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/vmThread.hpp"
58
59 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
60
61 // turn it on so that the contents of the young list (scan-only /
62 // to-be-collected) are printed at "strategic" points before / during
63 // / after the collection --- this is useful for debugging
64 #define YOUNG_LIST_VERBOSE 0
65 // CURRENT STATUS
66 // This file is under construction. Search for "FIXME".
67
68 // INVARIANTS/NOTES
69 //
70 // All allocation activity covered by the G1CollectedHeap interface is
71 // serialized by acquiring the HeapLock. This happens in mem_allocate
72 // and allocate_new_tlab, which are the "entry" points to the
73 // allocation code from the rest of the JVM. (Note that this does not
74 // apply to TLAB allocation, which is not part of this interface: it
75 // is done by clients of this interface.)
76
77 // Notes on implementation of parallelism in different tasks.
78 //
79 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
80 // The number of GC workers is passed to heap_region_par_iterate_chunked().
81 // It does use run_task() which sets _n_workers in the task.
82 // G1ParTask executes g1_process_strong_roots() ->
83 // SharedHeap::process_strong_roots() which calls eventually to
84 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
85 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
86 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
87 //
88
89 // Local to this file.
90
91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
92 SuspendibleThreadSet* _sts;
93 G1RemSet* _g1rs;
94 ConcurrentG1Refine* _cg1r;
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
98 G1RemSet* g1rs,
99 ConcurrentG1Refine* cg1r) :
100 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
101 {}
102 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
103 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
104 // This path is executed by the concurrent refine or mutator threads,
105 // concurrently, and so we do not care if card_ptr contains references
106 // that point into the collection set.
107 assert(!oops_into_cset, "should be");
108
109 if (_concurrent && _sts->should_yield()) {
110 // Caller will actually yield.
111 return false;
112 }
113 // Otherwise, we finished successfully; return true.
114 return true;
115 }
116 void set_concurrent(bool b) { _concurrent = b; }
117 };
118
119
120 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
121 int _calls;
122 G1CollectedHeap* _g1h;
123 CardTableModRefBS* _ctbs;
124 int _histo[256];
125 public:
126 ClearLoggedCardTableEntryClosure() :
127 _calls(0)
128 {
129 _g1h = G1CollectedHeap::heap();
130 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
131 for (int i = 0; i < 256; i++) _histo[i] = 0;
132 }
133 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
134 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
135 _calls++;
136 unsigned char* ujb = (unsigned char*)card_ptr;
137 int ind = (int)(*ujb);
138 _histo[ind]++;
139 *card_ptr = -1;
140 }
141 return true;
142 }
143 int calls() { return _calls; }
144 void print_histo() {
145 gclog_or_tty->print_cr("Card table value histogram:");
146 for (int i = 0; i < 256; i++) {
147 if (_histo[i] != 0) {
148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
149 }
150 }
151 }
152 };
153
154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
155 int _calls;
156 G1CollectedHeap* _g1h;
157 CardTableModRefBS* _ctbs;
158 public:
159 RedirtyLoggedCardTableEntryClosure() :
160 _calls(0)
161 {
162 _g1h = G1CollectedHeap::heap();
163 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
164 }
165 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
166 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
167 _calls++;
168 *card_ptr = 0;
169 }
170 return true;
171 }
172 int calls() { return _calls; }
173 };
174
175 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
176 public:
177 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
178 *card_ptr = CardTableModRefBS::dirty_card_val();
179 return true;
180 }
181 };
182
183 YoungList::YoungList(G1CollectedHeap* g1h) :
184 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
185 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
186 guarantee(check_list_empty(false), "just making sure...");
187 }
188
189 void YoungList::push_region(HeapRegion *hr) {
190 assert(!hr->is_young(), "should not already be young");
191 assert(hr->get_next_young_region() == NULL, "cause it should!");
192
193 hr->set_next_young_region(_head);
194 _head = hr;
195
196 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
197 ++_length;
198 }
199
200 void YoungList::add_survivor_region(HeapRegion* hr) {
201 assert(hr->is_survivor(), "should be flagged as survivor region");
202 assert(hr->get_next_young_region() == NULL, "cause it should!");
203
204 hr->set_next_young_region(_survivor_head);
205 if (_survivor_head == NULL) {
206 _survivor_tail = hr;
207 }
208 _survivor_head = hr;
209 ++_survivor_length;
210 }
211
212 void YoungList::empty_list(HeapRegion* list) {
213 while (list != NULL) {
214 HeapRegion* next = list->get_next_young_region();
215 list->set_next_young_region(NULL);
216 list->uninstall_surv_rate_group();
217 list->set_not_young();
218 list = next;
219 }
220 }
221
222 void YoungList::empty_list() {
223 assert(check_list_well_formed(), "young list should be well formed");
224
225 empty_list(_head);
226 _head = NULL;
227 _length = 0;
228
229 empty_list(_survivor_head);
230 _survivor_head = NULL;
231 _survivor_tail = NULL;
232 _survivor_length = 0;
233
234 _last_sampled_rs_lengths = 0;
235
236 assert(check_list_empty(false), "just making sure...");
237 }
238
239 bool YoungList::check_list_well_formed() {
240 bool ret = true;
241
242 uint length = 0;
243 HeapRegion* curr = _head;
244 HeapRegion* last = NULL;
245 while (curr != NULL) {
246 if (!curr->is_young()) {
247 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
248 "incorrectly tagged (y: %d, surv: %d)",
249 curr->bottom(), curr->end(),
250 curr->is_young(), curr->is_survivor());
251 ret = false;
252 }
253 ++length;
254 last = curr;
255 curr = curr->get_next_young_region();
256 }
257 ret = ret && (length == _length);
258
259 if (!ret) {
260 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
261 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
262 length, _length);
263 }
264
265 return ret;
266 }
267
268 bool YoungList::check_list_empty(bool check_sample) {
269 bool ret = true;
270
271 if (_length != 0) {
272 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
273 _length);
274 ret = false;
275 }
276 if (check_sample && _last_sampled_rs_lengths != 0) {
277 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
278 ret = false;
279 }
280 if (_head != NULL) {
281 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
282 ret = false;
283 }
284 if (!ret) {
285 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
286 }
287
288 return ret;
289 }
290
291 void
292 YoungList::rs_length_sampling_init() {
293 _sampled_rs_lengths = 0;
294 _curr = _head;
295 }
296
297 bool
298 YoungList::rs_length_sampling_more() {
299 return _curr != NULL;
300 }
301
302 void
303 YoungList::rs_length_sampling_next() {
304 assert( _curr != NULL, "invariant" );
305 size_t rs_length = _curr->rem_set()->occupied();
306
307 _sampled_rs_lengths += rs_length;
308
309 // The current region may not yet have been added to the
310 // incremental collection set (it gets added when it is
311 // retired as the current allocation region).
312 if (_curr->in_collection_set()) {
313 // Update the collection set policy information for this region
314 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
315 }
316
317 _curr = _curr->get_next_young_region();
318 if (_curr == NULL) {
319 _last_sampled_rs_lengths = _sampled_rs_lengths;
320 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
321 }
322 }
323
324 void
325 YoungList::reset_auxilary_lists() {
326 guarantee( is_empty(), "young list should be empty" );
327 assert(check_list_well_formed(), "young list should be well formed");
328
329 // Add survivor regions to SurvRateGroup.
330 _g1h->g1_policy()->note_start_adding_survivor_regions();
331 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
332
333 int young_index_in_cset = 0;
334 for (HeapRegion* curr = _survivor_head;
335 curr != NULL;
336 curr = curr->get_next_young_region()) {
337 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
338
339 // The region is a non-empty survivor so let's add it to
340 // the incremental collection set for the next evacuation
341 // pause.
342 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
343 young_index_in_cset += 1;
344 }
345 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
346 _g1h->g1_policy()->note_stop_adding_survivor_regions();
347
348 _head = _survivor_head;
349 _length = _survivor_length;
350 if (_survivor_head != NULL) {
351 assert(_survivor_tail != NULL, "cause it shouldn't be");
352 assert(_survivor_length > 0, "invariant");
353 _survivor_tail->set_next_young_region(NULL);
354 }
355
356 // Don't clear the survivor list handles until the start of
357 // the next evacuation pause - we need it in order to re-tag
358 // the survivor regions from this evacuation pause as 'young'
359 // at the start of the next.
360
361 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
362
363 assert(check_list_well_formed(), "young list should be well formed");
364 }
365
366 void YoungList::print() {
367 HeapRegion* lists[] = {_head, _survivor_head};
368 const char* names[] = {"YOUNG", "SURVIVOR"};
369
370 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
371 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
372 HeapRegion *curr = lists[list];
373 if (curr == NULL)
374 gclog_or_tty->print_cr(" empty");
375 while (curr != NULL) {
376 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
377 HR_FORMAT_PARAMS(curr),
378 curr->prev_top_at_mark_start(),
379 curr->next_top_at_mark_start(),
380 curr->age_in_surv_rate_group_cond());
381 curr = curr->get_next_young_region();
382 }
383 }
384
385 gclog_or_tty->print_cr("");
386 }
387
388 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
389 {
390 // Claim the right to put the region on the dirty cards region list
391 // by installing a self pointer.
392 HeapRegion* next = hr->get_next_dirty_cards_region();
393 if (next == NULL) {
394 HeapRegion* res = (HeapRegion*)
395 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
396 NULL);
397 if (res == NULL) {
398 HeapRegion* head;
399 do {
400 // Put the region to the dirty cards region list.
401 head = _dirty_cards_region_list;
402 next = (HeapRegion*)
403 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
404 if (next == head) {
405 assert(hr->get_next_dirty_cards_region() == hr,
406 "hr->get_next_dirty_cards_region() != hr");
407 if (next == NULL) {
408 // The last region in the list points to itself.
409 hr->set_next_dirty_cards_region(hr);
410 } else {
411 hr->set_next_dirty_cards_region(next);
412 }
413 }
414 } while (next != head);
415 }
416 }
417 }
418
419 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
420 {
421 HeapRegion* head;
422 HeapRegion* hr;
423 do {
424 head = _dirty_cards_region_list;
425 if (head == NULL) {
426 return NULL;
427 }
428 HeapRegion* new_head = head->get_next_dirty_cards_region();
429 if (head == new_head) {
430 // The last region.
431 new_head = NULL;
432 }
433 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
434 head);
435 } while (hr != head);
436 assert(hr != NULL, "invariant");
437 hr->set_next_dirty_cards_region(NULL);
438 return hr;
439 }
440
441 void G1CollectedHeap::stop_conc_gc_threads() {
442 _cg1r->stop();
443 _cmThread->stop();
444 }
445
446 #ifdef ASSERT
447 // A region is added to the collection set as it is retired
448 // so an address p can point to a region which will be in the
449 // collection set but has not yet been retired. This method
450 // therefore is only accurate during a GC pause after all
451 // regions have been retired. It is used for debugging
452 // to check if an nmethod has references to objects that can
453 // be move during a partial collection. Though it can be
454 // inaccurate, it is sufficient for G1 because the conservative
455 // implementation of is_scavengable() for G1 will indicate that
456 // all nmethods must be scanned during a partial collection.
457 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
458 HeapRegion* hr = heap_region_containing(p);
459 return hr != NULL && hr->in_collection_set();
460 }
461 #endif
462
463 // Returns true if the reference points to an object that
464 // can move in an incremental collection.
465 bool G1CollectedHeap::is_scavengable(const void* p) {
466 G1CollectedHeap* g1h = G1CollectedHeap::heap();
467 G1CollectorPolicy* g1p = g1h->g1_policy();
468 HeapRegion* hr = heap_region_containing(p);
469 if (hr == NULL) {
470 // null
471 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
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 int dummy_gclocker_retry_count = 0;
862 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
863 }
864
865 HeapWord*
866 G1CollectedHeap::mem_allocate(size_t word_size,
867 bool* gc_overhead_limit_was_exceeded) {
868 assert_heap_not_locked_and_not_at_safepoint();
869
870 // Loop until the allocation is satisfied, or unsatisfied after GC.
871 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
872 unsigned int gc_count_before;
873
874 HeapWord* result = NULL;
875 if (!isHumongous(word_size)) {
876 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
877 } else {
878 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
879 }
880 if (result != NULL) {
881 return result;
882 }
883
884 // Create the garbage collection operation...
885 VM_G1CollectForAllocation op(gc_count_before, word_size);
886 // ...and get the VM thread to execute it.
887 VMThread::execute(&op);
888
889 if (op.prologue_succeeded() && op.pause_succeeded()) {
890 // If the operation was successful we'll return the result even
891 // if it is NULL. If the allocation attempt failed immediately
892 // after a Full GC, it's unlikely we'll be able to allocate now.
893 HeapWord* result = op.result();
894 if (result != NULL && !isHumongous(word_size)) {
895 // Allocations that take place on VM operations do not do any
896 // card dirtying and we have to do it here. We only have to do
897 // this for non-humongous allocations, though.
898 dirty_young_block(result, word_size);
899 }
900 return result;
901 } else {
902 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
903 return NULL;
904 }
905 assert(op.result() == NULL,
906 "the result should be NULL if the VM op did not succeed");
907 }
908
909 // Give a warning if we seem to be looping forever.
910 if ((QueuedAllocationWarningCount > 0) &&
911 (try_count % QueuedAllocationWarningCount == 0)) {
912 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
913 }
914 }
915
916 ShouldNotReachHere();
917 return NULL;
918 }
919
920 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
921 unsigned int *gc_count_before_ret,
922 int* gclocker_retry_count_ret) {
923 // Make sure you read the note in attempt_allocation_humongous().
924
925 assert_heap_not_locked_and_not_at_safepoint();
926 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
927 "be called for humongous allocation requests");
928
929 // We should only get here after the first-level allocation attempt
930 // (attempt_allocation()) failed to allocate.
931
932 // We will loop until a) we manage to successfully perform the
933 // allocation or b) we successfully schedule a collection which
934 // fails to perform the allocation. b) is the only case when we'll
935 // return NULL.
936 HeapWord* result = NULL;
937 for (int try_count = 1; /* we'll return */; try_count += 1) {
938 bool should_try_gc;
939 unsigned int gc_count_before;
940
941 {
942 MutexLockerEx x(Heap_lock);
943
944 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
945 false /* bot_updates */);
946 if (result != NULL) {
947 return result;
948 }
949
950 // If we reach here, attempt_allocation_locked() above failed to
951 // allocate a new region. So the mutator alloc region should be NULL.
952 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
953
954 if (GC_locker::is_active_and_needs_gc()) {
955 if (g1_policy()->can_expand_young_list()) {
956 // No need for an ergo verbose message here,
957 // can_expand_young_list() does this when it returns true.
958 result = _mutator_alloc_region.attempt_allocation_force(word_size,
959 false /* bot_updates */);
960 if (result != NULL) {
961 return result;
962 }
963 }
964 should_try_gc = false;
965 } else {
966 // The GCLocker may not be active but the GCLocker initiated
967 // GC may not yet have been performed (GCLocker::needs_gc()
968 // returns true). In this case we do not try this GC and
969 // wait until the GCLocker initiated GC is performed, and
970 // then retry the allocation.
971 if (GC_locker::needs_gc()) {
972 should_try_gc = false;
973 } else {
974 // Read the GC count while still holding the Heap_lock.
975 gc_count_before = total_collections();
976 should_try_gc = true;
977 }
978 }
979 }
980
981 if (should_try_gc) {
982 bool succeeded;
983 result = do_collection_pause(word_size, gc_count_before, &succeeded);
984 if (result != NULL) {
985 assert(succeeded, "only way to get back a non-NULL result");
986 return result;
987 }
988
989 if (succeeded) {
990 // If we get here we successfully scheduled a collection which
991 // failed to allocate. No point in trying to allocate
992 // further. We'll just return NULL.
993 MutexLockerEx x(Heap_lock);
994 *gc_count_before_ret = total_collections();
995 return NULL;
996 }
997 } else {
998 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
999 MutexLockerEx x(Heap_lock);
1000 *gc_count_before_ret = total_collections();
1001 return NULL;
1002 }
1003 // The GCLocker is either active or the GCLocker initiated
1004 // GC has not yet been performed. Stall until it is and
1005 // then retry the allocation.
1006 GC_locker::stall_until_clear();
1007 (*gclocker_retry_count_ret) += 1;
1008 }
1009
1010 // We can reach here if we were unsuccessful in scheduling a
1011 // collection (because another thread beat us to it) or if we were
1012 // stalled due to the GC locker. In either can we should retry the
1013 // allocation attempt in case another thread successfully
1014 // performed a collection and reclaimed enough space. We do the
1015 // first attempt (without holding the Heap_lock) here and the
1016 // follow-on attempt will be at the start of the next loop
1017 // iteration (after taking the Heap_lock).
1018 result = _mutator_alloc_region.attempt_allocation(word_size,
1019 false /* bot_updates */);
1020 if (result != NULL) {
1021 return result;
1022 }
1023
1024 // Give a warning if we seem to be looping forever.
1025 if ((QueuedAllocationWarningCount > 0) &&
1026 (try_count % QueuedAllocationWarningCount == 0)) {
1027 warning("G1CollectedHeap::attempt_allocation_slow() "
1028 "retries %d times", try_count);
1029 }
1030 }
1031
1032 ShouldNotReachHere();
1033 return NULL;
1034 }
1035
1036 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1037 unsigned int * gc_count_before_ret,
1038 int* gclocker_retry_count_ret) {
1039 // The structure of this method has a lot of similarities to
1040 // attempt_allocation_slow(). The reason these two were not merged
1041 // into a single one is that such a method would require several "if
1042 // allocation is not humongous do this, otherwise do that"
1043 // conditional paths which would obscure its flow. In fact, an early
1044 // version of this code did use a unified method which was harder to
1045 // follow and, as a result, it had subtle bugs that were hard to
1046 // track down. So keeping these two methods separate allows each to
1047 // be more readable. It will be good to keep these two in sync as
1048 // much as possible.
1049
1050 assert_heap_not_locked_and_not_at_safepoint();
1051 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1052 "should only be called for humongous allocations");
1053
1054 // Humongous objects can exhaust the heap quickly, so we should check if we
1055 // need to start a marking cycle at each humongous object allocation. We do
1056 // the check before we do the actual allocation. The reason for doing it
1057 // before the allocation is that we avoid having to keep track of the newly
1058 // allocated memory while we do a GC.
1059 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1060 word_size)) {
1061 collect(GCCause::_g1_humongous_allocation);
1062 }
1063
1064 // We will loop until a) we manage to successfully perform the
1065 // allocation or b) we successfully schedule a collection which
1066 // fails to perform the allocation. b) is the only case when we'll
1067 // return NULL.
1068 HeapWord* result = NULL;
1069 for (int try_count = 1; /* we'll return */; try_count += 1) {
1070 bool should_try_gc;
1071 unsigned int gc_count_before;
1072
1073 {
1074 MutexLockerEx x(Heap_lock);
1075
1076 // Given that humongous objects are not allocated in young
1077 // regions, we'll first try to do the allocation without doing a
1078 // collection hoping that there's enough space in the heap.
1079 result = humongous_obj_allocate(word_size);
1080 if (result != NULL) {
1081 return result;
1082 }
1083
1084 if (GC_locker::is_active_and_needs_gc()) {
1085 should_try_gc = false;
1086 } else {
1087 // The GCLocker may not be active but the GCLocker initiated
1088 // GC may not yet have been performed (GCLocker::needs_gc()
1089 // returns true). In this case we do not try this GC and
1090 // wait until the GCLocker initiated GC is performed, and
1091 // then retry the allocation.
1092 if (GC_locker::needs_gc()) {
1093 should_try_gc = false;
1094 } else {
1095 // Read the GC count while still holding the Heap_lock.
1096 gc_count_before = total_collections();
1097 should_try_gc = true;
1098 }
1099 }
1100 }
1101
1102 if (should_try_gc) {
1103 // If we failed to allocate the humongous object, we should try to
1104 // do a collection pause (if we're allowed) in case it reclaims
1105 // enough space for the allocation to succeed after the pause.
1106
1107 bool succeeded;
1108 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1109 if (result != NULL) {
1110 assert(succeeded, "only way to get back a non-NULL result");
1111 return result;
1112 }
1113
1114 if (succeeded) {
1115 // If we get here we successfully scheduled a collection which
1116 // failed to allocate. No point in trying to allocate
1117 // further. We'll just return NULL.
1118 MutexLockerEx x(Heap_lock);
1119 *gc_count_before_ret = total_collections();
1120 return NULL;
1121 }
1122 } else {
1123 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1124 MutexLockerEx x(Heap_lock);
1125 *gc_count_before_ret = total_collections();
1126 return NULL;
1127 }
1128 // The GCLocker is either active or the GCLocker initiated
1129 // GC has not yet been performed. Stall until it is and
1130 // then retry the allocation.
1131 GC_locker::stall_until_clear();
1132 (*gclocker_retry_count_ret) += 1;
1133 }
1134
1135 // We can reach here if we were unsuccessful in scheduling a
1136 // collection (because another thread beat us to it) or if we were
1137 // stalled due to the GC locker. In either can we should retry the
1138 // allocation attempt in case another thread successfully
1139 // performed a collection and reclaimed enough space. Give a
1140 // warning if we seem to be looping forever.
1141
1142 if ((QueuedAllocationWarningCount > 0) &&
1143 (try_count % QueuedAllocationWarningCount == 0)) {
1144 warning("G1CollectedHeap::attempt_allocation_humongous() "
1145 "retries %d times", try_count);
1146 }
1147 }
1148
1149 ShouldNotReachHere();
1150 return NULL;
1151 }
1152
1153 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1154 bool expect_null_mutator_alloc_region) {
1155 assert_at_safepoint(true /* should_be_vm_thread */);
1156 assert(_mutator_alloc_region.get() == NULL ||
1157 !expect_null_mutator_alloc_region,
1158 "the current alloc region was unexpectedly found to be non-NULL");
1159
1160 if (!isHumongous(word_size)) {
1161 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1162 false /* bot_updates */);
1163 } else {
1164 HeapWord* result = humongous_obj_allocate(word_size);
1165 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1166 g1_policy()->set_initiate_conc_mark_if_possible();
1167 }
1168 return result;
1169 }
1170
1171 ShouldNotReachHere();
1172 }
1173
1174 class PostMCRemSetClearClosure: public HeapRegionClosure {
1175 G1CollectedHeap* _g1h;
1176 ModRefBarrierSet* _mr_bs;
1177 public:
1178 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1179 _g1h(g1h), _mr_bs(mr_bs) { }
1180 bool doHeapRegion(HeapRegion* r) {
1181 if (r->continuesHumongous()) {
1182 return false;
1183 }
1184 _g1h->reset_gc_time_stamps(r);
1185 HeapRegionRemSet* hrrs = r->rem_set();
1186 if (hrrs != NULL) hrrs->clear();
1187 // You might think here that we could clear just the cards
1188 // corresponding to the used region. But no: if we leave a dirty card
1189 // in a region we might allocate into, then it would prevent that card
1190 // from being enqueued, and cause it to be missed.
1191 // Re: the performance cost: we shouldn't be doing full GC anyway!
1192 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1193 return false;
1194 }
1195 };
1196
1197 void G1CollectedHeap::clear_rsets_post_compaction() {
1198 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1199 heap_region_iterate(&rs_clear);
1200 }
1201
1202 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1203 G1CollectedHeap* _g1h;
1204 UpdateRSOopClosure _cl;
1205 int _worker_i;
1206 public:
1207 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1208 _cl(g1->g1_rem_set(), worker_i),
1209 _worker_i(worker_i),
1210 _g1h(g1)
1211 { }
1212
1213 bool doHeapRegion(HeapRegion* r) {
1214 if (!r->continuesHumongous()) {
1215 _cl.set_from(r);
1216 r->oop_iterate(&_cl);
1217 }
1218 return false;
1219 }
1220 };
1221
1222 class ParRebuildRSTask: public AbstractGangTask {
1223 G1CollectedHeap* _g1;
1224 public:
1225 ParRebuildRSTask(G1CollectedHeap* g1)
1226 : AbstractGangTask("ParRebuildRSTask"),
1227 _g1(g1)
1228 { }
1229
1230 void work(uint worker_id) {
1231 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1232 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1233 _g1->workers()->active_workers(),
1234 HeapRegion::RebuildRSClaimValue);
1235 }
1236 };
1237
1238 class PostCompactionPrinterClosure: public HeapRegionClosure {
1239 private:
1240 G1HRPrinter* _hr_printer;
1241 public:
1242 bool doHeapRegion(HeapRegion* hr) {
1243 assert(!hr->is_young(), "not expecting to find young regions");
1244 // We only generate output for non-empty regions.
1245 if (!hr->is_empty()) {
1246 if (!hr->isHumongous()) {
1247 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1248 } else if (hr->startsHumongous()) {
1249 if (hr->region_num() == 1) {
1250 // single humongous region
1251 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1252 } else {
1253 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1254 }
1255 } else {
1256 assert(hr->continuesHumongous(), "only way to get here");
1257 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1258 }
1259 }
1260 return false;
1261 }
1262
1263 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1264 : _hr_printer(hr_printer) { }
1265 };
1266
1267 void G1CollectedHeap::print_hrs_post_compaction() {
1268 PostCompactionPrinterClosure cl(hr_printer());
1269 heap_region_iterate(&cl);
1270 }
1271
1272 double G1CollectedHeap::verify(bool guard, const char* msg) {
1273 double verify_time_ms = 0.0;
1274
1275 if (guard && total_collections() >= VerifyGCStartAt) {
1276 double verify_start = os::elapsedTime();
1277 HandleMark hm; // Discard invalid handles created during verification
1278 prepare_for_verify();
1279 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
1280 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
1281 }
1282
1283 return verify_time_ms;
1284 }
1285
1286 void G1CollectedHeap::verify_before_gc() {
1287 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
1288 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
1289 }
1290
1291 void G1CollectedHeap::verify_after_gc() {
1292 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
1293 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
1294 }
1295
1296 bool G1CollectedHeap::do_collection(bool explicit_gc,
1297 bool clear_all_soft_refs,
1298 size_t word_size) {
1299 assert_at_safepoint(true /* should_be_vm_thread */);
1300
1301 if (GC_locker::check_active_before_gc()) {
1302 return false;
1303 }
1304
1305 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1306 gc_timer->register_gc_start(os::elapsed_counter());
1307
1308 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1309 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1310
1311 SvcGCMarker sgcm(SvcGCMarker::FULL);
1312 ResourceMark rm;
1313
1314 print_heap_before_gc();
1315 trace_heap_before_gc(gc_tracer);
1316
1317 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1318
1319 HRSPhaseSetter x(HRSPhaseFullGC);
1320 verify_region_sets_optional();
1321
1322 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1323 collector_policy()->should_clear_all_soft_refs();
1324
1325 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1326
1327 {
1328 IsGCActiveMark x;
1329
1330 // Timing
1331 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1332 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1333 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1334
1335 {
1336 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1337 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1338 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1339
1340 double start = os::elapsedTime();
1341 g1_policy()->record_full_collection_start();
1342
1343 // Note: When we have a more flexible GC logging framework that
1344 // allows us to add optional attributes to a GC log record we
1345 // could consider timing and reporting how long we wait in the
1346 // following two methods.
1347 wait_while_free_regions_coming();
1348 // If we start the compaction before the CM threads finish
1349 // scanning the root regions we might trip them over as we'll
1350 // be moving objects / updating references. So let's wait until
1351 // they are done. By telling them to abort, they should complete
1352 // early.
1353 _cm->root_regions()->abort();
1354 _cm->root_regions()->wait_until_scan_finished();
1355 append_secondary_free_list_if_not_empty_with_lock();
1356
1357 gc_prologue(true);
1358 increment_total_collections(true /* full gc */);
1359 increment_old_marking_cycles_started();
1360
1361 assert(used() == recalculate_used(), "Should be equal");
1362
1363 verify_before_gc();
1364
1365 pre_full_gc_dump(gc_timer);
1366
1367 COMPILER2_PRESENT(DerivedPointerTable::clear());
1368
1369 // Disable discovery and empty the discovered lists
1370 // for the CM ref processor.
1371 ref_processor_cm()->disable_discovery();
1372 ref_processor_cm()->abandon_partial_discovery();
1373 ref_processor_cm()->verify_no_references_recorded();
1374
1375 // Abandon current iterations of concurrent marking and concurrent
1376 // refinement, if any are in progress. We have to do this before
1377 // wait_until_scan_finished() below.
1378 concurrent_mark()->abort();
1379
1380 // Make sure we'll choose a new allocation region afterwards.
1381 release_mutator_alloc_region();
1382 abandon_gc_alloc_regions();
1383 g1_rem_set()->cleanupHRRS();
1384
1385 // We should call this after we retire any currently active alloc
1386 // regions so that all the ALLOC / RETIRE events are generated
1387 // before the start GC event.
1388 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1389
1390 // We may have added regions to the current incremental collection
1391 // set between the last GC or pause and now. We need to clear the
1392 // incremental collection set and then start rebuilding it afresh
1393 // after this full GC.
1394 abandon_collection_set(g1_policy()->inc_cset_head());
1395 g1_policy()->clear_incremental_cset();
1396 g1_policy()->stop_incremental_cset_building();
1397
1398 tear_down_region_sets(false /* free_list_only */);
1399 g1_policy()->set_gcs_are_young(true);
1400
1401 // See the comments in g1CollectedHeap.hpp and
1402 // G1CollectedHeap::ref_processing_init() about
1403 // how reference processing currently works in G1.
1404
1405 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1406 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1407
1408 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1409 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1410
1411 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1412 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1413
1414 // Do collection work
1415 {
1416 HandleMark hm; // Discard invalid handles created during gc
1417 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1418 }
1419
1420 assert(free_regions() == 0, "we should not have added any free regions");
1421 rebuild_region_sets(false /* free_list_only */);
1422
1423 // Enqueue any discovered reference objects that have
1424 // not been removed from the discovered lists.
1425 ref_processor_stw()->enqueue_discovered_references();
1426
1427 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1428
1429 MemoryService::track_memory_usage();
1430
1431 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1432 ref_processor_stw()->verify_no_references_recorded();
1433
1434 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1435 ClassLoaderDataGraph::purge();
1436 MetaspaceAux::verify_metrics();
1437
1438 // Note: since we've just done a full GC, concurrent
1439 // marking is no longer active. Therefore we need not
1440 // re-enable reference discovery for the CM ref processor.
1441 // That will be done at the start of the next marking cycle.
1442 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1443 ref_processor_cm()->verify_no_references_recorded();
1444
1445 reset_gc_time_stamp();
1446 // Since everything potentially moved, we will clear all remembered
1447 // sets, and clear all cards. Later we will rebuild remembered
1448 // sets. We will also reset the GC time stamps of the regions.
1449 clear_rsets_post_compaction();
1450 check_gc_time_stamps();
1451
1452 // Resize the heap if necessary.
1453 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1454
1455 if (_hr_printer.is_active()) {
1456 // We should do this after we potentially resize the heap so
1457 // that all the COMMIT / UNCOMMIT events are generated before
1458 // the end GC event.
1459
1460 print_hrs_post_compaction();
1461 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1462 }
1463
1464 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1465 if (hot_card_cache->use_cache()) {
1466 hot_card_cache->reset_card_counts();
1467 hot_card_cache->reset_hot_cache();
1468 }
1469
1470 // Rebuild remembered sets of all regions.
1471 if (G1CollectedHeap::use_parallel_gc_threads()) {
1472 uint n_workers =
1473 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1474 workers()->active_workers(),
1475 Threads::number_of_non_daemon_threads());
1476 assert(UseDynamicNumberOfGCThreads ||
1477 n_workers == workers()->total_workers(),
1478 "If not dynamic should be using all the workers");
1479 workers()->set_active_workers(n_workers);
1480 // Set parallel threads in the heap (_n_par_threads) only
1481 // before a parallel phase and always reset it to 0 after
1482 // the phase so that the number of parallel threads does
1483 // no get carried forward to a serial phase where there
1484 // may be code that is "possibly_parallel".
1485 set_par_threads(n_workers);
1486
1487 ParRebuildRSTask rebuild_rs_task(this);
1488 assert(check_heap_region_claim_values(
1489 HeapRegion::InitialClaimValue), "sanity check");
1490 assert(UseDynamicNumberOfGCThreads ||
1491 workers()->active_workers() == workers()->total_workers(),
1492 "Unless dynamic should use total workers");
1493 // Use the most recent number of active workers
1494 assert(workers()->active_workers() > 0,
1495 "Active workers not properly set");
1496 set_par_threads(workers()->active_workers());
1497 workers()->run_task(&rebuild_rs_task);
1498 set_par_threads(0);
1499 assert(check_heap_region_claim_values(
1500 HeapRegion::RebuildRSClaimValue), "sanity check");
1501 reset_heap_region_claim_values();
1502 } else {
1503 RebuildRSOutOfRegionClosure rebuild_rs(this);
1504 heap_region_iterate(&rebuild_rs);
1505 }
1506
1507 if (true) { // FIXME
1508 MetaspaceGC::compute_new_size();
1509 }
1510
1511 #ifdef TRACESPINNING
1512 ParallelTaskTerminator::print_termination_counts();
1513 #endif
1514
1515 // Discard all rset updates
1516 JavaThread::dirty_card_queue_set().abandon_logs();
1517 assert(!G1DeferredRSUpdate
1518 || (G1DeferredRSUpdate &&
1519 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1520
1521 _young_list->reset_sampled_info();
1522 // At this point there should be no regions in the
1523 // entire heap tagged as young.
1524 assert(check_young_list_empty(true /* check_heap */),
1525 "young list should be empty at this point");
1526
1527 // Update the number of full collections that have been completed.
1528 increment_old_marking_cycles_completed(false /* concurrent */);
1529
1530 _hrs.verify_optional();
1531 verify_region_sets_optional();
1532
1533 verify_after_gc();
1534
1535 // Start a new incremental collection set for the next pause
1536 assert(g1_policy()->collection_set() == NULL, "must be");
1537 g1_policy()->start_incremental_cset_building();
1538
1539 // Clear the _cset_fast_test bitmap in anticipation of adding
1540 // regions to the incremental collection set for the next
1541 // evacuation pause.
1542 clear_cset_fast_test();
1543
1544 init_mutator_alloc_region();
1545
1546 double end = os::elapsedTime();
1547 g1_policy()->record_full_collection_end();
1548
1549 if (G1Log::fine()) {
1550 g1_policy()->print_heap_transition();
1551 }
1552
1553 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1554 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1555 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1556 // before any GC notifications are raised.
1557 g1mm()->update_sizes();
1558
1559 gc_epilogue(true);
1560 }
1561
1562 if (G1Log::finer()) {
1563 g1_policy()->print_detailed_heap_transition(true /* full */);
1564 }
1565
1566 print_heap_after_gc();
1567 trace_heap_after_gc(gc_tracer);
1568
1569 post_full_gc_dump(gc_timer);
1570
1571 gc_timer->register_gc_end(os::elapsed_counter());
1572 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1573 }
1574
1575 return true;
1576 }
1577
1578 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1579 // do_collection() will return whether it succeeded in performing
1580 // the GC. Currently, there is no facility on the
1581 // do_full_collection() API to notify the caller than the collection
1582 // did not succeed (e.g., because it was locked out by the GC
1583 // locker). So, right now, we'll ignore the return value.
1584 bool dummy = do_collection(true, /* explicit_gc */
1585 clear_all_soft_refs,
1586 0 /* word_size */);
1587 }
1588
1589 // This code is mostly copied from TenuredGeneration.
1590 void
1591 G1CollectedHeap::
1592 resize_if_necessary_after_full_collection(size_t word_size) {
1593 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1594
1595 // Include the current allocation, if any, and bytes that will be
1596 // pre-allocated to support collections, as "used".
1597 const size_t used_after_gc = used();
1598 const size_t capacity_after_gc = capacity();
1599 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1600
1601 // This is enforced in arguments.cpp.
1602 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1603 "otherwise the code below doesn't make sense");
1604
1605 // We don't have floating point command-line arguments
1606 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1607 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1608 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1609 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1610
1611 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1612 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1613
1614 // We have to be careful here as these two calculations can overflow
1615 // 32-bit size_t's.
1616 double used_after_gc_d = (double) used_after_gc;
1617 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1618 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1619
1620 // Let's make sure that they are both under the max heap size, which
1621 // by default will make them fit into a size_t.
1622 double desired_capacity_upper_bound = (double) max_heap_size;
1623 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1624 desired_capacity_upper_bound);
1625 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1626 desired_capacity_upper_bound);
1627
1628 // We can now safely turn them into size_t's.
1629 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1630 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1631
1632 // This assert only makes sense here, before we adjust them
1633 // with respect to the min and max heap size.
1634 assert(minimum_desired_capacity <= maximum_desired_capacity,
1635 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1636 "maximum_desired_capacity = "SIZE_FORMAT,
1637 minimum_desired_capacity, maximum_desired_capacity));
1638
1639 // Should not be greater than the heap max size. No need to adjust
1640 // it with respect to the heap min size as it's a lower bound (i.e.,
1641 // we'll try to make the capacity larger than it, not smaller).
1642 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1643 // Should not be less than the heap min size. No need to adjust it
1644 // with respect to the heap max size as it's an upper bound (i.e.,
1645 // we'll try to make the capacity smaller than it, not greater).
1646 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1647
1648 if (capacity_after_gc < minimum_desired_capacity) {
1649 // Don't expand unless it's significant
1650 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1651 ergo_verbose4(ErgoHeapSizing,
1652 "attempt heap expansion",
1653 ergo_format_reason("capacity lower than "
1654 "min desired capacity after Full GC")
1655 ergo_format_byte("capacity")
1656 ergo_format_byte("occupancy")
1657 ergo_format_byte_perc("min desired capacity"),
1658 capacity_after_gc, used_after_gc,
1659 minimum_desired_capacity, (double) MinHeapFreeRatio);
1660 expand(expand_bytes);
1661
1662 // No expansion, now see if we want to shrink
1663 } else if (capacity_after_gc > maximum_desired_capacity) {
1664 // Capacity too large, compute shrinking size
1665 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1666 ergo_verbose4(ErgoHeapSizing,
1667 "attempt heap shrinking",
1668 ergo_format_reason("capacity higher than "
1669 "max desired capacity after Full GC")
1670 ergo_format_byte("capacity")
1671 ergo_format_byte("occupancy")
1672 ergo_format_byte_perc("max desired capacity"),
1673 capacity_after_gc, used_after_gc,
1674 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1675 shrink(shrink_bytes);
1676 }
1677 }
1678
1679
1680 HeapWord*
1681 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1682 bool* succeeded) {
1683 assert_at_safepoint(true /* should_be_vm_thread */);
1684
1685 *succeeded = true;
1686 // Let's attempt the allocation first.
1687 HeapWord* result =
1688 attempt_allocation_at_safepoint(word_size,
1689 false /* expect_null_mutator_alloc_region */);
1690 if (result != NULL) {
1691 assert(*succeeded, "sanity");
1692 return result;
1693 }
1694
1695 // In a G1 heap, we're supposed to keep allocation from failing by
1696 // incremental pauses. Therefore, at least for now, we'll favor
1697 // expansion over collection. (This might change in the future if we can
1698 // do something smarter than full collection to satisfy a failed alloc.)
1699 result = expand_and_allocate(word_size);
1700 if (result != NULL) {
1701 assert(*succeeded, "sanity");
1702 return result;
1703 }
1704
1705 // Expansion didn't work, we'll try to do a Full GC.
1706 bool gc_succeeded = do_collection(false, /* explicit_gc */
1707 false, /* clear_all_soft_refs */
1708 word_size);
1709 if (!gc_succeeded) {
1710 *succeeded = false;
1711 return NULL;
1712 }
1713
1714 // Retry the allocation
1715 result = attempt_allocation_at_safepoint(word_size,
1716 true /* expect_null_mutator_alloc_region */);
1717 if (result != NULL) {
1718 assert(*succeeded, "sanity");
1719 return result;
1720 }
1721
1722 // Then, try a Full GC that will collect all soft references.
1723 gc_succeeded = do_collection(false, /* explicit_gc */
1724 true, /* clear_all_soft_refs */
1725 word_size);
1726 if (!gc_succeeded) {
1727 *succeeded = false;
1728 return NULL;
1729 }
1730
1731 // Retry the allocation once more
1732 result = attempt_allocation_at_safepoint(word_size,
1733 true /* expect_null_mutator_alloc_region */);
1734 if (result != NULL) {
1735 assert(*succeeded, "sanity");
1736 return result;
1737 }
1738
1739 assert(!collector_policy()->should_clear_all_soft_refs(),
1740 "Flag should have been handled and cleared prior to this point");
1741
1742 // What else? We might try synchronous finalization later. If the total
1743 // space available is large enough for the allocation, then a more
1744 // complete compaction phase than we've tried so far might be
1745 // appropriate.
1746 assert(*succeeded, "sanity");
1747 return NULL;
1748 }
1749
1750 // Attempting to expand the heap sufficiently
1751 // to support an allocation of the given "word_size". If
1752 // successful, perform the allocation and return the address of the
1753 // allocated block, or else "NULL".
1754
1755 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1756 assert_at_safepoint(true /* should_be_vm_thread */);
1757
1758 verify_region_sets_optional();
1759
1760 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1761 ergo_verbose1(ErgoHeapSizing,
1762 "attempt heap expansion",
1763 ergo_format_reason("allocation request failed")
1764 ergo_format_byte("allocation request"),
1765 word_size * HeapWordSize);
1766 if (expand(expand_bytes)) {
1767 _hrs.verify_optional();
1768 verify_region_sets_optional();
1769 return attempt_allocation_at_safepoint(word_size,
1770 false /* expect_null_mutator_alloc_region */);
1771 }
1772 return NULL;
1773 }
1774
1775 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1776 HeapWord* new_end) {
1777 assert(old_end != new_end, "don't call this otherwise");
1778 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1779
1780 // Update the committed mem region.
1781 _g1_committed.set_end(new_end);
1782 // Tell the card table about the update.
1783 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1784 // Tell the BOT about the update.
1785 _bot_shared->resize(_g1_committed.word_size());
1786 // Tell the hot card cache about the update
1787 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1788 }
1789
1790 bool G1CollectedHeap::expand(size_t expand_bytes) {
1791 size_t old_mem_size = _g1_storage.committed_size();
1792 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1793 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1794 HeapRegion::GrainBytes);
1795 ergo_verbose2(ErgoHeapSizing,
1796 "expand the heap",
1797 ergo_format_byte("requested expansion amount")
1798 ergo_format_byte("attempted expansion amount"),
1799 expand_bytes, aligned_expand_bytes);
1800
1801 // First commit the memory.
1802 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1803 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1804 if (successful) {
1805 // Then propagate this update to the necessary data structures.
1806 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1807 update_committed_space(old_end, new_end);
1808
1809 FreeRegionList expansion_list("Local Expansion List");
1810 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1811 assert(mr.start() == old_end, "post-condition");
1812 // mr might be a smaller region than what was requested if
1813 // expand_by() was unable to allocate the HeapRegion instances
1814 assert(mr.end() <= new_end, "post-condition");
1815
1816 size_t actual_expand_bytes = mr.byte_size();
1817 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1818 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1819 "post-condition");
1820 if (actual_expand_bytes < aligned_expand_bytes) {
1821 // We could not expand _hrs to the desired size. In this case we
1822 // need to shrink the committed space accordingly.
1823 assert(mr.end() < new_end, "invariant");
1824
1825 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1826 // First uncommit the memory.
1827 _g1_storage.shrink_by(diff_bytes);
1828 // Then propagate this update to the necessary data structures.
1829 update_committed_space(new_end, mr.end());
1830 }
1831 _free_list.add_as_tail(&expansion_list);
1832
1833 if (_hr_printer.is_active()) {
1834 HeapWord* curr = mr.start();
1835 while (curr < mr.end()) {
1836 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1837 _hr_printer.commit(curr, curr_end);
1838 curr = curr_end;
1839 }
1840 assert(curr == mr.end(), "post-condition");
1841 }
1842 g1_policy()->record_new_heap_size(n_regions());
1843 } else {
1844 ergo_verbose0(ErgoHeapSizing,
1845 "did not expand the heap",
1846 ergo_format_reason("heap expansion operation failed"));
1847 // The expansion of the virtual storage space was unsuccessful.
1848 // Let's see if it was because we ran out of swap.
1849 if (G1ExitOnExpansionFailure &&
1850 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1851 // We had head room...
1852 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1853 }
1854 }
1855 return successful;
1856 }
1857
1858 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1859 size_t old_mem_size = _g1_storage.committed_size();
1860 size_t aligned_shrink_bytes =
1861 ReservedSpace::page_align_size_down(shrink_bytes);
1862 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1863 HeapRegion::GrainBytes);
1864 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1865
1866 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1867 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1868 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1869
1870 ergo_verbose3(ErgoHeapSizing,
1871 "shrink the heap",
1872 ergo_format_byte("requested shrinking amount")
1873 ergo_format_byte("aligned shrinking amount")
1874 ergo_format_byte("attempted shrinking amount"),
1875 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1876 if (num_regions_removed > 0) {
1877 _g1_storage.shrink_by(shrunk_bytes);
1878 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1879
1880 if (_hr_printer.is_active()) {
1881 HeapWord* curr = old_end;
1882 while (curr > new_end) {
1883 HeapWord* curr_end = curr;
1884 curr -= HeapRegion::GrainWords;
1885 _hr_printer.uncommit(curr, curr_end);
1886 }
1887 }
1888
1889 _expansion_regions += num_regions_removed;
1890 update_committed_space(old_end, new_end);
1891 HeapRegionRemSet::shrink_heap(n_regions());
1892 g1_policy()->record_new_heap_size(n_regions());
1893 } else {
1894 ergo_verbose0(ErgoHeapSizing,
1895 "did not shrink the heap",
1896 ergo_format_reason("heap shrinking operation failed"));
1897 }
1898 }
1899
1900 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1901 verify_region_sets_optional();
1902
1903 // We should only reach here at the end of a Full GC which means we
1904 // should not not be holding to any GC alloc regions. The method
1905 // below will make sure of that and do any remaining clean up.
1906 abandon_gc_alloc_regions();
1907
1908 // Instead of tearing down / rebuilding the free lists here, we
1909 // could instead use the remove_all_pending() method on free_list to
1910 // remove only the ones that we need to remove.
1911 tear_down_region_sets(true /* free_list_only */);
1912 shrink_helper(shrink_bytes);
1913 rebuild_region_sets(true /* free_list_only */);
1914
1915 _hrs.verify_optional();
1916 verify_region_sets_optional();
1917 }
1918
1919 // Public methods.
1920
1921 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1922 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1923 #endif // _MSC_VER
1924
1925
1926 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1927 SharedHeap(policy_),
1928 _g1_policy(policy_),
1929 _dirty_card_queue_set(false),
1930 _into_cset_dirty_card_queue_set(false),
1931 _is_alive_closure_cm(this),
1932 _is_alive_closure_stw(this),
1933 _ref_processor_cm(NULL),
1934 _ref_processor_stw(NULL),
1935 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1936 _bot_shared(NULL),
1937 _evac_failure_scan_stack(NULL),
1938 _mark_in_progress(false),
1939 _cg1r(NULL), _summary_bytes_used(0),
1940 _g1mm(NULL),
1941 _refine_cte_cl(NULL),
1942 _full_collection(false),
1943 _free_list("Master Free List"),
1944 _secondary_free_list("Secondary Free List"),
1945 _old_set("Old Set"),
1946 _humongous_set("Master Humongous Set"),
1947 _free_regions_coming(false),
1948 _young_list(new YoungList(this)),
1949 _gc_time_stamp(0),
1950 _retained_old_gc_alloc_region(NULL),
1951 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1952 _old_plab_stats(OldPLABSize, PLABWeight),
1953 _expand_heap_after_alloc_failure(true),
1954 _surviving_young_words(NULL),
1955 _old_marking_cycles_started(0),
1956 _old_marking_cycles_completed(0),
1957 _concurrent_cycle_started(false),
1958 _in_cset_fast_test(NULL),
1959 _in_cset_fast_test_base(NULL),
1960 _dirty_cards_region_list(NULL),
1961 _worker_cset_start_region(NULL),
1962 _worker_cset_start_region_time_stamp(NULL),
1963 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1964 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1965 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1966 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1967
1968 _g1h = this;
1969 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1970 vm_exit_during_initialization("Failed necessary allocation.");
1971 }
1972
1973 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1974
1975 int n_queues = MAX2((int)ParallelGCThreads, 1);
1976 _task_queues = new RefToScanQueueSet(n_queues);
1977
1978 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1979 assert(n_rem_sets > 0, "Invariant.");
1980
1981 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1982 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1983 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1984
1985 for (int i = 0; i < n_queues; i++) {
1986 RefToScanQueue* q = new RefToScanQueue();
1987 q->initialize();
1988 _task_queues->register_queue(i, q);
1989 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1990 }
1991 clear_cset_start_regions();
1992
1993 // Initialize the G1EvacuationFailureALot counters and flags.
1994 NOT_PRODUCT(reset_evacuation_should_fail();)
1995
1996 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1997 }
1998
1999 jint G1CollectedHeap::initialize() {
2000 CollectedHeap::pre_initialize();
2001 os::enable_vtime();
2002
2003 G1Log::init();
2004
2005 // Necessary to satisfy locking discipline assertions.
2006
2007 MutexLocker x(Heap_lock);
2008
2009 // We have to initialize the printer before committing the heap, as
2010 // it will be used then.
2011 _hr_printer.set_active(G1PrintHeapRegions);
2012
2013 // While there are no constraints in the GC code that HeapWordSize
2014 // be any particular value, there are multiple other areas in the
2015 // system which believe this to be true (e.g. oop->object_size in some
2016 // cases incorrectly returns the size in wordSize units rather than
2017 // HeapWordSize).
2018 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2019
2020 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2021 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2022 size_t heap_alignment = collector_policy()->max_alignment();
2023
2024 // Ensure that the sizes are properly aligned.
2025 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2026 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2027 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2028
2029 _cg1r = new ConcurrentG1Refine(this);
2030
2031 // Reserve the maximum.
2032
2033 // When compressed oops are enabled, the preferred heap base
2034 // is calculated by subtracting the requested size from the
2035 // 32Gb boundary and using the result as the base address for
2036 // heap reservation. If the requested size is not aligned to
2037 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2038 // into the ReservedHeapSpace constructor) then the actual
2039 // base of the reserved heap may end up differing from the
2040 // address that was requested (i.e. the preferred heap base).
2041 // If this happens then we could end up using a non-optimal
2042 // compressed oops mode.
2043
2044 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2045 heap_alignment);
2046
2047 // It is important to do this in a way such that concurrent readers can't
2048 // temporarily think something is in the heap. (I've actually seen this
2049 // happen in asserts: DLD.)
2050 _reserved.set_word_size(0);
2051 _reserved.set_start((HeapWord*)heap_rs.base());
2052 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2053
2054 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2055
2056 // Create the gen rem set (and barrier set) for the entire reserved region.
2057 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2058 set_barrier_set(rem_set()->bs());
2059 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2060 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2061 } else {
2062 vm_exit_during_initialization("G1 requires a mod ref bs.");
2063 return JNI_ENOMEM;
2064 }
2065
2066 // Also create a G1 rem set.
2067 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2068 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2069 } else {
2070 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2071 return JNI_ENOMEM;
2072 }
2073
2074 // Carve out the G1 part of the heap.
2075
2076 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2077 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2078 g1_rs.size()/HeapWordSize);
2079
2080 _g1_storage.initialize(g1_rs, 0);
2081 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2082 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2083 (HeapWord*) _g1_reserved.end(),
2084 _expansion_regions);
2085
2086 // Do later initialization work for concurrent refinement.
2087 _cg1r->init();
2088
2089 // 6843694 - ensure that the maximum region index can fit
2090 // in the remembered set structures.
2091 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2092 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2093
2094 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2095 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2096 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2097 "too many cards per region");
2098
2099 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2100
2101 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2102 heap_word_size(init_byte_size));
2103
2104 _g1h = this;
2105
2106 _in_cset_fast_test_length = max_regions();
2107 _in_cset_fast_test_base =
2108 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2109
2110 // We're biasing _in_cset_fast_test to avoid subtracting the
2111 // beginning of the heap every time we want to index; basically
2112 // it's the same with what we do with the card table.
2113 _in_cset_fast_test = _in_cset_fast_test_base -
2114 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2115
2116 // Clear the _cset_fast_test bitmap in anticipation of adding
2117 // regions to the incremental collection set for the first
2118 // evacuation pause.
2119 clear_cset_fast_test();
2120
2121 // Create the ConcurrentMark data structure and thread.
2122 // (Must do this late, so that "max_regions" is defined.)
2123 _cm = new ConcurrentMark(this, heap_rs);
2124 if (_cm == NULL || !_cm->completed_initialization()) {
2125 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2126 return JNI_ENOMEM;
2127 }
2128 _cmThread = _cm->cmThread();
2129
2130 // Initialize the from_card cache structure of HeapRegionRemSet.
2131 HeapRegionRemSet::init_heap(max_regions());
2132
2133 // Now expand into the initial heap size.
2134 if (!expand(init_byte_size)) {
2135 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2136 return JNI_ENOMEM;
2137 }
2138
2139 // Perform any initialization actions delegated to the policy.
2140 g1_policy()->init();
2141
2142 _refine_cte_cl =
2143 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2144 g1_rem_set(),
2145 concurrent_g1_refine());
2146 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2147
2148 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2149 SATB_Q_FL_lock,
2150 G1SATBProcessCompletedThreshold,
2151 Shared_SATB_Q_lock);
2152
2153 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2154 DirtyCardQ_FL_lock,
2155 concurrent_g1_refine()->yellow_zone(),
2156 concurrent_g1_refine()->red_zone(),
2157 Shared_DirtyCardQ_lock);
2158
2159 if (G1DeferredRSUpdate) {
2160 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2161 DirtyCardQ_FL_lock,
2162 -1, // never trigger processing
2163 -1, // no limit on length
2164 Shared_DirtyCardQ_lock,
2165 &JavaThread::dirty_card_queue_set());
2166 }
2167
2168 // Initialize the card queue set used to hold cards containing
2169 // references into the collection set.
2170 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2171 DirtyCardQ_FL_lock,
2172 -1, // never trigger processing
2173 -1, // no limit on length
2174 Shared_DirtyCardQ_lock,
2175 &JavaThread::dirty_card_queue_set());
2176
2177 // In case we're keeping closure specialization stats, initialize those
2178 // counts and that mechanism.
2179 SpecializationStats::clear();
2180
2181 // Here we allocate the dummy full region that is required by the
2182 // G1AllocRegion class. If we don't pass an address in the reserved
2183 // space here, lots of asserts fire.
2184
2185 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2186 _g1_reserved.start());
2187 // We'll re-use the same region whether the alloc region will
2188 // require BOT updates or not and, if it doesn't, then a non-young
2189 // region will complain that it cannot support allocations without
2190 // BOT updates. So we'll tag the dummy region as young to avoid that.
2191 dummy_region->set_young();
2192 // Make sure it's full.
2193 dummy_region->set_top(dummy_region->end());
2194 G1AllocRegion::setup(this, dummy_region);
2195
2196 init_mutator_alloc_region();
2197
2198 // Do create of the monitoring and management support so that
2199 // values in the heap have been properly initialized.
2200 _g1mm = new G1MonitoringSupport(this);
2201
2202 return JNI_OK;
2203 }
2204
2205 void G1CollectedHeap::ref_processing_init() {
2206 // Reference processing in G1 currently works as follows:
2207 //
2208 // * There are two reference processor instances. One is
2209 // used to record and process discovered references
2210 // during concurrent marking; the other is used to
2211 // record and process references during STW pauses
2212 // (both full and incremental).
2213 // * Both ref processors need to 'span' the entire heap as
2214 // the regions in the collection set may be dotted around.
2215 //
2216 // * For the concurrent marking ref processor:
2217 // * Reference discovery is enabled at initial marking.
2218 // * Reference discovery is disabled and the discovered
2219 // references processed etc during remarking.
2220 // * Reference discovery is MT (see below).
2221 // * Reference discovery requires a barrier (see below).
2222 // * Reference processing may or may not be MT
2223 // (depending on the value of ParallelRefProcEnabled
2224 // and ParallelGCThreads).
2225 // * A full GC disables reference discovery by the CM
2226 // ref processor and abandons any entries on it's
2227 // discovered lists.
2228 //
2229 // * For the STW processor:
2230 // * Non MT discovery is enabled at the start of a full GC.
2231 // * Processing and enqueueing during a full GC is non-MT.
2232 // * During a full GC, references are processed after marking.
2233 //
2234 // * Discovery (may or may not be MT) is enabled at the start
2235 // of an incremental evacuation pause.
2236 // * References are processed near the end of a STW evacuation pause.
2237 // * For both types of GC:
2238 // * Discovery is atomic - i.e. not concurrent.
2239 // * Reference discovery will not need a barrier.
2240
2241 SharedHeap::ref_processing_init();
2242 MemRegion mr = reserved_region();
2243
2244 // Concurrent Mark ref processor
2245 _ref_processor_cm =
2246 new ReferenceProcessor(mr, // span
2247 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2248 // mt processing
2249 (int) ParallelGCThreads,
2250 // degree of mt processing
2251 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2252 // mt discovery
2253 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2254 // degree of mt discovery
2255 false,
2256 // Reference discovery is not atomic
2257 &_is_alive_closure_cm,
2258 // is alive closure
2259 // (for efficiency/performance)
2260 true);
2261 // Setting next fields of discovered
2262 // lists requires a barrier.
2263
2264 // STW ref processor
2265 _ref_processor_stw =
2266 new ReferenceProcessor(mr, // span
2267 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2268 // mt processing
2269 MAX2((int)ParallelGCThreads, 1),
2270 // degree of mt processing
2271 (ParallelGCThreads > 1),
2272 // mt discovery
2273 MAX2((int)ParallelGCThreads, 1),
2274 // degree of mt discovery
2275 true,
2276 // Reference discovery is atomic
2277 &_is_alive_closure_stw,
2278 // is alive closure
2279 // (for efficiency/performance)
2280 false);
2281 // Setting next fields of discovered
2282 // lists requires a barrier.
2283 }
2284
2285 size_t G1CollectedHeap::capacity() const {
2286 return _g1_committed.byte_size();
2287 }
2288
2289 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2290 assert(!hr->continuesHumongous(), "pre-condition");
2291 hr->reset_gc_time_stamp();
2292 if (hr->startsHumongous()) {
2293 uint first_index = hr->hrs_index() + 1;
2294 uint last_index = hr->last_hc_index();
2295 for (uint i = first_index; i < last_index; i += 1) {
2296 HeapRegion* chr = region_at(i);
2297 assert(chr->continuesHumongous(), "sanity");
2298 chr->reset_gc_time_stamp();
2299 }
2300 }
2301 }
2302
2303 #ifndef PRODUCT
2304 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2305 private:
2306 unsigned _gc_time_stamp;
2307 bool _failures;
2308
2309 public:
2310 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2311 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2312
2313 virtual bool doHeapRegion(HeapRegion* hr) {
2314 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2315 if (_gc_time_stamp != region_gc_time_stamp) {
2316 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2317 "expected %d", HR_FORMAT_PARAMS(hr),
2318 region_gc_time_stamp, _gc_time_stamp);
2319 _failures = true;
2320 }
2321 return false;
2322 }
2323
2324 bool failures() { return _failures; }
2325 };
2326
2327 void G1CollectedHeap::check_gc_time_stamps() {
2328 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2329 heap_region_iterate(&cl);
2330 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2331 }
2332 #endif // PRODUCT
2333
2334 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2335 DirtyCardQueue* into_cset_dcq,
2336 bool concurrent,
2337 int worker_i) {
2338 // Clean cards in the hot card cache
2339 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2340 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2341
2342 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2343 int n_completed_buffers = 0;
2344 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2345 n_completed_buffers++;
2346 }
2347 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2348 dcqs.clear_n_completed_buffers();
2349 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2350 }
2351
2352
2353 // Computes the sum of the storage used by the various regions.
2354
2355 size_t G1CollectedHeap::used() const {
2356 assert(Heap_lock->owner() != NULL,
2357 "Should be owned on this thread's behalf.");
2358 size_t result = _summary_bytes_used;
2359 // Read only once in case it is set to NULL concurrently
2360 HeapRegion* hr = _mutator_alloc_region.get();
2361 if (hr != NULL)
2362 result += hr->used();
2363 return result;
2364 }
2365
2366 size_t G1CollectedHeap::used_unlocked() const {
2367 size_t result = _summary_bytes_used;
2368 return result;
2369 }
2370
2371 class SumUsedClosure: public HeapRegionClosure {
2372 size_t _used;
2373 public:
2374 SumUsedClosure() : _used(0) {}
2375 bool doHeapRegion(HeapRegion* r) {
2376 if (!r->continuesHumongous()) {
2377 _used += r->used();
2378 }
2379 return false;
2380 }
2381 size_t result() { return _used; }
2382 };
2383
2384 size_t G1CollectedHeap::recalculate_used() const {
2385 SumUsedClosure blk;
2386 heap_region_iterate(&blk);
2387 return blk.result();
2388 }
2389
2390 size_t G1CollectedHeap::unsafe_max_alloc() {
2391 if (free_regions() > 0) return HeapRegion::GrainBytes;
2392 // otherwise, is there space in the current allocation region?
2393
2394 // We need to store the current allocation region in a local variable
2395 // here. The problem is that this method doesn't take any locks and
2396 // there may be other threads which overwrite the current allocation
2397 // region field. attempt_allocation(), for example, sets it to NULL
2398 // and this can happen *after* the NULL check here but before the call
2399 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2400 // to be a problem in the optimized build, since the two loads of the
2401 // current allocation region field are optimized away.
2402 HeapRegion* hr = _mutator_alloc_region.get();
2403 if (hr == NULL) {
2404 return 0;
2405 }
2406 return hr->free();
2407 }
2408
2409 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2410 switch (cause) {
2411 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2412 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2413 case GCCause::_g1_humongous_allocation: return true;
2414 default: return false;
2415 }
2416 }
2417
2418 #ifndef PRODUCT
2419 void G1CollectedHeap::allocate_dummy_regions() {
2420 // Let's fill up most of the region
2421 size_t word_size = HeapRegion::GrainWords - 1024;
2422 // And as a result the region we'll allocate will be humongous.
2423 guarantee(isHumongous(word_size), "sanity");
2424
2425 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2426 // Let's use the existing mechanism for the allocation
2427 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2428 if (dummy_obj != NULL) {
2429 MemRegion mr(dummy_obj, word_size);
2430 CollectedHeap::fill_with_object(mr);
2431 } else {
2432 // If we can't allocate once, we probably cannot allocate
2433 // again. Let's get out of the loop.
2434 break;
2435 }
2436 }
2437 }
2438 #endif // !PRODUCT
2439
2440 void G1CollectedHeap::increment_old_marking_cycles_started() {
2441 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2442 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2443 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2444 _old_marking_cycles_started, _old_marking_cycles_completed));
2445
2446 _old_marking_cycles_started++;
2447 }
2448
2449 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2450 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2451
2452 // We assume that if concurrent == true, then the caller is a
2453 // concurrent thread that was joined the Suspendible Thread
2454 // Set. If there's ever a cheap way to check this, we should add an
2455 // assert here.
2456
2457 // Given that this method is called at the end of a Full GC or of a
2458 // concurrent cycle, and those can be nested (i.e., a Full GC can
2459 // interrupt a concurrent cycle), the number of full collections
2460 // completed should be either one (in the case where there was no
2461 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2462 // behind the number of full collections started.
2463
2464 // This is the case for the inner caller, i.e. a Full GC.
2465 assert(concurrent ||
2466 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2467 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2468 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2469 "is inconsistent with _old_marking_cycles_completed = %u",
2470 _old_marking_cycles_started, _old_marking_cycles_completed));
2471
2472 // This is the case for the outer caller, i.e. the concurrent cycle.
2473 assert(!concurrent ||
2474 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2475 err_msg("for outer caller (concurrent cycle): "
2476 "_old_marking_cycles_started = %u "
2477 "is inconsistent with _old_marking_cycles_completed = %u",
2478 _old_marking_cycles_started, _old_marking_cycles_completed));
2479
2480 _old_marking_cycles_completed += 1;
2481
2482 // We need to clear the "in_progress" flag in the CM thread before
2483 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2484 // is set) so that if a waiter requests another System.gc() it doesn't
2485 // incorrectly see that a marking cycle is still in progress.
2486 if (concurrent) {
2487 _cmThread->clear_in_progress();
2488 }
2489
2490 // This notify_all() will ensure that a thread that called
2491 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2492 // and it's waiting for a full GC to finish will be woken up. It is
2493 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2494 FullGCCount_lock->notify_all();
2495 }
2496
2497 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2498 _concurrent_cycle_started = true;
2499 _gc_timer_cm->register_gc_start(start_time);
2500
2501 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2502 trace_heap_before_gc(_gc_tracer_cm);
2503 }
2504
2505 void G1CollectedHeap::register_concurrent_cycle_end() {
2506 if (_concurrent_cycle_started) {
2507 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2508
2509 if (_cm->has_aborted()) {
2510 _gc_tracer_cm->report_concurrent_mode_failure();
2511 }
2512 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2513
2514 _concurrent_cycle_started = false;
2515 }
2516 }
2517
2518 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2519 if (_concurrent_cycle_started) {
2520 trace_heap_after_gc(_gc_tracer_cm);
2521 }
2522 }
2523
2524 G1YCType G1CollectedHeap::yc_type() {
2525 bool is_young = g1_policy()->gcs_are_young();
2526 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2527 bool is_during_mark = mark_in_progress();
2528
2529 if (is_initial_mark) {
2530 return InitialMark;
2531 } else if (is_during_mark) {
2532 return DuringMark;
2533 } else if (is_young) {
2534 return Normal;
2535 } else {
2536 return Mixed;
2537 }
2538 }
2539
2540 void G1CollectedHeap::collect(GCCause::Cause cause) {
2541 assert_heap_not_locked();
2542
2543 unsigned int gc_count_before;
2544 unsigned int old_marking_count_before;
2545 bool retry_gc;
2546
2547 do {
2548 retry_gc = false;
2549
2550 {
2551 MutexLocker ml(Heap_lock);
2552
2553 // Read the GC count while holding the Heap_lock
2554 gc_count_before = total_collections();
2555 old_marking_count_before = _old_marking_cycles_started;
2556 }
2557
2558 if (should_do_concurrent_full_gc(cause)) {
2559 // Schedule an initial-mark evacuation pause that will start a
2560 // concurrent cycle. We're setting word_size to 0 which means that
2561 // we are not requesting a post-GC allocation.
2562 VM_G1IncCollectionPause op(gc_count_before,
2563 0, /* word_size */
2564 true, /* should_initiate_conc_mark */
2565 g1_policy()->max_pause_time_ms(),
2566 cause);
2567
2568 VMThread::execute(&op);
2569 if (!op.pause_succeeded()) {
2570 if (old_marking_count_before == _old_marking_cycles_started) {
2571 retry_gc = op.should_retry_gc();
2572 } else {
2573 // A Full GC happened while we were trying to schedule the
2574 // initial-mark GC. No point in starting a new cycle given
2575 // that the whole heap was collected anyway.
2576 }
2577
2578 if (retry_gc) {
2579 if (GC_locker::is_active_and_needs_gc()) {
2580 GC_locker::stall_until_clear();
2581 }
2582 }
2583 }
2584 } else {
2585 if (cause == GCCause::_gc_locker
2586 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2587
2588 // Schedule a standard evacuation pause. We're setting word_size
2589 // to 0 which means that we are not requesting a post-GC allocation.
2590 VM_G1IncCollectionPause op(gc_count_before,
2591 0, /* word_size */
2592 false, /* should_initiate_conc_mark */
2593 g1_policy()->max_pause_time_ms(),
2594 cause);
2595 VMThread::execute(&op);
2596 } else {
2597 // Schedule a Full GC.
2598 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2599 VMThread::execute(&op);
2600 }
2601 }
2602 } while (retry_gc);
2603 }
2604
2605 bool G1CollectedHeap::is_in(const void* p) const {
2606 if (_g1_committed.contains(p)) {
2607 // Given that we know that p is in the committed space,
2608 // heap_region_containing_raw() should successfully
2609 // return the containing region.
2610 HeapRegion* hr = heap_region_containing_raw(p);
2611 return hr->is_in(p);
2612 } else {
2613 return false;
2614 }
2615 }
2616
2617 // Iteration functions.
2618
2619 // Iterates an OopClosure over all ref-containing fields of objects
2620 // within a HeapRegion.
2621
2622 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2623 MemRegion _mr;
2624 ExtendedOopClosure* _cl;
2625 public:
2626 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2627 : _mr(mr), _cl(cl) {}
2628 bool doHeapRegion(HeapRegion* r) {
2629 if (!r->continuesHumongous()) {
2630 r->oop_iterate(_cl);
2631 }
2632 return false;
2633 }
2634 };
2635
2636 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2637 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2638 heap_region_iterate(&blk);
2639 }
2640
2641 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2642 IterateOopClosureRegionClosure blk(mr, cl);
2643 heap_region_iterate(&blk);
2644 }
2645
2646 // Iterates an ObjectClosure over all objects within a HeapRegion.
2647
2648 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2649 ObjectClosure* _cl;
2650 public:
2651 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2652 bool doHeapRegion(HeapRegion* r) {
2653 if (! r->continuesHumongous()) {
2654 r->object_iterate(_cl);
2655 }
2656 return false;
2657 }
2658 };
2659
2660 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2661 IterateObjectClosureRegionClosure blk(cl);
2662 heap_region_iterate(&blk);
2663 }
2664
2665 // Calls a SpaceClosure on a HeapRegion.
2666
2667 class SpaceClosureRegionClosure: public HeapRegionClosure {
2668 SpaceClosure* _cl;
2669 public:
2670 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2671 bool doHeapRegion(HeapRegion* r) {
2672 _cl->do_space(r);
2673 return false;
2674 }
2675 };
2676
2677 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2678 SpaceClosureRegionClosure blk(cl);
2679 heap_region_iterate(&blk);
2680 }
2681
2682 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2683 _hrs.iterate(cl);
2684 }
2685
2686 void
2687 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2688 uint worker_id,
2689 uint no_of_par_workers,
2690 jint claim_value) {
2691 const uint regions = n_regions();
2692 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2693 no_of_par_workers :
2694 1);
2695 assert(UseDynamicNumberOfGCThreads ||
2696 no_of_par_workers == workers()->total_workers(),
2697 "Non dynamic should use fixed number of workers");
2698 // try to spread out the starting points of the workers
2699 const HeapRegion* start_hr =
2700 start_region_for_worker(worker_id, no_of_par_workers);
2701 const uint start_index = start_hr->hrs_index();
2702
2703 // each worker will actually look at all regions
2704 for (uint count = 0; count < regions; ++count) {
2705 const uint index = (start_index + count) % regions;
2706 assert(0 <= index && index < regions, "sanity");
2707 HeapRegion* r = region_at(index);
2708 // we'll ignore "continues humongous" regions (we'll process them
2709 // when we come across their corresponding "start humongous"
2710 // region) and regions already claimed
2711 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2712 continue;
2713 }
2714 // OK, try to claim it
2715 if (r->claimHeapRegion(claim_value)) {
2716 // success!
2717 assert(!r->continuesHumongous(), "sanity");
2718 if (r->startsHumongous()) {
2719 // If the region is "starts humongous" we'll iterate over its
2720 // "continues humongous" first; in fact we'll do them
2721 // first. The order is important. In on case, calling the
2722 // closure on the "starts humongous" region might de-allocate
2723 // and clear all its "continues humongous" regions and, as a
2724 // result, we might end up processing them twice. So, we'll do
2725 // them first (notice: most closures will ignore them anyway) and
2726 // then we'll do the "starts humongous" region.
2727 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2728 HeapRegion* chr = region_at(ch_index);
2729
2730 // if the region has already been claimed or it's not
2731 // "continues humongous" we're done
2732 if (chr->claim_value() == claim_value ||
2733 !chr->continuesHumongous()) {
2734 break;
2735 }
2736
2737 // No one should have claimed it directly. We can given
2738 // that we claimed its "starts humongous" region.
2739 assert(chr->claim_value() != claim_value, "sanity");
2740 assert(chr->humongous_start_region() == r, "sanity");
2741
2742 if (chr->claimHeapRegion(claim_value)) {
2743 // we should always be able to claim it; no one else should
2744 // be trying to claim this region
2745
2746 bool res2 = cl->doHeapRegion(chr);
2747 assert(!res2, "Should not abort");
2748
2749 // Right now, this holds (i.e., no closure that actually
2750 // does something with "continues humongous" regions
2751 // clears them). We might have to weaken it in the future,
2752 // but let's leave these two asserts here for extra safety.
2753 assert(chr->continuesHumongous(), "should still be the case");
2754 assert(chr->humongous_start_region() == r, "sanity");
2755 } else {
2756 guarantee(false, "we should not reach here");
2757 }
2758 }
2759 }
2760
2761 assert(!r->continuesHumongous(), "sanity");
2762 bool res = cl->doHeapRegion(r);
2763 assert(!res, "Should not abort");
2764 }
2765 }
2766 }
2767
2768 class ResetClaimValuesClosure: public HeapRegionClosure {
2769 public:
2770 bool doHeapRegion(HeapRegion* r) {
2771 r->set_claim_value(HeapRegion::InitialClaimValue);
2772 return false;
2773 }
2774 };
2775
2776 void G1CollectedHeap::reset_heap_region_claim_values() {
2777 ResetClaimValuesClosure blk;
2778 heap_region_iterate(&blk);
2779 }
2780
2781 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2782 ResetClaimValuesClosure blk;
2783 collection_set_iterate(&blk);
2784 }
2785
2786 #ifdef ASSERT
2787 // This checks whether all regions in the heap have the correct claim
2788 // value. I also piggy-backed on this a check to ensure that the
2789 // humongous_start_region() information on "continues humongous"
2790 // regions is correct.
2791
2792 class CheckClaimValuesClosure : public HeapRegionClosure {
2793 private:
2794 jint _claim_value;
2795 uint _failures;
2796 HeapRegion* _sh_region;
2797
2798 public:
2799 CheckClaimValuesClosure(jint claim_value) :
2800 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2801 bool doHeapRegion(HeapRegion* r) {
2802 if (r->claim_value() != _claim_value) {
2803 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2804 "claim value = %d, should be %d",
2805 HR_FORMAT_PARAMS(r),
2806 r->claim_value(), _claim_value);
2807 ++_failures;
2808 }
2809 if (!r->isHumongous()) {
2810 _sh_region = NULL;
2811 } else if (r->startsHumongous()) {
2812 _sh_region = r;
2813 } else if (r->continuesHumongous()) {
2814 if (r->humongous_start_region() != _sh_region) {
2815 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2816 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2817 HR_FORMAT_PARAMS(r),
2818 r->humongous_start_region(),
2819 _sh_region);
2820 ++_failures;
2821 }
2822 }
2823 return false;
2824 }
2825 uint failures() { return _failures; }
2826 };
2827
2828 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2829 CheckClaimValuesClosure cl(claim_value);
2830 heap_region_iterate(&cl);
2831 return cl.failures() == 0;
2832 }
2833
2834 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2835 private:
2836 jint _claim_value;
2837 uint _failures;
2838
2839 public:
2840 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2841 _claim_value(claim_value), _failures(0) { }
2842
2843 uint failures() { return _failures; }
2844
2845 bool doHeapRegion(HeapRegion* hr) {
2846 assert(hr->in_collection_set(), "how?");
2847 assert(!hr->isHumongous(), "H-region in CSet");
2848 if (hr->claim_value() != _claim_value) {
2849 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2850 "claim value = %d, should be %d",
2851 HR_FORMAT_PARAMS(hr),
2852 hr->claim_value(), _claim_value);
2853 _failures += 1;
2854 }
2855 return false;
2856 }
2857 };
2858
2859 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2860 CheckClaimValuesInCSetHRClosure cl(claim_value);
2861 collection_set_iterate(&cl);
2862 return cl.failures() == 0;
2863 }
2864 #endif // ASSERT
2865
2866 // Clear the cached CSet starting regions and (more importantly)
2867 // the time stamps. Called when we reset the GC time stamp.
2868 void G1CollectedHeap::clear_cset_start_regions() {
2869 assert(_worker_cset_start_region != NULL, "sanity");
2870 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2871
2872 int n_queues = MAX2((int)ParallelGCThreads, 1);
2873 for (int i = 0; i < n_queues; i++) {
2874 _worker_cset_start_region[i] = NULL;
2875 _worker_cset_start_region_time_stamp[i] = 0;
2876 }
2877 }
2878
2879 // Given the id of a worker, obtain or calculate a suitable
2880 // starting region for iterating over the current collection set.
2881 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2882 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2883
2884 HeapRegion* result = NULL;
2885 unsigned gc_time_stamp = get_gc_time_stamp();
2886
2887 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2888 // Cached starting region for current worker was set
2889 // during the current pause - so it's valid.
2890 // Note: the cached starting heap region may be NULL
2891 // (when the collection set is empty).
2892 result = _worker_cset_start_region[worker_i];
2893 assert(result == NULL || result->in_collection_set(), "sanity");
2894 return result;
2895 }
2896
2897 // The cached entry was not valid so let's calculate
2898 // a suitable starting heap region for this worker.
2899
2900 // We want the parallel threads to start their collection
2901 // set iteration at different collection set regions to
2902 // avoid contention.
2903 // If we have:
2904 // n collection set regions
2905 // p threads
2906 // Then thread t will start at region floor ((t * n) / p)
2907
2908 result = g1_policy()->collection_set();
2909 if (G1CollectedHeap::use_parallel_gc_threads()) {
2910 uint cs_size = g1_policy()->cset_region_length();
2911 uint active_workers = workers()->active_workers();
2912 assert(UseDynamicNumberOfGCThreads ||
2913 active_workers == workers()->total_workers(),
2914 "Unless dynamic should use total workers");
2915
2916 uint end_ind = (cs_size * worker_i) / active_workers;
2917 uint start_ind = 0;
2918
2919 if (worker_i > 0 &&
2920 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2921 // Previous workers starting region is valid
2922 // so let's iterate from there
2923 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2924 result = _worker_cset_start_region[worker_i - 1];
2925 }
2926
2927 for (uint i = start_ind; i < end_ind; i++) {
2928 result = result->next_in_collection_set();
2929 }
2930 }
2931
2932 // Note: the calculated starting heap region may be NULL
2933 // (when the collection set is empty).
2934 assert(result == NULL || result->in_collection_set(), "sanity");
2935 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2936 "should be updated only once per pause");
2937 _worker_cset_start_region[worker_i] = result;
2938 OrderAccess::storestore();
2939 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2940 return result;
2941 }
2942
2943 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2944 uint no_of_par_workers) {
2945 uint worker_num =
2946 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2947 assert(UseDynamicNumberOfGCThreads ||
2948 no_of_par_workers == workers()->total_workers(),
2949 "Non dynamic should use fixed number of workers");
2950 const uint start_index = n_regions() * worker_i / worker_num;
2951 return region_at(start_index);
2952 }
2953
2954 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2955 HeapRegion* r = g1_policy()->collection_set();
2956 while (r != NULL) {
2957 HeapRegion* next = r->next_in_collection_set();
2958 if (cl->doHeapRegion(r)) {
2959 cl->incomplete();
2960 return;
2961 }
2962 r = next;
2963 }
2964 }
2965
2966 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2967 HeapRegionClosure *cl) {
2968 if (r == NULL) {
2969 // The CSet is empty so there's nothing to do.
2970 return;
2971 }
2972
2973 assert(r->in_collection_set(),
2974 "Start region must be a member of the collection set.");
2975 HeapRegion* cur = r;
2976 while (cur != NULL) {
2977 HeapRegion* next = cur->next_in_collection_set();
2978 if (cl->doHeapRegion(cur) && false) {
2979 cl->incomplete();
2980 return;
2981 }
2982 cur = next;
2983 }
2984 cur = g1_policy()->collection_set();
2985 while (cur != r) {
2986 HeapRegion* next = cur->next_in_collection_set();
2987 if (cl->doHeapRegion(cur) && false) {
2988 cl->incomplete();
2989 return;
2990 }
2991 cur = next;
2992 }
2993 }
2994
2995 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2996 return n_regions() > 0 ? region_at(0) : NULL;
2997 }
2998
2999
3000 Space* G1CollectedHeap::space_containing(const void* addr) const {
3001 Space* res = heap_region_containing(addr);
3002 return res;
3003 }
3004
3005 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
3006 Space* sp = space_containing(addr);
3007 if (sp != NULL) {
3008 return sp->block_start(addr);
3009 }
3010 return NULL;
3011 }
3012
3013 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3014 Space* sp = space_containing(addr);
3015 assert(sp != NULL, "block_size of address outside of heap");
3016 return sp->block_size(addr);
3017 }
3018
3019 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3020 Space* sp = space_containing(addr);
3021 return sp->block_is_obj(addr);
3022 }
3023
3024 bool G1CollectedHeap::supports_tlab_allocation() const {
3025 return true;
3026 }
3027
3028 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3029 return HeapRegion::GrainBytes;
3030 }
3031
3032 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3033 // Return the remaining space in the cur alloc region, but not less than
3034 // the min TLAB size.
3035
3036 // Also, this value can be at most the humongous object threshold,
3037 // since we can't allow tlabs to grow big enough to accommodate
3038 // humongous objects.
3039
3040 HeapRegion* hr = _mutator_alloc_region.get();
3041 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3042 if (hr == NULL) {
3043 return max_tlab_size;
3044 } else {
3045 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3046 }
3047 }
3048
3049 size_t G1CollectedHeap::max_capacity() const {
3050 return _g1_reserved.byte_size();
3051 }
3052
3053 jlong G1CollectedHeap::millis_since_last_gc() {
3054 // assert(false, "NYI");
3055 return 0;
3056 }
3057
3058 void G1CollectedHeap::prepare_for_verify() {
3059 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3060 ensure_parsability(false);
3061 }
3062 g1_rem_set()->prepare_for_verify();
3063 }
3064
3065 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3066 VerifyOption vo) {
3067 switch (vo) {
3068 case VerifyOption_G1UsePrevMarking:
3069 return hr->obj_allocated_since_prev_marking(obj);
3070 case VerifyOption_G1UseNextMarking:
3071 return hr->obj_allocated_since_next_marking(obj);
3072 case VerifyOption_G1UseMarkWord:
3073 return false;
3074 default:
3075 ShouldNotReachHere();
3076 }
3077 return false; // keep some compilers happy
3078 }
3079
3080 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3081 switch (vo) {
3082 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3083 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3084 case VerifyOption_G1UseMarkWord: return NULL;
3085 default: ShouldNotReachHere();
3086 }
3087 return NULL; // keep some compilers happy
3088 }
3089
3090 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3091 switch (vo) {
3092 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3093 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3094 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3095 default: ShouldNotReachHere();
3096 }
3097 return false; // keep some compilers happy
3098 }
3099
3100 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3101 switch (vo) {
3102 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3103 case VerifyOption_G1UseNextMarking: return "NTAMS";
3104 case VerifyOption_G1UseMarkWord: return "NONE";
3105 default: ShouldNotReachHere();
3106 }
3107 return NULL; // keep some compilers happy
3108 }
3109
3110 class VerifyLivenessOopClosure: public OopClosure {
3111 G1CollectedHeap* _g1h;
3112 VerifyOption _vo;
3113 public:
3114 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3115 _g1h(g1h), _vo(vo)
3116 { }
3117 void do_oop(narrowOop *p) { do_oop_work(p); }
3118 void do_oop( oop *p) { do_oop_work(p); }
3119
3120 template <class T> void do_oop_work(T *p) {
3121 oop obj = oopDesc::load_decode_heap_oop(p);
3122 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3123 "Dead object referenced by a not dead object");
3124 }
3125 };
3126
3127 class VerifyObjsInRegionClosure: public ObjectClosure {
3128 private:
3129 G1CollectedHeap* _g1h;
3130 size_t _live_bytes;
3131 HeapRegion *_hr;
3132 VerifyOption _vo;
3133 public:
3134 // _vo == UsePrevMarking -> use "prev" marking information,
3135 // _vo == UseNextMarking -> use "next" marking information,
3136 // _vo == UseMarkWord -> use mark word from object header.
3137 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3138 : _live_bytes(0), _hr(hr), _vo(vo) {
3139 _g1h = G1CollectedHeap::heap();
3140 }
3141 void do_object(oop o) {
3142 VerifyLivenessOopClosure isLive(_g1h, _vo);
3143 assert(o != NULL, "Huh?");
3144 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3145 // If the object is alive according to the mark word,
3146 // then verify that the marking information agrees.
3147 // Note we can't verify the contra-positive of the
3148 // above: if the object is dead (according to the mark
3149 // word), it may not be marked, or may have been marked
3150 // but has since became dead, or may have been allocated
3151 // since the last marking.
3152 if (_vo == VerifyOption_G1UseMarkWord) {
3153 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3154 }
3155
3156 o->oop_iterate_no_header(&isLive);
3157 if (!_hr->obj_allocated_since_prev_marking(o)) {
3158 size_t obj_size = o->size(); // Make sure we don't overflow
3159 _live_bytes += (obj_size * HeapWordSize);
3160 }
3161 }
3162 }
3163 size_t live_bytes() { return _live_bytes; }
3164 };
3165
3166 class PrintObjsInRegionClosure : public ObjectClosure {
3167 HeapRegion *_hr;
3168 G1CollectedHeap *_g1;
3169 public:
3170 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3171 _g1 = G1CollectedHeap::heap();
3172 };
3173
3174 void do_object(oop o) {
3175 if (o != NULL) {
3176 HeapWord *start = (HeapWord *) o;
3177 size_t word_sz = o->size();
3178 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3179 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3180 (void*) o, word_sz,
3181 _g1->isMarkedPrev(o),
3182 _g1->isMarkedNext(o),
3183 _hr->obj_allocated_since_prev_marking(o));
3184 HeapWord *end = start + word_sz;
3185 HeapWord *cur;
3186 int *val;
3187 for (cur = start; cur < end; cur++) {
3188 val = (int *) cur;
3189 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3190 }
3191 }
3192 }
3193 };
3194
3195 class VerifyRegionClosure: public HeapRegionClosure {
3196 private:
3197 bool _par;
3198 VerifyOption _vo;
3199 bool _failures;
3200 public:
3201 // _vo == UsePrevMarking -> use "prev" marking information,
3202 // _vo == UseNextMarking -> use "next" marking information,
3203 // _vo == UseMarkWord -> use mark word from object header.
3204 VerifyRegionClosure(bool par, VerifyOption vo)
3205 : _par(par),
3206 _vo(vo),
3207 _failures(false) {}
3208
3209 bool failures() {
3210 return _failures;
3211 }
3212
3213 bool doHeapRegion(HeapRegion* r) {
3214 if (!r->continuesHumongous()) {
3215 bool failures = false;
3216 r->verify(_vo, &failures);
3217 if (failures) {
3218 _failures = true;
3219 } else {
3220 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3221 r->object_iterate(¬_dead_yet_cl);
3222 if (_vo != VerifyOption_G1UseNextMarking) {
3223 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3224 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3225 "max_live_bytes "SIZE_FORMAT" "
3226 "< calculated "SIZE_FORMAT,
3227 r->bottom(), r->end(),
3228 r->max_live_bytes(),
3229 not_dead_yet_cl.live_bytes());
3230 _failures = true;
3231 }
3232 } else {
3233 // When vo == UseNextMarking we cannot currently do a sanity
3234 // check on the live bytes as the calculation has not been
3235 // finalized yet.
3236 }
3237 }
3238 }
3239 return false; // stop the region iteration if we hit a failure
3240 }
3241 };
3242
3243 class YoungRefCounterClosure : public OopClosure {
3244 G1CollectedHeap* _g1h;
3245 int _count;
3246 public:
3247 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3248 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3249 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3250
3251 int count() { return _count; }
3252 void reset_count() { _count = 0; };
3253 };
3254
3255 class VerifyKlassClosure: public KlassClosure {
3256 YoungRefCounterClosure _young_ref_counter_closure;
3257 OopClosure *_oop_closure;
3258 public:
3259 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3260 void do_klass(Klass* k) {
3261 k->oops_do(_oop_closure);
3262
3263 _young_ref_counter_closure.reset_count();
3264 k->oops_do(&_young_ref_counter_closure);
3265 if (_young_ref_counter_closure.count() > 0) {
3266 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3267 }
3268 }
3269 };
3270
3271 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3272 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3273 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3274 // we can change this closure to extend the simpler OopClosure.
3275 class VerifyRootsClosure: public OopsInGenClosure {
3276 private:
3277 G1CollectedHeap* _g1h;
3278 VerifyOption _vo;
3279 bool _failures;
3280 public:
3281 // _vo == UsePrevMarking -> use "prev" marking information,
3282 // _vo == UseNextMarking -> use "next" marking information,
3283 // _vo == UseMarkWord -> use mark word from object header.
3284 VerifyRootsClosure(VerifyOption vo) :
3285 _g1h(G1CollectedHeap::heap()),
3286 _vo(vo),
3287 _failures(false) { }
3288
3289 bool failures() { return _failures; }
3290
3291 template <class T> void do_oop_nv(T* p) {
3292 T heap_oop = oopDesc::load_heap_oop(p);
3293 if (!oopDesc::is_null(heap_oop)) {
3294 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3295 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3296 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3297 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3298 if (_vo == VerifyOption_G1UseMarkWord) {
3299 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3300 }
3301 obj->print_on(gclog_or_tty);
3302 _failures = true;
3303 }
3304 }
3305 }
3306
3307 void do_oop(oop* p) { do_oop_nv(p); }
3308 void do_oop(narrowOop* p) { do_oop_nv(p); }
3309 };
3310
3311 // This is the task used for parallel heap verification.
3312
3313 class G1ParVerifyTask: public AbstractGangTask {
3314 private:
3315 G1CollectedHeap* _g1h;
3316 VerifyOption _vo;
3317 bool _failures;
3318
3319 public:
3320 // _vo == UsePrevMarking -> use "prev" marking information,
3321 // _vo == UseNextMarking -> use "next" marking information,
3322 // _vo == UseMarkWord -> use mark word from object header.
3323 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3324 AbstractGangTask("Parallel verify task"),
3325 _g1h(g1h),
3326 _vo(vo),
3327 _failures(false) { }
3328
3329 bool failures() {
3330 return _failures;
3331 }
3332
3333 void work(uint worker_id) {
3334 HandleMark hm;
3335 VerifyRegionClosure blk(true, _vo);
3336 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3337 _g1h->workers()->active_workers(),
3338 HeapRegion::ParVerifyClaimValue);
3339 if (blk.failures()) {
3340 _failures = true;
3341 }
3342 }
3343 };
3344
3345 void G1CollectedHeap::verify(bool silent) {
3346 verify(silent, VerifyOption_G1UsePrevMarking);
3347 }
3348
3349 void G1CollectedHeap::verify(bool silent,
3350 VerifyOption vo) {
3351 if (SafepointSynchronize::is_at_safepoint()) {
3352 if (!silent) { gclog_or_tty->print("Roots "); }
3353 VerifyRootsClosure rootsCl(vo);
3354
3355 assert(Thread::current()->is_VM_thread(),
3356 "Expected to be executed serially by the VM thread at this point");
3357
3358 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3359 VerifyKlassClosure klassCl(this, &rootsCl);
3360
3361 // We apply the relevant closures to all the oops in the
3362 // system dictionary, the string table and the code cache.
3363 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3364
3365 // Need cleared claim bits for the strong roots processing
3366 ClassLoaderDataGraph::clear_claimed_marks();
3367
3368 process_strong_roots(true, // activate StrongRootsScope
3369 false, // we set "is scavenging" to false,
3370 // so we don't reset the dirty cards.
3371 ScanningOption(so), // roots scanning options
3372 &rootsCl,
3373 &blobsCl,
3374 &klassCl
3375 );
3376
3377 bool failures = rootsCl.failures();
3378
3379 if (vo != VerifyOption_G1UseMarkWord) {
3380 // If we're verifying during a full GC then the region sets
3381 // will have been torn down at the start of the GC. Therefore
3382 // verifying the region sets will fail. So we only verify
3383 // the region sets when not in a full GC.
3384 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3385 verify_region_sets();
3386 }
3387
3388 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3389 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3390 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3391 "sanity check");
3392
3393 G1ParVerifyTask task(this, vo);
3394 assert(UseDynamicNumberOfGCThreads ||
3395 workers()->active_workers() == workers()->total_workers(),
3396 "If not dynamic should be using all the workers");
3397 int n_workers = workers()->active_workers();
3398 set_par_threads(n_workers);
3399 workers()->run_task(&task);
3400 set_par_threads(0);
3401 if (task.failures()) {
3402 failures = true;
3403 }
3404
3405 // Checks that the expected amount of parallel work was done.
3406 // The implication is that n_workers is > 0.
3407 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3408 "sanity check");
3409
3410 reset_heap_region_claim_values();
3411
3412 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3413 "sanity check");
3414 } else {
3415 VerifyRegionClosure blk(false, vo);
3416 heap_region_iterate(&blk);
3417 if (blk.failures()) {
3418 failures = true;
3419 }
3420 }
3421 if (!silent) gclog_or_tty->print("RemSet ");
3422 rem_set()->verify();
3423
3424 if (failures) {
3425 gclog_or_tty->print_cr("Heap:");
3426 // It helps to have the per-region information in the output to
3427 // help us track down what went wrong. This is why we call
3428 // print_extended_on() instead of print_on().
3429 print_extended_on(gclog_or_tty);
3430 gclog_or_tty->print_cr("");
3431 #ifndef PRODUCT
3432 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3433 concurrent_mark()->print_reachable("at-verification-failure",
3434 vo, false /* all */);
3435 }
3436 #endif
3437 gclog_or_tty->flush();
3438 }
3439 guarantee(!failures, "there should not have been any failures");
3440 } else {
3441 if (!silent)
3442 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3443 }
3444 }
3445
3446 class PrintRegionClosure: public HeapRegionClosure {
3447 outputStream* _st;
3448 public:
3449 PrintRegionClosure(outputStream* st) : _st(st) {}
3450 bool doHeapRegion(HeapRegion* r) {
3451 r->print_on(_st);
3452 return false;
3453 }
3454 };
3455
3456 void G1CollectedHeap::print_on(outputStream* st) const {
3457 st->print(" %-20s", "garbage-first heap");
3458 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3459 capacity()/K, used_unlocked()/K);
3460 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3461 _g1_storage.low_boundary(),
3462 _g1_storage.high(),
3463 _g1_storage.high_boundary());
3464 st->cr();
3465 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3466 uint young_regions = _young_list->length();
3467 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3468 (size_t) young_regions * HeapRegion::GrainBytes / K);
3469 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3470 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3471 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3472 st->cr();
3473 MetaspaceAux::print_on(st);
3474 }
3475
3476 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3477 print_on(st);
3478
3479 // Print the per-region information.
3480 st->cr();
3481 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3482 "HS=humongous(starts), HC=humongous(continues), "
3483 "CS=collection set, F=free, TS=gc time stamp, "
3484 "PTAMS=previous top-at-mark-start, "
3485 "NTAMS=next top-at-mark-start)");
3486 PrintRegionClosure blk(st);
3487 heap_region_iterate(&blk);
3488 }
3489
3490 void G1CollectedHeap::print_on_error(outputStream* st) const {
3491 this->CollectedHeap::print_on_error(st);
3492
3493 if (_cm != NULL) {
3494 st->cr();
3495 _cm->print_on_error(st);
3496 }
3497 }
3498
3499 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3500 if (G1CollectedHeap::use_parallel_gc_threads()) {
3501 workers()->print_worker_threads_on(st);
3502 }
3503 _cmThread->print_on(st);
3504 st->cr();
3505 _cm->print_worker_threads_on(st);
3506 _cg1r->print_worker_threads_on(st);
3507 }
3508
3509 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3510 if (G1CollectedHeap::use_parallel_gc_threads()) {
3511 workers()->threads_do(tc);
3512 }
3513 tc->do_thread(_cmThread);
3514 _cg1r->threads_do(tc);
3515 }
3516
3517 void G1CollectedHeap::print_tracing_info() const {
3518 // We'll overload this to mean "trace GC pause statistics."
3519 if (TraceGen0Time || TraceGen1Time) {
3520 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3521 // to that.
3522 g1_policy()->print_tracing_info();
3523 }
3524 if (G1SummarizeRSetStats) {
3525 g1_rem_set()->print_summary_info();
3526 }
3527 if (G1SummarizeConcMark) {
3528 concurrent_mark()->print_summary_info();
3529 }
3530 g1_policy()->print_yg_surv_rate_info();
3531 SpecializationStats::print();
3532 }
3533
3534 #ifndef PRODUCT
3535 // Helpful for debugging RSet issues.
3536
3537 class PrintRSetsClosure : public HeapRegionClosure {
3538 private:
3539 const char* _msg;
3540 size_t _occupied_sum;
3541
3542 public:
3543 bool doHeapRegion(HeapRegion* r) {
3544 HeapRegionRemSet* hrrs = r->rem_set();
3545 size_t occupied = hrrs->occupied();
3546 _occupied_sum += occupied;
3547
3548 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3549 HR_FORMAT_PARAMS(r));
3550 if (occupied == 0) {
3551 gclog_or_tty->print_cr(" RSet is empty");
3552 } else {
3553 hrrs->print();
3554 }
3555 gclog_or_tty->print_cr("----------");
3556 return false;
3557 }
3558
3559 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3560 gclog_or_tty->cr();
3561 gclog_or_tty->print_cr("========================================");
3562 gclog_or_tty->print_cr(msg);
3563 gclog_or_tty->cr();
3564 }
3565
3566 ~PrintRSetsClosure() {
3567 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3568 gclog_or_tty->print_cr("========================================");
3569 gclog_or_tty->cr();
3570 }
3571 };
3572
3573 void G1CollectedHeap::print_cset_rsets() {
3574 PrintRSetsClosure cl("Printing CSet RSets");
3575 collection_set_iterate(&cl);
3576 }
3577
3578 void G1CollectedHeap::print_all_rsets() {
3579 PrintRSetsClosure cl("Printing All RSets");;
3580 heap_region_iterate(&cl);
3581 }
3582 #endif // PRODUCT
3583
3584 G1CollectedHeap* G1CollectedHeap::heap() {
3585 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3586 "not a garbage-first heap");
3587 return _g1h;
3588 }
3589
3590 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3591 // always_do_update_barrier = false;
3592 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3593 // Fill TLAB's and such
3594 ensure_parsability(true);
3595 }
3596
3597 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3598
3599 if (G1SummarizeRSetStats &&
3600 (G1SummarizeRSetStatsPeriod > 0) &&
3601 // we are at the end of the GC. Total collections has already been increased.
3602 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3603 g1_rem_set()->print_periodic_summary_info();
3604 }
3605
3606 // FIXME: what is this about?
3607 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3608 // is set.
3609 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3610 "derived pointer present"));
3611 // always_do_update_barrier = true;
3612
3613 // We have just completed a GC. Update the soft reference
3614 // policy with the new heap occupancy
3615 Universe::update_heap_info_at_gc();
3616 }
3617
3618 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3619 unsigned int gc_count_before,
3620 bool* succeeded) {
3621 assert_heap_not_locked_and_not_at_safepoint();
3622 g1_policy()->record_stop_world_start();
3623 VM_G1IncCollectionPause op(gc_count_before,
3624 word_size,
3625 false, /* should_initiate_conc_mark */
3626 g1_policy()->max_pause_time_ms(),
3627 GCCause::_g1_inc_collection_pause);
3628 VMThread::execute(&op);
3629
3630 HeapWord* result = op.result();
3631 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3632 assert(result == NULL || ret_succeeded,
3633 "the result should be NULL if the VM did not succeed");
3634 *succeeded = ret_succeeded;
3635
3636 assert_heap_not_locked();
3637 return result;
3638 }
3639
3640 void
3641 G1CollectedHeap::doConcurrentMark() {
3642 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3643 if (!_cmThread->in_progress()) {
3644 _cmThread->set_started();
3645 CGC_lock->notify();
3646 }
3647 }
3648
3649 size_t G1CollectedHeap::pending_card_num() {
3650 size_t extra_cards = 0;
3651 JavaThread *curr = Threads::first();
3652 while (curr != NULL) {
3653 DirtyCardQueue& dcq = curr->dirty_card_queue();
3654 extra_cards += dcq.size();
3655 curr = curr->next();
3656 }
3657 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3658 size_t buffer_size = dcqs.buffer_size();
3659 size_t buffer_num = dcqs.completed_buffers_num();
3660
3661 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3662 // in bytes - not the number of 'entries'. We need to convert
3663 // into a number of cards.
3664 return (buffer_size * buffer_num + extra_cards) / oopSize;
3665 }
3666
3667 size_t G1CollectedHeap::cards_scanned() {
3668 return g1_rem_set()->cardsScanned();
3669 }
3670
3671 void
3672 G1CollectedHeap::setup_surviving_young_words() {
3673 assert(_surviving_young_words == NULL, "pre-condition");
3674 uint array_length = g1_policy()->young_cset_region_length();
3675 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3676 if (_surviving_young_words == NULL) {
3677 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3678 "Not enough space for young surv words summary.");
3679 }
3680 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3681 #ifdef ASSERT
3682 for (uint i = 0; i < array_length; ++i) {
3683 assert( _surviving_young_words[i] == 0, "memset above" );
3684 }
3685 #endif // !ASSERT
3686 }
3687
3688 void
3689 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3690 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3691 uint array_length = g1_policy()->young_cset_region_length();
3692 for (uint i = 0; i < array_length; ++i) {
3693 _surviving_young_words[i] += surv_young_words[i];
3694 }
3695 }
3696
3697 void
3698 G1CollectedHeap::cleanup_surviving_young_words() {
3699 guarantee( _surviving_young_words != NULL, "pre-condition" );
3700 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3701 _surviving_young_words = NULL;
3702 }
3703
3704 #ifdef ASSERT
3705 class VerifyCSetClosure: public HeapRegionClosure {
3706 public:
3707 bool doHeapRegion(HeapRegion* hr) {
3708 // Here we check that the CSet region's RSet is ready for parallel
3709 // iteration. The fields that we'll verify are only manipulated
3710 // when the region is part of a CSet and is collected. Afterwards,
3711 // we reset these fields when we clear the region's RSet (when the
3712 // region is freed) so they are ready when the region is
3713 // re-allocated. The only exception to this is if there's an
3714 // evacuation failure and instead of freeing the region we leave
3715 // it in the heap. In that case, we reset these fields during
3716 // evacuation failure handling.
3717 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3718
3719 // Here's a good place to add any other checks we'd like to
3720 // perform on CSet regions.
3721 return false;
3722 }
3723 };
3724 #endif // ASSERT
3725
3726 #if TASKQUEUE_STATS
3727 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3728 st->print_raw_cr("GC Task Stats");
3729 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3730 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3731 }
3732
3733 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3734 print_taskqueue_stats_hdr(st);
3735
3736 TaskQueueStats totals;
3737 const int n = workers() != NULL ? workers()->total_workers() : 1;
3738 for (int i = 0; i < n; ++i) {
3739 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3740 totals += task_queue(i)->stats;
3741 }
3742 st->print_raw("tot "); totals.print(st); st->cr();
3743
3744 DEBUG_ONLY(totals.verify());
3745 }
3746
3747 void G1CollectedHeap::reset_taskqueue_stats() {
3748 const int n = workers() != NULL ? workers()->total_workers() : 1;
3749 for (int i = 0; i < n; ++i) {
3750 task_queue(i)->stats.reset();
3751 }
3752 }
3753 #endif // TASKQUEUE_STATS
3754
3755 void G1CollectedHeap::log_gc_header() {
3756 if (!G1Log::fine()) {
3757 return;
3758 }
3759
3760 gclog_or_tty->date_stamp(PrintGCDateStamps);
3761 gclog_or_tty->stamp(PrintGCTimeStamps);
3762
3763 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3764 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3765 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3766
3767 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3768 }
3769
3770 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3771 if (!G1Log::fine()) {
3772 return;
3773 }
3774
3775 if (G1Log::finer()) {
3776 if (evacuation_failed()) {
3777 gclog_or_tty->print(" (to-space exhausted)");
3778 }
3779 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3780 g1_policy()->phase_times()->note_gc_end();
3781 g1_policy()->phase_times()->print(pause_time_sec);
3782 g1_policy()->print_detailed_heap_transition();
3783 } else {
3784 if (evacuation_failed()) {
3785 gclog_or_tty->print("--");
3786 }
3787 g1_policy()->print_heap_transition();
3788 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3789 }
3790 gclog_or_tty->flush();
3791 }
3792
3793 bool
3794 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3795 assert_at_safepoint(true /* should_be_vm_thread */);
3796 guarantee(!is_gc_active(), "collection is not reentrant");
3797
3798 if (GC_locker::check_active_before_gc()) {
3799 return false;
3800 }
3801
3802 _gc_timer_stw->register_gc_start(os::elapsed_counter());
3803
3804 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3805
3806 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3807 ResourceMark rm;
3808
3809 print_heap_before_gc();
3810 trace_heap_before_gc(_gc_tracer_stw);
3811
3812 HRSPhaseSetter x(HRSPhaseEvacuation);
3813 verify_region_sets_optional();
3814 verify_dirty_young_regions();
3815
3816 // This call will decide whether this pause is an initial-mark
3817 // pause. If it is, during_initial_mark_pause() will return true
3818 // for the duration of this pause.
3819 g1_policy()->decide_on_conc_mark_initiation();
3820
3821 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3822 assert(!g1_policy()->during_initial_mark_pause() ||
3823 g1_policy()->gcs_are_young(), "sanity");
3824
3825 // We also do not allow mixed GCs during marking.
3826 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3827
3828 // Record whether this pause is an initial mark. When the current
3829 // thread has completed its logging output and it's safe to signal
3830 // the CM thread, the flag's value in the policy has been reset.
3831 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3832
3833 // Inner scope for scope based logging, timers, and stats collection
3834 {
3835 EvacuationInfo evacuation_info;
3836
3837 if (g1_policy()->during_initial_mark_pause()) {
3838 // We are about to start a marking cycle, so we increment the
3839 // full collection counter.
3840 increment_old_marking_cycles_started();
3841 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3842 }
3843
3844 _gc_tracer_stw->report_yc_type(yc_type());
3845
3846 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3847
3848 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3849 workers()->active_workers() : 1);
3850 double pause_start_sec = os::elapsedTime();
3851 g1_policy()->phase_times()->note_gc_start(active_workers);
3852 log_gc_header();
3853
3854 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3855 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3856
3857 // If the secondary_free_list is not empty, append it to the
3858 // free_list. No need to wait for the cleanup operation to finish;
3859 // the region allocation code will check the secondary_free_list
3860 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3861 // set, skip this step so that the region allocation code has to
3862 // get entries from the secondary_free_list.
3863 if (!G1StressConcRegionFreeing) {
3864 append_secondary_free_list_if_not_empty_with_lock();
3865 }
3866
3867 assert(check_young_list_well_formed(),
3868 "young list should be well formed");
3869
3870 // Don't dynamically change the number of GC threads this early. A value of
3871 // 0 is used to indicate serial work. When parallel work is done,
3872 // it will be set.
3873
3874 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3875 IsGCActiveMark x;
3876
3877 gc_prologue(false);
3878 increment_total_collections(false /* full gc */);
3879 increment_gc_time_stamp();
3880
3881 verify_before_gc();
3882
3883 COMPILER2_PRESENT(DerivedPointerTable::clear());
3884
3885 // Please see comment in g1CollectedHeap.hpp and
3886 // G1CollectedHeap::ref_processing_init() to see how
3887 // reference processing currently works in G1.
3888
3889 // Enable discovery in the STW reference processor
3890 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3891 true /*verify_no_refs*/);
3892
3893 {
3894 // We want to temporarily turn off discovery by the
3895 // CM ref processor, if necessary, and turn it back on
3896 // on again later if we do. Using a scoped
3897 // NoRefDiscovery object will do this.
3898 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3899
3900 // Forget the current alloc region (we might even choose it to be part
3901 // of the collection set!).
3902 release_mutator_alloc_region();
3903
3904 // We should call this after we retire the mutator alloc
3905 // region(s) so that all the ALLOC / RETIRE events are generated
3906 // before the start GC event.
3907 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3908
3909 // This timing is only used by the ergonomics to handle our pause target.
3910 // It is unclear why this should not include the full pause. We will
3911 // investigate this in CR 7178365.
3912 //
3913 // Preserving the old comment here if that helps the investigation:
3914 //
3915 // The elapsed time induced by the start time below deliberately elides
3916 // the possible verification above.
3917 double sample_start_time_sec = os::elapsedTime();
3918
3919 #if YOUNG_LIST_VERBOSE
3920 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3921 _young_list->print();
3922 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3923 #endif // YOUNG_LIST_VERBOSE
3924
3925 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3926
3927 double scan_wait_start = os::elapsedTime();
3928 // We have to wait until the CM threads finish scanning the
3929 // root regions as it's the only way to ensure that all the
3930 // objects on them have been correctly scanned before we start
3931 // moving them during the GC.
3932 bool waited = _cm->root_regions()->wait_until_scan_finished();
3933 double wait_time_ms = 0.0;
3934 if (waited) {
3935 double scan_wait_end = os::elapsedTime();
3936 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3937 }
3938 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3939
3940 #if YOUNG_LIST_VERBOSE
3941 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3942 _young_list->print();
3943 #endif // YOUNG_LIST_VERBOSE
3944
3945 if (g1_policy()->during_initial_mark_pause()) {
3946 concurrent_mark()->checkpointRootsInitialPre();
3947 }
3948
3949 #if YOUNG_LIST_VERBOSE
3950 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3951 _young_list->print();
3952 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3953 #endif // YOUNG_LIST_VERBOSE
3954
3955 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3956
3957 _cm->note_start_of_gc();
3958 // We should not verify the per-thread SATB buffers given that
3959 // we have not filtered them yet (we'll do so during the
3960 // GC). We also call this after finalize_cset() to
3961 // ensure that the CSet has been finalized.
3962 _cm->verify_no_cset_oops(true /* verify_stacks */,
3963 true /* verify_enqueued_buffers */,
3964 false /* verify_thread_buffers */,
3965 true /* verify_fingers */);
3966
3967 if (_hr_printer.is_active()) {
3968 HeapRegion* hr = g1_policy()->collection_set();
3969 while (hr != NULL) {
3970 G1HRPrinter::RegionType type;
3971 if (!hr->is_young()) {
3972 type = G1HRPrinter::Old;
3973 } else if (hr->is_survivor()) {
3974 type = G1HRPrinter::Survivor;
3975 } else {
3976 type = G1HRPrinter::Eden;
3977 }
3978 _hr_printer.cset(hr);
3979 hr = hr->next_in_collection_set();
3980 }
3981 }
3982
3983 #ifdef ASSERT
3984 VerifyCSetClosure cl;
3985 collection_set_iterate(&cl);
3986 #endif // ASSERT
3987
3988 setup_surviving_young_words();
3989
3990 // Initialize the GC alloc regions.
3991 init_gc_alloc_regions(evacuation_info);
3992
3993 // Actually do the work...
3994 evacuate_collection_set(evacuation_info);
3995
3996 // We do this to mainly verify the per-thread SATB buffers
3997 // (which have been filtered by now) since we didn't verify
3998 // them earlier. No point in re-checking the stacks / enqueued
3999 // buffers given that the CSet has not changed since last time
4000 // we checked.
4001 _cm->verify_no_cset_oops(false /* verify_stacks */,
4002 false /* verify_enqueued_buffers */,
4003 true /* verify_thread_buffers */,
4004 true /* verify_fingers */);
4005
4006 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4007 g1_policy()->clear_collection_set();
4008
4009 cleanup_surviving_young_words();
4010
4011 // Start a new incremental collection set for the next pause.
4012 g1_policy()->start_incremental_cset_building();
4013
4014 // Clear the _cset_fast_test bitmap in anticipation of adding
4015 // regions to the incremental collection set for the next
4016 // evacuation pause.
4017 clear_cset_fast_test();
4018
4019 _young_list->reset_sampled_info();
4020
4021 // Don't check the whole heap at this point as the
4022 // GC alloc regions from this pause have been tagged
4023 // as survivors and moved on to the survivor list.
4024 // Survivor regions will fail the !is_young() check.
4025 assert(check_young_list_empty(false /* check_heap */),
4026 "young list should be empty");
4027
4028 #if YOUNG_LIST_VERBOSE
4029 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4030 _young_list->print();
4031 #endif // YOUNG_LIST_VERBOSE
4032
4033 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4034 _young_list->first_survivor_region(),
4035 _young_list->last_survivor_region());
4036
4037 _young_list->reset_auxilary_lists();
4038
4039 if (evacuation_failed()) {
4040 _summary_bytes_used = recalculate_used();
4041 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4042 for (uint i = 0; i < n_queues; i++) {
4043 if (_evacuation_failed_info_array[i].has_failed()) {
4044 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4045 }
4046 }
4047 } else {
4048 // The "used" of the the collection set have already been subtracted
4049 // when they were freed. Add in the bytes evacuated.
4050 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4051 }
4052
4053 if (g1_policy()->during_initial_mark_pause()) {
4054 // We have to do this before we notify the CM threads that
4055 // they can start working to make sure that all the
4056 // appropriate initialization is done on the CM object.
4057 concurrent_mark()->checkpointRootsInitialPost();
4058 set_marking_started();
4059 // Note that we don't actually trigger the CM thread at
4060 // this point. We do that later when we're sure that
4061 // the current thread has completed its logging output.
4062 }
4063
4064 allocate_dummy_regions();
4065
4066 #if YOUNG_LIST_VERBOSE
4067 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4068 _young_list->print();
4069 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4070 #endif // YOUNG_LIST_VERBOSE
4071
4072 init_mutator_alloc_region();
4073
4074 {
4075 size_t expand_bytes = g1_policy()->expansion_amount();
4076 if (expand_bytes > 0) {
4077 size_t bytes_before = capacity();
4078 // No need for an ergo verbose message here,
4079 // expansion_amount() does this when it returns a value > 0.
4080 if (!expand(expand_bytes)) {
4081 // We failed to expand the heap so let's verify that
4082 // committed/uncommitted amount match the backing store
4083 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4084 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4085 }
4086 }
4087 }
4088
4089 // We redo the verification but now wrt to the new CSet which
4090 // has just got initialized after the previous CSet was freed.
4091 _cm->verify_no_cset_oops(true /* verify_stacks */,
4092 true /* verify_enqueued_buffers */,
4093 true /* verify_thread_buffers */,
4094 true /* verify_fingers */);
4095 _cm->note_end_of_gc();
4096
4097 // This timing is only used by the ergonomics to handle our pause target.
4098 // It is unclear why this should not include the full pause. We will
4099 // investigate this in CR 7178365.
4100 double sample_end_time_sec = os::elapsedTime();
4101 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4102 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4103
4104 MemoryService::track_memory_usage();
4105
4106 // In prepare_for_verify() below we'll need to scan the deferred
4107 // update buffers to bring the RSets up-to-date if
4108 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4109 // the update buffers we'll probably need to scan cards on the
4110 // regions we just allocated to (i.e., the GC alloc
4111 // regions). However, during the last GC we called
4112 // set_saved_mark() on all the GC alloc regions, so card
4113 // scanning might skip the [saved_mark_word()...top()] area of
4114 // those regions (i.e., the area we allocated objects into
4115 // during the last GC). But it shouldn't. Given that
4116 // saved_mark_word() is conditional on whether the GC time stamp
4117 // on the region is current or not, by incrementing the GC time
4118 // stamp here we invalidate all the GC time stamps on all the
4119 // regions and saved_mark_word() will simply return top() for
4120 // all the regions. This is a nicer way of ensuring this rather
4121 // than iterating over the regions and fixing them. In fact, the
4122 // GC time stamp increment here also ensures that
4123 // saved_mark_word() will return top() between pauses, i.e.,
4124 // during concurrent refinement. So we don't need the
4125 // is_gc_active() check to decided which top to use when
4126 // scanning cards (see CR 7039627).
4127 increment_gc_time_stamp();
4128
4129 verify_after_gc();
4130
4131 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4132 ref_processor_stw()->verify_no_references_recorded();
4133
4134 // CM reference discovery will be re-enabled if necessary.
4135 }
4136
4137 // We should do this after we potentially expand the heap so
4138 // that all the COMMIT events are generated before the end GC
4139 // event, and after we retire the GC alloc regions so that all
4140 // RETIRE events are generated before the end GC event.
4141 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4142
4143 if (mark_in_progress()) {
4144 concurrent_mark()->update_g1_committed();
4145 }
4146
4147 #ifdef TRACESPINNING
4148 ParallelTaskTerminator::print_termination_counts();
4149 #endif
4150
4151 gc_epilogue(false);
4152 }
4153
4154 // Print the remainder of the GC log output.
4155 log_gc_footer(os::elapsedTime() - pause_start_sec);
4156
4157 // It is not yet to safe to tell the concurrent mark to
4158 // start as we have some optional output below. We don't want the
4159 // output from the concurrent mark thread interfering with this
4160 // logging output either.
4161
4162 _hrs.verify_optional();
4163 verify_region_sets_optional();
4164
4165 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4166 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4167
4168 print_heap_after_gc();
4169 trace_heap_after_gc(_gc_tracer_stw);
4170
4171 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4172 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4173 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4174 // before any GC notifications are raised.
4175 g1mm()->update_sizes();
4176
4177 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4178 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4179 _gc_timer_stw->register_gc_end(os::elapsed_counter());
4180 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4181 }
4182 // It should now be safe to tell the concurrent mark thread to start
4183 // without its logging output interfering with the logging output
4184 // that came from the pause.
4185
4186 if (should_start_conc_mark) {
4187 // CAUTION: after the doConcurrentMark() call below,
4188 // the concurrent marking thread(s) could be running
4189 // concurrently with us. Make sure that anything after
4190 // this point does not assume that we are the only GC thread
4191 // running. Note: of course, the actual marking work will
4192 // not start until the safepoint itself is released in
4193 // ConcurrentGCThread::safepoint_desynchronize().
4194 doConcurrentMark();
4195 }
4196
4197 return true;
4198 }
4199
4200 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4201 {
4202 size_t gclab_word_size;
4203 switch (purpose) {
4204 case GCAllocForSurvived:
4205 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4206 break;
4207 case GCAllocForTenured:
4208 gclab_word_size = _old_plab_stats.desired_plab_sz();
4209 break;
4210 default:
4211 assert(false, "unknown GCAllocPurpose");
4212 gclab_word_size = _old_plab_stats.desired_plab_sz();
4213 break;
4214 }
4215
4216 // Prevent humongous PLAB sizes for two reasons:
4217 // * PLABs are allocated using a similar paths as oops, but should
4218 // never be in a humongous region
4219 // * Allowing humongous PLABs needlessly churns the region free lists
4220 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4221 }
4222
4223 void G1CollectedHeap::init_mutator_alloc_region() {
4224 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4225 _mutator_alloc_region.init();
4226 }
4227
4228 void G1CollectedHeap::release_mutator_alloc_region() {
4229 _mutator_alloc_region.release();
4230 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4231 }
4232
4233 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4234 assert_at_safepoint(true /* should_be_vm_thread */);
4235
4236 _survivor_gc_alloc_region.init();
4237 _old_gc_alloc_region.init();
4238 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4239 _retained_old_gc_alloc_region = NULL;
4240
4241 // We will discard the current GC alloc region if:
4242 // a) it's in the collection set (it can happen!),
4243 // b) it's already full (no point in using it),
4244 // c) it's empty (this means that it was emptied during
4245 // a cleanup and it should be on the free list now), or
4246 // d) it's humongous (this means that it was emptied
4247 // during a cleanup and was added to the free list, but
4248 // has been subsequently used to allocate a humongous
4249 // object that may be less than the region size).
4250 if (retained_region != NULL &&
4251 !retained_region->in_collection_set() &&
4252 !(retained_region->top() == retained_region->end()) &&
4253 !retained_region->is_empty() &&
4254 !retained_region->isHumongous()) {
4255 retained_region->set_saved_mark();
4256 // The retained region was added to the old region set when it was
4257 // retired. We have to remove it now, since we don't allow regions
4258 // we allocate to in the region sets. We'll re-add it later, when
4259 // it's retired again.
4260 _old_set.remove(retained_region);
4261 bool during_im = g1_policy()->during_initial_mark_pause();
4262 retained_region->note_start_of_copying(during_im);
4263 _old_gc_alloc_region.set(retained_region);
4264 _hr_printer.reuse(retained_region);
4265 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4266 }
4267 }
4268
4269 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4270 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4271 _old_gc_alloc_region.count());
4272 _survivor_gc_alloc_region.release();
4273 // If we have an old GC alloc region to release, we'll save it in
4274 // _retained_old_gc_alloc_region. If we don't
4275 // _retained_old_gc_alloc_region will become NULL. This is what we
4276 // want either way so no reason to check explicitly for either
4277 // condition.
4278 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4279
4280 if (ResizePLAB) {
4281 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4282 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4283 }
4284 }
4285
4286 void G1CollectedHeap::abandon_gc_alloc_regions() {
4287 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4288 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4289 _retained_old_gc_alloc_region = NULL;
4290 }
4291
4292 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4293 _drain_in_progress = false;
4294 set_evac_failure_closure(cl);
4295 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4296 }
4297
4298 void G1CollectedHeap::finalize_for_evac_failure() {
4299 assert(_evac_failure_scan_stack != NULL &&
4300 _evac_failure_scan_stack->length() == 0,
4301 "Postcondition");
4302 assert(!_drain_in_progress, "Postcondition");
4303 delete _evac_failure_scan_stack;
4304 _evac_failure_scan_stack = NULL;
4305 }
4306
4307 void G1CollectedHeap::remove_self_forwarding_pointers() {
4308 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4309
4310 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4311
4312 if (G1CollectedHeap::use_parallel_gc_threads()) {
4313 set_par_threads();
4314 workers()->run_task(&rsfp_task);
4315 set_par_threads(0);
4316 } else {
4317 rsfp_task.work(0);
4318 }
4319
4320 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4321
4322 // Reset the claim values in the regions in the collection set.
4323 reset_cset_heap_region_claim_values();
4324
4325 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4326
4327 // Now restore saved marks, if any.
4328 assert(_objs_with_preserved_marks.size() ==
4329 _preserved_marks_of_objs.size(), "Both or none.");
4330 while (!_objs_with_preserved_marks.is_empty()) {
4331 oop obj = _objs_with_preserved_marks.pop();
4332 markOop m = _preserved_marks_of_objs.pop();
4333 obj->set_mark(m);
4334 }
4335 _objs_with_preserved_marks.clear(true);
4336 _preserved_marks_of_objs.clear(true);
4337 }
4338
4339 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4340 _evac_failure_scan_stack->push(obj);
4341 }
4342
4343 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4344 assert(_evac_failure_scan_stack != NULL, "precondition");
4345
4346 while (_evac_failure_scan_stack->length() > 0) {
4347 oop obj = _evac_failure_scan_stack->pop();
4348 _evac_failure_closure->set_region(heap_region_containing(obj));
4349 obj->oop_iterate_backwards(_evac_failure_closure);
4350 }
4351 }
4352
4353 oop
4354 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4355 oop old) {
4356 assert(obj_in_cs(old),
4357 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4358 (HeapWord*) old));
4359 markOop m = old->mark();
4360 oop forward_ptr = old->forward_to_atomic(old);
4361 if (forward_ptr == NULL) {
4362 // Forward-to-self succeeded.
4363 assert(_par_scan_state != NULL, "par scan state");
4364 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4365 uint queue_num = _par_scan_state->queue_num();
4366
4367 _evacuation_failed = true;
4368 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4369 if (_evac_failure_closure != cl) {
4370 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4371 assert(!_drain_in_progress,
4372 "Should only be true while someone holds the lock.");
4373 // Set the global evac-failure closure to the current thread's.
4374 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4375 set_evac_failure_closure(cl);
4376 // Now do the common part.
4377 handle_evacuation_failure_common(old, m);
4378 // Reset to NULL.
4379 set_evac_failure_closure(NULL);
4380 } else {
4381 // The lock is already held, and this is recursive.
4382 assert(_drain_in_progress, "This should only be the recursive case.");
4383 handle_evacuation_failure_common(old, m);
4384 }
4385 return old;
4386 } else {
4387 // Forward-to-self failed. Either someone else managed to allocate
4388 // space for this object (old != forward_ptr) or they beat us in
4389 // self-forwarding it (old == forward_ptr).
4390 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4391 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4392 "should not be in the CSet",
4393 (HeapWord*) old, (HeapWord*) forward_ptr));
4394 return forward_ptr;
4395 }
4396 }
4397
4398 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4399 preserve_mark_if_necessary(old, m);
4400
4401 HeapRegion* r = heap_region_containing(old);
4402 if (!r->evacuation_failed()) {
4403 r->set_evacuation_failed(true);
4404 _hr_printer.evac_failure(r);
4405 }
4406
4407 push_on_evac_failure_scan_stack(old);
4408
4409 if (!_drain_in_progress) {
4410 // prevent recursion in copy_to_survivor_space()
4411 _drain_in_progress = true;
4412 drain_evac_failure_scan_stack();
4413 _drain_in_progress = false;
4414 }
4415 }
4416
4417 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4418 assert(evacuation_failed(), "Oversaving!");
4419 // We want to call the "for_promotion_failure" version only in the
4420 // case of a promotion failure.
4421 if (m->must_be_preserved_for_promotion_failure(obj)) {
4422 _objs_with_preserved_marks.push(obj);
4423 _preserved_marks_of_objs.push(m);
4424 }
4425 }
4426
4427 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4428 size_t word_size) {
4429 if (purpose == GCAllocForSurvived) {
4430 HeapWord* result = survivor_attempt_allocation(word_size);
4431 if (result != NULL) {
4432 return result;
4433 } else {
4434 // Let's try to allocate in the old gen in case we can fit the
4435 // object there.
4436 return old_attempt_allocation(word_size);
4437 }
4438 } else {
4439 assert(purpose == GCAllocForTenured, "sanity");
4440 HeapWord* result = old_attempt_allocation(word_size);
4441 if (result != NULL) {
4442 return result;
4443 } else {
4444 // Let's try to allocate in the survivors in case we can fit the
4445 // object there.
4446 return survivor_attempt_allocation(word_size);
4447 }
4448 }
4449
4450 ShouldNotReachHere();
4451 // Trying to keep some compilers happy.
4452 return NULL;
4453 }
4454
4455 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4456 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4457
4458 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4459 : _g1h(g1h),
4460 _refs(g1h->task_queue(queue_num)),
4461 _dcq(&g1h->dirty_card_queue_set()),
4462 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4463 _g1_rem(g1h->g1_rem_set()),
4464 _hash_seed(17), _queue_num(queue_num),
4465 _term_attempts(0),
4466 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4467 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4468 _age_table(false),
4469 _strong_roots_time(0), _term_time(0),
4470 _alloc_buffer_waste(0), _undo_waste(0) {
4471 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4472 // we "sacrifice" entry 0 to keep track of surviving bytes for
4473 // non-young regions (where the age is -1)
4474 // We also add a few elements at the beginning and at the end in
4475 // an attempt to eliminate cache contention
4476 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4477 uint array_length = PADDING_ELEM_NUM +
4478 real_length +
4479 PADDING_ELEM_NUM;
4480 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4481 if (_surviving_young_words_base == NULL)
4482 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4483 "Not enough space for young surv histo.");
4484 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4485 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4486
4487 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4488 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4489
4490 _start = os::elapsedTime();
4491 }
4492
4493 void
4494 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4495 {
4496 st->print_raw_cr("GC Termination Stats");
4497 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4498 " ------waste (KiB)------");
4499 st->print_raw_cr("thr ms ms % ms % attempts"
4500 " total alloc undo");
4501 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4502 " ------- ------- -------");
4503 }
4504
4505 void
4506 G1ParScanThreadState::print_termination_stats(int i,
4507 outputStream* const st) const
4508 {
4509 const double elapsed_ms = elapsed_time() * 1000.0;
4510 const double s_roots_ms = strong_roots_time() * 1000.0;
4511 const double term_ms = term_time() * 1000.0;
4512 st->print_cr("%3d %9.2f %9.2f %6.2f "
4513 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4514 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4515 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4516 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4517 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4518 alloc_buffer_waste() * HeapWordSize / K,
4519 undo_waste() * HeapWordSize / K);
4520 }
4521
4522 #ifdef ASSERT
4523 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4524 assert(ref != NULL, "invariant");
4525 assert(UseCompressedOops, "sanity");
4526 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4527 oop p = oopDesc::load_decode_heap_oop(ref);
4528 assert(_g1h->is_in_g1_reserved(p),
4529 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4530 return true;
4531 }
4532
4533 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4534 assert(ref != NULL, "invariant");
4535 if (has_partial_array_mask(ref)) {
4536 // Must be in the collection set--it's already been copied.
4537 oop p = clear_partial_array_mask(ref);
4538 assert(_g1h->obj_in_cs(p),
4539 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4540 } else {
4541 oop p = oopDesc::load_decode_heap_oop(ref);
4542 assert(_g1h->is_in_g1_reserved(p),
4543 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4544 }
4545 return true;
4546 }
4547
4548 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4549 if (ref.is_narrow()) {
4550 return verify_ref((narrowOop*) ref);
4551 } else {
4552 return verify_ref((oop*) ref);
4553 }
4554 }
4555 #endif // ASSERT
4556
4557 void G1ParScanThreadState::trim_queue() {
4558 assert(_evac_cl != NULL, "not set");
4559 assert(_evac_failure_cl != NULL, "not set");
4560 assert(_partial_scan_cl != NULL, "not set");
4561
4562 StarTask ref;
4563 do {
4564 // Drain the overflow stack first, so other threads can steal.
4565 while (refs()->pop_overflow(ref)) {
4566 deal_with_reference(ref);
4567 }
4568
4569 while (refs()->pop_local(ref)) {
4570 deal_with_reference(ref);
4571 }
4572 } while (!refs()->is_empty());
4573 }
4574
4575 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4576 G1ParScanThreadState* par_scan_state) :
4577 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4578 _par_scan_state(par_scan_state),
4579 _worker_id(par_scan_state->queue_num()),
4580 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4581 _mark_in_progress(_g1->mark_in_progress()) { }
4582
4583 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4584 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4585 #ifdef ASSERT
4586 HeapRegion* hr = _g1->heap_region_containing(obj);
4587 assert(hr != NULL, "sanity");
4588 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4589 #endif // ASSERT
4590
4591 // We know that the object is not moving so it's safe to read its size.
4592 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4593 }
4594
4595 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4596 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4597 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4598 #ifdef ASSERT
4599 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4600 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4601 assert(from_obj != to_obj, "should not be self-forwarded");
4602
4603 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4604 assert(from_hr != NULL, "sanity");
4605 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4606
4607 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4608 assert(to_hr != NULL, "sanity");
4609 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4610 #endif // ASSERT
4611
4612 // The object might be in the process of being copied by another
4613 // worker so we cannot trust that its to-space image is
4614 // well-formed. So we have to read its size from its from-space
4615 // image which we know should not be changing.
4616 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4617 }
4618
4619 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4620 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4621 ::copy_to_survivor_space(oop old) {
4622 size_t word_sz = old->size();
4623 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4624 // +1 to make the -1 indexes valid...
4625 int young_index = from_region->young_index_in_cset()+1;
4626 assert( (from_region->is_young() && young_index > 0) ||
4627 (!from_region->is_young() && young_index == 0), "invariant" );
4628 G1CollectorPolicy* g1p = _g1->g1_policy();
4629 markOop m = old->mark();
4630 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4631 : m->age();
4632 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4633 word_sz);
4634 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4635 #ifndef PRODUCT
4636 // Should this evacuation fail?
4637 if (_g1->evacuation_should_fail()) {
4638 if (obj_ptr != NULL) {
4639 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4640 obj_ptr = NULL;
4641 }
4642 }
4643 #endif // !PRODUCT
4644
4645 if (obj_ptr == NULL) {
4646 // This will either forward-to-self, or detect that someone else has
4647 // installed a forwarding pointer.
4648 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4649 }
4650
4651 oop obj = oop(obj_ptr);
4652
4653 // We're going to allocate linearly, so might as well prefetch ahead.
4654 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4655
4656 oop forward_ptr = old->forward_to_atomic(obj);
4657 if (forward_ptr == NULL) {
4658 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4659 if (g1p->track_object_age(alloc_purpose)) {
4660 // We could simply do obj->incr_age(). However, this causes a
4661 // performance issue. obj->incr_age() will first check whether
4662 // the object has a displaced mark by checking its mark word;
4663 // getting the mark word from the new location of the object
4664 // stalls. So, given that we already have the mark word and we
4665 // are about to install it anyway, it's better to increase the
4666 // age on the mark word, when the object does not have a
4667 // displaced mark word. We're not expecting many objects to have
4668 // a displaced marked word, so that case is not optimized
4669 // further (it could be...) and we simply call obj->incr_age().
4670
4671 if (m->has_displaced_mark_helper()) {
4672 // in this case, we have to install the mark word first,
4673 // otherwise obj looks to be forwarded (the old mark word,
4674 // which contains the forward pointer, was copied)
4675 obj->set_mark(m);
4676 obj->incr_age();
4677 } else {
4678 m = m->incr_age();
4679 obj->set_mark(m);
4680 }
4681 _par_scan_state->age_table()->add(obj, word_sz);
4682 } else {
4683 obj->set_mark(m);
4684 }
4685
4686 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4687 surv_young_words[young_index] += word_sz;
4688
4689 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4690 // We keep track of the next start index in the length field of
4691 // the to-space object. The actual length can be found in the
4692 // length field of the from-space object.
4693 arrayOop(obj)->set_length(0);
4694 oop* old_p = set_partial_array_mask(old);
4695 _par_scan_state->push_on_queue(old_p);
4696 } else {
4697 // No point in using the slower heap_region_containing() method,
4698 // given that we know obj is in the heap.
4699 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4700 obj->oop_iterate_backwards(&_scanner);
4701 }
4702 } else {
4703 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4704 obj = forward_ptr;
4705 }
4706 return obj;
4707 }
4708
4709 template <class T>
4710 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4711 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4712 _scanned_klass->record_modified_oops();
4713 }
4714 }
4715
4716 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4717 template <class T>
4718 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4719 ::do_oop_work(T* p) {
4720 oop obj = oopDesc::load_decode_heap_oop(p);
4721 assert(barrier != G1BarrierRS || obj != NULL,
4722 "Precondition: G1BarrierRS implies obj is non-NULL");
4723
4724 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4725
4726 // here the null check is implicit in the cset_fast_test() test
4727 if (_g1->in_cset_fast_test(obj)) {
4728 oop forwardee;
4729 if (obj->is_forwarded()) {
4730 forwardee = obj->forwardee();
4731 } else {
4732 forwardee = copy_to_survivor_space(obj);
4733 }
4734 assert(forwardee != NULL, "forwardee should not be NULL");
4735 oopDesc::encode_store_heap_oop(p, forwardee);
4736 if (do_mark_object && forwardee != obj) {
4737 // If the object is self-forwarded we don't need to explicitly
4738 // mark it, the evacuation failure protocol will do so.
4739 mark_forwarded_object(obj, forwardee);
4740 }
4741
4742 // When scanning the RS, we only care about objs in CS.
4743 if (barrier == G1BarrierRS) {
4744 _par_scan_state->update_rs(_from, p, _worker_id);
4745 } else if (barrier == G1BarrierKlass) {
4746 do_klass_barrier(p, forwardee);
4747 }
4748 } else {
4749 // The object is not in collection set. If we're a root scanning
4750 // closure during an initial mark pause (i.e. do_mark_object will
4751 // be true) then attempt to mark the object.
4752 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4753 mark_object(obj);
4754 }
4755 }
4756
4757 if (barrier == G1BarrierEvac && obj != NULL) {
4758 _par_scan_state->update_rs(_from, p, _worker_id);
4759 }
4760
4761 if (do_gen_barrier && obj != NULL) {
4762 par_do_barrier(p);
4763 }
4764 }
4765
4766 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4767 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4768
4769 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4770 assert(has_partial_array_mask(p), "invariant");
4771 oop from_obj = clear_partial_array_mask(p);
4772
4773 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4774 assert(from_obj->is_objArray(), "must be obj array");
4775 objArrayOop from_obj_array = objArrayOop(from_obj);
4776 // The from-space object contains the real length.
4777 int length = from_obj_array->length();
4778
4779 assert(from_obj->is_forwarded(), "must be forwarded");
4780 oop to_obj = from_obj->forwardee();
4781 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4782 objArrayOop to_obj_array = objArrayOop(to_obj);
4783 // We keep track of the next start index in the length field of the
4784 // to-space object.
4785 int next_index = to_obj_array->length();
4786 assert(0 <= next_index && next_index < length,
4787 err_msg("invariant, next index: %d, length: %d", next_index, length));
4788
4789 int start = next_index;
4790 int end = length;
4791 int remainder = end - start;
4792 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4793 if (remainder > 2 * ParGCArrayScanChunk) {
4794 end = start + ParGCArrayScanChunk;
4795 to_obj_array->set_length(end);
4796 // Push the remainder before we process the range in case another
4797 // worker has run out of things to do and can steal it.
4798 oop* from_obj_p = set_partial_array_mask(from_obj);
4799 _par_scan_state->push_on_queue(from_obj_p);
4800 } else {
4801 assert(length == end, "sanity");
4802 // We'll process the final range for this object. Restore the length
4803 // so that the heap remains parsable in case of evacuation failure.
4804 to_obj_array->set_length(end);
4805 }
4806 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4807 // Process indexes [start,end). It will also process the header
4808 // along with the first chunk (i.e., the chunk with start == 0).
4809 // Note that at this point the length field of to_obj_array is not
4810 // correct given that we are using it to keep track of the next
4811 // start index. oop_iterate_range() (thankfully!) ignores the length
4812 // field and only relies on the start / end parameters. It does
4813 // however return the size of the object which will be incorrect. So
4814 // we have to ignore it even if we wanted to use it.
4815 to_obj_array->oop_iterate_range(&_scanner, start, end);
4816 }
4817
4818 class G1ParEvacuateFollowersClosure : public VoidClosure {
4819 protected:
4820 G1CollectedHeap* _g1h;
4821 G1ParScanThreadState* _par_scan_state;
4822 RefToScanQueueSet* _queues;
4823 ParallelTaskTerminator* _terminator;
4824
4825 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4826 RefToScanQueueSet* queues() { return _queues; }
4827 ParallelTaskTerminator* terminator() { return _terminator; }
4828
4829 public:
4830 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4831 G1ParScanThreadState* par_scan_state,
4832 RefToScanQueueSet* queues,
4833 ParallelTaskTerminator* terminator)
4834 : _g1h(g1h), _par_scan_state(par_scan_state),
4835 _queues(queues), _terminator(terminator) {}
4836
4837 void do_void();
4838
4839 private:
4840 inline bool offer_termination();
4841 };
4842
4843 bool G1ParEvacuateFollowersClosure::offer_termination() {
4844 G1ParScanThreadState* const pss = par_scan_state();
4845 pss->start_term_time();
4846 const bool res = terminator()->offer_termination();
4847 pss->end_term_time();
4848 return res;
4849 }
4850
4851 void G1ParEvacuateFollowersClosure::do_void() {
4852 StarTask stolen_task;
4853 G1ParScanThreadState* const pss = par_scan_state();
4854 pss->trim_queue();
4855
4856 do {
4857 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4858 assert(pss->verify_task(stolen_task), "sanity");
4859 if (stolen_task.is_narrow()) {
4860 pss->deal_with_reference((narrowOop*) stolen_task);
4861 } else {
4862 pss->deal_with_reference((oop*) stolen_task);
4863 }
4864
4865 // We've just processed a reference and we might have made
4866 // available new entries on the queues. So we have to make sure
4867 // we drain the queues as necessary.
4868 pss->trim_queue();
4869 }
4870 } while (!offer_termination());
4871
4872 pss->retire_alloc_buffers();
4873 }
4874
4875 class G1KlassScanClosure : public KlassClosure {
4876 G1ParCopyHelper* _closure;
4877 bool _process_only_dirty;
4878 int _count;
4879 public:
4880 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4881 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4882 void do_klass(Klass* klass) {
4883 // If the klass has not been dirtied we know that there's
4884 // no references into the young gen and we can skip it.
4885 if (!_process_only_dirty || klass->has_modified_oops()) {
4886 // Clean the klass since we're going to scavenge all the metadata.
4887 klass->clear_modified_oops();
4888
4889 // Tell the closure that this klass is the Klass to scavenge
4890 // and is the one to dirty if oops are left pointing into the young gen.
4891 _closure->set_scanned_klass(klass);
4892
4893 klass->oops_do(_closure);
4894
4895 _closure->set_scanned_klass(NULL);
4896 }
4897 _count++;
4898 }
4899 };
4900
4901 class G1ParTask : public AbstractGangTask {
4902 protected:
4903 G1CollectedHeap* _g1h;
4904 RefToScanQueueSet *_queues;
4905 ParallelTaskTerminator _terminator;
4906 uint _n_workers;
4907
4908 Mutex _stats_lock;
4909 Mutex* stats_lock() { return &_stats_lock; }
4910
4911 size_t getNCards() {
4912 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4913 / G1BlockOffsetSharedArray::N_bytes;
4914 }
4915
4916 public:
4917 G1ParTask(G1CollectedHeap* g1h,
4918 RefToScanQueueSet *task_queues)
4919 : AbstractGangTask("G1 collection"),
4920 _g1h(g1h),
4921 _queues(task_queues),
4922 _terminator(0, _queues),
4923 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4924 {}
4925
4926 RefToScanQueueSet* queues() { return _queues; }
4927
4928 RefToScanQueue *work_queue(int i) {
4929 return queues()->queue(i);
4930 }
4931
4932 ParallelTaskTerminator* terminator() { return &_terminator; }
4933
4934 virtual void set_for_termination(int active_workers) {
4935 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4936 // in the young space (_par_seq_tasks) in the G1 heap
4937 // for SequentialSubTasksDone.
4938 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4939 // both of which need setting by set_n_termination().
4940 _g1h->SharedHeap::set_n_termination(active_workers);
4941 _g1h->set_n_termination(active_workers);
4942 terminator()->reset_for_reuse(active_workers);
4943 _n_workers = active_workers;
4944 }
4945
4946 void work(uint worker_id) {
4947 if (worker_id >= _n_workers) return; // no work needed this round
4948
4949 double start_time_ms = os::elapsedTime() * 1000.0;
4950 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4951
4952 {
4953 ResourceMark rm;
4954 HandleMark hm;
4955
4956 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4957
4958 G1ParScanThreadState pss(_g1h, worker_id);
4959 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4960 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4961 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4962
4963 pss.set_evac_closure(&scan_evac_cl);
4964 pss.set_evac_failure_closure(&evac_failure_cl);
4965 pss.set_partial_scan_closure(&partial_scan_cl);
4966
4967 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4968 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
4969
4970 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4971 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4972
4973 bool only_young = _g1h->g1_policy()->gcs_are_young();
4974 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4975 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4976
4977 OopClosure* scan_root_cl = &only_scan_root_cl;
4978 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
4979
4980 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4981 // We also need to mark copied objects.
4982 scan_root_cl = &scan_mark_root_cl;
4983 scan_klasses_cl = &scan_mark_klasses_cl_s;
4984 }
4985
4986 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4987
4988 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
4989
4990 pss.start_strong_roots();
4991 _g1h->g1_process_strong_roots(/* is scavenging */ true,
4992 SharedHeap::ScanningOption(so),
4993 scan_root_cl,
4994 &push_heap_rs_cl,
4995 scan_klasses_cl,
4996 worker_id);
4997 pss.end_strong_roots();
4998
4999 {
5000 double start = os::elapsedTime();
5001 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5002 evac.do_void();
5003 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5004 double term_ms = pss.term_time()*1000.0;
5005 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5006 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5007 }
5008 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5009 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5010
5011 if (ParallelGCVerbose) {
5012 MutexLocker x(stats_lock());
5013 pss.print_termination_stats(worker_id);
5014 }
5015
5016 assert(pss.refs()->is_empty(), "should be empty");
5017
5018 // Close the inner scope so that the ResourceMark and HandleMark
5019 // destructors are executed here and are included as part of the
5020 // "GC Worker Time".
5021 }
5022
5023 double end_time_ms = os::elapsedTime() * 1000.0;
5024 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5025 }
5026 };
5027
5028 // *** Common G1 Evacuation Stuff
5029
5030 // Closures that support the filtering of CodeBlobs scanned during
5031 // external root scanning.
5032
5033 // Closure applied to reference fields in code blobs (specifically nmethods)
5034 // to determine whether an nmethod contains references that point into
5035 // the collection set. Used as a predicate when walking code roots so
5036 // that only nmethods that point into the collection set are added to the
5037 // 'marked' list.
5038
5039 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
5040
5041 class G1PointsIntoCSOopClosure : public OopClosure {
5042 G1CollectedHeap* _g1;
5043 bool _points_into_cs;
5044 public:
5045 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
5046 _g1(g1), _points_into_cs(false) { }
5047
5048 bool points_into_cs() const { return _points_into_cs; }
5049
5050 template <class T>
5051 void do_oop_nv(T* p) {
5052 if (!_points_into_cs) {
5053 T heap_oop = oopDesc::load_heap_oop(p);
5054 if (!oopDesc::is_null(heap_oop) &&
5055 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
5056 _points_into_cs = true;
5057 }
5058 }
5059 }
5060
5061 virtual void do_oop(oop* p) { do_oop_nv(p); }
5062 virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
5063 };
5064
5065 G1CollectedHeap* _g1;
5066
5067 public:
5068 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
5069 CodeBlobToOopClosure(cl, true), _g1(g1) { }
5070
5071 virtual void do_code_blob(CodeBlob* cb) {
5072 nmethod* nm = cb->as_nmethod_or_null();
5073 if (nm != NULL && !(nm->test_oops_do_mark())) {
5074 G1PointsIntoCSOopClosure predicate_cl(_g1);
5075 nm->oops_do(&predicate_cl);
5076
5077 if (predicate_cl.points_into_cs()) {
5078 // At least one of the reference fields or the oop relocations
5079 // in the nmethod points into the collection set. We have to
5080 // 'mark' this nmethod.
5081 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
5082 // or MarkingCodeBlobClosure::do_code_blob() change.
5083 if (!nm->test_set_oops_do_mark()) {
5084 do_newly_marked_nmethod(nm);
5085 }
5086 }
5087 }
5088 }
5089 };
5090
5091 // This method is run in a GC worker.
5092
5093 void
5094 G1CollectedHeap::
5095 g1_process_strong_roots(bool is_scavenging,
5096 ScanningOption so,
5097 OopClosure* scan_non_heap_roots,
5098 OopsInHeapRegionClosure* scan_rs,
5099 G1KlassScanClosure* scan_klasses,
5100 int worker_i) {
5101
5102 // First scan the strong roots
5103 double ext_roots_start = os::elapsedTime();
5104 double closure_app_time_sec = 0.0;
5105
5106 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5107
5108 // Walk the code cache w/o buffering, because StarTask cannot handle
5109 // unaligned oop locations.
5110 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5111
5112 process_strong_roots(false, // no scoping; this is parallel code
5113 is_scavenging, so,
5114 &buf_scan_non_heap_roots,
5115 &eager_scan_code_roots,
5116 scan_klasses
5117 );
5118
5119 // Now the CM ref_processor roots.
5120 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5121 // We need to treat the discovered reference lists of the
5122 // concurrent mark ref processor as roots and keep entries
5123 // (which are added by the marking threads) on them live
5124 // until they can be processed at the end of marking.
5125 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5126 }
5127
5128 // Finish up any enqueued closure apps (attributed as object copy time).
5129 buf_scan_non_heap_roots.done();
5130
5131 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5132
5133 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5134
5135 double ext_root_time_ms =
5136 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5137
5138 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5139
5140 // During conc marking we have to filter the per-thread SATB buffers
5141 // to make sure we remove any oops into the CSet (which will show up
5142 // as implicitly live).
5143 double satb_filtering_ms = 0.0;
5144 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5145 if (mark_in_progress()) {
5146 double satb_filter_start = os::elapsedTime();
5147
5148 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5149
5150 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5151 }
5152 }
5153 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5154
5155 // Now scan the complement of the collection set.
5156 if (scan_rs != NULL) {
5157 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5158 }
5159 _process_strong_tasks->all_tasks_completed();
5160 }
5161
5162 void
5163 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5164 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5165 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5166 }
5167
5168 // Weak Reference Processing support
5169
5170 // An always "is_alive" closure that is used to preserve referents.
5171 // If the object is non-null then it's alive. Used in the preservation
5172 // of referent objects that are pointed to by reference objects
5173 // discovered by the CM ref processor.
5174 class G1AlwaysAliveClosure: public BoolObjectClosure {
5175 G1CollectedHeap* _g1;
5176 public:
5177 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5178 bool do_object_b(oop p) {
5179 if (p != NULL) {
5180 return true;
5181 }
5182 return false;
5183 }
5184 };
5185
5186 bool G1STWIsAliveClosure::do_object_b(oop p) {
5187 // An object is reachable if it is outside the collection set,
5188 // or is inside and copied.
5189 return !_g1->obj_in_cs(p) || p->is_forwarded();
5190 }
5191
5192 // Non Copying Keep Alive closure
5193 class G1KeepAliveClosure: public OopClosure {
5194 G1CollectedHeap* _g1;
5195 public:
5196 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5197 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5198 void do_oop( oop* p) {
5199 oop obj = *p;
5200
5201 if (_g1->obj_in_cs(obj)) {
5202 assert( obj->is_forwarded(), "invariant" );
5203 *p = obj->forwardee();
5204 }
5205 }
5206 };
5207
5208 // Copying Keep Alive closure - can be called from both
5209 // serial and parallel code as long as different worker
5210 // threads utilize different G1ParScanThreadState instances
5211 // and different queues.
5212
5213 class G1CopyingKeepAliveClosure: public OopClosure {
5214 G1CollectedHeap* _g1h;
5215 OopClosure* _copy_non_heap_obj_cl;
5216 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5217 G1ParScanThreadState* _par_scan_state;
5218
5219 public:
5220 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5221 OopClosure* non_heap_obj_cl,
5222 OopsInHeapRegionClosure* metadata_obj_cl,
5223 G1ParScanThreadState* pss):
5224 _g1h(g1h),
5225 _copy_non_heap_obj_cl(non_heap_obj_cl),
5226 _copy_metadata_obj_cl(metadata_obj_cl),
5227 _par_scan_state(pss)
5228 {}
5229
5230 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5231 virtual void do_oop( oop* p) { do_oop_work(p); }
5232
5233 template <class T> void do_oop_work(T* p) {
5234 oop obj = oopDesc::load_decode_heap_oop(p);
5235
5236 if (_g1h->obj_in_cs(obj)) {
5237 // If the referent object has been forwarded (either copied
5238 // to a new location or to itself in the event of an
5239 // evacuation failure) then we need to update the reference
5240 // field and, if both reference and referent are in the G1
5241 // heap, update the RSet for the referent.
5242 //
5243 // If the referent has not been forwarded then we have to keep
5244 // it alive by policy. Therefore we have copy the referent.
5245 //
5246 // If the reference field is in the G1 heap then we can push
5247 // on the PSS queue. When the queue is drained (after each
5248 // phase of reference processing) the object and it's followers
5249 // will be copied, the reference field set to point to the
5250 // new location, and the RSet updated. Otherwise we need to
5251 // use the the non-heap or metadata closures directly to copy
5252 // the referent object and update the pointer, while avoiding
5253 // updating the RSet.
5254
5255 if (_g1h->is_in_g1_reserved(p)) {
5256 _par_scan_state->push_on_queue(p);
5257 } else {
5258 assert(!ClassLoaderDataGraph::contains((address)p),
5259 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5260 PTR_FORMAT, p));
5261 _copy_non_heap_obj_cl->do_oop(p);
5262 }
5263 }
5264 }
5265 };
5266
5267 // Serial drain queue closure. Called as the 'complete_gc'
5268 // closure for each discovered list in some of the
5269 // reference processing phases.
5270
5271 class G1STWDrainQueueClosure: public VoidClosure {
5272 protected:
5273 G1CollectedHeap* _g1h;
5274 G1ParScanThreadState* _par_scan_state;
5275
5276 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5277
5278 public:
5279 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5280 _g1h(g1h),
5281 _par_scan_state(pss)
5282 { }
5283
5284 void do_void() {
5285 G1ParScanThreadState* const pss = par_scan_state();
5286 pss->trim_queue();
5287 }
5288 };
5289
5290 // Parallel Reference Processing closures
5291
5292 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5293 // processing during G1 evacuation pauses.
5294
5295 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5296 private:
5297 G1CollectedHeap* _g1h;
5298 RefToScanQueueSet* _queues;
5299 FlexibleWorkGang* _workers;
5300 int _active_workers;
5301
5302 public:
5303 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5304 FlexibleWorkGang* workers,
5305 RefToScanQueueSet *task_queues,
5306 int n_workers) :
5307 _g1h(g1h),
5308 _queues(task_queues),
5309 _workers(workers),
5310 _active_workers(n_workers)
5311 {
5312 assert(n_workers > 0, "shouldn't call this otherwise");
5313 }
5314
5315 // Executes the given task using concurrent marking worker threads.
5316 virtual void execute(ProcessTask& task);
5317 virtual void execute(EnqueueTask& task);
5318 };
5319
5320 // Gang task for possibly parallel reference processing
5321
5322 class G1STWRefProcTaskProxy: public AbstractGangTask {
5323 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5324 ProcessTask& _proc_task;
5325 G1CollectedHeap* _g1h;
5326 RefToScanQueueSet *_task_queues;
5327 ParallelTaskTerminator* _terminator;
5328
5329 public:
5330 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5331 G1CollectedHeap* g1h,
5332 RefToScanQueueSet *task_queues,
5333 ParallelTaskTerminator* terminator) :
5334 AbstractGangTask("Process reference objects in parallel"),
5335 _proc_task(proc_task),
5336 _g1h(g1h),
5337 _task_queues(task_queues),
5338 _terminator(terminator)
5339 {}
5340
5341 virtual void work(uint worker_id) {
5342 // The reference processing task executed by a single worker.
5343 ResourceMark rm;
5344 HandleMark hm;
5345
5346 G1STWIsAliveClosure is_alive(_g1h);
5347
5348 G1ParScanThreadState pss(_g1h, worker_id);
5349
5350 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5351 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5352 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5353
5354 pss.set_evac_closure(&scan_evac_cl);
5355 pss.set_evac_failure_closure(&evac_failure_cl);
5356 pss.set_partial_scan_closure(&partial_scan_cl);
5357
5358 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5359 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5360
5361 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5362 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5363
5364 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5365 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5366
5367 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5368 // We also need to mark copied objects.
5369 copy_non_heap_cl = ©_mark_non_heap_cl;
5370 copy_metadata_cl = ©_mark_metadata_cl;
5371 }
5372
5373 // Keep alive closure.
5374 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5375
5376 // Complete GC closure
5377 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5378
5379 // Call the reference processing task's work routine.
5380 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5381
5382 // Note we cannot assert that the refs array is empty here as not all
5383 // of the processing tasks (specifically phase2 - pp2_work) execute
5384 // the complete_gc closure (which ordinarily would drain the queue) so
5385 // the queue may not be empty.
5386 }
5387 };
5388
5389 // Driver routine for parallel reference processing.
5390 // Creates an instance of the ref processing gang
5391 // task and has the worker threads execute it.
5392 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5393 assert(_workers != NULL, "Need parallel worker threads.");
5394
5395 ParallelTaskTerminator terminator(_active_workers, _queues);
5396 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5397
5398 _g1h->set_par_threads(_active_workers);
5399 _workers->run_task(&proc_task_proxy);
5400 _g1h->set_par_threads(0);
5401 }
5402
5403 // Gang task for parallel reference enqueueing.
5404
5405 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5406 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5407 EnqueueTask& _enq_task;
5408
5409 public:
5410 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5411 AbstractGangTask("Enqueue reference objects in parallel"),
5412 _enq_task(enq_task)
5413 { }
5414
5415 virtual void work(uint worker_id) {
5416 _enq_task.work(worker_id);
5417 }
5418 };
5419
5420 // Driver routine for parallel reference enqueueing.
5421 // Creates an instance of the ref enqueueing gang
5422 // task and has the worker threads execute it.
5423
5424 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5425 assert(_workers != NULL, "Need parallel worker threads.");
5426
5427 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5428
5429 _g1h->set_par_threads(_active_workers);
5430 _workers->run_task(&enq_task_proxy);
5431 _g1h->set_par_threads(0);
5432 }
5433
5434 // End of weak reference support closures
5435
5436 // Abstract task used to preserve (i.e. copy) any referent objects
5437 // that are in the collection set and are pointed to by reference
5438 // objects discovered by the CM ref processor.
5439
5440 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5441 protected:
5442 G1CollectedHeap* _g1h;
5443 RefToScanQueueSet *_queues;
5444 ParallelTaskTerminator _terminator;
5445 uint _n_workers;
5446
5447 public:
5448 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5449 AbstractGangTask("ParPreserveCMReferents"),
5450 _g1h(g1h),
5451 _queues(task_queues),
5452 _terminator(workers, _queues),
5453 _n_workers(workers)
5454 { }
5455
5456 void work(uint worker_id) {
5457 ResourceMark rm;
5458 HandleMark hm;
5459
5460 G1ParScanThreadState pss(_g1h, worker_id);
5461 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5462 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5463 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5464
5465 pss.set_evac_closure(&scan_evac_cl);
5466 pss.set_evac_failure_closure(&evac_failure_cl);
5467 pss.set_partial_scan_closure(&partial_scan_cl);
5468
5469 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5470
5471
5472 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5473 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5474
5475 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5476 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5477
5478 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5479 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5480
5481 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5482 // We also need to mark copied objects.
5483 copy_non_heap_cl = ©_mark_non_heap_cl;
5484 copy_metadata_cl = ©_mark_metadata_cl;
5485 }
5486
5487 // Is alive closure
5488 G1AlwaysAliveClosure always_alive(_g1h);
5489
5490 // Copying keep alive closure. Applied to referent objects that need
5491 // to be copied.
5492 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5493
5494 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5495
5496 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5497 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5498
5499 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5500 // So this must be true - but assert just in case someone decides to
5501 // change the worker ids.
5502 assert(0 <= worker_id && worker_id < limit, "sanity");
5503 assert(!rp->discovery_is_atomic(), "check this code");
5504
5505 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5506 for (uint idx = worker_id; idx < limit; idx += stride) {
5507 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5508
5509 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5510 while (iter.has_next()) {
5511 // Since discovery is not atomic for the CM ref processor, we
5512 // can see some null referent objects.
5513 iter.load_ptrs(DEBUG_ONLY(true));
5514 oop ref = iter.obj();
5515
5516 // This will filter nulls.
5517 if (iter.is_referent_alive()) {
5518 iter.make_referent_alive();
5519 }
5520 iter.move_to_next();
5521 }
5522 }
5523
5524 // Drain the queue - which may cause stealing
5525 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5526 drain_queue.do_void();
5527 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5528 assert(pss.refs()->is_empty(), "should be");
5529 }
5530 };
5531
5532 // Weak Reference processing during an evacuation pause (part 1).
5533 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5534 double ref_proc_start = os::elapsedTime();
5535
5536 ReferenceProcessor* rp = _ref_processor_stw;
5537 assert(rp->discovery_enabled(), "should have been enabled");
5538
5539 // Any reference objects, in the collection set, that were 'discovered'
5540 // by the CM ref processor should have already been copied (either by
5541 // applying the external root copy closure to the discovered lists, or
5542 // by following an RSet entry).
5543 //
5544 // But some of the referents, that are in the collection set, that these
5545 // reference objects point to may not have been copied: the STW ref
5546 // processor would have seen that the reference object had already
5547 // been 'discovered' and would have skipped discovering the reference,
5548 // but would not have treated the reference object as a regular oop.
5549 // As a result the copy closure would not have been applied to the
5550 // referent object.
5551 //
5552 // We need to explicitly copy these referent objects - the references
5553 // will be processed at the end of remarking.
5554 //
5555 // We also need to do this copying before we process the reference
5556 // objects discovered by the STW ref processor in case one of these
5557 // referents points to another object which is also referenced by an
5558 // object discovered by the STW ref processor.
5559
5560 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5561 no_of_gc_workers == workers()->active_workers(),
5562 "Need to reset active GC workers");
5563
5564 set_par_threads(no_of_gc_workers);
5565 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5566 no_of_gc_workers,
5567 _task_queues);
5568
5569 if (G1CollectedHeap::use_parallel_gc_threads()) {
5570 workers()->run_task(&keep_cm_referents);
5571 } else {
5572 keep_cm_referents.work(0);
5573 }
5574
5575 set_par_threads(0);
5576
5577 // Closure to test whether a referent is alive.
5578 G1STWIsAliveClosure is_alive(this);
5579
5580 // Even when parallel reference processing is enabled, the processing
5581 // of JNI refs is serial and performed serially by the current thread
5582 // rather than by a worker. The following PSS will be used for processing
5583 // JNI refs.
5584
5585 // Use only a single queue for this PSS.
5586 G1ParScanThreadState pss(this, 0);
5587
5588 // We do not embed a reference processor in the copying/scanning
5589 // closures while we're actually processing the discovered
5590 // reference objects.
5591 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5592 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5593 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5594
5595 pss.set_evac_closure(&scan_evac_cl);
5596 pss.set_evac_failure_closure(&evac_failure_cl);
5597 pss.set_partial_scan_closure(&partial_scan_cl);
5598
5599 assert(pss.refs()->is_empty(), "pre-condition");
5600
5601 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5602 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5603
5604 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5605 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5606
5607 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5608 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5609
5610 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5611 // We also need to mark copied objects.
5612 copy_non_heap_cl = ©_mark_non_heap_cl;
5613 copy_metadata_cl = ©_mark_metadata_cl;
5614 }
5615
5616 // Keep alive closure.
5617 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5618
5619 // Serial Complete GC closure
5620 G1STWDrainQueueClosure drain_queue(this, &pss);
5621
5622 // Setup the soft refs policy...
5623 rp->setup_policy(false);
5624
5625 ReferenceProcessorStats stats;
5626 if (!rp->processing_is_mt()) {
5627 // Serial reference processing...
5628 stats = rp->process_discovered_references(&is_alive,
5629 &keep_alive,
5630 &drain_queue,
5631 NULL,
5632 _gc_timer_stw);
5633 } else {
5634 // Parallel reference processing
5635 assert(rp->num_q() == no_of_gc_workers, "sanity");
5636 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5637
5638 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5639 stats = rp->process_discovered_references(&is_alive,
5640 &keep_alive,
5641 &drain_queue,
5642 &par_task_executor,
5643 _gc_timer_stw);
5644 }
5645
5646 _gc_tracer_stw->report_gc_reference_stats(stats);
5647 // We have completed copying any necessary live referent objects
5648 // (that were not copied during the actual pause) so we can
5649 // retire any active alloc buffers
5650 pss.retire_alloc_buffers();
5651 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5652
5653 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5654 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5655 }
5656
5657 // Weak Reference processing during an evacuation pause (part 2).
5658 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5659 double ref_enq_start = os::elapsedTime();
5660
5661 ReferenceProcessor* rp = _ref_processor_stw;
5662 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5663
5664 // Now enqueue any remaining on the discovered lists on to
5665 // the pending list.
5666 if (!rp->processing_is_mt()) {
5667 // Serial reference processing...
5668 rp->enqueue_discovered_references();
5669 } else {
5670 // Parallel reference enqueueing
5671
5672 assert(no_of_gc_workers == workers()->active_workers(),
5673 "Need to reset active workers");
5674 assert(rp->num_q() == no_of_gc_workers, "sanity");
5675 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5676
5677 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5678 rp->enqueue_discovered_references(&par_task_executor);
5679 }
5680
5681 rp->verify_no_references_recorded();
5682 assert(!rp->discovery_enabled(), "should have been disabled");
5683
5684 // FIXME
5685 // CM's reference processing also cleans up the string and symbol tables.
5686 // Should we do that here also? We could, but it is a serial operation
5687 // and could significantly increase the pause time.
5688
5689 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5690 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5691 }
5692
5693 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5694 _expand_heap_after_alloc_failure = true;
5695 _evacuation_failed = false;
5696
5697 // Should G1EvacuationFailureALot be in effect for this GC?
5698 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5699
5700 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5701
5702 // Disable the hot card cache.
5703 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5704 hot_card_cache->reset_hot_cache_claimed_index();
5705 hot_card_cache->set_use_cache(false);
5706
5707 uint n_workers;
5708 if (G1CollectedHeap::use_parallel_gc_threads()) {
5709 n_workers =
5710 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5711 workers()->active_workers(),
5712 Threads::number_of_non_daemon_threads());
5713 assert(UseDynamicNumberOfGCThreads ||
5714 n_workers == workers()->total_workers(),
5715 "If not dynamic should be using all the workers");
5716 workers()->set_active_workers(n_workers);
5717 set_par_threads(n_workers);
5718 } else {
5719 assert(n_par_threads() == 0,
5720 "Should be the original non-parallel value");
5721 n_workers = 1;
5722 }
5723
5724 G1ParTask g1_par_task(this, _task_queues);
5725
5726 init_for_evac_failure(NULL);
5727
5728 rem_set()->prepare_for_younger_refs_iterate(true);
5729
5730 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5731 double start_par_time_sec = os::elapsedTime();
5732 double end_par_time_sec;
5733
5734 {
5735 StrongRootsScope srs(this);
5736
5737 if (G1CollectedHeap::use_parallel_gc_threads()) {
5738 // The individual threads will set their evac-failure closures.
5739 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5740 // These tasks use ShareHeap::_process_strong_tasks
5741 assert(UseDynamicNumberOfGCThreads ||
5742 workers()->active_workers() == workers()->total_workers(),
5743 "If not dynamic should be using all the workers");
5744 workers()->run_task(&g1_par_task);
5745 } else {
5746 g1_par_task.set_for_termination(n_workers);
5747 g1_par_task.work(0);
5748 }
5749 end_par_time_sec = os::elapsedTime();
5750
5751 // Closing the inner scope will execute the destructor
5752 // for the StrongRootsScope object. We record the current
5753 // elapsed time before closing the scope so that time
5754 // taken for the SRS destructor is NOT included in the
5755 // reported parallel time.
5756 }
5757
5758 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5759 g1_policy()->phase_times()->record_par_time(par_time_ms);
5760
5761 double code_root_fixup_time_ms =
5762 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5763 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5764
5765 set_par_threads(0);
5766
5767 // Process any discovered reference objects - we have
5768 // to do this _before_ we retire the GC alloc regions
5769 // as we may have to copy some 'reachable' referent
5770 // objects (and their reachable sub-graphs) that were
5771 // not copied during the pause.
5772 process_discovered_references(n_workers);
5773
5774 // Weak root processing.
5775 // Note: when JSR 292 is enabled and code blobs can contain
5776 // non-perm oops then we will need to process the code blobs
5777 // here too.
5778 {
5779 G1STWIsAliveClosure is_alive(this);
5780 G1KeepAliveClosure keep_alive(this);
5781 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5782 }
5783
5784 release_gc_alloc_regions(n_workers, evacuation_info);
5785 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5786
5787 // Reset and re-enable the hot card cache.
5788 // Note the counts for the cards in the regions in the
5789 // collection set are reset when the collection set is freed.
5790 hot_card_cache->reset_hot_cache();
5791 hot_card_cache->set_use_cache(true);
5792
5793 finalize_for_evac_failure();
5794
5795 if (evacuation_failed()) {
5796 remove_self_forwarding_pointers();
5797
5798 // Reset the G1EvacuationFailureALot counters and flags
5799 // Note: the values are reset only when an actual
5800 // evacuation failure occurs.
5801 NOT_PRODUCT(reset_evacuation_should_fail();)
5802 }
5803
5804 // Enqueue any remaining references remaining on the STW
5805 // reference processor's discovered lists. We need to do
5806 // this after the card table is cleaned (and verified) as
5807 // the act of enqueueing entries on to the pending list
5808 // will log these updates (and dirty their associated
5809 // cards). We need these updates logged to update any
5810 // RSets.
5811 enqueue_discovered_references(n_workers);
5812
5813 if (G1DeferredRSUpdate) {
5814 RedirtyLoggedCardTableEntryFastClosure redirty;
5815 dirty_card_queue_set().set_closure(&redirty);
5816 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5817
5818 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5819 dcq.merge_bufferlists(&dirty_card_queue_set());
5820 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5821 }
5822 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5823 }
5824
5825 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5826 size_t* pre_used,
5827 FreeRegionList* free_list,
5828 OldRegionSet* old_proxy_set,
5829 HumongousRegionSet* humongous_proxy_set,
5830 HRRSCleanupTask* hrrs_cleanup_task,
5831 bool par) {
5832 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5833 if (hr->isHumongous()) {
5834 assert(hr->startsHumongous(), "we should only see starts humongous");
5835 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5836 } else {
5837 _old_set.remove_with_proxy(hr, old_proxy_set);
5838 free_region(hr, pre_used, free_list, par);
5839 }
5840 } else {
5841 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5842 }
5843 }
5844
5845 void G1CollectedHeap::free_region(HeapRegion* hr,
5846 size_t* pre_used,
5847 FreeRegionList* free_list,
5848 bool par) {
5849 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5850 assert(!hr->is_empty(), "the region should not be empty");
5851 assert(free_list != NULL, "pre-condition");
5852
5853 // Clear the card counts for this region.
5854 // Note: we only need to do this if the region is not young
5855 // (since we don't refine cards in young regions).
5856 if (!hr->is_young()) {
5857 _cg1r->hot_card_cache()->reset_card_counts(hr);
5858 }
5859 *pre_used += hr->used();
5860 hr->hr_clear(par, true /* clear_space */);
5861 free_list->add_as_head(hr);
5862 }
5863
5864 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5865 size_t* pre_used,
5866 FreeRegionList* free_list,
5867 HumongousRegionSet* humongous_proxy_set,
5868 bool par) {
5869 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5870 assert(free_list != NULL, "pre-condition");
5871 assert(humongous_proxy_set != NULL, "pre-condition");
5872
5873 size_t hr_used = hr->used();
5874 size_t hr_capacity = hr->capacity();
5875 size_t hr_pre_used = 0;
5876 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5877 // We need to read this before we make the region non-humongous,
5878 // otherwise the information will be gone.
5879 uint last_index = hr->last_hc_index();
5880 hr->set_notHumongous();
5881 free_region(hr, &hr_pre_used, free_list, par);
5882
5883 uint i = hr->hrs_index() + 1;
5884 while (i < last_index) {
5885 HeapRegion* curr_hr = region_at(i);
5886 assert(curr_hr->continuesHumongous(), "invariant");
5887 curr_hr->set_notHumongous();
5888 free_region(curr_hr, &hr_pre_used, free_list, par);
5889 i += 1;
5890 }
5891 assert(hr_pre_used == hr_used,
5892 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5893 "should be the same", hr_pre_used, hr_used));
5894 *pre_used += hr_pre_used;
5895 }
5896
5897 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5898 FreeRegionList* free_list,
5899 OldRegionSet* old_proxy_set,
5900 HumongousRegionSet* humongous_proxy_set,
5901 bool par) {
5902 if (pre_used > 0) {
5903 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5904 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5905 assert(_summary_bytes_used >= pre_used,
5906 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5907 "should be >= pre_used: "SIZE_FORMAT,
5908 _summary_bytes_used, pre_used));
5909 _summary_bytes_used -= pre_used;
5910 }
5911 if (free_list != NULL && !free_list->is_empty()) {
5912 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5913 _free_list.add_as_head(free_list);
5914 }
5915 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5916 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5917 _old_set.update_from_proxy(old_proxy_set);
5918 }
5919 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5920 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5921 _humongous_set.update_from_proxy(humongous_proxy_set);
5922 }
5923 }
5924
5925 class G1ParCleanupCTTask : public AbstractGangTask {
5926 CardTableModRefBS* _ct_bs;
5927 G1CollectedHeap* _g1h;
5928 HeapRegion* volatile _su_head;
5929 public:
5930 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5931 G1CollectedHeap* g1h) :
5932 AbstractGangTask("G1 Par Cleanup CT Task"),
5933 _ct_bs(ct_bs), _g1h(g1h) { }
5934
5935 void work(uint worker_id) {
5936 HeapRegion* r;
5937 while (r = _g1h->pop_dirty_cards_region()) {
5938 clear_cards(r);
5939 }
5940 }
5941
5942 void clear_cards(HeapRegion* r) {
5943 // Cards of the survivors should have already been dirtied.
5944 if (!r->is_survivor()) {
5945 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5946 }
5947 }
5948 };
5949
5950 #ifndef PRODUCT
5951 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5952 G1CollectedHeap* _g1h;
5953 CardTableModRefBS* _ct_bs;
5954 public:
5955 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5956 : _g1h(g1h), _ct_bs(ct_bs) { }
5957 virtual bool doHeapRegion(HeapRegion* r) {
5958 if (r->is_survivor()) {
5959 _g1h->verify_dirty_region(r);
5960 } else {
5961 _g1h->verify_not_dirty_region(r);
5962 }
5963 return false;
5964 }
5965 };
5966
5967 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5968 // All of the region should be clean.
5969 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5970 MemRegion mr(hr->bottom(), hr->end());
5971 ct_bs->verify_not_dirty_region(mr);
5972 }
5973
5974 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5975 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5976 // dirty allocated blocks as they allocate them. The thread that
5977 // retires each region and replaces it with a new one will do a
5978 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5979 // not dirty that area (one less thing to have to do while holding
5980 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5981 // is dirty.
5982 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5983 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5984 ct_bs->verify_dirty_region(mr);
5985 }
5986
5987 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5988 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5989 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5990 verify_dirty_region(hr);
5991 }
5992 }
5993
5994 void G1CollectedHeap::verify_dirty_young_regions() {
5995 verify_dirty_young_list(_young_list->first_region());
5996 }
5997 #endif
5998
5999 void G1CollectedHeap::cleanUpCardTable() {
6000 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
6001 double start = os::elapsedTime();
6002
6003 {
6004 // Iterate over the dirty cards region list.
6005 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6006
6007 if (G1CollectedHeap::use_parallel_gc_threads()) {
6008 set_par_threads();
6009 workers()->run_task(&cleanup_task);
6010 set_par_threads(0);
6011 } else {
6012 while (_dirty_cards_region_list) {
6013 HeapRegion* r = _dirty_cards_region_list;
6014 cleanup_task.clear_cards(r);
6015 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6016 if (_dirty_cards_region_list == r) {
6017 // The last region.
6018 _dirty_cards_region_list = NULL;
6019 }
6020 r->set_next_dirty_cards_region(NULL);
6021 }
6022 }
6023 #ifndef PRODUCT
6024 if (G1VerifyCTCleanup || VerifyAfterGC) {
6025 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6026 heap_region_iterate(&cleanup_verifier);
6027 }
6028 #endif
6029 }
6030
6031 double elapsed = os::elapsedTime() - start;
6032 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6033 }
6034
6035 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6036 size_t pre_used = 0;
6037 FreeRegionList local_free_list("Local List for CSet Freeing");
6038
6039 double young_time_ms = 0.0;
6040 double non_young_time_ms = 0.0;
6041
6042 // Since the collection set is a superset of the the young list,
6043 // all we need to do to clear the young list is clear its
6044 // head and length, and unlink any young regions in the code below
6045 _young_list->clear();
6046
6047 G1CollectorPolicy* policy = g1_policy();
6048
6049 double start_sec = os::elapsedTime();
6050 bool non_young = true;
6051
6052 HeapRegion* cur = cs_head;
6053 int age_bound = -1;
6054 size_t rs_lengths = 0;
6055
6056 while (cur != NULL) {
6057 assert(!is_on_master_free_list(cur), "sanity");
6058 if (non_young) {
6059 if (cur->is_young()) {
6060 double end_sec = os::elapsedTime();
6061 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6062 non_young_time_ms += elapsed_ms;
6063
6064 start_sec = os::elapsedTime();
6065 non_young = false;
6066 }
6067 } else {
6068 if (!cur->is_young()) {
6069 double end_sec = os::elapsedTime();
6070 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6071 young_time_ms += elapsed_ms;
6072
6073 start_sec = os::elapsedTime();
6074 non_young = true;
6075 }
6076 }
6077
6078 rs_lengths += cur->rem_set()->occupied();
6079
6080 HeapRegion* next = cur->next_in_collection_set();
6081 assert(cur->in_collection_set(), "bad CS");
6082 cur->set_next_in_collection_set(NULL);
6083 cur->set_in_collection_set(false);
6084
6085 if (cur->is_young()) {
6086 int index = cur->young_index_in_cset();
6087 assert(index != -1, "invariant");
6088 assert((uint) index < policy->young_cset_region_length(), "invariant");
6089 size_t words_survived = _surviving_young_words[index];
6090 cur->record_surv_words_in_group(words_survived);
6091
6092 // At this point the we have 'popped' cur from the collection set
6093 // (linked via next_in_collection_set()) but it is still in the
6094 // young list (linked via next_young_region()). Clear the
6095 // _next_young_region field.
6096 cur->set_next_young_region(NULL);
6097 } else {
6098 int index = cur->young_index_in_cset();
6099 assert(index == -1, "invariant");
6100 }
6101
6102 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6103 (!cur->is_young() && cur->young_index_in_cset() == -1),
6104 "invariant" );
6105
6106 if (!cur->evacuation_failed()) {
6107 MemRegion used_mr = cur->used_region();
6108
6109 // And the region is empty.
6110 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6111 free_region(cur, &pre_used, &local_free_list, false /* par */);
6112 } else {
6113 cur->uninstall_surv_rate_group();
6114 if (cur->is_young()) {
6115 cur->set_young_index_in_cset(-1);
6116 }
6117 cur->set_not_young();
6118 cur->set_evacuation_failed(false);
6119 // The region is now considered to be old.
6120 _old_set.add(cur);
6121 evacuation_info.increment_collectionset_used_after(cur->used());
6122 }
6123 cur = next;
6124 }
6125
6126 evacuation_info.set_regions_freed(local_free_list.length());
6127 policy->record_max_rs_lengths(rs_lengths);
6128 policy->cset_regions_freed();
6129
6130 double end_sec = os::elapsedTime();
6131 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6132
6133 if (non_young) {
6134 non_young_time_ms += elapsed_ms;
6135 } else {
6136 young_time_ms += elapsed_ms;
6137 }
6138
6139 update_sets_after_freeing_regions(pre_used, &local_free_list,
6140 NULL /* old_proxy_set */,
6141 NULL /* humongous_proxy_set */,
6142 false /* par */);
6143 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6144 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6145 }
6146
6147 // This routine is similar to the above but does not record
6148 // any policy statistics or update free lists; we are abandoning
6149 // the current incremental collection set in preparation of a
6150 // full collection. After the full GC we will start to build up
6151 // the incremental collection set again.
6152 // This is only called when we're doing a full collection
6153 // and is immediately followed by the tearing down of the young list.
6154
6155 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6156 HeapRegion* cur = cs_head;
6157
6158 while (cur != NULL) {
6159 HeapRegion* next = cur->next_in_collection_set();
6160 assert(cur->in_collection_set(), "bad CS");
6161 cur->set_next_in_collection_set(NULL);
6162 cur->set_in_collection_set(false);
6163 cur->set_young_index_in_cset(-1);
6164 cur = next;
6165 }
6166 }
6167
6168 void G1CollectedHeap::set_free_regions_coming() {
6169 if (G1ConcRegionFreeingVerbose) {
6170 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6171 "setting free regions coming");
6172 }
6173
6174 assert(!free_regions_coming(), "pre-condition");
6175 _free_regions_coming = true;
6176 }
6177
6178 void G1CollectedHeap::reset_free_regions_coming() {
6179 assert(free_regions_coming(), "pre-condition");
6180
6181 {
6182 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6183 _free_regions_coming = false;
6184 SecondaryFreeList_lock->notify_all();
6185 }
6186
6187 if (G1ConcRegionFreeingVerbose) {
6188 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6189 "reset free regions coming");
6190 }
6191 }
6192
6193 void G1CollectedHeap::wait_while_free_regions_coming() {
6194 // Most of the time we won't have to wait, so let's do a quick test
6195 // first before we take the lock.
6196 if (!free_regions_coming()) {
6197 return;
6198 }
6199
6200 if (G1ConcRegionFreeingVerbose) {
6201 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6202 "waiting for free regions");
6203 }
6204
6205 {
6206 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6207 while (free_regions_coming()) {
6208 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6209 }
6210 }
6211
6212 if (G1ConcRegionFreeingVerbose) {
6213 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6214 "done waiting for free regions");
6215 }
6216 }
6217
6218 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6219 assert(heap_lock_held_for_gc(),
6220 "the heap lock should already be held by or for this thread");
6221 _young_list->push_region(hr);
6222 }
6223
6224 class NoYoungRegionsClosure: public HeapRegionClosure {
6225 private:
6226 bool _success;
6227 public:
6228 NoYoungRegionsClosure() : _success(true) { }
6229 bool doHeapRegion(HeapRegion* r) {
6230 if (r->is_young()) {
6231 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6232 r->bottom(), r->end());
6233 _success = false;
6234 }
6235 return false;
6236 }
6237 bool success() { return _success; }
6238 };
6239
6240 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6241 bool ret = _young_list->check_list_empty(check_sample);
6242
6243 if (check_heap) {
6244 NoYoungRegionsClosure closure;
6245 heap_region_iterate(&closure);
6246 ret = ret && closure.success();
6247 }
6248
6249 return ret;
6250 }
6251
6252 class TearDownRegionSetsClosure : public HeapRegionClosure {
6253 private:
6254 OldRegionSet *_old_set;
6255
6256 public:
6257 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6258
6259 bool doHeapRegion(HeapRegion* r) {
6260 if (r->is_empty()) {
6261 // We ignore empty regions, we'll empty the free list afterwards
6262 } else if (r->is_young()) {
6263 // We ignore young regions, we'll empty the young list afterwards
6264 } else if (r->isHumongous()) {
6265 // We ignore humongous regions, we're not tearing down the
6266 // humongous region set
6267 } else {
6268 // The rest should be old
6269 _old_set->remove(r);
6270 }
6271 return false;
6272 }
6273
6274 ~TearDownRegionSetsClosure() {
6275 assert(_old_set->is_empty(), "post-condition");
6276 }
6277 };
6278
6279 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6280 assert_at_safepoint(true /* should_be_vm_thread */);
6281
6282 if (!free_list_only) {
6283 TearDownRegionSetsClosure cl(&_old_set);
6284 heap_region_iterate(&cl);
6285
6286 // Need to do this after the heap iteration to be able to
6287 // recognize the young regions and ignore them during the iteration.
6288 _young_list->empty_list();
6289 }
6290 _free_list.remove_all();
6291 }
6292
6293 class RebuildRegionSetsClosure : public HeapRegionClosure {
6294 private:
6295 bool _free_list_only;
6296 OldRegionSet* _old_set;
6297 FreeRegionList* _free_list;
6298 size_t _total_used;
6299
6300 public:
6301 RebuildRegionSetsClosure(bool free_list_only,
6302 OldRegionSet* old_set, FreeRegionList* free_list) :
6303 _free_list_only(free_list_only),
6304 _old_set(old_set), _free_list(free_list), _total_used(0) {
6305 assert(_free_list->is_empty(), "pre-condition");
6306 if (!free_list_only) {
6307 assert(_old_set->is_empty(), "pre-condition");
6308 }
6309 }
6310
6311 bool doHeapRegion(HeapRegion* r) {
6312 if (r->continuesHumongous()) {
6313 return false;
6314 }
6315
6316 if (r->is_empty()) {
6317 // Add free regions to the free list
6318 _free_list->add_as_tail(r);
6319 } else if (!_free_list_only) {
6320 assert(!r->is_young(), "we should not come across young regions");
6321
6322 if (r->isHumongous()) {
6323 // We ignore humongous regions, we left the humongous set unchanged
6324 } else {
6325 // The rest should be old, add them to the old set
6326 _old_set->add(r);
6327 }
6328 _total_used += r->used();
6329 }
6330
6331 return false;
6332 }
6333
6334 size_t total_used() {
6335 return _total_used;
6336 }
6337 };
6338
6339 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6340 assert_at_safepoint(true /* should_be_vm_thread */);
6341
6342 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6343 heap_region_iterate(&cl);
6344
6345 if (!free_list_only) {
6346 _summary_bytes_used = cl.total_used();
6347 }
6348 assert(_summary_bytes_used == recalculate_used(),
6349 err_msg("inconsistent _summary_bytes_used, "
6350 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6351 _summary_bytes_used, recalculate_used()));
6352 }
6353
6354 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6355 _refine_cte_cl->set_concurrent(concurrent);
6356 }
6357
6358 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6359 HeapRegion* hr = heap_region_containing(p);
6360 if (hr == NULL) {
6361 return false;
6362 } else {
6363 return hr->is_in(p);
6364 }
6365 }
6366
6367 // Methods for the mutator alloc region
6368
6369 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6370 bool force) {
6371 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6372 assert(!force || g1_policy()->can_expand_young_list(),
6373 "if force is true we should be able to expand the young list");
6374 bool young_list_full = g1_policy()->is_young_list_full();
6375 if (force || !young_list_full) {
6376 HeapRegion* new_alloc_region = new_region(word_size,
6377 false /* do_expand */);
6378 if (new_alloc_region != NULL) {
6379 set_region_short_lived_locked(new_alloc_region);
6380 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6381 return new_alloc_region;
6382 }
6383 }
6384 return NULL;
6385 }
6386
6387 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6388 size_t allocated_bytes) {
6389 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6390 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6391
6392 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6393 _summary_bytes_used += allocated_bytes;
6394 _hr_printer.retire(alloc_region);
6395 // We update the eden sizes here, when the region is retired,
6396 // instead of when it's allocated, since this is the point that its
6397 // used space has been recored in _summary_bytes_used.
6398 g1mm()->update_eden_size();
6399 }
6400
6401 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6402 bool force) {
6403 return _g1h->new_mutator_alloc_region(word_size, force);
6404 }
6405
6406 void G1CollectedHeap::set_par_threads() {
6407 // Don't change the number of workers. Use the value previously set
6408 // in the workgroup.
6409 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6410 uint n_workers = workers()->active_workers();
6411 assert(UseDynamicNumberOfGCThreads ||
6412 n_workers == workers()->total_workers(),
6413 "Otherwise should be using the total number of workers");
6414 if (n_workers == 0) {
6415 assert(false, "Should have been set in prior evacuation pause.");
6416 n_workers = ParallelGCThreads;
6417 workers()->set_active_workers(n_workers);
6418 }
6419 set_par_threads(n_workers);
6420 }
6421
6422 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6423 size_t allocated_bytes) {
6424 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6425 }
6426
6427 // Methods for the GC alloc regions
6428
6429 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6430 uint count,
6431 GCAllocPurpose ap) {
6432 assert(FreeList_lock->owned_by_self(), "pre-condition");
6433
6434 if (count < g1_policy()->max_regions(ap)) {
6435 HeapRegion* new_alloc_region = new_region(word_size,
6436 true /* do_expand */);
6437 if (new_alloc_region != NULL) {
6438 // We really only need to do this for old regions given that we
6439 // should never scan survivors. But it doesn't hurt to do it
6440 // for survivors too.
6441 new_alloc_region->set_saved_mark();
6442 if (ap == GCAllocForSurvived) {
6443 new_alloc_region->set_survivor();
6444 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6445 } else {
6446 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6447 }
6448 bool during_im = g1_policy()->during_initial_mark_pause();
6449 new_alloc_region->note_start_of_copying(during_im);
6450 return new_alloc_region;
6451 } else {
6452 g1_policy()->note_alloc_region_limit_reached(ap);
6453 }
6454 }
6455 return NULL;
6456 }
6457
6458 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6459 size_t allocated_bytes,
6460 GCAllocPurpose ap) {
6461 bool during_im = g1_policy()->during_initial_mark_pause();
6462 alloc_region->note_end_of_copying(during_im);
6463 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6464 if (ap == GCAllocForSurvived) {
6465 young_list()->add_survivor_region(alloc_region);
6466 } else {
6467 _old_set.add(alloc_region);
6468 }
6469 _hr_printer.retire(alloc_region);
6470 }
6471
6472 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6473 bool force) {
6474 assert(!force, "not supported for GC alloc regions");
6475 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6476 }
6477
6478 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6479 size_t allocated_bytes) {
6480 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6481 GCAllocForSurvived);
6482 }
6483
6484 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6485 bool force) {
6486 assert(!force, "not supported for GC alloc regions");
6487 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6488 }
6489
6490 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6491 size_t allocated_bytes) {
6492 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6493 GCAllocForTenured);
6494 }
6495 // Heap region set verification
6496
6497 class VerifyRegionListsClosure : public HeapRegionClosure {
6498 private:
6499 FreeRegionList* _free_list;
6500 OldRegionSet* _old_set;
6501 HumongousRegionSet* _humongous_set;
6502 uint _region_count;
6503
6504 public:
6505 VerifyRegionListsClosure(OldRegionSet* old_set,
6506 HumongousRegionSet* humongous_set,
6507 FreeRegionList* free_list) :
6508 _old_set(old_set), _humongous_set(humongous_set),
6509 _free_list(free_list), _region_count(0) { }
6510
6511 uint region_count() { return _region_count; }
6512
6513 bool doHeapRegion(HeapRegion* hr) {
6514 _region_count += 1;
6515
6516 if (hr->continuesHumongous()) {
6517 return false;
6518 }
6519
6520 if (hr->is_young()) {
6521 // TODO
6522 } else if (hr->startsHumongous()) {
6523 _humongous_set->verify_next_region(hr);
6524 } else if (hr->is_empty()) {
6525 _free_list->verify_next_region(hr);
6526 } else {
6527 _old_set->verify_next_region(hr);
6528 }
6529 return false;
6530 }
6531 };
6532
6533 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6534 HeapWord* bottom) {
6535 HeapWord* end = bottom + HeapRegion::GrainWords;
6536 MemRegion mr(bottom, end);
6537 assert(_g1_reserved.contains(mr), "invariant");
6538 // This might return NULL if the allocation fails
6539 return new HeapRegion(hrs_index, _bot_shared, mr);
6540 }
6541
6542 void G1CollectedHeap::verify_region_sets() {
6543 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6544
6545 // First, check the explicit lists.
6546 _free_list.verify();
6547 {
6548 // Given that a concurrent operation might be adding regions to
6549 // the secondary free list we have to take the lock before
6550 // verifying it.
6551 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6552 _secondary_free_list.verify();
6553 }
6554 _old_set.verify();
6555 _humongous_set.verify();
6556
6557 // If a concurrent region freeing operation is in progress it will
6558 // be difficult to correctly attributed any free regions we come
6559 // across to the correct free list given that they might belong to
6560 // one of several (free_list, secondary_free_list, any local lists,
6561 // etc.). So, if that's the case we will skip the rest of the
6562 // verification operation. Alternatively, waiting for the concurrent
6563 // operation to complete will have a non-trivial effect on the GC's
6564 // operation (no concurrent operation will last longer than the
6565 // interval between two calls to verification) and it might hide
6566 // any issues that we would like to catch during testing.
6567 if (free_regions_coming()) {
6568 return;
6569 }
6570
6571 // Make sure we append the secondary_free_list on the free_list so
6572 // that all free regions we will come across can be safely
6573 // attributed to the free_list.
6574 append_secondary_free_list_if_not_empty_with_lock();
6575
6576 // Finally, make sure that the region accounting in the lists is
6577 // consistent with what we see in the heap.
6578 _old_set.verify_start();
6579 _humongous_set.verify_start();
6580 _free_list.verify_start();
6581
6582 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6583 heap_region_iterate(&cl);
6584
6585 _old_set.verify_end();
6586 _humongous_set.verify_end();
6587 _free_list.verify_end();
6588 }