1 /*
2 * Copyright (c) 2001, 2013, 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/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
35 #include "gc_implementation/g1/g1EvacFailure.hpp"
36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
37 #include "gc_implementation/g1/g1Log.hpp"
38 #include "gc_implementation/g1/g1MarkSweep.hpp"
39 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
40 #include "gc_implementation/g1/g1RemSet.inline.hpp"
41 #include "gc_implementation/g1/g1YCTypes.hpp"
42 #include "gc_implementation/g1/heapRegion.inline.hpp"
43 #include "gc_implementation/g1/heapRegionRemSet.hpp"
44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
45 #include "gc_implementation/g1/vm_operations_g1.hpp"
46 #include "gc_implementation/shared/gcHeapSummary.hpp"
47 #include "gc_implementation/shared/gcTimer.hpp"
48 #include "gc_implementation/shared/gcTrace.hpp"
49 #include "gc_implementation/shared/gcTraceTime.hpp"
50 #include "gc_implementation/shared/isGCActiveMark.hpp"
51 #include "memory/gcLocker.inline.hpp"
52 #include "memory/genOopClosures.inline.hpp"
53 #include "memory/generationSpec.hpp"
54 #include "memory/referenceProcessor.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "oops/oop.pcgc.inline.hpp"
57 #include "runtime/aprofiler.hpp"
58 #include "runtime/vmThread.hpp"
59
60 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
61
62 // turn it on so that the contents of the young list (scan-only /
63 // to-be-collected) are printed at "strategic" points before / during
64 // / after the collection --- this is useful for debugging
65 #define YOUNG_LIST_VERBOSE 0
66 // CURRENT STATUS
67 // This file is under construction. Search for "FIXME".
68
69 // INVARIANTS/NOTES
70 //
71 // All allocation activity covered by the G1CollectedHeap interface is
72 // serialized by acquiring the HeapLock. This happens in mem_allocate
73 // and allocate_new_tlab, which are the "entry" points to the
74 // allocation code from the rest of the JVM. (Note that this does not
75 // apply to TLAB allocation, which is not part of this interface: it
76 // is done by clients of this interface.)
77
78 // Notes on implementation of parallelism in different tasks.
79 //
80 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
81 // The number of GC workers is passed to heap_region_par_iterate_chunked().
82 // It does use run_task() which sets _n_workers in the task.
83 // G1ParTask executes g1_process_strong_roots() ->
84 // SharedHeap::process_strong_roots() which calls eventually to
85 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
86 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
87 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
88 //
89
90 // Local to this file.
91
92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
93 SuspendibleThreadSet* _sts;
94 G1RemSet* _g1rs;
95 ConcurrentG1Refine* _cg1r;
96 bool _concurrent;
97 public:
98 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
99 G1RemSet* g1rs,
100 ConcurrentG1Refine* cg1r) :
101 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
102 {}
103 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
104 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
105 // This path is executed by the concurrent refine or mutator threads,
106 // concurrently, and so we do not care if card_ptr contains references
107 // that point into the collection set.
108 assert(!oops_into_cset, "should be");
109
110 if (_concurrent && _sts->should_yield()) {
111 // Caller will actually yield.
112 return false;
113 }
114 // Otherwise, we finished successfully; return true.
115 return true;
116 }
117 void set_concurrent(bool b) { _concurrent = b; }
118 };
119
120
121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
122 int _calls;
123 G1CollectedHeap* _g1h;
124 CardTableModRefBS* _ctbs;
125 int _histo[256];
126 public:
127 ClearLoggedCardTableEntryClosure() :
128 _calls(0)
129 {
130 _g1h = G1CollectedHeap::heap();
131 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
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)
162 {
163 _g1h = G1CollectedHeap::heap();
164 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
165 }
166 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
167 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
168 _calls++;
169 *card_ptr = 0;
170 }
171 return true;
172 }
173 int calls() { return _calls; }
174 };
175
176 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
177 public:
178 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
179 *card_ptr = CardTableModRefBS::dirty_card_val();
180 return true;
181 }
182 };
183
184 YoungList::YoungList(G1CollectedHeap* g1h) :
185 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
186 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
187 guarantee(check_list_empty(false), "just making sure...");
188 }
189
190 void YoungList::push_region(HeapRegion *hr) {
191 assert(!hr->is_young(), "should not already be young");
192 assert(hr->get_next_young_region() == NULL, "cause it should!");
193
194 hr->set_next_young_region(_head);
195 _head = hr;
196
197 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
198 ++_length;
199 }
200
201 void YoungList::add_survivor_region(HeapRegion* hr) {
202 assert(hr->is_survivor(), "should be flagged as survivor region");
203 assert(hr->get_next_young_region() == NULL, "cause it should!");
204
205 hr->set_next_young_region(_survivor_head);
206 if (_survivor_head == NULL) {
207 _survivor_tail = hr;
208 }
209 _survivor_head = hr;
210 ++_survivor_length;
211 }
212
213 void YoungList::empty_list(HeapRegion* list) {
214 while (list != NULL) {
215 HeapRegion* next = list->get_next_young_region();
216 list->set_next_young_region(NULL);
217 list->uninstall_surv_rate_group();
218 list->set_not_young();
219 list = next;
220 }
221 }
222
223 void YoungList::empty_list() {
224 assert(check_list_well_formed(), "young list should be well formed");
225
226 empty_list(_head);
227 _head = NULL;
228 _length = 0;
229
230 empty_list(_survivor_head);
231 _survivor_head = NULL;
232 _survivor_tail = NULL;
233 _survivor_length = 0;
234
235 _last_sampled_rs_lengths = 0;
236
237 assert(check_list_empty(false), "just making sure...");
238 }
239
240 bool YoungList::check_list_well_formed() {
241 bool ret = true;
242
243 uint length = 0;
244 HeapRegion* curr = _head;
245 HeapRegion* last = NULL;
246 while (curr != NULL) {
247 if (!curr->is_young()) {
248 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
249 "incorrectly tagged (y: %d, surv: %d)",
250 curr->bottom(), curr->end(),
251 curr->is_young(), curr->is_survivor());
252 ret = false;
253 }
254 ++length;
255 last = curr;
256 curr = curr->get_next_young_region();
257 }
258 ret = ret && (length == _length);
259
260 if (!ret) {
261 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
262 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
263 length, _length);
264 }
265
266 return ret;
267 }
268
269 bool YoungList::check_list_empty(bool check_sample) {
270 bool ret = true;
271
272 if (_length != 0) {
273 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
274 _length);
275 ret = false;
276 }
277 if (check_sample && _last_sampled_rs_lengths != 0) {
278 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
279 ret = false;
280 }
281 if (_head != NULL) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
283 ret = false;
284 }
285 if (!ret) {
286 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
287 }
288
289 return ret;
290 }
291
292 void
293 YoungList::rs_length_sampling_init() {
294 _sampled_rs_lengths = 0;
295 _curr = _head;
296 }
297
298 bool
299 YoungList::rs_length_sampling_more() {
300 return _curr != NULL;
301 }
302
303 void
304 YoungList::rs_length_sampling_next() {
305 assert( _curr != NULL, "invariant" );
306 size_t rs_length = _curr->rem_set()->occupied();
307
308 _sampled_rs_lengths += rs_length;
309
310 // The current region may not yet have been added to the
311 // incremental collection set (it gets added when it is
312 // retired as the current allocation region).
313 if (_curr->in_collection_set()) {
314 // Update the collection set policy information for this region
315 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
316 }
317
318 _curr = _curr->get_next_young_region();
319 if (_curr == NULL) {
320 _last_sampled_rs_lengths = _sampled_rs_lengths;
321 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
322 }
323 }
324
325 void
326 YoungList::reset_auxilary_lists() {
327 guarantee( is_empty(), "young list should be empty" );
328 assert(check_list_well_formed(), "young list should be well formed");
329
330 // Add survivor regions to SurvRateGroup.
331 _g1h->g1_policy()->note_start_adding_survivor_regions();
332 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
333
334 int young_index_in_cset = 0;
335 for (HeapRegion* curr = _survivor_head;
336 curr != NULL;
337 curr = curr->get_next_young_region()) {
338 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
339
340 // The region is a non-empty survivor so let's add it to
341 // the incremental collection set for the next evacuation
342 // pause.
343 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
344 young_index_in_cset += 1;
345 }
346 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
347 _g1h->g1_policy()->note_stop_adding_survivor_regions();
348
349 _head = _survivor_head;
350 _length = _survivor_length;
351 if (_survivor_head != NULL) {
352 assert(_survivor_tail != NULL, "cause it shouldn't be");
353 assert(_survivor_length > 0, "invariant");
354 _survivor_tail->set_next_young_region(NULL);
355 }
356
357 // Don't clear the survivor list handles until the start of
358 // the next evacuation pause - we need it in order to re-tag
359 // the survivor regions from this evacuation pause as 'young'
360 // at the start of the next.
361
362 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
363
364 assert(check_list_well_formed(), "young list should be well formed");
365 }
366
367 void YoungList::print() {
368 HeapRegion* lists[] = {_head, _survivor_head};
369 const char* names[] = {"YOUNG", "SURVIVOR"};
370
371 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
372 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
373 HeapRegion *curr = lists[list];
374 if (curr == NULL)
375 gclog_or_tty->print_cr(" empty");
376 while (curr != NULL) {
377 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
378 HR_FORMAT_PARAMS(curr),
379 curr->prev_top_at_mark_start(),
380 curr->next_top_at_mark_start(),
381 curr->age_in_surv_rate_group_cond());
382 curr = curr->get_next_young_region();
383 }
384 }
385
386 gclog_or_tty->print_cr("");
387 }
388
389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
390 {
391 // Claim the right to put the region on the dirty cards region list
392 // by installing a self pointer.
393 HeapRegion* next = hr->get_next_dirty_cards_region();
394 if (next == NULL) {
395 HeapRegion* res = (HeapRegion*)
396 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
397 NULL);
398 if (res == NULL) {
399 HeapRegion* head;
400 do {
401 // Put the region to the dirty cards region list.
402 head = _dirty_cards_region_list;
403 next = (HeapRegion*)
404 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
405 if (next == head) {
406 assert(hr->get_next_dirty_cards_region() == hr,
407 "hr->get_next_dirty_cards_region() != hr");
408 if (next == NULL) {
409 // The last region in the list points to itself.
410 hr->set_next_dirty_cards_region(hr);
411 } else {
412 hr->set_next_dirty_cards_region(next);
413 }
414 }
415 } while (next != head);
416 }
417 }
418 }
419
420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
421 {
422 HeapRegion* head;
423 HeapRegion* hr;
424 do {
425 head = _dirty_cards_region_list;
426 if (head == NULL) {
427 return NULL;
428 }
429 HeapRegion* new_head = head->get_next_dirty_cards_region();
430 if (head == new_head) {
431 // The last region.
432 new_head = NULL;
433 }
434 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
435 head);
436 } while (hr != head);
437 assert(hr != NULL, "invariant");
438 hr->set_next_dirty_cards_region(NULL);
439 return hr;
440 }
441
442 void G1CollectedHeap::stop_conc_gc_threads() {
443 _cg1r->stop();
444 _cmThread->stop();
445 }
446
447 #ifdef ASSERT
448 // A region is added to the collection set as it is retired
449 // so an address p can point to a region which will be in the
450 // collection set but has not yet been retired. This method
451 // therefore is only accurate during a GC pause after all
452 // regions have been retired. It is used for debugging
453 // to check if an nmethod has references to objects that can
454 // be move during a partial collection. Though it can be
455 // inaccurate, it is sufficient for G1 because the conservative
456 // implementation of is_scavengable() for G1 will indicate that
457 // all nmethods must be scanned during a partial collection.
458 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
459 HeapRegion* hr = heap_region_containing(p);
460 return hr != NULL && hr->in_collection_set();
461 }
462 #endif
463
464 // Returns true if the reference points to an object that
465 // can move in an incremental collection.
466 bool G1CollectedHeap::is_scavengable(const void* p) {
467 G1CollectedHeap* g1h = G1CollectedHeap::heap();
468 G1CollectorPolicy* g1p = g1h->g1_policy();
469 HeapRegion* hr = heap_region_containing(p);
470 if (hr == NULL) {
471 // perm gen (or null)
472 return false;
473 } else {
474 return !hr->isHumongous();
475 }
476 }
477
478 void G1CollectedHeap::check_ct_logs_at_safepoint() {
479 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
480 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
481
482 // Count the dirty cards at the start.
483 CountNonCleanMemRegionClosure count1(this);
484 ct_bs->mod_card_iterate(&count1);
485 int orig_count = count1.n();
486
487 // First clear the logged cards.
488 ClearLoggedCardTableEntryClosure clear;
489 dcqs.set_closure(&clear);
490 dcqs.apply_closure_to_all_completed_buffers();
491 dcqs.iterate_closure_all_threads(false);
492 clear.print_histo();
493
494 // Now ensure that there's no dirty cards.
495 CountNonCleanMemRegionClosure count2(this);
496 ct_bs->mod_card_iterate(&count2);
497 if (count2.n() != 0) {
498 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
499 count2.n(), orig_count);
500 }
501 guarantee(count2.n() == 0, "Card table should be clean.");
502
503 RedirtyLoggedCardTableEntryClosure redirty;
504 JavaThread::dirty_card_queue_set().set_closure(&redirty);
505 dcqs.apply_closure_to_all_completed_buffers();
506 dcqs.iterate_closure_all_threads(false);
507 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
508 clear.calls(), orig_count);
509 guarantee(redirty.calls() == clear.calls(),
510 "Or else mechanism is broken.");
511
512 CountNonCleanMemRegionClosure count3(this);
513 ct_bs->mod_card_iterate(&count3);
514 if (count3.n() != orig_count) {
515 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
516 orig_count, count3.n());
517 guarantee(count3.n() >= orig_count, "Should have restored them all.");
518 }
519
520 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
521 }
522
523 // Private class members.
524
525 G1CollectedHeap* G1CollectedHeap::_g1h;
526
527 // Private methods.
528
529 HeapRegion*
530 G1CollectedHeap::new_region_try_secondary_free_list() {
531 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
532 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
533 if (!_secondary_free_list.is_empty()) {
534 if (G1ConcRegionFreeingVerbose) {
535 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
536 "secondary_free_list has %u entries",
537 _secondary_free_list.length());
538 }
539 // It looks as if there are free regions available on the
540 // secondary_free_list. Let's move them to the free_list and try
541 // again to allocate from it.
542 append_secondary_free_list();
543
544 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
545 "empty we should have moved at least one entry to the free_list");
546 HeapRegion* res = _free_list.remove_head();
547 if (G1ConcRegionFreeingVerbose) {
548 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
549 "allocated "HR_FORMAT" from secondary_free_list",
550 HR_FORMAT_PARAMS(res));
551 }
552 return res;
553 }
554
555 // Wait here until we get notified either when (a) there are no
556 // more free regions coming or (b) some regions have been moved on
557 // the secondary_free_list.
558 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
559 }
560
561 if (G1ConcRegionFreeingVerbose) {
562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
563 "could not allocate from secondary_free_list");
564 }
565 return NULL;
566 }
567
568 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
569 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
570 "the only time we use this to allocate a humongous region is "
571 "when we are allocating a single humongous region");
572
573 HeapRegion* res;
574 if (G1StressConcRegionFreeing) {
575 if (!_secondary_free_list.is_empty()) {
576 if (G1ConcRegionFreeingVerbose) {
577 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
578 "forced to look at the secondary_free_list");
579 }
580 res = new_region_try_secondary_free_list();
581 if (res != NULL) {
582 return res;
583 }
584 }
585 }
586 res = _free_list.remove_head_or_null();
587 if (res == NULL) {
588 if (G1ConcRegionFreeingVerbose) {
589 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
590 "res == NULL, trying the secondary_free_list");
591 }
592 res = new_region_try_secondary_free_list();
593 }
594 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
595 // Currently, only attempts to allocate GC alloc regions set
596 // do_expand to true. So, we should only reach here during a
597 // safepoint. If this assumption changes we might have to
598 // reconsider the use of _expand_heap_after_alloc_failure.
599 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
600
601 ergo_verbose1(ErgoHeapSizing,
602 "attempt heap expansion",
603 ergo_format_reason("region allocation request failed")
604 ergo_format_byte("allocation request"),
605 word_size * HeapWordSize);
606 if (expand(word_size * HeapWordSize)) {
607 // Given that expand() succeeded in expanding the heap, and we
608 // always expand the heap by an amount aligned to the heap
609 // region size, the free list should in theory not be empty. So
610 // it would probably be OK to use remove_head(). But the extra
611 // check for NULL is unlikely to be a performance issue here (we
612 // just expanded the heap!) so let's just be conservative and
613 // use remove_head_or_null().
614 res = _free_list.remove_head_or_null();
615 } else {
616 _expand_heap_after_alloc_failure = false;
617 }
618 }
619 return res;
620 }
621
622 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
623 size_t word_size) {
624 assert(isHumongous(word_size), "word_size should be humongous");
625 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
626
627 uint first = G1_NULL_HRS_INDEX;
628 if (num_regions == 1) {
629 // Only one region to allocate, no need to go through the slower
630 // path. The caller will attempt the expansion if this fails, so
631 // let's not try to expand here too.
632 HeapRegion* hr = new_region(word_size, false /* do_expand */);
633 if (hr != NULL) {
634 first = hr->hrs_index();
635 } else {
636 first = G1_NULL_HRS_INDEX;
637 }
638 } else {
639 // We can't allocate humongous regions while cleanupComplete() is
640 // running, since some of the regions we find to be empty might not
641 // yet be added to the free list and it is not straightforward to
642 // know which list they are on so that we can remove them. Note
643 // that we only need to do this if we need to allocate more than
644 // one region to satisfy the current humongous allocation
645 // request. If we are only allocating one region we use the common
646 // region allocation code (see above).
647 wait_while_free_regions_coming();
648 append_secondary_free_list_if_not_empty_with_lock();
649
650 if (free_regions() >= num_regions) {
651 first = _hrs.find_contiguous(num_regions);
652 if (first != G1_NULL_HRS_INDEX) {
653 for (uint i = first; i < first + num_regions; ++i) {
654 HeapRegion* hr = region_at(i);
655 assert(hr->is_empty(), "sanity");
656 assert(is_on_master_free_list(hr), "sanity");
657 hr->set_pending_removal(true);
658 }
659 _free_list.remove_all_pending(num_regions);
660 }
661 }
662 }
663 return first;
664 }
665
666 HeapWord*
667 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
668 uint num_regions,
669 size_t word_size) {
670 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
671 assert(isHumongous(word_size), "word_size should be humongous");
672 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
673
674 // Index of last region in the series + 1.
675 uint last = first + num_regions;
676
677 // We need to initialize the region(s) we just discovered. This is
678 // a bit tricky given that it can happen concurrently with
679 // refinement threads refining cards on these regions and
680 // potentially wanting to refine the BOT as they are scanning
681 // those cards (this can happen shortly after a cleanup; see CR
682 // 6991377). So we have to set up the region(s) carefully and in
683 // a specific order.
684
685 // The word size sum of all the regions we will allocate.
686 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
687 assert(word_size <= word_size_sum, "sanity");
688
689 // This will be the "starts humongous" region.
690 HeapRegion* first_hr = region_at(first);
691 // The header of the new object will be placed at the bottom of
692 // the first region.
693 HeapWord* new_obj = first_hr->bottom();
694 // This will be the new end of the first region in the series that
695 // should also match the end of the last region in the series.
696 HeapWord* new_end = new_obj + word_size_sum;
697 // This will be the new top of the first region that will reflect
698 // this allocation.
699 HeapWord* new_top = new_obj + word_size;
700
701 // First, we need to zero the header of the space that we will be
702 // allocating. When we update top further down, some refinement
703 // threads might try to scan the region. By zeroing the header we
704 // ensure that any thread that will try to scan the region will
705 // come across the zero klass word and bail out.
706 //
707 // NOTE: It would not have been correct to have used
708 // CollectedHeap::fill_with_object() and make the space look like
709 // an int array. The thread that is doing the allocation will
710 // later update the object header to a potentially different array
711 // type and, for a very short period of time, the klass and length
712 // fields will be inconsistent. This could cause a refinement
713 // thread to calculate the object size incorrectly.
714 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
715
716 // We will set up the first region as "starts humongous". This
717 // will also update the BOT covering all the regions to reflect
718 // that there is a single object that starts at the bottom of the
719 // first region.
720 first_hr->set_startsHumongous(new_top, new_end);
721
722 // Then, if there are any, we will set up the "continues
723 // humongous" regions.
724 HeapRegion* hr = NULL;
725 for (uint i = first + 1; i < last; ++i) {
726 hr = region_at(i);
727 hr->set_continuesHumongous(first_hr);
728 }
729 // If we have "continues humongous" regions (hr != NULL), then the
730 // end of the last one should match new_end.
731 assert(hr == NULL || hr->end() == new_end, "sanity");
732
733 // Up to this point no concurrent thread would have been able to
734 // do any scanning on any region in this series. All the top
735 // fields still point to bottom, so the intersection between
736 // [bottom,top] and [card_start,card_end] will be empty. Before we
737 // update the top fields, we'll do a storestore to make sure that
738 // no thread sees the update to top before the zeroing of the
739 // object header and the BOT initialization.
740 OrderAccess::storestore();
741
742 // Now that the BOT and the object header have been initialized,
743 // we can update top of the "starts humongous" region.
744 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
745 "new_top should be in this region");
746 first_hr->set_top(new_top);
747 if (_hr_printer.is_active()) {
748 HeapWord* bottom = first_hr->bottom();
749 HeapWord* end = first_hr->orig_end();
750 if ((first + 1) == last) {
751 // the series has a single humongous region
752 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
753 } else {
754 // the series has more than one humongous regions
755 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
756 }
757 }
758
759 // Now, we will update the top fields of the "continues humongous"
760 // regions. The reason we need to do this is that, otherwise,
761 // these regions would look empty and this will confuse parts of
762 // G1. For example, the code that looks for a consecutive number
763 // of empty regions will consider them empty and try to
764 // re-allocate them. We can extend is_empty() to also include
765 // !continuesHumongous(), but it is easier to just update the top
766 // fields here. The way we set top for all regions (i.e., top ==
767 // end for all regions but the last one, top == new_top for the
768 // last one) is actually used when we will free up the humongous
769 // region in free_humongous_region().
770 hr = NULL;
771 for (uint i = first + 1; i < last; ++i) {
772 hr = region_at(i);
773 if ((i + 1) == last) {
774 // last continues humongous region
775 assert(hr->bottom() < new_top && new_top <= hr->end(),
776 "new_top should fall on this region");
777 hr->set_top(new_top);
778 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
779 } else {
780 // not last one
781 assert(new_top > hr->end(), "new_top should be above this region");
782 hr->set_top(hr->end());
783 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
784 }
785 }
786 // If we have continues humongous regions (hr != NULL), then the
787 // end of the last one should match new_end and its top should
788 // match new_top.
789 assert(hr == NULL ||
790 (hr->end() == new_end && hr->top() == new_top), "sanity");
791
792 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
793 _summary_bytes_used += first_hr->used();
794 _humongous_set.add(first_hr);
795
796 return new_obj;
797 }
798
799 // If could fit into free regions w/o expansion, try.
800 // Otherwise, if can expand, do so.
801 // Otherwise, if using ex regions might help, try with ex given back.
802 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
803 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
804
805 verify_region_sets_optional();
806
807 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
808 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
809 uint x_num = expansion_regions();
810 uint fs = _hrs.free_suffix();
811 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
812 if (first == G1_NULL_HRS_INDEX) {
813 // The only thing we can do now is attempt expansion.
814 if (fs + x_num >= num_regions) {
815 // If the number of regions we're trying to allocate for this
816 // object is at most the number of regions in the free suffix,
817 // then the call to humongous_obj_allocate_find_first() above
818 // should have succeeded and we wouldn't be here.
819 //
820 // We should only be trying to expand when the free suffix is
821 // not sufficient for the object _and_ we have some expansion
822 // room available.
823 assert(num_regions > fs, "earlier allocation should have succeeded");
824
825 ergo_verbose1(ErgoHeapSizing,
826 "attempt heap expansion",
827 ergo_format_reason("humongous allocation request failed")
828 ergo_format_byte("allocation request"),
829 word_size * HeapWordSize);
830 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
831 // Even though the heap was expanded, it might not have
832 // reached the desired size. So, we cannot assume that the
833 // allocation will succeed.
834 first = humongous_obj_allocate_find_first(num_regions, word_size);
835 }
836 }
837 }
838
839 HeapWord* result = NULL;
840 if (first != G1_NULL_HRS_INDEX) {
841 result =
842 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
843 assert(result != NULL, "it should always return a valid result");
844
845 // A successful humongous object allocation changes the used space
846 // information of the old generation so we need to recalculate the
847 // sizes and update the jstat counters here.
848 g1mm()->update_sizes();
849 }
850
851 verify_region_sets_optional();
852
853 return result;
854 }
855
856 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
857 assert_heap_not_locked_and_not_at_safepoint();
858 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
859
860 unsigned int dummy_gc_count_before;
861 return attempt_allocation(word_size, &dummy_gc_count_before);
862 }
863
864 HeapWord*
865 G1CollectedHeap::mem_allocate(size_t word_size,
866 bool* gc_overhead_limit_was_exceeded) {
867 assert_heap_not_locked_and_not_at_safepoint();
868
869 // Loop until the allocation is satisfied, or unsatisfied after GC.
870 for (int try_count = 1; /* we'll return */; try_count += 1) {
871 unsigned int gc_count_before;
872
873 HeapWord* result = NULL;
874 if (!isHumongous(word_size)) {
875 result = attempt_allocation(word_size, &gc_count_before);
876 } else {
877 result = attempt_allocation_humongous(word_size, &gc_count_before);
878 }
879 if (result != NULL) {
880 return result;
881 }
882
883 // Create the garbage collection operation...
884 VM_G1CollectForAllocation op(gc_count_before, word_size);
885 // ...and get the VM thread to execute it.
886 VMThread::execute(&op);
887
888 if (op.prologue_succeeded() && op.pause_succeeded()) {
889 // If the operation was successful we'll return the result even
890 // if it is NULL. If the allocation attempt failed immediately
891 // after a Full GC, it's unlikely we'll be able to allocate now.
892 HeapWord* result = op.result();
893 if (result != NULL && !isHumongous(word_size)) {
894 // Allocations that take place on VM operations do not do any
895 // card dirtying and we have to do it here. We only have to do
896 // this for non-humongous allocations, though.
897 dirty_young_block(result, word_size);
898 }
899 return result;
900 } else {
901 assert(op.result() == NULL,
902 "the result should be NULL if the VM op did not succeed");
903 }
904
905 // Give a warning if we seem to be looping forever.
906 if ((QueuedAllocationWarningCount > 0) &&
907 (try_count % QueuedAllocationWarningCount == 0)) {
908 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 return NULL;
914 }
915
916 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
917 unsigned int *gc_count_before_ret) {
918 // Make sure you read the note in attempt_allocation_humongous().
919
920 assert_heap_not_locked_and_not_at_safepoint();
921 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
922 "be called for humongous allocation requests");
923
924 // We should only get here after the first-level allocation attempt
925 // (attempt_allocation()) failed to allocate.
926
927 // We will loop until a) we manage to successfully perform the
928 // allocation or b) we successfully schedule a collection which
929 // fails to perform the allocation. b) is the only case when we'll
930 // return NULL.
931 HeapWord* result = NULL;
932 for (int try_count = 1; /* we'll return */; try_count += 1) {
933 bool should_try_gc;
934 unsigned int gc_count_before;
935
936 {
937 MutexLockerEx x(Heap_lock);
938
939 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
940 false /* bot_updates */);
941 if (result != NULL) {
942 return result;
943 }
944
945 // If we reach here, attempt_allocation_locked() above failed to
946 // allocate a new region. So the mutator alloc region should be NULL.
947 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
948
949 if (GC_locker::is_active_and_needs_gc()) {
950 if (g1_policy()->can_expand_young_list()) {
951 // No need for an ergo verbose message here,
952 // can_expand_young_list() does this when it returns true.
953 result = _mutator_alloc_region.attempt_allocation_force(word_size,
954 false /* bot_updates */);
955 if (result != NULL) {
956 return result;
957 }
958 }
959 should_try_gc = false;
960 } else {
961 // The GCLocker may not be active but the GCLocker initiated
962 // GC may not yet have been performed (GCLocker::needs_gc()
963 // returns true). In this case we do not try this GC and
964 // wait until the GCLocker initiated GC is performed, and
965 // then retry the allocation.
966 if (GC_locker::needs_gc()) {
967 should_try_gc = false;
968 } else {
969 // Read the GC count while still holding the Heap_lock.
970 gc_count_before = total_collections();
971 should_try_gc = true;
972 }
973 }
974 }
975
976 if (should_try_gc) {
977 bool succeeded;
978 result = do_collection_pause(word_size, gc_count_before, &succeeded);
979 if (result != NULL) {
980 assert(succeeded, "only way to get back a non-NULL result");
981 return result;
982 }
983
984 if (succeeded) {
985 // If we get here we successfully scheduled a collection which
986 // failed to allocate. No point in trying to allocate
987 // further. We'll just return NULL.
988 MutexLockerEx x(Heap_lock);
989 *gc_count_before_ret = total_collections();
990 return NULL;
991 }
992 } else {
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 }
998
999 // We can reach here if we were unsuccessful in scheduling a
1000 // collection (because another thread beat us to it) or if we were
1001 // stalled due to the GC locker. In either can we should retry the
1002 // allocation attempt in case another thread successfully
1003 // performed a collection and reclaimed enough space. We do the
1004 // first attempt (without holding the Heap_lock) here and the
1005 // follow-on attempt will be at the start of the next loop
1006 // iteration (after taking the Heap_lock).
1007 result = _mutator_alloc_region.attempt_allocation(word_size,
1008 false /* bot_updates */);
1009 if (result != NULL) {
1010 return result;
1011 }
1012
1013 // Give a warning if we seem to be looping forever.
1014 if ((QueuedAllocationWarningCount > 0) &&
1015 (try_count % QueuedAllocationWarningCount == 0)) {
1016 warning("G1CollectedHeap::attempt_allocation_slow() "
1017 "retries %d times", try_count);
1018 }
1019 }
1020
1021 ShouldNotReachHere();
1022 return NULL;
1023 }
1024
1025 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1026 unsigned int * gc_count_before_ret) {
1027 // The structure of this method has a lot of similarities to
1028 // attempt_allocation_slow(). The reason these two were not merged
1029 // into a single one is that such a method would require several "if
1030 // allocation is not humongous do this, otherwise do that"
1031 // conditional paths which would obscure its flow. In fact, an early
1032 // version of this code did use a unified method which was harder to
1033 // follow and, as a result, it had subtle bugs that were hard to
1034 // track down. So keeping these two methods separate allows each to
1035 // be more readable. It will be good to keep these two in sync as
1036 // much as possible.
1037
1038 assert_heap_not_locked_and_not_at_safepoint();
1039 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1040 "should only be called for humongous allocations");
1041
1042 // Humongous objects can exhaust the heap quickly, so we should check if we
1043 // need to start a marking cycle at each humongous object allocation. We do
1044 // the check before we do the actual allocation. The reason for doing it
1045 // before the allocation is that we avoid having to keep track of the newly
1046 // allocated memory while we do a GC.
1047 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1048 word_size)) {
1049 collect(GCCause::_g1_humongous_allocation);
1050 }
1051
1052 // We will loop until a) we manage to successfully perform the
1053 // allocation or b) we successfully schedule a collection which
1054 // fails to perform the allocation. b) is the only case when we'll
1055 // return NULL.
1056 HeapWord* result = NULL;
1057 for (int try_count = 1; /* we'll return */; try_count += 1) {
1058 bool should_try_gc;
1059 unsigned int gc_count_before;
1060
1061 {
1062 MutexLockerEx x(Heap_lock);
1063
1064 // Given that humongous objects are not allocated in young
1065 // regions, we'll first try to do the allocation without doing a
1066 // collection hoping that there's enough space in the heap.
1067 result = humongous_obj_allocate(word_size);
1068 if (result != NULL) {
1069 return result;
1070 }
1071
1072 if (GC_locker::is_active_and_needs_gc()) {
1073 should_try_gc = false;
1074 } else {
1075 // The GCLocker may not be active but the GCLocker initiated
1076 // GC may not yet have been performed (GCLocker::needs_gc()
1077 // returns true). In this case we do not try this GC and
1078 // wait until the GCLocker initiated GC is performed, and
1079 // then retry the allocation.
1080 if (GC_locker::needs_gc()) {
1081 should_try_gc = false;
1082 } else {
1083 // Read the GC count while still holding the Heap_lock.
1084 gc_count_before = total_collections();
1085 should_try_gc = true;
1086 }
1087 }
1088 }
1089
1090 if (should_try_gc) {
1091 // If we failed to allocate the humongous object, we should try to
1092 // do a collection pause (if we're allowed) in case it reclaims
1093 // enough space for the allocation to succeed after the pause.
1094
1095 bool succeeded;
1096 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1097 if (result != NULL) {
1098 assert(succeeded, "only way to get back a non-NULL result");
1099 return result;
1100 }
1101
1102 if (succeeded) {
1103 // If we get here we successfully scheduled a collection which
1104 // failed to allocate. No point in trying to allocate
1105 // further. We'll just return NULL.
1106 MutexLockerEx x(Heap_lock);
1107 *gc_count_before_ret = total_collections();
1108 return NULL;
1109 }
1110 } else {
1111 // The GCLocker is either active or the GCLocker initiated
1112 // GC has not yet been performed. Stall until it is and
1113 // then retry the allocation.
1114 GC_locker::stall_until_clear();
1115 }
1116
1117 // We can reach here if we were unsuccessful in scheduling a
1118 // collection (because another thread beat us to it) or if we were
1119 // stalled due to the GC locker. In either can we should retry the
1120 // allocation attempt in case another thread successfully
1121 // performed a collection and reclaimed enough space. Give a
1122 // warning if we seem to be looping forever.
1123
1124 if ((QueuedAllocationWarningCount > 0) &&
1125 (try_count % QueuedAllocationWarningCount == 0)) {
1126 warning("G1CollectedHeap::attempt_allocation_humongous() "
1127 "retries %d times", try_count);
1128 }
1129 }
1130
1131 ShouldNotReachHere();
1132 return NULL;
1133 }
1134
1135 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1136 bool expect_null_mutator_alloc_region) {
1137 assert_at_safepoint(true /* should_be_vm_thread */);
1138 assert(_mutator_alloc_region.get() == NULL ||
1139 !expect_null_mutator_alloc_region,
1140 "the current alloc region was unexpectedly found to be non-NULL");
1141
1142 if (!isHumongous(word_size)) {
1143 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1144 false /* bot_updates */);
1145 } else {
1146 HeapWord* result = humongous_obj_allocate(word_size);
1147 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1148 g1_policy()->set_initiate_conc_mark_if_possible();
1149 }
1150 return result;
1151 }
1152
1153 ShouldNotReachHere();
1154 }
1155
1156 class PostMCRemSetClearClosure: public HeapRegionClosure {
1157 G1CollectedHeap* _g1h;
1158 ModRefBarrierSet* _mr_bs;
1159 public:
1160 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1161 _g1h(g1h), _mr_bs(mr_bs) { }
1162 bool doHeapRegion(HeapRegion* r) {
1163 if (r->continuesHumongous()) {
1164 return false;
1165 }
1166 _g1h->reset_gc_time_stamps(r);
1167 HeapRegionRemSet* hrrs = r->rem_set();
1168 if (hrrs != NULL) hrrs->clear();
1169 // You might think here that we could clear just the cards
1170 // corresponding to the used region. But no: if we leave a dirty card
1171 // in a region we might allocate into, then it would prevent that card
1172 // from being enqueued, and cause it to be missed.
1173 // Re: the performance cost: we shouldn't be doing full GC anyway!
1174 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1175 return false;
1176 }
1177 };
1178
1179 void G1CollectedHeap::clear_rsets_post_compaction() {
1180 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1181 heap_region_iterate(&rs_clear);
1182 }
1183
1184 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1185 G1CollectedHeap* _g1h;
1186 UpdateRSOopClosure _cl;
1187 int _worker_i;
1188 public:
1189 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1190 _cl(g1->g1_rem_set(), worker_i),
1191 _worker_i(worker_i),
1192 _g1h(g1)
1193 { }
1194
1195 bool doHeapRegion(HeapRegion* r) {
1196 if (!r->continuesHumongous()) {
1197 _cl.set_from(r);
1198 r->oop_iterate(&_cl);
1199 }
1200 return false;
1201 }
1202 };
1203
1204 class ParRebuildRSTask: public AbstractGangTask {
1205 G1CollectedHeap* _g1;
1206 public:
1207 ParRebuildRSTask(G1CollectedHeap* g1)
1208 : AbstractGangTask("ParRebuildRSTask"),
1209 _g1(g1)
1210 { }
1211
1212 void work(uint worker_id) {
1213 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1214 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1215 _g1->workers()->active_workers(),
1216 HeapRegion::RebuildRSClaimValue);
1217 }
1218 };
1219
1220 class PostCompactionPrinterClosure: public HeapRegionClosure {
1221 private:
1222 G1HRPrinter* _hr_printer;
1223 public:
1224 bool doHeapRegion(HeapRegion* hr) {
1225 assert(!hr->is_young(), "not expecting to find young regions");
1226 // We only generate output for non-empty regions.
1227 if (!hr->is_empty()) {
1228 if (!hr->isHumongous()) {
1229 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1230 } else if (hr->startsHumongous()) {
1231 if (hr->region_num() == 1) {
1232 // single humongous region
1233 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1234 } else {
1235 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1236 }
1237 } else {
1238 assert(hr->continuesHumongous(), "only way to get here");
1239 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1240 }
1241 }
1242 return false;
1243 }
1244
1245 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1246 : _hr_printer(hr_printer) { }
1247 };
1248
1249 void G1CollectedHeap::print_hrs_post_compaction() {
1250 PostCompactionPrinterClosure cl(hr_printer());
1251 heap_region_iterate(&cl);
1252 }
1253
1254 double G1CollectedHeap::verify(bool guard, const char* msg) {
1255 double verify_time_ms = 0.0;
1256
1257 if (guard && total_collections() >= VerifyGCStartAt) {
1258 double verify_start = os::elapsedTime();
1259 HandleMark hm; // Discard invalid handles created during verification
1260 gclog_or_tty->print(msg);
1261 prepare_for_verify();
1262 Universe::verify(false /* silent */, VerifyOption_G1UsePrevMarking);
1263 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
1264 }
1265
1266 return verify_time_ms;
1267 }
1268
1269 void G1CollectedHeap::verify_before_gc() {
1270 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
1271 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
1272 }
1273
1274 void G1CollectedHeap::verify_after_gc() {
1275 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
1276 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
1277 }
1278
1279 bool G1CollectedHeap::do_collection(bool explicit_gc,
1280 bool clear_all_soft_refs,
1281 size_t word_size) {
1282 assert_at_safepoint(true /* should_be_vm_thread */);
1283
1284 if (GC_locker::check_active_before_gc()) {
1285 return false;
1286 }
1287
1288 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1289 gc_timer->register_gc_start(os::elapsed_counter());
1290
1291 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1292 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1293
1294 SvcGCMarker sgcm(SvcGCMarker::FULL);
1295 ResourceMark rm;
1296
1297 print_heap_before_gc();
1298 trace_heap_before_gc(gc_tracer);
1299
1300 HRSPhaseSetter x(HRSPhaseFullGC);
1301 verify_region_sets_optional();
1302
1303 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1304 collector_policy()->should_clear_all_soft_refs();
1305
1306 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1307
1308 {
1309 IsGCActiveMark x;
1310
1311 // Timing
1312 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1313 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1314 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1315
1316 {
1317 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1318 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1319 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1320
1321 double start = os::elapsedTime();
1322 g1_policy()->record_full_collection_start();
1323
1324 // Note: When we have a more flexible GC logging framework that
1325 // allows us to add optional attributes to a GC log record we
1326 // could consider timing and reporting how long we wait in the
1327 // following two methods.
1328 wait_while_free_regions_coming();
1329 // If we start the compaction before the CM threads finish
1330 // scanning the root regions we might trip them over as we'll
1331 // be moving objects / updating references. So let's wait until
1332 // they are done. By telling them to abort, they should complete
1333 // early.
1334 _cm->root_regions()->abort();
1335 _cm->root_regions()->wait_until_scan_finished();
1336 append_secondary_free_list_if_not_empty_with_lock();
1337
1338 gc_prologue(true);
1339 increment_total_collections(true /* full gc */);
1340 increment_old_marking_cycles_started();
1341
1342 assert(used() == recalculate_used(), "Should be equal");
1343
1344 verify_before_gc();
1345
1346 pre_full_gc_dump(gc_timer);
1347
1348 COMPILER2_PRESENT(DerivedPointerTable::clear());
1349
1350 // Disable discovery and empty the discovered lists
1351 // for the CM ref processor.
1352 ref_processor_cm()->disable_discovery();
1353 ref_processor_cm()->abandon_partial_discovery();
1354 ref_processor_cm()->verify_no_references_recorded();
1355
1356 // Abandon current iterations of concurrent marking and concurrent
1357 // refinement, if any are in progress. We have to do this before
1358 // wait_until_scan_finished() below.
1359 concurrent_mark()->abort();
1360
1361 // Make sure we'll choose a new allocation region afterwards.
1362 release_mutator_alloc_region();
1363 abandon_gc_alloc_regions();
1364 g1_rem_set()->cleanupHRRS();
1365
1366 // We should call this after we retire any currently active alloc
1367 // regions so that all the ALLOC / RETIRE events are generated
1368 // before the start GC event.
1369 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1370
1371 // We may have added regions to the current incremental collection
1372 // set between the last GC or pause and now. We need to clear the
1373 // incremental collection set and then start rebuilding it afresh
1374 // after this full GC.
1375 abandon_collection_set(g1_policy()->inc_cset_head());
1376 g1_policy()->clear_incremental_cset();
1377 g1_policy()->stop_incremental_cset_building();
1378
1379 tear_down_region_sets(false /* free_list_only */);
1380 g1_policy()->set_gcs_are_young(true);
1381
1382 // See the comments in g1CollectedHeap.hpp and
1383 // G1CollectedHeap::ref_processing_init() about
1384 // how reference processing currently works in G1.
1385
1386 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1387 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1388
1389 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1390 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1391
1392 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1393 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1394
1395 // Do collection work
1396 {
1397 HandleMark hm; // Discard invalid handles created during gc
1398 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1399 }
1400
1401 assert(free_regions() == 0, "we should not have added any free regions");
1402 rebuild_region_sets(false /* free_list_only */);
1403
1404 // Enqueue any discovered reference objects that have
1405 // not been removed from the discovered lists.
1406 ref_processor_stw()->enqueue_discovered_references();
1407
1408 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1409
1410 MemoryService::track_memory_usage();
1411
1412 verify_after_gc();
1413
1414 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1415 ref_processor_stw()->verify_no_references_recorded();
1416
1417 // Note: since we've just done a full GC, concurrent
1418 // marking is no longer active. Therefore we need not
1419 // re-enable reference discovery for the CM ref processor.
1420 // That will be done at the start of the next marking cycle.
1421 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1422 ref_processor_cm()->verify_no_references_recorded();
1423
1424 reset_gc_time_stamp();
1425 // Since everything potentially moved, we will clear all remembered
1426 // sets, and clear all cards. Later we will rebuild remembered
1427 // sets. We will also reset the GC time stamps of the regions.
1428 clear_rsets_post_compaction();
1429 check_gc_time_stamps();
1430
1431 // Resize the heap if necessary.
1432 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1433
1434 if (_hr_printer.is_active()) {
1435 // We should do this after we potentially resize the heap so
1436 // that all the COMMIT / UNCOMMIT events are generated before
1437 // the end GC event.
1438
1439 print_hrs_post_compaction();
1440 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1441 }
1442
1443 if (_cg1r->use_cache()) {
1444 _cg1r->clear_and_record_card_counts();
1445 _cg1r->clear_hot_cache();
1446 }
1447
1448 // Rebuild remembered sets of all regions.
1449 if (G1CollectedHeap::use_parallel_gc_threads()) {
1450 uint n_workers =
1451 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1452 workers()->active_workers(),
1453 Threads::number_of_non_daemon_threads());
1454 assert(UseDynamicNumberOfGCThreads ||
1455 n_workers == workers()->total_workers(),
1456 "If not dynamic should be using all the workers");
1457 workers()->set_active_workers(n_workers);
1458 // Set parallel threads in the heap (_n_par_threads) only
1459 // before a parallel phase and always reset it to 0 after
1460 // the phase so that the number of parallel threads does
1461 // no get carried forward to a serial phase where there
1462 // may be code that is "possibly_parallel".
1463 set_par_threads(n_workers);
1464
1465 ParRebuildRSTask rebuild_rs_task(this);
1466 assert(check_heap_region_claim_values(
1467 HeapRegion::InitialClaimValue), "sanity check");
1468 assert(UseDynamicNumberOfGCThreads ||
1469 workers()->active_workers() == workers()->total_workers(),
1470 "Unless dynamic should use total workers");
1471 // Use the most recent number of active workers
1472 assert(workers()->active_workers() > 0,
1473 "Active workers not properly set");
1474 set_par_threads(workers()->active_workers());
1475 workers()->run_task(&rebuild_rs_task);
1476 set_par_threads(0);
1477 assert(check_heap_region_claim_values(
1478 HeapRegion::RebuildRSClaimValue), "sanity check");
1479 reset_heap_region_claim_values();
1480 } else {
1481 RebuildRSOutOfRegionClosure rebuild_rs(this);
1482 heap_region_iterate(&rebuild_rs);
1483 }
1484
1485 if (true) { // FIXME
1486 // Ask the permanent generation to adjust size for full collections
1487 perm()->compute_new_size();
1488 }
1489
1490 #ifdef TRACESPINNING
1491 ParallelTaskTerminator::print_termination_counts();
1492 #endif
1493
1494 // Discard all rset updates
1495 JavaThread::dirty_card_queue_set().abandon_logs();
1496 assert(!G1DeferredRSUpdate
1497 || (G1DeferredRSUpdate &&
1498 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1499
1500 _young_list->reset_sampled_info();
1501 // At this point there should be no regions in the
1502 // entire heap tagged as young.
1503 assert(check_young_list_empty(true /* check_heap */),
1504 "young list should be empty at this point");
1505
1506 // Update the number of full collections that have been completed.
1507 increment_old_marking_cycles_completed(false /* concurrent */);
1508
1509 _hrs.verify_optional();
1510 verify_region_sets_optional();
1511
1512 // Start a new incremental collection set for the next pause
1513 assert(g1_policy()->collection_set() == NULL, "must be");
1514 g1_policy()->start_incremental_cset_building();
1515
1516 // Clear the _cset_fast_test bitmap in anticipation of adding
1517 // regions to the incremental collection set for the next
1518 // evacuation pause.
1519 clear_cset_fast_test();
1520
1521 init_mutator_alloc_region();
1522
1523 double end = os::elapsedTime();
1524 g1_policy()->record_full_collection_end();
1525
1526 if (G1Log::fine()) {
1527 g1_policy()->print_heap_transition();
1528 }
1529
1530 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1531 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1532 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1533 // before any GC notifications are raised.
1534 g1mm()->update_sizes();
1535
1536 gc_epilogue(true);
1537 }
1538
1539 if (G1Log::finer()) {
1540 g1_policy()->print_detailed_heap_transition();
1541 }
1542
1543 print_heap_after_gc();
1544 trace_heap_after_gc(gc_tracer);
1545
1546 post_full_gc_dump(gc_timer);
1547 }
1548
1549 gc_timer->register_gc_end(os::elapsed_counter());
1550
1551 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1552
1553 return true;
1554 }
1555
1556 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1557 // do_collection() will return whether it succeeded in performing
1558 // the GC. Currently, there is no facility on the
1559 // do_full_collection() API to notify the caller than the collection
1560 // did not succeed (e.g., because it was locked out by the GC
1561 // locker). So, right now, we'll ignore the return value.
1562 bool dummy = do_collection(true, /* explicit_gc */
1563 clear_all_soft_refs,
1564 0 /* word_size */);
1565 }
1566
1567 // This code is mostly copied from TenuredGeneration.
1568 void
1569 G1CollectedHeap::
1570 resize_if_necessary_after_full_collection(size_t word_size) {
1571 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1572
1573 // Include the current allocation, if any, and bytes that will be
1574 // pre-allocated to support collections, as "used".
1575 const size_t used_after_gc = used();
1576 const size_t capacity_after_gc = capacity();
1577 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1578
1579 // This is enforced in arguments.cpp.
1580 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1581 "otherwise the code below doesn't make sense");
1582
1583 // We don't have floating point command-line arguments
1584 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1585 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1586 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1587 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1588
1589 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1590 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1591
1592 // We have to be careful here as these two calculations can overflow
1593 // 32-bit size_t's.
1594 double used_after_gc_d = (double) used_after_gc;
1595 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1596 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1597
1598 // Let's make sure that they are both under the max heap size, which
1599 // by default will make them fit into a size_t.
1600 double desired_capacity_upper_bound = (double) max_heap_size;
1601 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1602 desired_capacity_upper_bound);
1603 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1604 desired_capacity_upper_bound);
1605
1606 // We can now safely turn them into size_t's.
1607 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1608 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1609
1610 // This assert only makes sense here, before we adjust them
1611 // with respect to the min and max heap size.
1612 assert(minimum_desired_capacity <= maximum_desired_capacity,
1613 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1614 "maximum_desired_capacity = "SIZE_FORMAT,
1615 minimum_desired_capacity, maximum_desired_capacity));
1616
1617 // Should not be greater than the heap max size. No need to adjust
1618 // it with respect to the heap min size as it's a lower bound (i.e.,
1619 // we'll try to make the capacity larger than it, not smaller).
1620 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1621 // Should not be less than the heap min size. No need to adjust it
1622 // with respect to the heap max size as it's an upper bound (i.e.,
1623 // we'll try to make the capacity smaller than it, not greater).
1624 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1625
1626 if (capacity_after_gc < minimum_desired_capacity) {
1627 // Don't expand unless it's significant
1628 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1629 ergo_verbose4(ErgoHeapSizing,
1630 "attempt heap expansion",
1631 ergo_format_reason("capacity lower than "
1632 "min desired capacity after Full GC")
1633 ergo_format_byte("capacity")
1634 ergo_format_byte("occupancy")
1635 ergo_format_byte_perc("min desired capacity"),
1636 capacity_after_gc, used_after_gc,
1637 minimum_desired_capacity, (double) MinHeapFreeRatio);
1638 expand(expand_bytes);
1639
1640 // No expansion, now see if we want to shrink
1641 } else if (capacity_after_gc > maximum_desired_capacity) {
1642 // Capacity too large, compute shrinking size
1643 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1644 ergo_verbose4(ErgoHeapSizing,
1645 "attempt heap shrinking",
1646 ergo_format_reason("capacity higher than "
1647 "max desired capacity after Full GC")
1648 ergo_format_byte("capacity")
1649 ergo_format_byte("occupancy")
1650 ergo_format_byte_perc("max desired capacity"),
1651 capacity_after_gc, used_after_gc,
1652 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1653 shrink(shrink_bytes);
1654 }
1655 }
1656
1657
1658 HeapWord*
1659 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1660 bool* succeeded) {
1661 assert_at_safepoint(true /* should_be_vm_thread */);
1662
1663 *succeeded = true;
1664 // Let's attempt the allocation first.
1665 HeapWord* result =
1666 attempt_allocation_at_safepoint(word_size,
1667 false /* expect_null_mutator_alloc_region */);
1668 if (result != NULL) {
1669 assert(*succeeded, "sanity");
1670 return result;
1671 }
1672
1673 // In a G1 heap, we're supposed to keep allocation from failing by
1674 // incremental pauses. Therefore, at least for now, we'll favor
1675 // expansion over collection. (This might change in the future if we can
1676 // do something smarter than full collection to satisfy a failed alloc.)
1677 result = expand_and_allocate(word_size);
1678 if (result != NULL) {
1679 assert(*succeeded, "sanity");
1680 return result;
1681 }
1682
1683 // Expansion didn't work, we'll try to do a Full GC.
1684 bool gc_succeeded = do_collection(false, /* explicit_gc */
1685 false, /* clear_all_soft_refs */
1686 word_size);
1687 if (!gc_succeeded) {
1688 *succeeded = false;
1689 return NULL;
1690 }
1691
1692 // Retry the allocation
1693 result = attempt_allocation_at_safepoint(word_size,
1694 true /* expect_null_mutator_alloc_region */);
1695 if (result != NULL) {
1696 assert(*succeeded, "sanity");
1697 return result;
1698 }
1699
1700 // Then, try a Full GC that will collect all soft references.
1701 gc_succeeded = do_collection(false, /* explicit_gc */
1702 true, /* clear_all_soft_refs */
1703 word_size);
1704 if (!gc_succeeded) {
1705 *succeeded = false;
1706 return NULL;
1707 }
1708
1709 // Retry the allocation once more
1710 result = attempt_allocation_at_safepoint(word_size,
1711 true /* expect_null_mutator_alloc_region */);
1712 if (result != NULL) {
1713 assert(*succeeded, "sanity");
1714 return result;
1715 }
1716
1717 assert(!collector_policy()->should_clear_all_soft_refs(),
1718 "Flag should have been handled and cleared prior to this point");
1719
1720 // What else? We might try synchronous finalization later. If the total
1721 // space available is large enough for the allocation, then a more
1722 // complete compaction phase than we've tried so far might be
1723 // appropriate.
1724 assert(*succeeded, "sanity");
1725 return NULL;
1726 }
1727
1728 // Attempting to expand the heap sufficiently
1729 // to support an allocation of the given "word_size". If
1730 // successful, perform the allocation and return the address of the
1731 // allocated block, or else "NULL".
1732
1733 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1734 assert_at_safepoint(true /* should_be_vm_thread */);
1735
1736 verify_region_sets_optional();
1737
1738 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1739 ergo_verbose1(ErgoHeapSizing,
1740 "attempt heap expansion",
1741 ergo_format_reason("allocation request failed")
1742 ergo_format_byte("allocation request"),
1743 word_size * HeapWordSize);
1744 if (expand(expand_bytes)) {
1745 _hrs.verify_optional();
1746 verify_region_sets_optional();
1747 return attempt_allocation_at_safepoint(word_size,
1748 false /* expect_null_mutator_alloc_region */);
1749 }
1750 return NULL;
1751 }
1752
1753 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1754 HeapWord* new_end) {
1755 assert(old_end != new_end, "don't call this otherwise");
1756 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1757
1758 // Update the committed mem region.
1759 _g1_committed.set_end(new_end);
1760 // Tell the card table about the update.
1761 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1762 // Tell the BOT about the update.
1763 _bot_shared->resize(_g1_committed.word_size());
1764 }
1765
1766 bool G1CollectedHeap::expand(size_t expand_bytes) {
1767 size_t old_mem_size = _g1_storage.committed_size();
1768 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1769 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1770 HeapRegion::GrainBytes);
1771 ergo_verbose2(ErgoHeapSizing,
1772 "expand the heap",
1773 ergo_format_byte("requested expansion amount")
1774 ergo_format_byte("attempted expansion amount"),
1775 expand_bytes, aligned_expand_bytes);
1776
1777 // First commit the memory.
1778 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1779 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1780 if (successful) {
1781 // Then propagate this update to the necessary data structures.
1782 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1783 update_committed_space(old_end, new_end);
1784
1785 FreeRegionList expansion_list("Local Expansion List");
1786 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1787 assert(mr.start() == old_end, "post-condition");
1788 // mr might be a smaller region than what was requested if
1789 // expand_by() was unable to allocate the HeapRegion instances
1790 assert(mr.end() <= new_end, "post-condition");
1791
1792 size_t actual_expand_bytes = mr.byte_size();
1793 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1794 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1795 "post-condition");
1796 if (actual_expand_bytes < aligned_expand_bytes) {
1797 // We could not expand _hrs to the desired size. In this case we
1798 // need to shrink the committed space accordingly.
1799 assert(mr.end() < new_end, "invariant");
1800
1801 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1802 // First uncommit the memory.
1803 _g1_storage.shrink_by(diff_bytes);
1804 // Then propagate this update to the necessary data structures.
1805 update_committed_space(new_end, mr.end());
1806 }
1807 _free_list.add_as_tail(&expansion_list);
1808
1809 if (_hr_printer.is_active()) {
1810 HeapWord* curr = mr.start();
1811 while (curr < mr.end()) {
1812 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1813 _hr_printer.commit(curr, curr_end);
1814 curr = curr_end;
1815 }
1816 assert(curr == mr.end(), "post-condition");
1817 }
1818 g1_policy()->record_new_heap_size(n_regions());
1819 } else {
1820 ergo_verbose0(ErgoHeapSizing,
1821 "did not expand the heap",
1822 ergo_format_reason("heap expansion operation failed"));
1823 // The expansion of the virtual storage space was unsuccessful.
1824 // Let's see if it was because we ran out of swap.
1825 if (G1ExitOnExpansionFailure &&
1826 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1827 // We had head room...
1828 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1829 }
1830 }
1831 return successful;
1832 }
1833
1834 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1835 size_t old_mem_size = _g1_storage.committed_size();
1836 size_t aligned_shrink_bytes =
1837 ReservedSpace::page_align_size_down(shrink_bytes);
1838 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1839 HeapRegion::GrainBytes);
1840 uint num_regions_deleted = 0;
1841 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1842 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1843 assert(mr.end() == old_end, "post-condition");
1844
1845 ergo_verbose3(ErgoHeapSizing,
1846 "shrink the heap",
1847 ergo_format_byte("requested shrinking amount")
1848 ergo_format_byte("aligned shrinking amount")
1849 ergo_format_byte("attempted shrinking amount"),
1850 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1851 if (mr.byte_size() > 0) {
1852 if (_hr_printer.is_active()) {
1853 HeapWord* curr = mr.end();
1854 while (curr > mr.start()) {
1855 HeapWord* curr_end = curr;
1856 curr -= HeapRegion::GrainWords;
1857 _hr_printer.uncommit(curr, curr_end);
1858 }
1859 assert(curr == mr.start(), "post-condition");
1860 }
1861
1862 _g1_storage.shrink_by(mr.byte_size());
1863 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1864 assert(mr.start() == new_end, "post-condition");
1865
1866 _expansion_regions += num_regions_deleted;
1867 update_committed_space(old_end, new_end);
1868 HeapRegionRemSet::shrink_heap(n_regions());
1869 g1_policy()->record_new_heap_size(n_regions());
1870 } else {
1871 ergo_verbose0(ErgoHeapSizing,
1872 "did not shrink the heap",
1873 ergo_format_reason("heap shrinking operation failed"));
1874 }
1875 }
1876
1877 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1878 verify_region_sets_optional();
1879
1880 // We should only reach here at the end of a Full GC which means we
1881 // should not not be holding to any GC alloc regions. The method
1882 // below will make sure of that and do any remaining clean up.
1883 abandon_gc_alloc_regions();
1884
1885 // Instead of tearing down / rebuilding the free lists here, we
1886 // could instead use the remove_all_pending() method on free_list to
1887 // remove only the ones that we need to remove.
1888 tear_down_region_sets(true /* free_list_only */);
1889 shrink_helper(shrink_bytes);
1890 rebuild_region_sets(true /* free_list_only */);
1891
1892 _hrs.verify_optional();
1893 verify_region_sets_optional();
1894 }
1895
1896 // Public methods.
1897
1898 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1899 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1900 #endif // _MSC_VER
1901
1902
1903 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1904 SharedHeap(policy_),
1905 _g1_policy(policy_),
1906 _dirty_card_queue_set(false),
1907 _into_cset_dirty_card_queue_set(false),
1908 _is_alive_closure_cm(this),
1909 _is_alive_closure_stw(this),
1910 _ref_processor_cm(NULL),
1911 _ref_processor_stw(NULL),
1912 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1913 _bot_shared(NULL),
1914 _evac_failure_scan_stack(NULL),
1915 _mark_in_progress(false),
1916 _cg1r(NULL), _summary_bytes_used(0),
1917 _g1mm(NULL),
1918 _refine_cte_cl(NULL),
1919 _full_collection(false),
1920 _free_list("Master Free List"),
1921 _secondary_free_list("Secondary Free List"),
1922 _old_set("Old Set"),
1923 _humongous_set("Master Humongous Set"),
1924 _free_regions_coming(false),
1925 _young_list(new YoungList(this)),
1926 _gc_time_stamp(0),
1927 _retained_old_gc_alloc_region(NULL),
1928 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1929 _old_plab_stats(OldPLABSize, PLABWeight),
1930 _expand_heap_after_alloc_failure(true),
1931 _surviving_young_words(NULL),
1932 _old_marking_cycles_started(0),
1933 _old_marking_cycles_completed(0),
1934 _concurrent_cycle_started(false),
1935 _in_cset_fast_test(NULL),
1936 _in_cset_fast_test_base(NULL),
1937 _dirty_cards_region_list(NULL),
1938 _worker_cset_start_region(NULL),
1939 _worker_cset_start_region_time_stamp(NULL),
1940 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1941 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1942 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1943 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1944
1945 _g1h = this;
1946 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1947 vm_exit_during_initialization("Failed necessary allocation.");
1948 }
1949
1950 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1951
1952 int n_queues = MAX2((int)ParallelGCThreads, 1);
1953 _task_queues = new RefToScanQueueSet(n_queues);
1954
1955 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1956 assert(n_rem_sets > 0, "Invariant.");
1957
1958 HeapRegionRemSetIterator** iter_arr = NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues, mtGC);
1959 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1960 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1961 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1962
1963 for (int i = 0; i < n_queues; i++) {
1964 RefToScanQueue* q = new RefToScanQueue();
1965 q->initialize();
1966 _task_queues->register_queue(i, q);
1967 iter_arr[i] = new HeapRegionRemSetIterator();
1968 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1969 }
1970 _rem_set_iterator = iter_arr;
1971
1972 clear_cset_start_regions();
1973
1974 // Initialize the G1EvacuationFailureALot counters and flags.
1975 NOT_PRODUCT(reset_evacuation_should_fail();)
1976
1977 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1978 }
1979
1980 jint G1CollectedHeap::initialize() {
1981 CollectedHeap::pre_initialize();
1982 os::enable_vtime();
1983
1984 G1Log::init();
1985
1986 // Necessary to satisfy locking discipline assertions.
1987
1988 MutexLocker x(Heap_lock);
1989
1990 // We have to initialize the printer before committing the heap, as
1991 // it will be used then.
1992 _hr_printer.set_active(G1PrintHeapRegions);
1993
1994 // While there are no constraints in the GC code that HeapWordSize
1995 // be any particular value, there are multiple other areas in the
1996 // system which believe this to be true (e.g. oop->object_size in some
1997 // cases incorrectly returns the size in wordSize units rather than
1998 // HeapWordSize).
1999 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2000
2001 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2002 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2003
2004 // Ensure that the sizes are properly aligned.
2005 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2006 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2007
2008 _cg1r = new ConcurrentG1Refine();
2009
2010 // Reserve the maximum.
2011 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
2012 // Includes the perm-gen.
2013
2014 // When compressed oops are enabled, the preferred heap base
2015 // is calculated by subtracting the requested size from the
2016 // 32Gb boundary and using the result as the base address for
2017 // heap reservation. If the requested size is not aligned to
2018 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2019 // into the ReservedHeapSpace constructor) then the actual
2020 // base of the reserved heap may end up differing from the
2021 // address that was requested (i.e. the preferred heap base).
2022 // If this happens then we could end up using a non-optimal
2023 // compressed oops mode.
2024
2025 // Since max_byte_size is aligned to the size of a heap region (checked
2026 // above), we also need to align the perm gen size as it might not be.
2027 size_t total_reserved = 0;
2028
2029 total_reserved = add_and_check_overflow(total_reserved, max_byte_size);
2030 size_t pg_max_size = (size_t) align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
2031 total_reserved = add_and_check_overflow(total_reserved, pg_max_size);
2032
2033 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
2034
2035 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
2036
2037 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
2038 UseLargePages, addr);
2039
2040 if (UseCompressedOops) {
2041 if (addr != NULL && !heap_rs.is_reserved()) {
2042 // Failed to reserve at specified address - the requested memory
2043 // region is taken already, for example, by 'java' launcher.
2044 // Try again to reserver heap higher.
2045 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
2046
2047 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
2048 UseLargePages, addr);
2049
2050 if (addr != NULL && !heap_rs0.is_reserved()) {
2051 // Failed to reserve at specified address again - give up.
2052 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
2053 assert(addr == NULL, "");
2054
2055 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
2056 UseLargePages, addr);
2057 heap_rs = heap_rs1;
2058 } else {
2059 heap_rs = heap_rs0;
2060 }
2061 }
2062 }
2063
2064 if (!heap_rs.is_reserved()) {
2065 vm_exit_during_initialization("Could not reserve enough space for object heap");
2066 return JNI_ENOMEM;
2067 }
2068
2069 // It is important to do this in a way such that concurrent readers can't
2070 // temporarily think something is in the heap. (I've actually seen this
2071 // happen in asserts: DLD.)
2072 _reserved.set_word_size(0);
2073 _reserved.set_start((HeapWord*)heap_rs.base());
2074 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2075
2076 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2077
2078 // Create the gen rem set (and barrier set) for the entire reserved region.
2079 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2080 set_barrier_set(rem_set()->bs());
2081 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2082 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2083 } else {
2084 vm_exit_during_initialization("G1 requires a mod ref bs.");
2085 return JNI_ENOMEM;
2086 }
2087
2088 // Also create a G1 rem set.
2089 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2090 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2091 } else {
2092 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2093 return JNI_ENOMEM;
2094 }
2095
2096 // Carve out the G1 part of the heap.
2097
2098 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2099 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2100 g1_rs.size()/HeapWordSize);
2101 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
2102
2103 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2104
2105 _g1_storage.initialize(g1_rs, 0);
2106 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2107 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2108 (HeapWord*) _g1_reserved.end(),
2109 _expansion_regions);
2110
2111 // 6843694 - ensure that the maximum region index can fit
2112 // in the remembered set structures.
2113 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2114 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2115
2116 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2117 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2118 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2119 "too many cards per region");
2120
2121 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2122
2123 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2124 heap_word_size(init_byte_size));
2125
2126 _g1h = this;
2127
2128 _in_cset_fast_test_length = max_regions();
2129 _in_cset_fast_test_base =
2130 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2131
2132 // We're biasing _in_cset_fast_test to avoid subtracting the
2133 // beginning of the heap every time we want to index; basically
2134 // it's the same with what we do with the card table.
2135 _in_cset_fast_test = _in_cset_fast_test_base -
2136 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2137
2138 // Clear the _cset_fast_test bitmap in anticipation of adding
2139 // regions to the incremental collection set for the first
2140 // evacuation pause.
2141 clear_cset_fast_test();
2142
2143 // Create the ConcurrentMark data structure and thread.
2144 // (Must do this late, so that "max_regions" is defined.)
2145 _cm = new ConcurrentMark(heap_rs, max_regions());
2146 _cmThread = _cm->cmThread();
2147
2148 // Initialize the from_card cache structure of HeapRegionRemSet.
2149 HeapRegionRemSet::init_heap(max_regions());
2150
2151 // Now expand into the initial heap size.
2152 if (!expand(init_byte_size)) {
2153 vm_exit_during_initialization("Failed to allocate initial heap.");
2154 return JNI_ENOMEM;
2155 }
2156
2157 // Perform any initialization actions delegated to the policy.
2158 g1_policy()->init();
2159
2160 _refine_cte_cl =
2161 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2162 g1_rem_set(),
2163 concurrent_g1_refine());
2164 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2165
2166 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2167 SATB_Q_FL_lock,
2168 G1SATBProcessCompletedThreshold,
2169 Shared_SATB_Q_lock);
2170
2171 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2172 DirtyCardQ_FL_lock,
2173 concurrent_g1_refine()->yellow_zone(),
2174 concurrent_g1_refine()->red_zone(),
2175 Shared_DirtyCardQ_lock);
2176
2177 if (G1DeferredRSUpdate) {
2178 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2179 DirtyCardQ_FL_lock,
2180 -1, // never trigger processing
2181 -1, // no limit on length
2182 Shared_DirtyCardQ_lock,
2183 &JavaThread::dirty_card_queue_set());
2184 }
2185
2186 // Initialize the card queue set used to hold cards containing
2187 // references into the collection set.
2188 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2189 DirtyCardQ_FL_lock,
2190 -1, // never trigger processing
2191 -1, // no limit on length
2192 Shared_DirtyCardQ_lock,
2193 &JavaThread::dirty_card_queue_set());
2194
2195 // In case we're keeping closure specialization stats, initialize those
2196 // counts and that mechanism.
2197 SpecializationStats::clear();
2198
2199 // Do later initialization work for concurrent refinement.
2200 _cg1r->init();
2201
2202 // Here we allocate the dummy full region that is required by the
2203 // G1AllocRegion class. If we don't pass an address in the reserved
2204 // space here, lots of asserts fire.
2205
2206 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2207 _g1_reserved.start());
2208 // We'll re-use the same region whether the alloc region will
2209 // require BOT updates or not and, if it doesn't, then a non-young
2210 // region will complain that it cannot support allocations without
2211 // BOT updates. So we'll tag the dummy region as young to avoid that.
2212 dummy_region->set_young();
2213 // Make sure it's full.
2214 dummy_region->set_top(dummy_region->end());
2215 G1AllocRegion::setup(this, dummy_region);
2216
2217 init_mutator_alloc_region();
2218
2219 // Do create of the monitoring and management support so that
2220 // values in the heap have been properly initialized.
2221 _g1mm = new G1MonitoringSupport(this);
2222
2223 return JNI_OK;
2224 }
2225
2226 void G1CollectedHeap::ref_processing_init() {
2227 // Reference processing in G1 currently works as follows:
2228 //
2229 // * There are two reference processor instances. One is
2230 // used to record and process discovered references
2231 // during concurrent marking; the other is used to
2232 // record and process references during STW pauses
2233 // (both full and incremental).
2234 // * Both ref processors need to 'span' the entire heap as
2235 // the regions in the collection set may be dotted around.
2236 //
2237 // * For the concurrent marking ref processor:
2238 // * Reference discovery is enabled at initial marking.
2239 // * Reference discovery is disabled and the discovered
2240 // references processed etc during remarking.
2241 // * Reference discovery is MT (see below).
2242 // * Reference discovery requires a barrier (see below).
2243 // * Reference processing may or may not be MT
2244 // (depending on the value of ParallelRefProcEnabled
2245 // and ParallelGCThreads).
2246 // * A full GC disables reference discovery by the CM
2247 // ref processor and abandons any entries on it's
2248 // discovered lists.
2249 //
2250 // * For the STW processor:
2251 // * Non MT discovery is enabled at the start of a full GC.
2252 // * Processing and enqueueing during a full GC is non-MT.
2253 // * During a full GC, references are processed after marking.
2254 //
2255 // * Discovery (may or may not be MT) is enabled at the start
2256 // of an incremental evacuation pause.
2257 // * References are processed near the end of a STW evacuation pause.
2258 // * For both types of GC:
2259 // * Discovery is atomic - i.e. not concurrent.
2260 // * Reference discovery will not need a barrier.
2261
2262 SharedHeap::ref_processing_init();
2263 MemRegion mr = reserved_region();
2264
2265 // Concurrent Mark ref processor
2266 _ref_processor_cm =
2267 new ReferenceProcessor(mr, // span
2268 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2269 // mt processing
2270 (int) ParallelGCThreads,
2271 // degree of mt processing
2272 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2273 // mt discovery
2274 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2275 // degree of mt discovery
2276 false,
2277 // Reference discovery is not atomic
2278 &_is_alive_closure_cm,
2279 // is alive closure
2280 // (for efficiency/performance)
2281 true);
2282 // Setting next fields of discovered
2283 // lists requires a barrier.
2284
2285 // STW ref processor
2286 _ref_processor_stw =
2287 new ReferenceProcessor(mr, // span
2288 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2289 // mt processing
2290 MAX2((int)ParallelGCThreads, 1),
2291 // degree of mt processing
2292 (ParallelGCThreads > 1),
2293 // mt discovery
2294 MAX2((int)ParallelGCThreads, 1),
2295 // degree of mt discovery
2296 true,
2297 // Reference discovery is atomic
2298 &_is_alive_closure_stw,
2299 // is alive closure
2300 // (for efficiency/performance)
2301 false);
2302 // Setting next fields of discovered
2303 // lists requires a barrier.
2304 }
2305
2306 size_t G1CollectedHeap::capacity() const {
2307 return _g1_committed.byte_size();
2308 }
2309
2310 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2311 assert(!hr->continuesHumongous(), "pre-condition");
2312 hr->reset_gc_time_stamp();
2313 if (hr->startsHumongous()) {
2314 uint first_index = hr->hrs_index() + 1;
2315 uint last_index = hr->last_hc_index();
2316 for (uint i = first_index; i < last_index; i += 1) {
2317 HeapRegion* chr = region_at(i);
2318 assert(chr->continuesHumongous(), "sanity");
2319 chr->reset_gc_time_stamp();
2320 }
2321 }
2322 }
2323
2324 #ifndef PRODUCT
2325 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2326 private:
2327 unsigned _gc_time_stamp;
2328 bool _failures;
2329
2330 public:
2331 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2332 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2333
2334 virtual bool doHeapRegion(HeapRegion* hr) {
2335 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2336 if (_gc_time_stamp != region_gc_time_stamp) {
2337 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2338 "expected %d", HR_FORMAT_PARAMS(hr),
2339 region_gc_time_stamp, _gc_time_stamp);
2340 _failures = true;
2341 }
2342 return false;
2343 }
2344
2345 bool failures() { return _failures; }
2346 };
2347
2348 void G1CollectedHeap::check_gc_time_stamps() {
2349 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2350 heap_region_iterate(&cl);
2351 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2352 }
2353 #endif // PRODUCT
2354
2355 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2356 DirtyCardQueue* into_cset_dcq,
2357 bool concurrent,
2358 int worker_i) {
2359 // Clean cards in the hot card cache
2360 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2361
2362 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2363 int n_completed_buffers = 0;
2364 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2365 n_completed_buffers++;
2366 }
2367 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2368 dcqs.clear_n_completed_buffers();
2369 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2370 }
2371
2372
2373 // Computes the sum of the storage used by the various regions.
2374
2375 size_t G1CollectedHeap::used() const {
2376 assert(Heap_lock->owner() != NULL,
2377 "Should be owned on this thread's behalf.");
2378 size_t result = _summary_bytes_used;
2379 // Read only once in case it is set to NULL concurrently
2380 HeapRegion* hr = _mutator_alloc_region.get();
2381 if (hr != NULL)
2382 result += hr->used();
2383 return result;
2384 }
2385
2386 size_t G1CollectedHeap::used_unlocked() const {
2387 size_t result = _summary_bytes_used;
2388 return result;
2389 }
2390
2391 class SumUsedClosure: public HeapRegionClosure {
2392 size_t _used;
2393 public:
2394 SumUsedClosure() : _used(0) {}
2395 bool doHeapRegion(HeapRegion* r) {
2396 if (!r->continuesHumongous()) {
2397 _used += r->used();
2398 }
2399 return false;
2400 }
2401 size_t result() { return _used; }
2402 };
2403
2404 size_t G1CollectedHeap::recalculate_used() const {
2405 SumUsedClosure blk;
2406 heap_region_iterate(&blk);
2407 return blk.result();
2408 }
2409
2410 size_t G1CollectedHeap::unsafe_max_alloc() {
2411 if (free_regions() > 0) return HeapRegion::GrainBytes;
2412 // otherwise, is there space in the current allocation region?
2413
2414 // We need to store the current allocation region in a local variable
2415 // here. The problem is that this method doesn't take any locks and
2416 // there may be other threads which overwrite the current allocation
2417 // region field. attempt_allocation(), for example, sets it to NULL
2418 // and this can happen *after* the NULL check here but before the call
2419 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2420 // to be a problem in the optimized build, since the two loads of the
2421 // current allocation region field are optimized away.
2422 HeapRegion* hr = _mutator_alloc_region.get();
2423 if (hr == NULL) {
2424 return 0;
2425 }
2426 return hr->free();
2427 }
2428
2429 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2430 switch (cause) {
2431 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2432 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2433 case GCCause::_g1_humongous_allocation: return true;
2434 default: return false;
2435 }
2436 }
2437
2438 #ifndef PRODUCT
2439 void G1CollectedHeap::allocate_dummy_regions() {
2440 // Let's fill up most of the region
2441 size_t word_size = HeapRegion::GrainWords - 1024;
2442 // And as a result the region we'll allocate will be humongous.
2443 guarantee(isHumongous(word_size), "sanity");
2444
2445 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2446 // Let's use the existing mechanism for the allocation
2447 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2448 if (dummy_obj != NULL) {
2449 MemRegion mr(dummy_obj, word_size);
2450 CollectedHeap::fill_with_object(mr);
2451 } else {
2452 // If we can't allocate once, we probably cannot allocate
2453 // again. Let's get out of the loop.
2454 break;
2455 }
2456 }
2457 }
2458 #endif // !PRODUCT
2459
2460 void G1CollectedHeap::increment_old_marking_cycles_started() {
2461 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2462 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2463 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2464 _old_marking_cycles_started, _old_marking_cycles_completed));
2465
2466 _old_marking_cycles_started++;
2467 }
2468
2469 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2470 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2471
2472 // We assume that if concurrent == true, then the caller is a
2473 // concurrent thread that was joined the Suspendible Thread
2474 // Set. If there's ever a cheap way to check this, we should add an
2475 // assert here.
2476
2477 // Given that this method is called at the end of a Full GC or of a
2478 // concurrent cycle, and those can be nested (i.e., a Full GC can
2479 // interrupt a concurrent cycle), the number of full collections
2480 // completed should be either one (in the case where there was no
2481 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2482 // behind the number of full collections started.
2483
2484 // This is the case for the inner caller, i.e. a Full GC.
2485 assert(concurrent ||
2486 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2487 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2488 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2489 "is inconsistent with _old_marking_cycles_completed = %u",
2490 _old_marking_cycles_started, _old_marking_cycles_completed));
2491
2492 // This is the case for the outer caller, i.e. the concurrent cycle.
2493 assert(!concurrent ||
2494 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2495 err_msg("for outer caller (concurrent cycle): "
2496 "_old_marking_cycles_started = %u "
2497 "is inconsistent with _old_marking_cycles_completed = %u",
2498 _old_marking_cycles_started, _old_marking_cycles_completed));
2499
2500 _old_marking_cycles_completed += 1;
2501
2502 // We need to clear the "in_progress" flag in the CM thread before
2503 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2504 // is set) so that if a waiter requests another System.gc() it doesn't
2505 // incorrectly see that a marking cycle is still in progress.
2506 if (concurrent) {
2507 _cmThread->clear_in_progress();
2508 }
2509
2510 // This notify_all() will ensure that a thread that called
2511 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2512 // and it's waiting for a full GC to finish will be woken up. It is
2513 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2514 FullGCCount_lock->notify_all();
2515 }
2516
2517 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2518 _concurrent_cycle_started = true;
2519 _gc_timer_cm->register_gc_start(start_time);
2520
2521 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2522 trace_heap_before_gc(_gc_tracer_cm);
2523 }
2524
2525 void G1CollectedHeap::register_concurrent_cycle_end() {
2526 if (_concurrent_cycle_started) {
2527 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2528
2529 if (_cm->has_aborted()) {
2530 _gc_tracer_cm->report_concurrent_mode_failure();
2531 }
2532 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2533
2534 _concurrent_cycle_started = false;
2535 }
2536 }
2537
2538 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2539 if (_concurrent_cycle_started) {
2540 trace_heap_after_gc(_gc_tracer_cm);
2541 }
2542 }
2543
2544 G1YCType G1CollectedHeap::yc_type() {
2545 bool is_young = g1_policy()->gcs_are_young();
2546 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2547 bool is_during_mark = mark_in_progress();
2548
2549 if (is_initial_mark) {
2550 return InitialMark;
2551 } else if (is_during_mark) {
2552 return DuringMark;
2553 } else if (is_young) {
2554 return Normal;
2555 } else {
2556 return Mixed;
2557 }
2558 }
2559
2560 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2561 assert_at_safepoint(true /* should_be_vm_thread */);
2562 GCCauseSetter gcs(this, cause);
2563 switch (cause) {
2564 case GCCause::_heap_inspection:
2565 case GCCause::_heap_dump: {
2566 HandleMark hm;
2567 do_full_collection(false); // don't clear all soft refs
2568 break;
2569 }
2570 default: // XXX FIX ME
2571 ShouldNotReachHere(); // Unexpected use of this function
2572 }
2573 }
2574
2575 void G1CollectedHeap::collect(GCCause::Cause cause) {
2576 assert_heap_not_locked();
2577
2578 unsigned int gc_count_before;
2579 unsigned int old_marking_count_before;
2580 bool retry_gc;
2581
2582 do {
2583 retry_gc = false;
2584
2585 {
2586 MutexLocker ml(Heap_lock);
2587
2588 // Read the GC count while holding the Heap_lock
2589 gc_count_before = total_collections();
2590 old_marking_count_before = _old_marking_cycles_started;
2591 }
2592
2593 if (should_do_concurrent_full_gc(cause)) {
2594 // Schedule an initial-mark evacuation pause that will start a
2595 // concurrent cycle. We're setting word_size to 0 which means that
2596 // we are not requesting a post-GC allocation.
2597 VM_G1IncCollectionPause op(gc_count_before,
2598 0, /* word_size */
2599 true, /* should_initiate_conc_mark */
2600 g1_policy()->max_pause_time_ms(),
2601 cause);
2602
2603 VMThread::execute(&op);
2604 if (!op.pause_succeeded()) {
2605 if (old_marking_count_before == _old_marking_cycles_started) {
2606 retry_gc = op.should_retry_gc();
2607 } else {
2608 // A Full GC happened while we were trying to schedule the
2609 // initial-mark GC. No point in starting a new cycle given
2610 // that the whole heap was collected anyway.
2611 }
2612
2613 if (retry_gc) {
2614 if (GC_locker::is_active_and_needs_gc()) {
2615 GC_locker::stall_until_clear();
2616 }
2617 }
2618 }
2619 } else {
2620 if (cause == GCCause::_gc_locker
2621 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2622
2623 // Schedule a standard evacuation pause. We're setting word_size
2624 // to 0 which means that we are not requesting a post-GC allocation.
2625 VM_G1IncCollectionPause op(gc_count_before,
2626 0, /* word_size */
2627 false, /* should_initiate_conc_mark */
2628 g1_policy()->max_pause_time_ms(),
2629 cause);
2630 VMThread::execute(&op);
2631 } else {
2632 // Schedule a Full GC.
2633 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2634 VMThread::execute(&op);
2635 }
2636 }
2637 } while (retry_gc);
2638 }
2639
2640 bool G1CollectedHeap::is_in(const void* p) const {
2641 if (_g1_committed.contains(p)) {
2642 // Given that we know that p is in the committed space,
2643 // heap_region_containing_raw() should successfully
2644 // return the containing region.
2645 HeapRegion* hr = heap_region_containing_raw(p);
2646 return hr->is_in(p);
2647 } else {
2648 return _perm_gen->as_gen()->is_in(p);
2649 }
2650 }
2651
2652 // Iteration functions.
2653
2654 // Iterates an OopClosure over all ref-containing fields of objects
2655 // within a HeapRegion.
2656
2657 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2658 MemRegion _mr;
2659 OopClosure* _cl;
2660 public:
2661 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2662 : _mr(mr), _cl(cl) {}
2663 bool doHeapRegion(HeapRegion* r) {
2664 if (!r->continuesHumongous()) {
2665 r->oop_iterate(_cl);
2666 }
2667 return false;
2668 }
2669 };
2670
2671 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2672 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2673 heap_region_iterate(&blk);
2674 if (do_perm) {
2675 perm_gen()->oop_iterate(cl);
2676 }
2677 }
2678
2679 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2680 IterateOopClosureRegionClosure blk(mr, cl);
2681 heap_region_iterate(&blk);
2682 if (do_perm) {
2683 perm_gen()->oop_iterate(cl);
2684 }
2685 }
2686
2687 // Iterates an ObjectClosure over all objects within a HeapRegion.
2688
2689 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2690 ObjectClosure* _cl;
2691 public:
2692 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2693 bool doHeapRegion(HeapRegion* r) {
2694 if (! r->continuesHumongous()) {
2695 r->object_iterate(_cl);
2696 }
2697 return false;
2698 }
2699 };
2700
2701 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2702 IterateObjectClosureRegionClosure blk(cl);
2703 heap_region_iterate(&blk);
2704 if (do_perm) {
2705 perm_gen()->object_iterate(cl);
2706 }
2707 }
2708
2709 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2710 // FIXME: is this right?
2711 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2712 }
2713
2714 // Calls a SpaceClosure on a HeapRegion.
2715
2716 class SpaceClosureRegionClosure: public HeapRegionClosure {
2717 SpaceClosure* _cl;
2718 public:
2719 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2720 bool doHeapRegion(HeapRegion* r) {
2721 _cl->do_space(r);
2722 return false;
2723 }
2724 };
2725
2726 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2727 SpaceClosureRegionClosure blk(cl);
2728 heap_region_iterate(&blk);
2729 }
2730
2731 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2732 _hrs.iterate(cl);
2733 }
2734
2735 void
2736 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2737 uint worker_id,
2738 uint no_of_par_workers,
2739 jint claim_value) {
2740 const uint regions = n_regions();
2741 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2742 no_of_par_workers :
2743 1);
2744 assert(UseDynamicNumberOfGCThreads ||
2745 no_of_par_workers == workers()->total_workers(),
2746 "Non dynamic should use fixed number of workers");
2747 // try to spread out the starting points of the workers
2748 const HeapRegion* start_hr =
2749 start_region_for_worker(worker_id, no_of_par_workers);
2750 const uint start_index = start_hr->hrs_index();
2751
2752 // each worker will actually look at all regions
2753 for (uint count = 0; count < regions; ++count) {
2754 const uint index = (start_index + count) % regions;
2755 assert(0 <= index && index < regions, "sanity");
2756 HeapRegion* r = region_at(index);
2757 // we'll ignore "continues humongous" regions (we'll process them
2758 // when we come across their corresponding "start humongous"
2759 // region) and regions already claimed
2760 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2761 continue;
2762 }
2763 // OK, try to claim it
2764 if (r->claimHeapRegion(claim_value)) {
2765 // success!
2766 assert(!r->continuesHumongous(), "sanity");
2767 if (r->startsHumongous()) {
2768 // If the region is "starts humongous" we'll iterate over its
2769 // "continues humongous" first; in fact we'll do them
2770 // first. The order is important. In on case, calling the
2771 // closure on the "starts humongous" region might de-allocate
2772 // and clear all its "continues humongous" regions and, as a
2773 // result, we might end up processing them twice. So, we'll do
2774 // them first (notice: most closures will ignore them anyway) and
2775 // then we'll do the "starts humongous" region.
2776 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2777 HeapRegion* chr = region_at(ch_index);
2778
2779 // if the region has already been claimed or it's not
2780 // "continues humongous" we're done
2781 if (chr->claim_value() == claim_value ||
2782 !chr->continuesHumongous()) {
2783 break;
2784 }
2785
2786 // Noone should have claimed it directly. We can given
2787 // that we claimed its "starts humongous" region.
2788 assert(chr->claim_value() != claim_value, "sanity");
2789 assert(chr->humongous_start_region() == r, "sanity");
2790
2791 if (chr->claimHeapRegion(claim_value)) {
2792 // we should always be able to claim it; noone else should
2793 // be trying to claim this region
2794
2795 bool res2 = cl->doHeapRegion(chr);
2796 assert(!res2, "Should not abort");
2797
2798 // Right now, this holds (i.e., no closure that actually
2799 // does something with "continues humongous" regions
2800 // clears them). We might have to weaken it in the future,
2801 // but let's leave these two asserts here for extra safety.
2802 assert(chr->continuesHumongous(), "should still be the case");
2803 assert(chr->humongous_start_region() == r, "sanity");
2804 } else {
2805 guarantee(false, "we should not reach here");
2806 }
2807 }
2808 }
2809
2810 assert(!r->continuesHumongous(), "sanity");
2811 bool res = cl->doHeapRegion(r);
2812 assert(!res, "Should not abort");
2813 }
2814 }
2815 }
2816
2817 class ResetClaimValuesClosure: public HeapRegionClosure {
2818 public:
2819 bool doHeapRegion(HeapRegion* r) {
2820 r->set_claim_value(HeapRegion::InitialClaimValue);
2821 return false;
2822 }
2823 };
2824
2825 void G1CollectedHeap::reset_heap_region_claim_values() {
2826 ResetClaimValuesClosure blk;
2827 heap_region_iterate(&blk);
2828 }
2829
2830 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2831 ResetClaimValuesClosure blk;
2832 collection_set_iterate(&blk);
2833 }
2834
2835 #ifdef ASSERT
2836 // This checks whether all regions in the heap have the correct claim
2837 // value. I also piggy-backed on this a check to ensure that the
2838 // humongous_start_region() information on "continues humongous"
2839 // regions is correct.
2840
2841 class CheckClaimValuesClosure : public HeapRegionClosure {
2842 private:
2843 jint _claim_value;
2844 uint _failures;
2845 HeapRegion* _sh_region;
2846
2847 public:
2848 CheckClaimValuesClosure(jint claim_value) :
2849 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2850 bool doHeapRegion(HeapRegion* r) {
2851 if (r->claim_value() != _claim_value) {
2852 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2853 "claim value = %d, should be %d",
2854 HR_FORMAT_PARAMS(r),
2855 r->claim_value(), _claim_value);
2856 ++_failures;
2857 }
2858 if (!r->isHumongous()) {
2859 _sh_region = NULL;
2860 } else if (r->startsHumongous()) {
2861 _sh_region = r;
2862 } else if (r->continuesHumongous()) {
2863 if (r->humongous_start_region() != _sh_region) {
2864 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2865 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2866 HR_FORMAT_PARAMS(r),
2867 r->humongous_start_region(),
2868 _sh_region);
2869 ++_failures;
2870 }
2871 }
2872 return false;
2873 }
2874 uint failures() { return _failures; }
2875 };
2876
2877 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2878 CheckClaimValuesClosure cl(claim_value);
2879 heap_region_iterate(&cl);
2880 return cl.failures() == 0;
2881 }
2882
2883 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2884 private:
2885 jint _claim_value;
2886 uint _failures;
2887
2888 public:
2889 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2890 _claim_value(claim_value), _failures(0) { }
2891
2892 uint failures() { return _failures; }
2893
2894 bool doHeapRegion(HeapRegion* hr) {
2895 assert(hr->in_collection_set(), "how?");
2896 assert(!hr->isHumongous(), "H-region in CSet");
2897 if (hr->claim_value() != _claim_value) {
2898 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2899 "claim value = %d, should be %d",
2900 HR_FORMAT_PARAMS(hr),
2901 hr->claim_value(), _claim_value);
2902 _failures += 1;
2903 }
2904 return false;
2905 }
2906 };
2907
2908 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2909 CheckClaimValuesInCSetHRClosure cl(claim_value);
2910 collection_set_iterate(&cl);
2911 return cl.failures() == 0;
2912 }
2913 #endif // ASSERT
2914
2915 // Clear the cached CSet starting regions and (more importantly)
2916 // the time stamps. Called when we reset the GC time stamp.
2917 void G1CollectedHeap::clear_cset_start_regions() {
2918 assert(_worker_cset_start_region != NULL, "sanity");
2919 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2920
2921 int n_queues = MAX2((int)ParallelGCThreads, 1);
2922 for (int i = 0; i < n_queues; i++) {
2923 _worker_cset_start_region[i] = NULL;
2924 _worker_cset_start_region_time_stamp[i] = 0;
2925 }
2926 }
2927
2928 // Given the id of a worker, obtain or calculate a suitable
2929 // starting region for iterating over the current collection set.
2930 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2931 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2932
2933 HeapRegion* result = NULL;
2934 unsigned gc_time_stamp = get_gc_time_stamp();
2935
2936 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2937 // Cached starting region for current worker was set
2938 // during the current pause - so it's valid.
2939 // Note: the cached starting heap region may be NULL
2940 // (when the collection set is empty).
2941 result = _worker_cset_start_region[worker_i];
2942 assert(result == NULL || result->in_collection_set(), "sanity");
2943 return result;
2944 }
2945
2946 // The cached entry was not valid so let's calculate
2947 // a suitable starting heap region for this worker.
2948
2949 // We want the parallel threads to start their collection
2950 // set iteration at different collection set regions to
2951 // avoid contention.
2952 // If we have:
2953 // n collection set regions
2954 // p threads
2955 // Then thread t will start at region floor ((t * n) / p)
2956
2957 result = g1_policy()->collection_set();
2958 if (G1CollectedHeap::use_parallel_gc_threads()) {
2959 uint cs_size = g1_policy()->cset_region_length();
2960 uint active_workers = workers()->active_workers();
2961 assert(UseDynamicNumberOfGCThreads ||
2962 active_workers == workers()->total_workers(),
2963 "Unless dynamic should use total workers");
2964
2965 uint end_ind = (cs_size * worker_i) / active_workers;
2966 uint start_ind = 0;
2967
2968 if (worker_i > 0 &&
2969 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2970 // Previous workers starting region is valid
2971 // so let's iterate from there
2972 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2973 result = _worker_cset_start_region[worker_i - 1];
2974 }
2975
2976 for (uint i = start_ind; i < end_ind; i++) {
2977 result = result->next_in_collection_set();
2978 }
2979 }
2980
2981 // Note: the calculated starting heap region may be NULL
2982 // (when the collection set is empty).
2983 assert(result == NULL || result->in_collection_set(), "sanity");
2984 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2985 "should be updated only once per pause");
2986 _worker_cset_start_region[worker_i] = result;
2987 OrderAccess::storestore();
2988 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2989 return result;
2990 }
2991
2992 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2993 uint no_of_par_workers) {
2994 uint worker_num =
2995 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2996 assert(UseDynamicNumberOfGCThreads ||
2997 no_of_par_workers == workers()->total_workers(),
2998 "Non dynamic should use fixed number of workers");
2999 const uint start_index = n_regions() * worker_i / worker_num;
3000 return region_at(start_index);
3001 }
3002
3003 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
3004 HeapRegion* r = g1_policy()->collection_set();
3005 while (r != NULL) {
3006 HeapRegion* next = r->next_in_collection_set();
3007 if (cl->doHeapRegion(r)) {
3008 cl->incomplete();
3009 return;
3010 }
3011 r = next;
3012 }
3013 }
3014
3015 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
3016 HeapRegionClosure *cl) {
3017 if (r == NULL) {
3018 // The CSet is empty so there's nothing to do.
3019 return;
3020 }
3021
3022 assert(r->in_collection_set(),
3023 "Start region must be a member of the collection set.");
3024 HeapRegion* cur = r;
3025 while (cur != NULL) {
3026 HeapRegion* next = cur->next_in_collection_set();
3027 if (cl->doHeapRegion(cur) && false) {
3028 cl->incomplete();
3029 return;
3030 }
3031 cur = next;
3032 }
3033 cur = g1_policy()->collection_set();
3034 while (cur != r) {
3035 HeapRegion* next = cur->next_in_collection_set();
3036 if (cl->doHeapRegion(cur) && false) {
3037 cl->incomplete();
3038 return;
3039 }
3040 cur = next;
3041 }
3042 }
3043
3044 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
3045 return n_regions() > 0 ? region_at(0) : NULL;
3046 }
3047
3048
3049 Space* G1CollectedHeap::space_containing(const void* addr) const {
3050 Space* res = heap_region_containing(addr);
3051 if (res == NULL)
3052 res = perm_gen()->space_containing(addr);
3053 return res;
3054 }
3055
3056 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
3057 Space* sp = space_containing(addr);
3058 if (sp != NULL) {
3059 return sp->block_start(addr);
3060 }
3061 return NULL;
3062 }
3063
3064 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3065 Space* sp = space_containing(addr);
3066 assert(sp != NULL, "block_size of address outside of heap");
3067 return sp->block_size(addr);
3068 }
3069
3070 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3071 Space* sp = space_containing(addr);
3072 return sp->block_is_obj(addr);
3073 }
3074
3075 bool G1CollectedHeap::supports_tlab_allocation() const {
3076 return true;
3077 }
3078
3079 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3080 return HeapRegion::GrainBytes;
3081 }
3082
3083 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3084 // Return the remaining space in the cur alloc region, but not less than
3085 // the min TLAB size.
3086
3087 // Also, this value can be at most the humongous object threshold,
3088 // since we can't allow tlabs to grow big enough to accommodate
3089 // humongous objects.
3090
3091 HeapRegion* hr = _mutator_alloc_region.get();
3092 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3093 if (hr == NULL) {
3094 return max_tlab_size;
3095 } else {
3096 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3097 }
3098 }
3099
3100 size_t G1CollectedHeap::max_capacity() const {
3101 return _g1_reserved.byte_size();
3102 }
3103
3104 jlong G1CollectedHeap::millis_since_last_gc() {
3105 // assert(false, "NYI");
3106 return 0;
3107 }
3108
3109 void G1CollectedHeap::prepare_for_verify() {
3110 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3111 ensure_parsability(false);
3112 }
3113 g1_rem_set()->prepare_for_verify();
3114 }
3115
3116 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3117 VerifyOption vo) {
3118 switch (vo) {
3119 case VerifyOption_G1UsePrevMarking:
3120 return hr->obj_allocated_since_prev_marking(obj);
3121 case VerifyOption_G1UseNextMarking:
3122 return hr->obj_allocated_since_next_marking(obj);
3123 case VerifyOption_G1UseMarkWord:
3124 return false;
3125 default:
3126 ShouldNotReachHere();
3127 }
3128 return false; // keep some compilers happy
3129 }
3130
3131 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3132 switch (vo) {
3133 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3134 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3135 case VerifyOption_G1UseMarkWord: return NULL;
3136 default: ShouldNotReachHere();
3137 }
3138 return NULL; // keep some compilers happy
3139 }
3140
3141 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3142 switch (vo) {
3143 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3144 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3145 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3146 default: ShouldNotReachHere();
3147 }
3148 return false; // keep some compilers happy
3149 }
3150
3151 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3152 switch (vo) {
3153 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3154 case VerifyOption_G1UseNextMarking: return "NTAMS";
3155 case VerifyOption_G1UseMarkWord: return "NONE";
3156 default: ShouldNotReachHere();
3157 }
3158 return NULL; // keep some compilers happy
3159 }
3160
3161 class VerifyLivenessOopClosure: public OopClosure {
3162 G1CollectedHeap* _g1h;
3163 VerifyOption _vo;
3164 public:
3165 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3166 _g1h(g1h), _vo(vo)
3167 { }
3168 void do_oop(narrowOop *p) { do_oop_work(p); }
3169 void do_oop( oop *p) { do_oop_work(p); }
3170
3171 template <class T> void do_oop_work(T *p) {
3172 oop obj = oopDesc::load_decode_heap_oop(p);
3173 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3174 "Dead object referenced by a not dead object");
3175 }
3176 };
3177
3178 class VerifyObjsInRegionClosure: public ObjectClosure {
3179 private:
3180 G1CollectedHeap* _g1h;
3181 size_t _live_bytes;
3182 HeapRegion *_hr;
3183 VerifyOption _vo;
3184 public:
3185 // _vo == UsePrevMarking -> use "prev" marking information,
3186 // _vo == UseNextMarking -> use "next" marking information,
3187 // _vo == UseMarkWord -> use mark word from object header.
3188 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3189 : _live_bytes(0), _hr(hr), _vo(vo) {
3190 _g1h = G1CollectedHeap::heap();
3191 }
3192 void do_object(oop o) {
3193 VerifyLivenessOopClosure isLive(_g1h, _vo);
3194 assert(o != NULL, "Huh?");
3195 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3196 // If the object is alive according to the mark word,
3197 // then verify that the marking information agrees.
3198 // Note we can't verify the contra-positive of the
3199 // above: if the object is dead (according to the mark
3200 // word), it may not be marked, or may have been marked
3201 // but has since became dead, or may have been allocated
3202 // since the last marking.
3203 if (_vo == VerifyOption_G1UseMarkWord) {
3204 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3205 }
3206
3207 o->oop_iterate(&isLive);
3208 if (!_hr->obj_allocated_since_prev_marking(o)) {
3209 size_t obj_size = o->size(); // Make sure we don't overflow
3210 _live_bytes += (obj_size * HeapWordSize);
3211 }
3212 }
3213 }
3214 size_t live_bytes() { return _live_bytes; }
3215 };
3216
3217 class PrintObjsInRegionClosure : public ObjectClosure {
3218 HeapRegion *_hr;
3219 G1CollectedHeap *_g1;
3220 public:
3221 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3222 _g1 = G1CollectedHeap::heap();
3223 };
3224
3225 void do_object(oop o) {
3226 if (o != NULL) {
3227 HeapWord *start = (HeapWord *) o;
3228 size_t word_sz = o->size();
3229 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3230 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3231 (void*) o, word_sz,
3232 _g1->isMarkedPrev(o),
3233 _g1->isMarkedNext(o),
3234 _hr->obj_allocated_since_prev_marking(o));
3235 HeapWord *end = start + word_sz;
3236 HeapWord *cur;
3237 int *val;
3238 for (cur = start; cur < end; cur++) {
3239 val = (int *) cur;
3240 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3241 }
3242 }
3243 }
3244 };
3245
3246 class VerifyRegionClosure: public HeapRegionClosure {
3247 private:
3248 bool _par;
3249 VerifyOption _vo;
3250 bool _failures;
3251 public:
3252 // _vo == UsePrevMarking -> use "prev" marking information,
3253 // _vo == UseNextMarking -> use "next" marking information,
3254 // _vo == UseMarkWord -> use mark word from object header.
3255 VerifyRegionClosure(bool par, VerifyOption vo)
3256 : _par(par),
3257 _vo(vo),
3258 _failures(false) {}
3259
3260 bool failures() {
3261 return _failures;
3262 }
3263
3264 bool doHeapRegion(HeapRegion* r) {
3265 if (!r->continuesHumongous()) {
3266 bool failures = false;
3267 r->verify(_vo, &failures);
3268 if (failures) {
3269 _failures = true;
3270 } else {
3271 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3272 r->object_iterate(¬_dead_yet_cl);
3273 if (_vo != VerifyOption_G1UseNextMarking) {
3274 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3275 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3276 "max_live_bytes "SIZE_FORMAT" "
3277 "< calculated "SIZE_FORMAT,
3278 r->bottom(), r->end(),
3279 r->max_live_bytes(),
3280 not_dead_yet_cl.live_bytes());
3281 _failures = true;
3282 }
3283 } else {
3284 // When vo == UseNextMarking we cannot currently do a sanity
3285 // check on the live bytes as the calculation has not been
3286 // finalized yet.
3287 }
3288 }
3289 }
3290 return false; // stop the region iteration if we hit a failure
3291 }
3292 };
3293
3294 class VerifyRootsClosure: public OopsInGenClosure {
3295 private:
3296 G1CollectedHeap* _g1h;
3297 VerifyOption _vo;
3298 bool _failures;
3299 public:
3300 // _vo == UsePrevMarking -> use "prev" marking information,
3301 // _vo == UseNextMarking -> use "next" marking information,
3302 // _vo == UseMarkWord -> use mark word from object header.
3303 VerifyRootsClosure(VerifyOption vo) :
3304 _g1h(G1CollectedHeap::heap()),
3305 _vo(vo),
3306 _failures(false) { }
3307
3308 bool failures() { return _failures; }
3309
3310 template <class T> void do_oop_nv(T* p) {
3311 T heap_oop = oopDesc::load_heap_oop(p);
3312 if (!oopDesc::is_null(heap_oop)) {
3313 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3314 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3315 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3316 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3317 if (_vo == VerifyOption_G1UseMarkWord) {
3318 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3319 }
3320 obj->print_on(gclog_or_tty);
3321 _failures = true;
3322 }
3323 }
3324 }
3325
3326 void do_oop(oop* p) { do_oop_nv(p); }
3327 void do_oop(narrowOop* p) { do_oop_nv(p); }
3328 };
3329
3330 // This is the task used for parallel heap verification.
3331
3332 class G1ParVerifyTask: public AbstractGangTask {
3333 private:
3334 G1CollectedHeap* _g1h;
3335 VerifyOption _vo;
3336 bool _failures;
3337
3338 public:
3339 // _vo == UsePrevMarking -> use "prev" marking information,
3340 // _vo == UseNextMarking -> use "next" marking information,
3341 // _vo == UseMarkWord -> use mark word from object header.
3342 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3343 AbstractGangTask("Parallel verify task"),
3344 _g1h(g1h),
3345 _vo(vo),
3346 _failures(false) { }
3347
3348 bool failures() {
3349 return _failures;
3350 }
3351
3352 void work(uint worker_id) {
3353 HandleMark hm;
3354 VerifyRegionClosure blk(true, _vo);
3355 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3356 _g1h->workers()->active_workers(),
3357 HeapRegion::ParVerifyClaimValue);
3358 if (blk.failures()) {
3359 _failures = true;
3360 }
3361 }
3362 };
3363
3364 void G1CollectedHeap::verify(bool silent) {
3365 verify(silent, VerifyOption_G1UsePrevMarking);
3366 }
3367
3368 void G1CollectedHeap::verify(bool silent,
3369 VerifyOption vo) {
3370 if (SafepointSynchronize::is_at_safepoint()) {
3371 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3372 VerifyRootsClosure rootsCl(vo);
3373
3374 assert(Thread::current()->is_VM_thread(),
3375 "Expected to be executed serially by the VM thread at this point");
3376
3377 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3378
3379 // We apply the relevant closures to all the oops in the
3380 // system dictionary, the string table and the code cache.
3381 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3382
3383 process_strong_roots(true, // activate StrongRootsScope
3384 true, // we set "collecting perm gen" to true,
3385 // so we don't reset the dirty cards in the perm gen.
3386 ScanningOption(so), // roots scanning options
3387 &rootsCl,
3388 &blobsCl,
3389 &rootsCl);
3390
3391 // If we're verifying after the marking phase of a Full GC then we can't
3392 // treat the perm gen as roots into the G1 heap. Some of the objects in
3393 // the perm gen may be dead and hence not marked. If one of these dead
3394 // objects is considered to be a root then we may end up with a false
3395 // "Root location <x> points to dead ob <y>" failure.
3396 if (vo != VerifyOption_G1UseMarkWord) {
3397 // Since we used "collecting_perm_gen" == true above, we will not have
3398 // checked the refs from perm into the G1-collected heap. We check those
3399 // references explicitly below. Whether the relevant cards are dirty
3400 // is checked further below in the rem set verification.
3401 if (!silent) { gclog_or_tty->print("Permgen roots "); }
3402 perm_gen()->oop_iterate(&rootsCl);
3403 }
3404 bool failures = rootsCl.failures();
3405
3406 if (vo != VerifyOption_G1UseMarkWord) {
3407 // If we're verifying during a full GC then the region sets
3408 // will have been torn down at the start of the GC. Therefore
3409 // verifying the region sets will fail. So we only verify
3410 // the region sets when not in a full GC.
3411 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3412 verify_region_sets();
3413 }
3414
3415 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3416 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3417 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3418 "sanity check");
3419
3420 G1ParVerifyTask task(this, vo);
3421 assert(UseDynamicNumberOfGCThreads ||
3422 workers()->active_workers() == workers()->total_workers(),
3423 "If not dynamic should be using all the workers");
3424 int n_workers = workers()->active_workers();
3425 set_par_threads(n_workers);
3426 workers()->run_task(&task);
3427 set_par_threads(0);
3428 if (task.failures()) {
3429 failures = true;
3430 }
3431
3432 // Checks that the expected amount of parallel work was done.
3433 // The implication is that n_workers is > 0.
3434 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3435 "sanity check");
3436
3437 reset_heap_region_claim_values();
3438
3439 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3440 "sanity check");
3441 } else {
3442 VerifyRegionClosure blk(false, vo);
3443 heap_region_iterate(&blk);
3444 if (blk.failures()) {
3445 failures = true;
3446 }
3447 }
3448 if (!silent) gclog_or_tty->print("RemSet ");
3449 rem_set()->verify();
3450
3451 if (failures) {
3452 gclog_or_tty->print_cr("Heap:");
3453 // It helps to have the per-region information in the output to
3454 // help us track down what went wrong. This is why we call
3455 // print_extended_on() instead of print_on().
3456 print_extended_on(gclog_or_tty);
3457 gclog_or_tty->print_cr("");
3458 #ifndef PRODUCT
3459 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3460 concurrent_mark()->print_reachable("at-verification-failure",
3461 vo, false /* all */);
3462 }
3463 #endif
3464 gclog_or_tty->flush();
3465 }
3466 guarantee(!failures, "there should not have been any failures");
3467 } else {
3468 if (!silent)
3469 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3470 }
3471 }
3472
3473 class PrintRegionClosure: public HeapRegionClosure {
3474 outputStream* _st;
3475 public:
3476 PrintRegionClosure(outputStream* st) : _st(st) {}
3477 bool doHeapRegion(HeapRegion* r) {
3478 r->print_on(_st);
3479 return false;
3480 }
3481 };
3482
3483 void G1CollectedHeap::print_on(outputStream* st) const {
3484 st->print(" %-20s", "garbage-first heap");
3485 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3486 capacity()/K, used_unlocked()/K);
3487 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3488 _g1_storage.low_boundary(),
3489 _g1_storage.high(),
3490 _g1_storage.high_boundary());
3491 st->cr();
3492 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3493 uint young_regions = _young_list->length();
3494 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3495 (size_t) young_regions * HeapRegion::GrainBytes / K);
3496 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3497 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3498 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3499 st->cr();
3500 perm()->as_gen()->print_on(st);
3501 }
3502
3503 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3504 print_on(st);
3505
3506 // Print the per-region information.
3507 st->cr();
3508 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3509 "HS=humongous(starts), HC=humongous(continues), "
3510 "CS=collection set, F=free, TS=gc time stamp, "
3511 "PTAMS=previous top-at-mark-start, "
3512 "NTAMS=next top-at-mark-start)");
3513 PrintRegionClosure blk(st);
3514 heap_region_iterate(&blk);
3515 }
3516
3517 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3518 if (G1CollectedHeap::use_parallel_gc_threads()) {
3519 workers()->print_worker_threads_on(st);
3520 }
3521 _cmThread->print_on(st);
3522 st->cr();
3523 _cm->print_worker_threads_on(st);
3524 _cg1r->print_worker_threads_on(st);
3525 st->cr();
3526 }
3527
3528 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3529 if (G1CollectedHeap::use_parallel_gc_threads()) {
3530 workers()->threads_do(tc);
3531 }
3532 tc->do_thread(_cmThread);
3533 _cg1r->threads_do(tc);
3534 }
3535
3536 void G1CollectedHeap::print_tracing_info() const {
3537 // We'll overload this to mean "trace GC pause statistics."
3538 if (TraceGen0Time || TraceGen1Time) {
3539 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3540 // to that.
3541 g1_policy()->print_tracing_info();
3542 }
3543 if (G1SummarizeRSetStats) {
3544 g1_rem_set()->print_summary_info();
3545 }
3546 if (G1SummarizeConcMark) {
3547 concurrent_mark()->print_summary_info();
3548 }
3549 g1_policy()->print_yg_surv_rate_info();
3550 SpecializationStats::print();
3551 }
3552
3553 #ifndef PRODUCT
3554 // Helpful for debugging RSet issues.
3555
3556 class PrintRSetsClosure : public HeapRegionClosure {
3557 private:
3558 const char* _msg;
3559 size_t _occupied_sum;
3560
3561 public:
3562 bool doHeapRegion(HeapRegion* r) {
3563 HeapRegionRemSet* hrrs = r->rem_set();
3564 size_t occupied = hrrs->occupied();
3565 _occupied_sum += occupied;
3566
3567 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3568 HR_FORMAT_PARAMS(r));
3569 if (occupied == 0) {
3570 gclog_or_tty->print_cr(" RSet is empty");
3571 } else {
3572 hrrs->print();
3573 }
3574 gclog_or_tty->print_cr("----------");
3575 return false;
3576 }
3577
3578 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3579 gclog_or_tty->cr();
3580 gclog_or_tty->print_cr("========================================");
3581 gclog_or_tty->print_cr(msg);
3582 gclog_or_tty->cr();
3583 }
3584
3585 ~PrintRSetsClosure() {
3586 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3587 gclog_or_tty->print_cr("========================================");
3588 gclog_or_tty->cr();
3589 }
3590 };
3591
3592 void G1CollectedHeap::print_cset_rsets() {
3593 PrintRSetsClosure cl("Printing CSet RSets");
3594 collection_set_iterate(&cl);
3595 }
3596
3597 void G1CollectedHeap::print_all_rsets() {
3598 PrintRSetsClosure cl("Printing All RSets");;
3599 heap_region_iterate(&cl);
3600 }
3601 #endif // PRODUCT
3602
3603 G1CollectedHeap* G1CollectedHeap::heap() {
3604 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3605 "not a garbage-first heap");
3606 return _g1h;
3607 }
3608
3609 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3610 // always_do_update_barrier = false;
3611 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3612 // Call allocation profiler
3613 AllocationProfiler::iterate_since_last_gc();
3614 // Fill TLAB's and such
3615 ensure_parsability(true);
3616 }
3617
3618 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3619 // FIXME: what is this about?
3620 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3621 // is set.
3622 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3623 "derived pointer present"));
3624 // always_do_update_barrier = true;
3625
3626 // We have just completed a GC. Update the soft reference
3627 // policy with the new heap occupancy
3628 Universe::update_heap_info_at_gc();
3629 }
3630
3631 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3632 unsigned int gc_count_before,
3633 bool* succeeded) {
3634 assert_heap_not_locked_and_not_at_safepoint();
3635 g1_policy()->record_stop_world_start();
3636 VM_G1IncCollectionPause op(gc_count_before,
3637 word_size,
3638 false, /* should_initiate_conc_mark */
3639 g1_policy()->max_pause_time_ms(),
3640 GCCause::_g1_inc_collection_pause);
3641 VMThread::execute(&op);
3642
3643 HeapWord* result = op.result();
3644 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3645 assert(result == NULL || ret_succeeded,
3646 "the result should be NULL if the VM did not succeed");
3647 *succeeded = ret_succeeded;
3648
3649 assert_heap_not_locked();
3650 return result;
3651 }
3652
3653 void
3654 G1CollectedHeap::doConcurrentMark() {
3655 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3656 if (!_cmThread->in_progress()) {
3657 _cmThread->set_started();
3658 CGC_lock->notify();
3659 }
3660 }
3661
3662 size_t G1CollectedHeap::pending_card_num() {
3663 size_t extra_cards = 0;
3664 JavaThread *curr = Threads::first();
3665 while (curr != NULL) {
3666 DirtyCardQueue& dcq = curr->dirty_card_queue();
3667 extra_cards += dcq.size();
3668 curr = curr->next();
3669 }
3670 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3671 size_t buffer_size = dcqs.buffer_size();
3672 size_t buffer_num = dcqs.completed_buffers_num();
3673
3674 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3675 // in bytes - not the number of 'entries'. We need to convert
3676 // into a number of cards.
3677 return (buffer_size * buffer_num + extra_cards) / oopSize;
3678 }
3679
3680 size_t G1CollectedHeap::cards_scanned() {
3681 return g1_rem_set()->cardsScanned();
3682 }
3683
3684 void
3685 G1CollectedHeap::setup_surviving_young_words() {
3686 assert(_surviving_young_words == NULL, "pre-condition");
3687 uint array_length = g1_policy()->young_cset_region_length();
3688 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3689 if (_surviving_young_words == NULL) {
3690 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3691 "Not enough space for young surv words summary.");
3692 }
3693 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3694 #ifdef ASSERT
3695 for (uint i = 0; i < array_length; ++i) {
3696 assert( _surviving_young_words[i] == 0, "memset above" );
3697 }
3698 #endif // !ASSERT
3699 }
3700
3701 void
3702 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3703 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3704 uint array_length = g1_policy()->young_cset_region_length();
3705 for (uint i = 0; i < array_length; ++i) {
3706 _surviving_young_words[i] += surv_young_words[i];
3707 }
3708 }
3709
3710 void
3711 G1CollectedHeap::cleanup_surviving_young_words() {
3712 guarantee( _surviving_young_words != NULL, "pre-condition" );
3713 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3714 _surviving_young_words = NULL;
3715 }
3716
3717 #ifdef ASSERT
3718 class VerifyCSetClosure: public HeapRegionClosure {
3719 public:
3720 bool doHeapRegion(HeapRegion* hr) {
3721 // Here we check that the CSet region's RSet is ready for parallel
3722 // iteration. The fields that we'll verify are only manipulated
3723 // when the region is part of a CSet and is collected. Afterwards,
3724 // we reset these fields when we clear the region's RSet (when the
3725 // region is freed) so they are ready when the region is
3726 // re-allocated. The only exception to this is if there's an
3727 // evacuation failure and instead of freeing the region we leave
3728 // it in the heap. In that case, we reset these fields during
3729 // evacuation failure handling.
3730 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3731
3732 // Here's a good place to add any other checks we'd like to
3733 // perform on CSet regions.
3734 return false;
3735 }
3736 };
3737 #endif // ASSERT
3738
3739 #if TASKQUEUE_STATS
3740 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3741 st->print_raw_cr("GC Task Stats");
3742 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3743 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3744 }
3745
3746 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3747 print_taskqueue_stats_hdr(st);
3748
3749 TaskQueueStats totals;
3750 const int n = workers() != NULL ? workers()->total_workers() : 1;
3751 for (int i = 0; i < n; ++i) {
3752 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3753 totals += task_queue(i)->stats;
3754 }
3755 st->print_raw("tot "); totals.print(st); st->cr();
3756
3757 DEBUG_ONLY(totals.verify());
3758 }
3759
3760 void G1CollectedHeap::reset_taskqueue_stats() {
3761 const int n = workers() != NULL ? workers()->total_workers() : 1;
3762 for (int i = 0; i < n; ++i) {
3763 task_queue(i)->stats.reset();
3764 }
3765 }
3766 #endif // TASKQUEUE_STATS
3767
3768 void G1CollectedHeap::log_gc_header() {
3769 if (!G1Log::fine()) {
3770 return;
3771 }
3772
3773 gclog_or_tty->date_stamp(PrintGCDateStamps);
3774 gclog_or_tty->stamp(PrintGCTimeStamps);
3775
3776 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3777 .append(g1_policy()->gcs_are_young() ? " (young)" : " (mixed)")
3778 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3779
3780 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3781 }
3782
3783 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3784 if (!G1Log::fine()) {
3785 return;
3786 }
3787
3788 if (G1Log::finer()) {
3789 if (evacuation_failed()) {
3790 gclog_or_tty->print(" (to-space exhausted)");
3791 }
3792 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3793 g1_policy()->phase_times()->note_gc_end();
3794 g1_policy()->phase_times()->print(pause_time_sec);
3795 g1_policy()->print_detailed_heap_transition();
3796 } else {
3797 if (evacuation_failed()) {
3798 gclog_or_tty->print("--");
3799 }
3800 g1_policy()->print_heap_transition();
3801 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3802 }
3803 gclog_or_tty->flush();
3804 }
3805
3806 bool
3807 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3808 assert_at_safepoint(true /* should_be_vm_thread */);
3809 guarantee(!is_gc_active(), "collection is not reentrant");
3810
3811 if (GC_locker::check_active_before_gc()) {
3812 return false;
3813 }
3814
3815 _gc_timer_stw->register_gc_start(os::elapsed_counter());
3816
3817 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3818
3819 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3820 ResourceMark rm;
3821
3822 print_heap_before_gc();
3823 trace_heap_before_gc(_gc_tracer_stw);
3824
3825 HRSPhaseSetter x(HRSPhaseEvacuation);
3826 verify_region_sets_optional();
3827 verify_dirty_young_regions();
3828
3829 // This call will decide whether this pause is an initial-mark
3830 // pause. If it is, during_initial_mark_pause() will return true
3831 // for the duration of this pause.
3832 g1_policy()->decide_on_conc_mark_initiation();
3833
3834 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3835 assert(!g1_policy()->during_initial_mark_pause() ||
3836 g1_policy()->gcs_are_young(), "sanity");
3837
3838 // We also do not allow mixed GCs during marking.
3839 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3840
3841 // Record whether this pause is an initial mark. When the current
3842 // thread has completed its logging output and it's safe to signal
3843 // the CM thread, the flag's value in the policy has been reset.
3844 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3845
3846 // Inner scope for scope based logging, timers, and stats collection
3847 {
3848 EvacuationInfo evacuation_info;
3849
3850 if (g1_policy()->during_initial_mark_pause()) {
3851 // We are about to start a marking cycle, so we increment the
3852 // full collection counter.
3853 increment_old_marking_cycles_started();
3854 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3855 }
3856
3857 _gc_tracer_stw->report_yc_type(yc_type());
3858
3859 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3860
3861 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3862 workers()->active_workers() : 1);
3863 double pause_start_sec = os::elapsedTime();
3864 g1_policy()->phase_times()->note_gc_start(active_workers);
3865 log_gc_header();
3866
3867 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3868 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3869
3870 // If the secondary_free_list is not empty, append it to the
3871 // free_list. No need to wait for the cleanup operation to finish;
3872 // the region allocation code will check the secondary_free_list
3873 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3874 // set, skip this step so that the region allocation code has to
3875 // get entries from the secondary_free_list.
3876 if (!G1StressConcRegionFreeing) {
3877 append_secondary_free_list_if_not_empty_with_lock();
3878 }
3879
3880 assert(check_young_list_well_formed(),
3881 "young list should be well formed");
3882
3883 // Don't dynamically change the number of GC threads this early. A value of
3884 // 0 is used to indicate serial work. When parallel work is done,
3885 // it will be set.
3886
3887 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3888 IsGCActiveMark x;
3889
3890 gc_prologue(false);
3891 increment_total_collections(false /* full gc */);
3892 increment_gc_time_stamp();
3893
3894 verify_before_gc();
3895
3896 COMPILER2_PRESENT(DerivedPointerTable::clear());
3897
3898 // Please see comment in g1CollectedHeap.hpp and
3899 // G1CollectedHeap::ref_processing_init() to see how
3900 // reference processing currently works in G1.
3901
3902 // Enable discovery in the STW reference processor
3903 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3904 true /*verify_no_refs*/);
3905
3906 {
3907 // We want to temporarily turn off discovery by the
3908 // CM ref processor, if necessary, and turn it back on
3909 // on again later if we do. Using a scoped
3910 // NoRefDiscovery object will do this.
3911 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3912
3913 // Forget the current alloc region (we might even choose it to be part
3914 // of the collection set!).
3915 release_mutator_alloc_region();
3916
3917 // We should call this after we retire the mutator alloc
3918 // region(s) so that all the ALLOC / RETIRE events are generated
3919 // before the start GC event.
3920 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3921
3922 // This timing is only used by the ergonomics to handle our pause target.
3923 // It is unclear why this should not include the full pause. We will
3924 // investigate this in CR 7178365.
3925 //
3926 // Preserving the old comment here if that helps the investigation:
3927 //
3928 // The elapsed time induced by the start time below deliberately elides
3929 // the possible verification above.
3930 double sample_start_time_sec = os::elapsedTime();
3931
3932 #if YOUNG_LIST_VERBOSE
3933 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3934 _young_list->print();
3935 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3936 #endif // YOUNG_LIST_VERBOSE
3937
3938 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3939
3940 double scan_wait_start = os::elapsedTime();
3941 // We have to wait until the CM threads finish scanning the
3942 // root regions as it's the only way to ensure that all the
3943 // objects on them have been correctly scanned before we start
3944 // moving them during the GC.
3945 bool waited = _cm->root_regions()->wait_until_scan_finished();
3946 double wait_time_ms = 0.0;
3947 if (waited) {
3948 double scan_wait_end = os::elapsedTime();
3949 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3950 }
3951 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3952
3953 #if YOUNG_LIST_VERBOSE
3954 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3955 _young_list->print();
3956 #endif // YOUNG_LIST_VERBOSE
3957
3958 if (g1_policy()->during_initial_mark_pause()) {
3959 concurrent_mark()->checkpointRootsInitialPre();
3960 }
3961 perm_gen()->save_marks();
3962
3963 #if YOUNG_LIST_VERBOSE
3964 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3965 _young_list->print();
3966 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3967 #endif // YOUNG_LIST_VERBOSE
3968
3969 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3970
3971 _cm->note_start_of_gc();
3972 // We should not verify the per-thread SATB buffers given that
3973 // we have not filtered them yet (we'll do so during the
3974 // GC). We also call this after finalize_cset() to
3975 // ensure that the CSet has been finalized.
3976 _cm->verify_no_cset_oops(true /* verify_stacks */,
3977 true /* verify_enqueued_buffers */,
3978 false /* verify_thread_buffers */,
3979 true /* verify_fingers */);
3980
3981 if (_hr_printer.is_active()) {
3982 HeapRegion* hr = g1_policy()->collection_set();
3983 while (hr != NULL) {
3984 G1HRPrinter::RegionType type;
3985 if (!hr->is_young()) {
3986 type = G1HRPrinter::Old;
3987 } else if (hr->is_survivor()) {
3988 type = G1HRPrinter::Survivor;
3989 } else {
3990 type = G1HRPrinter::Eden;
3991 }
3992 _hr_printer.cset(hr);
3993 hr = hr->next_in_collection_set();
3994 }
3995 }
3996
3997 #ifdef ASSERT
3998 VerifyCSetClosure cl;
3999 collection_set_iterate(&cl);
4000 #endif // ASSERT
4001
4002 setup_surviving_young_words();
4003
4004 // Initialize the GC alloc regions.
4005 init_gc_alloc_regions(evacuation_info);
4006
4007 // Actually do the work...
4008 evacuate_collection_set(evacuation_info);
4009
4010 // We do this to mainly verify the per-thread SATB buffers
4011 // (which have been filtered by now) since we didn't verify
4012 // them earlier. No point in re-checking the stacks / enqueued
4013 // buffers given that the CSet has not changed since last time
4014 // we checked.
4015 _cm->verify_no_cset_oops(false /* verify_stacks */,
4016 false /* verify_enqueued_buffers */,
4017 true /* verify_thread_buffers */,
4018 true /* verify_fingers */);
4019
4020 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4021 g1_policy()->clear_collection_set();
4022
4023 cleanup_surviving_young_words();
4024
4025 // Start a new incremental collection set for the next pause.
4026 g1_policy()->start_incremental_cset_building();
4027
4028 // Clear the _cset_fast_test bitmap in anticipation of adding
4029 // regions to the incremental collection set for the next
4030 // evacuation pause.
4031 clear_cset_fast_test();
4032
4033 _young_list->reset_sampled_info();
4034
4035 // Don't check the whole heap at this point as the
4036 // GC alloc regions from this pause have been tagged
4037 // as survivors and moved on to the survivor list.
4038 // Survivor regions will fail the !is_young() check.
4039 assert(check_young_list_empty(false /* check_heap */),
4040 "young list should be empty");
4041
4042 #if YOUNG_LIST_VERBOSE
4043 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4044 _young_list->print();
4045 #endif // YOUNG_LIST_VERBOSE
4046
4047 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4048 _young_list->first_survivor_region(),
4049 _young_list->last_survivor_region());
4050
4051 _young_list->reset_auxilary_lists();
4052
4053 if (evacuation_failed()) {
4054 _summary_bytes_used = recalculate_used();
4055 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4056 for (uint i = 0; i < n_queues; i++) {
4057 if (_evacuation_failed_info_array[i].has_failed()) {
4058 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4059 }
4060 }
4061 } else {
4062 // The "used" of the the collection set have already been subtracted
4063 // when they were freed. Add in the bytes evacuated.
4064 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4065 }
4066
4067 if (g1_policy()->during_initial_mark_pause()) {
4068 // We have to do this before we notify the CM threads that
4069 // they can start working to make sure that all the
4070 // appropriate initialization is done on the CM object.
4071 concurrent_mark()->checkpointRootsInitialPost();
4072 set_marking_started();
4073 // Note that we don't actually trigger the CM thread at
4074 // this point. We do that later when we're sure that
4075 // the current thread has completed its logging output.
4076 }
4077
4078 allocate_dummy_regions();
4079
4080 #if YOUNG_LIST_VERBOSE
4081 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4082 _young_list->print();
4083 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4084 #endif // YOUNG_LIST_VERBOSE
4085
4086 init_mutator_alloc_region();
4087
4088 {
4089 size_t expand_bytes = g1_policy()->expansion_amount();
4090 if (expand_bytes > 0) {
4091 size_t bytes_before = capacity();
4092 // No need for an ergo verbose message here,
4093 // expansion_amount() does this when it returns a value > 0.
4094 if (!expand(expand_bytes)) {
4095 // We failed to expand the heap so let's verify that
4096 // committed/uncommitted amount match the backing store
4097 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4098 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4099 }
4100 }
4101 }
4102
4103 // We redo the verification but now wrt to the new CSet which
4104 // has just got initialized after the previous CSet was freed.
4105 _cm->verify_no_cset_oops(true /* verify_stacks */,
4106 true /* verify_enqueued_buffers */,
4107 true /* verify_thread_buffers */,
4108 true /* verify_fingers */);
4109 _cm->note_end_of_gc();
4110
4111 // This timing is only used by the ergonomics to handle our pause target.
4112 // It is unclear why this should not include the full pause. We will
4113 // investigate this in CR 7178365.
4114 double sample_end_time_sec = os::elapsedTime();
4115 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4116 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4117
4118 MemoryService::track_memory_usage();
4119
4120 // In prepare_for_verify() below we'll need to scan the deferred
4121 // update buffers to bring the RSets up-to-date if
4122 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4123 // the update buffers we'll probably need to scan cards on the
4124 // regions we just allocated to (i.e., the GC alloc
4125 // regions). However, during the last GC we called
4126 // set_saved_mark() on all the GC alloc regions, so card
4127 // scanning might skip the [saved_mark_word()...top()] area of
4128 // those regions (i.e., the area we allocated objects into
4129 // during the last GC). But it shouldn't. Given that
4130 // saved_mark_word() is conditional on whether the GC time stamp
4131 // on the region is current or not, by incrementing the GC time
4132 // stamp here we invalidate all the GC time stamps on all the
4133 // regions and saved_mark_word() will simply return top() for
4134 // all the regions. This is a nicer way of ensuring this rather
4135 // than iterating over the regions and fixing them. In fact, the
4136 // GC time stamp increment here also ensures that
4137 // saved_mark_word() will return top() between pauses, i.e.,
4138 // during concurrent refinement. So we don't need the
4139 // is_gc_active() check to decided which top to use when
4140 // scanning cards (see CR 7039627).
4141 increment_gc_time_stamp();
4142
4143 verify_after_gc();
4144
4145 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4146 ref_processor_stw()->verify_no_references_recorded();
4147
4148 // CM reference discovery will be re-enabled if necessary.
4149 }
4150
4151 // We should do this after we potentially expand the heap so
4152 // that all the COMMIT events are generated before the end GC
4153 // event, and after we retire the GC alloc regions so that all
4154 // RETIRE events are generated before the end GC event.
4155 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4156
4157 if (mark_in_progress()) {
4158 concurrent_mark()->update_g1_committed();
4159 }
4160
4161 #ifdef TRACESPINNING
4162 ParallelTaskTerminator::print_termination_counts();
4163 #endif
4164
4165 gc_epilogue(false);
4166 }
4167
4168 // Print the remainder of the GC log output.
4169 log_gc_footer(os::elapsedTime() - pause_start_sec);
4170
4171 // It is not yet to safe to tell the concurrent mark to
4172 // start as we have some optional output below. We don't want the
4173 // output from the concurrent mark thread interfering with this
4174 // logging output either.
4175
4176 _hrs.verify_optional();
4177 verify_region_sets_optional();
4178
4179 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4180 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4181
4182 print_heap_after_gc();
4183 trace_heap_after_gc(_gc_tracer_stw);
4184
4185 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4186 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4187 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4188 // before any GC notifications are raised.
4189 g1mm()->update_sizes();
4190
4191 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4192 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4193 _gc_timer_stw->register_gc_end(os::elapsed_counter());
4194 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4195 }
4196
4197 if (G1SummarizeRSetStats &&
4198 (G1SummarizeRSetStatsPeriod > 0) &&
4199 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
4200 g1_rem_set()->print_summary_info();
4201 }
4202 // It should now be safe to tell the concurrent mark thread to start
4203 // without its logging output interfering with the logging output
4204 // that came from the pause.
4205
4206 if (should_start_conc_mark) {
4207 // CAUTION: after the doConcurrentMark() call below,
4208 // the concurrent marking thread(s) could be running
4209 // concurrently with us. Make sure that anything after
4210 // this point does not assume that we are the only GC thread
4211 // running. Note: of course, the actual marking work will
4212 // not start until the safepoint itself is released in
4213 // ConcurrentGCThread::safepoint_desynchronize().
4214 doConcurrentMark();
4215 }
4216
4217 return true;
4218 }
4219
4220 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4221 {
4222 size_t gclab_word_size;
4223 switch (purpose) {
4224 case GCAllocForSurvived:
4225 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4226 break;
4227 case GCAllocForTenured:
4228 gclab_word_size = _old_plab_stats.desired_plab_sz();
4229 break;
4230 default:
4231 assert(false, "unknown GCAllocPurpose");
4232 gclab_word_size = _old_plab_stats.desired_plab_sz();
4233 break;
4234 }
4235
4236 // Prevent humongous PLAB sizes for two reasons:
4237 // * PLABs are allocated using a similar paths as oops, but should
4238 // never be in a humongous region
4239 // * Allowing humongous PLABs needlessly churns the region free lists
4240 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4241 }
4242
4243 void G1CollectedHeap::init_mutator_alloc_region() {
4244 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4245 _mutator_alloc_region.init();
4246 }
4247
4248 void G1CollectedHeap::release_mutator_alloc_region() {
4249 _mutator_alloc_region.release();
4250 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4251 }
4252
4253 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4254 assert_at_safepoint(true /* should_be_vm_thread */);
4255
4256 _survivor_gc_alloc_region.init();
4257 _old_gc_alloc_region.init();
4258 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4259 _retained_old_gc_alloc_region = NULL;
4260
4261 // We will discard the current GC alloc region if:
4262 // a) it's in the collection set (it can happen!),
4263 // b) it's already full (no point in using it),
4264 // c) it's empty (this means that it was emptied during
4265 // a cleanup and it should be on the free list now), or
4266 // d) it's humongous (this means that it was emptied
4267 // during a cleanup and was added to the free list, but
4268 // has been subsequently used to allocate a humongous
4269 // object that may be less than the region size).
4270 if (retained_region != NULL &&
4271 !retained_region->in_collection_set() &&
4272 !(retained_region->top() == retained_region->end()) &&
4273 !retained_region->is_empty() &&
4274 !retained_region->isHumongous()) {
4275 retained_region->set_saved_mark();
4276 // The retained region was added to the old region set when it was
4277 // retired. We have to remove it now, since we don't allow regions
4278 // we allocate to in the region sets. We'll re-add it later, when
4279 // it's retired again.
4280 _old_set.remove(retained_region);
4281 bool during_im = g1_policy()->during_initial_mark_pause();
4282 retained_region->note_start_of_copying(during_im);
4283 _old_gc_alloc_region.set(retained_region);
4284 _hr_printer.reuse(retained_region);
4285 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4286 }
4287 }
4288
4289 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4290 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4291 _old_gc_alloc_region.count());
4292 _survivor_gc_alloc_region.release();
4293 // If we have an old GC alloc region to release, we'll save it in
4294 // _retained_old_gc_alloc_region. If we don't
4295 // _retained_old_gc_alloc_region will become NULL. This is what we
4296 // want either way so no reason to check explicitly for either
4297 // condition.
4298 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4299
4300 if (ResizePLAB) {
4301 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4302 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4303 }
4304 }
4305
4306 void G1CollectedHeap::abandon_gc_alloc_regions() {
4307 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4308 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4309 _retained_old_gc_alloc_region = NULL;
4310 }
4311
4312 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4313 _drain_in_progress = false;
4314 set_evac_failure_closure(cl);
4315 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4316 }
4317
4318 void G1CollectedHeap::finalize_for_evac_failure() {
4319 assert(_evac_failure_scan_stack != NULL &&
4320 _evac_failure_scan_stack->length() == 0,
4321 "Postcondition");
4322 assert(!_drain_in_progress, "Postcondition");
4323 delete _evac_failure_scan_stack;
4324 _evac_failure_scan_stack = NULL;
4325 }
4326
4327 void G1CollectedHeap::remove_self_forwarding_pointers() {
4328 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4329
4330 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4331
4332 if (G1CollectedHeap::use_parallel_gc_threads()) {
4333 set_par_threads();
4334 workers()->run_task(&rsfp_task);
4335 set_par_threads(0);
4336 } else {
4337 rsfp_task.work(0);
4338 }
4339
4340 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4341
4342 // Reset the claim values in the regions in the collection set.
4343 reset_cset_heap_region_claim_values();
4344
4345 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4346
4347 // Now restore saved marks, if any.
4348 assert(_objs_with_preserved_marks.size() ==
4349 _preserved_marks_of_objs.size(), "Both or none.");
4350 while (!_objs_with_preserved_marks.is_empty()) {
4351 oop obj = _objs_with_preserved_marks.pop();
4352 markOop m = _preserved_marks_of_objs.pop();
4353 obj->set_mark(m);
4354 }
4355 _objs_with_preserved_marks.clear(true);
4356 _preserved_marks_of_objs.clear(true);
4357 }
4358
4359 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4360 _evac_failure_scan_stack->push(obj);
4361 }
4362
4363 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4364 assert(_evac_failure_scan_stack != NULL, "precondition");
4365
4366 while (_evac_failure_scan_stack->length() > 0) {
4367 oop obj = _evac_failure_scan_stack->pop();
4368 _evac_failure_closure->set_region(heap_region_containing(obj));
4369 obj->oop_iterate_backwards(_evac_failure_closure);
4370 }
4371 }
4372
4373 oop
4374 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4375 oop old) {
4376 assert(obj_in_cs(old),
4377 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4378 (HeapWord*) old));
4379 markOop m = old->mark();
4380 oop forward_ptr = old->forward_to_atomic(old);
4381 if (forward_ptr == NULL) {
4382 // Forward-to-self succeeded.
4383 assert(_par_scan_state != NULL, "par scan state");
4384 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4385 uint queue_num = _par_scan_state->queue_num();
4386
4387 _evacuation_failed = true;
4388 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4389 if (_evac_failure_closure != cl) {
4390 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4391 assert(!_drain_in_progress,
4392 "Should only be true while someone holds the lock.");
4393 // Set the global evac-failure closure to the current thread's.
4394 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4395 set_evac_failure_closure(cl);
4396 // Now do the common part.
4397 handle_evacuation_failure_common(old, m);
4398 // Reset to NULL.
4399 set_evac_failure_closure(NULL);
4400 } else {
4401 // The lock is already held, and this is recursive.
4402 assert(_drain_in_progress, "This should only be the recursive case.");
4403 handle_evacuation_failure_common(old, m);
4404 }
4405 return old;
4406 } else {
4407 // Forward-to-self failed. Either someone else managed to allocate
4408 // space for this object (old != forward_ptr) or they beat us in
4409 // self-forwarding it (old == forward_ptr).
4410 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4411 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4412 "should not be in the CSet",
4413 (HeapWord*) old, (HeapWord*) forward_ptr));
4414 return forward_ptr;
4415 }
4416 }
4417
4418 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4419 preserve_mark_if_necessary(old, m);
4420
4421 HeapRegion* r = heap_region_containing(old);
4422 if (!r->evacuation_failed()) {
4423 r->set_evacuation_failed(true);
4424 _hr_printer.evac_failure(r);
4425 }
4426
4427 push_on_evac_failure_scan_stack(old);
4428
4429 if (!_drain_in_progress) {
4430 // prevent recursion in copy_to_survivor_space()
4431 _drain_in_progress = true;
4432 drain_evac_failure_scan_stack();
4433 _drain_in_progress = false;
4434 }
4435 }
4436
4437 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4438 assert(evacuation_failed(), "Oversaving!");
4439 // We want to call the "for_promotion_failure" version only in the
4440 // case of a promotion failure.
4441 if (m->must_be_preserved_for_promotion_failure(obj)) {
4442 _objs_with_preserved_marks.push(obj);
4443 _preserved_marks_of_objs.push(m);
4444 }
4445 }
4446
4447 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4448 size_t word_size) {
4449 if (purpose == GCAllocForSurvived) {
4450 HeapWord* result = survivor_attempt_allocation(word_size);
4451 if (result != NULL) {
4452 return result;
4453 } else {
4454 // Let's try to allocate in the old gen in case we can fit the
4455 // object there.
4456 return old_attempt_allocation(word_size);
4457 }
4458 } else {
4459 assert(purpose == GCAllocForTenured, "sanity");
4460 HeapWord* result = old_attempt_allocation(word_size);
4461 if (result != NULL) {
4462 return result;
4463 } else {
4464 // Let's try to allocate in the survivors in case we can fit the
4465 // object there.
4466 return survivor_attempt_allocation(word_size);
4467 }
4468 }
4469
4470 ShouldNotReachHere();
4471 // Trying to keep some compilers happy.
4472 return NULL;
4473 }
4474
4475 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4476 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4477
4478 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4479 : _g1h(g1h),
4480 _refs(g1h->task_queue(queue_num)),
4481 _dcq(&g1h->dirty_card_queue_set()),
4482 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4483 _g1_rem(g1h->g1_rem_set()),
4484 _hash_seed(17), _queue_num(queue_num),
4485 _term_attempts(0),
4486 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4487 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4488 _age_table(false),
4489 _strong_roots_time(0), _term_time(0),
4490 _alloc_buffer_waste(0), _undo_waste(0) {
4491 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4492 // we "sacrifice" entry 0 to keep track of surviving bytes for
4493 // non-young regions (where the age is -1)
4494 // We also add a few elements at the beginning and at the end in
4495 // an attempt to eliminate cache contention
4496 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4497 uint array_length = PADDING_ELEM_NUM +
4498 real_length +
4499 PADDING_ELEM_NUM;
4500 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4501 if (_surviving_young_words_base == NULL)
4502 vm_exit_out_of_memory(array_length * sizeof(size_t),
4503 "Not enough space for young surv histo.");
4504 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4505 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4506
4507 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4508 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4509
4510 _start = os::elapsedTime();
4511 }
4512
4513 void
4514 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4515 {
4516 st->print_raw_cr("GC Termination Stats");
4517 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4518 " ------waste (KiB)------");
4519 st->print_raw_cr("thr ms ms % ms % attempts"
4520 " total alloc undo");
4521 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4522 " ------- ------- -------");
4523 }
4524
4525 void
4526 G1ParScanThreadState::print_termination_stats(int i,
4527 outputStream* const st) const
4528 {
4529 const double elapsed_ms = elapsed_time() * 1000.0;
4530 const double s_roots_ms = strong_roots_time() * 1000.0;
4531 const double term_ms = term_time() * 1000.0;
4532 st->print_cr("%3d %9.2f %9.2f %6.2f "
4533 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4534 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4535 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4536 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4537 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4538 alloc_buffer_waste() * HeapWordSize / K,
4539 undo_waste() * HeapWordSize / K);
4540 }
4541
4542 #ifdef ASSERT
4543 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4544 assert(ref != NULL, "invariant");
4545 assert(UseCompressedOops, "sanity");
4546 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4547 oop p = oopDesc::load_decode_heap_oop(ref);
4548 assert(_g1h->is_in_g1_reserved(p),
4549 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4550 return true;
4551 }
4552
4553 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4554 assert(ref != NULL, "invariant");
4555 if (has_partial_array_mask(ref)) {
4556 // Must be in the collection set--it's already been copied.
4557 oop p = clear_partial_array_mask(ref);
4558 assert(_g1h->obj_in_cs(p),
4559 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4560 } else {
4561 oop p = oopDesc::load_decode_heap_oop(ref);
4562 assert(_g1h->is_in_g1_reserved(p),
4563 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4564 }
4565 return true;
4566 }
4567
4568 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4569 if (ref.is_narrow()) {
4570 return verify_ref((narrowOop*) ref);
4571 } else {
4572 return verify_ref((oop*) ref);
4573 }
4574 }
4575 #endif // ASSERT
4576
4577 void G1ParScanThreadState::trim_queue() {
4578 assert(_evac_cl != NULL, "not set");
4579 assert(_evac_failure_cl != NULL, "not set");
4580 assert(_partial_scan_cl != NULL, "not set");
4581
4582 StarTask ref;
4583 do {
4584 // Drain the overflow stack first, so other threads can steal.
4585 while (refs()->pop_overflow(ref)) {
4586 deal_with_reference(ref);
4587 }
4588
4589 while (refs()->pop_local(ref)) {
4590 deal_with_reference(ref);
4591 }
4592 } while (!refs()->is_empty());
4593 }
4594
4595 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4596 G1ParScanThreadState* par_scan_state) :
4597 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4598 _par_scan_state(par_scan_state),
4599 _worker_id(par_scan_state->queue_num()),
4600 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4601 _mark_in_progress(_g1->mark_in_progress()) { }
4602
4603 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4604 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4605 #ifdef ASSERT
4606 HeapRegion* hr = _g1->heap_region_containing(obj);
4607 assert(hr != NULL, "sanity");
4608 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4609 #endif // ASSERT
4610
4611 // We know that the object is not moving so it's safe to read its size.
4612 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4613 }
4614
4615 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4616 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4617 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4618 #ifdef ASSERT
4619 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4620 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4621 assert(from_obj != to_obj, "should not be self-forwarded");
4622
4623 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4624 assert(from_hr != NULL, "sanity");
4625 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4626
4627 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4628 assert(to_hr != NULL, "sanity");
4629 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4630 #endif // ASSERT
4631
4632 // The object might be in the process of being copied by another
4633 // worker so we cannot trust that its to-space image is
4634 // well-formed. So we have to read its size from its from-space
4635 // image which we know should not be changing.
4636 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4637 }
4638
4639 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4640 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4641 ::copy_to_survivor_space(oop old) {
4642 size_t word_sz = old->size();
4643 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4644 // +1 to make the -1 indexes valid...
4645 int young_index = from_region->young_index_in_cset()+1;
4646 assert( (from_region->is_young() && young_index > 0) ||
4647 (!from_region->is_young() && young_index == 0), "invariant" );
4648 G1CollectorPolicy* g1p = _g1->g1_policy();
4649 markOop m = old->mark();
4650 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4651 : m->age();
4652 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4653 word_sz);
4654 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4655 #ifndef PRODUCT
4656 // Should this evacuation fail?
4657 if (_g1->evacuation_should_fail()) {
4658 if (obj_ptr != NULL) {
4659 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4660 obj_ptr = NULL;
4661 }
4662 }
4663 #endif // !PRODUCT
4664
4665 if (obj_ptr == NULL) {
4666 // This will either forward-to-self, or detect that someone else has
4667 // installed a forwarding pointer.
4668 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4669 }
4670
4671 oop obj = oop(obj_ptr);
4672
4673 // We're going to allocate linearly, so might as well prefetch ahead.
4674 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4675
4676 oop forward_ptr = old->forward_to_atomic(obj);
4677 if (forward_ptr == NULL) {
4678 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4679 if (g1p->track_object_age(alloc_purpose)) {
4680 // We could simply do obj->incr_age(). However, this causes a
4681 // performance issue. obj->incr_age() will first check whether
4682 // the object has a displaced mark by checking its mark word;
4683 // getting the mark word from the new location of the object
4684 // stalls. So, given that we already have the mark word and we
4685 // are about to install it anyway, it's better to increase the
4686 // age on the mark word, when the object does not have a
4687 // displaced mark word. We're not expecting many objects to have
4688 // a displaced marked word, so that case is not optimized
4689 // further (it could be...) and we simply call obj->incr_age().
4690
4691 if (m->has_displaced_mark_helper()) {
4692 // in this case, we have to install the mark word first,
4693 // otherwise obj looks to be forwarded (the old mark word,
4694 // which contains the forward pointer, was copied)
4695 obj->set_mark(m);
4696 obj->incr_age();
4697 } else {
4698 m = m->incr_age();
4699 obj->set_mark(m);
4700 }
4701 _par_scan_state->age_table()->add(obj, word_sz);
4702 } else {
4703 obj->set_mark(m);
4704 }
4705
4706 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4707 surv_young_words[young_index] += word_sz;
4708
4709 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4710 // We keep track of the next start index in the length field of
4711 // the to-space object. The actual length can be found in the
4712 // length field of the from-space object.
4713 arrayOop(obj)->set_length(0);
4714 oop* old_p = set_partial_array_mask(old);
4715 _par_scan_state->push_on_queue(old_p);
4716 } else {
4717 // No point in using the slower heap_region_containing() method,
4718 // given that we know obj is in the heap.
4719 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4720 obj->oop_iterate_backwards(&_scanner);
4721 }
4722 } else {
4723 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4724 obj = forward_ptr;
4725 }
4726 return obj;
4727 }
4728
4729 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4730 template <class T>
4731 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4732 ::do_oop_work(T* p) {
4733 oop obj = oopDesc::load_decode_heap_oop(p);
4734 assert(barrier != G1BarrierRS || obj != NULL,
4735 "Precondition: G1BarrierRS implies obj is non-NULL");
4736
4737 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4738
4739 // here the null check is implicit in the cset_fast_test() test
4740 if (_g1->in_cset_fast_test(obj)) {
4741 oop forwardee;
4742 if (obj->is_forwarded()) {
4743 forwardee = obj->forwardee();
4744 } else {
4745 forwardee = copy_to_survivor_space(obj);
4746 }
4747 assert(forwardee != NULL, "forwardee should not be NULL");
4748 oopDesc::encode_store_heap_oop(p, forwardee);
4749 if (do_mark_object && forwardee != obj) {
4750 // If the object is self-forwarded we don't need to explicitly
4751 // mark it, the evacuation failure protocol will do so.
4752 mark_forwarded_object(obj, forwardee);
4753 }
4754
4755 // When scanning the RS, we only care about objs in CS.
4756 if (barrier == G1BarrierRS) {
4757 _par_scan_state->update_rs(_from, p, _worker_id);
4758 }
4759 } else {
4760 // The object is not in collection set. If we're a root scanning
4761 // closure during an initial mark pause (i.e. do_mark_object will
4762 // be true) then attempt to mark the object.
4763 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4764 mark_object(obj);
4765 }
4766 }
4767
4768 if (barrier == G1BarrierEvac && obj != NULL) {
4769 _par_scan_state->update_rs(_from, p, _worker_id);
4770 }
4771
4772 if (do_gen_barrier && obj != NULL) {
4773 par_do_barrier(p);
4774 }
4775 }
4776
4777 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4778 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4779
4780 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4781 assert(has_partial_array_mask(p), "invariant");
4782 oop from_obj = clear_partial_array_mask(p);
4783
4784 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4785 assert(from_obj->is_objArray(), "must be obj array");
4786 objArrayOop from_obj_array = objArrayOop(from_obj);
4787 // The from-space object contains the real length.
4788 int length = from_obj_array->length();
4789
4790 assert(from_obj->is_forwarded(), "must be forwarded");
4791 oop to_obj = from_obj->forwardee();
4792 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4793 objArrayOop to_obj_array = objArrayOop(to_obj);
4794 // We keep track of the next start index in the length field of the
4795 // to-space object.
4796 int next_index = to_obj_array->length();
4797 assert(0 <= next_index && next_index < length,
4798 err_msg("invariant, next index: %d, length: %d", next_index, length));
4799
4800 int start = next_index;
4801 int end = length;
4802 int remainder = end - start;
4803 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4804 if (remainder > 2 * ParGCArrayScanChunk) {
4805 end = start + ParGCArrayScanChunk;
4806 to_obj_array->set_length(end);
4807 // Push the remainder before we process the range in case another
4808 // worker has run out of things to do and can steal it.
4809 oop* from_obj_p = set_partial_array_mask(from_obj);
4810 _par_scan_state->push_on_queue(from_obj_p);
4811 } else {
4812 assert(length == end, "sanity");
4813 // We'll process the final range for this object. Restore the length
4814 // so that the heap remains parsable in case of evacuation failure.
4815 to_obj_array->set_length(end);
4816 }
4817 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4818 // Process indexes [start,end). It will also process the header
4819 // along with the first chunk (i.e., the chunk with start == 0).
4820 // Note that at this point the length field of to_obj_array is not
4821 // correct given that we are using it to keep track of the next
4822 // start index. oop_iterate_range() (thankfully!) ignores the length
4823 // field and only relies on the start / end parameters. It does
4824 // however return the size of the object which will be incorrect. So
4825 // we have to ignore it even if we wanted to use it.
4826 to_obj_array->oop_iterate_range(&_scanner, start, end);
4827 }
4828
4829 class G1ParEvacuateFollowersClosure : public VoidClosure {
4830 protected:
4831 G1CollectedHeap* _g1h;
4832 G1ParScanThreadState* _par_scan_state;
4833 RefToScanQueueSet* _queues;
4834 ParallelTaskTerminator* _terminator;
4835
4836 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4837 RefToScanQueueSet* queues() { return _queues; }
4838 ParallelTaskTerminator* terminator() { return _terminator; }
4839
4840 public:
4841 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4842 G1ParScanThreadState* par_scan_state,
4843 RefToScanQueueSet* queues,
4844 ParallelTaskTerminator* terminator)
4845 : _g1h(g1h), _par_scan_state(par_scan_state),
4846 _queues(queues), _terminator(terminator) {}
4847
4848 void do_void();
4849
4850 private:
4851 inline bool offer_termination();
4852 };
4853
4854 bool G1ParEvacuateFollowersClosure::offer_termination() {
4855 G1ParScanThreadState* const pss = par_scan_state();
4856 pss->start_term_time();
4857 const bool res = terminator()->offer_termination();
4858 pss->end_term_time();
4859 return res;
4860 }
4861
4862 void G1ParEvacuateFollowersClosure::do_void() {
4863 StarTask stolen_task;
4864 G1ParScanThreadState* const pss = par_scan_state();
4865 pss->trim_queue();
4866
4867 do {
4868 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4869 assert(pss->verify_task(stolen_task), "sanity");
4870 if (stolen_task.is_narrow()) {
4871 pss->deal_with_reference((narrowOop*) stolen_task);
4872 } else {
4873 pss->deal_with_reference((oop*) stolen_task);
4874 }
4875
4876 // We've just processed a reference and we might have made
4877 // available new entries on the queues. So we have to make sure
4878 // we drain the queues as necessary.
4879 pss->trim_queue();
4880 }
4881 } while (!offer_termination());
4882
4883 pss->retire_alloc_buffers();
4884 }
4885
4886 class G1ParTask : public AbstractGangTask {
4887 protected:
4888 G1CollectedHeap* _g1h;
4889 RefToScanQueueSet *_queues;
4890 ParallelTaskTerminator _terminator;
4891 uint _n_workers;
4892
4893 Mutex _stats_lock;
4894 Mutex* stats_lock() { return &_stats_lock; }
4895
4896 size_t getNCards() {
4897 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4898 / G1BlockOffsetSharedArray::N_bytes;
4899 }
4900
4901 public:
4902 G1ParTask(G1CollectedHeap* g1h,
4903 RefToScanQueueSet *task_queues)
4904 : AbstractGangTask("G1 collection"),
4905 _g1h(g1h),
4906 _queues(task_queues),
4907 _terminator(0, _queues),
4908 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4909 {}
4910
4911 RefToScanQueueSet* queues() { return _queues; }
4912
4913 RefToScanQueue *work_queue(int i) {
4914 return queues()->queue(i);
4915 }
4916
4917 ParallelTaskTerminator* terminator() { return &_terminator; }
4918
4919 virtual void set_for_termination(int active_workers) {
4920 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4921 // in the young space (_par_seq_tasks) in the G1 heap
4922 // for SequentialSubTasksDone.
4923 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4924 // both of which need setting by set_n_termination().
4925 _g1h->SharedHeap::set_n_termination(active_workers);
4926 _g1h->set_n_termination(active_workers);
4927 terminator()->reset_for_reuse(active_workers);
4928 _n_workers = active_workers;
4929 }
4930
4931 void work(uint worker_id) {
4932 if (worker_id >= _n_workers) return; // no work needed this round
4933
4934 double start_time_ms = os::elapsedTime() * 1000.0;
4935 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4936
4937 {
4938 ResourceMark rm;
4939 HandleMark hm;
4940
4941 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4942
4943 G1ParScanThreadState pss(_g1h, worker_id);
4944 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4945 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4946 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4947
4948 pss.set_evac_closure(&scan_evac_cl);
4949 pss.set_evac_failure_closure(&evac_failure_cl);
4950 pss.set_partial_scan_closure(&partial_scan_cl);
4951
4952 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4953 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp);
4954
4955 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4956 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp);
4957
4958 OopClosure* scan_root_cl = &only_scan_root_cl;
4959 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl;
4960
4961 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4962 // We also need to mark copied objects.
4963 scan_root_cl = &scan_mark_root_cl;
4964 scan_perm_cl = &scan_mark_perm_cl;
4965 }
4966
4967 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4968
4969 pss.start_strong_roots();
4970 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4971 SharedHeap::SO_AllClasses,
4972 scan_root_cl,
4973 &push_heap_rs_cl,
4974 scan_perm_cl,
4975 worker_id);
4976 pss.end_strong_roots();
4977
4978 {
4979 double start = os::elapsedTime();
4980 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4981 evac.do_void();
4982 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4983 double term_ms = pss.term_time()*1000.0;
4984 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4985 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4986 }
4987 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4988 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4989
4990 if (ParallelGCVerbose) {
4991 MutexLocker x(stats_lock());
4992 pss.print_termination_stats(worker_id);
4993 }
4994
4995 assert(pss.refs()->is_empty(), "should be empty");
4996
4997 // Close the inner scope so that the ResourceMark and HandleMark
4998 // destructors are executed here and are included as part of the
4999 // "GC Worker Time".
5000 }
5001
5002 double end_time_ms = os::elapsedTime() * 1000.0;
5003 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5004 }
5005 };
5006
5007 // *** Common G1 Evacuation Stuff
5008
5009 // Closures that support the filtering of CodeBlobs scanned during
5010 // external root scanning.
5011
5012 // Closure applied to reference fields in code blobs (specifically nmethods)
5013 // to determine whether an nmethod contains references that point into
5014 // the collection set. Used as a predicate when walking code roots so
5015 // that only nmethods that point into the collection set are added to the
5016 // 'marked' list.
5017
5018 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
5019
5020 class G1PointsIntoCSOopClosure : public OopClosure {
5021 G1CollectedHeap* _g1;
5022 bool _points_into_cs;
5023 public:
5024 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
5025 _g1(g1), _points_into_cs(false) { }
5026
5027 bool points_into_cs() const { return _points_into_cs; }
5028
5029 template <class T>
5030 void do_oop_nv(T* p) {
5031 if (!_points_into_cs) {
5032 T heap_oop = oopDesc::load_heap_oop(p);
5033 if (!oopDesc::is_null(heap_oop) &&
5034 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
5035 _points_into_cs = true;
5036 }
5037 }
5038 }
5039
5040 virtual void do_oop(oop* p) { do_oop_nv(p); }
5041 virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
5042 };
5043
5044 G1CollectedHeap* _g1;
5045
5046 public:
5047 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
5048 CodeBlobToOopClosure(cl, true), _g1(g1) { }
5049
5050 virtual void do_code_blob(CodeBlob* cb) {
5051 nmethod* nm = cb->as_nmethod_or_null();
5052 if (nm != NULL && !(nm->test_oops_do_mark())) {
5053 G1PointsIntoCSOopClosure predicate_cl(_g1);
5054 nm->oops_do(&predicate_cl);
5055
5056 if (predicate_cl.points_into_cs()) {
5057 // At least one of the reference fields or the oop relocations
5058 // in the nmethod points into the collection set. We have to
5059 // 'mark' this nmethod.
5060 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
5061 // or MarkingCodeBlobClosure::do_code_blob() change.
5062 if (!nm->test_set_oops_do_mark()) {
5063 do_newly_marked_nmethod(nm);
5064 }
5065 }
5066 }
5067 }
5068 };
5069
5070 // This method is run in a GC worker.
5071
5072 void
5073 G1CollectedHeap::
5074 g1_process_strong_roots(bool collecting_perm_gen,
5075 ScanningOption so,
5076 OopClosure* scan_non_heap_roots,
5077 OopsInHeapRegionClosure* scan_rs,
5078 OopsInGenClosure* scan_perm,
5079 int worker_i) {
5080
5081 // First scan the strong roots, including the perm gen.
5082 double ext_roots_start = os::elapsedTime();
5083 double closure_app_time_sec = 0.0;
5084
5085 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5086 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
5087 buf_scan_perm.set_generation(perm_gen());
5088
5089 // Walk the code cache w/o buffering, because StarTask cannot handle
5090 // unaligned oop locations.
5091 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5092
5093 process_strong_roots(false, // no scoping; this is parallel code
5094 collecting_perm_gen, so,
5095 &buf_scan_non_heap_roots,
5096 &eager_scan_code_roots,
5097 &buf_scan_perm);
5098
5099 // Now the CM ref_processor roots.
5100 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5101 // We need to treat the discovered reference lists of the
5102 // concurrent mark ref processor as roots and keep entries
5103 // (which are added by the marking threads) on them live
5104 // until they can be processed at the end of marking.
5105 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5106 }
5107
5108 // Finish up any enqueued closure apps (attributed as object copy time).
5109 buf_scan_non_heap_roots.done();
5110 buf_scan_perm.done();
5111
5112 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
5113 buf_scan_non_heap_roots.closure_app_seconds();
5114 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5115
5116 double ext_root_time_ms =
5117 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5118
5119 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5120
5121 // During conc marking we have to filter the per-thread SATB buffers
5122 // to make sure we remove any oops into the CSet (which will show up
5123 // as implicitly live).
5124 double satb_filtering_ms = 0.0;
5125 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5126 if (mark_in_progress()) {
5127 double satb_filter_start = os::elapsedTime();
5128
5129 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5130
5131 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5132 }
5133 }
5134 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5135
5136 // Now scan the complement of the collection set.
5137 if (scan_rs != NULL) {
5138 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5139 }
5140
5141 _process_strong_tasks->all_tasks_completed();
5142 }
5143
5144 void
5145 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
5146 OopClosure* non_root_closure) {
5147 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5148 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
5149 }
5150
5151 // Weak Reference Processing support
5152
5153 // An always "is_alive" closure that is used to preserve referents.
5154 // If the object is non-null then it's alive. Used in the preservation
5155 // of referent objects that are pointed to by reference objects
5156 // discovered by the CM ref processor.
5157 class G1AlwaysAliveClosure: public BoolObjectClosure {
5158 G1CollectedHeap* _g1;
5159 public:
5160 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5161 void do_object(oop p) { assert(false, "Do not call."); }
5162 bool do_object_b(oop p) {
5163 if (p != NULL) {
5164 return true;
5165 }
5166 return false;
5167 }
5168 };
5169
5170 bool G1STWIsAliveClosure::do_object_b(oop p) {
5171 // An object is reachable if it is outside the collection set,
5172 // or is inside and copied.
5173 return !_g1->obj_in_cs(p) || p->is_forwarded();
5174 }
5175
5176 // Non Copying Keep Alive closure
5177 class G1KeepAliveClosure: public OopClosure {
5178 G1CollectedHeap* _g1;
5179 public:
5180 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5181 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5182 void do_oop( oop* p) {
5183 oop obj = *p;
5184
5185 if (_g1->obj_in_cs(obj)) {
5186 assert( obj->is_forwarded(), "invariant" );
5187 *p = obj->forwardee();
5188 }
5189 }
5190 };
5191
5192 // Copying Keep Alive closure - can be called from both
5193 // serial and parallel code as long as different worker
5194 // threads utilize different G1ParScanThreadState instances
5195 // and different queues.
5196
5197 class G1CopyingKeepAliveClosure: public OopClosure {
5198 G1CollectedHeap* _g1h;
5199 OopClosure* _copy_non_heap_obj_cl;
5200 OopsInHeapRegionClosure* _copy_perm_obj_cl;
5201 G1ParScanThreadState* _par_scan_state;
5202
5203 public:
5204 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5205 OopClosure* non_heap_obj_cl,
5206 OopsInHeapRegionClosure* perm_obj_cl,
5207 G1ParScanThreadState* pss):
5208 _g1h(g1h),
5209 _copy_non_heap_obj_cl(non_heap_obj_cl),
5210 _copy_perm_obj_cl(perm_obj_cl),
5211 _par_scan_state(pss)
5212 {}
5213
5214 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5215 virtual void do_oop( oop* p) { do_oop_work(p); }
5216
5217 template <class T> void do_oop_work(T* p) {
5218 oop obj = oopDesc::load_decode_heap_oop(p);
5219
5220 if (_g1h->obj_in_cs(obj)) {
5221 // If the referent object has been forwarded (either copied
5222 // to a new location or to itself in the event of an
5223 // evacuation failure) then we need to update the reference
5224 // field and, if both reference and referent are in the G1
5225 // heap, update the RSet for the referent.
5226 //
5227 // If the referent has not been forwarded then we have to keep
5228 // it alive by policy. Therefore we have copy the referent.
5229 //
5230 // If the reference field is in the G1 heap then we can push
5231 // on the PSS queue. When the queue is drained (after each
5232 // phase of reference processing) the object and it's followers
5233 // will be copied, the reference field set to point to the
5234 // new location, and the RSet updated. Otherwise we need to
5235 // use the the non-heap or perm closures directly to copy
5236 // the referent object and update the pointer, while avoiding
5237 // updating the RSet.
5238
5239 if (_g1h->is_in_g1_reserved(p)) {
5240 _par_scan_state->push_on_queue(p);
5241 } else {
5242 // The reference field is not in the G1 heap.
5243 if (_g1h->perm_gen()->is_in(p)) {
5244 _copy_perm_obj_cl->do_oop(p);
5245 } else {
5246 _copy_non_heap_obj_cl->do_oop(p);
5247 }
5248 }
5249 }
5250 }
5251 };
5252
5253 // Serial drain queue closure. Called as the 'complete_gc'
5254 // closure for each discovered list in some of the
5255 // reference processing phases.
5256
5257 class G1STWDrainQueueClosure: public VoidClosure {
5258 protected:
5259 G1CollectedHeap* _g1h;
5260 G1ParScanThreadState* _par_scan_state;
5261
5262 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5263
5264 public:
5265 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5266 _g1h(g1h),
5267 _par_scan_state(pss)
5268 { }
5269
5270 void do_void() {
5271 G1ParScanThreadState* const pss = par_scan_state();
5272 pss->trim_queue();
5273 }
5274 };
5275
5276 // Parallel Reference Processing closures
5277
5278 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5279 // processing during G1 evacuation pauses.
5280
5281 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5282 private:
5283 G1CollectedHeap* _g1h;
5284 RefToScanQueueSet* _queues;
5285 FlexibleWorkGang* _workers;
5286 int _active_workers;
5287
5288 public:
5289 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5290 FlexibleWorkGang* workers,
5291 RefToScanQueueSet *task_queues,
5292 int n_workers) :
5293 _g1h(g1h),
5294 _queues(task_queues),
5295 _workers(workers),
5296 _active_workers(n_workers)
5297 {
5298 assert(n_workers > 0, "shouldn't call this otherwise");
5299 }
5300
5301 // Executes the given task using concurrent marking worker threads.
5302 virtual void execute(ProcessTask& task);
5303 virtual void execute(EnqueueTask& task);
5304 };
5305
5306 // Gang task for possibly parallel reference processing
5307
5308 class G1STWRefProcTaskProxy: public AbstractGangTask {
5309 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5310 ProcessTask& _proc_task;
5311 G1CollectedHeap* _g1h;
5312 RefToScanQueueSet *_task_queues;
5313 ParallelTaskTerminator* _terminator;
5314
5315 public:
5316 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5317 G1CollectedHeap* g1h,
5318 RefToScanQueueSet *task_queues,
5319 ParallelTaskTerminator* terminator) :
5320 AbstractGangTask("Process reference objects in parallel"),
5321 _proc_task(proc_task),
5322 _g1h(g1h),
5323 _task_queues(task_queues),
5324 _terminator(terminator)
5325 {}
5326
5327 virtual void work(uint worker_id) {
5328 // The reference processing task executed by a single worker.
5329 ResourceMark rm;
5330 HandleMark hm;
5331
5332 G1STWIsAliveClosure is_alive(_g1h);
5333
5334 G1ParScanThreadState pss(_g1h, worker_id);
5335
5336 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5337 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5338 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5339
5340 pss.set_evac_closure(&scan_evac_cl);
5341 pss.set_evac_failure_closure(&evac_failure_cl);
5342 pss.set_partial_scan_closure(&partial_scan_cl);
5343
5344 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5345 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5346
5347 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5348 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5349
5350 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5351 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5352
5353 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5354 // We also need to mark copied objects.
5355 copy_non_heap_cl = ©_mark_non_heap_cl;
5356 copy_perm_cl = ©_mark_perm_cl;
5357 }
5358
5359 // Keep alive closure.
5360 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5361
5362 // Complete GC closure
5363 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5364
5365 // Call the reference processing task's work routine.
5366 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5367
5368 // Note we cannot assert that the refs array is empty here as not all
5369 // of the processing tasks (specifically phase2 - pp2_work) execute
5370 // the complete_gc closure (which ordinarily would drain the queue) so
5371 // the queue may not be empty.
5372 }
5373 };
5374
5375 // Driver routine for parallel reference processing.
5376 // Creates an instance of the ref processing gang
5377 // task and has the worker threads execute it.
5378 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5379 assert(_workers != NULL, "Need parallel worker threads.");
5380
5381 ParallelTaskTerminator terminator(_active_workers, _queues);
5382 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5383
5384 _g1h->set_par_threads(_active_workers);
5385 _workers->run_task(&proc_task_proxy);
5386 _g1h->set_par_threads(0);
5387 }
5388
5389 // Gang task for parallel reference enqueueing.
5390
5391 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5392 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5393 EnqueueTask& _enq_task;
5394
5395 public:
5396 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5397 AbstractGangTask("Enqueue reference objects in parallel"),
5398 _enq_task(enq_task)
5399 { }
5400
5401 virtual void work(uint worker_id) {
5402 _enq_task.work(worker_id);
5403 }
5404 };
5405
5406 // Driver routine for parallel reference enqueueing.
5407 // Creates an instance of the ref enqueueing gang
5408 // task and has the worker threads execute it.
5409
5410 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5411 assert(_workers != NULL, "Need parallel worker threads.");
5412
5413 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5414
5415 _g1h->set_par_threads(_active_workers);
5416 _workers->run_task(&enq_task_proxy);
5417 _g1h->set_par_threads(0);
5418 }
5419
5420 // End of weak reference support closures
5421
5422 // Abstract task used to preserve (i.e. copy) any referent objects
5423 // that are in the collection set and are pointed to by reference
5424 // objects discovered by the CM ref processor.
5425
5426 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5427 protected:
5428 G1CollectedHeap* _g1h;
5429 RefToScanQueueSet *_queues;
5430 ParallelTaskTerminator _terminator;
5431 uint _n_workers;
5432
5433 public:
5434 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5435 AbstractGangTask("ParPreserveCMReferents"),
5436 _g1h(g1h),
5437 _queues(task_queues),
5438 _terminator(workers, _queues),
5439 _n_workers(workers)
5440 { }
5441
5442 void work(uint worker_id) {
5443 ResourceMark rm;
5444 HandleMark hm;
5445
5446 G1ParScanThreadState pss(_g1h, worker_id);
5447 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5448 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5449 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5450
5451 pss.set_evac_closure(&scan_evac_cl);
5452 pss.set_evac_failure_closure(&evac_failure_cl);
5453 pss.set_partial_scan_closure(&partial_scan_cl);
5454
5455 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5456
5457
5458 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5459 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5460
5461 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5462 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5463
5464 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5465 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5466
5467 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5468 // We also need to mark copied objects.
5469 copy_non_heap_cl = ©_mark_non_heap_cl;
5470 copy_perm_cl = ©_mark_perm_cl;
5471 }
5472
5473 // Is alive closure
5474 G1AlwaysAliveClosure always_alive(_g1h);
5475
5476 // Copying keep alive closure. Applied to referent objects that need
5477 // to be copied.
5478 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5479
5480 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5481
5482 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5483 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5484
5485 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5486 // So this must be true - but assert just in case someone decides to
5487 // change the worker ids.
5488 assert(0 <= worker_id && worker_id < limit, "sanity");
5489 assert(!rp->discovery_is_atomic(), "check this code");
5490
5491 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5492 for (uint idx = worker_id; idx < limit; idx += stride) {
5493 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5494
5495 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5496 while (iter.has_next()) {
5497 // Since discovery is not atomic for the CM ref processor, we
5498 // can see some null referent objects.
5499 iter.load_ptrs(DEBUG_ONLY(true));
5500 oop ref = iter.obj();
5501
5502 // This will filter nulls.
5503 if (iter.is_referent_alive()) {
5504 iter.make_referent_alive();
5505 }
5506 iter.move_to_next();
5507 }
5508 }
5509
5510 // Drain the queue - which may cause stealing
5511 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5512 drain_queue.do_void();
5513 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5514 assert(pss.refs()->is_empty(), "should be");
5515 }
5516 };
5517
5518 // Weak Reference processing during an evacuation pause (part 1).
5519 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5520 double ref_proc_start = os::elapsedTime();
5521
5522 ReferenceProcessor* rp = _ref_processor_stw;
5523 assert(rp->discovery_enabled(), "should have been enabled");
5524
5525 // Any reference objects, in the collection set, that were 'discovered'
5526 // by the CM ref processor should have already been copied (either by
5527 // applying the external root copy closure to the discovered lists, or
5528 // by following an RSet entry).
5529 //
5530 // But some of the referents, that are in the collection set, that these
5531 // reference objects point to may not have been copied: the STW ref
5532 // processor would have seen that the reference object had already
5533 // been 'discovered' and would have skipped discovering the reference,
5534 // but would not have treated the reference object as a regular oop.
5535 // As a result the copy closure would not have been applied to the
5536 // referent object.
5537 //
5538 // We need to explicitly copy these referent objects - the references
5539 // will be processed at the end of remarking.
5540 //
5541 // We also need to do this copying before we process the reference
5542 // objects discovered by the STW ref processor in case one of these
5543 // referents points to another object which is also referenced by an
5544 // object discovered by the STW ref processor.
5545
5546 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5547 no_of_gc_workers == workers()->active_workers(),
5548 "Need to reset active GC workers");
5549
5550 set_par_threads(no_of_gc_workers);
5551 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5552 no_of_gc_workers,
5553 _task_queues);
5554
5555 if (G1CollectedHeap::use_parallel_gc_threads()) {
5556 workers()->run_task(&keep_cm_referents);
5557 } else {
5558 keep_cm_referents.work(0);
5559 }
5560
5561 set_par_threads(0);
5562
5563 // Closure to test whether a referent is alive.
5564 G1STWIsAliveClosure is_alive(this);
5565
5566 // Even when parallel reference processing is enabled, the processing
5567 // of JNI refs is serial and performed serially by the current thread
5568 // rather than by a worker. The following PSS will be used for processing
5569 // JNI refs.
5570
5571 // Use only a single queue for this PSS.
5572 G1ParScanThreadState pss(this, 0);
5573
5574 // We do not embed a reference processor in the copying/scanning
5575 // closures while we're actually processing the discovered
5576 // reference objects.
5577 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5578 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5579 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5580
5581 pss.set_evac_closure(&scan_evac_cl);
5582 pss.set_evac_failure_closure(&evac_failure_cl);
5583 pss.set_partial_scan_closure(&partial_scan_cl);
5584
5585 assert(pss.refs()->is_empty(), "pre-condition");
5586
5587 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5588 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL);
5589
5590 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5591 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL);
5592
5593 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5594 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5595
5596 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5597 // We also need to mark copied objects.
5598 copy_non_heap_cl = ©_mark_non_heap_cl;
5599 copy_perm_cl = ©_mark_perm_cl;
5600 }
5601
5602 // Keep alive closure.
5603 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5604
5605 // Serial Complete GC closure
5606 G1STWDrainQueueClosure drain_queue(this, &pss);
5607
5608 // Setup the soft refs policy...
5609 rp->setup_policy(false);
5610
5611 ReferenceProcessorStats stats;
5612 if (!rp->processing_is_mt()) {
5613 // Serial reference processing...
5614 stats = rp->process_discovered_references(&is_alive,
5615 &keep_alive,
5616 &drain_queue,
5617 NULL,
5618 _gc_timer_stw);
5619 } else {
5620 // Parallel reference processing
5621 assert(rp->num_q() == no_of_gc_workers, "sanity");
5622 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5623
5624 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5625 stats = rp->process_discovered_references(&is_alive,
5626 &keep_alive,
5627 &drain_queue,
5628 &par_task_executor,
5629 _gc_timer_stw);
5630 }
5631
5632 _gc_tracer_stw->report_gc_reference_stats(stats);
5633 // We have completed copying any necessary live referent objects
5634 // (that were not copied during the actual pause) so we can
5635 // retire any active alloc buffers
5636 pss.retire_alloc_buffers();
5637 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5638
5639 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5640 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5641 }
5642
5643 // Weak Reference processing during an evacuation pause (part 2).
5644 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5645 double ref_enq_start = os::elapsedTime();
5646
5647 ReferenceProcessor* rp = _ref_processor_stw;
5648 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5649
5650 // Now enqueue any remaining on the discovered lists on to
5651 // the pending list.
5652 if (!rp->processing_is_mt()) {
5653 // Serial reference processing...
5654 rp->enqueue_discovered_references();
5655 } else {
5656 // Parallel reference enqueueing
5657
5658 assert(no_of_gc_workers == workers()->active_workers(),
5659 "Need to reset active workers");
5660 assert(rp->num_q() == no_of_gc_workers, "sanity");
5661 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5662
5663 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5664 rp->enqueue_discovered_references(&par_task_executor);
5665 }
5666
5667 rp->verify_no_references_recorded();
5668 assert(!rp->discovery_enabled(), "should have been disabled");
5669
5670 // FIXME
5671 // CM's reference processing also cleans up the string and symbol tables.
5672 // Should we do that here also? We could, but it is a serial operation
5673 // and could significantly increase the pause time.
5674
5675 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5676 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5677 }
5678
5679 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5680 _expand_heap_after_alloc_failure = true;
5681 _evacuation_failed = false;
5682
5683 // Should G1EvacuationFailureALot be in effect for this GC?
5684 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5685
5686 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5687 concurrent_g1_refine()->set_use_cache(false);
5688 concurrent_g1_refine()->clear_hot_cache_claimed_index();
5689
5690 uint n_workers;
5691 if (G1CollectedHeap::use_parallel_gc_threads()) {
5692 n_workers =
5693 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5694 workers()->active_workers(),
5695 Threads::number_of_non_daemon_threads());
5696 assert(UseDynamicNumberOfGCThreads ||
5697 n_workers == workers()->total_workers(),
5698 "If not dynamic should be using all the workers");
5699 workers()->set_active_workers(n_workers);
5700 set_par_threads(n_workers);
5701 } else {
5702 assert(n_par_threads() == 0,
5703 "Should be the original non-parallel value");
5704 n_workers = 1;
5705 }
5706
5707 G1ParTask g1_par_task(this, _task_queues);
5708
5709 init_for_evac_failure(NULL);
5710
5711 rem_set()->prepare_for_younger_refs_iterate(true);
5712
5713 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5714 double start_par_time_sec = os::elapsedTime();
5715 double end_par_time_sec;
5716
5717 {
5718 StrongRootsScope srs(this);
5719
5720 if (G1CollectedHeap::use_parallel_gc_threads()) {
5721 // The individual threads will set their evac-failure closures.
5722 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5723 // These tasks use ShareHeap::_process_strong_tasks
5724 assert(UseDynamicNumberOfGCThreads ||
5725 workers()->active_workers() == workers()->total_workers(),
5726 "If not dynamic should be using all the workers");
5727 workers()->run_task(&g1_par_task);
5728 } else {
5729 g1_par_task.set_for_termination(n_workers);
5730 g1_par_task.work(0);
5731 }
5732 end_par_time_sec = os::elapsedTime();
5733
5734 // Closing the inner scope will execute the destructor
5735 // for the StrongRootsScope object. We record the current
5736 // elapsed time before closing the scope so that time
5737 // taken for the SRS destructor is NOT included in the
5738 // reported parallel time.
5739 }
5740
5741 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5742 g1_policy()->phase_times()->record_par_time(par_time_ms);
5743
5744 double code_root_fixup_time_ms =
5745 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5746 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5747
5748 set_par_threads(0);
5749
5750 // Process any discovered reference objects - we have
5751 // to do this _before_ we retire the GC alloc regions
5752 // as we may have to copy some 'reachable' referent
5753 // objects (and their reachable sub-graphs) that were
5754 // not copied during the pause.
5755 process_discovered_references(n_workers);
5756
5757 // Weak root processing.
5758 // Note: when JSR 292 is enabled and code blobs can contain
5759 // non-perm oops then we will need to process the code blobs
5760 // here too.
5761 {
5762 G1STWIsAliveClosure is_alive(this);
5763 G1KeepAliveClosure keep_alive(this);
5764 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5765 }
5766
5767 release_gc_alloc_regions(n_workers, evacuation_info);
5768 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5769
5770 concurrent_g1_refine()->clear_hot_cache();
5771 concurrent_g1_refine()->set_use_cache(true);
5772
5773 finalize_for_evac_failure();
5774
5775 if (evacuation_failed()) {
5776 remove_self_forwarding_pointers();
5777
5778 // Reset the G1EvacuationFailureALot counters and flags
5779 // Note: the values are reset only when an actual
5780 // evacuation failure occurs.
5781 NOT_PRODUCT(reset_evacuation_should_fail();)
5782 }
5783
5784 // Enqueue any remaining references remaining on the STW
5785 // reference processor's discovered lists. We need to do
5786 // this after the card table is cleaned (and verified) as
5787 // the act of enqueueing entries on to the pending list
5788 // will log these updates (and dirty their associated
5789 // cards). We need these updates logged to update any
5790 // RSets.
5791 enqueue_discovered_references(n_workers);
5792
5793 if (G1DeferredRSUpdate) {
5794 RedirtyLoggedCardTableEntryFastClosure redirty;
5795 dirty_card_queue_set().set_closure(&redirty);
5796 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5797
5798 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5799 dcq.merge_bufferlists(&dirty_card_queue_set());
5800 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5801 }
5802 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5803 }
5804
5805 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5806 size_t* pre_used,
5807 FreeRegionList* free_list,
5808 OldRegionSet* old_proxy_set,
5809 HumongousRegionSet* humongous_proxy_set,
5810 HRRSCleanupTask* hrrs_cleanup_task,
5811 bool par) {
5812 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5813 if (hr->isHumongous()) {
5814 assert(hr->startsHumongous(), "we should only see starts humongous");
5815 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5816 } else {
5817 _old_set.remove_with_proxy(hr, old_proxy_set);
5818 free_region(hr, pre_used, free_list, par);
5819 }
5820 } else {
5821 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5822 }
5823 }
5824
5825 void G1CollectedHeap::free_region(HeapRegion* hr,
5826 size_t* pre_used,
5827 FreeRegionList* free_list,
5828 bool par) {
5829 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5830 assert(!hr->is_empty(), "the region should not be empty");
5831 assert(free_list != NULL, "pre-condition");
5832
5833 *pre_used += hr->used();
5834 hr->hr_clear(par, true /* clear_space */);
5835 free_list->add_as_head(hr);
5836 }
5837
5838 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5839 size_t* pre_used,
5840 FreeRegionList* free_list,
5841 HumongousRegionSet* humongous_proxy_set,
5842 bool par) {
5843 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5844 assert(free_list != NULL, "pre-condition");
5845 assert(humongous_proxy_set != NULL, "pre-condition");
5846
5847 size_t hr_used = hr->used();
5848 size_t hr_capacity = hr->capacity();
5849 size_t hr_pre_used = 0;
5850 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5851 // We need to read this before we make the region non-humongous,
5852 // otherwise the information will be gone.
5853 uint last_index = hr->last_hc_index();
5854 hr->set_notHumongous();
5855 free_region(hr, &hr_pre_used, free_list, par);
5856
5857 uint i = hr->hrs_index() + 1;
5858 while (i < last_index) {
5859 HeapRegion* curr_hr = region_at(i);
5860 assert(curr_hr->continuesHumongous(), "invariant");
5861 curr_hr->set_notHumongous();
5862 free_region(curr_hr, &hr_pre_used, free_list, par);
5863 i += 1;
5864 }
5865 assert(hr_pre_used == hr_used,
5866 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5867 "should be the same", hr_pre_used, hr_used));
5868 *pre_used += hr_pre_used;
5869 }
5870
5871 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5872 FreeRegionList* free_list,
5873 OldRegionSet* old_proxy_set,
5874 HumongousRegionSet* humongous_proxy_set,
5875 bool par) {
5876 if (pre_used > 0) {
5877 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5878 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5879 assert(_summary_bytes_used >= pre_used,
5880 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5881 "should be >= pre_used: "SIZE_FORMAT,
5882 _summary_bytes_used, pre_used));
5883 _summary_bytes_used -= pre_used;
5884 }
5885 if (free_list != NULL && !free_list->is_empty()) {
5886 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5887 _free_list.add_as_head(free_list);
5888 }
5889 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5890 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5891 _old_set.update_from_proxy(old_proxy_set);
5892 }
5893 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5894 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5895 _humongous_set.update_from_proxy(humongous_proxy_set);
5896 }
5897 }
5898
5899 class G1ParCleanupCTTask : public AbstractGangTask {
5900 CardTableModRefBS* _ct_bs;
5901 G1CollectedHeap* _g1h;
5902 HeapRegion* volatile _su_head;
5903 public:
5904 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5905 G1CollectedHeap* g1h) :
5906 AbstractGangTask("G1 Par Cleanup CT Task"),
5907 _ct_bs(ct_bs), _g1h(g1h) { }
5908
5909 void work(uint worker_id) {
5910 HeapRegion* r;
5911 while (r = _g1h->pop_dirty_cards_region()) {
5912 clear_cards(r);
5913 }
5914 }
5915
5916 void clear_cards(HeapRegion* r) {
5917 // Cards of the survivors should have already been dirtied.
5918 if (!r->is_survivor()) {
5919 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5920 }
5921 }
5922 };
5923
5924 #ifndef PRODUCT
5925 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5926 G1CollectedHeap* _g1h;
5927 CardTableModRefBS* _ct_bs;
5928 public:
5929 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5930 : _g1h(g1h), _ct_bs(ct_bs) { }
5931 virtual bool doHeapRegion(HeapRegion* r) {
5932 if (r->is_survivor()) {
5933 _g1h->verify_dirty_region(r);
5934 } else {
5935 _g1h->verify_not_dirty_region(r);
5936 }
5937 return false;
5938 }
5939 };
5940
5941 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5942 // All of the region should be clean.
5943 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5944 MemRegion mr(hr->bottom(), hr->end());
5945 ct_bs->verify_not_dirty_region(mr);
5946 }
5947
5948 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5949 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5950 // dirty allocated blocks as they allocate them. The thread that
5951 // retires each region and replaces it with a new one will do a
5952 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5953 // not dirty that area (one less thing to have to do while holding
5954 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5955 // is dirty.
5956 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5957 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5958 ct_bs->verify_dirty_region(mr);
5959 }
5960
5961 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5962 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5963 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5964 verify_dirty_region(hr);
5965 }
5966 }
5967
5968 void G1CollectedHeap::verify_dirty_young_regions() {
5969 verify_dirty_young_list(_young_list->first_region());
5970 }
5971 #endif
5972
5973 void G1CollectedHeap::cleanUpCardTable() {
5974 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5975 double start = os::elapsedTime();
5976
5977 {
5978 // Iterate over the dirty cards region list.
5979 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5980
5981 if (G1CollectedHeap::use_parallel_gc_threads()) {
5982 set_par_threads();
5983 workers()->run_task(&cleanup_task);
5984 set_par_threads(0);
5985 } else {
5986 while (_dirty_cards_region_list) {
5987 HeapRegion* r = _dirty_cards_region_list;
5988 cleanup_task.clear_cards(r);
5989 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5990 if (_dirty_cards_region_list == r) {
5991 // The last region.
5992 _dirty_cards_region_list = NULL;
5993 }
5994 r->set_next_dirty_cards_region(NULL);
5995 }
5996 }
5997 #ifndef PRODUCT
5998 if (G1VerifyCTCleanup || VerifyAfterGC) {
5999 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6000 heap_region_iterate(&cleanup_verifier);
6001 }
6002 #endif
6003 }
6004
6005 double elapsed = os::elapsedTime() - start;
6006 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6007 }
6008
6009 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6010 size_t pre_used = 0;
6011 FreeRegionList local_free_list("Local List for CSet Freeing");
6012
6013 double young_time_ms = 0.0;
6014 double non_young_time_ms = 0.0;
6015
6016 // Since the collection set is a superset of the the young list,
6017 // all we need to do to clear the young list is clear its
6018 // head and length, and unlink any young regions in the code below
6019 _young_list->clear();
6020
6021 G1CollectorPolicy* policy = g1_policy();
6022
6023 double start_sec = os::elapsedTime();
6024 bool non_young = true;
6025
6026 HeapRegion* cur = cs_head;
6027 int age_bound = -1;
6028 size_t rs_lengths = 0;
6029
6030 while (cur != NULL) {
6031 assert(!is_on_master_free_list(cur), "sanity");
6032 if (non_young) {
6033 if (cur->is_young()) {
6034 double end_sec = os::elapsedTime();
6035 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6036 non_young_time_ms += elapsed_ms;
6037
6038 start_sec = os::elapsedTime();
6039 non_young = false;
6040 }
6041 } else {
6042 if (!cur->is_young()) {
6043 double end_sec = os::elapsedTime();
6044 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6045 young_time_ms += elapsed_ms;
6046
6047 start_sec = os::elapsedTime();
6048 non_young = true;
6049 }
6050 }
6051
6052 rs_lengths += cur->rem_set()->occupied();
6053
6054 HeapRegion* next = cur->next_in_collection_set();
6055 assert(cur->in_collection_set(), "bad CS");
6056 cur->set_next_in_collection_set(NULL);
6057 cur->set_in_collection_set(false);
6058
6059 if (cur->is_young()) {
6060 int index = cur->young_index_in_cset();
6061 assert(index != -1, "invariant");
6062 assert((uint) index < policy->young_cset_region_length(), "invariant");
6063 size_t words_survived = _surviving_young_words[index];
6064 cur->record_surv_words_in_group(words_survived);
6065
6066 // At this point the we have 'popped' cur from the collection set
6067 // (linked via next_in_collection_set()) but it is still in the
6068 // young list (linked via next_young_region()). Clear the
6069 // _next_young_region field.
6070 cur->set_next_young_region(NULL);
6071 } else {
6072 int index = cur->young_index_in_cset();
6073 assert(index == -1, "invariant");
6074 }
6075
6076 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6077 (!cur->is_young() && cur->young_index_in_cset() == -1),
6078 "invariant" );
6079
6080 if (!cur->evacuation_failed()) {
6081 MemRegion used_mr = cur->used_region();
6082
6083 // And the region is empty.
6084 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6085 free_region(cur, &pre_used, &local_free_list, false /* par */);
6086 } else {
6087 cur->uninstall_surv_rate_group();
6088 if (cur->is_young()) {
6089 cur->set_young_index_in_cset(-1);
6090 }
6091 cur->set_not_young();
6092 cur->set_evacuation_failed(false);
6093 // The region is now considered to be old.
6094 _old_set.add(cur);
6095 evacuation_info.increment_collectionset_used_after(cur->used());
6096 }
6097 cur = next;
6098 }
6099
6100 evacuation_info.set_regions_freed(local_free_list.length());
6101 policy->record_max_rs_lengths(rs_lengths);
6102 policy->cset_regions_freed();
6103
6104 double end_sec = os::elapsedTime();
6105 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6106
6107 if (non_young) {
6108 non_young_time_ms += elapsed_ms;
6109 } else {
6110 young_time_ms += elapsed_ms;
6111 }
6112
6113 update_sets_after_freeing_regions(pre_used, &local_free_list,
6114 NULL /* old_proxy_set */,
6115 NULL /* humongous_proxy_set */,
6116 false /* par */);
6117 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6118 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6119 }
6120
6121 // This routine is similar to the above but does not record
6122 // any policy statistics or update free lists; we are abandoning
6123 // the current incremental collection set in preparation of a
6124 // full collection. After the full GC we will start to build up
6125 // the incremental collection set again.
6126 // This is only called when we're doing a full collection
6127 // and is immediately followed by the tearing down of the young list.
6128
6129 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6130 HeapRegion* cur = cs_head;
6131
6132 while (cur != NULL) {
6133 HeapRegion* next = cur->next_in_collection_set();
6134 assert(cur->in_collection_set(), "bad CS");
6135 cur->set_next_in_collection_set(NULL);
6136 cur->set_in_collection_set(false);
6137 cur->set_young_index_in_cset(-1);
6138 cur = next;
6139 }
6140 }
6141
6142 void G1CollectedHeap::set_free_regions_coming() {
6143 if (G1ConcRegionFreeingVerbose) {
6144 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6145 "setting free regions coming");
6146 }
6147
6148 assert(!free_regions_coming(), "pre-condition");
6149 _free_regions_coming = true;
6150 }
6151
6152 void G1CollectedHeap::reset_free_regions_coming() {
6153 assert(free_regions_coming(), "pre-condition");
6154
6155 {
6156 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6157 _free_regions_coming = false;
6158 SecondaryFreeList_lock->notify_all();
6159 }
6160
6161 if (G1ConcRegionFreeingVerbose) {
6162 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6163 "reset free regions coming");
6164 }
6165 }
6166
6167 void G1CollectedHeap::wait_while_free_regions_coming() {
6168 // Most of the time we won't have to wait, so let's do a quick test
6169 // first before we take the lock.
6170 if (!free_regions_coming()) {
6171 return;
6172 }
6173
6174 if (G1ConcRegionFreeingVerbose) {
6175 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6176 "waiting for free regions");
6177 }
6178
6179 {
6180 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6181 while (free_regions_coming()) {
6182 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6183 }
6184 }
6185
6186 if (G1ConcRegionFreeingVerbose) {
6187 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6188 "done waiting for free regions");
6189 }
6190 }
6191
6192 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6193 assert(heap_lock_held_for_gc(),
6194 "the heap lock should already be held by or for this thread");
6195 _young_list->push_region(hr);
6196 }
6197
6198 class NoYoungRegionsClosure: public HeapRegionClosure {
6199 private:
6200 bool _success;
6201 public:
6202 NoYoungRegionsClosure() : _success(true) { }
6203 bool doHeapRegion(HeapRegion* r) {
6204 if (r->is_young()) {
6205 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6206 r->bottom(), r->end());
6207 _success = false;
6208 }
6209 return false;
6210 }
6211 bool success() { return _success; }
6212 };
6213
6214 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6215 bool ret = _young_list->check_list_empty(check_sample);
6216
6217 if (check_heap) {
6218 NoYoungRegionsClosure closure;
6219 heap_region_iterate(&closure);
6220 ret = ret && closure.success();
6221 }
6222
6223 return ret;
6224 }
6225
6226 class TearDownRegionSetsClosure : public HeapRegionClosure {
6227 private:
6228 OldRegionSet *_old_set;
6229
6230 public:
6231 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6232
6233 bool doHeapRegion(HeapRegion* r) {
6234 if (r->is_empty()) {
6235 // We ignore empty regions, we'll empty the free list afterwards
6236 } else if (r->is_young()) {
6237 // We ignore young regions, we'll empty the young list afterwards
6238 } else if (r->isHumongous()) {
6239 // We ignore humongous regions, we're not tearing down the
6240 // humongous region set
6241 } else {
6242 // The rest should be old
6243 _old_set->remove(r);
6244 }
6245 return false;
6246 }
6247
6248 ~TearDownRegionSetsClosure() {
6249 assert(_old_set->is_empty(), "post-condition");
6250 }
6251 };
6252
6253 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6254 assert_at_safepoint(true /* should_be_vm_thread */);
6255
6256 if (!free_list_only) {
6257 TearDownRegionSetsClosure cl(&_old_set);
6258 heap_region_iterate(&cl);
6259
6260 // Need to do this after the heap iteration to be able to
6261 // recognize the young regions and ignore them during the iteration.
6262 _young_list->empty_list();
6263 }
6264 _free_list.remove_all();
6265 }
6266
6267 class RebuildRegionSetsClosure : public HeapRegionClosure {
6268 private:
6269 bool _free_list_only;
6270 OldRegionSet* _old_set;
6271 FreeRegionList* _free_list;
6272 size_t _total_used;
6273
6274 public:
6275 RebuildRegionSetsClosure(bool free_list_only,
6276 OldRegionSet* old_set, FreeRegionList* free_list) :
6277 _free_list_only(free_list_only),
6278 _old_set(old_set), _free_list(free_list), _total_used(0) {
6279 assert(_free_list->is_empty(), "pre-condition");
6280 if (!free_list_only) {
6281 assert(_old_set->is_empty(), "pre-condition");
6282 }
6283 }
6284
6285 bool doHeapRegion(HeapRegion* r) {
6286 if (r->continuesHumongous()) {
6287 return false;
6288 }
6289
6290 if (r->is_empty()) {
6291 // Add free regions to the free list
6292 _free_list->add_as_tail(r);
6293 } else if (!_free_list_only) {
6294 assert(!r->is_young(), "we should not come across young regions");
6295
6296 if (r->isHumongous()) {
6297 // We ignore humongous regions, we left the humongous set unchanged
6298 } else {
6299 // The rest should be old, add them to the old set
6300 _old_set->add(r);
6301 }
6302 _total_used += r->used();
6303 }
6304
6305 return false;
6306 }
6307
6308 size_t total_used() {
6309 return _total_used;
6310 }
6311 };
6312
6313 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6314 assert_at_safepoint(true /* should_be_vm_thread */);
6315
6316 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6317 heap_region_iterate(&cl);
6318
6319 if (!free_list_only) {
6320 _summary_bytes_used = cl.total_used();
6321 }
6322 assert(_summary_bytes_used == recalculate_used(),
6323 err_msg("inconsistent _summary_bytes_used, "
6324 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6325 _summary_bytes_used, recalculate_used()));
6326 }
6327
6328 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6329 _refine_cte_cl->set_concurrent(concurrent);
6330 }
6331
6332 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6333 HeapRegion* hr = heap_region_containing(p);
6334 if (hr == NULL) {
6335 return is_in_permanent(p);
6336 } else {
6337 return hr->is_in(p);
6338 }
6339 }
6340
6341 // Methods for the mutator alloc region
6342
6343 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6344 bool force) {
6345 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6346 assert(!force || g1_policy()->can_expand_young_list(),
6347 "if force is true we should be able to expand the young list");
6348 bool young_list_full = g1_policy()->is_young_list_full();
6349 if (force || !young_list_full) {
6350 HeapRegion* new_alloc_region = new_region(word_size,
6351 false /* do_expand */);
6352 if (new_alloc_region != NULL) {
6353 set_region_short_lived_locked(new_alloc_region);
6354 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6355 return new_alloc_region;
6356 }
6357 }
6358 return NULL;
6359 }
6360
6361 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6362 size_t allocated_bytes) {
6363 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6364 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6365
6366 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6367 _summary_bytes_used += allocated_bytes;
6368 _hr_printer.retire(alloc_region);
6369 // We update the eden sizes here, when the region is retired,
6370 // instead of when it's allocated, since this is the point that its
6371 // used space has been recored in _summary_bytes_used.
6372 g1mm()->update_eden_size();
6373 }
6374
6375 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6376 bool force) {
6377 return _g1h->new_mutator_alloc_region(word_size, force);
6378 }
6379
6380 void G1CollectedHeap::set_par_threads() {
6381 // Don't change the number of workers. Use the value previously set
6382 // in the workgroup.
6383 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6384 uint n_workers = workers()->active_workers();
6385 assert(UseDynamicNumberOfGCThreads ||
6386 n_workers == workers()->total_workers(),
6387 "Otherwise should be using the total number of workers");
6388 if (n_workers == 0) {
6389 assert(false, "Should have been set in prior evacuation pause.");
6390 n_workers = ParallelGCThreads;
6391 workers()->set_active_workers(n_workers);
6392 }
6393 set_par_threads(n_workers);
6394 }
6395
6396 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6397 size_t allocated_bytes) {
6398 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6399 }
6400
6401 // Methods for the GC alloc regions
6402
6403 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6404 uint count,
6405 GCAllocPurpose ap) {
6406 assert(FreeList_lock->owned_by_self(), "pre-condition");
6407
6408 if (count < g1_policy()->max_regions(ap)) {
6409 HeapRegion* new_alloc_region = new_region(word_size,
6410 true /* do_expand */);
6411 if (new_alloc_region != NULL) {
6412 // We really only need to do this for old regions given that we
6413 // should never scan survivors. But it doesn't hurt to do it
6414 // for survivors too.
6415 new_alloc_region->set_saved_mark();
6416 if (ap == GCAllocForSurvived) {
6417 new_alloc_region->set_survivor();
6418 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6419 } else {
6420 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6421 }
6422 bool during_im = g1_policy()->during_initial_mark_pause();
6423 new_alloc_region->note_start_of_copying(during_im);
6424 return new_alloc_region;
6425 } else {
6426 g1_policy()->note_alloc_region_limit_reached(ap);
6427 }
6428 }
6429 return NULL;
6430 }
6431
6432 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6433 size_t allocated_bytes,
6434 GCAllocPurpose ap) {
6435 bool during_im = g1_policy()->during_initial_mark_pause();
6436 alloc_region->note_end_of_copying(during_im);
6437 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6438 if (ap == GCAllocForSurvived) {
6439 young_list()->add_survivor_region(alloc_region);
6440 } else {
6441 _old_set.add(alloc_region);
6442 }
6443 _hr_printer.retire(alloc_region);
6444 }
6445
6446 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6447 bool force) {
6448 assert(!force, "not supported for GC alloc regions");
6449 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6450 }
6451
6452 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6453 size_t allocated_bytes) {
6454 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6455 GCAllocForSurvived);
6456 }
6457
6458 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6459 bool force) {
6460 assert(!force, "not supported for GC alloc regions");
6461 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6462 }
6463
6464 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6465 size_t allocated_bytes) {
6466 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6467 GCAllocForTenured);
6468 }
6469 // Heap region set verification
6470
6471 class VerifyRegionListsClosure : public HeapRegionClosure {
6472 private:
6473 FreeRegionList* _free_list;
6474 OldRegionSet* _old_set;
6475 HumongousRegionSet* _humongous_set;
6476 uint _region_count;
6477
6478 public:
6479 VerifyRegionListsClosure(OldRegionSet* old_set,
6480 HumongousRegionSet* humongous_set,
6481 FreeRegionList* free_list) :
6482 _old_set(old_set), _humongous_set(humongous_set),
6483 _free_list(free_list), _region_count(0) { }
6484
6485 uint region_count() { return _region_count; }
6486
6487 bool doHeapRegion(HeapRegion* hr) {
6488 _region_count += 1;
6489
6490 if (hr->continuesHumongous()) {
6491 return false;
6492 }
6493
6494 if (hr->is_young()) {
6495 // TODO
6496 } else if (hr->startsHumongous()) {
6497 _humongous_set->verify_next_region(hr);
6498 } else if (hr->is_empty()) {
6499 _free_list->verify_next_region(hr);
6500 } else {
6501 _old_set->verify_next_region(hr);
6502 }
6503 return false;
6504 }
6505 };
6506
6507 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6508 HeapWord* bottom) {
6509 HeapWord* end = bottom + HeapRegion::GrainWords;
6510 MemRegion mr(bottom, end);
6511 assert(_g1_reserved.contains(mr), "invariant");
6512 // This might return NULL if the allocation fails
6513 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6514 }
6515
6516 void G1CollectedHeap::verify_region_sets() {
6517 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6518
6519 // First, check the explicit lists.
6520 _free_list.verify();
6521 {
6522 // Given that a concurrent operation might be adding regions to
6523 // the secondary free list we have to take the lock before
6524 // verifying it.
6525 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6526 _secondary_free_list.verify();
6527 }
6528 _old_set.verify();
6529 _humongous_set.verify();
6530
6531 // If a concurrent region freeing operation is in progress it will
6532 // be difficult to correctly attributed any free regions we come
6533 // across to the correct free list given that they might belong to
6534 // one of several (free_list, secondary_free_list, any local lists,
6535 // etc.). So, if that's the case we will skip the rest of the
6536 // verification operation. Alternatively, waiting for the concurrent
6537 // operation to complete will have a non-trivial effect on the GC's
6538 // operation (no concurrent operation will last longer than the
6539 // interval between two calls to verification) and it might hide
6540 // any issues that we would like to catch during testing.
6541 if (free_regions_coming()) {
6542 return;
6543 }
6544
6545 // Make sure we append the secondary_free_list on the free_list so
6546 // that all free regions we will come across can be safely
6547 // attributed to the free_list.
6548 append_secondary_free_list_if_not_empty_with_lock();
6549
6550 // Finally, make sure that the region accounting in the lists is
6551 // consistent with what we see in the heap.
6552 _old_set.verify_start();
6553 _humongous_set.verify_start();
6554 _free_list.verify_start();
6555
6556 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6557 heap_region_iterate(&cl);
6558
6559 _old_set.verify_end();
6560 _humongous_set.verify_end();
6561 _free_list.verify_end();
6562 }