) {
3139 return;
3140 }
3141
3142 // Now verify that the current nmethod (which contains p) is
3143 // in the code root list of the heap region containing the
3144 // object referenced by p.
3145
3146 T heap_oop = oopDesc::load_heap_oop(p);
3147 if (!oopDesc::is_null(heap_oop)) {
3148 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3149
3150 // Now fetch the region containing the object
3151 HeapRegion* hr = _g1h->heap_region_containing(obj);
3152 HeapRegionRemSet* hrrs = hr->rem_set();
3153 // Verify that the strong code root list for this region
3154 // contains the nmethod
3155 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3156 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3157 "from nmethod "PTR_FORMAT" not in strong "
3158 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3159 p, _nm, hr->bottom(), hr->end());
3160 _failures = true;
3161 }
3162 }
3163 }
3164
3165 public:
3166 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3167 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3168
3169 void do_oop(oop* p) { do_oop_work(p); }
3170 void do_oop(narrowOop* p) { do_oop_work(p); }
3171
3172 void set_nmethod(nmethod* nm) { _nm = nm; }
3173 bool failures() { return _failures; }
3174 };
3175
3176 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3177 G1VerifyCodeRootOopClosure* _oop_cl;
3178
3179 public:
3180 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3181 _oop_cl(oop_cl) {}
3182
3183 void do_code_blob(CodeBlob* cb) {
3184 nmethod* nm = cb->as_nmethod_or_null();
3185 if (nm != NULL) {
3186 _oop_cl->set_nmethod(nm);
3187 nm->oops_do(_oop_cl);
3188 }
3189 }
3190 };
3191
3192 class YoungRefCounterClosure : public OopClosure {
3193 G1CollectedHeap* _g1h;
3194 int _count;
3195 public:
3196 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3197 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3198 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3199
3200 int count() { return _count; }
3201 void reset_count() { _count = 0; };
3202 };
3203
3204 class VerifyKlassClosure: public KlassClosure {
3205 YoungRefCounterClosure _young_ref_counter_closure;
3206 OopClosure *_oop_closure;
3207 public:
3208 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3209 void do_klass(Klass* k) {
3210 k->oops_do(_oop_closure);
3211
3212 _young_ref_counter_closure.reset_count();
3213 k->oops_do(&_young_ref_counter_closure);
3214 if (_young_ref_counter_closure.count() > 0) {
3215 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3216 }
3217 }
3218 };
3219
3220 class VerifyLivenessOopClosure: public OopClosure {
3221 G1CollectedHeap* _g1h;
3222 VerifyOption _vo;
3223 public:
3224 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3225 _g1h(g1h), _vo(vo)
3226 { }
3227 void do_oop(narrowOop *p) { do_oop_work(p); }
3228 void do_oop( oop *p) { do_oop_work(p); }
3229
3230 template <class T> void do_oop_work(T *p) {
3231 oop obj = oopDesc::load_decode_heap_oop(p);
3232 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3233 "Dead object referenced by a not dead object");
3234 }
3235 };
3236
3237 class VerifyObjsInRegionClosure: public ObjectClosure {
3238 private:
3239 G1CollectedHeap* _g1h;
3240 size_t _live_bytes;
3241 HeapRegion *_hr;
3242 VerifyOption _vo;
3243 public:
3244 // _vo == UsePrevMarking -> use "prev" marking information,
3245 // _vo == UseNextMarking -> use "next" marking information,
3246 // _vo == UseMarkWord -> use mark word from object header.
3247 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3248 : _live_bytes(0), _hr(hr), _vo(vo) {
3249 _g1h = G1CollectedHeap::heap();
3250 }
3251 void do_object(oop o) {
3252 VerifyLivenessOopClosure isLive(_g1h, _vo);
3253 assert(o != NULL, "Huh?");
3254 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3255 // If the object is alive according to the mark word,
3256 // then verify that the marking information agrees.
3257 // Note we can't verify the contra-positive of the
3258 // above: if the object is dead (according to the mark
3259 // word), it may not be marked, or may have been marked
3260 // but has since became dead, or may have been allocated
3261 // since the last marking.
3262 if (_vo == VerifyOption_G1UseMarkWord) {
3263 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3264 }
3265
3266 o->oop_iterate_no_header(&isLive);
3267 if (!_hr->obj_allocated_since_prev_marking(o)) {
3268 size_t obj_size = o->size(); // Make sure we don't overflow
3269 _live_bytes += (obj_size * HeapWordSize);
3270 }
3271 }
3272 }
3273 size_t live_bytes() { return _live_bytes; }
3274 };
3275
3276 class PrintObjsInRegionClosure : public ObjectClosure {
3277 HeapRegion *_hr;
3278 G1CollectedHeap *_g1;
3279 public:
3280 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3281 _g1 = G1CollectedHeap::heap();
3282 };
3283
3284 void do_object(oop o) {
3285 if (o != NULL) {
3286 HeapWord *start = (HeapWord *) o;
3287 size_t word_sz = o->size();
3288 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3289 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3290 (void*) o, word_sz,
3291 _g1->isMarkedPrev(o),
3292 _g1->isMarkedNext(o),
3293 _hr->obj_allocated_since_prev_marking(o));
3294 HeapWord *end = start + word_sz;
3295 HeapWord *cur;
3296 int *val;
3297 for (cur = start; cur < end; cur++) {
3298 val = (int *) cur;
3299 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3300 }
3301 }
3302 }
3303 };
3304
3305 class VerifyRegionClosure: public HeapRegionClosure {
3306 private:
3307 bool _par;
3308 VerifyOption _vo;
3309 bool _failures;
3310 public:
3311 // _vo == UsePrevMarking -> use "prev" marking information,
3312 // _vo == UseNextMarking -> use "next" marking information,
3313 // _vo == UseMarkWord -> use mark word from object header.
3314 VerifyRegionClosure(bool par, VerifyOption vo)
3315 : _par(par),
3316 _vo(vo),
3317 _failures(false) {}
3318
3319 bool failures() {
3320 return _failures;
3321 }
3322
3323 bool doHeapRegion(HeapRegion* r) {
3324 if (!r->continuesHumongous()) {
3325 bool failures = false;
3326 r->verify(_vo, &failures);
3327 if (failures) {
3328 _failures = true;
3329 } else {
3330 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3331 r->object_iterate(¬_dead_yet_cl);
3332 if (_vo != VerifyOption_G1UseNextMarking) {
3333 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3334 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3335 "max_live_bytes "SIZE_FORMAT" "
3336 "< calculated "SIZE_FORMAT,
3337 r->bottom(), r->end(),
3338 r->max_live_bytes(),
3339 not_dead_yet_cl.live_bytes());
3340 _failures = true;
3341 }
3342 } else {
3343 // When vo == UseNextMarking we cannot currently do a sanity
3344 // check on the live bytes as the calculation has not been
3345 // finalized yet.
3346 }
3347 }
3348 }
3349 return false; // stop the region iteration if we hit a failure
3350 }
3351 };
3352
3353 // This is the task used for parallel verification of the heap regions
3354
3355 class G1ParVerifyTask: public AbstractGangTask {
3356 private:
3357 G1CollectedHeap* _g1h;
3358 VerifyOption _vo;
3359 bool _failures;
3360
3361 public:
3362 // _vo == UsePrevMarking -> use "prev" marking information,
3363 // _vo == UseNextMarking -> use "next" marking information,
3364 // _vo == UseMarkWord -> use mark word from object header.
3365 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3366 AbstractGangTask("Parallel verify task"),
3367 _g1h(g1h),
3368 _vo(vo),
3369 _failures(false) { }
3370
3371 bool failures() {
3372 return _failures;
3373 }
3374
3375 void work(uint worker_id) {
3376 HandleMark hm;
3377 VerifyRegionClosure blk(true, _vo);
3378 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3379 _g1h->workers()->active_workers(),
3380 HeapRegion::ParVerifyClaimValue);
3381 if (blk.failures()) {
3382 _failures = true;
3383 }
3384 }
3385 };
3386
3387 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3388 if (SafepointSynchronize::is_at_safepoint()) {
3389 assert(Thread::current()->is_VM_thread(),
3390 "Expected to be executed serially by the VM thread at this point");
3391
3392 if (!silent) { gclog_or_tty->print("Roots "); }
3393 VerifyRootsClosure rootsCl(vo);
3394 VerifyKlassClosure klassCl(this, &rootsCl);
3395
3396 // We apply the relevant closures to all the oops in the
3397 // system dictionary, class loader data graph and the string table.
3398 // Don't verify the code cache here, since it's verified below.
3399 const int so = SO_AllClasses | SO_Strings;
3400
3401 // Need cleared claim bits for the strong roots processing
3402 ClassLoaderDataGraph::clear_claimed_marks();
3403
3404 process_strong_roots(true, // activate StrongRootsScope
3405 ScanningOption(so), // roots scanning options
3406 &rootsCl,
3407 &klassCl
3408 );
3409
3410 // Verify the nmethods in the code cache.
3411 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3412 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3413 CodeCache::blobs_do(&blobsCl);
3414
3415 bool failures = rootsCl.failures() || codeRootsCl.failures();
3416
3417 if (vo != VerifyOption_G1UseMarkWord) {
3418 // If we're verifying during a full GC then the region sets
3419 // will have been torn down at the start of the GC. Therefore
3420 // verifying the region sets will fail. So we only verify
3421 // the region sets when not in a full GC.
3422 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3423 verify_region_sets();
3424 }
3425
3426 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3427 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3428 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3429 "sanity check");
3430
3431 G1ParVerifyTask task(this, vo);
3432 assert(UseDynamicNumberOfGCThreads ||
3433 workers()->active_workers() == workers()->total_workers(),
3434 "If not dynamic should be using all the workers");
3435 int n_workers = workers()->active_workers();
3436 set_par_threads(n_workers);
3437 workers()->run_task(&task);
3438 set_par_threads(0);
3439 if (task.failures()) {
3440 failures = true;
3441 }
3442
3443 // Checks that the expected amount of parallel work was done.
3444 // The implication is that n_workers is > 0.
3445 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3446 "sanity check");
3447
3448 reset_heap_region_claim_values();
3449
3450 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3451 "sanity check");
3452 } else {
3453 VerifyRegionClosure blk(false, vo);
3454 heap_region_iterate(&blk);
3455 if (blk.failures()) {
3456 failures = true;
3457 }
3458 }
3459 if (!silent) gclog_or_tty->print("RemSet ");
3460 rem_set()->verify();
3461
3462 if (G1StringDedup::is_enabled()) {
3463 if (!silent) gclog_or_tty->print("StrDedup ");
3464 G1StringDedup::verify();
3465 }
3466
3467 if (failures) {
3468 gclog_or_tty->print_cr("Heap:");
3469 // It helps to have the per-region information in the output to
3470 // help us track down what went wrong. This is why we call
3471 // print_extended_on() instead of print_on().
3472 print_extended_on(gclog_or_tty);
3473 gclog_or_tty->print_cr("");
3474 #ifndef PRODUCT
3475 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3476 concurrent_mark()->print_reachable("at-verification-failure",
3477 vo, false /* all */);
3478 }
3479 #endif
3480 gclog_or_tty->flush();
3481 }
3482 guarantee(!failures, "there should not have been any failures");
3483 } else {
3484 if (!silent) {
3485 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3486 if (G1StringDedup::is_enabled()) {
3487 gclog_or_tty->print(", StrDedup");
3488 }
3489 gclog_or_tty->print(") ");
3490 }
3491 }
3492 }
3493
3494 void G1CollectedHeap::verify(bool silent) {
3495 verify(silent, VerifyOption_G1UsePrevMarking);
3496 }
3497
3498 double G1CollectedHeap::verify(bool guard, const char* msg) {
3499 double verify_time_ms = 0.0;
3500
3501 if (guard && total_collections() >= VerifyGCStartAt) {
3502 double verify_start = os::elapsedTime();
3503 HandleMark hm; // Discard invalid handles created during verification
3504 prepare_for_verify();
3505 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3506 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3507 }
3508
3509 return verify_time_ms;
3510 }
3511
3512 void G1CollectedHeap::verify_before_gc() {
3513 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3514 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3515 }
3516
3517 void G1CollectedHeap::verify_after_gc() {
3518 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3519 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3520 }
3521
3522 class PrintRegionClosure: public HeapRegionClosure {
3523 outputStream* _st;
3524 public:
3525 PrintRegionClosure(outputStream* st) : _st(st) {}
3526 bool doHeapRegion(HeapRegion* r) {
3527 r->print_on(_st);
3528 return false;
3529 }
3530 };
3531
3532 void G1CollectedHeap::print_on(outputStream* st) const {
3533 st->print(" %-20s", "garbage-first heap");
3534 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3535 capacity()/K, used_unlocked()/K);
3536 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3537 _g1_storage.low_boundary(),
3538 _g1_storage.high(),
3539 _g1_storage.high_boundary());
3540 st->cr();
3541 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3542 uint young_regions = _young_list->length();
3543 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3544 (size_t) young_regions * HeapRegion::GrainBytes / K);
3545 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3546 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3547 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3548 st->cr();
3549 MetaspaceAux::print_on(st);
3550 }
3551
3552 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3553 print_on(st);
3554
3555 // Print the per-region information.
3556 st->cr();
3557 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3558 "HS=humongous(starts), HC=humongous(continues), "
3559 "CS=collection set, F=free, TS=gc time stamp, "
3560 "PTAMS=previous top-at-mark-start, "
3561 "NTAMS=next top-at-mark-start)");
3562 PrintRegionClosure blk(st);
3563 heap_region_iterate(&blk);
3564 }
3565
3566 void G1CollectedHeap::print_on_error(outputStream* st) const {
3567 this->CollectedHeap::print_on_error(st);
3568
3569 if (_cm != NULL) {
3570 st->cr();
3571 _cm->print_on_error(st);
3572 }
3573 }
3574
3575 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3576 if (G1CollectedHeap::use_parallel_gc_threads()) {
3577 workers()->print_worker_threads_on(st);
3578 }
3579 _cmThread->print_on(st);
3580 st->cr();
3581 _cm->print_worker_threads_on(st);
3582 _cg1r->print_worker_threads_on(st);
3583 if (G1StringDedup::is_enabled()) {
3584 G1StringDedup::print_worker_threads_on(st);
3585 }
3586 }
3587
3588 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3589 if (G1CollectedHeap::use_parallel_gc_threads()) {
3590 workers()->threads_do(tc);
3591 }
3592 tc->do_thread(_cmThread);
3593 _cg1r->threads_do(tc);
3594 if (G1StringDedup::is_enabled()) {
3595 G1StringDedup::threads_do(tc);
3596 }
3597 }
3598
3599 void G1CollectedHeap::print_tracing_info() const {
3600 // We'll overload this to mean "trace GC pause statistics."
3601 if (TraceGen0Time || TraceGen1Time) {
3602 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3603 // to that.
3604 g1_policy()->print_tracing_info();
3605 }
3606 if (G1SummarizeRSetStats) {
3607 g1_rem_set()->print_summary_info();
3608 }
3609 if (G1SummarizeConcMark) {
3610 concurrent_mark()->print_summary_info();
3611 }
3612 g1_policy()->print_yg_surv_rate_info();
3613 SpecializationStats::print();
3614 }
3615
3616 #ifndef PRODUCT
3617 // Helpful for debugging RSet issues.
3618
3619 class PrintRSetsClosure : public HeapRegionClosure {
3620 private:
3621 const char* _msg;
3622 size_t _occupied_sum;
3623
3624 public:
3625 bool doHeapRegion(HeapRegion* r) {
3626 HeapRegionRemSet* hrrs = r->rem_set();
3627 size_t occupied = hrrs->occupied();
3628 _occupied_sum += occupied;
3629
3630 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3631 HR_FORMAT_PARAMS(r));
3632 if (occupied == 0) {
3633 gclog_or_tty->print_cr(" RSet is empty");
3634 } else {
3635 hrrs->print();
3636 }
3637 gclog_or_tty->print_cr("----------");
3638 return false;
3639 }
3640
3641 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3642 gclog_or_tty->cr();
3643 gclog_or_tty->print_cr("========================================");
3644 gclog_or_tty->print_cr(msg);
3645 gclog_or_tty->cr();
3646 }
3647
3648 ~PrintRSetsClosure() {
3649 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3650 gclog_or_tty->print_cr("========================================");
3651 gclog_or_tty->cr();
3652 }
3653 };
3654
3655 void G1CollectedHeap::print_cset_rsets() {
3656 PrintRSetsClosure cl("Printing CSet RSets");
3657 collection_set_iterate(&cl);
3658 }
3659
3660 void G1CollectedHeap::print_all_rsets() {
3661 PrintRSetsClosure cl("Printing All RSets");;
3662 heap_region_iterate(&cl);
3663 }
3664 #endif // PRODUCT
3665
3666 G1CollectedHeap* G1CollectedHeap::heap() {
3667 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3668 "not a garbage-first heap");
3669 return _g1h;
3670 }
3671
3672 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3673 // always_do_update_barrier = false;
3674 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3675 // Fill TLAB's and such
3676 accumulate_statistics_all_tlabs();
3677 ensure_parsability(true);
3678
3679 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3680 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3681 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3682 }
3683 }
3684
3685 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3686
3687 if (G1SummarizeRSetStats &&
3688 (G1SummarizeRSetStatsPeriod > 0) &&
3689 // we are at the end of the GC. Total collections has already been increased.
3690 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3691 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3692 }
3693
3694 // FIXME: what is this about?
3695 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3696 // is set.
3697 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3698 "derived pointer present"));
3699 // always_do_update_barrier = true;
3700
3701 resize_all_tlabs();
3702
3703 // We have just completed a GC. Update the soft reference
3704 // policy with the new heap occupancy
3705 Universe::update_heap_info_at_gc();
3706 }
3707
3708 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3709 unsigned int gc_count_before,
3710 bool* succeeded,
3711 GCCause::Cause gc_cause) {
3712 assert_heap_not_locked_and_not_at_safepoint();
3713 g1_policy()->record_stop_world_start();
3714 VM_G1IncCollectionPause op(gc_count_before,
3715 word_size,
3716 false, /* should_initiate_conc_mark */
3717 g1_policy()->max_pause_time_ms(),
3718 gc_cause);
3719 VMThread::execute(&op);
3720
3721 HeapWord* result = op.result();
3722 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3723 assert(result == NULL || ret_succeeded,
3724 "the result should be NULL if the VM did not succeed");
3725 *succeeded = ret_succeeded;
3726
3727 assert_heap_not_locked();
3728 return result;
3729 }
3730
3731 void
3732 G1CollectedHeap::doConcurrentMark() {
3733 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3734 if (!_cmThread->in_progress()) {
3735 _cmThread->set_started();
3736 CGC_lock->notify();
3737 }
3738 }
3739
3740 size_t G1CollectedHeap::pending_card_num() {
3741 size_t extra_cards = 0;
3742 JavaThread *curr = Threads::first();
3743 while (curr != NULL) {
3744 DirtyCardQueue& dcq = curr->dirty_card_queue();
3745 extra_cards += dcq.size();
3746 curr = curr->next();
3747 }
3748 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3749 size_t buffer_size = dcqs.buffer_size();
3750 size_t buffer_num = dcqs.completed_buffers_num();
3751
3752 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3753 // in bytes - not the number of 'entries'. We need to convert
3754 // into a number of cards.
3755 return (buffer_size * buffer_num + extra_cards) / oopSize;
3756 }
3757
3758 size_t G1CollectedHeap::cards_scanned() {
3759 return g1_rem_set()->cardsScanned();
3760 }
3761
3762 void
3763 G1CollectedHeap::setup_surviving_young_words() {
3764 assert(_surviving_young_words == NULL, "pre-condition");
3765 uint array_length = g1_policy()->young_cset_region_length();
3766 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3767 if (_surviving_young_words == NULL) {
3768 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3769 "Not enough space for young surv words summary.");
3770 }
3771 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3772 #ifdef ASSERT
3773 for (uint i = 0; i < array_length; ++i) {
3774 assert( _surviving_young_words[i] == 0, "memset above" );
3775 }
3776 #endif // !ASSERT
3777 }
3778
3779 void
3780 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3781 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3782 uint array_length = g1_policy()->young_cset_region_length();
3783 for (uint i = 0; i < array_length; ++i) {
3784 _surviving_young_words[i] += surv_young_words[i];
3785 }
3786 }
3787
3788 void
3789 G1CollectedHeap::cleanup_surviving_young_words() {
3790 guarantee( _surviving_young_words != NULL, "pre-condition" );
3791 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3792 _surviving_young_words = NULL;
3793 }
3794
3795 #ifdef ASSERT
3796 class VerifyCSetClosure: public HeapRegionClosure {
3797 public:
3798 bool doHeapRegion(HeapRegion* hr) {
3799 // Here we check that the CSet region's RSet is ready for parallel
3800 // iteration. The fields that we'll verify are only manipulated
3801 // when the region is part of a CSet and is collected. Afterwards,
3802 // we reset these fields when we clear the region's RSet (when the
3803 // region is freed) so they are ready when the region is
3804 // re-allocated. The only exception to this is if there's an
3805 // evacuation failure and instead of freeing the region we leave
3806 // it in the heap. In that case, we reset these fields during
3807 // evacuation failure handling.
3808 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3809
3810 // Here's a good place to add any other checks we'd like to
3811 // perform on CSet regions.
3812 return false;
3813 }
3814 };
3815 #endif // ASSERT
3816
3817 #if TASKQUEUE_STATS
3818 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3819 st->print_raw_cr("GC Task Stats");
3820 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3821 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3822 }
3823
3824 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3825 print_taskqueue_stats_hdr(st);
3826
3827 TaskQueueStats totals;
3828 const int n = workers() != NULL ? workers()->total_workers() : 1;
3829 for (int i = 0; i < n; ++i) {
3830 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3831 totals += task_queue(i)->stats;
3832 }
3833 st->print_raw("tot "); totals.print(st); st->cr();
3834
3835 DEBUG_ONLY(totals.verify());
3836 }
3837
3838 void G1CollectedHeap::reset_taskqueue_stats() {
3839 const int n = workers() != NULL ? workers()->total_workers() : 1;
3840 for (int i = 0; i < n; ++i) {
3841 task_queue(i)->stats.reset();
3842 }
3843 }
3844 #endif // TASKQUEUE_STATS
3845
3846 void G1CollectedHeap::log_gc_header() {
3847 if (!G1Log::fine()) {
3848 return;
3849 }
3850
3851 gclog_or_tty->date_stamp(PrintGCDateStamps);
3852 gclog_or_tty->stamp(PrintGCTimeStamps);
3853
3854 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3855 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3856 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3857
3858 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3859 }
3860
3861 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3862 if (!G1Log::fine()) {
3863 return;
3864 }
3865
3866 if (G1Log::finer()) {
3867 if (evacuation_failed()) {
3868 gclog_or_tty->print(" (to-space exhausted)");
3869 }
3870 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3871 g1_policy()->phase_times()->note_gc_end();
3872 g1_policy()->phase_times()->print(pause_time_sec);
3873 g1_policy()->print_detailed_heap_transition();
3874 } else {
3875 if (evacuation_failed()) {
3876 gclog_or_tty->print("--");
3877 }
3878 g1_policy()->print_heap_transition();
3879 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3880 }
3881 gclog_or_tty->flush();
3882 }
3883
3884 bool
3885 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3886 assert_at_safepoint(true /* should_be_vm_thread */);
3887 guarantee(!is_gc_active(), "collection is not reentrant");
3888
3889 if (GC_locker::check_active_before_gc()) {
3890 return false;
3891 }
3892
3893 _gc_timer_stw->register_gc_start();
3894
3895 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3896
3897 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3898 ResourceMark rm;
3899
3900 print_heap_before_gc();
3901 trace_heap_before_gc(_gc_tracer_stw);
3902
3903 verify_region_sets_optional();
3904 verify_dirty_young_regions();
3905
3906 // This call will decide whether this pause is an initial-mark
3907 // pause. If it is, during_initial_mark_pause() will return true
3908 // for the duration of this pause.
3909 g1_policy()->decide_on_conc_mark_initiation();
3910
3911 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3912 assert(!g1_policy()->during_initial_mark_pause() ||
3913 g1_policy()->gcs_are_young(), "sanity");
3914
3915 // We also do not allow mixed GCs during marking.
3916 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3917
3918 // Record whether this pause is an initial mark. When the current
3919 // thread has completed its logging output and it's safe to signal
3920 // the CM thread, the flag's value in the policy has been reset.
3921 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3922
3923 // Inner scope for scope based logging, timers, and stats collection
3924 {
3925 EvacuationInfo evacuation_info;
3926
3927 if (g1_policy()->during_initial_mark_pause()) {
3928 // We are about to start a marking cycle, so we increment the
3929 // full collection counter.
3930 increment_old_marking_cycles_started();
3931 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3932 }
3933
3934 _gc_tracer_stw->report_yc_type(yc_type());
3935
3936 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3937
3938 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3939 workers()->active_workers() : 1);
3940 double pause_start_sec = os::elapsedTime();
3941 g1_policy()->phase_times()->note_gc_start(active_workers);
3942 log_gc_header();
3943
3944 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3945 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3946
3947 // If the secondary_free_list is not empty, append it to the
3948 // free_list. No need to wait for the cleanup operation to finish;
3949 // the region allocation code will check the secondary_free_list
3950 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3951 // set, skip this step so that the region allocation code has to
3952 // get entries from the secondary_free_list.
3953 if (!G1StressConcRegionFreeing) {
3954 append_secondary_free_list_if_not_empty_with_lock();
3955 }
3956
3957 assert(check_young_list_well_formed(), "young list should be well formed");
3958 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3959 "sanity check");
3960
3961 // Don't dynamically change the number of GC threads this early. A value of
3962 // 0 is used to indicate serial work. When parallel work is done,
3963 // it will be set.
3964
3965 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3966 IsGCActiveMark x;
3967
3968 gc_prologue(false);
3969 increment_total_collections(false /* full gc */);
3970 increment_gc_time_stamp();
3971
3972 verify_before_gc();
3973
3974 COMPILER2_PRESENT(DerivedPointerTable::clear());
3975
3976 // Please see comment in g1CollectedHeap.hpp and
3977 // G1CollectedHeap::ref_processing_init() to see how
3978 // reference processing currently works in G1.
3979
3980 // Enable discovery in the STW reference processor
3981 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3982 true /*verify_no_refs*/);
3983
3984 {
3985 // We want to temporarily turn off discovery by the
3986 // CM ref processor, if necessary, and turn it back on
3987 // on again later if we do. Using a scoped
3988 // NoRefDiscovery object will do this.
3989 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3990
3991 // Forget the current alloc region (we might even choose it to be part
3992 // of the collection set!).
3993 release_mutator_alloc_region();
3994
3995 // We should call this after we retire the mutator alloc
3996 // region(s) so that all the ALLOC / RETIRE events are generated
3997 // before the start GC event.
3998 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3999
4000 // This timing is only used by the ergonomics to handle our pause target.
4001 // It is unclear why this should not include the full pause. We will
4002 // investigate this in CR 7178365.
4003 //
4004 // Preserving the old comment here if that helps the investigation:
4005 //
4006 // The elapsed time induced by the start time below deliberately elides
4007 // the possible verification above.
4008 double sample_start_time_sec = os::elapsedTime();
4009
4010 #if YOUNG_LIST_VERBOSE
4011 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4012 _young_list->print();
4013 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4014 #endif // YOUNG_LIST_VERBOSE
4015
4016 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4017
4018 double scan_wait_start = os::elapsedTime();
4019 // We have to wait until the CM threads finish scanning the
4020 // root regions as it's the only way to ensure that all the
4021 // objects on them have been correctly scanned before we start
4022 // moving them during the GC.
4023 bool waited = _cm->root_regions()->wait_until_scan_finished();
4024 double wait_time_ms = 0.0;
4025 if (waited) {
4026 double scan_wait_end = os::elapsedTime();
4027 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4028 }
4029 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4030
4031 #if YOUNG_LIST_VERBOSE
4032 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4033 _young_list->print();
4034 #endif // YOUNG_LIST_VERBOSE
4035
4036 if (g1_policy()->during_initial_mark_pause()) {
4037 concurrent_mark()->checkpointRootsInitialPre();
4038 }
4039
4040 #if YOUNG_LIST_VERBOSE
4041 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4042 _young_list->print();
4043 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4044 #endif // YOUNG_LIST_VERBOSE
4045
4046 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4047
4048 _cm->note_start_of_gc();
4049 // We should not verify the per-thread SATB buffers given that
4050 // we have not filtered them yet (we'll do so during the
4051 // GC). We also call this after finalize_cset() to
4052 // ensure that the CSet has been finalized.
4053 _cm->verify_no_cset_oops(true /* verify_stacks */,
4054 true /* verify_enqueued_buffers */,
4055 false /* verify_thread_buffers */,
4056 true /* verify_fingers */);
4057
4058 if (_hr_printer.is_active()) {
4059 HeapRegion* hr = g1_policy()->collection_set();
4060 while (hr != NULL) {
4061 G1HRPrinter::RegionType type;
4062 if (!hr->is_young()) {
4063 type = G1HRPrinter::Old;
4064 } else if (hr->is_survivor()) {
4065 type = G1HRPrinter::Survivor;
4066 } else {
4067 type = G1HRPrinter::Eden;
4068 }
4069 _hr_printer.cset(hr);
4070 hr = hr->next_in_collection_set();
4071 }
4072 }
4073
4074 #ifdef ASSERT
4075 VerifyCSetClosure cl;
4076 collection_set_iterate(&cl);
4077 #endif // ASSERT
4078
4079 setup_surviving_young_words();
4080
4081 // Initialize the GC alloc regions.
4082 init_gc_alloc_regions(evacuation_info);
4083
4084 // Actually do the work...
4085 evacuate_collection_set(evacuation_info);
4086
4087 // We do this to mainly verify the per-thread SATB buffers
4088 // (which have been filtered by now) since we didn't verify
4089 // them earlier. No point in re-checking the stacks / enqueued
4090 // buffers given that the CSet has not changed since last time
4091 // we checked.
4092 _cm->verify_no_cset_oops(false /* verify_stacks */,
4093 false /* verify_enqueued_buffers */,
4094 true /* verify_thread_buffers */,
4095 true /* verify_fingers */);
4096
4097 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4098 g1_policy()->clear_collection_set();
4099
4100 cleanup_surviving_young_words();
4101
4102 // Start a new incremental collection set for the next pause.
4103 g1_policy()->start_incremental_cset_building();
4104
4105 // Clear the _cset_fast_test bitmap in anticipation of adding
4106 // regions to the incremental collection set for the next
4107 // evacuation pause.
4108 clear_cset_fast_test();
4109
4110 _young_list->reset_sampled_info();
4111
4112 // Don't check the whole heap at this point as the
4113 // GC alloc regions from this pause have been tagged
4114 // as survivors and moved on to the survivor list.
4115 // Survivor regions will fail the !is_young() check.
4116 assert(check_young_list_empty(false /* check_heap */),
4117 "young list should be empty");
4118
4119 #if YOUNG_LIST_VERBOSE
4120 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4121 _young_list->print();
4122 #endif // YOUNG_LIST_VERBOSE
4123
4124 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4125 _young_list->first_survivor_region(),
4126 _young_list->last_survivor_region());
4127
4128 _young_list->reset_auxilary_lists();
4129
4130 if (evacuation_failed()) {
4131 _summary_bytes_used = recalculate_used();
4132 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4133 for (uint i = 0; i < n_queues; i++) {
4134 if (_evacuation_failed_info_array[i].has_failed()) {
4135 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4136 }
4137 }
4138 } else {
4139 // The "used" of the the collection set have already been subtracted
4140 // when they were freed. Add in the bytes evacuated.
4141 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4142 }
4143
4144 if (g1_policy()->during_initial_mark_pause()) {
4145 // We have to do this before we notify the CM threads that
4146 // they can start working to make sure that all the
4147 // appropriate initialization is done on the CM object.
4148 concurrent_mark()->checkpointRootsInitialPost();
4149 set_marking_started();
4150 // Note that we don't actually trigger the CM thread at
4151 // this point. We do that later when we're sure that
4152 // the current thread has completed its logging output.
4153 }
4154
4155 allocate_dummy_regions();
4156
4157 #if YOUNG_LIST_VERBOSE
4158 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4159 _young_list->print();
4160 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4161 #endif // YOUNG_LIST_VERBOSE
4162
4163 init_mutator_alloc_region();
4164
4165 {
4166 size_t expand_bytes = g1_policy()->expansion_amount();
4167 if (expand_bytes > 0) {
4168 size_t bytes_before = capacity();
4169 // No need for an ergo verbose message here,
4170 // expansion_amount() does this when it returns a value > 0.
4171 if (!expand(expand_bytes)) {
4172 // We failed to expand the heap so let's verify that
4173 // committed/uncommitted amount match the backing store
4174 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4175 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4176 }
4177 }
4178 }
4179
4180 // We redo the verification but now wrt to the new CSet which
4181 // has just got initialized after the previous CSet was freed.
4182 _cm->verify_no_cset_oops(true /* verify_stacks */,
4183 true /* verify_enqueued_buffers */,
4184 true /* verify_thread_buffers */,
4185 true /* verify_fingers */);
4186 _cm->note_end_of_gc();
4187
4188 // This timing is only used by the ergonomics to handle our pause target.
4189 // It is unclear why this should not include the full pause. We will
4190 // investigate this in CR 7178365.
4191 double sample_end_time_sec = os::elapsedTime();
4192 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4193 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4194
4195 MemoryService::track_memory_usage();
4196
4197 // In prepare_for_verify() below we'll need to scan the deferred
4198 // update buffers to bring the RSets up-to-date if
4199 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4200 // the update buffers we'll probably need to scan cards on the
4201 // regions we just allocated to (i.e., the GC alloc
4202 // regions). However, during the last GC we called
4203 // set_saved_mark() on all the GC alloc regions, so card
4204 // scanning might skip the [saved_mark_word()...top()] area of
4205 // those regions (i.e., the area we allocated objects into
4206 // during the last GC). But it shouldn't. Given that
4207 // saved_mark_word() is conditional on whether the GC time stamp
4208 // on the region is current or not, by incrementing the GC time
4209 // stamp here we invalidate all the GC time stamps on all the
4210 // regions and saved_mark_word() will simply return top() for
4211 // all the regions. This is a nicer way of ensuring this rather
4212 // than iterating over the regions and fixing them. In fact, the
4213 // GC time stamp increment here also ensures that
4214 // saved_mark_word() will return top() between pauses, i.e.,
4215 // during concurrent refinement. So we don't need the
4216 // is_gc_active() check to decided which top to use when
4217 // scanning cards (see CR 7039627).
4218 increment_gc_time_stamp();
4219
4220 verify_after_gc();
4221
4222 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4223 ref_processor_stw()->verify_no_references_recorded();
4224
4225 // CM reference discovery will be re-enabled if necessary.
4226 }
4227
4228 // We should do this after we potentially expand the heap so
4229 // that all the COMMIT events are generated before the end GC
4230 // event, and after we retire the GC alloc regions so that all
4231 // RETIRE events are generated before the end GC event.
4232 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4233
4234 if (mark_in_progress()) {
4235 concurrent_mark()->update_g1_committed();
4236 }
4237
4238 #ifdef TRACESPINNING
4239 ParallelTaskTerminator::print_termination_counts();
4240 #endif
4241
4242 gc_epilogue(false);
4243 }
4244
4245 // Print the remainder of the GC log output.
4246 log_gc_footer(os::elapsedTime() - pause_start_sec);
4247
4248 // It is not yet to safe to tell the concurrent mark to
4249 // start as we have some optional output below. We don't want the
4250 // output from the concurrent mark thread interfering with this
4251 // logging output either.
4252
4253 _hrs.verify_optional();
4254 verify_region_sets_optional();
4255
4256 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4257 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4258
4259 print_heap_after_gc();
4260 trace_heap_after_gc(_gc_tracer_stw);
4261
4262 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4263 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4264 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4265 // before any GC notifications are raised.
4266 g1mm()->update_sizes();
4267
4268 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4269 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4270 _gc_timer_stw->register_gc_end();
4271 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4272 }
4273 // It should now be safe to tell the concurrent mark thread to start
4274 // without its logging output interfering with the logging output
4275 // that came from the pause.
4276
4277 if (should_start_conc_mark) {
4278 // CAUTION: after the doConcurrentMark() call below,
4279 // the concurrent marking thread(s) could be running
4280 // concurrently with us. Make sure that anything after
4281 // this point does not assume that we are the only GC thread
4282 // running. Note: of course, the actual marking work will
4283 // not start until the safepoint itself is released in
4284 // ConcurrentGCThread::safepoint_desynchronize().
4285 doConcurrentMark();
4286 }
4287
4288 return true;
4289 }
4290
4291 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4292 {
4293 size_t gclab_word_size;
4294 switch (purpose) {
4295 case GCAllocForSurvived:
4296 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4297 break;
4298 case GCAllocForTenured:
4299 gclab_word_size = _old_plab_stats.desired_plab_sz();
4300 break;
4301 default:
4302 assert(false, "unknown GCAllocPurpose");
4303 gclab_word_size = _old_plab_stats.desired_plab_sz();
4304 break;
4305 }
4306
4307 // Prevent humongous PLAB sizes for two reasons:
4308 // * PLABs are allocated using a similar paths as oops, but should
4309 // never be in a humongous region
4310 // * Allowing humongous PLABs needlessly churns the region free lists
4311 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4312 }
4313
4314 void G1CollectedHeap::init_mutator_alloc_region() {
4315 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4316 _mutator_alloc_region.init();
4317 }
4318
4319 void G1CollectedHeap::release_mutator_alloc_region() {
4320 _mutator_alloc_region.release();
4321 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4322 }
4323
4324 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4325 assert_at_safepoint(true /* should_be_vm_thread */);
4326
4327 _survivor_gc_alloc_region.init();
4328 _old_gc_alloc_region.init();
4329 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4330 _retained_old_gc_alloc_region = NULL;
4331
4332 // We will discard the current GC alloc region if:
4333 // a) it's in the collection set (it can happen!),
4334 // b) it's already full (no point in using it),
4335 // c) it's empty (this means that it was emptied during
4336 // a cleanup and it should be on the free list now), or
4337 // d) it's humongous (this means that it was emptied
4338 // during a cleanup and was added to the free list, but
4339 // has been subsequently used to allocate a humongous
4340 // object that may be less than the region size).
4341 if (retained_region != NULL &&
4342 !retained_region->in_collection_set() &&
4343 !(retained_region->top() == retained_region->end()) &&
4344 !retained_region->is_empty() &&
4345 !retained_region->isHumongous()) {
4346 retained_region->set_saved_mark();
4347 // The retained region was added to the old region set when it was
4348 // retired. We have to remove it now, since we don't allow regions
4349 // we allocate to in the region sets. We'll re-add it later, when
4350 // it's retired again.
4351 _old_set.remove(retained_region);
4352 bool during_im = g1_policy()->during_initial_mark_pause();
4353 retained_region->note_start_of_copying(during_im);
4354 _old_gc_alloc_region.set(retained_region);
4355 _hr_printer.reuse(retained_region);
4356 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4357 }
4358 }
4359
4360 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4361 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4362 _old_gc_alloc_region.count());
4363 _survivor_gc_alloc_region.release();
4364 // If we have an old GC alloc region to release, we'll save it in
4365 // _retained_old_gc_alloc_region. If we don't
4366 // _retained_old_gc_alloc_region will become NULL. This is what we
4367 // want either way so no reason to check explicitly for either
4368 // condition.
4369 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4370
4371 if (ResizePLAB) {
4372 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4373 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4374 }
4375 }
4376
4377 void G1CollectedHeap::abandon_gc_alloc_regions() {
4378 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4379 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4380 _retained_old_gc_alloc_region = NULL;
4381 }
4382
4383 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4384 _drain_in_progress = false;
4385 set_evac_failure_closure(cl);
4386 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4387 }
4388
4389 void G1CollectedHeap::finalize_for_evac_failure() {
4390 assert(_evac_failure_scan_stack != NULL &&
4391 _evac_failure_scan_stack->length() == 0,
4392 "Postcondition");
4393 assert(!_drain_in_progress, "Postcondition");
4394 delete _evac_failure_scan_stack;
4395 _evac_failure_scan_stack = NULL;
4396 }
4397
4398 void G1CollectedHeap::remove_self_forwarding_pointers() {
4399 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4400
4401 double remove_self_forwards_start = os::elapsedTime();
4402
4403 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4404
4405 if (G1CollectedHeap::use_parallel_gc_threads()) {
4406 set_par_threads();
4407 workers()->run_task(&rsfp_task);
4408 set_par_threads(0);
4409 } else {
4410 rsfp_task.work(0);
4411 }
4412
4413 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4414
4415 // Reset the claim values in the regions in the collection set.
4416 reset_cset_heap_region_claim_values();
4417
4418 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4419
4420 // Now restore saved marks, if any.
4421 assert(_objs_with_preserved_marks.size() ==
4422 _preserved_marks_of_objs.size(), "Both or none.");
4423 while (!_objs_with_preserved_marks.is_empty()) {
4424 oop obj = _objs_with_preserved_marks.pop();
4425 markOop m = _preserved_marks_of_objs.pop();
4426 obj->set_mark(m);
4427 }
4428 _objs_with_preserved_marks.clear(true);
4429 _preserved_marks_of_objs.clear(true);
4430
4431 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4432 }
4433
4434 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4435 _evac_failure_scan_stack->push(obj);
4436 }
4437
4438 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4439 assert(_evac_failure_scan_stack != NULL, "precondition");
4440
4441 while (_evac_failure_scan_stack->length() > 0) {
4442 oop obj = _evac_failure_scan_stack->pop();
4443 _evac_failure_closure->set_region(heap_region_containing(obj));
4444 obj->oop_iterate_backwards(_evac_failure_closure);
4445 }
4446 }
4447
4448 oop
4449 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4450 oop old) {
4451 assert(obj_in_cs(old),
4452 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4453 (HeapWord*) old));
4454 markOop m = old->mark();
4455 oop forward_ptr = old->forward_to_atomic(old);
4456 if (forward_ptr == NULL) {
4457 // Forward-to-self succeeded.
4458 assert(_par_scan_state != NULL, "par scan state");
4459 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4460 uint queue_num = _par_scan_state->queue_num();
4461
4462 _evacuation_failed = true;
4463 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4464 if (_evac_failure_closure != cl) {
4465 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4466 assert(!_drain_in_progress,
4467 "Should only be true while someone holds the lock.");
4468 // Set the global evac-failure closure to the current thread's.
4469 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4470 set_evac_failure_closure(cl);
4471 // Now do the common part.
4472 handle_evacuation_failure_common(old, m);
4473 // Reset to NULL.
4474 set_evac_failure_closure(NULL);
4475 } else {
4476 // The lock is already held, and this is recursive.
4477 assert(_drain_in_progress, "This should only be the recursive case.");
4478 handle_evacuation_failure_common(old, m);
4479 }
4480 return old;
4481 } else {
4482 // Forward-to-self failed. Either someone else managed to allocate
4483 // space for this object (old != forward_ptr) or they beat us in
4484 // self-forwarding it (old == forward_ptr).
4485 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4486 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4487 "should not be in the CSet",
4488 (HeapWord*) old, (HeapWord*) forward_ptr));
4489 return forward_ptr;
4490 }
4491 }
4492
4493 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4494 preserve_mark_if_necessary(old, m);
4495
4496 HeapRegion* r = heap_region_containing(old);
4497 if (!r->evacuation_failed()) {
4498 r->set_evacuation_failed(true);
4499 _hr_printer.evac_failure(r);
4500 }
4501
4502 push_on_evac_failure_scan_stack(old);
4503
4504 if (!_drain_in_progress) {
4505 // prevent recursion in copy_to_survivor_space()
4506 _drain_in_progress = true;
4507 drain_evac_failure_scan_stack();
4508 _drain_in_progress = false;
4509 }
4510 }
4511
4512 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4513 assert(evacuation_failed(), "Oversaving!");
4514 // We want to call the "for_promotion_failure" version only in the
4515 // case of a promotion failure.
4516 if (m->must_be_preserved_for_promotion_failure(obj)) {
4517 _objs_with_preserved_marks.push(obj);
4518 _preserved_marks_of_objs.push(m);
4519 }
4520 }
4521
4522 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4523 size_t word_size) {
4524 if (purpose == GCAllocForSurvived) {
4525 HeapWord* result = survivor_attempt_allocation(word_size);
4526 if (result != NULL) {
4527 return result;
4528 } else {
4529 // Let's try to allocate in the old gen in case we can fit the
4530 // object there.
4531 return old_attempt_allocation(word_size);
4532 }
4533 } else {
4534 assert(purpose == GCAllocForTenured, "sanity");
4535 HeapWord* result = old_attempt_allocation(word_size);
4536 if (result != NULL) {
4537 return result;
4538 } else {
4539 // Let's try to allocate in the survivors in case we can fit the
4540 // object there.
4541 return survivor_attempt_allocation(word_size);
4542 }
4543 }
4544
4545 ShouldNotReachHere();
4546 // Trying to keep some compilers happy.
4547 return NULL;
4548 }
4549
4550 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4551 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4552
4553 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4554 : _g1h(g1h),
4555 _refs(g1h->task_queue(queue_num)),
4556 _dcq(&g1h->dirty_card_queue_set()),
4557 _ct_bs(g1h->g1_barrier_set()),
4558 _g1_rem(g1h->g1_rem_set()),
4559 _hash_seed(17), _queue_num(queue_num),
4560 _term_attempts(0),
4561 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4562 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4563 _age_table(false), _scanner(g1h, this, rp),
4564 _strong_roots_time(0), _term_time(0),
4565 _alloc_buffer_waste(0), _undo_waste(0) {
4566 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4567 // we "sacrifice" entry 0 to keep track of surviving bytes for
4568 // non-young regions (where the age is -1)
4569 // We also add a few elements at the beginning and at the end in
4570 // an attempt to eliminate cache contention
4571 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4572 uint array_length = PADDING_ELEM_NUM +
4573 real_length +
4574 PADDING_ELEM_NUM;
4575 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4576 if (_surviving_young_words_base == NULL)
4577 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4578 "Not enough space for young surv histo.");
4579 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4580 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4581
4582 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4583 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4584
4585 _start = os::elapsedTime();
4586 }
4587
4588 void
4589 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4590 {
4591 st->print_raw_cr("GC Termination Stats");
4592 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4593 " ------waste (KiB)------");
4594 st->print_raw_cr("thr ms ms % ms % attempts"
4595 " total alloc undo");
4596 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4597 " ------- ------- -------");
4598 }
4599
4600 void
4601 G1ParScanThreadState::print_termination_stats(int i,
4602 outputStream* const st) const
4603 {
4604 const double elapsed_ms = elapsed_time() * 1000.0;
4605 const double s_roots_ms = strong_roots_time() * 1000.0;
4606 const double term_ms = term_time() * 1000.0;
4607 st->print_cr("%3d %9.2f %9.2f %6.2f "
4608 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4609 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4610 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4611 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4612 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4613 alloc_buffer_waste() * HeapWordSize / K,
4614 undo_waste() * HeapWordSize / K);
4615 }
4616
4617 #ifdef ASSERT
4618 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4619 assert(ref != NULL, "invariant");
4620 assert(UseCompressedOops, "sanity");
4621 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4622 oop p = oopDesc::load_decode_heap_oop(ref);
4623 assert(_g1h->is_in_g1_reserved(p),
4624 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4625 return true;
4626 }
4627
4628 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4629 assert(ref != NULL, "invariant");
4630 if (has_partial_array_mask(ref)) {
4631 // Must be in the collection set--it's already been copied.
4632 oop p = clear_partial_array_mask(ref);
4633 assert(_g1h->obj_in_cs(p),
4634 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4635 } else {
4636 oop p = oopDesc::load_decode_heap_oop(ref);
4637 assert(_g1h->is_in_g1_reserved(p),
4638 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4639 }
4640 return true;
4641 }
4642
4643 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4644 if (ref.is_narrow()) {
4645 return verify_ref((narrowOop*) ref);
4646 } else {
4647 return verify_ref((oop*) ref);
4648 }
4649 }
4650 #endif // ASSERT
4651
4652 void G1ParScanThreadState::trim_queue() {
4653 assert(_evac_failure_cl != NULL, "not set");
4654
4655 StarTask ref;
4656 do {
4657 // Drain the overflow stack first, so other threads can steal.
4658 while (refs()->pop_overflow(ref)) {
4659 deal_with_reference(ref);
4660 }
4661
4662 while (refs()->pop_local(ref)) {
4663 deal_with_reference(ref);
4664 }
4665 } while (!refs()->is_empty());
4666 }
4667
4668 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4669 G1ParScanThreadState* par_scan_state) :
4670 _g1(g1), _par_scan_state(par_scan_state),
4671 _worker_id(par_scan_state->queue_num()) { }
4672
4673 void G1ParCopyHelper::mark_object(oop obj) {
4674 #ifdef ASSERT
4675 HeapRegion* hr = _g1->heap_region_containing(obj);
4676 assert(hr != NULL, "sanity");
4677 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4678 #endif // ASSERT
4679
4680 // We know that the object is not moving so it's safe to read its size.
4681 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4682 }
4683
4684 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4685 #ifdef ASSERT
4686 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4687 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4688 assert(from_obj != to_obj, "should not be self-forwarded");
4689
4690 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4691 assert(from_hr != NULL, "sanity");
4692 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4693
4694 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4695 assert(to_hr != NULL, "sanity");
4696 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4697 #endif // ASSERT
4698
4699 // The object might be in the process of being copied by another
4700 // worker so we cannot trust that its to-space image is
4701 // well-formed. So we have to read its size from its from-space
4702 // image which we know should not be changing.
4703 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4704 }
4705
4706 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4707 size_t word_sz = old->size();
4708 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4709 // +1 to make the -1 indexes valid...
4710 int young_index = from_region->young_index_in_cset()+1;
4711 assert( (from_region->is_young() && young_index > 0) ||
4712 (!from_region->is_young() && young_index == 0), "invariant" );
4713 G1CollectorPolicy* g1p = _g1h->g1_policy();
4714 markOop m = old->mark();
4715 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4716 : m->age();
4717 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4718 word_sz);
4719 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4720 #ifndef PRODUCT
4721 // Should this evacuation fail?
4722 if (_g1h->evacuation_should_fail()) {
4723 if (obj_ptr != NULL) {
4724 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4725 obj_ptr = NULL;
4726 }
4727 }
4728 #endif // !PRODUCT
4729
4730 if (obj_ptr == NULL) {
4731 // This will either forward-to-self, or detect that someone else has
4732 // installed a forwarding pointer.
4733 return _g1h->handle_evacuation_failure_par(this, old);
4734 }
4735
4736 oop obj = oop(obj_ptr);
4737
4738 // We're going to allocate linearly, so might as well prefetch ahead.
4739 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4740
4741 oop forward_ptr = old->forward_to_atomic(obj);
4742 if (forward_ptr == NULL) {
4743 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4744
4745 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4746 // we actually allocated from and update alloc_purpose accordingly
4747 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4748 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4749
4750 if (g1p->track_object_age(alloc_purpose)) {
4751 // We could simply do obj->incr_age(). However, this causes a
4752 // performance issue. obj->incr_age() will first check whether
4753 // the object has a displaced mark by checking its mark word;
4754 // getting the mark word from the new location of the object
4755 // stalls. So, given that we already have the mark word and we
4756 // are about to install it anyway, it's better to increase the
4757 // age on the mark word, when the object does not have a
4758 // displaced mark word. We're not expecting many objects to have
4759 // a displaced marked word, so that case is not optimized
4760 // further (it could be...) and we simply call obj->incr_age().
4761
4762 if (m->has_displaced_mark_helper()) {
4763 // in this case, we have to install the mark word first,
4764 // otherwise obj looks to be forwarded (the old mark word,
4765 // which contains the forward pointer, was copied)
4766 obj->set_mark(m);
4767 obj->incr_age();
4768 } else {
4769 m = m->incr_age();
4770 obj->set_mark(m);
4771 }
4772 age_table()->add(obj, word_sz);
4773 } else {
4774 obj->set_mark(m);
4775 }
4776
4777 if (G1StringDedup::is_enabled()) {
4778 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4779 to_region->is_young(),
4780 queue_num(),
4781 obj);
4782 }
4783
4784 size_t* surv_young_words = surviving_young_words();
4785 surv_young_words[young_index] += word_sz;
4786
4787 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4788 // We keep track of the next start index in the length field of
4789 // the to-space object. The actual length can be found in the
4790 // length field of the from-space object.
4791 arrayOop(obj)->set_length(0);
4792 oop* old_p = set_partial_array_mask(old);
4793 push_on_queue(old_p);
4794 } else {
4795 // No point in using the slower heap_region_containing() method,
4796 // given that we know obj is in the heap.
4797 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4798 obj->oop_iterate_backwards(&_scanner);
4799 }
4800 } else {
4801 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4802 obj = forward_ptr;
4803 }
4804 return obj;
4805 }
4806
4807 template <class T>
4808 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4809 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4810 _scanned_klass->record_modified_oops();
4811 }
4812 }
4813
4814 template <G1Barrier barrier, bool do_mark_object>
4815 template <class T>
4816 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4817 T heap_oop = oopDesc::load_heap_oop(p);
4818
4819 if (oopDesc::is_null(heap_oop)) {
4820 return;
4821 }
4822
4823 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4824
4825 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4826
4827 if (_g1->in_cset_fast_test(obj)) {
4828 oop forwardee;
4829 if (obj->is_forwarded()) {
4830 forwardee = obj->forwardee();
4831 } else {
4832 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4833 }
4834 assert(forwardee != NULL, "forwardee should not be NULL");
4835 oopDesc::encode_store_heap_oop(p, forwardee);
4836 if (do_mark_object && forwardee != obj) {
4837 // If the object is self-forwarded we don't need to explicitly
4838 // mark it, the evacuation failure protocol will do so.
4839 mark_forwarded_object(obj, forwardee);
4840 }
4841
4842 if (barrier == G1BarrierKlass) {
4843 do_klass_barrier(p, forwardee);
4844 }
4845 } else {
4846 // The object is not in collection set. If we're a root scanning
4847 // closure during an initial mark pause (i.e. do_mark_object will
4848 // be true) then attempt to mark the object.
4849 if (do_mark_object) {
4850 mark_object(obj);
4851 }
4852 }
4853
4854 if (barrier == G1BarrierEvac) {
4855 _par_scan_state->update_rs(_from, p, _worker_id);
4856 }
4857 }
4858
4859 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4860 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4861
4862 class G1ParEvacuateFollowersClosure : public VoidClosure {
4863 protected:
4864 G1CollectedHeap* _g1h;
4865 G1ParScanThreadState* _par_scan_state;
4866 RefToScanQueueSet* _queues;
4867 ParallelTaskTerminator* _terminator;
4868
4869 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4870 RefToScanQueueSet* queues() { return _queues; }
4871 ParallelTaskTerminator* terminator() { return _terminator; }
4872
4873 public:
4874 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4875 G1ParScanThreadState* par_scan_state,
4876 RefToScanQueueSet* queues,
4877 ParallelTaskTerminator* terminator)
4878 : _g1h(g1h), _par_scan_state(par_scan_state),
4879 _queues(queues), _terminator(terminator) {}
4880
4881 void do_void();
4882
4883 private:
4884 inline bool offer_termination();
4885 };
4886
4887 bool G1ParEvacuateFollowersClosure::offer_termination() {
4888 G1ParScanThreadState* const pss = par_scan_state();
4889 pss->start_term_time();
4890 const bool res = terminator()->offer_termination();
4891 pss->end_term_time();
4892 return res;
4893 }
4894
4895 void G1ParEvacuateFollowersClosure::do_void() {
4896 StarTask stolen_task;
4897 G1ParScanThreadState* const pss = par_scan_state();
4898 pss->trim_queue();
4899
4900 do {
4901 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4902 assert(pss->verify_task(stolen_task), "sanity");
4903 if (stolen_task.is_narrow()) {
4904 pss->deal_with_reference((narrowOop*) stolen_task);
4905 } else {
4906 pss->deal_with_reference((oop*) stolen_task);
4907 }
4908
4909 // We've just processed a reference and we might have made
4910 // available new entries on the queues. So we have to make sure
4911 // we drain the queues as necessary.
4912 pss->trim_queue();
4913 }
4914 } while (!offer_termination());
4915
4916 pss->retire_alloc_buffers();
4917 }
4918
4919 class G1KlassScanClosure : public KlassClosure {
4920 G1ParCopyHelper* _closure;
4921 bool _process_only_dirty;
4922 int _count;
4923 public:
4924 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4925 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4926 void do_klass(Klass* klass) {
4927 // If the klass has not been dirtied we know that there's
4928 // no references into the young gen and we can skip it.
4929 if (!_process_only_dirty || klass->has_modified_oops()) {
4930 // Clean the klass since we're going to scavenge all the metadata.
4931 klass->clear_modified_oops();
4932
4933 // Tell the closure that this klass is the Klass to scavenge
4934 // and is the one to dirty if oops are left pointing into the young gen.
4935 _closure->set_scanned_klass(klass);
4936
4937 klass->oops_do(_closure);
4938
4939 _closure->set_scanned_klass(NULL);
4940 }
4941 _count++;
4942 }
4943 };
4944
4945 class G1ParTask : public AbstractGangTask {
4946 protected:
4947 G1CollectedHeap* _g1h;
4948 RefToScanQueueSet *_queues;
4949 ParallelTaskTerminator _terminator;
4950 uint _n_workers;
4951
4952 Mutex _stats_lock;
4953 Mutex* stats_lock() { return &_stats_lock; }
4954
4955 size_t getNCards() {
4956 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4957 / G1BlockOffsetSharedArray::N_bytes;
4958 }
4959
4960 public:
4961 G1ParTask(G1CollectedHeap* g1h,
4962 RefToScanQueueSet *task_queues)
4963 : AbstractGangTask("G1 collection"),
4964 _g1h(g1h),
4965 _queues(task_queues),
4966 _terminator(0, _queues),
4967 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4968 {}
4969
4970 RefToScanQueueSet* queues() { return _queues; }
4971
4972 RefToScanQueue *work_queue(int i) {
4973 return queues()->queue(i);
4974 }
4975
4976 ParallelTaskTerminator* terminator() { return &_terminator; }
4977
4978 virtual void set_for_termination(int active_workers) {
4979 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4980 // in the young space (_par_seq_tasks) in the G1 heap
4981 // for SequentialSubTasksDone.
4982 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4983 // both of which need setting by set_n_termination().
4984 _g1h->SharedHeap::set_n_termination(active_workers);
4985 _g1h->set_n_termination(active_workers);
4986 terminator()->reset_for_reuse(active_workers);
4987 _n_workers = active_workers;
4988 }
4989
4990 void work(uint worker_id) {
4991 if (worker_id >= _n_workers) return; // no work needed this round
4992
4993 double start_time_ms = os::elapsedTime() * 1000.0;
4994 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4995
4996 {
4997 ResourceMark rm;
4998 HandleMark hm;
4999
5000 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5001
5002 G1ParScanThreadState pss(_g1h, worker_id, rp);
5003 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5004
5005 pss.set_evac_failure_closure(&evac_failure_cl);
5006
5007 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5008 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5009
5010 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5011 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5012
5013 bool only_young = _g1h->g1_policy()->gcs_are_young();
5014 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5015 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5016
5017 OopClosure* scan_root_cl = &only_scan_root_cl;
5018 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5019
5020 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5021 // We also need to mark copied objects.
5022 scan_root_cl = &scan_mark_root_cl;
5023 scan_klasses_cl = &scan_mark_klasses_cl_s;
5024 }
5025
5026 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5027
5028 // Don't scan the scavengable methods in the code cache as part
5029 // of strong root scanning. The code roots that point into a
5030 // region in the collection set are scanned when we scan the
5031 // region's RSet.
5032 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5033
5034 pss.start_strong_roots();
5035 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5036 SharedHeap::ScanningOption(so),
5037 scan_root_cl,
5038 &push_heap_rs_cl,
5039 scan_klasses_cl,
5040 worker_id);
5041 pss.end_strong_roots();
5042
5043 {
5044 double start = os::elapsedTime();
5045 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5046 evac.do_void();
5047 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5048 double term_ms = pss.term_time()*1000.0;
5049 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5050 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5051 }
5052 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5053 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5054
5055 if (ParallelGCVerbose) {
5056 MutexLocker x(stats_lock());
5057 pss.print_termination_stats(worker_id);
5058 }
5059
5060 assert(pss.refs()->is_empty(), "should be empty");
5061
5062 // Close the inner scope so that the ResourceMark and HandleMark
5063 // destructors are executed here and are included as part of the
5064 // "GC Worker Time".
5065 }
5066
5067 double end_time_ms = os::elapsedTime() * 1000.0;
5068 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5069 }
5070 };
5071
5072 // *** Common G1 Evacuation Stuff
5073
5074 // This method is run in a GC worker.
5075
5076 void
5077 G1CollectedHeap::
5078 g1_process_strong_roots(bool is_scavenging,
5079 ScanningOption so,
5080 OopClosure* scan_non_heap_roots,
5081 OopsInHeapRegionClosure* scan_rs,
5082 G1KlassScanClosure* scan_klasses,
5083 int worker_i) {
5084
5085 // First scan the strong roots
5086 double ext_roots_start = os::elapsedTime();
5087 double closure_app_time_sec = 0.0;
5088
5089 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5090
5091 process_strong_roots(false, // no scoping; this is parallel code
5092 so,
5093 &buf_scan_non_heap_roots,
5094 scan_klasses
5095 );
5096
5097 // Now the CM ref_processor roots.
5098 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5099 // We need to treat the discovered reference lists of the
5100 // concurrent mark ref processor as roots and keep entries
5101 // (which are added by the marking threads) on them live
5102 // until they can be processed at the end of marking.
5103 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5104 }
5105
5106 // Finish up any enqueued closure apps (attributed as object copy time).
5107 buf_scan_non_heap_roots.done();
5108
5109 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5110
5111 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5112
5113 double ext_root_time_ms =
5114 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5115
5116 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5117
5118 // During conc marking we have to filter the per-thread SATB buffers
5119 // to make sure we remove any oops into the CSet (which will show up
5120 // as implicitly live).
5121 double satb_filtering_ms = 0.0;
5122 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5123 if (mark_in_progress()) {
5124 double satb_filter_start = os::elapsedTime();
5125
5126 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5127
5128 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5129 }
5130 }
5131 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5132
5133 // If this is an initial mark pause, and we're not scanning
5134 // the entire code cache, we need to mark the oops in the
5135 // strong code root lists for the regions that are not in
5136 // the collection set.
5137 // Note all threads participate in this set of root tasks.
5138 double mark_strong_code_roots_ms = 0.0;
5139 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5140 double mark_strong_roots_start = os::elapsedTime();
5141 mark_strong_code_roots(worker_i);
5142 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5143 }
5144 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5145
5146 // Now scan the complement of the collection set.
5147 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5148 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5149
5150 _process_strong_tasks->all_tasks_completed();
5151 }
5152
5153 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5154 private:
5155 BoolObjectClosure* _is_alive;
5156 int _initial_string_table_size;
5157 int _initial_symbol_table_size;
5158
5159 bool _process_strings;
5160 int _strings_processed;
5161 int _strings_removed;
5162
5163 bool _process_symbols;
5164 int _symbols_processed;
5165 int _symbols_removed;
5166
5167 bool _do_in_parallel;
5168 public:
5169 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5170 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5171 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5172 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5173 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5174
5175 _initial_string_table_size = StringTable::the_table()->table_size();
5176 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5177 if (process_strings) {
5178 StringTable::clear_parallel_claimed_index();
5179 }
5180 if (process_symbols) {
5181 SymbolTable::clear_parallel_claimed_index();
5182 }
5183 }
5184
5185 ~G1StringSymbolTableUnlinkTask() {
5186 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5187 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5188 StringTable::parallel_claimed_index(), _initial_string_table_size));
5189 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5190 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5191 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5192 }
5193
5194 void work(uint worker_id) {
5195 if (_do_in_parallel) {
5196 int strings_processed = 0;
5197 int strings_removed = 0;
5198 int symbols_processed = 0;
5199 int symbols_removed = 0;
5200 if (_process_strings) {
5201 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5202 Atomic::add(strings_processed, &_strings_processed);
5203 Atomic::add(strings_removed, &_strings_removed);
5204 }
5205 if (_process_symbols) {
5206 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5207 Atomic::add(symbols_processed, &_symbols_processed);
5208 Atomic::add(symbols_removed, &_symbols_removed);
5209 }
5210 } else {
5211 if (_process_strings) {
5212 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5213 }
5214 if (_process_symbols) {
5215 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5216 }
5217 }
5218 }
5219
5220 size_t strings_processed() const { return (size_t)_strings_processed; }
5221 size_t strings_removed() const { return (size_t)_strings_removed; }
5222
5223 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5224 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5225 };
5226
5227 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5228 bool process_strings, bool process_symbols) {
5229 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5230 _g1h->workers()->active_workers() : 1);
5231
5232 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5233 if (G1CollectedHeap::use_parallel_gc_threads()) {
5234 set_par_threads(n_workers);
5235 workers()->run_task(&g1_unlink_task);
5236 set_par_threads(0);
5237 } else {
5238 g1_unlink_task.work(0);
5239 }
5240 if (G1TraceStringSymbolTableScrubbing) {
5241 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5242 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5243 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5244 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5245 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5246 }
5247
5248 if (G1StringDedup::is_enabled()) {
5249 G1StringDedup::unlink(is_alive);
5250 }
5251 }
5252
5253 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
5254 public:
5255 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
5256 *card_ptr = CardTableModRefBS::dirty_card_val();
5257 return true;
5258 }
5259 };
5260
5261 void G1CollectedHeap::redirty_logged_cards() {
5262 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5263 double redirty_logged_cards_start = os::elapsedTime();
5264
5265 RedirtyLoggedCardTableEntryFastClosure redirty;
5266 dirty_card_queue_set().set_closure(&redirty);
5267 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5268
5269 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5270 dcq.merge_bufferlists(&dirty_card_queue_set());
5271 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5272
5273 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5274 }
5275
5276 // Weak Reference Processing support
5277
5278 // An always "is_alive" closure that is used to preserve referents.
5279 // If the object is non-null then it's alive. Used in the preservation
5280 // of referent objects that are pointed to by reference objects
5281 // discovered by the CM ref processor.
5282 class G1AlwaysAliveClosure: public BoolObjectClosure {
5283 G1CollectedHeap* _g1;
5284 public:
5285 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5286 bool do_object_b(oop p) {
5287 if (p != NULL) {
5288 return true;
5289 }
5290 return false;
5291 }
5292 };
5293
5294 bool G1STWIsAliveClosure::do_object_b(oop p) {
5295 // An object is reachable if it is outside the collection set,
5296 // or is inside and copied.
5297 return !_g1->obj_in_cs(p) || p->is_forwarded();
5298 }
5299
5300 // Non Copying Keep Alive closure
5301 class G1KeepAliveClosure: public OopClosure {
5302 G1CollectedHeap* _g1;
5303 public:
5304 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5305 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5306 void do_oop( oop* p) {
5307 oop obj = *p;
5308
5309 if (_g1->obj_in_cs(obj)) {
5310 assert( obj->is_forwarded(), "invariant" );
5311 *p = obj->forwardee();
5312 }
5313 }
5314 };
5315
5316 // Copying Keep Alive closure - can be called from both
5317 // serial and parallel code as long as different worker
5318 // threads utilize different G1ParScanThreadState instances
5319 // and different queues.
5320
5321 class G1CopyingKeepAliveClosure: public OopClosure {
5322 G1CollectedHeap* _g1h;
5323 OopClosure* _copy_non_heap_obj_cl;
5324 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5325 G1ParScanThreadState* _par_scan_state;
5326
5327 public:
5328 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5329 OopClosure* non_heap_obj_cl,
5330 OopsInHeapRegionClosure* metadata_obj_cl,
5331 G1ParScanThreadState* pss):
5332 _g1h(g1h),
5333 _copy_non_heap_obj_cl(non_heap_obj_cl),
5334 _copy_metadata_obj_cl(metadata_obj_cl),
5335 _par_scan_state(pss)
5336 {}
5337
5338 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5339 virtual void do_oop( oop* p) { do_oop_work(p); }
5340
5341 template <class T> void do_oop_work(T* p) {
5342 oop obj = oopDesc::load_decode_heap_oop(p);
5343
5344 if (_g1h->obj_in_cs(obj)) {
5345 // If the referent object has been forwarded (either copied
5346 // to a new location or to itself in the event of an
5347 // evacuation failure) then we need to update the reference
5348 // field and, if both reference and referent are in the G1
5349 // heap, update the RSet for the referent.
5350 //
5351 // If the referent has not been forwarded then we have to keep
5352 // it alive by policy. Therefore we have copy the referent.
5353 //
5354 // If the reference field is in the G1 heap then we can push
5355 // on the PSS queue. When the queue is drained (after each
5356 // phase of reference processing) the object and it's followers
5357 // will be copied, the reference field set to point to the
5358 // new location, and the RSet updated. Otherwise we need to
5359 // use the the non-heap or metadata closures directly to copy
5360 // the referent object and update the pointer, while avoiding
5361 // updating the RSet.
5362
5363 if (_g1h->is_in_g1_reserved(p)) {
5364 _par_scan_state->push_on_queue(p);
5365 } else {
5366 assert(!ClassLoaderDataGraph::contains((address)p),
5367 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5368 PTR_FORMAT, p));
5369 _copy_non_heap_obj_cl->do_oop(p);
5370 }
5371 }
5372 }
5373 };
5374
5375 // Serial drain queue closure. Called as the 'complete_gc'
5376 // closure for each discovered list in some of the
5377 // reference processing phases.
5378
5379 class G1STWDrainQueueClosure: public VoidClosure {
5380 protected:
5381 G1CollectedHeap* _g1h;
5382 G1ParScanThreadState* _par_scan_state;
5383
5384 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5385
5386 public:
5387 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5388 _g1h(g1h),
5389 _par_scan_state(pss)
5390 { }
5391
5392 void do_void() {
5393 G1ParScanThreadState* const pss = par_scan_state();
5394 pss->trim_queue();
5395 }
5396 };
5397
5398 // Parallel Reference Processing closures
5399
5400 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5401 // processing during G1 evacuation pauses.
5402
5403 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5404 private:
5405 G1CollectedHeap* _g1h;
5406 RefToScanQueueSet* _queues;
5407 FlexibleWorkGang* _workers;
5408 int _active_workers;
5409
5410 public:
5411 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5412 FlexibleWorkGang* workers,
5413 RefToScanQueueSet *task_queues,
5414 int n_workers) :
5415 _g1h(g1h),
5416 _queues(task_queues),
5417 _workers(workers),
5418 _active_workers(n_workers)
5419 {
5420 assert(n_workers > 0, "shouldn't call this otherwise");
5421 }
5422
5423 // Executes the given task using concurrent marking worker threads.
5424 virtual void execute(ProcessTask& task);
5425 virtual void execute(EnqueueTask& task);
5426 };
5427
5428 // Gang task for possibly parallel reference processing
5429
5430 class G1STWRefProcTaskProxy: public AbstractGangTask {
5431 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5432 ProcessTask& _proc_task;
5433 G1CollectedHeap* _g1h;
5434 RefToScanQueueSet *_task_queues;
5435 ParallelTaskTerminator* _terminator;
5436
5437 public:
5438 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5439 G1CollectedHeap* g1h,
5440 RefToScanQueueSet *task_queues,
5441 ParallelTaskTerminator* terminator) :
5442 AbstractGangTask("Process reference objects in parallel"),
5443 _proc_task(proc_task),
5444 _g1h(g1h),
5445 _task_queues(task_queues),
5446 _terminator(terminator)
5447 {}
5448
5449 virtual void work(uint worker_id) {
5450 // The reference processing task executed by a single worker.
5451 ResourceMark rm;
5452 HandleMark hm;
5453
5454 G1STWIsAliveClosure is_alive(_g1h);
5455
5456 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5457 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5458
5459 pss.set_evac_failure_closure(&evac_failure_cl);
5460
5461 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5462 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5463
5464 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5465 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5466
5467 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5468 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5469
5470 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5471 // We also need to mark copied objects.
5472 copy_non_heap_cl = ©_mark_non_heap_cl;
5473 copy_metadata_cl = ©_mark_metadata_cl;
5474 }
5475
5476 // Keep alive closure.
5477 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5478
5479 // Complete GC closure
5480 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5481
5482 // Call the reference processing task's work routine.
5483 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5484
5485 // Note we cannot assert that the refs array is empty here as not all
5486 // of the processing tasks (specifically phase2 - pp2_work) execute
5487 // the complete_gc closure (which ordinarily would drain the queue) so
5488 // the queue may not be empty.
5489 }
5490 };
5491
5492 // Driver routine for parallel reference processing.
5493 // Creates an instance of the ref processing gang
5494 // task and has the worker threads execute it.
5495 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5496 assert(_workers != NULL, "Need parallel worker threads.");
5497
5498 ParallelTaskTerminator terminator(_active_workers, _queues);
5499 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5500
5501 _g1h->set_par_threads(_active_workers);
5502 _workers->run_task(&proc_task_proxy);
5503 _g1h->set_par_threads(0);
5504 }
5505
5506 // Gang task for parallel reference enqueueing.
5507
5508 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5509 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5510 EnqueueTask& _enq_task;
5511
5512 public:
5513 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5514 AbstractGangTask("Enqueue reference objects in parallel"),
5515 _enq_task(enq_task)
5516 { }
5517
5518 virtual void work(uint worker_id) {
5519 _enq_task.work(worker_id);
5520 }
5521 };
5522
5523 // Driver routine for parallel reference enqueueing.
5524 // Creates an instance of the ref enqueueing gang
5525 // task and has the worker threads execute it.
5526
5527 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5528 assert(_workers != NULL, "Need parallel worker threads.");
5529
5530 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5531
5532 _g1h->set_par_threads(_active_workers);
5533 _workers->run_task(&enq_task_proxy);
5534 _g1h->set_par_threads(0);
5535 }
5536
5537 // End of weak reference support closures
5538
5539 // Abstract task used to preserve (i.e. copy) any referent objects
5540 // that are in the collection set and are pointed to by reference
5541 // objects discovered by the CM ref processor.
5542
5543 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5544 protected:
5545 G1CollectedHeap* _g1h;
5546 RefToScanQueueSet *_queues;
5547 ParallelTaskTerminator _terminator;
5548 uint _n_workers;
5549
5550 public:
5551 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5552 AbstractGangTask("ParPreserveCMReferents"),
5553 _g1h(g1h),
5554 _queues(task_queues),
5555 _terminator(workers, _queues),
5556 _n_workers(workers)
5557 { }
5558
5559 void work(uint worker_id) {
5560 ResourceMark rm;
5561 HandleMark hm;
5562
5563 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5564 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5565
5566 pss.set_evac_failure_closure(&evac_failure_cl);
5567
5568 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5569
5570
5571 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5572 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5573
5574 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5575 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5576
5577 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5578 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5579
5580 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5581 // We also need to mark copied objects.
5582 copy_non_heap_cl = ©_mark_non_heap_cl;
5583 copy_metadata_cl = ©_mark_metadata_cl;
5584 }
5585
5586 // Is alive closure
5587 G1AlwaysAliveClosure always_alive(_g1h);
5588
5589 // Copying keep alive closure. Applied to referent objects that need
5590 // to be copied.
5591 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5592
5593 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5594
5595 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5596 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5597
5598 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5599 // So this must be true - but assert just in case someone decides to
5600 // change the worker ids.
5601 assert(0 <= worker_id && worker_id < limit, "sanity");
5602 assert(!rp->discovery_is_atomic(), "check this code");
5603
5604 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5605 for (uint idx = worker_id; idx < limit; idx += stride) {
5606 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5607
5608 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5609 while (iter.has_next()) {
5610 // Since discovery is not atomic for the CM ref processor, we
5611 // can see some null referent objects.
5612 iter.load_ptrs(DEBUG_ONLY(true));
5613 oop ref = iter.obj();
5614
5615 // This will filter nulls.
5616 if (iter.is_referent_alive()) {
5617 iter.make_referent_alive();
5618 }
5619 iter.move_to_next();
5620 }
5621 }
5622
5623 // Drain the queue - which may cause stealing
5624 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5625 drain_queue.do_void();
5626 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5627 assert(pss.refs()->is_empty(), "should be");
5628 }
5629 };
5630
5631 // Weak Reference processing during an evacuation pause (part 1).
5632 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5633 double ref_proc_start = os::elapsedTime();
5634
5635 ReferenceProcessor* rp = _ref_processor_stw;
5636 assert(rp->discovery_enabled(), "should have been enabled");
5637
5638 // Any reference objects, in the collection set, that were 'discovered'
5639 // by the CM ref processor should have already been copied (either by
5640 // applying the external root copy closure to the discovered lists, or
5641 // by following an RSet entry).
5642 //
5643 // But some of the referents, that are in the collection set, that these
5644 // reference objects point to may not have been copied: the STW ref
5645 // processor would have seen that the reference object had already
5646 // been 'discovered' and would have skipped discovering the reference,
5647 // but would not have treated the reference object as a regular oop.
5648 // As a result the copy closure would not have been applied to the
5649 // referent object.
5650 //
5651 // We need to explicitly copy these referent objects - the references
5652 // will be processed at the end of remarking.
5653 //
5654 // We also need to do this copying before we process the reference
5655 // objects discovered by the STW ref processor in case one of these
5656 // referents points to another object which is also referenced by an
5657 // object discovered by the STW ref processor.
5658
5659 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5660 no_of_gc_workers == workers()->active_workers(),
5661 "Need to reset active GC workers");
5662
5663 set_par_threads(no_of_gc_workers);
5664 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5665 no_of_gc_workers,
5666 _task_queues);
5667
5668 if (G1CollectedHeap::use_parallel_gc_threads()) {
5669 workers()->run_task(&keep_cm_referents);
5670 } else {
5671 keep_cm_referents.work(0);
5672 }
5673
5674 set_par_threads(0);
5675
5676 // Closure to test whether a referent is alive.
5677 G1STWIsAliveClosure is_alive(this);
5678
5679 // Even when parallel reference processing is enabled, the processing
5680 // of JNI refs is serial and performed serially by the current thread
5681 // rather than by a worker. The following PSS will be used for processing
5682 // JNI refs.
5683
5684 // Use only a single queue for this PSS.
5685 G1ParScanThreadState pss(this, 0, NULL);
5686
5687 // We do not embed a reference processor in the copying/scanning
5688 // closures while we're actually processing the discovered
5689 // reference objects.
5690 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5691
5692 pss.set_evac_failure_closure(&evac_failure_cl);
5693
5694 assert(pss.refs()->is_empty(), "pre-condition");
5695
5696 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5697 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5698
5699 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5700 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5701
5702 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5703 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5704
5705 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5706 // We also need to mark copied objects.
5707 copy_non_heap_cl = ©_mark_non_heap_cl;
5708 copy_metadata_cl = ©_mark_metadata_cl;
5709 }
5710
5711 // Keep alive closure.
5712 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5713
5714 // Serial Complete GC closure
5715 G1STWDrainQueueClosure drain_queue(this, &pss);
5716
5717 // Setup the soft refs policy...
5718 rp->setup_policy(false);
5719
5720 ReferenceProcessorStats stats;
5721 if (!rp->processing_is_mt()) {
5722 // Serial reference processing...
5723 stats = rp->process_discovered_references(&is_alive,
5724 &keep_alive,
5725 &drain_queue,
5726 NULL,
5727 _gc_timer_stw);
5728 } else {
5729 // Parallel reference processing
5730 assert(rp->num_q() == no_of_gc_workers, "sanity");
5731 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5732
5733 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5734 stats = rp->process_discovered_references(&is_alive,
5735 &keep_alive,
5736 &drain_queue,
5737 &par_task_executor,
5738 _gc_timer_stw);
5739 }
5740
5741 _gc_tracer_stw->report_gc_reference_stats(stats);
5742 // We have completed copying any necessary live referent objects
5743 // (that were not copied during the actual pause) so we can
5744 // retire any active alloc buffers
5745 pss.retire_alloc_buffers();
5746 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5747
5748 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5749 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5750 }
5751
5752 // Weak Reference processing during an evacuation pause (part 2).
5753 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5754 double ref_enq_start = os::elapsedTime();
5755
5756 ReferenceProcessor* rp = _ref_processor_stw;
5757 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5758
5759 // Now enqueue any remaining on the discovered lists on to
5760 // the pending list.
5761 if (!rp->processing_is_mt()) {
5762 // Serial reference processing...
5763 rp->enqueue_discovered_references();
5764 } else {
5765 // Parallel reference enqueueing
5766
5767 assert(no_of_gc_workers == workers()->active_workers(),
5768 "Need to reset active workers");
5769 assert(rp->num_q() == no_of_gc_workers, "sanity");
5770 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5771
5772 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5773 rp->enqueue_discovered_references(&par_task_executor);
5774 }
5775
5776 rp->verify_no_references_recorded();
5777 assert(!rp->discovery_enabled(), "should have been disabled");
5778
5779 // FIXME
5780 // CM's reference processing also cleans up the string and symbol tables.
5781 // Should we do that here also? We could, but it is a serial operation
5782 // and could significantly increase the pause time.
5783
5784 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5785 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5786 }
5787
5788 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5789 _expand_heap_after_alloc_failure = true;
5790 _evacuation_failed = false;
5791
5792 // Should G1EvacuationFailureALot be in effect for this GC?
5793 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5794
5795 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5796
5797 // Disable the hot card cache.
5798 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5799 hot_card_cache->reset_hot_cache_claimed_index();
5800 hot_card_cache->set_use_cache(false);
5801
5802 uint n_workers;
5803 if (G1CollectedHeap::use_parallel_gc_threads()) {
5804 n_workers =
5805 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5806 workers()->active_workers(),
5807 Threads::number_of_non_daemon_threads());
5808 assert(UseDynamicNumberOfGCThreads ||
5809 n_workers == workers()->total_workers(),
5810 "If not dynamic should be using all the workers");
5811 workers()->set_active_workers(n_workers);
5812 set_par_threads(n_workers);
5813 } else {
5814 assert(n_par_threads() == 0,
5815 "Should be the original non-parallel value");
5816 n_workers = 1;
5817 }
5818
5819 G1ParTask g1_par_task(this, _task_queues);
5820
5821 init_for_evac_failure(NULL);
5822
5823 rem_set()->prepare_for_younger_refs_iterate(true);
5824
5825 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5826 double start_par_time_sec = os::elapsedTime();
5827 double end_par_time_sec;
5828
5829 {
5830 StrongRootsScope srs(this);
5831
5832 if (G1CollectedHeap::use_parallel_gc_threads()) {
5833 // The individual threads will set their evac-failure closures.
5834 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5835 // These tasks use ShareHeap::_process_strong_tasks
5836 assert(UseDynamicNumberOfGCThreads ||
5837 workers()->active_workers() == workers()->total_workers(),
5838 "If not dynamic should be using all the workers");
5839 workers()->run_task(&g1_par_task);
5840 } else {
5841 g1_par_task.set_for_termination(n_workers);
5842 g1_par_task.work(0);
5843 }
5844 end_par_time_sec = os::elapsedTime();
5845
5846 // Closing the inner scope will execute the destructor
5847 // for the StrongRootsScope object. We record the current
5848 // elapsed time before closing the scope so that time
5849 // taken for the SRS destructor is NOT included in the
5850 // reported parallel time.
5851 }
5852
5853 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5854 g1_policy()->phase_times()->record_par_time(par_time_ms);
5855
5856 double code_root_fixup_time_ms =
5857 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5858 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5859
5860 set_par_threads(0);
5861
5862 // Process any discovered reference objects - we have
5863 // to do this _before_ we retire the GC alloc regions
5864 // as we may have to copy some 'reachable' referent
5865 // objects (and their reachable sub-graphs) that were
5866 // not copied during the pause.
5867 process_discovered_references(n_workers);
5868
5869 // Weak root processing.
5870 {
5871 G1STWIsAliveClosure is_alive(this);
5872 G1KeepAliveClosure keep_alive(this);
5873 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5874 if (G1StringDedup::is_enabled()) {
5875 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5876 }
5877 }
5878
5879 release_gc_alloc_regions(n_workers, evacuation_info);
5880 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5881
5882 // Reset and re-enable the hot card cache.
5883 // Note the counts for the cards in the regions in the
5884 // collection set are reset when the collection set is freed.
5885 hot_card_cache->reset_hot_cache();
5886 hot_card_cache->set_use_cache(true);
5887
5888 // Migrate the strong code roots attached to each region in
5889 // the collection set. Ideally we would like to do this
5890 // after we have finished the scanning/evacuation of the
5891 // strong code roots for a particular heap region.
5892 migrate_strong_code_roots();
5893
5894 purge_code_root_memory();
5895
5896 if (g1_policy()->during_initial_mark_pause()) {
5897 // Reset the claim values set during marking the strong code roots
5898 reset_heap_region_claim_values();
5899 }
5900
5901 finalize_for_evac_failure();
5902
5903 if (evacuation_failed()) {
5904 remove_self_forwarding_pointers();
5905
5906 // Reset the G1EvacuationFailureALot counters and flags
5907 // Note: the values are reset only when an actual
5908 // evacuation failure occurs.
5909 NOT_PRODUCT(reset_evacuation_should_fail();)
5910 }
5911
5912 // Enqueue any remaining references remaining on the STW
5913 // reference processor's discovered lists. We need to do
5914 // this after the card table is cleaned (and verified) as
5915 // the act of enqueueing entries on to the pending list
5916 // will log these updates (and dirty their associated
5917 // cards). We need these updates logged to update any
5918 // RSets.
5919 enqueue_discovered_references(n_workers);
5920
5921 if (G1DeferredRSUpdate) {
5922 redirty_logged_cards();
5923 }
5924 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5925 }
5926
5927 void G1CollectedHeap::free_region(HeapRegion* hr,
5928 FreeRegionList* free_list,
5929 bool par,
5930 bool locked) {
5931 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5932 assert(!hr->is_empty(), "the region should not be empty");
5933 assert(free_list != NULL, "pre-condition");
5934
5935 // Clear the card counts for this region.
5936 // Note: we only need to do this if the region is not young
5937 // (since we don't refine cards in young regions).
5938 if (!hr->is_young()) {
5939 _cg1r->hot_card_cache()->reset_card_counts(hr);
5940 }
5941 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5942 free_list->add_ordered(hr);
5943 }
5944
5945 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5946 FreeRegionList* free_list,
5947 bool par) {
5948 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5949 assert(free_list != NULL, "pre-condition");
5950
5951 size_t hr_capacity = hr->capacity();
5952 // We need to read this before we make the region non-humongous,
5953 // otherwise the information will be gone.
5954 uint last_index = hr->last_hc_index();
5955 hr->set_notHumongous();
5956 free_region(hr, free_list, par);
5957
5958 uint i = hr->hrs_index() + 1;
5959 while (i < last_index) {
5960 HeapRegion* curr_hr = region_at(i);
5961 assert(curr_hr->continuesHumongous(), "invariant");
5962 curr_hr->set_notHumongous();
5963 free_region(curr_hr, free_list, par);
5964 i += 1;
5965 }
5966 }
5967
5968 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5969 const HeapRegionSetCount& humongous_regions_removed) {
5970 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5971 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5972 _old_set.bulk_remove(old_regions_removed);
5973 _humongous_set.bulk_remove(humongous_regions_removed);
5974 }
5975
5976 }
5977
5978 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5979 assert(list != NULL, "list can't be null");
5980 if (!list->is_empty()) {
5981 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5982 _free_list.add_ordered(list);
5983 }
5984 }
5985
5986 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5987 assert(_summary_bytes_used >= bytes,
5988 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
5989 _summary_bytes_used, bytes));
5990 _summary_bytes_used -= bytes;
5991 }
5992
5993 class G1ParCleanupCTTask : public AbstractGangTask {
5994 G1SATBCardTableModRefBS* _ct_bs;
5995 G1CollectedHeap* _g1h;
5996 HeapRegion* volatile _su_head;
5997 public:
5998 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5999 G1CollectedHeap* g1h) :
6000 AbstractGangTask("G1 Par Cleanup CT Task"),
6001 _ct_bs(ct_bs), _g1h(g1h) { }
6002
6003 void work(uint worker_id) {
6004 HeapRegion* r;
6005 while (r = _g1h->pop_dirty_cards_region()) {
6006 clear_cards(r);
6007 }
6008 }
6009
6010 void clear_cards(HeapRegion* r) {
6011 // Cards of the survivors should have already been dirtied.
6012 if (!r->is_survivor()) {
6013 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6014 }
6015 }
6016 };
6017
6018 #ifndef PRODUCT
6019 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6020 G1CollectedHeap* _g1h;
6021 G1SATBCardTableModRefBS* _ct_bs;
6022 public:
6023 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6024 : _g1h(g1h), _ct_bs(ct_bs) { }
6025 virtual bool doHeapRegion(HeapRegion* r) {
6026 if (r->is_survivor()) {
6027 _g1h->verify_dirty_region(r);
6028 } else {
6029 _g1h->verify_not_dirty_region(r);
6030 }
6031 return false;
6032 }
6033 };
6034
6035 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6036 // All of the region should be clean.
6037 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6038 MemRegion mr(hr->bottom(), hr->end());
6039 ct_bs->verify_not_dirty_region(mr);
6040 }
6041
6042 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6043 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6044 // dirty allocated blocks as they allocate them. The thread that
6045 // retires each region and replaces it with a new one will do a
6046 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6047 // not dirty that area (one less thing to have to do while holding
6048 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6049 // is dirty.
6050 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6051 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6052 if (hr->is_young()) {
6053 ct_bs->verify_g1_young_region(mr);
6054 } else {
6055 ct_bs->verify_dirty_region(mr);
6056 }
6057 }
6058
6059 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6060 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6061 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6062 verify_dirty_region(hr);
6063 }
6064 }
6065
6066 void G1CollectedHeap::verify_dirty_young_regions() {
6067 verify_dirty_young_list(_young_list->first_region());
6068 }
6069 #endif
6070
6071 void G1CollectedHeap::cleanUpCardTable() {
6072 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6073 double start = os::elapsedTime();
6074
6075 {
6076 // Iterate over the dirty cards region list.
6077 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6078
6079 if (G1CollectedHeap::use_parallel_gc_threads()) {
6080 set_par_threads();
6081 workers()->run_task(&cleanup_task);
6082 set_par_threads(0);
6083 } else {
6084 while (_dirty_cards_region_list) {
6085 HeapRegion* r = _dirty_cards_region_list;
6086 cleanup_task.clear_cards(r);
6087 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6088 if (_dirty_cards_region_list == r) {
6089 // The last region.
6090 _dirty_cards_region_list = NULL;
6091 }
6092 r->set_next_dirty_cards_region(NULL);
6093 }
6094 }
6095 #ifndef PRODUCT
6096 if (G1VerifyCTCleanup || VerifyAfterGC) {
6097 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6098 heap_region_iterate(&cleanup_verifier);
6099 }
6100 #endif
6101 }
6102
6103 double elapsed = os::elapsedTime() - start;
6104 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6105 }
6106
6107 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6108 size_t pre_used = 0;
6109 FreeRegionList local_free_list("Local List for CSet Freeing");
6110
6111 double young_time_ms = 0.0;
6112 double non_young_time_ms = 0.0;
6113
6114 // Since the collection set is a superset of the the young list,
6115 // all we need to do to clear the young list is clear its
6116 // head and length, and unlink any young regions in the code below
6117 _young_list->clear();
6118
6119 G1CollectorPolicy* policy = g1_policy();
6120
6121 double start_sec = os::elapsedTime();
6122 bool non_young = true;
6123
6124 HeapRegion* cur = cs_head;
6125 int age_bound = -1;
6126 size_t rs_lengths = 0;
6127
6128 while (cur != NULL) {
6129 assert(!is_on_master_free_list(cur), "sanity");
6130 if (non_young) {
6131 if (cur->is_young()) {
6132 double end_sec = os::elapsedTime();
6133 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6134 non_young_time_ms += elapsed_ms;
6135
6136 start_sec = os::elapsedTime();
6137 non_young = false;
6138 }
6139 } else {
6140 if (!cur->is_young()) {
6141 double end_sec = os::elapsedTime();
6142 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6143 young_time_ms += elapsed_ms;
6144
6145 start_sec = os::elapsedTime();
6146 non_young = true;
6147 }
6148 }
6149
6150 rs_lengths += cur->rem_set()->occupied_locked();
6151
6152 HeapRegion* next = cur->next_in_collection_set();
6153 assert(cur->in_collection_set(), "bad CS");
6154 cur->set_next_in_collection_set(NULL);
6155 cur->set_in_collection_set(false);
6156
6157 if (cur->is_young()) {
6158 int index = cur->young_index_in_cset();
6159 assert(index != -1, "invariant");
6160 assert((uint) index < policy->young_cset_region_length(), "invariant");
6161 size_t words_survived = _surviving_young_words[index];
6162 cur->record_surv_words_in_group(words_survived);
6163
6164 // At this point the we have 'popped' cur from the collection set
6165 // (linked via next_in_collection_set()) but it is still in the
6166 // young list (linked via next_young_region()). Clear the
6167 // _next_young_region field.
6168 cur->set_next_young_region(NULL);
6169 } else {
6170 int index = cur->young_index_in_cset();
6171 assert(index == -1, "invariant");
6172 }
6173
6174 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6175 (!cur->is_young() && cur->young_index_in_cset() == -1),
6176 "invariant" );
6177
6178 if (!cur->evacuation_failed()) {
6179 MemRegion used_mr = cur->used_region();
6180
6181 // And the region is empty.
6182 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6183 pre_used += cur->used();
6184 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6185 } else {
6186 cur->uninstall_surv_rate_group();
6187 if (cur->is_young()) {
6188 cur->set_young_index_in_cset(-1);
6189 }
6190 cur->set_not_young();
6191 cur->set_evacuation_failed(false);
6192 // The region is now considered to be old.
6193 _old_set.add(cur);
6194 evacuation_info.increment_collectionset_used_after(cur->used());
6195 }
6196 cur = next;
6197 }
6198
6199 evacuation_info.set_regions_freed(local_free_list.length());
6200 policy->record_max_rs_lengths(rs_lengths);
6201 policy->cset_regions_freed();
6202
6203 double end_sec = os::elapsedTime();
6204 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6205
6206 if (non_young) {
6207 non_young_time_ms += elapsed_ms;
6208 } else {
6209 young_time_ms += elapsed_ms;
6210 }
6211
6212 prepend_to_freelist(&local_free_list);
6213 decrement_summary_bytes(pre_used);
6214 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6215 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6216 }
6217
6218 // This routine is similar to the above but does not record
6219 // any policy statistics or update free lists; we are abandoning
6220 // the current incremental collection set in preparation of a
6221 // full collection. After the full GC we will start to build up
6222 // the incremental collection set again.
6223 // This is only called when we're doing a full collection
6224 // and is immediately followed by the tearing down of the young list.
6225
6226 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6227 HeapRegion* cur = cs_head;
6228
6229 while (cur != NULL) {
6230 HeapRegion* next = cur->next_in_collection_set();
6231 assert(cur->in_collection_set(), "bad CS");
6232 cur->set_next_in_collection_set(NULL);
6233 cur->set_in_collection_set(false);
6234 cur->set_young_index_in_cset(-1);
6235 cur = next;
6236 }
6237 }
6238
6239 void G1CollectedHeap::set_free_regions_coming() {
6240 if (G1ConcRegionFreeingVerbose) {
6241 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6242 "setting free regions coming");
6243 }
6244
6245 assert(!free_regions_coming(), "pre-condition");
6246 _free_regions_coming = true;
6247 }
6248
6249 void G1CollectedHeap::reset_free_regions_coming() {
6250 assert(free_regions_coming(), "pre-condition");
6251
6252 {
6253 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6254 _free_regions_coming = false;
6255 SecondaryFreeList_lock->notify_all();
6256 }
6257
6258 if (G1ConcRegionFreeingVerbose) {
6259 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6260 "reset free regions coming");
6261 }
6262 }
6263
6264 void G1CollectedHeap::wait_while_free_regions_coming() {
6265 // Most of the time we won't have to wait, so let's do a quick test
6266 // first before we take the lock.
6267 if (!free_regions_coming()) {
6268 return;
6269 }
6270
6271 if (G1ConcRegionFreeingVerbose) {
6272 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6273 "waiting for free regions");
6274 }
6275
6276 {
6277 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6278 while (free_regions_coming()) {
6279 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6280 }
6281 }
6282
6283 if (G1ConcRegionFreeingVerbose) {
6284 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6285 "done waiting for free regions");
6286 }
6287 }
6288
6289 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6290 assert(heap_lock_held_for_gc(),
6291 "the heap lock should already be held by or for this thread");
6292 _young_list->push_region(hr);
6293 }
6294
6295 class NoYoungRegionsClosure: public HeapRegionClosure {
6296 private:
6297 bool _success;
6298 public:
6299 NoYoungRegionsClosure() : _success(true) { }
6300 bool doHeapRegion(HeapRegion* r) {
6301 if (r->is_young()) {
6302 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6303 r->bottom(), r->end());
6304 _success = false;
6305 }
6306 return false;
6307 }
6308 bool success() { return _success; }
6309 };
6310
6311 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6312 bool ret = _young_list->check_list_empty(check_sample);
6313
6314 if (check_heap) {
6315 NoYoungRegionsClosure closure;
6316 heap_region_iterate(&closure);
6317 ret = ret && closure.success();
6318 }
6319
6320 return ret;
6321 }
6322
6323 class TearDownRegionSetsClosure : public HeapRegionClosure {
6324 private:
6325 HeapRegionSet *_old_set;
6326
6327 public:
6328 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6329
6330 bool doHeapRegion(HeapRegion* r) {
6331 if (r->is_empty()) {
6332 // We ignore empty regions, we'll empty the free list afterwards
6333 } else if (r->is_young()) {
6334 // We ignore young regions, we'll empty the young list afterwards
6335 } else if (r->isHumongous()) {
6336 // We ignore humongous regions, we're not tearing down the
6337 // humongous region set
6338 } else {
6339 // The rest should be old
6340 _old_set->remove(r);
6341 }
6342 return false;
6343 }
6344
6345 ~TearDownRegionSetsClosure() {
6346 assert(_old_set->is_empty(), "post-condition");
6347 }
6348 };
6349
6350 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6351 assert_at_safepoint(true /* should_be_vm_thread */);
6352
6353 if (!free_list_only) {
6354 TearDownRegionSetsClosure cl(&_old_set);
6355 heap_region_iterate(&cl);
6356
6357 // Note that emptying the _young_list is postponed and instead done as
6358 // the first step when rebuilding the regions sets again. The reason for
6359 // this is that during a full GC string deduplication needs to know if
6360 // a collected region was young or old when the full GC was initiated.
6361 }
6362 _free_list.remove_all();
6363 }
6364
6365 class RebuildRegionSetsClosure : public HeapRegionClosure {
6366 private:
6367 bool _free_list_only;
6368 HeapRegionSet* _old_set;
6369 FreeRegionList* _free_list;
6370 size_t _total_used;
6371
6372 public:
6373 RebuildRegionSetsClosure(bool free_list_only,
6374 HeapRegionSet* old_set, FreeRegionList* free_list) :
6375 _free_list_only(free_list_only),
6376 _old_set(old_set), _free_list(free_list), _total_used(0) {
6377 assert(_free_list->is_empty(), "pre-condition");
6378 if (!free_list_only) {
6379 assert(_old_set->is_empty(), "pre-condition");
6380 }
6381 }
6382
6383 bool doHeapRegion(HeapRegion* r) {
6384 if (r->continuesHumongous()) {
6385 return false;
6386 }
6387
6388 if (r->is_empty()) {
6389 // Add free regions to the free list
6390 _free_list->add_as_tail(r);
6391 } else if (!_free_list_only) {
6392 assert(!r->is_young(), "we should not come across young regions");
6393
6394 if (r->isHumongous()) {
6395 // We ignore humongous regions, we left the humongous set unchanged
6396 } else {
6397 // The rest should be old, add them to the old set
6398 _old_set->add(r);
6399 }
6400 _total_used += r->used();
6401 }
6402
6403 return false;
6404 }
6405
6406 size_t total_used() {
6407 return _total_used;
6408 }
6409 };
6410
6411 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6412 assert_at_safepoint(true /* should_be_vm_thread */);
6413
6414 if (!free_list_only) {
6415 _young_list->empty_list();
6416 }
6417
6418 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6419 heap_region_iterate(&cl);
6420
6421 if (!free_list_only) {
6422 _summary_bytes_used = cl.total_used();
6423 }
6424 assert(_summary_bytes_used == recalculate_used(),
6425 err_msg("inconsistent _summary_bytes_used, "
6426 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6427 _summary_bytes_used, recalculate_used()));
6428 }
6429
6430 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6431 _refine_cte_cl->set_concurrent(concurrent);
6432 }
6433
6434 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6435 HeapRegion* hr = heap_region_containing(p);
6436 if (hr == NULL) {
6437 return false;
6438 } else {
6439 return hr->is_in(p);
6440 }
6441 }
6442
6443 // Methods for the mutator alloc region
6444
6445 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6446 bool force) {
6447 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6448 assert(!force || g1_policy()->can_expand_young_list(),
6449 "if force is true we should be able to expand the young list");
6450 bool young_list_full = g1_policy()->is_young_list_full();
6451 if (force || !young_list_full) {
6452 HeapRegion* new_alloc_region = new_region(word_size,
6453 false /* is_old */,
6454 false /* do_expand */);
6455 if (new_alloc_region != NULL) {
6456 set_region_short_lived_locked(new_alloc_region);
6457 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6458 return new_alloc_region;
6459 }
6460 }
6461 return NULL;
6462 }
6463
6464 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6465 size_t allocated_bytes) {
6466 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6467 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6468
6469 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6470 _summary_bytes_used += allocated_bytes;
6471 _hr_printer.retire(alloc_region);
6472 // We update the eden sizes here, when the region is retired,
6473 // instead of when it's allocated, since this is the point that its
6474 // used space has been recored in _summary_bytes_used.
6475 g1mm()->update_eden_size();
6476 }
6477
6478 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6479 bool force) {
6480 return _g1h->new_mutator_alloc_region(word_size, force);
6481 }
6482
6483 void G1CollectedHeap::set_par_threads() {
6484 // Don't change the number of workers. Use the value previously set
6485 // in the workgroup.
6486 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6487 uint n_workers = workers()->active_workers();
6488 assert(UseDynamicNumberOfGCThreads ||
6489 n_workers == workers()->total_workers(),
6490 "Otherwise should be using the total number of workers");
6491 if (n_workers == 0) {
6492 assert(false, "Should have been set in prior evacuation pause.");
6493 n_workers = ParallelGCThreads;
6494 workers()->set_active_workers(n_workers);
6495 }
6496 set_par_threads(n_workers);
6497 }
6498
6499 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6500 size_t allocated_bytes) {
6501 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6502 }
6503
6504 // Methods for the GC alloc regions
6505
6506 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6507 uint count,
6508 GCAllocPurpose ap) {
6509 assert(FreeList_lock->owned_by_self(), "pre-condition");
6510
6511 if (count < g1_policy()->max_regions(ap)) {
6512 bool survivor = (ap == GCAllocForSurvived);
6513 HeapRegion* new_alloc_region = new_region(word_size,
6514 !survivor,
6515 true /* do_expand */);
6516 if (new_alloc_region != NULL) {
6517 // We really only need to do this for old regions given that we
6518 // should never scan survivors. But it doesn't hurt to do it
6519 // for survivors too.
6520 new_alloc_region->set_saved_mark();
6521 if (survivor) {
6522 new_alloc_region->set_survivor();
6523 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6524 } else {
6525 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6526 }
6527 bool during_im = g1_policy()->during_initial_mark_pause();
6528 new_alloc_region->note_start_of_copying(during_im);
6529 return new_alloc_region;
6530 } else {
6531 g1_policy()->note_alloc_region_limit_reached(ap);
6532 }
6533 }
6534 return NULL;
6535 }
6536
6537 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6538 size_t allocated_bytes,
6539 GCAllocPurpose ap) {
6540 bool during_im = g1_policy()->during_initial_mark_pause();
6541 alloc_region->note_end_of_copying(during_im);
6542 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6543 if (ap == GCAllocForSurvived) {
6544 young_list()->add_survivor_region(alloc_region);
6545 } else {
6546 _old_set.add(alloc_region);
6547 }
6548 _hr_printer.retire(alloc_region);
6549 }
6550
6551 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6552 bool force) {
6553 assert(!force, "not supported for GC alloc regions");
6554 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6555 }
6556
6557 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6558 size_t allocated_bytes) {
6559 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6560 GCAllocForSurvived);
6561 }
6562
6563 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6564 bool force) {
6565 assert(!force, "not supported for GC alloc regions");
6566 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6567 }
6568
6569 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6570 size_t allocated_bytes) {
6571 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6572 GCAllocForTenured);
6573 }
6574 // Heap region set verification
6575
6576 class VerifyRegionListsClosure : public HeapRegionClosure {
6577 private:
6578 HeapRegionSet* _old_set;
6579 HeapRegionSet* _humongous_set;
6580 FreeRegionList* _free_list;
6581
6582 public:
6583 HeapRegionSetCount _old_count;
6584 HeapRegionSetCount _humongous_count;
6585 HeapRegionSetCount _free_count;
6586
6587 VerifyRegionListsClosure(HeapRegionSet* old_set,
6588 HeapRegionSet* humongous_set,
6589 FreeRegionList* free_list) :
6590 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6591 _old_count(), _humongous_count(), _free_count(){ }
6592
6593 bool doHeapRegion(HeapRegion* hr) {
6594 if (hr->continuesHumongous()) {
6595 return false;
6596 }
6597
6598 if (hr->is_young()) {
6599 // TODO
6600 } else if (hr->startsHumongous()) {
6601 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num()));
6602 _humongous_count.increment(1u, hr->capacity());
6603 } else if (hr->is_empty()) {
6604 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num()));
6605 _free_count.increment(1u, hr->capacity());
6606 } else {
6607 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num()));
6608 _old_count.increment(1u, hr->capacity());
6609 }
6610 return false;
6611 }
6612
6613 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6614 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6615 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6616 old_set->total_capacity_bytes(), _old_count.capacity()));
6617
6618 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6619 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6620 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6621
6622 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6623 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6624 free_list->total_capacity_bytes(), _free_count.capacity()));
6625 }
6626 };
6627
6628 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6629 HeapWord* bottom) {
6630 HeapWord* end = bottom + HeapRegion::GrainWords;
6631 MemRegion mr(bottom, end);
6632 assert(_g1_reserved.contains(mr), "invariant");
6633 // This might return NULL if the allocation fails
6634 return new HeapRegion(hrs_index, _bot_shared, mr);
6635 }
6636
6637 void G1CollectedHeap::verify_region_sets() {
6638 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6639
6640 // First, check the explicit lists.
6641 _free_list.verify_list();
6642 {
6643 // Given that a concurrent operation might be adding regions to
6644 // the secondary free list we have to take the lock before
6645 // verifying it.
6646 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6647 _secondary_free_list.verify_list();
6648 }
6649
6650 // If a concurrent region freeing operation is in progress it will
6651 // be difficult to correctly attributed any free regions we come
6652 // across to the correct free list given that they might belong to
6653 // one of several (free_list, secondary_free_list, any local lists,
6654 // etc.). So, if that's the case we will skip the rest of the
6655 // verification operation. Alternatively, waiting for the concurrent
6656 // operation to complete will have a non-trivial effect on the GC's
6657 // operation (no concurrent operation will last longer than the
6658 // interval between two calls to verification) and it might hide
6659 // any issues that we would like to catch during testing.
6660 if (free_regions_coming()) {
6661 return;
6662 }
6663
6664 // Make sure we append the secondary_free_list on the free_list so
6665 // that all free regions we will come across can be safely
6666 // attributed to the free_list.
6667 append_secondary_free_list_if_not_empty_with_lock();
6668
6669 // Finally, make sure that the region accounting in the lists is
6670 // consistent with what we see in the heap.
6671
6672 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6673 heap_region_iterate(&cl);
6674 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6675 }
6676
6677 // Optimized nmethod scanning
6678
6679 class RegisterNMethodOopClosure: public OopClosure {
6680 G1CollectedHeap* _g1h;
6681 nmethod* _nm;
6682
6683 template <class T> void do_oop_work(T* p) {
6684 T heap_oop = oopDesc::load_heap_oop(p);
6685 if (!oopDesc::is_null(heap_oop)) {
6686 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6687 HeapRegion* hr = _g1h->heap_region_containing(obj);
6688 assert(!hr->continuesHumongous(),
6689 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6690 " starting at "HR_FORMAT,
6691 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6692
6693 // HeapRegion::add_strong_code_root() avoids adding duplicate
6694 // entries but having duplicates is OK since we "mark" nmethods
6695 // as visited when we scan the strong code root lists during the GC.
6696 hr->add_strong_code_root(_nm);
6697 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6698 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6699 _nm, HR_FORMAT_PARAMS(hr)));
6700 }
6701 }
6702
6703 public:
6704 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6705 _g1h(g1h), _nm(nm) {}
6706
6707 void do_oop(oop* p) { do_oop_work(p); }
6708 void do_oop(narrowOop* p) { do_oop_work(p); }
6709 };
6710
6711 class UnregisterNMethodOopClosure: public OopClosure {
6712 G1CollectedHeap* _g1h;
6713 nmethod* _nm;
6714
6715 template <class T> void do_oop_work(T* p) {
6716 T heap_oop = oopDesc::load_heap_oop(p);
6717 if (!oopDesc::is_null(heap_oop)) {
6718 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6719 HeapRegion* hr = _g1h->heap_region_containing(obj);
6720 assert(!hr->continuesHumongous(),
6721 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6722 " starting at "HR_FORMAT,
6723 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6724
6725 hr->remove_strong_code_root(_nm);
6726 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6727 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6728 _nm, HR_FORMAT_PARAMS(hr)));
6729 }
6730 }
6731
6732 public:
6733 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6734 _g1h(g1h), _nm(nm) {}
6735
6736 void do_oop(oop* p) { do_oop_work(p); }
6737 void do_oop(narrowOop* p) { do_oop_work(p); }
6738 };
6739
6740 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6741 CollectedHeap::register_nmethod(nm);
6742
6743 guarantee(nm != NULL, "sanity");
6744 RegisterNMethodOopClosure reg_cl(this, nm);
6745 nm->oops_do(®_cl);
6746 }
6747
6748 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6749 CollectedHeap::unregister_nmethod(nm);
6750
6751 guarantee(nm != NULL, "sanity");
6752 UnregisterNMethodOopClosure reg_cl(this, nm);
6753 nm->oops_do(®_cl, true);
6754 }
6755
6756 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6757 public:
6758 bool doHeapRegion(HeapRegion *hr) {
6759 assert(!hr->isHumongous(),
6760 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6761 HR_FORMAT_PARAMS(hr)));
6762 hr->migrate_strong_code_roots();
6763 return false;
6764 }
6765 };
6766
6767 void G1CollectedHeap::migrate_strong_code_roots() {
6768 MigrateCodeRootsHeapRegionClosure cl;
6769 double migrate_start = os::elapsedTime();
6770 collection_set_iterate(&cl);
6771 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6772 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6773 }
6774
6775 void G1CollectedHeap::purge_code_root_memory() {
6776 double purge_start = os::elapsedTime();
6777 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6778 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6779 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6780 }
6781
6782 // Mark all the code roots that point into regions *not* in the
6783 // collection set.
6784 //
6785 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6786 // walking the the code roots lists of regions not in the collection
6787 // set. Suppose we have an nmethod (M) that points to objects in two
6788 // separate regions - one in the collection set (R1) and one not (R2).
6789 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6790 // nmethod M when walking the code roots for R1. When we come to scan
6791 // the code roots for R2, we would see that M is already marked and it
6792 // would be skipped and the objects in R2 that are referenced from M
6793 // would not be evacuated.
6794
6795 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6796
6797 class MarkStrongCodeRootOopClosure: public OopClosure {
6798 ConcurrentMark* _cm;
6799 HeapRegion* _hr;
6800 uint _worker_id;
6801
6802 template <class T> void do_oop_work(T* p) {
6803 T heap_oop = oopDesc::load_heap_oop(p);
6804 if (!oopDesc::is_null(heap_oop)) {
6805 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6806 // Only mark objects in the region (which is assumed
6807 // to be not in the collection set).
6808 if (_hr->is_in(obj)) {
6809 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6810 }
6811 }
6812 }
6813
6814 public:
6815 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6816 _cm(cm), _hr(hr), _worker_id(worker_id) {
6817 assert(!_hr->in_collection_set(), "sanity");
6818 }
6819
6820 void do_oop(narrowOop* p) { do_oop_work(p); }
6821 void do_oop(oop* p) { do_oop_work(p); }
6822 };
6823
6824 MarkStrongCodeRootOopClosure _oop_cl;
6825
6826 public:
6827 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6828 _oop_cl(cm, hr, worker_id) {}
6829
6830 void do_code_blob(CodeBlob* cb) {
6831 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6832 if (nm != NULL) {
6833 nm->oops_do(&_oop_cl);
6834 }
6835 }
6836 };
6837
6838 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6839 G1CollectedHeap* _g1h;
6840 uint _worker_id;
6841
6842 public:
6843 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6844 _g1h(g1h), _worker_id(worker_id) {}
6845
6846 bool doHeapRegion(HeapRegion *hr) {
6847 HeapRegionRemSet* hrrs = hr->rem_set();
6848 if (hr->continuesHumongous()) {
6849 // Code roots should never be attached to a continuation of a humongous region
6850 assert(hrrs->strong_code_roots_list_length() == 0,
6851 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6852 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6853 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6854 hrrs->strong_code_roots_list_length()));
6855 return false;
6856 }
6857
6858 if (hr->in_collection_set()) {
6859 // Don't mark code roots into regions in the collection set here.
6860 // They will be marked when we scan them.
6861 return false;
6862 }
6863
6864 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6865 hr->strong_code_roots_do(&cb_cl);
6866 return false;
6867 }
6868 };
6869
6870 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6871 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6872 if (G1CollectedHeap::use_parallel_gc_threads()) {
6873 heap_region_par_iterate_chunked(&cl,
6874 worker_id,
6875 workers()->active_workers(),
6876 HeapRegion::ParMarkRootClaimValue);
6877 } else {
6878 heap_region_iterate(&cl);
6879 }
6880 }
6881
6882 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6883 G1CollectedHeap* _g1h;
6884
6885 public:
6886 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6887 _g1h(g1h) {}
6888
6889 void do_code_blob(CodeBlob* cb) {
6890 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6891 if (nm == NULL) {
6892 return;
6893 }
6894
6895 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6896 _g1h->register_nmethod(nm);
6897 }
6898 }
6899 };
6900
6901 void G1CollectedHeap::rebuild_strong_code_roots() {
6902 RebuildStrongCodeRootClosure blob_cl(this);
6903 CodeCache::blobs_do(&blob_cl);
6904 }