1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
35 #include "gc_implementation/g1/g1EvacFailure.hpp"
36 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
37 #include "gc_implementation/g1/g1Log.hpp"
38 #include "gc_implementation/g1/g1MarkSweep.hpp"
39 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
40 #include "gc_implementation/g1/g1RemSet.inline.hpp"
41 #include "gc_implementation/g1/g1YCTypes.hpp"
42 #include "gc_implementation/g1/heapRegion.inline.hpp"
43 #include "gc_implementation/g1/heapRegionRemSet.hpp"
44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
45 #include "gc_implementation/g1/vm_operations_g1.hpp"
46 #include "gc_implementation/shared/gcHeapSummary.hpp"
47 #include "gc_implementation/shared/gcTimer.hpp"
48 #include "gc_implementation/shared/gcTrace.hpp"
49 #include "gc_implementation/shared/gcTraceTime.hpp"
50 #include "gc_implementation/shared/isGCActiveMark.hpp"
51 #include "memory/gcLocker.inline.hpp"
52 #include "memory/genOopClosures.inline.hpp"
53 #include "memory/generationSpec.hpp"
54 #include "memory/referenceProcessor.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "oops/oop.pcgc.inline.hpp"
57 #include "runtime/aprofiler.hpp"
58 #include "runtime/vmThread.hpp"
59
60 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
61
62 // turn it on so that the contents of the young list (scan-only /
63 // to-be-collected) are printed at "strategic" points before / during
64 // / after the collection --- this is useful for debugging
65 #define YOUNG_LIST_VERBOSE 0
66 // CURRENT STATUS
67 // This file is under construction. Search for "FIXME".
68
69 // INVARIANTS/NOTES
70 //
71 // All allocation activity covered by the G1CollectedHeap interface is
72 // serialized by acquiring the HeapLock. This happens in mem_allocate
73 // and allocate_new_tlab, which are the "entry" points to the
74 // allocation code from the rest of the JVM. (Note that this does not
75 // apply to TLAB allocation, which is not part of this interface: it
76 // is done by clients of this interface.)
77
78 // Notes on implementation of parallelism in different tasks.
79 //
80 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
81 // The number of GC workers is passed to heap_region_par_iterate_chunked().
82 // It does use run_task() which sets _n_workers in the task.
83 // G1ParTask executes g1_process_strong_roots() ->
84 // SharedHeap::process_strong_roots() which calls eventually to
85 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
86 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
87 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
88 //
89
90 // Local to this file.
91
92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
93 SuspendibleThreadSet* _sts;
94 G1RemSet* _g1rs;
95 ConcurrentG1Refine* _cg1r;
96 bool _concurrent;
97 public:
98 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
99 G1RemSet* g1rs,
100 ConcurrentG1Refine* cg1r) :
101 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
102 {}
103 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
104 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
105 // This path is executed by the concurrent refine or mutator threads,
106 // concurrently, and so we do not care if card_ptr contains references
107 // that point into the collection set.
108 assert(!oops_into_cset, "should be");
109
110 if (_concurrent && _sts->should_yield()) {
111 // Caller will actually yield.
112 return false;
113 }
114 // Otherwise, we finished successfully; return true.
115 return true;
116 }
117 void set_concurrent(bool b) { _concurrent = b; }
118 };
119
120
121 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
122 int _calls;
123 G1CollectedHeap* _g1h;
124 CardTableModRefBS* _ctbs;
125 int _histo[256];
126 public:
127 ClearLoggedCardTableEntryClosure() :
128 _calls(0)
129 {
130 _g1h = G1CollectedHeap::heap();
131 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
132 for (int i = 0; i < 256; i++) _histo[i] = 0;
133 }
134 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
135 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
136 _calls++;
137 unsigned char* ujb = (unsigned char*)card_ptr;
138 int ind = (int)(*ujb);
139 _histo[ind]++;
140 *card_ptr = -1;
141 }
142 return true;
143 }
144 int calls() { return _calls; }
145 void print_histo() {
146 gclog_or_tty->print_cr("Card table value histogram:");
147 for (int i = 0; i < 256; i++) {
148 if (_histo[i] != 0) {
149 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
150 }
151 }
152 }
153 };
154
155 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
156 int _calls;
157 G1CollectedHeap* _g1h;
158 CardTableModRefBS* _ctbs;
159 public:
160 RedirtyLoggedCardTableEntryClosure() :
161 _calls(0)
162 {
163 _g1h = G1CollectedHeap::heap();
164 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
165 }
166 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
167 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
168 _calls++;
169 *card_ptr = 0;
170 }
171 return true;
172 }
173 int calls() { return _calls; }
174 };
175
176 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
177 public:
178 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
179 *card_ptr = CardTableModRefBS::dirty_card_val();
180 return true;
181 }
182 };
183
184 YoungList::YoungList(G1CollectedHeap* g1h) :
185 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
186 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
187 guarantee(check_list_empty(false), "just making sure...");
188 }
189
190 void YoungList::push_region(HeapRegion *hr) {
191 assert(!hr->is_young(), "should not already be young");
192 assert(hr->get_next_young_region() == NULL, "cause it should!");
193
194 hr->set_next_young_region(_head);
195 _head = hr;
196
197 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
198 ++_length;
199 }
200
201 void YoungList::add_survivor_region(HeapRegion* hr) {
202 assert(hr->is_survivor(), "should be flagged as survivor region");
203 assert(hr->get_next_young_region() == NULL, "cause it should!");
204
205 hr->set_next_young_region(_survivor_head);
206 if (_survivor_head == NULL) {
207 _survivor_tail = hr;
208 }
209 _survivor_head = hr;
210 ++_survivor_length;
211 }
212
213 void YoungList::empty_list(HeapRegion* list) {
214 while (list != NULL) {
215 HeapRegion* next = list->get_next_young_region();
216 list->set_next_young_region(NULL);
217 list->uninstall_surv_rate_group();
218 list->set_not_young();
219 list = next;
220 }
221 }
222
223 void YoungList::empty_list() {
224 assert(check_list_well_formed(), "young list should be well formed");
225
226 empty_list(_head);
227 _head = NULL;
228 _length = 0;
229
230 empty_list(_survivor_head);
231 _survivor_head = NULL;
232 _survivor_tail = NULL;
233 _survivor_length = 0;
234
235 _last_sampled_rs_lengths = 0;
236
237 assert(check_list_empty(false), "just making sure...");
238 }
239
240 bool YoungList::check_list_well_formed() {
241 bool ret = true;
242
243 uint length = 0;
244 HeapRegion* curr = _head;
245 HeapRegion* last = NULL;
246 while (curr != NULL) {
247 if (!curr->is_young()) {
248 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
249 "incorrectly tagged (y: %d, surv: %d)",
250 curr->bottom(), curr->end(),
251 curr->is_young(), curr->is_survivor());
252 ret = false;
253 }
254 ++length;
255 last = curr;
256 curr = curr->get_next_young_region();
257 }
258 ret = ret && (length == _length);
259
260 if (!ret) {
261 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
262 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
263 length, _length);
264 }
265
266 return ret;
267 }
268
269 bool YoungList::check_list_empty(bool check_sample) {
270 bool ret = true;
271
272 if (_length != 0) {
273 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
274 _length);
275 ret = false;
276 }
277 if (check_sample && _last_sampled_rs_lengths != 0) {
278 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
279 ret = false;
280 }
281 if (_head != NULL) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
283 ret = false;
284 }
285 if (!ret) {
286 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
287 }
288
289 return ret;
290 }
291
292 void
293 YoungList::rs_length_sampling_init() {
294 _sampled_rs_lengths = 0;
295 _curr = _head;
296 }
297
298 bool
299 YoungList::rs_length_sampling_more() {
300 return _curr != NULL;
301 }
302
303 void
304 YoungList::rs_length_sampling_next() {
305 assert( _curr != NULL, "invariant" );
306 size_t rs_length = _curr->rem_set()->occupied();
307
308 _sampled_rs_lengths += rs_length;
309
310 // The current region may not yet have been added to the
311 // incremental collection set (it gets added when it is
312 // retired as the current allocation region).
313 if (_curr->in_collection_set()) {
314 // Update the collection set policy information for this region
315 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
316 }
317
318 _curr = _curr->get_next_young_region();
319 if (_curr == NULL) {
320 _last_sampled_rs_lengths = _sampled_rs_lengths;
321 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
322 }
323 }
324
325 void
326 YoungList::reset_auxilary_lists() {
327 guarantee( is_empty(), "young list should be empty" );
328 assert(check_list_well_formed(), "young list should be well formed");
329
330 // Add survivor regions to SurvRateGroup.
331 _g1h->g1_policy()->note_start_adding_survivor_regions();
332 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
333
334 int young_index_in_cset = 0;
335 for (HeapRegion* curr = _survivor_head;
336 curr != NULL;
337 curr = curr->get_next_young_region()) {
338 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
339
340 // The region is a non-empty survivor so let's add it to
341 // the incremental collection set for the next evacuation
342 // pause.
343 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
344 young_index_in_cset += 1;
345 }
346 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
347 _g1h->g1_policy()->note_stop_adding_survivor_regions();
348
349 _head = _survivor_head;
350 _length = _survivor_length;
351 if (_survivor_head != NULL) {
352 assert(_survivor_tail != NULL, "cause it shouldn't be");
353 assert(_survivor_length > 0, "invariant");
354 _survivor_tail->set_next_young_region(NULL);
355 }
356
357 // Don't clear the survivor list handles until the start of
358 // the next evacuation pause - we need it in order to re-tag
359 // the survivor regions from this evacuation pause as 'young'
360 // at the start of the next.
361
362 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
363
364 assert(check_list_well_formed(), "young list should be well formed");
365 }
366
367 void YoungList::print() {
368 HeapRegion* lists[] = {_head, _survivor_head};
369 const char* names[] = {"YOUNG", "SURVIVOR"};
370
371 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
372 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
373 HeapRegion *curr = lists[list];
374 if (curr == NULL)
375 gclog_or_tty->print_cr(" empty");
376 while (curr != NULL) {
377 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
378 HR_FORMAT_PARAMS(curr),
379 curr->prev_top_at_mark_start(),
380 curr->next_top_at_mark_start(),
381 curr->age_in_surv_rate_group_cond());
382 curr = curr->get_next_young_region();
383 }
384 }
385
386 gclog_or_tty->print_cr("");
387 }
388
389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
390 {
391 // Claim the right to put the region on the dirty cards region list
392 // by installing a self pointer.
393 HeapRegion* next = hr->get_next_dirty_cards_region();
394 if (next == NULL) {
395 HeapRegion* res = (HeapRegion*)
396 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
397 NULL);
398 if (res == NULL) {
399 HeapRegion* head;
400 do {
401 // Put the region to the dirty cards region list.
402 head = _dirty_cards_region_list;
403 next = (HeapRegion*)
404 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
405 if (next == head) {
406 assert(hr->get_next_dirty_cards_region() == hr,
407 "hr->get_next_dirty_cards_region() != hr");
408 if (next == NULL) {
409 // The last region in the list points to itself.
410 hr->set_next_dirty_cards_region(hr);
411 } else {
412 hr->set_next_dirty_cards_region(next);
413 }
414 }
415 } while (next != head);
416 }
417 }
418 }
419
420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
421 {
422 HeapRegion* head;
423 HeapRegion* hr;
424 do {
425 head = _dirty_cards_region_list;
426 if (head == NULL) {
427 return NULL;
428 }
429 HeapRegion* new_head = head->get_next_dirty_cards_region();
430 if (head == new_head) {
431 // The last region.
432 new_head = NULL;
433 }
434 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
435 head);
436 } while (hr != head);
437 assert(hr != NULL, "invariant");
438 hr->set_next_dirty_cards_region(NULL);
439 return hr;
440 }
441
442 void G1CollectedHeap::stop_conc_gc_threads() {
443 _cg1r->stop();
444 _cmThread->stop();
445 }
446
447 #ifdef ASSERT
448 // A region is added to the collection set as it is retired
449 // so an address p can point to a region which will be in the
450 // collection set but has not yet been retired. This method
451 // therefore is only accurate during a GC pause after all
452 // regions have been retired. It is used for debugging
453 // to check if an nmethod has references to objects that can
454 // be move during a partial collection. Though it can be
455 // inaccurate, it is sufficient for G1 because the conservative
456 // implementation of is_scavengable() for G1 will indicate that
457 // all nmethods must be scanned during a partial collection.
458 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
459 HeapRegion* hr = heap_region_containing(p);
460 return hr != NULL && hr->in_collection_set();
461 }
462 #endif
463
464 // Returns true if the reference points to an object that
465 // can move in an incremental collection.
466 bool G1CollectedHeap::is_scavengable(const void* p) {
467 G1CollectedHeap* g1h = G1CollectedHeap::heap();
468 G1CollectorPolicy* g1p = g1h->g1_policy();
469 HeapRegion* hr = heap_region_containing(p);
470 if (hr == NULL) {
471 // null
472 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
473 return false;
474 } else {
475 return !hr->isHumongous();
476 }
477 }
478
479 void G1CollectedHeap::check_ct_logs_at_safepoint() {
480 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
481 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
482
483 // Count the dirty cards at the start.
484 CountNonCleanMemRegionClosure count1(this);
485 ct_bs->mod_card_iterate(&count1);
486 int orig_count = count1.n();
487
488 // First clear the logged cards.
489 ClearLoggedCardTableEntryClosure clear;
490 dcqs.set_closure(&clear);
491 dcqs.apply_closure_to_all_completed_buffers();
492 dcqs.iterate_closure_all_threads(false);
493 clear.print_histo();
494
495 // Now ensure that there's no dirty cards.
496 CountNonCleanMemRegionClosure count2(this);
497 ct_bs->mod_card_iterate(&count2);
498 if (count2.n() != 0) {
499 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
500 count2.n(), orig_count);
501 }
502 guarantee(count2.n() == 0, "Card table should be clean.");
503
504 RedirtyLoggedCardTableEntryClosure redirty;
505 JavaThread::dirty_card_queue_set().set_closure(&redirty);
506 dcqs.apply_closure_to_all_completed_buffers();
507 dcqs.iterate_closure_all_threads(false);
508 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
509 clear.calls(), orig_count);
510 guarantee(redirty.calls() == clear.calls(),
511 "Or else mechanism is broken.");
512
513 CountNonCleanMemRegionClosure count3(this);
514 ct_bs->mod_card_iterate(&count3);
515 if (count3.n() != orig_count) {
516 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
517 orig_count, count3.n());
518 guarantee(count3.n() >= orig_count, "Should have restored them all.");
519 }
520
521 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
522 }
523
524 // Private class members.
525
526 G1CollectedHeap* G1CollectedHeap::_g1h;
527
528 // Private methods.
529
530 HeapRegion*
531 G1CollectedHeap::new_region_try_secondary_free_list() {
532 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
533 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
534 if (!_secondary_free_list.is_empty()) {
535 if (G1ConcRegionFreeingVerbose) {
536 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
537 "secondary_free_list has %u entries",
538 _secondary_free_list.length());
539 }
540 // It looks as if there are free regions available on the
541 // secondary_free_list. Let's move them to the free_list and try
542 // again to allocate from it.
543 append_secondary_free_list();
544
545 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
546 "empty we should have moved at least one entry to the free_list");
547 HeapRegion* res = _free_list.remove_head();
548 if (G1ConcRegionFreeingVerbose) {
549 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
550 "allocated "HR_FORMAT" from secondary_free_list",
551 HR_FORMAT_PARAMS(res));
552 }
553 return res;
554 }
555
556 // Wait here until we get notified either when (a) there are no
557 // more free regions coming or (b) some regions have been moved on
558 // the secondary_free_list.
559 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
560 }
561
562 if (G1ConcRegionFreeingVerbose) {
563 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
564 "could not allocate from secondary_free_list");
565 }
566 return NULL;
567 }
568
569 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
570 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
571 "the only time we use this to allocate a humongous region is "
572 "when we are allocating a single humongous region");
573
574 HeapRegion* res;
575 if (G1StressConcRegionFreeing) {
576 if (!_secondary_free_list.is_empty()) {
577 if (G1ConcRegionFreeingVerbose) {
578 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
579 "forced to look at the secondary_free_list");
580 }
581 res = new_region_try_secondary_free_list();
582 if (res != NULL) {
583 return res;
584 }
585 }
586 }
587 res = _free_list.remove_head_or_null();
588 if (res == NULL) {
589 if (G1ConcRegionFreeingVerbose) {
590 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
591 "res == NULL, trying the secondary_free_list");
592 }
593 res = new_region_try_secondary_free_list();
594 }
595 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
596 // Currently, only attempts to allocate GC alloc regions set
597 // do_expand to true. So, we should only reach here during a
598 // safepoint. If this assumption changes we might have to
599 // reconsider the use of _expand_heap_after_alloc_failure.
600 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
601
602 ergo_verbose1(ErgoHeapSizing,
603 "attempt heap expansion",
604 ergo_format_reason("region allocation request failed")
605 ergo_format_byte("allocation request"),
606 word_size * HeapWordSize);
607 if (expand(word_size * HeapWordSize)) {
608 // Given that expand() succeeded in expanding the heap, and we
609 // always expand the heap by an amount aligned to the heap
610 // region size, the free list should in theory not be empty. So
611 // it would probably be OK to use remove_head(). But the extra
612 // check for NULL is unlikely to be a performance issue here (we
613 // just expanded the heap!) so let's just be conservative and
614 // use remove_head_or_null().
615 res = _free_list.remove_head_or_null();
616 } else {
617 _expand_heap_after_alloc_failure = false;
618 }
619 }
620 return res;
621 }
622
623 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
624 size_t word_size) {
625 assert(isHumongous(word_size), "word_size should be humongous");
626 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
627
628 uint first = G1_NULL_HRS_INDEX;
629 if (num_regions == 1) {
630 // Only one region to allocate, no need to go through the slower
631 // path. The caller will attempt the expansion if this fails, so
632 // let's not try to expand here too.
633 HeapRegion* hr = new_region(word_size, false /* do_expand */);
634 if (hr != NULL) {
635 first = hr->hrs_index();
636 } else {
637 first = G1_NULL_HRS_INDEX;
638 }
639 } else {
640 // We can't allocate humongous regions while cleanupComplete() is
641 // running, since some of the regions we find to be empty might not
642 // yet be added to the free list and it is not straightforward to
643 // know which list they are on so that we can remove them. Note
644 // that we only need to do this if we need to allocate more than
645 // one region to satisfy the current humongous allocation
646 // request. If we are only allocating one region we use the common
647 // region allocation code (see above).
648 wait_while_free_regions_coming();
649 append_secondary_free_list_if_not_empty_with_lock();
650
651 if (free_regions() >= num_regions) {
652 first = _hrs.find_contiguous(num_regions);
653 if (first != G1_NULL_HRS_INDEX) {
654 for (uint i = first; i < first + num_regions; ++i) {
655 HeapRegion* hr = region_at(i);
656 assert(hr->is_empty(), "sanity");
657 assert(is_on_master_free_list(hr), "sanity");
658 hr->set_pending_removal(true);
659 }
660 _free_list.remove_all_pending(num_regions);
661 }
662 }
663 }
664 return first;
665 }
666
667 HeapWord*
668 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
669 uint num_regions,
670 size_t word_size) {
671 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
672 assert(isHumongous(word_size), "word_size should be humongous");
673 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
674
675 // Index of last region in the series + 1.
676 uint last = first + num_regions;
677
678 // We need to initialize the region(s) we just discovered. This is
679 // a bit tricky given that it can happen concurrently with
680 // refinement threads refining cards on these regions and
681 // potentially wanting to refine the BOT as they are scanning
682 // those cards (this can happen shortly after a cleanup; see CR
683 // 6991377). So we have to set up the region(s) carefully and in
684 // a specific order.
685
686 // The word size sum of all the regions we will allocate.
687 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
688 assert(word_size <= word_size_sum, "sanity");
689
690 // This will be the "starts humongous" region.
691 HeapRegion* first_hr = region_at(first);
692 // The header of the new object will be placed at the bottom of
693 // the first region.
694 HeapWord* new_obj = first_hr->bottom();
695 // This will be the new end of the first region in the series that
696 // should also match the end of the last region in the series.
697 HeapWord* new_end = new_obj + word_size_sum;
698 // This will be the new top of the first region that will reflect
699 // this allocation.
700 HeapWord* new_top = new_obj + word_size;
701
702 // First, we need to zero the header of the space that we will be
703 // allocating. When we update top further down, some refinement
704 // threads might try to scan the region. By zeroing the header we
705 // ensure that any thread that will try to scan the region will
706 // come across the zero klass word and bail out.
707 //
708 // NOTE: It would not have been correct to have used
709 // CollectedHeap::fill_with_object() and make the space look like
710 // an int array. The thread that is doing the allocation will
711 // later update the object header to a potentially different array
712 // type and, for a very short period of time, the klass and length
713 // fields will be inconsistent. This could cause a refinement
714 // thread to calculate the object size incorrectly.
715 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
716
717 // We will set up the first region as "starts humongous". This
718 // will also update the BOT covering all the regions to reflect
719 // that there is a single object that starts at the bottom of the
720 // first region.
721 first_hr->set_startsHumongous(new_top, new_end);
722
723 // Then, if there are any, we will set up the "continues
724 // humongous" regions.
725 HeapRegion* hr = NULL;
726 for (uint i = first + 1; i < last; ++i) {
727 hr = region_at(i);
728 hr->set_continuesHumongous(first_hr);
729 }
730 // If we have "continues humongous" regions (hr != NULL), then the
731 // end of the last one should match new_end.
732 assert(hr == NULL || hr->end() == new_end, "sanity");
733
734 // Up to this point no concurrent thread would have been able to
735 // do any scanning on any region in this series. All the top
736 // fields still point to bottom, so the intersection between
737 // [bottom,top] and [card_start,card_end] will be empty. Before we
738 // update the top fields, we'll do a storestore to make sure that
739 // no thread sees the update to top before the zeroing of the
740 // object header and the BOT initialization.
741 OrderAccess::storestore();
742
743 // Now that the BOT and the object header have been initialized,
744 // we can update top of the "starts humongous" region.
745 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
746 "new_top should be in this region");
747 first_hr->set_top(new_top);
748 if (_hr_printer.is_active()) {
749 HeapWord* bottom = first_hr->bottom();
750 HeapWord* end = first_hr->orig_end();
751 if ((first + 1) == last) {
752 // the series has a single humongous region
753 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
754 } else {
755 // the series has more than one humongous regions
756 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
757 }
758 }
759
760 // Now, we will update the top fields of the "continues humongous"
761 // regions. The reason we need to do this is that, otherwise,
762 // these regions would look empty and this will confuse parts of
763 // G1. For example, the code that looks for a consecutive number
764 // of empty regions will consider them empty and try to
765 // re-allocate them. We can extend is_empty() to also include
766 // !continuesHumongous(), but it is easier to just update the top
767 // fields here. The way we set top for all regions (i.e., top ==
768 // end for all regions but the last one, top == new_top for the
769 // last one) is actually used when we will free up the humongous
770 // region in free_humongous_region().
771 hr = NULL;
772 for (uint i = first + 1; i < last; ++i) {
773 hr = region_at(i);
774 if ((i + 1) == last) {
775 // last continues humongous region
776 assert(hr->bottom() < new_top && new_top <= hr->end(),
777 "new_top should fall on this region");
778 hr->set_top(new_top);
779 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
780 } else {
781 // not last one
782 assert(new_top > hr->end(), "new_top should be above this region");
783 hr->set_top(hr->end());
784 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
785 }
786 }
787 // If we have continues humongous regions (hr != NULL), then the
788 // end of the last one should match new_end and its top should
789 // match new_top.
790 assert(hr == NULL ||
791 (hr->end() == new_end && hr->top() == new_top), "sanity");
792
793 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
794 _summary_bytes_used += first_hr->used();
795 _humongous_set.add(first_hr);
796
797 return new_obj;
798 }
799
800 // If could fit into free regions w/o expansion, try.
801 // Otherwise, if can expand, do so.
802 // Otherwise, if using ex regions might help, try with ex given back.
803 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
804 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
805
806 verify_region_sets_optional();
807
808 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
809 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
810 uint x_num = expansion_regions();
811 uint fs = _hrs.free_suffix();
812 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
813 if (first == G1_NULL_HRS_INDEX) {
814 // The only thing we can do now is attempt expansion.
815 if (fs + x_num >= num_regions) {
816 // If the number of regions we're trying to allocate for this
817 // object is at most the number of regions in the free suffix,
818 // then the call to humongous_obj_allocate_find_first() above
819 // should have succeeded and we wouldn't be here.
820 //
821 // We should only be trying to expand when the free suffix is
822 // not sufficient for the object _and_ we have some expansion
823 // room available.
824 assert(num_regions > fs, "earlier allocation should have succeeded");
825
826 ergo_verbose1(ErgoHeapSizing,
827 "attempt heap expansion",
828 ergo_format_reason("humongous allocation request failed")
829 ergo_format_byte("allocation request"),
830 word_size * HeapWordSize);
831 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
832 // Even though the heap was expanded, it might not have
833 // reached the desired size. So, we cannot assume that the
834 // allocation will succeed.
835 first = humongous_obj_allocate_find_first(num_regions, word_size);
836 }
837 }
838 }
839
840 HeapWord* result = NULL;
841 if (first != G1_NULL_HRS_INDEX) {
842 result =
843 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
844 assert(result != NULL, "it should always return a valid result");
845
846 // A successful humongous object allocation changes the used space
847 // information of the old generation so we need to recalculate the
848 // sizes and update the jstat counters here.
849 g1mm()->update_sizes();
850 }
851
852 verify_region_sets_optional();
853
854 return result;
855 }
856
857 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
858 assert_heap_not_locked_and_not_at_safepoint();
859 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
860
861 unsigned int dummy_gc_count_before;
862 int dummy_gclocker_retry_count = 0;
863 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
864 }
865
866 HeapWord*
867 G1CollectedHeap::mem_allocate(size_t word_size,
868 bool* gc_overhead_limit_was_exceeded) {
869 assert_heap_not_locked_and_not_at_safepoint();
870
871 // Loop until the allocation is satisfied, or unsatisfied after GC.
872 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
873 unsigned int gc_count_before;
874
875 HeapWord* result = NULL;
876 if (!isHumongous(word_size)) {
877 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
878 } else {
879 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
880 }
881 if (result != NULL) {
882 return result;
883 }
884
885 // Create the garbage collection operation...
886 VM_G1CollectForAllocation op(gc_count_before, word_size);
887 // ...and get the VM thread to execute it.
888 VMThread::execute(&op);
889
890 if (op.prologue_succeeded() && op.pause_succeeded()) {
891 // If the operation was successful we'll return the result even
892 // if it is NULL. If the allocation attempt failed immediately
893 // after a Full GC, it's unlikely we'll be able to allocate now.
894 HeapWord* result = op.result();
895 if (result != NULL && !isHumongous(word_size)) {
896 // Allocations that take place on VM operations do not do any
897 // card dirtying and we have to do it here. We only have to do
898 // this for non-humongous allocations, though.
899 dirty_young_block(result, word_size);
900 }
901 return result;
902 } else {
903 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
904 return NULL;
905 }
906 assert(op.result() == NULL,
907 "the result should be NULL if the VM op did not succeed");
908 }
909
910 // Give a warning if we seem to be looping forever.
911 if ((QueuedAllocationWarningCount > 0) &&
912 (try_count % QueuedAllocationWarningCount == 0)) {
913 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
914 }
915 }
916
917 ShouldNotReachHere();
918 return NULL;
919 }
920
921 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
922 unsigned int *gc_count_before_ret,
923 int* gclocker_retry_count_ret) {
924 // Make sure you read the note in attempt_allocation_humongous().
925
926 assert_heap_not_locked_and_not_at_safepoint();
927 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
928 "be called for humongous allocation requests");
929
930 // We should only get here after the first-level allocation attempt
931 // (attempt_allocation()) failed to allocate.
932
933 // We will loop until a) we manage to successfully perform the
934 // allocation or b) we successfully schedule a collection which
935 // fails to perform the allocation. b) is the only case when we'll
936 // return NULL.
937 HeapWord* result = NULL;
938 for (int try_count = 1; /* we'll return */; try_count += 1) {
939 bool should_try_gc;
940 unsigned int gc_count_before;
941
942 {
943 MutexLockerEx x(Heap_lock);
944
945 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
946 false /* bot_updates */);
947 if (result != NULL) {
948 return result;
949 }
950
951 // If we reach here, attempt_allocation_locked() above failed to
952 // allocate a new region. So the mutator alloc region should be NULL.
953 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
954
955 if (GC_locker::is_active_and_needs_gc()) {
956 if (g1_policy()->can_expand_young_list()) {
957 // No need for an ergo verbose message here,
958 // can_expand_young_list() does this when it returns true.
959 result = _mutator_alloc_region.attempt_allocation_force(word_size,
960 false /* bot_updates */);
961 if (result != NULL) {
962 return result;
963 }
964 }
965 should_try_gc = false;
966 } else {
967 // The GCLocker may not be active but the GCLocker initiated
968 // GC may not yet have been performed (GCLocker::needs_gc()
969 // returns true). In this case we do not try this GC and
970 // wait until the GCLocker initiated GC is performed, and
971 // then retry the allocation.
972 if (GC_locker::needs_gc()) {
973 should_try_gc = false;
974 } else {
975 // Read the GC count while still holding the Heap_lock.
976 gc_count_before = total_collections();
977 should_try_gc = true;
978 }
979 }
980 }
981
982 if (should_try_gc) {
983 bool succeeded;
984 result = do_collection_pause(word_size, gc_count_before, &succeeded);
985 if (result != NULL) {
986 assert(succeeded, "only way to get back a non-NULL result");
987 return result;
988 }
989
990 if (succeeded) {
991 // If we get here we successfully scheduled a collection which
992 // failed to allocate. No point in trying to allocate
993 // further. We'll just return NULL.
994 MutexLockerEx x(Heap_lock);
995 *gc_count_before_ret = total_collections();
996 return NULL;
997 }
998 } else {
999 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1000 MutexLockerEx x(Heap_lock);
1001 *gc_count_before_ret = total_collections();
1002 return NULL;
1003 }
1004 // The GCLocker is either active or the GCLocker initiated
1005 // GC has not yet been performed. Stall until it is and
1006 // then retry the allocation.
1007 GC_locker::stall_until_clear();
1008 (*gclocker_retry_count_ret) += 1;
1009 }
1010
1011 // We can reach here if we were unsuccessful in scheduling a
1012 // collection (because another thread beat us to it) or if we were
1013 // stalled due to the GC locker. In either can we should retry the
1014 // allocation attempt in case another thread successfully
1015 // performed a collection and reclaimed enough space. We do the
1016 // first attempt (without holding the Heap_lock) here and the
1017 // follow-on attempt will be at the start of the next loop
1018 // iteration (after taking the Heap_lock).
1019 result = _mutator_alloc_region.attempt_allocation(word_size,
1020 false /* bot_updates */);
1021 if (result != NULL) {
1022 return result;
1023 }
1024
1025 // Give a warning if we seem to be looping forever.
1026 if ((QueuedAllocationWarningCount > 0) &&
1027 (try_count % QueuedAllocationWarningCount == 0)) {
1028 warning("G1CollectedHeap::attempt_allocation_slow() "
1029 "retries %d times", try_count);
1030 }
1031 }
1032
1033 ShouldNotReachHere();
1034 return NULL;
1035 }
1036
1037 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1038 unsigned int * gc_count_before_ret,
1039 int* gclocker_retry_count_ret) {
1040 // The structure of this method has a lot of similarities to
1041 // attempt_allocation_slow(). The reason these two were not merged
1042 // into a single one is that such a method would require several "if
1043 // allocation is not humongous do this, otherwise do that"
1044 // conditional paths which would obscure its flow. In fact, an early
1045 // version of this code did use a unified method which was harder to
1046 // follow and, as a result, it had subtle bugs that were hard to
1047 // track down. So keeping these two methods separate allows each to
1048 // be more readable. It will be good to keep these two in sync as
1049 // much as possible.
1050
1051 assert_heap_not_locked_and_not_at_safepoint();
1052 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1053 "should only be called for humongous allocations");
1054
1055 // Humongous objects can exhaust the heap quickly, so we should check if we
1056 // need to start a marking cycle at each humongous object allocation. We do
1057 // the check before we do the actual allocation. The reason for doing it
1058 // before the allocation is that we avoid having to keep track of the newly
1059 // allocated memory while we do a GC.
1060 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1061 word_size)) {
1062 collect(GCCause::_g1_humongous_allocation);
1063 }
1064
1065 // We will loop until a) we manage to successfully perform the
1066 // allocation or b) we successfully schedule a collection which
1067 // fails to perform the allocation. b) is the only case when we'll
1068 // return NULL.
1069 HeapWord* result = NULL;
1070 for (int try_count = 1; /* we'll return */; try_count += 1) {
1071 bool should_try_gc;
1072 unsigned int gc_count_before;
1073
1074 {
1075 MutexLockerEx x(Heap_lock);
1076
1077 // Given that humongous objects are not allocated in young
1078 // regions, we'll first try to do the allocation without doing a
1079 // collection hoping that there's enough space in the heap.
1080 result = humongous_obj_allocate(word_size);
1081 if (result != NULL) {
1082 return result;
1083 }
1084
1085 if (GC_locker::is_active_and_needs_gc()) {
1086 should_try_gc = false;
1087 } else {
1088 // The GCLocker may not be active but the GCLocker initiated
1089 // GC may not yet have been performed (GCLocker::needs_gc()
1090 // returns true). In this case we do not try this GC and
1091 // wait until the GCLocker initiated GC is performed, and
1092 // then retry the allocation.
1093 if (GC_locker::needs_gc()) {
1094 should_try_gc = false;
1095 } else {
1096 // Read the GC count while still holding the Heap_lock.
1097 gc_count_before = total_collections();
1098 should_try_gc = true;
1099 }
1100 }
1101 }
1102
1103 if (should_try_gc) {
1104 // If we failed to allocate the humongous object, we should try to
1105 // do a collection pause (if we're allowed) in case it reclaims
1106 // enough space for the allocation to succeed after the pause.
1107
1108 bool succeeded;
1109 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1110 if (result != NULL) {
1111 assert(succeeded, "only way to get back a non-NULL result");
1112 return result;
1113 }
1114
1115 if (succeeded) {
1116 // If we get here we successfully scheduled a collection which
1117 // failed to allocate. No point in trying to allocate
1118 // further. We'll just return NULL.
1119 MutexLockerEx x(Heap_lock);
1120 *gc_count_before_ret = total_collections();
1121 return NULL;
1122 }
1123 } else {
1124 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1125 MutexLockerEx x(Heap_lock);
1126 *gc_count_before_ret = total_collections();
1127 return NULL;
1128 }
1129 // The GCLocker is either active or the GCLocker initiated
1130 // GC has not yet been performed. Stall until it is and
1131 // then retry the allocation.
1132 GC_locker::stall_until_clear();
1133 (*gclocker_retry_count_ret) += 1;
1134 }
1135
1136 // We can reach here if we were unsuccessful in scheduling a
1137 // collection (because another thread beat us to it) or if we were
1138 // stalled due to the GC locker. In either can we should retry the
1139 // allocation attempt in case another thread successfully
1140 // performed a collection and reclaimed enough space. Give a
1141 // warning if we seem to be looping forever.
1142
1143 if ((QueuedAllocationWarningCount > 0) &&
1144 (try_count % QueuedAllocationWarningCount == 0)) {
1145 warning("G1CollectedHeap::attempt_allocation_humongous() "
1146 "retries %d times", try_count);
1147 }
1148 }
1149
1150 ShouldNotReachHere();
1151 return NULL;
1152 }
1153
1154 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1155 bool expect_null_mutator_alloc_region) {
1156 assert_at_safepoint(true /* should_be_vm_thread */);
1157 assert(_mutator_alloc_region.get() == NULL ||
1158 !expect_null_mutator_alloc_region,
1159 "the current alloc region was unexpectedly found to be non-NULL");
1160
1161 if (!isHumongous(word_size)) {
1162 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1163 false /* bot_updates */);
1164 } else {
1165 HeapWord* result = humongous_obj_allocate(word_size);
1166 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1167 g1_policy()->set_initiate_conc_mark_if_possible();
1168 }
1169 return result;
1170 }
1171
1172 ShouldNotReachHere();
1173 }
1174
1175 class PostMCRemSetClearClosure: public HeapRegionClosure {
1176 G1CollectedHeap* _g1h;
1177 ModRefBarrierSet* _mr_bs;
1178 public:
1179 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1180 _g1h(g1h), _mr_bs(mr_bs) { }
1181 bool doHeapRegion(HeapRegion* r) {
1182 if (r->continuesHumongous()) {
1183 return false;
1184 }
1185 _g1h->reset_gc_time_stamps(r);
1186 HeapRegionRemSet* hrrs = r->rem_set();
1187 if (hrrs != NULL) hrrs->clear();
1188 // You might think here that we could clear just the cards
1189 // corresponding to the used region. But no: if we leave a dirty card
1190 // in a region we might allocate into, then it would prevent that card
1191 // from being enqueued, and cause it to be missed.
1192 // Re: the performance cost: we shouldn't be doing full GC anyway!
1193 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1194 return false;
1195 }
1196 };
1197
1198 void G1CollectedHeap::clear_rsets_post_compaction() {
1199 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1200 heap_region_iterate(&rs_clear);
1201 }
1202
1203 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1204 G1CollectedHeap* _g1h;
1205 UpdateRSOopClosure _cl;
1206 int _worker_i;
1207 public:
1208 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1209 _cl(g1->g1_rem_set(), worker_i),
1210 _worker_i(worker_i),
1211 _g1h(g1)
1212 { }
1213
1214 bool doHeapRegion(HeapRegion* r) {
1215 if (!r->continuesHumongous()) {
1216 _cl.set_from(r);
1217 r->oop_iterate(&_cl);
1218 }
1219 return false;
1220 }
1221 };
1222
1223 class ParRebuildRSTask: public AbstractGangTask {
1224 G1CollectedHeap* _g1;
1225 public:
1226 ParRebuildRSTask(G1CollectedHeap* g1)
1227 : AbstractGangTask("ParRebuildRSTask"),
1228 _g1(g1)
1229 { }
1230
1231 void work(uint worker_id) {
1232 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1233 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1234 _g1->workers()->active_workers(),
1235 HeapRegion::RebuildRSClaimValue);
1236 }
1237 };
1238
1239 class PostCompactionPrinterClosure: public HeapRegionClosure {
1240 private:
1241 G1HRPrinter* _hr_printer;
1242 public:
1243 bool doHeapRegion(HeapRegion* hr) {
1244 assert(!hr->is_young(), "not expecting to find young regions");
1245 // We only generate output for non-empty regions.
1246 if (!hr->is_empty()) {
1247 if (!hr->isHumongous()) {
1248 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1249 } else if (hr->startsHumongous()) {
1250 if (hr->region_num() == 1) {
1251 // single humongous region
1252 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1253 } else {
1254 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1255 }
1256 } else {
1257 assert(hr->continuesHumongous(), "only way to get here");
1258 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1259 }
1260 }
1261 return false;
1262 }
1263
1264 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1265 : _hr_printer(hr_printer) { }
1266 };
1267
1268 void G1CollectedHeap::print_hrs_post_compaction() {
1269 PostCompactionPrinterClosure cl(hr_printer());
1270 heap_region_iterate(&cl);
1271 }
1272
1273 double G1CollectedHeap::verify(bool guard, const char* msg) {
1274 double verify_time_ms = 0.0;
1275
1276 if (guard && total_collections() >= VerifyGCStartAt) {
1277 double verify_start = os::elapsedTime();
1278 HandleMark hm; // Discard invalid handles created during verification
1279 prepare_for_verify();
1280 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
1281 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
1282 }
1283
1284 return verify_time_ms;
1285 }
1286
1287 void G1CollectedHeap::verify_before_gc() {
1288 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
1289 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
1290 }
1291
1292 void G1CollectedHeap::verify_after_gc() {
1293 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
1294 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
1295 }
1296
1297 bool G1CollectedHeap::do_collection(bool explicit_gc,
1298 bool clear_all_soft_refs,
1299 size_t word_size) {
1300 assert_at_safepoint(true /* should_be_vm_thread */);
1301
1302 if (GC_locker::check_active_before_gc()) {
1303 return false;
1304 }
1305
1306 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1307 gc_timer->register_gc_start(os::elapsed_counter());
1308
1309 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1310 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1311
1312 SvcGCMarker sgcm(SvcGCMarker::FULL);
1313 ResourceMark rm;
1314
1315 print_heap_before_gc();
1316 trace_heap_before_gc(gc_tracer);
1317
1318 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1319
1320 HRSPhaseSetter x(HRSPhaseFullGC);
1321 verify_region_sets_optional();
1322
1323 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1324 collector_policy()->should_clear_all_soft_refs();
1325
1326 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1327
1328 {
1329 IsGCActiveMark x;
1330
1331 // Timing
1332 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1333 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1334 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1335
1336 {
1337 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1338 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1339 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1340
1341 double start = os::elapsedTime();
1342 g1_policy()->record_full_collection_start();
1343
1344 // Note: When we have a more flexible GC logging framework that
1345 // allows us to add optional attributes to a GC log record we
1346 // could consider timing and reporting how long we wait in the
1347 // following two methods.
1348 wait_while_free_regions_coming();
1349 // If we start the compaction before the CM threads finish
1350 // scanning the root regions we might trip them over as we'll
1351 // be moving objects / updating references. So let's wait until
1352 // they are done. By telling them to abort, they should complete
1353 // early.
1354 _cm->root_regions()->abort();
1355 _cm->root_regions()->wait_until_scan_finished();
1356 append_secondary_free_list_if_not_empty_with_lock();
1357
1358 gc_prologue(true);
1359 increment_total_collections(true /* full gc */);
1360 increment_old_marking_cycles_started();
1361
1362 assert(used() == recalculate_used(), "Should be equal");
1363
1364 verify_before_gc();
1365
1366 pre_full_gc_dump(gc_timer);
1367
1368 COMPILER2_PRESENT(DerivedPointerTable::clear());
1369
1370 // Disable discovery and empty the discovered lists
1371 // for the CM ref processor.
1372 ref_processor_cm()->disable_discovery();
1373 ref_processor_cm()->abandon_partial_discovery();
1374 ref_processor_cm()->verify_no_references_recorded();
1375
1376 // Abandon current iterations of concurrent marking and concurrent
1377 // refinement, if any are in progress. We have to do this before
1378 // wait_until_scan_finished() below.
1379 concurrent_mark()->abort();
1380
1381 // Make sure we'll choose a new allocation region afterwards.
1382 release_mutator_alloc_region();
1383 abandon_gc_alloc_regions();
1384 g1_rem_set()->cleanupHRRS();
1385
1386 // We should call this after we retire any currently active alloc
1387 // regions so that all the ALLOC / RETIRE events are generated
1388 // before the start GC event.
1389 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1390
1391 // We may have added regions to the current incremental collection
1392 // set between the last GC or pause and now. We need to clear the
1393 // incremental collection set and then start rebuilding it afresh
1394 // after this full GC.
1395 abandon_collection_set(g1_policy()->inc_cset_head());
1396 g1_policy()->clear_incremental_cset();
1397 g1_policy()->stop_incremental_cset_building();
1398
1399 tear_down_region_sets(false /* free_list_only */);
1400 g1_policy()->set_gcs_are_young(true);
1401
1402 // See the comments in g1CollectedHeap.hpp and
1403 // G1CollectedHeap::ref_processing_init() about
1404 // how reference processing currently works in G1.
1405
1406 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1407 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1408
1409 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1410 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1411
1412 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1413 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1414
1415 // Do collection work
1416 {
1417 HandleMark hm; // Discard invalid handles created during gc
1418 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1419 }
1420
1421 assert(free_regions() == 0, "we should not have added any free regions");
1422 rebuild_region_sets(false /* free_list_only */);
1423
1424 // Enqueue any discovered reference objects that have
1425 // not been removed from the discovered lists.
1426 ref_processor_stw()->enqueue_discovered_references();
1427
1428 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1429
1430 MemoryService::track_memory_usage();
1431
1432 verify_after_gc();
1433
1434 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1435 ref_processor_stw()->verify_no_references_recorded();
1436
1437 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1438 ClassLoaderDataGraph::purge();
1439 MetaspaceAux::verify_metrics();
1440
1441 // Note: since we've just done a full GC, concurrent
1442 // marking is no longer active. Therefore we need not
1443 // re-enable reference discovery for the CM ref processor.
1444 // That will be done at the start of the next marking cycle.
1445 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1446 ref_processor_cm()->verify_no_references_recorded();
1447
1448 reset_gc_time_stamp();
1449 // Since everything potentially moved, we will clear all remembered
1450 // sets, and clear all cards. Later we will rebuild remembered
1451 // sets. We will also reset the GC time stamps of the regions.
1452 clear_rsets_post_compaction();
1453 check_gc_time_stamps();
1454
1455 // Resize the heap if necessary.
1456 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1457
1458 if (_hr_printer.is_active()) {
1459 // We should do this after we potentially resize the heap so
1460 // that all the COMMIT / UNCOMMIT events are generated before
1461 // the end GC event.
1462
1463 print_hrs_post_compaction();
1464 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1465 }
1466
1467 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1468 if (hot_card_cache->use_cache()) {
1469 hot_card_cache->reset_card_counts();
1470 hot_card_cache->reset_hot_cache();
1471 }
1472
1473 // Rebuild remembered sets of all regions.
1474 if (G1CollectedHeap::use_parallel_gc_threads()) {
1475 uint n_workers =
1476 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1477 workers()->active_workers(),
1478 Threads::number_of_non_daemon_threads());
1479 assert(UseDynamicNumberOfGCThreads ||
1480 n_workers == workers()->total_workers(),
1481 "If not dynamic should be using all the workers");
1482 workers()->set_active_workers(n_workers);
1483 // Set parallel threads in the heap (_n_par_threads) only
1484 // before a parallel phase and always reset it to 0 after
1485 // the phase so that the number of parallel threads does
1486 // no get carried forward to a serial phase where there
1487 // may be code that is "possibly_parallel".
1488 set_par_threads(n_workers);
1489
1490 ParRebuildRSTask rebuild_rs_task(this);
1491 assert(check_heap_region_claim_values(
1492 HeapRegion::InitialClaimValue), "sanity check");
1493 assert(UseDynamicNumberOfGCThreads ||
1494 workers()->active_workers() == workers()->total_workers(),
1495 "Unless dynamic should use total workers");
1496 // Use the most recent number of active workers
1497 assert(workers()->active_workers() > 0,
1498 "Active workers not properly set");
1499 set_par_threads(workers()->active_workers());
1500 workers()->run_task(&rebuild_rs_task);
1501 set_par_threads(0);
1502 assert(check_heap_region_claim_values(
1503 HeapRegion::RebuildRSClaimValue), "sanity check");
1504 reset_heap_region_claim_values();
1505 } else {
1506 RebuildRSOutOfRegionClosure rebuild_rs(this);
1507 heap_region_iterate(&rebuild_rs);
1508 }
1509
1510 if (true) { // FIXME
1511 MetaspaceGC::compute_new_size();
1512 }
1513
1514 #ifdef TRACESPINNING
1515 ParallelTaskTerminator::print_termination_counts();
1516 #endif
1517
1518 // Discard all rset updates
1519 JavaThread::dirty_card_queue_set().abandon_logs();
1520 assert(!G1DeferredRSUpdate
1521 || (G1DeferredRSUpdate &&
1522 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1523
1524 _young_list->reset_sampled_info();
1525 // At this point there should be no regions in the
1526 // entire heap tagged as young.
1527 assert(check_young_list_empty(true /* check_heap */),
1528 "young list should be empty at this point");
1529
1530 // Update the number of full collections that have been completed.
1531 increment_old_marking_cycles_completed(false /* concurrent */);
1532
1533 _hrs.verify_optional();
1534 verify_region_sets_optional();
1535
1536 // Start a new incremental collection set for the next pause
1537 assert(g1_policy()->collection_set() == NULL, "must be");
1538 g1_policy()->start_incremental_cset_building();
1539
1540 // Clear the _cset_fast_test bitmap in anticipation of adding
1541 // regions to the incremental collection set for the next
1542 // evacuation pause.
1543 clear_cset_fast_test();
1544
1545 init_mutator_alloc_region();
1546
1547 double end = os::elapsedTime();
1548 g1_policy()->record_full_collection_end();
1549
1550 if (G1Log::fine()) {
1551 g1_policy()->print_heap_transition();
1552 }
1553
1554 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1555 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1556 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1557 // before any GC notifications are raised.
1558 g1mm()->update_sizes();
1559
1560 gc_epilogue(true);
1561 }
1562
1563 if (G1Log::finer()) {
1564 g1_policy()->print_detailed_heap_transition(true /* full */);
1565 }
1566
1567 print_heap_after_gc();
1568 trace_heap_after_gc(gc_tracer);
1569
1570 post_full_gc_dump(gc_timer);
1571
1572 gc_timer->register_gc_end(os::elapsed_counter());
1573 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1574 }
1575
1576 return true;
1577 }
1578
1579 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1580 // do_collection() will return whether it succeeded in performing
1581 // the GC. Currently, there is no facility on the
1582 // do_full_collection() API to notify the caller than the collection
1583 // did not succeed (e.g., because it was locked out by the GC
1584 // locker). So, right now, we'll ignore the return value.
1585 bool dummy = do_collection(true, /* explicit_gc */
1586 clear_all_soft_refs,
1587 0 /* word_size */);
1588 }
1589
1590 // This code is mostly copied from TenuredGeneration.
1591 void
1592 G1CollectedHeap::
1593 resize_if_necessary_after_full_collection(size_t word_size) {
1594 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1595
1596 // Include the current allocation, if any, and bytes that will be
1597 // pre-allocated to support collections, as "used".
1598 const size_t used_after_gc = used();
1599 const size_t capacity_after_gc = capacity();
1600 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1601
1602 // This is enforced in arguments.cpp.
1603 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1604 "otherwise the code below doesn't make sense");
1605
1606 // We don't have floating point command-line arguments
1607 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1608 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1609 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1610 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1611
1612 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1613 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1614
1615 // We have to be careful here as these two calculations can overflow
1616 // 32-bit size_t's.
1617 double used_after_gc_d = (double) used_after_gc;
1618 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1619 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1620
1621 // Let's make sure that they are both under the max heap size, which
1622 // by default will make them fit into a size_t.
1623 double desired_capacity_upper_bound = (double) max_heap_size;
1624 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1625 desired_capacity_upper_bound);
1626 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1627 desired_capacity_upper_bound);
1628
1629 // We can now safely turn them into size_t's.
1630 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1631 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1632
1633 // This assert only makes sense here, before we adjust them
1634 // with respect to the min and max heap size.
1635 assert(minimum_desired_capacity <= maximum_desired_capacity,
1636 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1637 "maximum_desired_capacity = "SIZE_FORMAT,
1638 minimum_desired_capacity, maximum_desired_capacity));
1639
1640 // Should not be greater than the heap max size. No need to adjust
1641 // it with respect to the heap min size as it's a lower bound (i.e.,
1642 // we'll try to make the capacity larger than it, not smaller).
1643 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1644 // Should not be less than the heap min size. No need to adjust it
1645 // with respect to the heap max size as it's an upper bound (i.e.,
1646 // we'll try to make the capacity smaller than it, not greater).
1647 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1648
1649 if (capacity_after_gc < minimum_desired_capacity) {
1650 // Don't expand unless it's significant
1651 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1652 ergo_verbose4(ErgoHeapSizing,
1653 "attempt heap expansion",
1654 ergo_format_reason("capacity lower than "
1655 "min desired capacity after Full GC")
1656 ergo_format_byte("capacity")
1657 ergo_format_byte("occupancy")
1658 ergo_format_byte_perc("min desired capacity"),
1659 capacity_after_gc, used_after_gc,
1660 minimum_desired_capacity, (double) MinHeapFreeRatio);
1661 expand(expand_bytes);
1662
1663 // No expansion, now see if we want to shrink
1664 } else if (capacity_after_gc > maximum_desired_capacity) {
1665 // Capacity too large, compute shrinking size
1666 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1667 ergo_verbose4(ErgoHeapSizing,
1668 "attempt heap shrinking",
1669 ergo_format_reason("capacity higher than "
1670 "max desired capacity after Full GC")
1671 ergo_format_byte("capacity")
1672 ergo_format_byte("occupancy")
1673 ergo_format_byte_perc("max desired capacity"),
1674 capacity_after_gc, used_after_gc,
1675 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1676 shrink(shrink_bytes);
1677 }
1678 }
1679
1680
1681 HeapWord*
1682 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1683 bool* succeeded) {
1684 assert_at_safepoint(true /* should_be_vm_thread */);
1685
1686 *succeeded = true;
1687 // Let's attempt the allocation first.
1688 HeapWord* result =
1689 attempt_allocation_at_safepoint(word_size,
1690 false /* expect_null_mutator_alloc_region */);
1691 if (result != NULL) {
1692 assert(*succeeded, "sanity");
1693 return result;
1694 }
1695
1696 // In a G1 heap, we're supposed to keep allocation from failing by
1697 // incremental pauses. Therefore, at least for now, we'll favor
1698 // expansion over collection. (This might change in the future if we can
1699 // do something smarter than full collection to satisfy a failed alloc.)
1700 result = expand_and_allocate(word_size);
1701 if (result != NULL) {
1702 assert(*succeeded, "sanity");
1703 return result;
1704 }
1705
1706 // Expansion didn't work, we'll try to do a Full GC.
1707 bool gc_succeeded = do_collection(false, /* explicit_gc */
1708 false, /* clear_all_soft_refs */
1709 word_size);
1710 if (!gc_succeeded) {
1711 *succeeded = false;
1712 return NULL;
1713 }
1714
1715 // Retry the allocation
1716 result = attempt_allocation_at_safepoint(word_size,
1717 true /* expect_null_mutator_alloc_region */);
1718 if (result != NULL) {
1719 assert(*succeeded, "sanity");
1720 return result;
1721 }
1722
1723 // Then, try a Full GC that will collect all soft references.
1724 gc_succeeded = do_collection(false, /* explicit_gc */
1725 true, /* clear_all_soft_refs */
1726 word_size);
1727 if (!gc_succeeded) {
1728 *succeeded = false;
1729 return NULL;
1730 }
1731
1732 // Retry the allocation once more
1733 result = attempt_allocation_at_safepoint(word_size,
1734 true /* expect_null_mutator_alloc_region */);
1735 if (result != NULL) {
1736 assert(*succeeded, "sanity");
1737 return result;
1738 }
1739
1740 assert(!collector_policy()->should_clear_all_soft_refs(),
1741 "Flag should have been handled and cleared prior to this point");
1742
1743 // What else? We might try synchronous finalization later. If the total
1744 // space available is large enough for the allocation, then a more
1745 // complete compaction phase than we've tried so far might be
1746 // appropriate.
1747 assert(*succeeded, "sanity");
1748 return NULL;
1749 }
1750
1751 // Attempting to expand the heap sufficiently
1752 // to support an allocation of the given "word_size". If
1753 // successful, perform the allocation and return the address of the
1754 // allocated block, or else "NULL".
1755
1756 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1757 assert_at_safepoint(true /* should_be_vm_thread */);
1758
1759 verify_region_sets_optional();
1760
1761 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1762 ergo_verbose1(ErgoHeapSizing,
1763 "attempt heap expansion",
1764 ergo_format_reason("allocation request failed")
1765 ergo_format_byte("allocation request"),
1766 word_size * HeapWordSize);
1767 if (expand(expand_bytes)) {
1768 _hrs.verify_optional();
1769 verify_region_sets_optional();
1770 return attempt_allocation_at_safepoint(word_size,
1771 false /* expect_null_mutator_alloc_region */);
1772 }
1773 return NULL;
1774 }
1775
1776 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1777 HeapWord* new_end) {
1778 assert(old_end != new_end, "don't call this otherwise");
1779 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1780
1781 // Update the committed mem region.
1782 _g1_committed.set_end(new_end);
1783 // Tell the card table about the update.
1784 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1785 // Tell the BOT about the update.
1786 _bot_shared->resize(_g1_committed.word_size());
1787 // Tell the hot card cache about the update
1788 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1789 }
1790
1791 bool G1CollectedHeap::expand(size_t expand_bytes) {
1792 size_t old_mem_size = _g1_storage.committed_size();
1793 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1794 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1795 HeapRegion::GrainBytes);
1796 ergo_verbose2(ErgoHeapSizing,
1797 "expand the heap",
1798 ergo_format_byte("requested expansion amount")
1799 ergo_format_byte("attempted expansion amount"),
1800 expand_bytes, aligned_expand_bytes);
1801
1802 // First commit the memory.
1803 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1804 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1805 if (successful) {
1806 // Then propagate this update to the necessary data structures.
1807 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1808 update_committed_space(old_end, new_end);
1809
1810 FreeRegionList expansion_list("Local Expansion List");
1811 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1812 assert(mr.start() == old_end, "post-condition");
1813 // mr might be a smaller region than what was requested if
1814 // expand_by() was unable to allocate the HeapRegion instances
1815 assert(mr.end() <= new_end, "post-condition");
1816
1817 size_t actual_expand_bytes = mr.byte_size();
1818 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1819 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1820 "post-condition");
1821 if (actual_expand_bytes < aligned_expand_bytes) {
1822 // We could not expand _hrs to the desired size. In this case we
1823 // need to shrink the committed space accordingly.
1824 assert(mr.end() < new_end, "invariant");
1825
1826 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1827 // First uncommit the memory.
1828 _g1_storage.shrink_by(diff_bytes);
1829 // Then propagate this update to the necessary data structures.
1830 update_committed_space(new_end, mr.end());
1831 }
1832 _free_list.add_as_tail(&expansion_list);
1833
1834 if (_hr_printer.is_active()) {
1835 HeapWord* curr = mr.start();
1836 while (curr < mr.end()) {
1837 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1838 _hr_printer.commit(curr, curr_end);
1839 curr = curr_end;
1840 }
1841 assert(curr == mr.end(), "post-condition");
1842 }
1843 g1_policy()->record_new_heap_size(n_regions());
1844 } else {
1845 ergo_verbose0(ErgoHeapSizing,
1846 "did not expand the heap",
1847 ergo_format_reason("heap expansion operation failed"));
1848 // The expansion of the virtual storage space was unsuccessful.
1849 // Let's see if it was because we ran out of swap.
1850 if (G1ExitOnExpansionFailure &&
1851 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1852 // We had head room...
1853 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1854 }
1855 }
1856 return successful;
1857 }
1858
1859 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1860 size_t old_mem_size = _g1_storage.committed_size();
1861 size_t aligned_shrink_bytes =
1862 ReservedSpace::page_align_size_down(shrink_bytes);
1863 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1864 HeapRegion::GrainBytes);
1865 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1866
1867 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1868 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1869 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1870
1871 ergo_verbose3(ErgoHeapSizing,
1872 "shrink the heap",
1873 ergo_format_byte("requested shrinking amount")
1874 ergo_format_byte("aligned shrinking amount")
1875 ergo_format_byte("attempted shrinking amount"),
1876 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1877 if (num_regions_removed > 0) {
1878 _g1_storage.shrink_by(shrunk_bytes);
1879 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1880
1881 if (_hr_printer.is_active()) {
1882 HeapWord* curr = old_end;
1883 while (curr > new_end) {
1884 HeapWord* curr_end = curr;
1885 curr -= HeapRegion::GrainWords;
1886 _hr_printer.uncommit(curr, curr_end);
1887 }
1888 }
1889
1890 _expansion_regions += num_regions_removed;
1891 update_committed_space(old_end, new_end);
1892 HeapRegionRemSet::shrink_heap(n_regions());
1893 g1_policy()->record_new_heap_size(n_regions());
1894 } else {
1895 ergo_verbose0(ErgoHeapSizing,
1896 "did not shrink the heap",
1897 ergo_format_reason("heap shrinking operation failed"));
1898 }
1899 }
1900
1901 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1902 verify_region_sets_optional();
1903
1904 // We should only reach here at the end of a Full GC which means we
1905 // should not not be holding to any GC alloc regions. The method
1906 // below will make sure of that and do any remaining clean up.
1907 abandon_gc_alloc_regions();
1908
1909 // Instead of tearing down / rebuilding the free lists here, we
1910 // could instead use the remove_all_pending() method on free_list to
1911 // remove only the ones that we need to remove.
1912 tear_down_region_sets(true /* free_list_only */);
1913 shrink_helper(shrink_bytes);
1914 rebuild_region_sets(true /* free_list_only */);
1915
1916 _hrs.verify_optional();
1917 verify_region_sets_optional();
1918 }
1919
1920 // Public methods.
1921
1922 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1923 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1924 #endif // _MSC_VER
1925
1926
1927 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1928 SharedHeap(policy_),
1929 _g1_policy(policy_),
1930 _dirty_card_queue_set(false),
1931 _into_cset_dirty_card_queue_set(false),
1932 _is_alive_closure_cm(this),
1933 _is_alive_closure_stw(this),
1934 _ref_processor_cm(NULL),
1935 _ref_processor_stw(NULL),
1936 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1937 _bot_shared(NULL),
1938 _evac_failure_scan_stack(NULL),
1939 _mark_in_progress(false),
1940 _cg1r(NULL), _summary_bytes_used(0),
1941 _g1mm(NULL),
1942 _refine_cte_cl(NULL),
1943 _full_collection(false),
1944 _free_list("Master Free List"),
1945 _secondary_free_list("Secondary Free List"),
1946 _old_set("Old Set"),
1947 _humongous_set("Master Humongous Set"),
1948 _free_regions_coming(false),
1949 _young_list(new YoungList(this)),
1950 _gc_time_stamp(0),
1951 _retained_old_gc_alloc_region(NULL),
1952 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1953 _old_plab_stats(OldPLABSize, PLABWeight),
1954 _expand_heap_after_alloc_failure(true),
1955 _surviving_young_words(NULL),
1956 _old_marking_cycles_started(0),
1957 _old_marking_cycles_completed(0),
1958 _concurrent_cycle_started(false),
1959 _in_cset_fast_test(NULL),
1960 _in_cset_fast_test_base(NULL),
1961 _dirty_cards_region_list(NULL),
1962 _worker_cset_start_region(NULL),
1963 _worker_cset_start_region_time_stamp(NULL),
1964 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1965 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1966 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1967 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1968
1969 _g1h = this;
1970 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1971 vm_exit_during_initialization("Failed necessary allocation.");
1972 }
1973
1974 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1975
1976 int n_queues = MAX2((int)ParallelGCThreads, 1);
1977 _task_queues = new RefToScanQueueSet(n_queues);
1978
1979 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1980 assert(n_rem_sets > 0, "Invariant.");
1981
1982 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1983 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1984 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1985
1986 for (int i = 0; i < n_queues; i++) {
1987 RefToScanQueue* q = new RefToScanQueue();
1988 q->initialize();
1989 _task_queues->register_queue(i, q);
1990 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1991 }
1992 clear_cset_start_regions();
1993
1994 // Initialize the G1EvacuationFailureALot counters and flags.
1995 NOT_PRODUCT(reset_evacuation_should_fail();)
1996
1997 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1998 }
1999
2000 jint G1CollectedHeap::initialize() {
2001 CollectedHeap::pre_initialize();
2002 os::enable_vtime();
2003
2004 G1Log::init();
2005
2006 // Necessary to satisfy locking discipline assertions.
2007
2008 MutexLocker x(Heap_lock);
2009
2010 // We have to initialize the printer before committing the heap, as
2011 // it will be used then.
2012 _hr_printer.set_active(G1PrintHeapRegions);
2013
2014 // While there are no constraints in the GC code that HeapWordSize
2015 // be any particular value, there are multiple other areas in the
2016 // system which believe this to be true (e.g. oop->object_size in some
2017 // cases incorrectly returns the size in wordSize units rather than
2018 // HeapWordSize).
2019 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2020
2021 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2022 size_t max_byte_size = collector_policy()->max_heap_byte_size();
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
2028 _cg1r = new ConcurrentG1Refine(this);
2029
2030 // Reserve the maximum.
2031
2032 // When compressed oops are enabled, the preferred heap base
2033 // is calculated by subtracting the requested size from the
2034 // 32Gb boundary and using the result as the base address for
2035 // heap reservation. If the requested size is not aligned to
2036 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2037 // into the ReservedHeapSpace constructor) then the actual
2038 // base of the reserved heap may end up differing from the
2039 // address that was requested (i.e. the preferred heap base).
2040 // If this happens then we could end up using a non-optimal
2041 // compressed oops mode.
2042
2043 // Since max_byte_size is aligned to the size of a heap region (checked
2044 // above).
2045 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2046
2047 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2048 HeapRegion::GrainBytes);
2049
2050 // It is important to do this in a way such that concurrent readers can't
2051 // temporarily think something is in the heap. (I've actually seen this
2052 // happen in asserts: DLD.)
2053 _reserved.set_word_size(0);
2054 _reserved.set_start((HeapWord*)heap_rs.base());
2055 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2056
2057 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2058
2059 // Create the gen rem set (and barrier set) for the entire reserved region.
2060 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2061 set_barrier_set(rem_set()->bs());
2062 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2063 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2064 } else {
2065 vm_exit_during_initialization("G1 requires a mod ref bs.");
2066 return JNI_ENOMEM;
2067 }
2068
2069 // Also create a G1 rem set.
2070 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2071 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2072 } else {
2073 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2074 return JNI_ENOMEM;
2075 }
2076
2077 // Carve out the G1 part of the heap.
2078
2079 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2080 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2081 g1_rs.size()/HeapWordSize);
2082
2083 _g1_storage.initialize(g1_rs, 0);
2084 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2085 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2086 (HeapWord*) _g1_reserved.end(),
2087 _expansion_regions);
2088
2089 // Do later initialization work for concurrent refinement.
2090 _cg1r->init();
2091
2092 // 6843694 - ensure that the maximum region index can fit
2093 // in the remembered set structures.
2094 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2095 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2096
2097 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2098 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2099 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2100 "too many cards per region");
2101
2102 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2103
2104 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2105 heap_word_size(init_byte_size));
2106
2107 _g1h = this;
2108
2109 _in_cset_fast_test_length = max_regions();
2110 _in_cset_fast_test_base =
2111 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2112
2113 // We're biasing _in_cset_fast_test to avoid subtracting the
2114 // beginning of the heap every time we want to index; basically
2115 // it's the same with what we do with the card table.
2116 _in_cset_fast_test = _in_cset_fast_test_base -
2117 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2118
2119 // Clear the _cset_fast_test bitmap in anticipation of adding
2120 // regions to the incremental collection set for the first
2121 // evacuation pause.
2122 clear_cset_fast_test();
2123
2124 // Create the ConcurrentMark data structure and thread.
2125 // (Must do this late, so that "max_regions" is defined.)
2126 _cm = new ConcurrentMark(this, heap_rs);
2127 if (_cm == NULL || !_cm->completed_initialization()) {
2128 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2129 return JNI_ENOMEM;
2130 }
2131 _cmThread = _cm->cmThread();
2132
2133 // Initialize the from_card cache structure of HeapRegionRemSet.
2134 HeapRegionRemSet::init_heap(max_regions());
2135
2136 // Now expand into the initial heap size.
2137 if (!expand(init_byte_size)) {
2138 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2139 return JNI_ENOMEM;
2140 }
2141
2142 // Perform any initialization actions delegated to the policy.
2143 g1_policy()->init();
2144
2145 _refine_cte_cl =
2146 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2147 g1_rem_set(),
2148 concurrent_g1_refine());
2149 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2150
2151 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2152 SATB_Q_FL_lock,
2153 G1SATBProcessCompletedThreshold,
2154 Shared_SATB_Q_lock);
2155
2156 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2157 DirtyCardQ_FL_lock,
2158 concurrent_g1_refine()->yellow_zone(),
2159 concurrent_g1_refine()->red_zone(),
2160 Shared_DirtyCardQ_lock);
2161
2162 if (G1DeferredRSUpdate) {
2163 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2164 DirtyCardQ_FL_lock,
2165 -1, // never trigger processing
2166 -1, // no limit on length
2167 Shared_DirtyCardQ_lock,
2168 &JavaThread::dirty_card_queue_set());
2169 }
2170
2171 // Initialize the card queue set used to hold cards containing
2172 // references into the collection set.
2173 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2174 DirtyCardQ_FL_lock,
2175 -1, // never trigger processing
2176 -1, // no limit on length
2177 Shared_DirtyCardQ_lock,
2178 &JavaThread::dirty_card_queue_set());
2179
2180 // In case we're keeping closure specialization stats, initialize those
2181 // counts and that mechanism.
2182 SpecializationStats::clear();
2183
2184 // Here we allocate the dummy full region that is required by the
2185 // G1AllocRegion class. If we don't pass an address in the reserved
2186 // space here, lots of asserts fire.
2187
2188 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2189 _g1_reserved.start());
2190 // We'll re-use the same region whether the alloc region will
2191 // require BOT updates or not and, if it doesn't, then a non-young
2192 // region will complain that it cannot support allocations without
2193 // BOT updates. So we'll tag the dummy region as young to avoid that.
2194 dummy_region->set_young();
2195 // Make sure it's full.
2196 dummy_region->set_top(dummy_region->end());
2197 G1AllocRegion::setup(this, dummy_region);
2198
2199 init_mutator_alloc_region();
2200
2201 // Do create of the monitoring and management support so that
2202 // values in the heap have been properly initialized.
2203 _g1mm = new G1MonitoringSupport(this);
2204
2205 return JNI_OK;
2206 }
2207
2208 void G1CollectedHeap::ref_processing_init() {
2209 // Reference processing in G1 currently works as follows:
2210 //
2211 // * There are two reference processor instances. One is
2212 // used to record and process discovered references
2213 // during concurrent marking; the other is used to
2214 // record and process references during STW pauses
2215 // (both full and incremental).
2216 // * Both ref processors need to 'span' the entire heap as
2217 // the regions in the collection set may be dotted around.
2218 //
2219 // * For the concurrent marking ref processor:
2220 // * Reference discovery is enabled at initial marking.
2221 // * Reference discovery is disabled and the discovered
2222 // references processed etc during remarking.
2223 // * Reference discovery is MT (see below).
2224 // * Reference discovery requires a barrier (see below).
2225 // * Reference processing may or may not be MT
2226 // (depending on the value of ParallelRefProcEnabled
2227 // and ParallelGCThreads).
2228 // * A full GC disables reference discovery by the CM
2229 // ref processor and abandons any entries on it's
2230 // discovered lists.
2231 //
2232 // * For the STW processor:
2233 // * Non MT discovery is enabled at the start of a full GC.
2234 // * Processing and enqueueing during a full GC is non-MT.
2235 // * During a full GC, references are processed after marking.
2236 //
2237 // * Discovery (may or may not be MT) is enabled at the start
2238 // of an incremental evacuation pause.
2239 // * References are processed near the end of a STW evacuation pause.
2240 // * For both types of GC:
2241 // * Discovery is atomic - i.e. not concurrent.
2242 // * Reference discovery will not need a barrier.
2243
2244 SharedHeap::ref_processing_init();
2245 MemRegion mr = reserved_region();
2246
2247 // Concurrent Mark ref processor
2248 _ref_processor_cm =
2249 new ReferenceProcessor(mr, // span
2250 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2251 // mt processing
2252 (int) ParallelGCThreads,
2253 // degree of mt processing
2254 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2255 // mt discovery
2256 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2257 // degree of mt discovery
2258 false,
2259 // Reference discovery is not atomic
2260 &_is_alive_closure_cm,
2261 // is alive closure
2262 // (for efficiency/performance)
2263 true);
2264 // Setting next fields of discovered
2265 // lists requires a barrier.
2266
2267 // STW ref processor
2268 _ref_processor_stw =
2269 new ReferenceProcessor(mr, // span
2270 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2271 // mt processing
2272 MAX2((int)ParallelGCThreads, 1),
2273 // degree of mt processing
2274 (ParallelGCThreads > 1),
2275 // mt discovery
2276 MAX2((int)ParallelGCThreads, 1),
2277 // degree of mt discovery
2278 true,
2279 // Reference discovery is atomic
2280 &_is_alive_closure_stw,
2281 // is alive closure
2282 // (for efficiency/performance)
2283 false);
2284 // Setting next fields of discovered
2285 // lists requires a barrier.
2286 }
2287
2288 size_t G1CollectedHeap::capacity() const {
2289 return _g1_committed.byte_size();
2290 }
2291
2292 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2293 assert(!hr->continuesHumongous(), "pre-condition");
2294 hr->reset_gc_time_stamp();
2295 if (hr->startsHumongous()) {
2296 uint first_index = hr->hrs_index() + 1;
2297 uint last_index = hr->last_hc_index();
2298 for (uint i = first_index; i < last_index; i += 1) {
2299 HeapRegion* chr = region_at(i);
2300 assert(chr->continuesHumongous(), "sanity");
2301 chr->reset_gc_time_stamp();
2302 }
2303 }
2304 }
2305
2306 #ifndef PRODUCT
2307 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2308 private:
2309 unsigned _gc_time_stamp;
2310 bool _failures;
2311
2312 public:
2313 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2314 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2315
2316 virtual bool doHeapRegion(HeapRegion* hr) {
2317 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2318 if (_gc_time_stamp != region_gc_time_stamp) {
2319 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2320 "expected %d", HR_FORMAT_PARAMS(hr),
2321 region_gc_time_stamp, _gc_time_stamp);
2322 _failures = true;
2323 }
2324 return false;
2325 }
2326
2327 bool failures() { return _failures; }
2328 };
2329
2330 void G1CollectedHeap::check_gc_time_stamps() {
2331 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2332 heap_region_iterate(&cl);
2333 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2334 }
2335 #endif // PRODUCT
2336
2337 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2338 DirtyCardQueue* into_cset_dcq,
2339 bool concurrent,
2340 int worker_i) {
2341 // Clean cards in the hot card cache
2342 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2343 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2344
2345 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2346 int n_completed_buffers = 0;
2347 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2348 n_completed_buffers++;
2349 }
2350 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2351 dcqs.clear_n_completed_buffers();
2352 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2353 }
2354
2355
2356 // Computes the sum of the storage used by the various regions.
2357
2358 size_t G1CollectedHeap::used() const {
2359 assert(Heap_lock->owner() != NULL,
2360 "Should be owned on this thread's behalf.");
2361 size_t result = _summary_bytes_used;
2362 // Read only once in case it is set to NULL concurrently
2363 HeapRegion* hr = _mutator_alloc_region.get();
2364 if (hr != NULL)
2365 result += hr->used();
2366 return result;
2367 }
2368
2369 size_t G1CollectedHeap::used_unlocked() const {
2370 size_t result = _summary_bytes_used;
2371 return result;
2372 }
2373
2374 class SumUsedClosure: public HeapRegionClosure {
2375 size_t _used;
2376 public:
2377 SumUsedClosure() : _used(0) {}
2378 bool doHeapRegion(HeapRegion* r) {
2379 if (!r->continuesHumongous()) {
2380 _used += r->used();
2381 }
2382 return false;
2383 }
2384 size_t result() { return _used; }
2385 };
2386
2387 size_t G1CollectedHeap::recalculate_used() const {
2388 SumUsedClosure blk;
2389 heap_region_iterate(&blk);
2390 return blk.result();
2391 }
2392
2393 size_t G1CollectedHeap::unsafe_max_alloc() {
2394 if (free_regions() > 0) return HeapRegion::GrainBytes;
2395 // otherwise, is there space in the current allocation region?
2396
2397 // We need to store the current allocation region in a local variable
2398 // here. The problem is that this method doesn't take any locks and
2399 // there may be other threads which overwrite the current allocation
2400 // region field. attempt_allocation(), for example, sets it to NULL
2401 // and this can happen *after* the NULL check here but before the call
2402 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2403 // to be a problem in the optimized build, since the two loads of the
2404 // current allocation region field are optimized away.
2405 HeapRegion* hr = _mutator_alloc_region.get();
2406 if (hr == NULL) {
2407 return 0;
2408 }
2409 return hr->free();
2410 }
2411
2412 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2413 switch (cause) {
2414 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2415 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2416 case GCCause::_g1_humongous_allocation: return true;
2417 default: return false;
2418 }
2419 }
2420
2421 #ifndef PRODUCT
2422 void G1CollectedHeap::allocate_dummy_regions() {
2423 // Let's fill up most of the region
2424 size_t word_size = HeapRegion::GrainWords - 1024;
2425 // And as a result the region we'll allocate will be humongous.
2426 guarantee(isHumongous(word_size), "sanity");
2427
2428 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2429 // Let's use the existing mechanism for the allocation
2430 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2431 if (dummy_obj != NULL) {
2432 MemRegion mr(dummy_obj, word_size);
2433 CollectedHeap::fill_with_object(mr);
2434 } else {
2435 // If we can't allocate once, we probably cannot allocate
2436 // again. Let's get out of the loop.
2437 break;
2438 }
2439 }
2440 }
2441 #endif // !PRODUCT
2442
2443 void G1CollectedHeap::increment_old_marking_cycles_started() {
2444 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2445 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2446 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2447 _old_marking_cycles_started, _old_marking_cycles_completed));
2448
2449 _old_marking_cycles_started++;
2450 }
2451
2452 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2453 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2454
2455 // We assume that if concurrent == true, then the caller is a
2456 // concurrent thread that was joined the Suspendible Thread
2457 // Set. If there's ever a cheap way to check this, we should add an
2458 // assert here.
2459
2460 // Given that this method is called at the end of a Full GC or of a
2461 // concurrent cycle, and those can be nested (i.e., a Full GC can
2462 // interrupt a concurrent cycle), the number of full collections
2463 // completed should be either one (in the case where there was no
2464 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2465 // behind the number of full collections started.
2466
2467 // This is the case for the inner caller, i.e. a Full GC.
2468 assert(concurrent ||
2469 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2470 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2471 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2472 "is inconsistent with _old_marking_cycles_completed = %u",
2473 _old_marking_cycles_started, _old_marking_cycles_completed));
2474
2475 // This is the case for the outer caller, i.e. the concurrent cycle.
2476 assert(!concurrent ||
2477 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2478 err_msg("for outer caller (concurrent cycle): "
2479 "_old_marking_cycles_started = %u "
2480 "is inconsistent with _old_marking_cycles_completed = %u",
2481 _old_marking_cycles_started, _old_marking_cycles_completed));
2482
2483 _old_marking_cycles_completed += 1;
2484
2485 // We need to clear the "in_progress" flag in the CM thread before
2486 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2487 // is set) so that if a waiter requests another System.gc() it doesn't
2488 // incorrectly see that a marking cycle is still in progress.
2489 if (concurrent) {
2490 _cmThread->clear_in_progress();
2491 }
2492
2493 // This notify_all() will ensure that a thread that called
2494 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2495 // and it's waiting for a full GC to finish will be woken up. It is
2496 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2497 FullGCCount_lock->notify_all();
2498 }
2499
2500 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2501 _concurrent_cycle_started = true;
2502 _gc_timer_cm->register_gc_start(start_time);
2503
2504 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2505 trace_heap_before_gc(_gc_tracer_cm);
2506 }
2507
2508 void G1CollectedHeap::register_concurrent_cycle_end() {
2509 if (_concurrent_cycle_started) {
2510 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2511
2512 if (_cm->has_aborted()) {
2513 _gc_tracer_cm->report_concurrent_mode_failure();
2514 }
2515 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2516
2517 _concurrent_cycle_started = false;
2518 }
2519 }
2520
2521 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2522 if (_concurrent_cycle_started) {
2523 trace_heap_after_gc(_gc_tracer_cm);
2524 }
2525 }
2526
2527 G1YCType G1CollectedHeap::yc_type() {
2528 bool is_young = g1_policy()->gcs_are_young();
2529 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2530 bool is_during_mark = mark_in_progress();
2531
2532 if (is_initial_mark) {
2533 return InitialMark;
2534 } else if (is_during_mark) {
2535 return DuringMark;
2536 } else if (is_young) {
2537 return Normal;
2538 } else {
2539 return Mixed;
2540 }
2541 }
2542
2543 void G1CollectedHeap::collect(GCCause::Cause cause) {
2544 assert_heap_not_locked();
2545
2546 unsigned int gc_count_before;
2547 unsigned int old_marking_count_before;
2548 bool retry_gc;
2549
2550 do {
2551 retry_gc = false;
2552
2553 {
2554 MutexLocker ml(Heap_lock);
2555
2556 // Read the GC count while holding the Heap_lock
2557 gc_count_before = total_collections();
2558 old_marking_count_before = _old_marking_cycles_started;
2559 }
2560
2561 if (should_do_concurrent_full_gc(cause)) {
2562 // Schedule an initial-mark evacuation pause that will start a
2563 // concurrent cycle. We're setting word_size to 0 which means that
2564 // we are not requesting a post-GC allocation.
2565 VM_G1IncCollectionPause op(gc_count_before,
2566 0, /* word_size */
2567 true, /* should_initiate_conc_mark */
2568 g1_policy()->max_pause_time_ms(),
2569 cause);
2570
2571 VMThread::execute(&op);
2572 if (!op.pause_succeeded()) {
2573 if (old_marking_count_before == _old_marking_cycles_started) {
2574 retry_gc = op.should_retry_gc();
2575 } else {
2576 // A Full GC happened while we were trying to schedule the
2577 // initial-mark GC. No point in starting a new cycle given
2578 // that the whole heap was collected anyway.
2579 }
2580
2581 if (retry_gc) {
2582 if (GC_locker::is_active_and_needs_gc()) {
2583 GC_locker::stall_until_clear();
2584 }
2585 }
2586 }
2587 } else {
2588 if (cause == GCCause::_gc_locker
2589 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2590
2591 // Schedule a standard evacuation pause. We're setting word_size
2592 // to 0 which means that we are not requesting a post-GC allocation.
2593 VM_G1IncCollectionPause op(gc_count_before,
2594 0, /* word_size */
2595 false, /* should_initiate_conc_mark */
2596 g1_policy()->max_pause_time_ms(),
2597 cause);
2598 VMThread::execute(&op);
2599 } else {
2600 // Schedule a Full GC.
2601 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2602 VMThread::execute(&op);
2603 }
2604 }
2605 } while (retry_gc);
2606 }
2607
2608 bool G1CollectedHeap::is_in(const void* p) const {
2609 if (_g1_committed.contains(p)) {
2610 // Given that we know that p is in the committed space,
2611 // heap_region_containing_raw() should successfully
2612 // return the containing region.
2613 HeapRegion* hr = heap_region_containing_raw(p);
2614 return hr->is_in(p);
2615 } else {
2616 return false;
2617 }
2618 }
2619
2620 // Iteration functions.
2621
2622 // Iterates an OopClosure over all ref-containing fields of objects
2623 // within a HeapRegion.
2624
2625 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2626 MemRegion _mr;
2627 ExtendedOopClosure* _cl;
2628 public:
2629 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2630 : _mr(mr), _cl(cl) {}
2631 bool doHeapRegion(HeapRegion* r) {
2632 if (!r->continuesHumongous()) {
2633 r->oop_iterate(_cl);
2634 }
2635 return false;
2636 }
2637 };
2638
2639 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2640 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2641 heap_region_iterate(&blk);
2642 }
2643
2644 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2645 IterateOopClosureRegionClosure blk(mr, cl);
2646 heap_region_iterate(&blk);
2647 }
2648
2649 // Iterates an ObjectClosure over all objects within a HeapRegion.
2650
2651 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2652 ObjectClosure* _cl;
2653 public:
2654 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2655 bool doHeapRegion(HeapRegion* r) {
2656 if (! r->continuesHumongous()) {
2657 r->object_iterate(_cl);
2658 }
2659 return false;
2660 }
2661 };
2662
2663 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2664 IterateObjectClosureRegionClosure blk(cl);
2665 heap_region_iterate(&blk);
2666 }
2667
2668 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2669 // FIXME: is this right?
2670 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2671 }
2672
2673 // Calls a SpaceClosure on a HeapRegion.
2674
2675 class SpaceClosureRegionClosure: public HeapRegionClosure {
2676 SpaceClosure* _cl;
2677 public:
2678 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2679 bool doHeapRegion(HeapRegion* r) {
2680 _cl->do_space(r);
2681 return false;
2682 }
2683 };
2684
2685 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2686 SpaceClosureRegionClosure blk(cl);
2687 heap_region_iterate(&blk);
2688 }
2689
2690 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2691 _hrs.iterate(cl);
2692 }
2693
2694 void
2695 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2696 uint worker_id,
2697 uint no_of_par_workers,
2698 jint claim_value) {
2699 const uint regions = n_regions();
2700 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2701 no_of_par_workers :
2702 1);
2703 assert(UseDynamicNumberOfGCThreads ||
2704 no_of_par_workers == workers()->total_workers(),
2705 "Non dynamic should use fixed number of workers");
2706 // try to spread out the starting points of the workers
2707 const HeapRegion* start_hr =
2708 start_region_for_worker(worker_id, no_of_par_workers);
2709 const uint start_index = start_hr->hrs_index();
2710
2711 // each worker will actually look at all regions
2712 for (uint count = 0; count < regions; ++count) {
2713 const uint index = (start_index + count) % regions;
2714 assert(0 <= index && index < regions, "sanity");
2715 HeapRegion* r = region_at(index);
2716 // we'll ignore "continues humongous" regions (we'll process them
2717 // when we come across their corresponding "start humongous"
2718 // region) and regions already claimed
2719 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2720 continue;
2721 }
2722 // OK, try to claim it
2723 if (r->claimHeapRegion(claim_value)) {
2724 // success!
2725 assert(!r->continuesHumongous(), "sanity");
2726 if (r->startsHumongous()) {
2727 // If the region is "starts humongous" we'll iterate over its
2728 // "continues humongous" first; in fact we'll do them
2729 // first. The order is important. In on case, calling the
2730 // closure on the "starts humongous" region might de-allocate
2731 // and clear all its "continues humongous" regions and, as a
2732 // result, we might end up processing them twice. So, we'll do
2733 // them first (notice: most closures will ignore them anyway) and
2734 // then we'll do the "starts humongous" region.
2735 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2736 HeapRegion* chr = region_at(ch_index);
2737
2738 // if the region has already been claimed or it's not
2739 // "continues humongous" we're done
2740 if (chr->claim_value() == claim_value ||
2741 !chr->continuesHumongous()) {
2742 break;
2743 }
2744
2745 // No one should have claimed it directly. We can given
2746 // that we claimed its "starts humongous" region.
2747 assert(chr->claim_value() != claim_value, "sanity");
2748 assert(chr->humongous_start_region() == r, "sanity");
2749
2750 if (chr->claimHeapRegion(claim_value)) {
2751 // we should always be able to claim it; no one else should
2752 // be trying to claim this region
2753
2754 bool res2 = cl->doHeapRegion(chr);
2755 assert(!res2, "Should not abort");
2756
2757 // Right now, this holds (i.e., no closure that actually
2758 // does something with "continues humongous" regions
2759 // clears them). We might have to weaken it in the future,
2760 // but let's leave these two asserts here for extra safety.
2761 assert(chr->continuesHumongous(), "should still be the case");
2762 assert(chr->humongous_start_region() == r, "sanity");
2763 } else {
2764 guarantee(false, "we should not reach here");
2765 }
2766 }
2767 }
2768
2769 assert(!r->continuesHumongous(), "sanity");
2770 bool res = cl->doHeapRegion(r);
2771 assert(!res, "Should not abort");
2772 }
2773 }
2774 }
2775
2776 class ResetClaimValuesClosure: public HeapRegionClosure {
2777 public:
2778 bool doHeapRegion(HeapRegion* r) {
2779 r->set_claim_value(HeapRegion::InitialClaimValue);
2780 return false;
2781 }
2782 };
2783
2784 void G1CollectedHeap::reset_heap_region_claim_values() {
2785 ResetClaimValuesClosure blk;
2786 heap_region_iterate(&blk);
2787 }
2788
2789 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2790 ResetClaimValuesClosure blk;
2791 collection_set_iterate(&blk);
2792 }
2793
2794 #ifdef ASSERT
2795 // This checks whether all regions in the heap have the correct claim
2796 // value. I also piggy-backed on this a check to ensure that the
2797 // humongous_start_region() information on "continues humongous"
2798 // regions is correct.
2799
2800 class CheckClaimValuesClosure : public HeapRegionClosure {
2801 private:
2802 jint _claim_value;
2803 uint _failures;
2804 HeapRegion* _sh_region;
2805
2806 public:
2807 CheckClaimValuesClosure(jint claim_value) :
2808 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2809 bool doHeapRegion(HeapRegion* r) {
2810 if (r->claim_value() != _claim_value) {
2811 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2812 "claim value = %d, should be %d",
2813 HR_FORMAT_PARAMS(r),
2814 r->claim_value(), _claim_value);
2815 ++_failures;
2816 }
2817 if (!r->isHumongous()) {
2818 _sh_region = NULL;
2819 } else if (r->startsHumongous()) {
2820 _sh_region = r;
2821 } else if (r->continuesHumongous()) {
2822 if (r->humongous_start_region() != _sh_region) {
2823 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2824 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2825 HR_FORMAT_PARAMS(r),
2826 r->humongous_start_region(),
2827 _sh_region);
2828 ++_failures;
2829 }
2830 }
2831 return false;
2832 }
2833 uint failures() { return _failures; }
2834 };
2835
2836 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2837 CheckClaimValuesClosure cl(claim_value);
2838 heap_region_iterate(&cl);
2839 return cl.failures() == 0;
2840 }
2841
2842 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2843 private:
2844 jint _claim_value;
2845 uint _failures;
2846
2847 public:
2848 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2849 _claim_value(claim_value), _failures(0) { }
2850
2851 uint failures() { return _failures; }
2852
2853 bool doHeapRegion(HeapRegion* hr) {
2854 assert(hr->in_collection_set(), "how?");
2855 assert(!hr->isHumongous(), "H-region in CSet");
2856 if (hr->claim_value() != _claim_value) {
2857 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2858 "claim value = %d, should be %d",
2859 HR_FORMAT_PARAMS(hr),
2860 hr->claim_value(), _claim_value);
2861 _failures += 1;
2862 }
2863 return false;
2864 }
2865 };
2866
2867 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2868 CheckClaimValuesInCSetHRClosure cl(claim_value);
2869 collection_set_iterate(&cl);
2870 return cl.failures() == 0;
2871 }
2872 #endif // ASSERT
2873
2874 // Clear the cached CSet starting regions and (more importantly)
2875 // the time stamps. Called when we reset the GC time stamp.
2876 void G1CollectedHeap::clear_cset_start_regions() {
2877 assert(_worker_cset_start_region != NULL, "sanity");
2878 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2879
2880 int n_queues = MAX2((int)ParallelGCThreads, 1);
2881 for (int i = 0; i < n_queues; i++) {
2882 _worker_cset_start_region[i] = NULL;
2883 _worker_cset_start_region_time_stamp[i] = 0;
2884 }
2885 }
2886
2887 // Given the id of a worker, obtain or calculate a suitable
2888 // starting region for iterating over the current collection set.
2889 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2890 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2891
2892 HeapRegion* result = NULL;
2893 unsigned gc_time_stamp = get_gc_time_stamp();
2894
2895 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2896 // Cached starting region for current worker was set
2897 // during the current pause - so it's valid.
2898 // Note: the cached starting heap region may be NULL
2899 // (when the collection set is empty).
2900 result = _worker_cset_start_region[worker_i];
2901 assert(result == NULL || result->in_collection_set(), "sanity");
2902 return result;
2903 }
2904
2905 // The cached entry was not valid so let's calculate
2906 // a suitable starting heap region for this worker.
2907
2908 // We want the parallel threads to start their collection
2909 // set iteration at different collection set regions to
2910 // avoid contention.
2911 // If we have:
2912 // n collection set regions
2913 // p threads
2914 // Then thread t will start at region floor ((t * n) / p)
2915
2916 result = g1_policy()->collection_set();
2917 if (G1CollectedHeap::use_parallel_gc_threads()) {
2918 uint cs_size = g1_policy()->cset_region_length();
2919 uint active_workers = workers()->active_workers();
2920 assert(UseDynamicNumberOfGCThreads ||
2921 active_workers == workers()->total_workers(),
2922 "Unless dynamic should use total workers");
2923
2924 uint end_ind = (cs_size * worker_i) / active_workers;
2925 uint start_ind = 0;
2926
2927 if (worker_i > 0 &&
2928 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2929 // Previous workers starting region is valid
2930 // so let's iterate from there
2931 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2932 result = _worker_cset_start_region[worker_i - 1];
2933 }
2934
2935 for (uint i = start_ind; i < end_ind; i++) {
2936 result = result->next_in_collection_set();
2937 }
2938 }
2939
2940 // Note: the calculated starting heap region may be NULL
2941 // (when the collection set is empty).
2942 assert(result == NULL || result->in_collection_set(), "sanity");
2943 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2944 "should be updated only once per pause");
2945 _worker_cset_start_region[worker_i] = result;
2946 OrderAccess::storestore();
2947 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2948 return result;
2949 }
2950
2951 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2952 uint no_of_par_workers) {
2953 uint worker_num =
2954 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2955 assert(UseDynamicNumberOfGCThreads ||
2956 no_of_par_workers == workers()->total_workers(),
2957 "Non dynamic should use fixed number of workers");
2958 const uint start_index = n_regions() * worker_i / worker_num;
2959 return region_at(start_index);
2960 }
2961
2962 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2963 HeapRegion* r = g1_policy()->collection_set();
2964 while (r != NULL) {
2965 HeapRegion* next = r->next_in_collection_set();
2966 if (cl->doHeapRegion(r)) {
2967 cl->incomplete();
2968 return;
2969 }
2970 r = next;
2971 }
2972 }
2973
2974 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2975 HeapRegionClosure *cl) {
2976 if (r == NULL) {
2977 // The CSet is empty so there's nothing to do.
2978 return;
2979 }
2980
2981 assert(r->in_collection_set(),
2982 "Start region must be a member of the collection set.");
2983 HeapRegion* cur = r;
2984 while (cur != NULL) {
2985 HeapRegion* next = cur->next_in_collection_set();
2986 if (cl->doHeapRegion(cur) && false) {
2987 cl->incomplete();
2988 return;
2989 }
2990 cur = next;
2991 }
2992 cur = g1_policy()->collection_set();
2993 while (cur != r) {
2994 HeapRegion* next = cur->next_in_collection_set();
2995 if (cl->doHeapRegion(cur) && false) {
2996 cl->incomplete();
2997 return;
2998 }
2999 cur = next;
3000 }
3001 }
3002
3003 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
3004 return n_regions() > 0 ? region_at(0) : NULL;
3005 }
3006
3007
3008 Space* G1CollectedHeap::space_containing(const void* addr) const {
3009 Space* res = heap_region_containing(addr);
3010 return res;
3011 }
3012
3013 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
3014 Space* sp = space_containing(addr);
3015 if (sp != NULL) {
3016 return sp->block_start(addr);
3017 }
3018 return NULL;
3019 }
3020
3021 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3022 Space* sp = space_containing(addr);
3023 assert(sp != NULL, "block_size of address outside of heap");
3024 return sp->block_size(addr);
3025 }
3026
3027 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3028 Space* sp = space_containing(addr);
3029 return sp->block_is_obj(addr);
3030 }
3031
3032 bool G1CollectedHeap::supports_tlab_allocation() const {
3033 return true;
3034 }
3035
3036 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3037 return HeapRegion::GrainBytes;
3038 }
3039
3040 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3041 // Return the remaining space in the cur alloc region, but not less than
3042 // the min TLAB size.
3043
3044 // Also, this value can be at most the humongous object threshold,
3045 // since we can't allow tlabs to grow big enough to accommodate
3046 // humongous objects.
3047
3048 HeapRegion* hr = _mutator_alloc_region.get();
3049 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3050 if (hr == NULL) {
3051 return max_tlab_size;
3052 } else {
3053 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3054 }
3055 }
3056
3057 size_t G1CollectedHeap::max_capacity() const {
3058 return _g1_reserved.byte_size();
3059 }
3060
3061 jlong G1CollectedHeap::millis_since_last_gc() {
3062 // assert(false, "NYI");
3063 return 0;
3064 }
3065
3066 void G1CollectedHeap::prepare_for_verify() {
3067 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3068 ensure_parsability(false);
3069 }
3070 g1_rem_set()->prepare_for_verify();
3071 }
3072
3073 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3074 VerifyOption vo) {
3075 switch (vo) {
3076 case VerifyOption_G1UsePrevMarking:
3077 return hr->obj_allocated_since_prev_marking(obj);
3078 case VerifyOption_G1UseNextMarking:
3079 return hr->obj_allocated_since_next_marking(obj);
3080 case VerifyOption_G1UseMarkWord:
3081 return false;
3082 default:
3083 ShouldNotReachHere();
3084 }
3085 return false; // keep some compilers happy
3086 }
3087
3088 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3089 switch (vo) {
3090 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3091 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3092 case VerifyOption_G1UseMarkWord: return NULL;
3093 default: ShouldNotReachHere();
3094 }
3095 return NULL; // keep some compilers happy
3096 }
3097
3098 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3099 switch (vo) {
3100 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3101 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3102 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3103 default: ShouldNotReachHere();
3104 }
3105 return false; // keep some compilers happy
3106 }
3107
3108 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3109 switch (vo) {
3110 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3111 case VerifyOption_G1UseNextMarking: return "NTAMS";
3112 case VerifyOption_G1UseMarkWord: return "NONE";
3113 default: ShouldNotReachHere();
3114 }
3115 return NULL; // keep some compilers happy
3116 }
3117
3118 class VerifyLivenessOopClosure: public OopClosure {
3119 G1CollectedHeap* _g1h;
3120 VerifyOption _vo;
3121 public:
3122 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3123 _g1h(g1h), _vo(vo)
3124 { }
3125 void do_oop(narrowOop *p) { do_oop_work(p); }
3126 void do_oop( oop *p) { do_oop_work(p); }
3127
3128 template <class T> void do_oop_work(T *p) {
3129 oop obj = oopDesc::load_decode_heap_oop(p);
3130 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3131 "Dead object referenced by a not dead object");
3132 }
3133 };
3134
3135 class VerifyObjsInRegionClosure: public ObjectClosure {
3136 private:
3137 G1CollectedHeap* _g1h;
3138 size_t _live_bytes;
3139 HeapRegion *_hr;
3140 VerifyOption _vo;
3141 public:
3142 // _vo == UsePrevMarking -> use "prev" marking information,
3143 // _vo == UseNextMarking -> use "next" marking information,
3144 // _vo == UseMarkWord -> use mark word from object header.
3145 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3146 : _live_bytes(0), _hr(hr), _vo(vo) {
3147 _g1h = G1CollectedHeap::heap();
3148 }
3149 void do_object(oop o) {
3150 VerifyLivenessOopClosure isLive(_g1h, _vo);
3151 assert(o != NULL, "Huh?");
3152 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3153 // If the object is alive according to the mark word,
3154 // then verify that the marking information agrees.
3155 // Note we can't verify the contra-positive of the
3156 // above: if the object is dead (according to the mark
3157 // word), it may not be marked, or may have been marked
3158 // but has since became dead, or may have been allocated
3159 // since the last marking.
3160 if (_vo == VerifyOption_G1UseMarkWord) {
3161 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3162 }
3163
3164 o->oop_iterate_no_header(&isLive);
3165 if (!_hr->obj_allocated_since_prev_marking(o)) {
3166 size_t obj_size = o->size(); // Make sure we don't overflow
3167 _live_bytes += (obj_size * HeapWordSize);
3168 }
3169 }
3170 }
3171 size_t live_bytes() { return _live_bytes; }
3172 };
3173
3174 class PrintObjsInRegionClosure : public ObjectClosure {
3175 HeapRegion *_hr;
3176 G1CollectedHeap *_g1;
3177 public:
3178 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3179 _g1 = G1CollectedHeap::heap();
3180 };
3181
3182 void do_object(oop o) {
3183 if (o != NULL) {
3184 HeapWord *start = (HeapWord *) o;
3185 size_t word_sz = o->size();
3186 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3187 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3188 (void*) o, word_sz,
3189 _g1->isMarkedPrev(o),
3190 _g1->isMarkedNext(o),
3191 _hr->obj_allocated_since_prev_marking(o));
3192 HeapWord *end = start + word_sz;
3193 HeapWord *cur;
3194 int *val;
3195 for (cur = start; cur < end; cur++) {
3196 val = (int *) cur;
3197 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3198 }
3199 }
3200 }
3201 };
3202
3203 class VerifyRegionClosure: public HeapRegionClosure {
3204 private:
3205 bool _par;
3206 VerifyOption _vo;
3207 bool _failures;
3208 public:
3209 // _vo == UsePrevMarking -> use "prev" marking information,
3210 // _vo == UseNextMarking -> use "next" marking information,
3211 // _vo == UseMarkWord -> use mark word from object header.
3212 VerifyRegionClosure(bool par, VerifyOption vo)
3213 : _par(par),
3214 _vo(vo),
3215 _failures(false) {}
3216
3217 bool failures() {
3218 return _failures;
3219 }
3220
3221 bool doHeapRegion(HeapRegion* r) {
3222 if (!r->continuesHumongous()) {
3223 bool failures = false;
3224 r->verify(_vo, &failures);
3225 if (failures) {
3226 _failures = true;
3227 } else {
3228 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3229 r->object_iterate(¬_dead_yet_cl);
3230 if (_vo != VerifyOption_G1UseNextMarking) {
3231 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3232 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3233 "max_live_bytes "SIZE_FORMAT" "
3234 "< calculated "SIZE_FORMAT,
3235 r->bottom(), r->end(),
3236 r->max_live_bytes(),
3237 not_dead_yet_cl.live_bytes());
3238 _failures = true;
3239 }
3240 } else {
3241 // When vo == UseNextMarking we cannot currently do a sanity
3242 // check on the live bytes as the calculation has not been
3243 // finalized yet.
3244 }
3245 }
3246 }
3247 return false; // stop the region iteration if we hit a failure
3248 }
3249 };
3250
3251 class YoungRefCounterClosure : public OopClosure {
3252 G1CollectedHeap* _g1h;
3253 int _count;
3254 public:
3255 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3256 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3257 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3258
3259 int count() { return _count; }
3260 void reset_count() { _count = 0; };
3261 };
3262
3263 class VerifyKlassClosure: public KlassClosure {
3264 YoungRefCounterClosure _young_ref_counter_closure;
3265 OopClosure *_oop_closure;
3266 public:
3267 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3268 void do_klass(Klass* k) {
3269 k->oops_do(_oop_closure);
3270
3271 _young_ref_counter_closure.reset_count();
3272 k->oops_do(&_young_ref_counter_closure);
3273 if (_young_ref_counter_closure.count() > 0) {
3274 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3275 }
3276 }
3277 };
3278
3279 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3280 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3281 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3282 // we can change this closure to extend the simpler OopClosure.
3283 class VerifyRootsClosure: public OopsInGenClosure {
3284 private:
3285 G1CollectedHeap* _g1h;
3286 VerifyOption _vo;
3287 bool _failures;
3288 public:
3289 // _vo == UsePrevMarking -> use "prev" marking information,
3290 // _vo == UseNextMarking -> use "next" marking information,
3291 // _vo == UseMarkWord -> use mark word from object header.
3292 VerifyRootsClosure(VerifyOption vo) :
3293 _g1h(G1CollectedHeap::heap()),
3294 _vo(vo),
3295 _failures(false) { }
3296
3297 bool failures() { return _failures; }
3298
3299 template <class T> void do_oop_nv(T* p) {
3300 T heap_oop = oopDesc::load_heap_oop(p);
3301 if (!oopDesc::is_null(heap_oop)) {
3302 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3303 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3304 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3305 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3306 if (_vo == VerifyOption_G1UseMarkWord) {
3307 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3308 }
3309 obj->print_on(gclog_or_tty);
3310 _failures = true;
3311 }
3312 }
3313 }
3314
3315 void do_oop(oop* p) { do_oop_nv(p); }
3316 void do_oop(narrowOop* p) { do_oop_nv(p); }
3317 };
3318
3319 // This is the task used for parallel heap verification.
3320
3321 class G1ParVerifyTask: public AbstractGangTask {
3322 private:
3323 G1CollectedHeap* _g1h;
3324 VerifyOption _vo;
3325 bool _failures;
3326
3327 public:
3328 // _vo == UsePrevMarking -> use "prev" marking information,
3329 // _vo == UseNextMarking -> use "next" marking information,
3330 // _vo == UseMarkWord -> use mark word from object header.
3331 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3332 AbstractGangTask("Parallel verify task"),
3333 _g1h(g1h),
3334 _vo(vo),
3335 _failures(false) { }
3336
3337 bool failures() {
3338 return _failures;
3339 }
3340
3341 void work(uint worker_id) {
3342 HandleMark hm;
3343 VerifyRegionClosure blk(true, _vo);
3344 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3345 _g1h->workers()->active_workers(),
3346 HeapRegion::ParVerifyClaimValue);
3347 if (blk.failures()) {
3348 _failures = true;
3349 }
3350 }
3351 };
3352
3353 void G1CollectedHeap::verify(bool silent) {
3354 verify(silent, VerifyOption_G1UsePrevMarking);
3355 }
3356
3357 void G1CollectedHeap::verify(bool silent,
3358 VerifyOption vo) {
3359 if (SafepointSynchronize::is_at_safepoint()) {
3360 if (!silent) { gclog_or_tty->print("Roots "); }
3361 VerifyRootsClosure rootsCl(vo);
3362
3363 assert(Thread::current()->is_VM_thread(),
3364 "Expected to be executed serially by the VM thread at this point");
3365
3366 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3367 VerifyKlassClosure klassCl(this, &rootsCl);
3368
3369 // We apply the relevant closures to all the oops in the
3370 // system dictionary, the string table and the code cache.
3371 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3372
3373 // Need cleared claim bits for the strong roots processing
3374 ClassLoaderDataGraph::clear_claimed_marks();
3375
3376 process_strong_roots(true, // activate StrongRootsScope
3377 false, // we set "is scavenging" to false,
3378 // so we don't reset the dirty cards.
3379 ScanningOption(so), // roots scanning options
3380 &rootsCl,
3381 &blobsCl,
3382 &klassCl
3383 );
3384
3385 bool failures = rootsCl.failures();
3386
3387 if (vo != VerifyOption_G1UseMarkWord) {
3388 // If we're verifying during a full GC then the region sets
3389 // will have been torn down at the start of the GC. Therefore
3390 // verifying the region sets will fail. So we only verify
3391 // the region sets when not in a full GC.
3392 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3393 verify_region_sets();
3394 }
3395
3396 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3397 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3398 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3399 "sanity check");
3400
3401 G1ParVerifyTask task(this, vo);
3402 assert(UseDynamicNumberOfGCThreads ||
3403 workers()->active_workers() == workers()->total_workers(),
3404 "If not dynamic should be using all the workers");
3405 int n_workers = workers()->active_workers();
3406 set_par_threads(n_workers);
3407 workers()->run_task(&task);
3408 set_par_threads(0);
3409 if (task.failures()) {
3410 failures = true;
3411 }
3412
3413 // Checks that the expected amount of parallel work was done.
3414 // The implication is that n_workers is > 0.
3415 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3416 "sanity check");
3417
3418 reset_heap_region_claim_values();
3419
3420 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3421 "sanity check");
3422 } else {
3423 VerifyRegionClosure blk(false, vo);
3424 heap_region_iterate(&blk);
3425 if (blk.failures()) {
3426 failures = true;
3427 }
3428 }
3429 if (!silent) gclog_or_tty->print("RemSet ");
3430 rem_set()->verify();
3431
3432 if (failures) {
3433 gclog_or_tty->print_cr("Heap:");
3434 // It helps to have the per-region information in the output to
3435 // help us track down what went wrong. This is why we call
3436 // print_extended_on() instead of print_on().
3437 print_extended_on(gclog_or_tty);
3438 gclog_or_tty->print_cr("");
3439 #ifndef PRODUCT
3440 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3441 concurrent_mark()->print_reachable("at-verification-failure",
3442 vo, false /* all */);
3443 }
3444 #endif
3445 gclog_or_tty->flush();
3446 }
3447 guarantee(!failures, "there should not have been any failures");
3448 } else {
3449 if (!silent)
3450 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3451 }
3452 }
3453
3454 class PrintRegionClosure: public HeapRegionClosure {
3455 outputStream* _st;
3456 public:
3457 PrintRegionClosure(outputStream* st) : _st(st) {}
3458 bool doHeapRegion(HeapRegion* r) {
3459 r->print_on(_st);
3460 return false;
3461 }
3462 };
3463
3464 void G1CollectedHeap::print_on(outputStream* st) const {
3465 st->print(" %-20s", "garbage-first heap");
3466 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3467 capacity()/K, used_unlocked()/K);
3468 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3469 _g1_storage.low_boundary(),
3470 _g1_storage.high(),
3471 _g1_storage.high_boundary());
3472 st->cr();
3473 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3474 uint young_regions = _young_list->length();
3475 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3476 (size_t) young_regions * HeapRegion::GrainBytes / K);
3477 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3478 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3479 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3480 st->cr();
3481 MetaspaceAux::print_on(st);
3482 }
3483
3484 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3485 print_on(st);
3486
3487 // Print the per-region information.
3488 st->cr();
3489 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3490 "HS=humongous(starts), HC=humongous(continues), "
3491 "CS=collection set, F=free, TS=gc time stamp, "
3492 "PTAMS=previous top-at-mark-start, "
3493 "NTAMS=next top-at-mark-start)");
3494 PrintRegionClosure blk(st);
3495 heap_region_iterate(&blk);
3496 }
3497
3498 void G1CollectedHeap::print_on_error(outputStream* st) const {
3499 this->CollectedHeap::print_on_error(st);
3500
3501 if (_cm != NULL) {
3502 st->cr();
3503 _cm->print_on_error(st);
3504 }
3505 }
3506
3507 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3508 if (G1CollectedHeap::use_parallel_gc_threads()) {
3509 workers()->print_worker_threads_on(st);
3510 }
3511 _cmThread->print_on(st);
3512 st->cr();
3513 _cm->print_worker_threads_on(st);
3514 _cg1r->print_worker_threads_on(st);
3515 }
3516
3517 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3518 if (G1CollectedHeap::use_parallel_gc_threads()) {
3519 workers()->threads_do(tc);
3520 }
3521 tc->do_thread(_cmThread);
3522 _cg1r->threads_do(tc);
3523 }
3524
3525 void G1CollectedHeap::print_tracing_info() const {
3526 // We'll overload this to mean "trace GC pause statistics."
3527 if (TraceGen0Time || TraceGen1Time) {
3528 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3529 // to that.
3530 g1_policy()->print_tracing_info();
3531 }
3532 if (G1SummarizeRSetStats) {
3533 g1_rem_set()->print_summary_info();
3534 }
3535 if (G1SummarizeConcMark) {
3536 concurrent_mark()->print_summary_info();
3537 }
3538 g1_policy()->print_yg_surv_rate_info();
3539 SpecializationStats::print();
3540 }
3541
3542 #ifndef PRODUCT
3543 // Helpful for debugging RSet issues.
3544
3545 class PrintRSetsClosure : public HeapRegionClosure {
3546 private:
3547 const char* _msg;
3548 size_t _occupied_sum;
3549
3550 public:
3551 bool doHeapRegion(HeapRegion* r) {
3552 HeapRegionRemSet* hrrs = r->rem_set();
3553 size_t occupied = hrrs->occupied();
3554 _occupied_sum += occupied;
3555
3556 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3557 HR_FORMAT_PARAMS(r));
3558 if (occupied == 0) {
3559 gclog_or_tty->print_cr(" RSet is empty");
3560 } else {
3561 hrrs->print();
3562 }
3563 gclog_or_tty->print_cr("----------");
3564 return false;
3565 }
3566
3567 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3568 gclog_or_tty->cr();
3569 gclog_or_tty->print_cr("========================================");
3570 gclog_or_tty->print_cr(msg);
3571 gclog_or_tty->cr();
3572 }
3573
3574 ~PrintRSetsClosure() {
3575 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3576 gclog_or_tty->print_cr("========================================");
3577 gclog_or_tty->cr();
3578 }
3579 };
3580
3581 void G1CollectedHeap::print_cset_rsets() {
3582 PrintRSetsClosure cl("Printing CSet RSets");
3583 collection_set_iterate(&cl);
3584 }
3585
3586 void G1CollectedHeap::print_all_rsets() {
3587 PrintRSetsClosure cl("Printing All RSets");;
3588 heap_region_iterate(&cl);
3589 }
3590 #endif // PRODUCT
3591
3592 G1CollectedHeap* G1CollectedHeap::heap() {
3593 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3594 "not a garbage-first heap");
3595 return _g1h;
3596 }
3597
3598 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3599 // always_do_update_barrier = false;
3600 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3601 // Call allocation profiler
3602 AllocationProfiler::iterate_since_last_gc();
3603 // Fill TLAB's and such
3604 ensure_parsability(true);
3605 }
3606
3607 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3608 // FIXME: what is this about?
3609 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3610 // is set.
3611 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3612 "derived pointer present"));
3613 // always_do_update_barrier = true;
3614
3615 // We have just completed a GC. Update the soft reference
3616 // policy with the new heap occupancy
3617 Universe::update_heap_info_at_gc();
3618 }
3619
3620 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3621 unsigned int gc_count_before,
3622 bool* succeeded) {
3623 assert_heap_not_locked_and_not_at_safepoint();
3624 g1_policy()->record_stop_world_start();
3625 VM_G1IncCollectionPause op(gc_count_before,
3626 word_size,
3627 false, /* should_initiate_conc_mark */
3628 g1_policy()->max_pause_time_ms(),
3629 GCCause::_g1_inc_collection_pause);
3630 VMThread::execute(&op);
3631
3632 HeapWord* result = op.result();
3633 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3634 assert(result == NULL || ret_succeeded,
3635 "the result should be NULL if the VM did not succeed");
3636 *succeeded = ret_succeeded;
3637
3638 assert_heap_not_locked();
3639 return result;
3640 }
3641
3642 void
3643 G1CollectedHeap::doConcurrentMark() {
3644 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3645 if (!_cmThread->in_progress()) {
3646 _cmThread->set_started();
3647 CGC_lock->notify();
3648 }
3649 }
3650
3651 size_t G1CollectedHeap::pending_card_num() {
3652 size_t extra_cards = 0;
3653 JavaThread *curr = Threads::first();
3654 while (curr != NULL) {
3655 DirtyCardQueue& dcq = curr->dirty_card_queue();
3656 extra_cards += dcq.size();
3657 curr = curr->next();
3658 }
3659 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3660 size_t buffer_size = dcqs.buffer_size();
3661 size_t buffer_num = dcqs.completed_buffers_num();
3662
3663 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3664 // in bytes - not the number of 'entries'. We need to convert
3665 // into a number of cards.
3666 return (buffer_size * buffer_num + extra_cards) / oopSize;
3667 }
3668
3669 size_t G1CollectedHeap::cards_scanned() {
3670 return g1_rem_set()->cardsScanned();
3671 }
3672
3673 void
3674 G1CollectedHeap::setup_surviving_young_words() {
3675 assert(_surviving_young_words == NULL, "pre-condition");
3676 uint array_length = g1_policy()->young_cset_region_length();
3677 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3678 if (_surviving_young_words == NULL) {
3679 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3680 "Not enough space for young surv words summary.");
3681 }
3682 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3683 #ifdef ASSERT
3684 for (uint i = 0; i < array_length; ++i) {
3685 assert( _surviving_young_words[i] == 0, "memset above" );
3686 }
3687 #endif // !ASSERT
3688 }
3689
3690 void
3691 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3692 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3693 uint array_length = g1_policy()->young_cset_region_length();
3694 for (uint i = 0; i < array_length; ++i) {
3695 _surviving_young_words[i] += surv_young_words[i];
3696 }
3697 }
3698
3699 void
3700 G1CollectedHeap::cleanup_surviving_young_words() {
3701 guarantee( _surviving_young_words != NULL, "pre-condition" );
3702 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3703 _surviving_young_words = NULL;
3704 }
3705
3706 #ifdef ASSERT
3707 class VerifyCSetClosure: public HeapRegionClosure {
3708 public:
3709 bool doHeapRegion(HeapRegion* hr) {
3710 // Here we check that the CSet region's RSet is ready for parallel
3711 // iteration. The fields that we'll verify are only manipulated
3712 // when the region is part of a CSet and is collected. Afterwards,
3713 // we reset these fields when we clear the region's RSet (when the
3714 // region is freed) so they are ready when the region is
3715 // re-allocated. The only exception to this is if there's an
3716 // evacuation failure and instead of freeing the region we leave
3717 // it in the heap. In that case, we reset these fields during
3718 // evacuation failure handling.
3719 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3720
3721 // Here's a good place to add any other checks we'd like to
3722 // perform on CSet regions.
3723 return false;
3724 }
3725 };
3726 #endif // ASSERT
3727
3728 #if TASKQUEUE_STATS
3729 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3730 st->print_raw_cr("GC Task Stats");
3731 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3732 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3733 }
3734
3735 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3736 print_taskqueue_stats_hdr(st);
3737
3738 TaskQueueStats totals;
3739 const int n = workers() != NULL ? workers()->total_workers() : 1;
3740 for (int i = 0; i < n; ++i) {
3741 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3742 totals += task_queue(i)->stats;
3743 }
3744 st->print_raw("tot "); totals.print(st); st->cr();
3745
3746 DEBUG_ONLY(totals.verify());
3747 }
3748
3749 void G1CollectedHeap::reset_taskqueue_stats() {
3750 const int n = workers() != NULL ? workers()->total_workers() : 1;
3751 for (int i = 0; i < n; ++i) {
3752 task_queue(i)->stats.reset();
3753 }
3754 }
3755 #endif // TASKQUEUE_STATS
3756
3757 void G1CollectedHeap::log_gc_header() {
3758 if (!G1Log::fine()) {
3759 return;
3760 }
3761
3762 gclog_or_tty->date_stamp(PrintGCDateStamps);
3763 gclog_or_tty->stamp(PrintGCTimeStamps);
3764
3765 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3766 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3767 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3768
3769 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3770 }
3771
3772 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3773 if (!G1Log::fine()) {
3774 return;
3775 }
3776
3777 if (G1Log::finer()) {
3778 if (evacuation_failed()) {
3779 gclog_or_tty->print(" (to-space exhausted)");
3780 }
3781 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3782 g1_policy()->phase_times()->note_gc_end();
3783 g1_policy()->phase_times()->print(pause_time_sec);
3784 g1_policy()->print_detailed_heap_transition();
3785 } else {
3786 if (evacuation_failed()) {
3787 gclog_or_tty->print("--");
3788 }
3789 g1_policy()->print_heap_transition();
3790 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3791 }
3792 gclog_or_tty->flush();
3793 }
3794
3795 bool
3796 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3797 assert_at_safepoint(true /* should_be_vm_thread */);
3798 guarantee(!is_gc_active(), "collection is not reentrant");
3799
3800 if (GC_locker::check_active_before_gc()) {
3801 return false;
3802 }
3803
3804 _gc_timer_stw->register_gc_start(os::elapsed_counter());
3805
3806 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3807
3808 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3809 ResourceMark rm;
3810
3811 print_heap_before_gc();
3812 trace_heap_before_gc(_gc_tracer_stw);
3813
3814 HRSPhaseSetter x(HRSPhaseEvacuation);
3815 verify_region_sets_optional();
3816 verify_dirty_young_regions();
3817
3818 // This call will decide whether this pause is an initial-mark
3819 // pause. If it is, during_initial_mark_pause() will return true
3820 // for the duration of this pause.
3821 g1_policy()->decide_on_conc_mark_initiation();
3822
3823 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3824 assert(!g1_policy()->during_initial_mark_pause() ||
3825 g1_policy()->gcs_are_young(), "sanity");
3826
3827 // We also do not allow mixed GCs during marking.
3828 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3829
3830 // Record whether this pause is an initial mark. When the current
3831 // thread has completed its logging output and it's safe to signal
3832 // the CM thread, the flag's value in the policy has been reset.
3833 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3834
3835 // Inner scope for scope based logging, timers, and stats collection
3836 {
3837 EvacuationInfo evacuation_info;
3838
3839 if (g1_policy()->during_initial_mark_pause()) {
3840 // We are about to start a marking cycle, so we increment the
3841 // full collection counter.
3842 increment_old_marking_cycles_started();
3843 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3844 }
3845
3846 _gc_tracer_stw->report_yc_type(yc_type());
3847
3848 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3849
3850 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3851 workers()->active_workers() : 1);
3852 double pause_start_sec = os::elapsedTime();
3853 g1_policy()->phase_times()->note_gc_start(active_workers);
3854 log_gc_header();
3855
3856 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3857 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3858
3859 // If the secondary_free_list is not empty, append it to the
3860 // free_list. No need to wait for the cleanup operation to finish;
3861 // the region allocation code will check the secondary_free_list
3862 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3863 // set, skip this step so that the region allocation code has to
3864 // get entries from the secondary_free_list.
3865 if (!G1StressConcRegionFreeing) {
3866 append_secondary_free_list_if_not_empty_with_lock();
3867 }
3868
3869 assert(check_young_list_well_formed(),
3870 "young list should be well formed");
3871
3872 // Don't dynamically change the number of GC threads this early. A value of
3873 // 0 is used to indicate serial work. When parallel work is done,
3874 // it will be set.
3875
3876 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3877 IsGCActiveMark x;
3878
3879 gc_prologue(false);
3880 increment_total_collections(false /* full gc */);
3881 increment_gc_time_stamp();
3882
3883 verify_before_gc();
3884
3885 COMPILER2_PRESENT(DerivedPointerTable::clear());
3886
3887 // Please see comment in g1CollectedHeap.hpp and
3888 // G1CollectedHeap::ref_processing_init() to see how
3889 // reference processing currently works in G1.
3890
3891 // Enable discovery in the STW reference processor
3892 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3893 true /*verify_no_refs*/);
3894
3895 {
3896 // We want to temporarily turn off discovery by the
3897 // CM ref processor, if necessary, and turn it back on
3898 // on again later if we do. Using a scoped
3899 // NoRefDiscovery object will do this.
3900 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3901
3902 // Forget the current alloc region (we might even choose it to be part
3903 // of the collection set!).
3904 release_mutator_alloc_region();
3905
3906 // We should call this after we retire the mutator alloc
3907 // region(s) so that all the ALLOC / RETIRE events are generated
3908 // before the start GC event.
3909 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3910
3911 // This timing is only used by the ergonomics to handle our pause target.
3912 // It is unclear why this should not include the full pause. We will
3913 // investigate this in CR 7178365.
3914 //
3915 // Preserving the old comment here if that helps the investigation:
3916 //
3917 // The elapsed time induced by the start time below deliberately elides
3918 // the possible verification above.
3919 double sample_start_time_sec = os::elapsedTime();
3920
3921 #if YOUNG_LIST_VERBOSE
3922 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3923 _young_list->print();
3924 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3925 #endif // YOUNG_LIST_VERBOSE
3926
3927 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3928
3929 double scan_wait_start = os::elapsedTime();
3930 // We have to wait until the CM threads finish scanning the
3931 // root regions as it's the only way to ensure that all the
3932 // objects on them have been correctly scanned before we start
3933 // moving them during the GC.
3934 bool waited = _cm->root_regions()->wait_until_scan_finished();
3935 double wait_time_ms = 0.0;
3936 if (waited) {
3937 double scan_wait_end = os::elapsedTime();
3938 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3939 }
3940 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3941
3942 #if YOUNG_LIST_VERBOSE
3943 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3944 _young_list->print();
3945 #endif // YOUNG_LIST_VERBOSE
3946
3947 if (g1_policy()->during_initial_mark_pause()) {
3948 concurrent_mark()->checkpointRootsInitialPre();
3949 }
3950
3951 #if YOUNG_LIST_VERBOSE
3952 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3953 _young_list->print();
3954 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3955 #endif // YOUNG_LIST_VERBOSE
3956
3957 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3958
3959 _cm->note_start_of_gc();
3960 // We should not verify the per-thread SATB buffers given that
3961 // we have not filtered them yet (we'll do so during the
3962 // GC). We also call this after finalize_cset() to
3963 // ensure that the CSet has been finalized.
3964 _cm->verify_no_cset_oops(true /* verify_stacks */,
3965 true /* verify_enqueued_buffers */,
3966 false /* verify_thread_buffers */,
3967 true /* verify_fingers */);
3968
3969 if (_hr_printer.is_active()) {
3970 HeapRegion* hr = g1_policy()->collection_set();
3971 while (hr != NULL) {
3972 G1HRPrinter::RegionType type;
3973 if (!hr->is_young()) {
3974 type = G1HRPrinter::Old;
3975 } else if (hr->is_survivor()) {
3976 type = G1HRPrinter::Survivor;
3977 } else {
3978 type = G1HRPrinter::Eden;
3979 }
3980 _hr_printer.cset(hr);
3981 hr = hr->next_in_collection_set();
3982 }
3983 }
3984
3985 #ifdef ASSERT
3986 VerifyCSetClosure cl;
3987 collection_set_iterate(&cl);
3988 #endif // ASSERT
3989
3990 setup_surviving_young_words();
3991
3992 // Initialize the GC alloc regions.
3993 init_gc_alloc_regions(evacuation_info);
3994
3995 // Actually do the work...
3996 evacuate_collection_set(evacuation_info);
3997
3998 // We do this to mainly verify the per-thread SATB buffers
3999 // (which have been filtered by now) since we didn't verify
4000 // them earlier. No point in re-checking the stacks / enqueued
4001 // buffers given that the CSet has not changed since last time
4002 // we checked.
4003 _cm->verify_no_cset_oops(false /* verify_stacks */,
4004 false /* verify_enqueued_buffers */,
4005 true /* verify_thread_buffers */,
4006 true /* verify_fingers */);
4007
4008 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4009 g1_policy()->clear_collection_set();
4010
4011 cleanup_surviving_young_words();
4012
4013 // Start a new incremental collection set for the next pause.
4014 g1_policy()->start_incremental_cset_building();
4015
4016 // Clear the _cset_fast_test bitmap in anticipation of adding
4017 // regions to the incremental collection set for the next
4018 // evacuation pause.
4019 clear_cset_fast_test();
4020
4021 _young_list->reset_sampled_info();
4022
4023 // Don't check the whole heap at this point as the
4024 // GC alloc regions from this pause have been tagged
4025 // as survivors and moved on to the survivor list.
4026 // Survivor regions will fail the !is_young() check.
4027 assert(check_young_list_empty(false /* check_heap */),
4028 "young list should be empty");
4029
4030 #if YOUNG_LIST_VERBOSE
4031 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4032 _young_list->print();
4033 #endif // YOUNG_LIST_VERBOSE
4034
4035 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4036 _young_list->first_survivor_region(),
4037 _young_list->last_survivor_region());
4038
4039 _young_list->reset_auxilary_lists();
4040
4041 if (evacuation_failed()) {
4042 _summary_bytes_used = recalculate_used();
4043 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4044 for (uint i = 0; i < n_queues; i++) {
4045 if (_evacuation_failed_info_array[i].has_failed()) {
4046 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4047 }
4048 }
4049 } else {
4050 // The "used" of the the collection set have already been subtracted
4051 // when they were freed. Add in the bytes evacuated.
4052 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4053 }
4054
4055 if (g1_policy()->during_initial_mark_pause()) {
4056 // We have to do this before we notify the CM threads that
4057 // they can start working to make sure that all the
4058 // appropriate initialization is done on the CM object.
4059 concurrent_mark()->checkpointRootsInitialPost();
4060 set_marking_started();
4061 // Note that we don't actually trigger the CM thread at
4062 // this point. We do that later when we're sure that
4063 // the current thread has completed its logging output.
4064 }
4065
4066 allocate_dummy_regions();
4067
4068 #if YOUNG_LIST_VERBOSE
4069 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4070 _young_list->print();
4071 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4072 #endif // YOUNG_LIST_VERBOSE
4073
4074 init_mutator_alloc_region();
4075
4076 {
4077 size_t expand_bytes = g1_policy()->expansion_amount();
4078 if (expand_bytes > 0) {
4079 size_t bytes_before = capacity();
4080 // No need for an ergo verbose message here,
4081 // expansion_amount() does this when it returns a value > 0.
4082 if (!expand(expand_bytes)) {
4083 // We failed to expand the heap so let's verify that
4084 // committed/uncommitted amount match the backing store
4085 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4086 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4087 }
4088 }
4089 }
4090
4091 // We redo the verification but now wrt to the new CSet which
4092 // has just got initialized after the previous CSet was freed.
4093 _cm->verify_no_cset_oops(true /* verify_stacks */,
4094 true /* verify_enqueued_buffers */,
4095 true /* verify_thread_buffers */,
4096 true /* verify_fingers */);
4097 _cm->note_end_of_gc();
4098
4099 // This timing is only used by the ergonomics to handle our pause target.
4100 // It is unclear why this should not include the full pause. We will
4101 // investigate this in CR 7178365.
4102 double sample_end_time_sec = os::elapsedTime();
4103 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4104 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4105
4106 MemoryService::track_memory_usage();
4107
4108 // In prepare_for_verify() below we'll need to scan the deferred
4109 // update buffers to bring the RSets up-to-date if
4110 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4111 // the update buffers we'll probably need to scan cards on the
4112 // regions we just allocated to (i.e., the GC alloc
4113 // regions). However, during the last GC we called
4114 // set_saved_mark() on all the GC alloc regions, so card
4115 // scanning might skip the [saved_mark_word()...top()] area of
4116 // those regions (i.e., the area we allocated objects into
4117 // during the last GC). But it shouldn't. Given that
4118 // saved_mark_word() is conditional on whether the GC time stamp
4119 // on the region is current or not, by incrementing the GC time
4120 // stamp here we invalidate all the GC time stamps on all the
4121 // regions and saved_mark_word() will simply return top() for
4122 // all the regions. This is a nicer way of ensuring this rather
4123 // than iterating over the regions and fixing them. In fact, the
4124 // GC time stamp increment here also ensures that
4125 // saved_mark_word() will return top() between pauses, i.e.,
4126 // during concurrent refinement. So we don't need the
4127 // is_gc_active() check to decided which top to use when
4128 // scanning cards (see CR 7039627).
4129 increment_gc_time_stamp();
4130
4131 verify_after_gc();
4132
4133 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4134 ref_processor_stw()->verify_no_references_recorded();
4135
4136 // CM reference discovery will be re-enabled if necessary.
4137 }
4138
4139 // We should do this after we potentially expand the heap so
4140 // that all the COMMIT events are generated before the end GC
4141 // event, and after we retire the GC alloc regions so that all
4142 // RETIRE events are generated before the end GC event.
4143 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4144
4145 if (mark_in_progress()) {
4146 concurrent_mark()->update_g1_committed();
4147 }
4148
4149 #ifdef TRACESPINNING
4150 ParallelTaskTerminator::print_termination_counts();
4151 #endif
4152
4153 gc_epilogue(false);
4154 }
4155
4156 // Print the remainder of the GC log output.
4157 log_gc_footer(os::elapsedTime() - pause_start_sec);
4158
4159 // It is not yet to safe to tell the concurrent mark to
4160 // start as we have some optional output below. We don't want the
4161 // output from the concurrent mark thread interfering with this
4162 // logging output either.
4163
4164 _hrs.verify_optional();
4165 verify_region_sets_optional();
4166
4167 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4168 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4169
4170 print_heap_after_gc();
4171 trace_heap_after_gc(_gc_tracer_stw);
4172
4173 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4174 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4175 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4176 // before any GC notifications are raised.
4177 g1mm()->update_sizes();
4178
4179 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4180 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4181 _gc_timer_stw->register_gc_end(os::elapsed_counter());
4182 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4183 }
4184
4185 if (G1SummarizeRSetStats &&
4186 (G1SummarizeRSetStatsPeriod > 0) &&
4187 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
4188 g1_rem_set()->print_summary_info();
4189 }
4190 // It should now be safe to tell the concurrent mark thread to start
4191 // without its logging output interfering with the logging output
4192 // that came from the pause.
4193
4194 if (should_start_conc_mark) {
4195 // CAUTION: after the doConcurrentMark() call below,
4196 // the concurrent marking thread(s) could be running
4197 // concurrently with us. Make sure that anything after
4198 // this point does not assume that we are the only GC thread
4199 // running. Note: of course, the actual marking work will
4200 // not start until the safepoint itself is released in
4201 // ConcurrentGCThread::safepoint_desynchronize().
4202 doConcurrentMark();
4203 }
4204
4205 return true;
4206 }
4207
4208 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4209 {
4210 size_t gclab_word_size;
4211 switch (purpose) {
4212 case GCAllocForSurvived:
4213 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4214 break;
4215 case GCAllocForTenured:
4216 gclab_word_size = _old_plab_stats.desired_plab_sz();
4217 break;
4218 default:
4219 assert(false, "unknown GCAllocPurpose");
4220 gclab_word_size = _old_plab_stats.desired_plab_sz();
4221 break;
4222 }
4223
4224 // Prevent humongous PLAB sizes for two reasons:
4225 // * PLABs are allocated using a similar paths as oops, but should
4226 // never be in a humongous region
4227 // * Allowing humongous PLABs needlessly churns the region free lists
4228 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4229 }
4230
4231 void G1CollectedHeap::init_mutator_alloc_region() {
4232 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4233 _mutator_alloc_region.init();
4234 }
4235
4236 void G1CollectedHeap::release_mutator_alloc_region() {
4237 _mutator_alloc_region.release();
4238 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4239 }
4240
4241 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4242 assert_at_safepoint(true /* should_be_vm_thread */);
4243
4244 _survivor_gc_alloc_region.init();
4245 _old_gc_alloc_region.init();
4246 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4247 _retained_old_gc_alloc_region = NULL;
4248
4249 // We will discard the current GC alloc region if:
4250 // a) it's in the collection set (it can happen!),
4251 // b) it's already full (no point in using it),
4252 // c) it's empty (this means that it was emptied during
4253 // a cleanup and it should be on the free list now), or
4254 // d) it's humongous (this means that it was emptied
4255 // during a cleanup and was added to the free list, but
4256 // has been subsequently used to allocate a humongous
4257 // object that may be less than the region size).
4258 if (retained_region != NULL &&
4259 !retained_region->in_collection_set() &&
4260 !(retained_region->top() == retained_region->end()) &&
4261 !retained_region->is_empty() &&
4262 !retained_region->isHumongous()) {
4263 retained_region->set_saved_mark();
4264 // The retained region was added to the old region set when it was
4265 // retired. We have to remove it now, since we don't allow regions
4266 // we allocate to in the region sets. We'll re-add it later, when
4267 // it's retired again.
4268 _old_set.remove(retained_region);
4269 bool during_im = g1_policy()->during_initial_mark_pause();
4270 retained_region->note_start_of_copying(during_im);
4271 _old_gc_alloc_region.set(retained_region);
4272 _hr_printer.reuse(retained_region);
4273 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4274 }
4275 }
4276
4277 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4278 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4279 _old_gc_alloc_region.count());
4280 _survivor_gc_alloc_region.release();
4281 // If we have an old GC alloc region to release, we'll save it in
4282 // _retained_old_gc_alloc_region. If we don't
4283 // _retained_old_gc_alloc_region will become NULL. This is what we
4284 // want either way so no reason to check explicitly for either
4285 // condition.
4286 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4287
4288 if (ResizePLAB) {
4289 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4290 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4291 }
4292 }
4293
4294 void G1CollectedHeap::abandon_gc_alloc_regions() {
4295 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4296 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4297 _retained_old_gc_alloc_region = NULL;
4298 }
4299
4300 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4301 _drain_in_progress = false;
4302 set_evac_failure_closure(cl);
4303 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4304 }
4305
4306 void G1CollectedHeap::finalize_for_evac_failure() {
4307 assert(_evac_failure_scan_stack != NULL &&
4308 _evac_failure_scan_stack->length() == 0,
4309 "Postcondition");
4310 assert(!_drain_in_progress, "Postcondition");
4311 delete _evac_failure_scan_stack;
4312 _evac_failure_scan_stack = NULL;
4313 }
4314
4315 void G1CollectedHeap::remove_self_forwarding_pointers() {
4316 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4317
4318 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4319
4320 if (G1CollectedHeap::use_parallel_gc_threads()) {
4321 set_par_threads();
4322 workers()->run_task(&rsfp_task);
4323 set_par_threads(0);
4324 } else {
4325 rsfp_task.work(0);
4326 }
4327
4328 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4329
4330 // Reset the claim values in the regions in the collection set.
4331 reset_cset_heap_region_claim_values();
4332
4333 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4334
4335 // Now restore saved marks, if any.
4336 assert(_objs_with_preserved_marks.size() ==
4337 _preserved_marks_of_objs.size(), "Both or none.");
4338 while (!_objs_with_preserved_marks.is_empty()) {
4339 oop obj = _objs_with_preserved_marks.pop();
4340 markOop m = _preserved_marks_of_objs.pop();
4341 obj->set_mark(m);
4342 }
4343 _objs_with_preserved_marks.clear(true);
4344 _preserved_marks_of_objs.clear(true);
4345 }
4346
4347 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4348 _evac_failure_scan_stack->push(obj);
4349 }
4350
4351 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4352 assert(_evac_failure_scan_stack != NULL, "precondition");
4353
4354 while (_evac_failure_scan_stack->length() > 0) {
4355 oop obj = _evac_failure_scan_stack->pop();
4356 _evac_failure_closure->set_region(heap_region_containing(obj));
4357 obj->oop_iterate_backwards(_evac_failure_closure);
4358 }
4359 }
4360
4361 oop
4362 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4363 oop old) {
4364 assert(obj_in_cs(old),
4365 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4366 (HeapWord*) old));
4367 markOop m = old->mark();
4368 oop forward_ptr = old->forward_to_atomic(old);
4369 if (forward_ptr == NULL) {
4370 // Forward-to-self succeeded.
4371 assert(_par_scan_state != NULL, "par scan state");
4372 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4373 uint queue_num = _par_scan_state->queue_num();
4374
4375 _evacuation_failed = true;
4376 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4377 if (_evac_failure_closure != cl) {
4378 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4379 assert(!_drain_in_progress,
4380 "Should only be true while someone holds the lock.");
4381 // Set the global evac-failure closure to the current thread's.
4382 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4383 set_evac_failure_closure(cl);
4384 // Now do the common part.
4385 handle_evacuation_failure_common(old, m);
4386 // Reset to NULL.
4387 set_evac_failure_closure(NULL);
4388 } else {
4389 // The lock is already held, and this is recursive.
4390 assert(_drain_in_progress, "This should only be the recursive case.");
4391 handle_evacuation_failure_common(old, m);
4392 }
4393 return old;
4394 } else {
4395 // Forward-to-self failed. Either someone else managed to allocate
4396 // space for this object (old != forward_ptr) or they beat us in
4397 // self-forwarding it (old == forward_ptr).
4398 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4399 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4400 "should not be in the CSet",
4401 (HeapWord*) old, (HeapWord*) forward_ptr));
4402 return forward_ptr;
4403 }
4404 }
4405
4406 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4407 preserve_mark_if_necessary(old, m);
4408
4409 HeapRegion* r = heap_region_containing(old);
4410 if (!r->evacuation_failed()) {
4411 r->set_evacuation_failed(true);
4412 _hr_printer.evac_failure(r);
4413 }
4414
4415 push_on_evac_failure_scan_stack(old);
4416
4417 if (!_drain_in_progress) {
4418 // prevent recursion in copy_to_survivor_space()
4419 _drain_in_progress = true;
4420 drain_evac_failure_scan_stack();
4421 _drain_in_progress = false;
4422 }
4423 }
4424
4425 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4426 assert(evacuation_failed(), "Oversaving!");
4427 // We want to call the "for_promotion_failure" version only in the
4428 // case of a promotion failure.
4429 if (m->must_be_preserved_for_promotion_failure(obj)) {
4430 _objs_with_preserved_marks.push(obj);
4431 _preserved_marks_of_objs.push(m);
4432 }
4433 }
4434
4435 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4436 size_t word_size) {
4437 if (purpose == GCAllocForSurvived) {
4438 HeapWord* result = survivor_attempt_allocation(word_size);
4439 if (result != NULL) {
4440 return result;
4441 } else {
4442 // Let's try to allocate in the old gen in case we can fit the
4443 // object there.
4444 return old_attempt_allocation(word_size);
4445 }
4446 } else {
4447 assert(purpose == GCAllocForTenured, "sanity");
4448 HeapWord* result = old_attempt_allocation(word_size);
4449 if (result != NULL) {
4450 return result;
4451 } else {
4452 // Let's try to allocate in the survivors in case we can fit the
4453 // object there.
4454 return survivor_attempt_allocation(word_size);
4455 }
4456 }
4457
4458 ShouldNotReachHere();
4459 // Trying to keep some compilers happy.
4460 return NULL;
4461 }
4462
4463 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4464 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4465
4466 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4467 : _g1h(g1h),
4468 _refs(g1h->task_queue(queue_num)),
4469 _dcq(&g1h->dirty_card_queue_set()),
4470 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4471 _g1_rem(g1h->g1_rem_set()),
4472 _hash_seed(17), _queue_num(queue_num),
4473 _term_attempts(0),
4474 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4475 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4476 _age_table(false),
4477 _strong_roots_time(0), _term_time(0),
4478 _alloc_buffer_waste(0), _undo_waste(0) {
4479 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4480 // we "sacrifice" entry 0 to keep track of surviving bytes for
4481 // non-young regions (where the age is -1)
4482 // We also add a few elements at the beginning and at the end in
4483 // an attempt to eliminate cache contention
4484 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4485 uint array_length = PADDING_ELEM_NUM +
4486 real_length +
4487 PADDING_ELEM_NUM;
4488 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4489 if (_surviving_young_words_base == NULL)
4490 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4491 "Not enough space for young surv histo.");
4492 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4493 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4494
4495 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4496 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4497
4498 _start = os::elapsedTime();
4499 }
4500
4501 void
4502 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4503 {
4504 st->print_raw_cr("GC Termination Stats");
4505 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4506 " ------waste (KiB)------");
4507 st->print_raw_cr("thr ms ms % ms % attempts"
4508 " total alloc undo");
4509 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4510 " ------- ------- -------");
4511 }
4512
4513 void
4514 G1ParScanThreadState::print_termination_stats(int i,
4515 outputStream* const st) const
4516 {
4517 const double elapsed_ms = elapsed_time() * 1000.0;
4518 const double s_roots_ms = strong_roots_time() * 1000.0;
4519 const double term_ms = term_time() * 1000.0;
4520 st->print_cr("%3d %9.2f %9.2f %6.2f "
4521 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4522 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4523 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4524 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4525 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4526 alloc_buffer_waste() * HeapWordSize / K,
4527 undo_waste() * HeapWordSize / K);
4528 }
4529
4530 #ifdef ASSERT
4531 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4532 assert(ref != NULL, "invariant");
4533 assert(UseCompressedOops, "sanity");
4534 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4535 oop p = oopDesc::load_decode_heap_oop(ref);
4536 assert(_g1h->is_in_g1_reserved(p),
4537 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4538 return true;
4539 }
4540
4541 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4542 assert(ref != NULL, "invariant");
4543 if (has_partial_array_mask(ref)) {
4544 // Must be in the collection set--it's already been copied.
4545 oop p = clear_partial_array_mask(ref);
4546 assert(_g1h->obj_in_cs(p),
4547 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4548 } else {
4549 oop p = oopDesc::load_decode_heap_oop(ref);
4550 assert(_g1h->is_in_g1_reserved(p),
4551 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4552 }
4553 return true;
4554 }
4555
4556 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4557 if (ref.is_narrow()) {
4558 return verify_ref((narrowOop*) ref);
4559 } else {
4560 return verify_ref((oop*) ref);
4561 }
4562 }
4563 #endif // ASSERT
4564
4565 void G1ParScanThreadState::trim_queue() {
4566 assert(_evac_cl != NULL, "not set");
4567 assert(_evac_failure_cl != NULL, "not set");
4568 assert(_partial_scan_cl != NULL, "not set");
4569
4570 StarTask ref;
4571 do {
4572 // Drain the overflow stack first, so other threads can steal.
4573 while (refs()->pop_overflow(ref)) {
4574 deal_with_reference(ref);
4575 }
4576
4577 while (refs()->pop_local(ref)) {
4578 deal_with_reference(ref);
4579 }
4580 } while (!refs()->is_empty());
4581 }
4582
4583 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4584 G1ParScanThreadState* par_scan_state) :
4585 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4586 _par_scan_state(par_scan_state),
4587 _worker_id(par_scan_state->queue_num()),
4588 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4589 _mark_in_progress(_g1->mark_in_progress()) { }
4590
4591 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4592 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4593 #ifdef ASSERT
4594 HeapRegion* hr = _g1->heap_region_containing(obj);
4595 assert(hr != NULL, "sanity");
4596 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4597 #endif // ASSERT
4598
4599 // We know that the object is not moving so it's safe to read its size.
4600 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4601 }
4602
4603 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4604 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4605 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4606 #ifdef ASSERT
4607 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4608 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4609 assert(from_obj != to_obj, "should not be self-forwarded");
4610
4611 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4612 assert(from_hr != NULL, "sanity");
4613 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4614
4615 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4616 assert(to_hr != NULL, "sanity");
4617 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4618 #endif // ASSERT
4619
4620 // The object might be in the process of being copied by another
4621 // worker so we cannot trust that its to-space image is
4622 // well-formed. So we have to read its size from its from-space
4623 // image which we know should not be changing.
4624 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4625 }
4626
4627 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4628 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4629 ::copy_to_survivor_space(oop old) {
4630 size_t word_sz = old->size();
4631 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4632 // +1 to make the -1 indexes valid...
4633 int young_index = from_region->young_index_in_cset()+1;
4634 assert( (from_region->is_young() && young_index > 0) ||
4635 (!from_region->is_young() && young_index == 0), "invariant" );
4636 G1CollectorPolicy* g1p = _g1->g1_policy();
4637 markOop m = old->mark();
4638 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4639 : m->age();
4640 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4641 word_sz);
4642 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4643 #ifndef PRODUCT
4644 // Should this evacuation fail?
4645 if (_g1->evacuation_should_fail()) {
4646 if (obj_ptr != NULL) {
4647 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4648 obj_ptr = NULL;
4649 }
4650 }
4651 #endif // !PRODUCT
4652
4653 if (obj_ptr == NULL) {
4654 // This will either forward-to-self, or detect that someone else has
4655 // installed a forwarding pointer.
4656 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4657 }
4658
4659 oop obj = oop(obj_ptr);
4660
4661 // We're going to allocate linearly, so might as well prefetch ahead.
4662 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4663
4664 oop forward_ptr = old->forward_to_atomic(obj);
4665 if (forward_ptr == NULL) {
4666 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4667 if (g1p->track_object_age(alloc_purpose)) {
4668 // We could simply do obj->incr_age(). However, this causes a
4669 // performance issue. obj->incr_age() will first check whether
4670 // the object has a displaced mark by checking its mark word;
4671 // getting the mark word from the new location of the object
4672 // stalls. So, given that we already have the mark word and we
4673 // are about to install it anyway, it's better to increase the
4674 // age on the mark word, when the object does not have a
4675 // displaced mark word. We're not expecting many objects to have
4676 // a displaced marked word, so that case is not optimized
4677 // further (it could be...) and we simply call obj->incr_age().
4678
4679 if (m->has_displaced_mark_helper()) {
4680 // in this case, we have to install the mark word first,
4681 // otherwise obj looks to be forwarded (the old mark word,
4682 // which contains the forward pointer, was copied)
4683 obj->set_mark(m);
4684 obj->incr_age();
4685 } else {
4686 m = m->incr_age();
4687 obj->set_mark(m);
4688 }
4689 _par_scan_state->age_table()->add(obj, word_sz);
4690 } else {
4691 obj->set_mark(m);
4692 }
4693
4694 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4695 surv_young_words[young_index] += word_sz;
4696
4697 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4698 // We keep track of the next start index in the length field of
4699 // the to-space object. The actual length can be found in the
4700 // length field of the from-space object.
4701 arrayOop(obj)->set_length(0);
4702 oop* old_p = set_partial_array_mask(old);
4703 _par_scan_state->push_on_queue(old_p);
4704 } else {
4705 // No point in using the slower heap_region_containing() method,
4706 // given that we know obj is in the heap.
4707 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4708 obj->oop_iterate_backwards(&_scanner);
4709 }
4710 } else {
4711 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4712 obj = forward_ptr;
4713 }
4714 return obj;
4715 }
4716
4717 template <class T>
4718 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4719 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4720 _scanned_klass->record_modified_oops();
4721 }
4722 }
4723
4724 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4725 template <class T>
4726 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4727 ::do_oop_work(T* p) {
4728 oop obj = oopDesc::load_decode_heap_oop(p);
4729 assert(barrier != G1BarrierRS || obj != NULL,
4730 "Precondition: G1BarrierRS implies obj is non-NULL");
4731
4732 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4733
4734 // here the null check is implicit in the cset_fast_test() test
4735 if (_g1->in_cset_fast_test(obj)) {
4736 oop forwardee;
4737 if (obj->is_forwarded()) {
4738 forwardee = obj->forwardee();
4739 } else {
4740 forwardee = copy_to_survivor_space(obj);
4741 }
4742 assert(forwardee != NULL, "forwardee should not be NULL");
4743 oopDesc::encode_store_heap_oop(p, forwardee);
4744 if (do_mark_object && forwardee != obj) {
4745 // If the object is self-forwarded we don't need to explicitly
4746 // mark it, the evacuation failure protocol will do so.
4747 mark_forwarded_object(obj, forwardee);
4748 }
4749
4750 // When scanning the RS, we only care about objs in CS.
4751 if (barrier == G1BarrierRS) {
4752 _par_scan_state->update_rs(_from, p, _worker_id);
4753 } else if (barrier == G1BarrierKlass) {
4754 do_klass_barrier(p, forwardee);
4755 }
4756 } else {
4757 // The object is not in collection set. If we're a root scanning
4758 // closure during an initial mark pause (i.e. do_mark_object will
4759 // be true) then attempt to mark the object.
4760 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4761 mark_object(obj);
4762 }
4763 }
4764
4765 if (barrier == G1BarrierEvac && obj != NULL) {
4766 _par_scan_state->update_rs(_from, p, _worker_id);
4767 }
4768
4769 if (do_gen_barrier && obj != NULL) {
4770 par_do_barrier(p);
4771 }
4772 }
4773
4774 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4775 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4776
4777 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4778 assert(has_partial_array_mask(p), "invariant");
4779 oop from_obj = clear_partial_array_mask(p);
4780
4781 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4782 assert(from_obj->is_objArray(), "must be obj array");
4783 objArrayOop from_obj_array = objArrayOop(from_obj);
4784 // The from-space object contains the real length.
4785 int length = from_obj_array->length();
4786
4787 assert(from_obj->is_forwarded(), "must be forwarded");
4788 oop to_obj = from_obj->forwardee();
4789 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4790 objArrayOop to_obj_array = objArrayOop(to_obj);
4791 // We keep track of the next start index in the length field of the
4792 // to-space object.
4793 int next_index = to_obj_array->length();
4794 assert(0 <= next_index && next_index < length,
4795 err_msg("invariant, next index: %d, length: %d", next_index, length));
4796
4797 int start = next_index;
4798 int end = length;
4799 int remainder = end - start;
4800 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4801 if (remainder > 2 * ParGCArrayScanChunk) {
4802 end = start + ParGCArrayScanChunk;
4803 to_obj_array->set_length(end);
4804 // Push the remainder before we process the range in case another
4805 // worker has run out of things to do and can steal it.
4806 oop* from_obj_p = set_partial_array_mask(from_obj);
4807 _par_scan_state->push_on_queue(from_obj_p);
4808 } else {
4809 assert(length == end, "sanity");
4810 // We'll process the final range for this object. Restore the length
4811 // so that the heap remains parsable in case of evacuation failure.
4812 to_obj_array->set_length(end);
4813 }
4814 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4815 // Process indexes [start,end). It will also process the header
4816 // along with the first chunk (i.e., the chunk with start == 0).
4817 // Note that at this point the length field of to_obj_array is not
4818 // correct given that we are using it to keep track of the next
4819 // start index. oop_iterate_range() (thankfully!) ignores the length
4820 // field and only relies on the start / end parameters. It does
4821 // however return the size of the object which will be incorrect. So
4822 // we have to ignore it even if we wanted to use it.
4823 to_obj_array->oop_iterate_range(&_scanner, start, end);
4824 }
4825
4826 class G1ParEvacuateFollowersClosure : public VoidClosure {
4827 protected:
4828 G1CollectedHeap* _g1h;
4829 G1ParScanThreadState* _par_scan_state;
4830 RefToScanQueueSet* _queues;
4831 ParallelTaskTerminator* _terminator;
4832
4833 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4834 RefToScanQueueSet* queues() { return _queues; }
4835 ParallelTaskTerminator* terminator() { return _terminator; }
4836
4837 public:
4838 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4839 G1ParScanThreadState* par_scan_state,
4840 RefToScanQueueSet* queues,
4841 ParallelTaskTerminator* terminator)
4842 : _g1h(g1h), _par_scan_state(par_scan_state),
4843 _queues(queues), _terminator(terminator) {}
4844
4845 void do_void();
4846
4847 private:
4848 inline bool offer_termination();
4849 };
4850
4851 bool G1ParEvacuateFollowersClosure::offer_termination() {
4852 G1ParScanThreadState* const pss = par_scan_state();
4853 pss->start_term_time();
4854 const bool res = terminator()->offer_termination();
4855 pss->end_term_time();
4856 return res;
4857 }
4858
4859 void G1ParEvacuateFollowersClosure::do_void() {
4860 StarTask stolen_task;
4861 G1ParScanThreadState* const pss = par_scan_state();
4862 pss->trim_queue();
4863
4864 do {
4865 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4866 assert(pss->verify_task(stolen_task), "sanity");
4867 if (stolen_task.is_narrow()) {
4868 pss->deal_with_reference((narrowOop*) stolen_task);
4869 } else {
4870 pss->deal_with_reference((oop*) stolen_task);
4871 }
4872
4873 // We've just processed a reference and we might have made
4874 // available new entries on the queues. So we have to make sure
4875 // we drain the queues as necessary.
4876 pss->trim_queue();
4877 }
4878 } while (!offer_termination());
4879
4880 pss->retire_alloc_buffers();
4881 }
4882
4883 class G1KlassScanClosure : public KlassClosure {
4884 G1ParCopyHelper* _closure;
4885 bool _process_only_dirty;
4886 int _count;
4887 public:
4888 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4889 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4890 void do_klass(Klass* klass) {
4891 // If the klass has not been dirtied we know that there's
4892 // no references into the young gen and we can skip it.
4893 if (!_process_only_dirty || klass->has_modified_oops()) {
4894 // Clean the klass since we're going to scavenge all the metadata.
4895 klass->clear_modified_oops();
4896
4897 // Tell the closure that this klass is the Klass to scavenge
4898 // and is the one to dirty if oops are left pointing into the young gen.
4899 _closure->set_scanned_klass(klass);
4900
4901 klass->oops_do(_closure);
4902
4903 _closure->set_scanned_klass(NULL);
4904 }
4905 _count++;
4906 }
4907 };
4908
4909 class G1ParTask : public AbstractGangTask {
4910 protected:
4911 G1CollectedHeap* _g1h;
4912 RefToScanQueueSet *_queues;
4913 ParallelTaskTerminator _terminator;
4914 uint _n_workers;
4915
4916 Mutex _stats_lock;
4917 Mutex* stats_lock() { return &_stats_lock; }
4918
4919 size_t getNCards() {
4920 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4921 / G1BlockOffsetSharedArray::N_bytes;
4922 }
4923
4924 public:
4925 G1ParTask(G1CollectedHeap* g1h,
4926 RefToScanQueueSet *task_queues)
4927 : AbstractGangTask("G1 collection"),
4928 _g1h(g1h),
4929 _queues(task_queues),
4930 _terminator(0, _queues),
4931 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4932 {}
4933
4934 RefToScanQueueSet* queues() { return _queues; }
4935
4936 RefToScanQueue *work_queue(int i) {
4937 return queues()->queue(i);
4938 }
4939
4940 ParallelTaskTerminator* terminator() { return &_terminator; }
4941
4942 virtual void set_for_termination(int active_workers) {
4943 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4944 // in the young space (_par_seq_tasks) in the G1 heap
4945 // for SequentialSubTasksDone.
4946 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4947 // both of which need setting by set_n_termination().
4948 _g1h->SharedHeap::set_n_termination(active_workers);
4949 _g1h->set_n_termination(active_workers);
4950 terminator()->reset_for_reuse(active_workers);
4951 _n_workers = active_workers;
4952 }
4953
4954 void work(uint worker_id) {
4955 if (worker_id >= _n_workers) return; // no work needed this round
4956
4957 double start_time_ms = os::elapsedTime() * 1000.0;
4958 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4959
4960 {
4961 ResourceMark rm;
4962 HandleMark hm;
4963
4964 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4965
4966 G1ParScanThreadState pss(_g1h, worker_id);
4967 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4968 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4969 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4970
4971 pss.set_evac_closure(&scan_evac_cl);
4972 pss.set_evac_failure_closure(&evac_failure_cl);
4973 pss.set_partial_scan_closure(&partial_scan_cl);
4974
4975 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4976 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
4977
4978 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4979 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4980
4981 bool only_young = _g1h->g1_policy()->gcs_are_young();
4982 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4983 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4984
4985 OopClosure* scan_root_cl = &only_scan_root_cl;
4986 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
4987
4988 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4989 // We also need to mark copied objects.
4990 scan_root_cl = &scan_mark_root_cl;
4991 scan_klasses_cl = &scan_mark_klasses_cl_s;
4992 }
4993
4994 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4995
4996 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
4997
4998 pss.start_strong_roots();
4999 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5000 SharedHeap::ScanningOption(so),
5001 scan_root_cl,
5002 &push_heap_rs_cl,
5003 scan_klasses_cl,
5004 worker_id);
5005 pss.end_strong_roots();
5006
5007 {
5008 double start = os::elapsedTime();
5009 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5010 evac.do_void();
5011 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5012 double term_ms = pss.term_time()*1000.0;
5013 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5014 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5015 }
5016 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5017 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5018
5019 if (ParallelGCVerbose) {
5020 MutexLocker x(stats_lock());
5021 pss.print_termination_stats(worker_id);
5022 }
5023
5024 assert(pss.refs()->is_empty(), "should be empty");
5025
5026 // Close the inner scope so that the ResourceMark and HandleMark
5027 // destructors are executed here and are included as part of the
5028 // "GC Worker Time".
5029 }
5030
5031 double end_time_ms = os::elapsedTime() * 1000.0;
5032 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5033 }
5034 };
5035
5036 // *** Common G1 Evacuation Stuff
5037
5038 // Closures that support the filtering of CodeBlobs scanned during
5039 // external root scanning.
5040
5041 // Closure applied to reference fields in code blobs (specifically nmethods)
5042 // to determine whether an nmethod contains references that point into
5043 // the collection set. Used as a predicate when walking code roots so
5044 // that only nmethods that point into the collection set are added to the
5045 // 'marked' list.
5046
5047 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
5048
5049 class G1PointsIntoCSOopClosure : public OopClosure {
5050 G1CollectedHeap* _g1;
5051 bool _points_into_cs;
5052 public:
5053 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
5054 _g1(g1), _points_into_cs(false) { }
5055
5056 bool points_into_cs() const { return _points_into_cs; }
5057
5058 template <class T>
5059 void do_oop_nv(T* p) {
5060 if (!_points_into_cs) {
5061 T heap_oop = oopDesc::load_heap_oop(p);
5062 if (!oopDesc::is_null(heap_oop) &&
5063 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
5064 _points_into_cs = true;
5065 }
5066 }
5067 }
5068
5069 virtual void do_oop(oop* p) { do_oop_nv(p); }
5070 virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
5071 };
5072
5073 G1CollectedHeap* _g1;
5074
5075 public:
5076 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
5077 CodeBlobToOopClosure(cl, true), _g1(g1) { }
5078
5079 virtual void do_code_blob(CodeBlob* cb) {
5080 nmethod* nm = cb->as_nmethod_or_null();
5081 if (nm != NULL && !(nm->test_oops_do_mark())) {
5082 G1PointsIntoCSOopClosure predicate_cl(_g1);
5083 nm->oops_do(&predicate_cl);
5084
5085 if (predicate_cl.points_into_cs()) {
5086 // At least one of the reference fields or the oop relocations
5087 // in the nmethod points into the collection set. We have to
5088 // 'mark' this nmethod.
5089 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
5090 // or MarkingCodeBlobClosure::do_code_blob() change.
5091 if (!nm->test_set_oops_do_mark()) {
5092 do_newly_marked_nmethod(nm);
5093 }
5094 }
5095 }
5096 }
5097 };
5098
5099 // This method is run in a GC worker.
5100
5101 void
5102 G1CollectedHeap::
5103 g1_process_strong_roots(bool is_scavenging,
5104 ScanningOption so,
5105 OopClosure* scan_non_heap_roots,
5106 OopsInHeapRegionClosure* scan_rs,
5107 G1KlassScanClosure* scan_klasses,
5108 int worker_i) {
5109
5110 // First scan the strong roots
5111 double ext_roots_start = os::elapsedTime();
5112 double closure_app_time_sec = 0.0;
5113
5114 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5115
5116 // Walk the code cache w/o buffering, because StarTask cannot handle
5117 // unaligned oop locations.
5118 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
5119
5120 process_strong_roots(false, // no scoping; this is parallel code
5121 is_scavenging, so,
5122 &buf_scan_non_heap_roots,
5123 &eager_scan_code_roots,
5124 scan_klasses
5125 );
5126
5127 // Now the CM ref_processor roots.
5128 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5129 // We need to treat the discovered reference lists of the
5130 // concurrent mark ref processor as roots and keep entries
5131 // (which are added by the marking threads) on them live
5132 // until they can be processed at the end of marking.
5133 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5134 }
5135
5136 // Finish up any enqueued closure apps (attributed as object copy time).
5137 buf_scan_non_heap_roots.done();
5138
5139 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5140
5141 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5142
5143 double ext_root_time_ms =
5144 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5145
5146 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5147
5148 // During conc marking we have to filter the per-thread SATB buffers
5149 // to make sure we remove any oops into the CSet (which will show up
5150 // as implicitly live).
5151 double satb_filtering_ms = 0.0;
5152 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5153 if (mark_in_progress()) {
5154 double satb_filter_start = os::elapsedTime();
5155
5156 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5157
5158 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5159 }
5160 }
5161 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5162
5163 // Now scan the complement of the collection set.
5164 if (scan_rs != NULL) {
5165 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
5166 }
5167 _process_strong_tasks->all_tasks_completed();
5168 }
5169
5170 void
5171 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5172 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5173 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5174 }
5175
5176 // Weak Reference Processing support
5177
5178 // An always "is_alive" closure that is used to preserve referents.
5179 // If the object is non-null then it's alive. Used in the preservation
5180 // of referent objects that are pointed to by reference objects
5181 // discovered by the CM ref processor.
5182 class G1AlwaysAliveClosure: public BoolObjectClosure {
5183 G1CollectedHeap* _g1;
5184 public:
5185 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5186 bool do_object_b(oop p) {
5187 if (p != NULL) {
5188 return true;
5189 }
5190 return false;
5191 }
5192 };
5193
5194 bool G1STWIsAliveClosure::do_object_b(oop p) {
5195 // An object is reachable if it is outside the collection set,
5196 // or is inside and copied.
5197 return !_g1->obj_in_cs(p) || p->is_forwarded();
5198 }
5199
5200 // Non Copying Keep Alive closure
5201 class G1KeepAliveClosure: public OopClosure {
5202 G1CollectedHeap* _g1;
5203 public:
5204 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5205 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5206 void do_oop( oop* p) {
5207 oop obj = *p;
5208
5209 if (_g1->obj_in_cs(obj)) {
5210 assert( obj->is_forwarded(), "invariant" );
5211 *p = obj->forwardee();
5212 }
5213 }
5214 };
5215
5216 // Copying Keep Alive closure - can be called from both
5217 // serial and parallel code as long as different worker
5218 // threads utilize different G1ParScanThreadState instances
5219 // and different queues.
5220
5221 class G1CopyingKeepAliveClosure: public OopClosure {
5222 G1CollectedHeap* _g1h;
5223 OopClosure* _copy_non_heap_obj_cl;
5224 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5225 G1ParScanThreadState* _par_scan_state;
5226
5227 public:
5228 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5229 OopClosure* non_heap_obj_cl,
5230 OopsInHeapRegionClosure* metadata_obj_cl,
5231 G1ParScanThreadState* pss):
5232 _g1h(g1h),
5233 _copy_non_heap_obj_cl(non_heap_obj_cl),
5234 _copy_metadata_obj_cl(metadata_obj_cl),
5235 _par_scan_state(pss)
5236 {}
5237
5238 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5239 virtual void do_oop( oop* p) { do_oop_work(p); }
5240
5241 template <class T> void do_oop_work(T* p) {
5242 oop obj = oopDesc::load_decode_heap_oop(p);
5243
5244 if (_g1h->obj_in_cs(obj)) {
5245 // If the referent object has been forwarded (either copied
5246 // to a new location or to itself in the event of an
5247 // evacuation failure) then we need to update the reference
5248 // field and, if both reference and referent are in the G1
5249 // heap, update the RSet for the referent.
5250 //
5251 // If the referent has not been forwarded then we have to keep
5252 // it alive by policy. Therefore we have copy the referent.
5253 //
5254 // If the reference field is in the G1 heap then we can push
5255 // on the PSS queue. When the queue is drained (after each
5256 // phase of reference processing) the object and it's followers
5257 // will be copied, the reference field set to point to the
5258 // new location, and the RSet updated. Otherwise we need to
5259 // use the the non-heap or metadata closures directly to copy
5260 // the referent object and update the pointer, while avoiding
5261 // updating the RSet.
5262
5263 if (_g1h->is_in_g1_reserved(p)) {
5264 _par_scan_state->push_on_queue(p);
5265 } else {
5266 assert(!ClassLoaderDataGraph::contains((address)p),
5267 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5268 PTR_FORMAT, p));
5269 _copy_non_heap_obj_cl->do_oop(p);
5270 }
5271 }
5272 }
5273 };
5274
5275 // Serial drain queue closure. Called as the 'complete_gc'
5276 // closure for each discovered list in some of the
5277 // reference processing phases.
5278
5279 class G1STWDrainQueueClosure: public VoidClosure {
5280 protected:
5281 G1CollectedHeap* _g1h;
5282 G1ParScanThreadState* _par_scan_state;
5283
5284 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5285
5286 public:
5287 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5288 _g1h(g1h),
5289 _par_scan_state(pss)
5290 { }
5291
5292 void do_void() {
5293 G1ParScanThreadState* const pss = par_scan_state();
5294 pss->trim_queue();
5295 }
5296 };
5297
5298 // Parallel Reference Processing closures
5299
5300 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5301 // processing during G1 evacuation pauses.
5302
5303 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5304 private:
5305 G1CollectedHeap* _g1h;
5306 RefToScanQueueSet* _queues;
5307 FlexibleWorkGang* _workers;
5308 int _active_workers;
5309
5310 public:
5311 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5312 FlexibleWorkGang* workers,
5313 RefToScanQueueSet *task_queues,
5314 int n_workers) :
5315 _g1h(g1h),
5316 _queues(task_queues),
5317 _workers(workers),
5318 _active_workers(n_workers)
5319 {
5320 assert(n_workers > 0, "shouldn't call this otherwise");
5321 }
5322
5323 // Executes the given task using concurrent marking worker threads.
5324 virtual void execute(ProcessTask& task);
5325 virtual void execute(EnqueueTask& task);
5326 };
5327
5328 // Gang task for possibly parallel reference processing
5329
5330 class G1STWRefProcTaskProxy: public AbstractGangTask {
5331 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5332 ProcessTask& _proc_task;
5333 G1CollectedHeap* _g1h;
5334 RefToScanQueueSet *_task_queues;
5335 ParallelTaskTerminator* _terminator;
5336
5337 public:
5338 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5339 G1CollectedHeap* g1h,
5340 RefToScanQueueSet *task_queues,
5341 ParallelTaskTerminator* terminator) :
5342 AbstractGangTask("Process reference objects in parallel"),
5343 _proc_task(proc_task),
5344 _g1h(g1h),
5345 _task_queues(task_queues),
5346 _terminator(terminator)
5347 {}
5348
5349 virtual void work(uint worker_id) {
5350 // The reference processing task executed by a single worker.
5351 ResourceMark rm;
5352 HandleMark hm;
5353
5354 G1STWIsAliveClosure is_alive(_g1h);
5355
5356 G1ParScanThreadState pss(_g1h, worker_id);
5357
5358 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5359 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5360 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5361
5362 pss.set_evac_closure(&scan_evac_cl);
5363 pss.set_evac_failure_closure(&evac_failure_cl);
5364 pss.set_partial_scan_closure(&partial_scan_cl);
5365
5366 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5367 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5368
5369 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5370 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5371
5372 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5373 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5374
5375 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5376 // We also need to mark copied objects.
5377 copy_non_heap_cl = ©_mark_non_heap_cl;
5378 copy_metadata_cl = ©_mark_metadata_cl;
5379 }
5380
5381 // Keep alive closure.
5382 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5383
5384 // Complete GC closure
5385 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5386
5387 // Call the reference processing task's work routine.
5388 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5389
5390 // Note we cannot assert that the refs array is empty here as not all
5391 // of the processing tasks (specifically phase2 - pp2_work) execute
5392 // the complete_gc closure (which ordinarily would drain the queue) so
5393 // the queue may not be empty.
5394 }
5395 };
5396
5397 // Driver routine for parallel reference processing.
5398 // Creates an instance of the ref processing gang
5399 // task and has the worker threads execute it.
5400 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5401 assert(_workers != NULL, "Need parallel worker threads.");
5402
5403 ParallelTaskTerminator terminator(_active_workers, _queues);
5404 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5405
5406 _g1h->set_par_threads(_active_workers);
5407 _workers->run_task(&proc_task_proxy);
5408 _g1h->set_par_threads(0);
5409 }
5410
5411 // Gang task for parallel reference enqueueing.
5412
5413 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5414 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5415 EnqueueTask& _enq_task;
5416
5417 public:
5418 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5419 AbstractGangTask("Enqueue reference objects in parallel"),
5420 _enq_task(enq_task)
5421 { }
5422
5423 virtual void work(uint worker_id) {
5424 _enq_task.work(worker_id);
5425 }
5426 };
5427
5428 // Driver routine for parallel reference enqueueing.
5429 // Creates an instance of the ref enqueueing gang
5430 // task and has the worker threads execute it.
5431
5432 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5433 assert(_workers != NULL, "Need parallel worker threads.");
5434
5435 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5436
5437 _g1h->set_par_threads(_active_workers);
5438 _workers->run_task(&enq_task_proxy);
5439 _g1h->set_par_threads(0);
5440 }
5441
5442 // End of weak reference support closures
5443
5444 // Abstract task used to preserve (i.e. copy) any referent objects
5445 // that are in the collection set and are pointed to by reference
5446 // objects discovered by the CM ref processor.
5447
5448 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5449 protected:
5450 G1CollectedHeap* _g1h;
5451 RefToScanQueueSet *_queues;
5452 ParallelTaskTerminator _terminator;
5453 uint _n_workers;
5454
5455 public:
5456 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5457 AbstractGangTask("ParPreserveCMReferents"),
5458 _g1h(g1h),
5459 _queues(task_queues),
5460 _terminator(workers, _queues),
5461 _n_workers(workers)
5462 { }
5463
5464 void work(uint worker_id) {
5465 ResourceMark rm;
5466 HandleMark hm;
5467
5468 G1ParScanThreadState pss(_g1h, worker_id);
5469 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5470 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5471 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5472
5473 pss.set_evac_closure(&scan_evac_cl);
5474 pss.set_evac_failure_closure(&evac_failure_cl);
5475 pss.set_partial_scan_closure(&partial_scan_cl);
5476
5477 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5478
5479
5480 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5481 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5482
5483 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5484 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5485
5486 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5487 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5488
5489 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5490 // We also need to mark copied objects.
5491 copy_non_heap_cl = ©_mark_non_heap_cl;
5492 copy_metadata_cl = ©_mark_metadata_cl;
5493 }
5494
5495 // Is alive closure
5496 G1AlwaysAliveClosure always_alive(_g1h);
5497
5498 // Copying keep alive closure. Applied to referent objects that need
5499 // to be copied.
5500 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5501
5502 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5503
5504 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5505 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5506
5507 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5508 // So this must be true - but assert just in case someone decides to
5509 // change the worker ids.
5510 assert(0 <= worker_id && worker_id < limit, "sanity");
5511 assert(!rp->discovery_is_atomic(), "check this code");
5512
5513 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5514 for (uint idx = worker_id; idx < limit; idx += stride) {
5515 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5516
5517 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5518 while (iter.has_next()) {
5519 // Since discovery is not atomic for the CM ref processor, we
5520 // can see some null referent objects.
5521 iter.load_ptrs(DEBUG_ONLY(true));
5522 oop ref = iter.obj();
5523
5524 // This will filter nulls.
5525 if (iter.is_referent_alive()) {
5526 iter.make_referent_alive();
5527 }
5528 iter.move_to_next();
5529 }
5530 }
5531
5532 // Drain the queue - which may cause stealing
5533 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5534 drain_queue.do_void();
5535 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5536 assert(pss.refs()->is_empty(), "should be");
5537 }
5538 };
5539
5540 // Weak Reference processing during an evacuation pause (part 1).
5541 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5542 double ref_proc_start = os::elapsedTime();
5543
5544 ReferenceProcessor* rp = _ref_processor_stw;
5545 assert(rp->discovery_enabled(), "should have been enabled");
5546
5547 // Any reference objects, in the collection set, that were 'discovered'
5548 // by the CM ref processor should have already been copied (either by
5549 // applying the external root copy closure to the discovered lists, or
5550 // by following an RSet entry).
5551 //
5552 // But some of the referents, that are in the collection set, that these
5553 // reference objects point to may not have been copied: the STW ref
5554 // processor would have seen that the reference object had already
5555 // been 'discovered' and would have skipped discovering the reference,
5556 // but would not have treated the reference object as a regular oop.
5557 // As a result the copy closure would not have been applied to the
5558 // referent object.
5559 //
5560 // We need to explicitly copy these referent objects - the references
5561 // will be processed at the end of remarking.
5562 //
5563 // We also need to do this copying before we process the reference
5564 // objects discovered by the STW ref processor in case one of these
5565 // referents points to another object which is also referenced by an
5566 // object discovered by the STW ref processor.
5567
5568 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5569 no_of_gc_workers == workers()->active_workers(),
5570 "Need to reset active GC workers");
5571
5572 set_par_threads(no_of_gc_workers);
5573 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5574 no_of_gc_workers,
5575 _task_queues);
5576
5577 if (G1CollectedHeap::use_parallel_gc_threads()) {
5578 workers()->run_task(&keep_cm_referents);
5579 } else {
5580 keep_cm_referents.work(0);
5581 }
5582
5583 set_par_threads(0);
5584
5585 // Closure to test whether a referent is alive.
5586 G1STWIsAliveClosure is_alive(this);
5587
5588 // Even when parallel reference processing is enabled, the processing
5589 // of JNI refs is serial and performed serially by the current thread
5590 // rather than by a worker. The following PSS will be used for processing
5591 // JNI refs.
5592
5593 // Use only a single queue for this PSS.
5594 G1ParScanThreadState pss(this, 0);
5595
5596 // We do not embed a reference processor in the copying/scanning
5597 // closures while we're actually processing the discovered
5598 // reference objects.
5599 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5600 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5601 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5602
5603 pss.set_evac_closure(&scan_evac_cl);
5604 pss.set_evac_failure_closure(&evac_failure_cl);
5605 pss.set_partial_scan_closure(&partial_scan_cl);
5606
5607 assert(pss.refs()->is_empty(), "pre-condition");
5608
5609 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5610 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5611
5612 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5613 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5614
5615 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5616 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5617
5618 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5619 // We also need to mark copied objects.
5620 copy_non_heap_cl = ©_mark_non_heap_cl;
5621 copy_metadata_cl = ©_mark_metadata_cl;
5622 }
5623
5624 // Keep alive closure.
5625 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5626
5627 // Serial Complete GC closure
5628 G1STWDrainQueueClosure drain_queue(this, &pss);
5629
5630 // Setup the soft refs policy...
5631 rp->setup_policy(false);
5632
5633 ReferenceProcessorStats stats;
5634 if (!rp->processing_is_mt()) {
5635 // Serial reference processing...
5636 stats = rp->process_discovered_references(&is_alive,
5637 &keep_alive,
5638 &drain_queue,
5639 NULL,
5640 _gc_timer_stw);
5641 } else {
5642 // Parallel reference processing
5643 assert(rp->num_q() == no_of_gc_workers, "sanity");
5644 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5645
5646 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5647 stats = rp->process_discovered_references(&is_alive,
5648 &keep_alive,
5649 &drain_queue,
5650 &par_task_executor,
5651 _gc_timer_stw);
5652 }
5653
5654 _gc_tracer_stw->report_gc_reference_stats(stats);
5655 // We have completed copying any necessary live referent objects
5656 // (that were not copied during the actual pause) so we can
5657 // retire any active alloc buffers
5658 pss.retire_alloc_buffers();
5659 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5660
5661 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5662 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5663 }
5664
5665 // Weak Reference processing during an evacuation pause (part 2).
5666 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5667 double ref_enq_start = os::elapsedTime();
5668
5669 ReferenceProcessor* rp = _ref_processor_stw;
5670 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5671
5672 // Now enqueue any remaining on the discovered lists on to
5673 // the pending list.
5674 if (!rp->processing_is_mt()) {
5675 // Serial reference processing...
5676 rp->enqueue_discovered_references();
5677 } else {
5678 // Parallel reference enqueueing
5679
5680 assert(no_of_gc_workers == workers()->active_workers(),
5681 "Need to reset active workers");
5682 assert(rp->num_q() == no_of_gc_workers, "sanity");
5683 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5684
5685 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5686 rp->enqueue_discovered_references(&par_task_executor);
5687 }
5688
5689 rp->verify_no_references_recorded();
5690 assert(!rp->discovery_enabled(), "should have been disabled");
5691
5692 // FIXME
5693 // CM's reference processing also cleans up the string and symbol tables.
5694 // Should we do that here also? We could, but it is a serial operation
5695 // and could significantly increase the pause time.
5696
5697 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5698 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5699 }
5700
5701 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5702 _expand_heap_after_alloc_failure = true;
5703 _evacuation_failed = false;
5704
5705 // Should G1EvacuationFailureALot be in effect for this GC?
5706 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5707
5708 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5709
5710 // Disable the hot card cache.
5711 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5712 hot_card_cache->reset_hot_cache_claimed_index();
5713 hot_card_cache->set_use_cache(false);
5714
5715 uint n_workers;
5716 if (G1CollectedHeap::use_parallel_gc_threads()) {
5717 n_workers =
5718 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5719 workers()->active_workers(),
5720 Threads::number_of_non_daemon_threads());
5721 assert(UseDynamicNumberOfGCThreads ||
5722 n_workers == workers()->total_workers(),
5723 "If not dynamic should be using all the workers");
5724 workers()->set_active_workers(n_workers);
5725 set_par_threads(n_workers);
5726 } else {
5727 assert(n_par_threads() == 0,
5728 "Should be the original non-parallel value");
5729 n_workers = 1;
5730 }
5731
5732 G1ParTask g1_par_task(this, _task_queues);
5733
5734 init_for_evac_failure(NULL);
5735
5736 rem_set()->prepare_for_younger_refs_iterate(true);
5737
5738 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5739 double start_par_time_sec = os::elapsedTime();
5740 double end_par_time_sec;
5741
5742 {
5743 StrongRootsScope srs(this);
5744
5745 if (G1CollectedHeap::use_parallel_gc_threads()) {
5746 // The individual threads will set their evac-failure closures.
5747 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5748 // These tasks use ShareHeap::_process_strong_tasks
5749 assert(UseDynamicNumberOfGCThreads ||
5750 workers()->active_workers() == workers()->total_workers(),
5751 "If not dynamic should be using all the workers");
5752 workers()->run_task(&g1_par_task);
5753 } else {
5754 g1_par_task.set_for_termination(n_workers);
5755 g1_par_task.work(0);
5756 }
5757 end_par_time_sec = os::elapsedTime();
5758
5759 // Closing the inner scope will execute the destructor
5760 // for the StrongRootsScope object. We record the current
5761 // elapsed time before closing the scope so that time
5762 // taken for the SRS destructor is NOT included in the
5763 // reported parallel time.
5764 }
5765
5766 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5767 g1_policy()->phase_times()->record_par_time(par_time_ms);
5768
5769 double code_root_fixup_time_ms =
5770 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5771 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5772
5773 set_par_threads(0);
5774
5775 // Process any discovered reference objects - we have
5776 // to do this _before_ we retire the GC alloc regions
5777 // as we may have to copy some 'reachable' referent
5778 // objects (and their reachable sub-graphs) that were
5779 // not copied during the pause.
5780 process_discovered_references(n_workers);
5781
5782 // Weak root processing.
5783 // Note: when JSR 292 is enabled and code blobs can contain
5784 // non-perm oops then we will need to process the code blobs
5785 // here too.
5786 {
5787 G1STWIsAliveClosure is_alive(this);
5788 G1KeepAliveClosure keep_alive(this);
5789 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5790 }
5791
5792 release_gc_alloc_regions(n_workers, evacuation_info);
5793 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5794
5795 // Reset and re-enable the hot card cache.
5796 // Note the counts for the cards in the regions in the
5797 // collection set are reset when the collection set is freed.
5798 hot_card_cache->reset_hot_cache();
5799 hot_card_cache->set_use_cache(true);
5800
5801 finalize_for_evac_failure();
5802
5803 if (evacuation_failed()) {
5804 remove_self_forwarding_pointers();
5805
5806 // Reset the G1EvacuationFailureALot counters and flags
5807 // Note: the values are reset only when an actual
5808 // evacuation failure occurs.
5809 NOT_PRODUCT(reset_evacuation_should_fail();)
5810 }
5811
5812 // Enqueue any remaining references remaining on the STW
5813 // reference processor's discovered lists. We need to do
5814 // this after the card table is cleaned (and verified) as
5815 // the act of enqueueing entries on to the pending list
5816 // will log these updates (and dirty their associated
5817 // cards). We need these updates logged to update any
5818 // RSets.
5819 enqueue_discovered_references(n_workers);
5820
5821 if (G1DeferredRSUpdate) {
5822 RedirtyLoggedCardTableEntryFastClosure redirty;
5823 dirty_card_queue_set().set_closure(&redirty);
5824 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5825
5826 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5827 dcq.merge_bufferlists(&dirty_card_queue_set());
5828 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5829 }
5830 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5831 }
5832
5833 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5834 size_t* pre_used,
5835 FreeRegionList* free_list,
5836 OldRegionSet* old_proxy_set,
5837 HumongousRegionSet* humongous_proxy_set,
5838 HRRSCleanupTask* hrrs_cleanup_task,
5839 bool par) {
5840 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5841 if (hr->isHumongous()) {
5842 assert(hr->startsHumongous(), "we should only see starts humongous");
5843 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5844 } else {
5845 _old_set.remove_with_proxy(hr, old_proxy_set);
5846 free_region(hr, pre_used, free_list, par);
5847 }
5848 } else {
5849 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5850 }
5851 }
5852
5853 void G1CollectedHeap::free_region(HeapRegion* hr,
5854 size_t* pre_used,
5855 FreeRegionList* free_list,
5856 bool par) {
5857 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5858 assert(!hr->is_empty(), "the region should not be empty");
5859 assert(free_list != NULL, "pre-condition");
5860
5861 // Clear the card counts for this region.
5862 // Note: we only need to do this if the region is not young
5863 // (since we don't refine cards in young regions).
5864 if (!hr->is_young()) {
5865 _cg1r->hot_card_cache()->reset_card_counts(hr);
5866 }
5867 *pre_used += hr->used();
5868 hr->hr_clear(par, true /* clear_space */);
5869 free_list->add_as_head(hr);
5870 }
5871
5872 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5873 size_t* pre_used,
5874 FreeRegionList* free_list,
5875 HumongousRegionSet* humongous_proxy_set,
5876 bool par) {
5877 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5878 assert(free_list != NULL, "pre-condition");
5879 assert(humongous_proxy_set != NULL, "pre-condition");
5880
5881 size_t hr_used = hr->used();
5882 size_t hr_capacity = hr->capacity();
5883 size_t hr_pre_used = 0;
5884 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5885 // We need to read this before we make the region non-humongous,
5886 // otherwise the information will be gone.
5887 uint last_index = hr->last_hc_index();
5888 hr->set_notHumongous();
5889 free_region(hr, &hr_pre_used, free_list, par);
5890
5891 uint i = hr->hrs_index() + 1;
5892 while (i < last_index) {
5893 HeapRegion* curr_hr = region_at(i);
5894 assert(curr_hr->continuesHumongous(), "invariant");
5895 curr_hr->set_notHumongous();
5896 free_region(curr_hr, &hr_pre_used, free_list, par);
5897 i += 1;
5898 }
5899 assert(hr_pre_used == hr_used,
5900 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5901 "should be the same", hr_pre_used, hr_used));
5902 *pre_used += hr_pre_used;
5903 }
5904
5905 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5906 FreeRegionList* free_list,
5907 OldRegionSet* old_proxy_set,
5908 HumongousRegionSet* humongous_proxy_set,
5909 bool par) {
5910 if (pre_used > 0) {
5911 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5912 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5913 assert(_summary_bytes_used >= pre_used,
5914 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5915 "should be >= pre_used: "SIZE_FORMAT,
5916 _summary_bytes_used, pre_used));
5917 _summary_bytes_used -= pre_used;
5918 }
5919 if (free_list != NULL && !free_list->is_empty()) {
5920 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5921 _free_list.add_as_head(free_list);
5922 }
5923 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5924 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5925 _old_set.update_from_proxy(old_proxy_set);
5926 }
5927 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5928 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5929 _humongous_set.update_from_proxy(humongous_proxy_set);
5930 }
5931 }
5932
5933 class G1ParCleanupCTTask : public AbstractGangTask {
5934 CardTableModRefBS* _ct_bs;
5935 G1CollectedHeap* _g1h;
5936 HeapRegion* volatile _su_head;
5937 public:
5938 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5939 G1CollectedHeap* g1h) :
5940 AbstractGangTask("G1 Par Cleanup CT Task"),
5941 _ct_bs(ct_bs), _g1h(g1h) { }
5942
5943 void work(uint worker_id) {
5944 HeapRegion* r;
5945 while (r = _g1h->pop_dirty_cards_region()) {
5946 clear_cards(r);
5947 }
5948 }
5949
5950 void clear_cards(HeapRegion* r) {
5951 // Cards of the survivors should have already been dirtied.
5952 if (!r->is_survivor()) {
5953 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5954 }
5955 }
5956 };
5957
5958 #ifndef PRODUCT
5959 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5960 G1CollectedHeap* _g1h;
5961 CardTableModRefBS* _ct_bs;
5962 public:
5963 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5964 : _g1h(g1h), _ct_bs(ct_bs) { }
5965 virtual bool doHeapRegion(HeapRegion* r) {
5966 if (r->is_survivor()) {
5967 _g1h->verify_dirty_region(r);
5968 } else {
5969 _g1h->verify_not_dirty_region(r);
5970 }
5971 return false;
5972 }
5973 };
5974
5975 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5976 // All of the region should be clean.
5977 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5978 MemRegion mr(hr->bottom(), hr->end());
5979 ct_bs->verify_not_dirty_region(mr);
5980 }
5981
5982 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5983 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5984 // dirty allocated blocks as they allocate them. The thread that
5985 // retires each region and replaces it with a new one will do a
5986 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5987 // not dirty that area (one less thing to have to do while holding
5988 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5989 // is dirty.
5990 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5991 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5992 ct_bs->verify_dirty_region(mr);
5993 }
5994
5995 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5996 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5997 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5998 verify_dirty_region(hr);
5999 }
6000 }
6001
6002 void G1CollectedHeap::verify_dirty_young_regions() {
6003 verify_dirty_young_list(_young_list->first_region());
6004 }
6005 #endif
6006
6007 void G1CollectedHeap::cleanUpCardTable() {
6008 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
6009 double start = os::elapsedTime();
6010
6011 {
6012 // Iterate over the dirty cards region list.
6013 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6014
6015 if (G1CollectedHeap::use_parallel_gc_threads()) {
6016 set_par_threads();
6017 workers()->run_task(&cleanup_task);
6018 set_par_threads(0);
6019 } else {
6020 while (_dirty_cards_region_list) {
6021 HeapRegion* r = _dirty_cards_region_list;
6022 cleanup_task.clear_cards(r);
6023 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6024 if (_dirty_cards_region_list == r) {
6025 // The last region.
6026 _dirty_cards_region_list = NULL;
6027 }
6028 r->set_next_dirty_cards_region(NULL);
6029 }
6030 }
6031 #ifndef PRODUCT
6032 if (G1VerifyCTCleanup || VerifyAfterGC) {
6033 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6034 heap_region_iterate(&cleanup_verifier);
6035 }
6036 #endif
6037 }
6038
6039 double elapsed = os::elapsedTime() - start;
6040 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6041 }
6042
6043 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6044 size_t pre_used = 0;
6045 FreeRegionList local_free_list("Local List for CSet Freeing");
6046
6047 double young_time_ms = 0.0;
6048 double non_young_time_ms = 0.0;
6049
6050 // Since the collection set is a superset of the the young list,
6051 // all we need to do to clear the young list is clear its
6052 // head and length, and unlink any young regions in the code below
6053 _young_list->clear();
6054
6055 G1CollectorPolicy* policy = g1_policy();
6056
6057 double start_sec = os::elapsedTime();
6058 bool non_young = true;
6059
6060 HeapRegion* cur = cs_head;
6061 int age_bound = -1;
6062 size_t rs_lengths = 0;
6063
6064 while (cur != NULL) {
6065 assert(!is_on_master_free_list(cur), "sanity");
6066 if (non_young) {
6067 if (cur->is_young()) {
6068 double end_sec = os::elapsedTime();
6069 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6070 non_young_time_ms += elapsed_ms;
6071
6072 start_sec = os::elapsedTime();
6073 non_young = false;
6074 }
6075 } else {
6076 if (!cur->is_young()) {
6077 double end_sec = os::elapsedTime();
6078 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6079 young_time_ms += elapsed_ms;
6080
6081 start_sec = os::elapsedTime();
6082 non_young = true;
6083 }
6084 }
6085
6086 rs_lengths += cur->rem_set()->occupied();
6087
6088 HeapRegion* next = cur->next_in_collection_set();
6089 assert(cur->in_collection_set(), "bad CS");
6090 cur->set_next_in_collection_set(NULL);
6091 cur->set_in_collection_set(false);
6092
6093 if (cur->is_young()) {
6094 int index = cur->young_index_in_cset();
6095 assert(index != -1, "invariant");
6096 assert((uint) index < policy->young_cset_region_length(), "invariant");
6097 size_t words_survived = _surviving_young_words[index];
6098 cur->record_surv_words_in_group(words_survived);
6099
6100 // At this point the we have 'popped' cur from the collection set
6101 // (linked via next_in_collection_set()) but it is still in the
6102 // young list (linked via next_young_region()). Clear the
6103 // _next_young_region field.
6104 cur->set_next_young_region(NULL);
6105 } else {
6106 int index = cur->young_index_in_cset();
6107 assert(index == -1, "invariant");
6108 }
6109
6110 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6111 (!cur->is_young() && cur->young_index_in_cset() == -1),
6112 "invariant" );
6113
6114 if (!cur->evacuation_failed()) {
6115 MemRegion used_mr = cur->used_region();
6116
6117 // And the region is empty.
6118 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6119 free_region(cur, &pre_used, &local_free_list, false /* par */);
6120 } else {
6121 cur->uninstall_surv_rate_group();
6122 if (cur->is_young()) {
6123 cur->set_young_index_in_cset(-1);
6124 }
6125 cur->set_not_young();
6126 cur->set_evacuation_failed(false);
6127 // The region is now considered to be old.
6128 _old_set.add(cur);
6129 evacuation_info.increment_collectionset_used_after(cur->used());
6130 }
6131 cur = next;
6132 }
6133
6134 evacuation_info.set_regions_freed(local_free_list.length());
6135 policy->record_max_rs_lengths(rs_lengths);
6136 policy->cset_regions_freed();
6137
6138 double end_sec = os::elapsedTime();
6139 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6140
6141 if (non_young) {
6142 non_young_time_ms += elapsed_ms;
6143 } else {
6144 young_time_ms += elapsed_ms;
6145 }
6146
6147 update_sets_after_freeing_regions(pre_used, &local_free_list,
6148 NULL /* old_proxy_set */,
6149 NULL /* humongous_proxy_set */,
6150 false /* par */);
6151 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6152 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6153 }
6154
6155 // This routine is similar to the above but does not record
6156 // any policy statistics or update free lists; we are abandoning
6157 // the current incremental collection set in preparation of a
6158 // full collection. After the full GC we will start to build up
6159 // the incremental collection set again.
6160 // This is only called when we're doing a full collection
6161 // and is immediately followed by the tearing down of the young list.
6162
6163 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6164 HeapRegion* cur = cs_head;
6165
6166 while (cur != NULL) {
6167 HeapRegion* next = cur->next_in_collection_set();
6168 assert(cur->in_collection_set(), "bad CS");
6169 cur->set_next_in_collection_set(NULL);
6170 cur->set_in_collection_set(false);
6171 cur->set_young_index_in_cset(-1);
6172 cur = next;
6173 }
6174 }
6175
6176 void G1CollectedHeap::set_free_regions_coming() {
6177 if (G1ConcRegionFreeingVerbose) {
6178 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6179 "setting free regions coming");
6180 }
6181
6182 assert(!free_regions_coming(), "pre-condition");
6183 _free_regions_coming = true;
6184 }
6185
6186 void G1CollectedHeap::reset_free_regions_coming() {
6187 assert(free_regions_coming(), "pre-condition");
6188
6189 {
6190 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6191 _free_regions_coming = false;
6192 SecondaryFreeList_lock->notify_all();
6193 }
6194
6195 if (G1ConcRegionFreeingVerbose) {
6196 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6197 "reset free regions coming");
6198 }
6199 }
6200
6201 void G1CollectedHeap::wait_while_free_regions_coming() {
6202 // Most of the time we won't have to wait, so let's do a quick test
6203 // first before we take the lock.
6204 if (!free_regions_coming()) {
6205 return;
6206 }
6207
6208 if (G1ConcRegionFreeingVerbose) {
6209 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6210 "waiting for free regions");
6211 }
6212
6213 {
6214 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6215 while (free_regions_coming()) {
6216 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6217 }
6218 }
6219
6220 if (G1ConcRegionFreeingVerbose) {
6221 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6222 "done waiting for free regions");
6223 }
6224 }
6225
6226 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6227 assert(heap_lock_held_for_gc(),
6228 "the heap lock should already be held by or for this thread");
6229 _young_list->push_region(hr);
6230 }
6231
6232 class NoYoungRegionsClosure: public HeapRegionClosure {
6233 private:
6234 bool _success;
6235 public:
6236 NoYoungRegionsClosure() : _success(true) { }
6237 bool doHeapRegion(HeapRegion* r) {
6238 if (r->is_young()) {
6239 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6240 r->bottom(), r->end());
6241 _success = false;
6242 }
6243 return false;
6244 }
6245 bool success() { return _success; }
6246 };
6247
6248 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6249 bool ret = _young_list->check_list_empty(check_sample);
6250
6251 if (check_heap) {
6252 NoYoungRegionsClosure closure;
6253 heap_region_iterate(&closure);
6254 ret = ret && closure.success();
6255 }
6256
6257 return ret;
6258 }
6259
6260 class TearDownRegionSetsClosure : public HeapRegionClosure {
6261 private:
6262 OldRegionSet *_old_set;
6263
6264 public:
6265 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6266
6267 bool doHeapRegion(HeapRegion* r) {
6268 if (r->is_empty()) {
6269 // We ignore empty regions, we'll empty the free list afterwards
6270 } else if (r->is_young()) {
6271 // We ignore young regions, we'll empty the young list afterwards
6272 } else if (r->isHumongous()) {
6273 // We ignore humongous regions, we're not tearing down the
6274 // humongous region set
6275 } else {
6276 // The rest should be old
6277 _old_set->remove(r);
6278 }
6279 return false;
6280 }
6281
6282 ~TearDownRegionSetsClosure() {
6283 assert(_old_set->is_empty(), "post-condition");
6284 }
6285 };
6286
6287 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6288 assert_at_safepoint(true /* should_be_vm_thread */);
6289
6290 if (!free_list_only) {
6291 TearDownRegionSetsClosure cl(&_old_set);
6292 heap_region_iterate(&cl);
6293
6294 // Need to do this after the heap iteration to be able to
6295 // recognize the young regions and ignore them during the iteration.
6296 _young_list->empty_list();
6297 }
6298 _free_list.remove_all();
6299 }
6300
6301 class RebuildRegionSetsClosure : public HeapRegionClosure {
6302 private:
6303 bool _free_list_only;
6304 OldRegionSet* _old_set;
6305 FreeRegionList* _free_list;
6306 size_t _total_used;
6307
6308 public:
6309 RebuildRegionSetsClosure(bool free_list_only,
6310 OldRegionSet* old_set, FreeRegionList* free_list) :
6311 _free_list_only(free_list_only),
6312 _old_set(old_set), _free_list(free_list), _total_used(0) {
6313 assert(_free_list->is_empty(), "pre-condition");
6314 if (!free_list_only) {
6315 assert(_old_set->is_empty(), "pre-condition");
6316 }
6317 }
6318
6319 bool doHeapRegion(HeapRegion* r) {
6320 if (r->continuesHumongous()) {
6321 return false;
6322 }
6323
6324 if (r->is_empty()) {
6325 // Add free regions to the free list
6326 _free_list->add_as_tail(r);
6327 } else if (!_free_list_only) {
6328 assert(!r->is_young(), "we should not come across young regions");
6329
6330 if (r->isHumongous()) {
6331 // We ignore humongous regions, we left the humongous set unchanged
6332 } else {
6333 // The rest should be old, add them to the old set
6334 _old_set->add(r);
6335 }
6336 _total_used += r->used();
6337 }
6338
6339 return false;
6340 }
6341
6342 size_t total_used() {
6343 return _total_used;
6344 }
6345 };
6346
6347 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6348 assert_at_safepoint(true /* should_be_vm_thread */);
6349
6350 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6351 heap_region_iterate(&cl);
6352
6353 if (!free_list_only) {
6354 _summary_bytes_used = cl.total_used();
6355 }
6356 assert(_summary_bytes_used == recalculate_used(),
6357 err_msg("inconsistent _summary_bytes_used, "
6358 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6359 _summary_bytes_used, recalculate_used()));
6360 }
6361
6362 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6363 _refine_cte_cl->set_concurrent(concurrent);
6364 }
6365
6366 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6367 HeapRegion* hr = heap_region_containing(p);
6368 if (hr == NULL) {
6369 return false;
6370 } else {
6371 return hr->is_in(p);
6372 }
6373 }
6374
6375 // Methods for the mutator alloc region
6376
6377 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6378 bool force) {
6379 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6380 assert(!force || g1_policy()->can_expand_young_list(),
6381 "if force is true we should be able to expand the young list");
6382 bool young_list_full = g1_policy()->is_young_list_full();
6383 if (force || !young_list_full) {
6384 HeapRegion* new_alloc_region = new_region(word_size,
6385 false /* do_expand */);
6386 if (new_alloc_region != NULL) {
6387 set_region_short_lived_locked(new_alloc_region);
6388 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6389 return new_alloc_region;
6390 }
6391 }
6392 return NULL;
6393 }
6394
6395 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6396 size_t allocated_bytes) {
6397 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6398 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6399
6400 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6401 _summary_bytes_used += allocated_bytes;
6402 _hr_printer.retire(alloc_region);
6403 // We update the eden sizes here, when the region is retired,
6404 // instead of when it's allocated, since this is the point that its
6405 // used space has been recored in _summary_bytes_used.
6406 g1mm()->update_eden_size();
6407 }
6408
6409 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6410 bool force) {
6411 return _g1h->new_mutator_alloc_region(word_size, force);
6412 }
6413
6414 void G1CollectedHeap::set_par_threads() {
6415 // Don't change the number of workers. Use the value previously set
6416 // in the workgroup.
6417 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6418 uint n_workers = workers()->active_workers();
6419 assert(UseDynamicNumberOfGCThreads ||
6420 n_workers == workers()->total_workers(),
6421 "Otherwise should be using the total number of workers");
6422 if (n_workers == 0) {
6423 assert(false, "Should have been set in prior evacuation pause.");
6424 n_workers = ParallelGCThreads;
6425 workers()->set_active_workers(n_workers);
6426 }
6427 set_par_threads(n_workers);
6428 }
6429
6430 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6431 size_t allocated_bytes) {
6432 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6433 }
6434
6435 // Methods for the GC alloc regions
6436
6437 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6438 uint count,
6439 GCAllocPurpose ap) {
6440 assert(FreeList_lock->owned_by_self(), "pre-condition");
6441
6442 if (count < g1_policy()->max_regions(ap)) {
6443 HeapRegion* new_alloc_region = new_region(word_size,
6444 true /* do_expand */);
6445 if (new_alloc_region != NULL) {
6446 // We really only need to do this for old regions given that we
6447 // should never scan survivors. But it doesn't hurt to do it
6448 // for survivors too.
6449 new_alloc_region->set_saved_mark();
6450 if (ap == GCAllocForSurvived) {
6451 new_alloc_region->set_survivor();
6452 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6453 } else {
6454 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6455 }
6456 bool during_im = g1_policy()->during_initial_mark_pause();
6457 new_alloc_region->note_start_of_copying(during_im);
6458 return new_alloc_region;
6459 } else {
6460 g1_policy()->note_alloc_region_limit_reached(ap);
6461 }
6462 }
6463 return NULL;
6464 }
6465
6466 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6467 size_t allocated_bytes,
6468 GCAllocPurpose ap) {
6469 bool during_im = g1_policy()->during_initial_mark_pause();
6470 alloc_region->note_end_of_copying(during_im);
6471 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6472 if (ap == GCAllocForSurvived) {
6473 young_list()->add_survivor_region(alloc_region);
6474 } else {
6475 _old_set.add(alloc_region);
6476 }
6477 _hr_printer.retire(alloc_region);
6478 }
6479
6480 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6481 bool force) {
6482 assert(!force, "not supported for GC alloc regions");
6483 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6484 }
6485
6486 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6487 size_t allocated_bytes) {
6488 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6489 GCAllocForSurvived);
6490 }
6491
6492 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6493 bool force) {
6494 assert(!force, "not supported for GC alloc regions");
6495 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6496 }
6497
6498 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6499 size_t allocated_bytes) {
6500 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6501 GCAllocForTenured);
6502 }
6503 // Heap region set verification
6504
6505 class VerifyRegionListsClosure : public HeapRegionClosure {
6506 private:
6507 FreeRegionList* _free_list;
6508 OldRegionSet* _old_set;
6509 HumongousRegionSet* _humongous_set;
6510 uint _region_count;
6511
6512 public:
6513 VerifyRegionListsClosure(OldRegionSet* old_set,
6514 HumongousRegionSet* humongous_set,
6515 FreeRegionList* free_list) :
6516 _old_set(old_set), _humongous_set(humongous_set),
6517 _free_list(free_list), _region_count(0) { }
6518
6519 uint region_count() { return _region_count; }
6520
6521 bool doHeapRegion(HeapRegion* hr) {
6522 _region_count += 1;
6523
6524 if (hr->continuesHumongous()) {
6525 return false;
6526 }
6527
6528 if (hr->is_young()) {
6529 // TODO
6530 } else if (hr->startsHumongous()) {
6531 _humongous_set->verify_next_region(hr);
6532 } else if (hr->is_empty()) {
6533 _free_list->verify_next_region(hr);
6534 } else {
6535 _old_set->verify_next_region(hr);
6536 }
6537 return false;
6538 }
6539 };
6540
6541 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6542 HeapWord* bottom) {
6543 HeapWord* end = bottom + HeapRegion::GrainWords;
6544 MemRegion mr(bottom, end);
6545 assert(_g1_reserved.contains(mr), "invariant");
6546 // This might return NULL if the allocation fails
6547 return new HeapRegion(hrs_index, _bot_shared, mr);
6548 }
6549
6550 void G1CollectedHeap::verify_region_sets() {
6551 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6552
6553 // First, check the explicit lists.
6554 _free_list.verify();
6555 {
6556 // Given that a concurrent operation might be adding regions to
6557 // the secondary free list we have to take the lock before
6558 // verifying it.
6559 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6560 _secondary_free_list.verify();
6561 }
6562 _old_set.verify();
6563 _humongous_set.verify();
6564
6565 // If a concurrent region freeing operation is in progress it will
6566 // be difficult to correctly attributed any free regions we come
6567 // across to the correct free list given that they might belong to
6568 // one of several (free_list, secondary_free_list, any local lists,
6569 // etc.). So, if that's the case we will skip the rest of the
6570 // verification operation. Alternatively, waiting for the concurrent
6571 // operation to complete will have a non-trivial effect on the GC's
6572 // operation (no concurrent operation will last longer than the
6573 // interval between two calls to verification) and it might hide
6574 // any issues that we would like to catch during testing.
6575 if (free_regions_coming()) {
6576 return;
6577 }
6578
6579 // Make sure we append the secondary_free_list on the free_list so
6580 // that all free regions we will come across can be safely
6581 // attributed to the free_list.
6582 append_secondary_free_list_if_not_empty_with_lock();
6583
6584 // Finally, make sure that the region accounting in the lists is
6585 // consistent with what we see in the heap.
6586 _old_set.verify_start();
6587 _humongous_set.verify_start();
6588 _free_list.verify_start();
6589
6590 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6591 heap_region_iterate(&cl);
6592
6593 _old_set.verify_end();
6594 _humongous_set.verify_end();
6595 _free_list.verify_end();
6596 }