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/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1YCTypes.hpp"
43 #include "gc_implementation/g1/heapRegion.inline.hpp"
44 #include "gc_implementation/g1/heapRegionRemSet.hpp"
45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
46 #include "gc_implementation/g1/vm_operations_g1.hpp"
47 #include "gc_implementation/shared/gcHeapSummary.hpp"
48 #include "gc_implementation/shared/gcTimer.hpp"
49 #include "gc_implementation/shared/gcTrace.hpp"
50 #include "gc_implementation/shared/gcTraceTime.hpp"
51 #include "gc_implementation/shared/isGCActiveMark.hpp"
52 #include "memory/gcLocker.inline.hpp"
53 #include "memory/genOopClosures.inline.hpp"
54 #include "memory/generationSpec.hpp"
55 #include "memory/referenceProcessor.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/oop.pcgc.inline.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
1182 bool doHeapRegion(HeapRegion* r) {
1183 HeapRegionRemSet* hrrs = r->rem_set();
1184
1185 if (r->continuesHumongous()) {
1186 // We'll assert that the strong code root list and RSet is empty
1187 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1188 assert(hrrs->occupied() == 0, "RSet should be empty");
1189 return false;
1190 }
1191
1192 _g1h->reset_gc_time_stamps(r);
1193 hrrs->clear();
1194 // You might think here that we could clear just the cards
1195 // corresponding to the used region. But no: if we leave a dirty card
1196 // in a region we might allocate into, then it would prevent that card
1197 // from being enqueued, and cause it to be missed.
1198 // Re: the performance cost: we shouldn't be doing full GC anyway!
1199 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1200
1201 return false;
1202 }
1203 };
1204
1205 void G1CollectedHeap::clear_rsets_post_compaction() {
1206 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1207 heap_region_iterate(&rs_clear);
1208 }
1209
1210 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1211 G1CollectedHeap* _g1h;
1212 UpdateRSOopClosure _cl;
1213 int _worker_i;
1214 public:
1215 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1216 _cl(g1->g1_rem_set(), worker_i),
1217 _worker_i(worker_i),
1218 _g1h(g1)
1219 { }
1220
1221 bool doHeapRegion(HeapRegion* r) {
1222 if (!r->continuesHumongous()) {
1223 _cl.set_from(r);
1224 r->oop_iterate(&_cl);
1225 }
1226 return false;
1227 }
1228 };
1229
1230 class ParRebuildRSTask: public AbstractGangTask {
1231 G1CollectedHeap* _g1;
1232 public:
1233 ParRebuildRSTask(G1CollectedHeap* g1)
1234 : AbstractGangTask("ParRebuildRSTask"),
1235 _g1(g1)
1236 { }
1237
1238 void work(uint worker_id) {
1239 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1240 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1241 _g1->workers()->active_workers(),
1242 HeapRegion::RebuildRSClaimValue);
1243 }
1244 };
1245
1246 class PostCompactionPrinterClosure: public HeapRegionClosure {
1247 private:
1248 G1HRPrinter* _hr_printer;
1249 public:
1250 bool doHeapRegion(HeapRegion* hr) {
1251 assert(!hr->is_young(), "not expecting to find young regions");
1252 // We only generate output for non-empty regions.
1253 if (!hr->is_empty()) {
1254 if (!hr->isHumongous()) {
1255 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1256 } else if (hr->startsHumongous()) {
1257 if (hr->region_num() == 1) {
1258 // single humongous region
1259 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1260 } else {
1261 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1262 }
1263 } else {
1264 assert(hr->continuesHumongous(), "only way to get here");
1265 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1266 }
1267 }
1268 return false;
1269 }
1270
1271 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1272 : _hr_printer(hr_printer) { }
1273 };
1274
1275 void G1CollectedHeap::print_hrs_post_compaction() {
1276 PostCompactionPrinterClosure cl(hr_printer());
1277 heap_region_iterate(&cl);
1278 }
1279
1280 bool G1CollectedHeap::do_collection(bool explicit_gc,
1281 bool clear_all_soft_refs,
1282 size_t word_size) {
1283 assert_at_safepoint(true /* should_be_vm_thread */);
1284
1285 if (GC_locker::check_active_before_gc()) {
1286 return false;
1287 }
1288
1289 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1290 gc_timer->register_gc_start(os::elapsed_counter());
1291
1292 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1293 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1294
1295 SvcGCMarker sgcm(SvcGCMarker::FULL);
1296 ResourceMark rm;
1297
1298 print_heap_before_gc();
1299 trace_heap_before_gc(gc_tracer);
1300
1301 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1302
1303 HRSPhaseSetter x(HRSPhaseFullGC);
1304 verify_region_sets_optional();
1305
1306 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1307 collector_policy()->should_clear_all_soft_refs();
1308
1309 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1310
1311 {
1312 IsGCActiveMark x;
1313
1314 // Timing
1315 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1316 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1317 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1318
1319 {
1320 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1321 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1322 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1323
1324 double start = os::elapsedTime();
1325 g1_policy()->record_full_collection_start();
1326
1327 // Note: When we have a more flexible GC logging framework that
1328 // allows us to add optional attributes to a GC log record we
1329 // could consider timing and reporting how long we wait in the
1330 // following two methods.
1331 wait_while_free_regions_coming();
1332 // If we start the compaction before the CM threads finish
1333 // scanning the root regions we might trip them over as we'll
1334 // be moving objects / updating references. So let's wait until
1335 // they are done. By telling them to abort, they should complete
1336 // early.
1337 _cm->root_regions()->abort();
1338 _cm->root_regions()->wait_until_scan_finished();
1339 append_secondary_free_list_if_not_empty_with_lock();
1340
1341 gc_prologue(true);
1342 increment_total_collections(true /* full gc */);
1343 increment_old_marking_cycles_started();
1344
1345 assert(used() == recalculate_used(), "Should be equal");
1346
1347 verify_before_gc();
1348
1349 pre_full_gc_dump(gc_timer);
1350
1351 COMPILER2_PRESENT(DerivedPointerTable::clear());
1352
1353 // Disable discovery and empty the discovered lists
1354 // for the CM ref processor.
1355 ref_processor_cm()->disable_discovery();
1356 ref_processor_cm()->abandon_partial_discovery();
1357 ref_processor_cm()->verify_no_references_recorded();
1358
1359 // Abandon current iterations of concurrent marking and concurrent
1360 // refinement, if any are in progress. We have to do this before
1361 // wait_until_scan_finished() below.
1362 concurrent_mark()->abort();
1363
1364 // Make sure we'll choose a new allocation region afterwards.
1365 release_mutator_alloc_region();
1366 abandon_gc_alloc_regions();
1367 g1_rem_set()->cleanupHRRS();
1368
1369 // We should call this after we retire any currently active alloc
1370 // regions so that all the ALLOC / RETIRE events are generated
1371 // before the start GC event.
1372 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1373
1374 // We may have added regions to the current incremental collection
1375 // set between the last GC or pause and now. We need to clear the
1376 // incremental collection set and then start rebuilding it afresh
1377 // after this full GC.
1378 abandon_collection_set(g1_policy()->inc_cset_head());
1379 g1_policy()->clear_incremental_cset();
1380 g1_policy()->stop_incremental_cset_building();
1381
1382 tear_down_region_sets(false /* free_list_only */);
1383 g1_policy()->set_gcs_are_young(true);
1384
1385 // See the comments in g1CollectedHeap.hpp and
1386 // G1CollectedHeap::ref_processing_init() about
1387 // how reference processing currently works in G1.
1388
1389 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1390 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1391
1392 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1393 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1394
1395 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1396 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1397
1398 // Do collection work
1399 {
1400 HandleMark hm; // Discard invalid handles created during gc
1401 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1402 }
1403
1404 assert(free_regions() == 0, "we should not have added any free regions");
1405 rebuild_region_sets(false /* free_list_only */);
1406
1407 // Enqueue any discovered reference objects that have
1408 // not been removed from the discovered lists.
1409 ref_processor_stw()->enqueue_discovered_references();
1410
1411 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1412
1413 MemoryService::track_memory_usage();
1414
1415 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1416 ref_processor_stw()->verify_no_references_recorded();
1417
1418 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1419 ClassLoaderDataGraph::purge();
1420 MetaspaceAux::verify_metrics();
1421
1422 // Note: since we've just done a full GC, concurrent
1423 // marking is no longer active. Therefore we need not
1424 // re-enable reference discovery for the CM ref processor.
1425 // That will be done at the start of the next marking cycle.
1426 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1427 ref_processor_cm()->verify_no_references_recorded();
1428
1429 reset_gc_time_stamp();
1430 // Since everything potentially moved, we will clear all remembered
1431 // sets, and clear all cards. Later we will rebuild remembered
1432 // sets. We will also reset the GC time stamps of the regions.
1433 clear_rsets_post_compaction();
1434 check_gc_time_stamps();
1435
1436 // Resize the heap if necessary.
1437 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1438
1439 if (_hr_printer.is_active()) {
1440 // We should do this after we potentially resize the heap so
1441 // that all the COMMIT / UNCOMMIT events are generated before
1442 // the end GC event.
1443
1444 print_hrs_post_compaction();
1445 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1446 }
1447
1448 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1449 if (hot_card_cache->use_cache()) {
1450 hot_card_cache->reset_card_counts();
1451 hot_card_cache->reset_hot_cache();
1452 }
1453
1454 // Rebuild remembered sets of all regions.
1455 if (G1CollectedHeap::use_parallel_gc_threads()) {
1456 uint n_workers =
1457 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1458 workers()->active_workers(),
1459 Threads::number_of_non_daemon_threads());
1460 assert(UseDynamicNumberOfGCThreads ||
1461 n_workers == workers()->total_workers(),
1462 "If not dynamic should be using all the workers");
1463 workers()->set_active_workers(n_workers);
1464 // Set parallel threads in the heap (_n_par_threads) only
1465 // before a parallel phase and always reset it to 0 after
1466 // the phase so that the number of parallel threads does
1467 // no get carried forward to a serial phase where there
1468 // may be code that is "possibly_parallel".
1469 set_par_threads(n_workers);
1470
1471 ParRebuildRSTask rebuild_rs_task(this);
1472 assert(check_heap_region_claim_values(
1473 HeapRegion::InitialClaimValue), "sanity check");
1474 assert(UseDynamicNumberOfGCThreads ||
1475 workers()->active_workers() == workers()->total_workers(),
1476 "Unless dynamic should use total workers");
1477 // Use the most recent number of active workers
1478 assert(workers()->active_workers() > 0,
1479 "Active workers not properly set");
1480 set_par_threads(workers()->active_workers());
1481 workers()->run_task(&rebuild_rs_task);
1482 set_par_threads(0);
1483 assert(check_heap_region_claim_values(
1484 HeapRegion::RebuildRSClaimValue), "sanity check");
1485 reset_heap_region_claim_values();
1486 } else {
1487 RebuildRSOutOfRegionClosure rebuild_rs(this);
1488 heap_region_iterate(&rebuild_rs);
1489 }
1490
1491 // Rebuild the strong code root lists for each region
1492 rebuild_strong_code_roots();
1493
1494 if (true) { // FIXME
1495 MetaspaceGC::compute_new_size();
1496 }
1497
1498 #ifdef TRACESPINNING
1499 ParallelTaskTerminator::print_termination_counts();
1500 #endif
1501
1502 // Discard all rset updates
1503 JavaThread::dirty_card_queue_set().abandon_logs();
1504 assert(!G1DeferredRSUpdate
1505 || (G1DeferredRSUpdate &&
1506 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1507
1508 _young_list->reset_sampled_info();
1509 // At this point there should be no regions in the
1510 // entire heap tagged as young.
1511 assert(check_young_list_empty(true /* check_heap */),
1512 "young list should be empty at this point");
1513
1514 // Update the number of full collections that have been completed.
1515 increment_old_marking_cycles_completed(false /* concurrent */);
1516
1517 _hrs.verify_optional();
1518 verify_region_sets_optional();
1519
1520 verify_after_gc();
1521
1522 // Start a new incremental collection set for the next pause
1523 assert(g1_policy()->collection_set() == NULL, "must be");
1524 g1_policy()->start_incremental_cset_building();
1525
1526 // Clear the _cset_fast_test bitmap in anticipation of adding
1527 // regions to the incremental collection set for the next
1528 // evacuation pause.
1529 clear_cset_fast_test();
1530
1531 init_mutator_alloc_region();
1532
1533 double end = os::elapsedTime();
1534 g1_policy()->record_full_collection_end();
1535
1536 if (G1Log::fine()) {
1537 g1_policy()->print_heap_transition();
1538 }
1539
1540 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1541 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1542 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1543 // before any GC notifications are raised.
1544 g1mm()->update_sizes();
1545
1546 gc_epilogue(true);
1547 }
1548
1549 if (G1Log::finer()) {
1550 g1_policy()->print_detailed_heap_transition(true /* full */);
1551 }
1552
1553 print_heap_after_gc();
1554 trace_heap_after_gc(gc_tracer);
1555
1556 post_full_gc_dump(gc_timer);
1557
1558 gc_timer->register_gc_end(os::elapsed_counter());
1559 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1560 }
1561
1562 return true;
1563 }
1564
1565 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1566 // do_collection() will return whether it succeeded in performing
1567 // the GC. Currently, there is no facility on the
1568 // do_full_collection() API to notify the caller than the collection
1569 // did not succeed (e.g., because it was locked out by the GC
1570 // locker). So, right now, we'll ignore the return value.
1571 bool dummy = do_collection(true, /* explicit_gc */
1572 clear_all_soft_refs,
1573 0 /* word_size */);
1574 }
1575
1576 // This code is mostly copied from TenuredGeneration.
1577 void
1578 G1CollectedHeap::
1579 resize_if_necessary_after_full_collection(size_t word_size) {
1580 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1581
1582 // Include the current allocation, if any, and bytes that will be
1583 // pre-allocated to support collections, as "used".
1584 const size_t used_after_gc = used();
1585 const size_t capacity_after_gc = capacity();
1586 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1587
1588 // This is enforced in arguments.cpp.
1589 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1590 "otherwise the code below doesn't make sense");
1591
1592 // We don't have floating point command-line arguments
1593 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1594 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1595 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1596 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1597
1598 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1599 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1600
1601 // We have to be careful here as these two calculations can overflow
1602 // 32-bit size_t's.
1603 double used_after_gc_d = (double) used_after_gc;
1604 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1605 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1606
1607 // Let's make sure that they are both under the max heap size, which
1608 // by default will make them fit into a size_t.
1609 double desired_capacity_upper_bound = (double) max_heap_size;
1610 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1611 desired_capacity_upper_bound);
1612 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1613 desired_capacity_upper_bound);
1614
1615 // We can now safely turn them into size_t's.
1616 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1617 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1618
1619 // This assert only makes sense here, before we adjust them
1620 // with respect to the min and max heap size.
1621 assert(minimum_desired_capacity <= maximum_desired_capacity,
1622 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1623 "maximum_desired_capacity = "SIZE_FORMAT,
1624 minimum_desired_capacity, maximum_desired_capacity));
1625
1626 // Should not be greater than the heap max size. No need to adjust
1627 // it with respect to the heap min size as it's a lower bound (i.e.,
1628 // we'll try to make the capacity larger than it, not smaller).
1629 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1630 // Should not be less than the heap min size. No need to adjust it
1631 // with respect to the heap max size as it's an upper bound (i.e.,
1632 // we'll try to make the capacity smaller than it, not greater).
1633 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1634
1635 if (capacity_after_gc < minimum_desired_capacity) {
1636 // Don't expand unless it's significant
1637 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1638 ergo_verbose4(ErgoHeapSizing,
1639 "attempt heap expansion",
1640 ergo_format_reason("capacity lower than "
1641 "min desired capacity after Full GC")
1642 ergo_format_byte("capacity")
1643 ergo_format_byte("occupancy")
1644 ergo_format_byte_perc("min desired capacity"),
1645 capacity_after_gc, used_after_gc,
1646 minimum_desired_capacity, (double) MinHeapFreeRatio);
1647 expand(expand_bytes);
1648
1649 // No expansion, now see if we want to shrink
1650 } else if (capacity_after_gc > maximum_desired_capacity) {
1651 // Capacity too large, compute shrinking size
1652 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1653 ergo_verbose4(ErgoHeapSizing,
1654 "attempt heap shrinking",
1655 ergo_format_reason("capacity higher than "
1656 "max desired capacity after Full GC")
1657 ergo_format_byte("capacity")
1658 ergo_format_byte("occupancy")
1659 ergo_format_byte_perc("max desired capacity"),
1660 capacity_after_gc, used_after_gc,
1661 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1662 shrink(shrink_bytes);
1663 }
1664 }
1665
1666
1667 HeapWord*
1668 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1669 bool* succeeded) {
1670 assert_at_safepoint(true /* should_be_vm_thread */);
1671
1672 *succeeded = true;
1673 // Let's attempt the allocation first.
1674 HeapWord* result =
1675 attempt_allocation_at_safepoint(word_size,
1676 false /* expect_null_mutator_alloc_region */);
1677 if (result != NULL) {
1678 assert(*succeeded, "sanity");
1679 return result;
1680 }
1681
1682 // In a G1 heap, we're supposed to keep allocation from failing by
1683 // incremental pauses. Therefore, at least for now, we'll favor
1684 // expansion over collection. (This might change in the future if we can
1685 // do something smarter than full collection to satisfy a failed alloc.)
1686 result = expand_and_allocate(word_size);
1687 if (result != NULL) {
1688 assert(*succeeded, "sanity");
1689 return result;
1690 }
1691
1692 // Expansion didn't work, we'll try to do a Full GC.
1693 bool gc_succeeded = do_collection(false, /* explicit_gc */
1694 false, /* clear_all_soft_refs */
1695 word_size);
1696 if (!gc_succeeded) {
1697 *succeeded = false;
1698 return NULL;
1699 }
1700
1701 // Retry the allocation
1702 result = attempt_allocation_at_safepoint(word_size,
1703 true /* expect_null_mutator_alloc_region */);
1704 if (result != NULL) {
1705 assert(*succeeded, "sanity");
1706 return result;
1707 }
1708
1709 // Then, try a Full GC that will collect all soft references.
1710 gc_succeeded = do_collection(false, /* explicit_gc */
1711 true, /* clear_all_soft_refs */
1712 word_size);
1713 if (!gc_succeeded) {
1714 *succeeded = false;
1715 return NULL;
1716 }
1717
1718 // Retry the allocation once more
1719 result = attempt_allocation_at_safepoint(word_size,
1720 true /* expect_null_mutator_alloc_region */);
1721 if (result != NULL) {
1722 assert(*succeeded, "sanity");
1723 return result;
1724 }
1725
1726 assert(!collector_policy()->should_clear_all_soft_refs(),
1727 "Flag should have been handled and cleared prior to this point");
1728
1729 // What else? We might try synchronous finalization later. If the total
1730 // space available is large enough for the allocation, then a more
1731 // complete compaction phase than we've tried so far might be
1732 // appropriate.
1733 assert(*succeeded, "sanity");
1734 return NULL;
1735 }
1736
1737 // Attempting to expand the heap sufficiently
1738 // to support an allocation of the given "word_size". If
1739 // successful, perform the allocation and return the address of the
1740 // allocated block, or else "NULL".
1741
1742 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1743 assert_at_safepoint(true /* should_be_vm_thread */);
1744
1745 verify_region_sets_optional();
1746
1747 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1748 ergo_verbose1(ErgoHeapSizing,
1749 "attempt heap expansion",
1750 ergo_format_reason("allocation request failed")
1751 ergo_format_byte("allocation request"),
1752 word_size * HeapWordSize);
1753 if (expand(expand_bytes)) {
1754 _hrs.verify_optional();
1755 verify_region_sets_optional();
1756 return attempt_allocation_at_safepoint(word_size,
1757 false /* expect_null_mutator_alloc_region */);
1758 }
1759 return NULL;
1760 }
1761
1762 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1763 HeapWord* new_end) {
1764 assert(old_end != new_end, "don't call this otherwise");
1765 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1766
1767 // Update the committed mem region.
1768 _g1_committed.set_end(new_end);
1769 // Tell the card table about the update.
1770 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1771 // Tell the BOT about the update.
1772 _bot_shared->resize(_g1_committed.word_size());
1773 // Tell the hot card cache about the update
1774 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1775 }
1776
1777 bool G1CollectedHeap::expand(size_t expand_bytes) {
1778 size_t old_mem_size = _g1_storage.committed_size();
1779 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1780 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1781 HeapRegion::GrainBytes);
1782 ergo_verbose2(ErgoHeapSizing,
1783 "expand the heap",
1784 ergo_format_byte("requested expansion amount")
1785 ergo_format_byte("attempted expansion amount"),
1786 expand_bytes, aligned_expand_bytes);
1787
1788 // First commit the memory.
1789 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1790 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1791 if (successful) {
1792 // Then propagate this update to the necessary data structures.
1793 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1794 update_committed_space(old_end, new_end);
1795
1796 FreeRegionList expansion_list("Local Expansion List");
1797 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1798 assert(mr.start() == old_end, "post-condition");
1799 // mr might be a smaller region than what was requested if
1800 // expand_by() was unable to allocate the HeapRegion instances
1801 assert(mr.end() <= new_end, "post-condition");
1802
1803 size_t actual_expand_bytes = mr.byte_size();
1804 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1805 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1806 "post-condition");
1807 if (actual_expand_bytes < aligned_expand_bytes) {
1808 // We could not expand _hrs to the desired size. In this case we
1809 // need to shrink the committed space accordingly.
1810 assert(mr.end() < new_end, "invariant");
1811
1812 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1813 // First uncommit the memory.
1814 _g1_storage.shrink_by(diff_bytes);
1815 // Then propagate this update to the necessary data structures.
1816 update_committed_space(new_end, mr.end());
1817 }
1818 _free_list.add_as_tail(&expansion_list);
1819
1820 if (_hr_printer.is_active()) {
1821 HeapWord* curr = mr.start();
1822 while (curr < mr.end()) {
1823 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1824 _hr_printer.commit(curr, curr_end);
1825 curr = curr_end;
1826 }
1827 assert(curr == mr.end(), "post-condition");
1828 }
1829 g1_policy()->record_new_heap_size(n_regions());
1830 } else {
1831 ergo_verbose0(ErgoHeapSizing,
1832 "did not expand the heap",
1833 ergo_format_reason("heap expansion operation failed"));
1834 // The expansion of the virtual storage space was unsuccessful.
1835 // Let's see if it was because we ran out of swap.
1836 if (G1ExitOnExpansionFailure &&
1837 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1838 // We had head room...
1839 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1840 }
1841 }
1842 return successful;
1843 }
1844
1845 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1846 size_t old_mem_size = _g1_storage.committed_size();
1847 size_t aligned_shrink_bytes =
1848 ReservedSpace::page_align_size_down(shrink_bytes);
1849 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1850 HeapRegion::GrainBytes);
1851 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1852
1853 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1854 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1855 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1856
1857 ergo_verbose3(ErgoHeapSizing,
1858 "shrink the heap",
1859 ergo_format_byte("requested shrinking amount")
1860 ergo_format_byte("aligned shrinking amount")
1861 ergo_format_byte("attempted shrinking amount"),
1862 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1863 if (num_regions_removed > 0) {
1864 _g1_storage.shrink_by(shrunk_bytes);
1865 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1866
1867 if (_hr_printer.is_active()) {
1868 HeapWord* curr = old_end;
1869 while (curr > new_end) {
1870 HeapWord* curr_end = curr;
1871 curr -= HeapRegion::GrainWords;
1872 _hr_printer.uncommit(curr, curr_end);
1873 }
1874 }
1875
1876 _expansion_regions += num_regions_removed;
1877 update_committed_space(old_end, new_end);
1878 HeapRegionRemSet::shrink_heap(n_regions());
1879 g1_policy()->record_new_heap_size(n_regions());
1880 } else {
1881 ergo_verbose0(ErgoHeapSizing,
1882 "did not shrink the heap",
1883 ergo_format_reason("heap shrinking operation failed"));
1884 }
1885 }
1886
1887 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1888 verify_region_sets_optional();
1889
1890 // We should only reach here at the end of a Full GC which means we
1891 // should not not be holding to any GC alloc regions. The method
1892 // below will make sure of that and do any remaining clean up.
1893 abandon_gc_alloc_regions();
1894
1895 // Instead of tearing down / rebuilding the free lists here, we
1896 // could instead use the remove_all_pending() method on free_list to
1897 // remove only the ones that we need to remove.
1898 tear_down_region_sets(true /* free_list_only */);
1899 shrink_helper(shrink_bytes);
1900 rebuild_region_sets(true /* free_list_only */);
1901
1902 _hrs.verify_optional();
1903 verify_region_sets_optional();
1904 }
1905
1906 // Public methods.
1907
1908 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1909 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1910 #endif // _MSC_VER
1911
1912
1913 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1914 SharedHeap(policy_),
1915 _g1_policy(policy_),
1916 _dirty_card_queue_set(false),
1917 _into_cset_dirty_card_queue_set(false),
1918 _is_alive_closure_cm(this),
1919 _is_alive_closure_stw(this),
1920 _ref_processor_cm(NULL),
1921 _ref_processor_stw(NULL),
1922 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1923 _bot_shared(NULL),
1924 _evac_failure_scan_stack(NULL),
1925 _mark_in_progress(false),
1926 _cg1r(NULL), _summary_bytes_used(0),
1927 _g1mm(NULL),
1928 _refine_cte_cl(NULL),
1929 _full_collection(false),
1930 _free_list("Master Free List"),
1931 _secondary_free_list("Secondary Free List"),
1932 _old_set("Old Set"),
1933 _humongous_set("Master Humongous Set"),
1934 _free_regions_coming(false),
1935 _young_list(new YoungList(this)),
1936 _gc_time_stamp(0),
1937 _retained_old_gc_alloc_region(NULL),
1938 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1939 _old_plab_stats(OldPLABSize, PLABWeight),
1940 _expand_heap_after_alloc_failure(true),
1941 _surviving_young_words(NULL),
1942 _old_marking_cycles_started(0),
1943 _old_marking_cycles_completed(0),
1944 _concurrent_cycle_started(false),
1945 _in_cset_fast_test(NULL),
1946 _in_cset_fast_test_base(NULL),
1947 _dirty_cards_region_list(NULL),
1948 _worker_cset_start_region(NULL),
1949 _worker_cset_start_region_time_stamp(NULL),
1950 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1951 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1952 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1953 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1954
1955 _g1h = this;
1956 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1957 vm_exit_during_initialization("Failed necessary allocation.");
1958 }
1959
1960 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1961
1962 int n_queues = MAX2((int)ParallelGCThreads, 1);
1963 _task_queues = new RefToScanQueueSet(n_queues);
1964
1965 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1966 assert(n_rem_sets > 0, "Invariant.");
1967
1968 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1969 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1970 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1971
1972 for (int i = 0; i < n_queues; i++) {
1973 RefToScanQueue* q = new RefToScanQueue();
1974 q->initialize();
1975 _task_queues->register_queue(i, q);
1976 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1977 }
1978 clear_cset_start_regions();
1979
1980 // Initialize the G1EvacuationFailureALot counters and flags.
1981 NOT_PRODUCT(reset_evacuation_should_fail();)
1982
1983 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1984 }
1985
1986 jint G1CollectedHeap::initialize() {
1987 CollectedHeap::pre_initialize();
1988 os::enable_vtime();
1989
1990 G1Log::init();
1991
1992 // Necessary to satisfy locking discipline assertions.
1993
1994 MutexLocker x(Heap_lock);
1995
1996 // We have to initialize the printer before committing the heap, as
1997 // it will be used then.
1998 _hr_printer.set_active(G1PrintHeapRegions);
1999
2000 // While there are no constraints in the GC code that HeapWordSize
2001 // be any particular value, there are multiple other areas in the
2002 // system which believe this to be true (e.g. oop->object_size in some
2003 // cases incorrectly returns the size in wordSize units rather than
2004 // HeapWordSize).
2005 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2006
2007 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2008 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2009 size_t heap_alignment = collector_policy()->max_alignment();
2010
2011 // Ensure that the sizes are properly aligned.
2012 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2013 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2014 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2015
2016 _cg1r = new ConcurrentG1Refine(this);
2017
2018 // Reserve the maximum.
2019
2020 // When compressed oops are enabled, the preferred heap base
2021 // is calculated by subtracting the requested size from the
2022 // 32Gb boundary and using the result as the base address for
2023 // heap reservation. If the requested size is not aligned to
2024 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2025 // into the ReservedHeapSpace constructor) then the actual
2026 // base of the reserved heap may end up differing from the
2027 // address that was requested (i.e. the preferred heap base).
2028 // If this happens then we could end up using a non-optimal
2029 // compressed oops mode.
2030
2031 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2032 heap_alignment);
2033
2034 // It is important to do this in a way such that concurrent readers can't
2035 // temporarily think something is in the heap. (I've actually seen this
2036 // happen in asserts: DLD.)
2037 _reserved.set_word_size(0);
2038 _reserved.set_start((HeapWord*)heap_rs.base());
2039 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2040
2041 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2042
2043 // Create the gen rem set (and barrier set) for the entire reserved region.
2044 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2045 set_barrier_set(rem_set()->bs());
2046 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2047 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2048 } else {
2049 vm_exit_during_initialization("G1 requires a mod ref bs.");
2050 return JNI_ENOMEM;
2051 }
2052
2053 // Also create a G1 rem set.
2054 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2055 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2056 } else {
2057 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2058 return JNI_ENOMEM;
2059 }
2060
2061 // Carve out the G1 part of the heap.
2062
2063 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2064 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2065 g1_rs.size()/HeapWordSize);
2066
2067 _g1_storage.initialize(g1_rs, 0);
2068 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2069 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2070 (HeapWord*) _g1_reserved.end(),
2071 _expansion_regions);
2072
2073 // Do later initialization work for concurrent refinement.
2074 _cg1r->init();
2075
2076 // 6843694 - ensure that the maximum region index can fit
2077 // in the remembered set structures.
2078 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2079 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2080
2081 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2082 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2083 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2084 "too many cards per region");
2085
2086 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2087
2088 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2089 heap_word_size(init_byte_size));
2090
2091 _g1h = this;
2092
2093 _in_cset_fast_test_length = max_regions();
2094 _in_cset_fast_test_base =
2095 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2096
2097 // We're biasing _in_cset_fast_test to avoid subtracting the
2098 // beginning of the heap every time we want to index; basically
2099 // it's the same with what we do with the card table.
2100 _in_cset_fast_test = _in_cset_fast_test_base -
2101 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2102
2103 // Clear the _cset_fast_test bitmap in anticipation of adding
2104 // regions to the incremental collection set for the first
2105 // evacuation pause.
2106 clear_cset_fast_test();
2107
2108 // Create the ConcurrentMark data structure and thread.
2109 // (Must do this late, so that "max_regions" is defined.)
2110 _cm = new ConcurrentMark(this, heap_rs);
2111 if (_cm == NULL || !_cm->completed_initialization()) {
2112 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2113 return JNI_ENOMEM;
2114 }
2115 _cmThread = _cm->cmThread();
2116
2117 // Initialize the from_card cache structure of HeapRegionRemSet.
2118 HeapRegionRemSet::init_heap(max_regions());
2119
2120 // Now expand into the initial heap size.
2121 if (!expand(init_byte_size)) {
2122 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2123 return JNI_ENOMEM;
2124 }
2125
2126 // Perform any initialization actions delegated to the policy.
2127 g1_policy()->init();
2128
2129 _refine_cte_cl =
2130 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2131 g1_rem_set(),
2132 concurrent_g1_refine());
2133 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2134
2135 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2136 SATB_Q_FL_lock,
2137 G1SATBProcessCompletedThreshold,
2138 Shared_SATB_Q_lock);
2139
2140 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2141 DirtyCardQ_FL_lock,
2142 concurrent_g1_refine()->yellow_zone(),
2143 concurrent_g1_refine()->red_zone(),
2144 Shared_DirtyCardQ_lock);
2145
2146 if (G1DeferredRSUpdate) {
2147 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2148 DirtyCardQ_FL_lock,
2149 -1, // never trigger processing
2150 -1, // no limit on length
2151 Shared_DirtyCardQ_lock,
2152 &JavaThread::dirty_card_queue_set());
2153 }
2154
2155 // Initialize the card queue set used to hold cards containing
2156 // references into the collection set.
2157 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2158 DirtyCardQ_FL_lock,
2159 -1, // never trigger processing
2160 -1, // no limit on length
2161 Shared_DirtyCardQ_lock,
2162 &JavaThread::dirty_card_queue_set());
2163
2164 // In case we're keeping closure specialization stats, initialize those
2165 // counts and that mechanism.
2166 SpecializationStats::clear();
2167
2168 // Here we allocate the dummy full region that is required by the
2169 // G1AllocRegion class. If we don't pass an address in the reserved
2170 // space here, lots of asserts fire.
2171
2172 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2173 _g1_reserved.start());
2174 // We'll re-use the same region whether the alloc region will
2175 // require BOT updates or not and, if it doesn't, then a non-young
2176 // region will complain that it cannot support allocations without
2177 // BOT updates. So we'll tag the dummy region as young to avoid that.
2178 dummy_region->set_young();
2179 // Make sure it's full.
2180 dummy_region->set_top(dummy_region->end());
2181 G1AllocRegion::setup(this, dummy_region);
2182
2183 init_mutator_alloc_region();
2184
2185 // Do create of the monitoring and management support so that
2186 // values in the heap have been properly initialized.
2187 _g1mm = new G1MonitoringSupport(this);
2188
2189 return JNI_OK;
2190 }
2191
2192 void G1CollectedHeap::ref_processing_init() {
2193 // Reference processing in G1 currently works as follows:
2194 //
2195 // * There are two reference processor instances. One is
2196 // used to record and process discovered references
2197 // during concurrent marking; the other is used to
2198 // record and process references during STW pauses
2199 // (both full and incremental).
2200 // * Both ref processors need to 'span' the entire heap as
2201 // the regions in the collection set may be dotted around.
2202 //
2203 // * For the concurrent marking ref processor:
2204 // * Reference discovery is enabled at initial marking.
2205 // * Reference discovery is disabled and the discovered
2206 // references processed etc during remarking.
2207 // * Reference discovery is MT (see below).
2208 // * Reference discovery requires a barrier (see below).
2209 // * Reference processing may or may not be MT
2210 // (depending on the value of ParallelRefProcEnabled
2211 // and ParallelGCThreads).
2212 // * A full GC disables reference discovery by the CM
2213 // ref processor and abandons any entries on it's
2214 // discovered lists.
2215 //
2216 // * For the STW processor:
2217 // * Non MT discovery is enabled at the start of a full GC.
2218 // * Processing and enqueueing during a full GC is non-MT.
2219 // * During a full GC, references are processed after marking.
2220 //
2221 // * Discovery (may or may not be MT) is enabled at the start
2222 // of an incremental evacuation pause.
2223 // * References are processed near the end of a STW evacuation pause.
2224 // * For both types of GC:
2225 // * Discovery is atomic - i.e. not concurrent.
2226 // * Reference discovery will not need a barrier.
2227
2228 SharedHeap::ref_processing_init();
2229 MemRegion mr = reserved_region();
2230
2231 // Concurrent Mark ref processor
2232 _ref_processor_cm =
2233 new ReferenceProcessor(mr, // span
2234 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2235 // mt processing
2236 (int) ParallelGCThreads,
2237 // degree of mt processing
2238 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2239 // mt discovery
2240 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2241 // degree of mt discovery
2242 false,
2243 // Reference discovery is not atomic
2244 &_is_alive_closure_cm,
2245 // is alive closure
2246 // (for efficiency/performance)
2247 true);
2248 // Setting next fields of discovered
2249 // lists requires a barrier.
2250
2251 // STW ref processor
2252 _ref_processor_stw =
2253 new ReferenceProcessor(mr, // span
2254 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2255 // mt processing
2256 MAX2((int)ParallelGCThreads, 1),
2257 // degree of mt processing
2258 (ParallelGCThreads > 1),
2259 // mt discovery
2260 MAX2((int)ParallelGCThreads, 1),
2261 // degree of mt discovery
2262 true,
2263 // Reference discovery is atomic
2264 &_is_alive_closure_stw,
2265 // is alive closure
2266 // (for efficiency/performance)
2267 false);
2268 // Setting next fields of discovered
2269 // lists requires a barrier.
2270 }
2271
2272 size_t G1CollectedHeap::capacity() const {
2273 return _g1_committed.byte_size();
2274 }
2275
2276 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2277 assert(!hr->continuesHumongous(), "pre-condition");
2278 hr->reset_gc_time_stamp();
2279 if (hr->startsHumongous()) {
2280 uint first_index = hr->hrs_index() + 1;
2281 uint last_index = hr->last_hc_index();
2282 for (uint i = first_index; i < last_index; i += 1) {
2283 HeapRegion* chr = region_at(i);
2284 assert(chr->continuesHumongous(), "sanity");
2285 chr->reset_gc_time_stamp();
2286 }
2287 }
2288 }
2289
2290 #ifndef PRODUCT
2291 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2292 private:
2293 unsigned _gc_time_stamp;
2294 bool _failures;
2295
2296 public:
2297 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2298 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2299
2300 virtual bool doHeapRegion(HeapRegion* hr) {
2301 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2302 if (_gc_time_stamp != region_gc_time_stamp) {
2303 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2304 "expected %d", HR_FORMAT_PARAMS(hr),
2305 region_gc_time_stamp, _gc_time_stamp);
2306 _failures = true;
2307 }
2308 return false;
2309 }
2310
2311 bool failures() { return _failures; }
2312 };
2313
2314 void G1CollectedHeap::check_gc_time_stamps() {
2315 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2316 heap_region_iterate(&cl);
2317 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2318 }
2319 #endif // PRODUCT
2320
2321 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2322 DirtyCardQueue* into_cset_dcq,
2323 bool concurrent,
2324 int worker_i) {
2325 // Clean cards in the hot card cache
2326 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2327 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2328
2329 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2330 int n_completed_buffers = 0;
2331 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2332 n_completed_buffers++;
2333 }
2334 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2335 dcqs.clear_n_completed_buffers();
2336 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2337 }
2338
2339
2340 // Computes the sum of the storage used by the various regions.
2341
2342 size_t G1CollectedHeap::used() const {
2343 assert(Heap_lock->owner() != NULL,
2344 "Should be owned on this thread's behalf.");
2345 size_t result = _summary_bytes_used;
2346 // Read only once in case it is set to NULL concurrently
2347 HeapRegion* hr = _mutator_alloc_region.get();
2348 if (hr != NULL)
2349 result += hr->used();
2350 return result;
2351 }
2352
2353 size_t G1CollectedHeap::used_unlocked() const {
2354 size_t result = _summary_bytes_used;
2355 return result;
2356 }
2357
2358 class SumUsedClosure: public HeapRegionClosure {
2359 size_t _used;
2360 public:
2361 SumUsedClosure() : _used(0) {}
2362 bool doHeapRegion(HeapRegion* r) {
2363 if (!r->continuesHumongous()) {
2364 _used += r->used();
2365 }
2366 return false;
2367 }
2368 size_t result() { return _used; }
2369 };
2370
2371 size_t G1CollectedHeap::recalculate_used() const {
2372 SumUsedClosure blk;
2373 heap_region_iterate(&blk);
2374 return blk.result();
2375 }
2376
2377 size_t G1CollectedHeap::unsafe_max_alloc() {
2378 if (free_regions() > 0) return HeapRegion::GrainBytes;
2379 // otherwise, is there space in the current allocation region?
2380
2381 // We need to store the current allocation region in a local variable
2382 // here. The problem is that this method doesn't take any locks and
2383 // there may be other threads which overwrite the current allocation
2384 // region field. attempt_allocation(), for example, sets it to NULL
2385 // and this can happen *after* the NULL check here but before the call
2386 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2387 // to be a problem in the optimized build, since the two loads of the
2388 // current allocation region field are optimized away.
2389 HeapRegion* hr = _mutator_alloc_region.get();
2390 if (hr == NULL) {
2391 return 0;
2392 }
2393 return hr->free();
2394 }
2395
2396 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2397 switch (cause) {
2398 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2399 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2400 case GCCause::_g1_humongous_allocation: return true;
2401 default: return false;
2402 }
2403 }
2404
2405 #ifndef PRODUCT
2406 void G1CollectedHeap::allocate_dummy_regions() {
2407 // Let's fill up most of the region
2408 size_t word_size = HeapRegion::GrainWords - 1024;
2409 // And as a result the region we'll allocate will be humongous.
2410 guarantee(isHumongous(word_size), "sanity");
2411
2412 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2413 // Let's use the existing mechanism for the allocation
2414 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2415 if (dummy_obj != NULL) {
2416 MemRegion mr(dummy_obj, word_size);
2417 CollectedHeap::fill_with_object(mr);
2418 } else {
2419 // If we can't allocate once, we probably cannot allocate
2420 // again. Let's get out of the loop.
2421 break;
2422 }
2423 }
2424 }
2425 #endif // !PRODUCT
2426
2427 void G1CollectedHeap::increment_old_marking_cycles_started() {
2428 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2429 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2430 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2431 _old_marking_cycles_started, _old_marking_cycles_completed));
2432
2433 _old_marking_cycles_started++;
2434 }
2435
2436 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2437 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2438
2439 // We assume that if concurrent == true, then the caller is a
2440 // concurrent thread that was joined the Suspendible Thread
2441 // Set. If there's ever a cheap way to check this, we should add an
2442 // assert here.
2443
2444 // Given that this method is called at the end of a Full GC or of a
2445 // concurrent cycle, and those can be nested (i.e., a Full GC can
2446 // interrupt a concurrent cycle), the number of full collections
2447 // completed should be either one (in the case where there was no
2448 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2449 // behind the number of full collections started.
2450
2451 // This is the case for the inner caller, i.e. a Full GC.
2452 assert(concurrent ||
2453 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2454 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2455 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2456 "is inconsistent with _old_marking_cycles_completed = %u",
2457 _old_marking_cycles_started, _old_marking_cycles_completed));
2458
2459 // This is the case for the outer caller, i.e. the concurrent cycle.
2460 assert(!concurrent ||
2461 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2462 err_msg("for outer caller (concurrent cycle): "
2463 "_old_marking_cycles_started = %u "
2464 "is inconsistent with _old_marking_cycles_completed = %u",
2465 _old_marking_cycles_started, _old_marking_cycles_completed));
2466
2467 _old_marking_cycles_completed += 1;
2468
2469 // We need to clear the "in_progress" flag in the CM thread before
2470 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2471 // is set) so that if a waiter requests another System.gc() it doesn't
2472 // incorrectly see that a marking cycle is still in progress.
2473 if (concurrent) {
2474 _cmThread->clear_in_progress();
2475 }
2476
2477 // This notify_all() will ensure that a thread that called
2478 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2479 // and it's waiting for a full GC to finish will be woken up. It is
2480 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2481 FullGCCount_lock->notify_all();
2482 }
2483
2484 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2485 _concurrent_cycle_started = true;
2486 _gc_timer_cm->register_gc_start(start_time);
2487
2488 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2489 trace_heap_before_gc(_gc_tracer_cm);
2490 }
2491
2492 void G1CollectedHeap::register_concurrent_cycle_end() {
2493 if (_concurrent_cycle_started) {
2494 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2495
2496 if (_cm->has_aborted()) {
2497 _gc_tracer_cm->report_concurrent_mode_failure();
2498 }
2499 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2500
2501 _concurrent_cycle_started = false;
2502 }
2503 }
2504
2505 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2506 if (_concurrent_cycle_started) {
2507 trace_heap_after_gc(_gc_tracer_cm);
2508 }
2509 }
2510
2511 G1YCType G1CollectedHeap::yc_type() {
2512 bool is_young = g1_policy()->gcs_are_young();
2513 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2514 bool is_during_mark = mark_in_progress();
2515
2516 if (is_initial_mark) {
2517 return InitialMark;
2518 } else if (is_during_mark) {
2519 return DuringMark;
2520 } else if (is_young) {
2521 return Normal;
2522 } else {
2523 return Mixed;
2524 }
2525 }
2526
2527 void G1CollectedHeap::collect(GCCause::Cause cause) {
2528 assert_heap_not_locked();
2529
2530 unsigned int gc_count_before;
2531 unsigned int old_marking_count_before;
2532 bool retry_gc;
2533
2534 do {
2535 retry_gc = false;
2536
2537 {
2538 MutexLocker ml(Heap_lock);
2539
2540 // Read the GC count while holding the Heap_lock
2541 gc_count_before = total_collections();
2542 old_marking_count_before = _old_marking_cycles_started;
2543 }
2544
2545 if (should_do_concurrent_full_gc(cause)) {
2546 // Schedule an initial-mark evacuation pause that will start a
2547 // concurrent cycle. We're setting word_size to 0 which means that
2548 // we are not requesting a post-GC allocation.
2549 VM_G1IncCollectionPause op(gc_count_before,
2550 0, /* word_size */
2551 true, /* should_initiate_conc_mark */
2552 g1_policy()->max_pause_time_ms(),
2553 cause);
2554
2555 VMThread::execute(&op);
2556 if (!op.pause_succeeded()) {
2557 if (old_marking_count_before == _old_marking_cycles_started) {
2558 retry_gc = op.should_retry_gc();
2559 } else {
2560 // A Full GC happened while we were trying to schedule the
2561 // initial-mark GC. No point in starting a new cycle given
2562 // that the whole heap was collected anyway.
2563 }
2564
2565 if (retry_gc) {
2566 if (GC_locker::is_active_and_needs_gc()) {
2567 GC_locker::stall_until_clear();
2568 }
2569 }
2570 }
2571 } else {
2572 if (cause == GCCause::_gc_locker
2573 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2574
2575 // Schedule a standard evacuation pause. We're setting word_size
2576 // to 0 which means that we are not requesting a post-GC allocation.
2577 VM_G1IncCollectionPause op(gc_count_before,
2578 0, /* word_size */
2579 false, /* should_initiate_conc_mark */
2580 g1_policy()->max_pause_time_ms(),
2581 cause);
2582 VMThread::execute(&op);
2583 } else {
2584 // Schedule a Full GC.
2585 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2586 VMThread::execute(&op);
2587 }
2588 }
2589 } while (retry_gc);
2590 }
2591
2592 bool G1CollectedHeap::is_in(const void* p) const {
2593 if (_g1_committed.contains(p)) {
2594 // Given that we know that p is in the committed space,
2595 // heap_region_containing_raw() should successfully
2596 // return the containing region.
2597 HeapRegion* hr = heap_region_containing_raw(p);
2598 return hr->is_in(p);
2599 } else {
2600 return false;
2601 }
2602 }
2603
2604 // Iteration functions.
2605
2606 // Iterates an OopClosure over all ref-containing fields of objects
2607 // within a HeapRegion.
2608
2609 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2610 MemRegion _mr;
2611 ExtendedOopClosure* _cl;
2612 public:
2613 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2614 : _mr(mr), _cl(cl) {}
2615 bool doHeapRegion(HeapRegion* r) {
2616 if (!r->continuesHumongous()) {
2617 r->oop_iterate(_cl);
2618 }
2619 return false;
2620 }
2621 };
2622
2623 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2624 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2625 heap_region_iterate(&blk);
2626 }
2627
2628 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2629 IterateOopClosureRegionClosure blk(mr, cl);
2630 heap_region_iterate(&blk);
2631 }
2632
2633 // Iterates an ObjectClosure over all objects within a HeapRegion.
2634
2635 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2636 ObjectClosure* _cl;
2637 public:
2638 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2639 bool doHeapRegion(HeapRegion* r) {
2640 if (! r->continuesHumongous()) {
2641 r->object_iterate(_cl);
2642 }
2643 return false;
2644 }
2645 };
2646
2647 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2648 IterateObjectClosureRegionClosure blk(cl);
2649 heap_region_iterate(&blk);
2650 }
2651
2652 // Calls a SpaceClosure on a HeapRegion.
2653
2654 class SpaceClosureRegionClosure: public HeapRegionClosure {
2655 SpaceClosure* _cl;
2656 public:
2657 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2658 bool doHeapRegion(HeapRegion* r) {
2659 _cl->do_space(r);
2660 return false;
2661 }
2662 };
2663
2664 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2665 SpaceClosureRegionClosure blk(cl);
2666 heap_region_iterate(&blk);
2667 }
2668
2669 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2670 _hrs.iterate(cl);
2671 }
2672
2673 void
2674 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2675 uint worker_id,
2676 uint no_of_par_workers,
2677 jint claim_value) {
2678 const uint regions = n_regions();
2679 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2680 no_of_par_workers :
2681 1);
2682 assert(UseDynamicNumberOfGCThreads ||
2683 no_of_par_workers == workers()->total_workers(),
2684 "Non dynamic should use fixed number of workers");
2685 // try to spread out the starting points of the workers
2686 const HeapRegion* start_hr =
2687 start_region_for_worker(worker_id, no_of_par_workers);
2688 const uint start_index = start_hr->hrs_index();
2689
2690 // each worker will actually look at all regions
2691 for (uint count = 0; count < regions; ++count) {
2692 const uint index = (start_index + count) % regions;
2693 assert(0 <= index && index < regions, "sanity");
2694 HeapRegion* r = region_at(index);
2695 // we'll ignore "continues humongous" regions (we'll process them
2696 // when we come across their corresponding "start humongous"
2697 // region) and regions already claimed
2698 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2699 continue;
2700 }
2701 // OK, try to claim it
2702 if (r->claimHeapRegion(claim_value)) {
2703 // success!
2704 assert(!r->continuesHumongous(), "sanity");
2705 if (r->startsHumongous()) {
2706 // If the region is "starts humongous" we'll iterate over its
2707 // "continues humongous" first; in fact we'll do them
2708 // first. The order is important. In on case, calling the
2709 // closure on the "starts humongous" region might de-allocate
2710 // and clear all its "continues humongous" regions and, as a
2711 // result, we might end up processing them twice. So, we'll do
2712 // them first (notice: most closures will ignore them anyway) and
2713 // then we'll do the "starts humongous" region.
2714 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2715 HeapRegion* chr = region_at(ch_index);
2716
2717 // if the region has already been claimed or it's not
2718 // "continues humongous" we're done
2719 if (chr->claim_value() == claim_value ||
2720 !chr->continuesHumongous()) {
2721 break;
2722 }
2723
2724 // No one should have claimed it directly. We can given
2725 // that we claimed its "starts humongous" region.
2726 assert(chr->claim_value() != claim_value, "sanity");
2727 assert(chr->humongous_start_region() == r, "sanity");
2728
2729 if (chr->claimHeapRegion(claim_value)) {
2730 // we should always be able to claim it; no one else should
2731 // be trying to claim this region
2732
2733 bool res2 = cl->doHeapRegion(chr);
2734 assert(!res2, "Should not abort");
2735
2736 // Right now, this holds (i.e., no closure that actually
2737 // does something with "continues humongous" regions
2738 // clears them). We might have to weaken it in the future,
2739 // but let's leave these two asserts here for extra safety.
2740 assert(chr->continuesHumongous(), "should still be the case");
2741 assert(chr->humongous_start_region() == r, "sanity");
2742 } else {
2743 guarantee(false, "we should not reach here");
2744 }
2745 }
2746 }
2747
2748 assert(!r->continuesHumongous(), "sanity");
2749 bool res = cl->doHeapRegion(r);
2750 assert(!res, "Should not abort");
2751 }
2752 }
2753 }
2754
2755 class ResetClaimValuesClosure: public HeapRegionClosure {
2756 public:
2757 bool doHeapRegion(HeapRegion* r) {
2758 r->set_claim_value(HeapRegion::InitialClaimValue);
2759 return false;
2760 }
2761 };
2762
2763 void G1CollectedHeap::reset_heap_region_claim_values() {
2764 ResetClaimValuesClosure blk;
2765 heap_region_iterate(&blk);
2766 }
2767
2768 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2769 ResetClaimValuesClosure blk;
2770 collection_set_iterate(&blk);
2771 }
2772
2773 #ifdef ASSERT
2774 // This checks whether all regions in the heap have the correct claim
2775 // value. I also piggy-backed on this a check to ensure that the
2776 // humongous_start_region() information on "continues humongous"
2777 // regions is correct.
2778
2779 class CheckClaimValuesClosure : public HeapRegionClosure {
2780 private:
2781 jint _claim_value;
2782 uint _failures;
2783 HeapRegion* _sh_region;
2784
2785 public:
2786 CheckClaimValuesClosure(jint claim_value) :
2787 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2788 bool doHeapRegion(HeapRegion* r) {
2789 if (r->claim_value() != _claim_value) {
2790 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2791 "claim value = %d, should be %d",
2792 HR_FORMAT_PARAMS(r),
2793 r->claim_value(), _claim_value);
2794 ++_failures;
2795 }
2796 if (!r->isHumongous()) {
2797 _sh_region = NULL;
2798 } else if (r->startsHumongous()) {
2799 _sh_region = r;
2800 } else if (r->continuesHumongous()) {
2801 if (r->humongous_start_region() != _sh_region) {
2802 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2803 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2804 HR_FORMAT_PARAMS(r),
2805 r->humongous_start_region(),
2806 _sh_region);
2807 ++_failures;
2808 }
2809 }
2810 return false;
2811 }
2812 uint failures() { return _failures; }
2813 };
2814
2815 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2816 CheckClaimValuesClosure cl(claim_value);
2817 heap_region_iterate(&cl);
2818 return cl.failures() == 0;
2819 }
2820
2821 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2822 private:
2823 jint _claim_value;
2824 uint _failures;
2825
2826 public:
2827 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2828 _claim_value(claim_value), _failures(0) { }
2829
2830 uint failures() { return _failures; }
2831
2832 bool doHeapRegion(HeapRegion* hr) {
2833 assert(hr->in_collection_set(), "how?");
2834 assert(!hr->isHumongous(), "H-region in CSet");
2835 if (hr->claim_value() != _claim_value) {
2836 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2837 "claim value = %d, should be %d",
2838 HR_FORMAT_PARAMS(hr),
2839 hr->claim_value(), _claim_value);
2840 _failures += 1;
2841 }
2842 return false;
2843 }
2844 };
2845
2846 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2847 CheckClaimValuesInCSetHRClosure cl(claim_value);
2848 collection_set_iterate(&cl);
2849 return cl.failures() == 0;
2850 }
2851 #endif // ASSERT
2852
2853 // Clear the cached CSet starting regions and (more importantly)
2854 // the time stamps. Called when we reset the GC time stamp.
2855 void G1CollectedHeap::clear_cset_start_regions() {
2856 assert(_worker_cset_start_region != NULL, "sanity");
2857 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2858
2859 int n_queues = MAX2((int)ParallelGCThreads, 1);
2860 for (int i = 0; i < n_queues; i++) {
2861 _worker_cset_start_region[i] = NULL;
2862 _worker_cset_start_region_time_stamp[i] = 0;
2863 }
2864 }
2865
2866 // Given the id of a worker, obtain or calculate a suitable
2867 // starting region for iterating over the current collection set.
2868 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2869 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2870
2871 HeapRegion* result = NULL;
2872 unsigned gc_time_stamp = get_gc_time_stamp();
2873
2874 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2875 // Cached starting region for current worker was set
2876 // during the current pause - so it's valid.
2877 // Note: the cached starting heap region may be NULL
2878 // (when the collection set is empty).
2879 result = _worker_cset_start_region[worker_i];
2880 assert(result == NULL || result->in_collection_set(), "sanity");
2881 return result;
2882 }
2883
2884 // The cached entry was not valid so let's calculate
2885 // a suitable starting heap region for this worker.
2886
2887 // We want the parallel threads to start their collection
2888 // set iteration at different collection set regions to
2889 // avoid contention.
2890 // If we have:
2891 // n collection set regions
2892 // p threads
2893 // Then thread t will start at region floor ((t * n) / p)
2894
2895 result = g1_policy()->collection_set();
2896 if (G1CollectedHeap::use_parallel_gc_threads()) {
2897 uint cs_size = g1_policy()->cset_region_length();
2898 uint active_workers = workers()->active_workers();
2899 assert(UseDynamicNumberOfGCThreads ||
2900 active_workers == workers()->total_workers(),
2901 "Unless dynamic should use total workers");
2902
2903 uint end_ind = (cs_size * worker_i) / active_workers;
2904 uint start_ind = 0;
2905
2906 if (worker_i > 0 &&
2907 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2908 // Previous workers starting region is valid
2909 // so let's iterate from there
2910 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2911 result = _worker_cset_start_region[worker_i - 1];
2912 }
2913
2914 for (uint i = start_ind; i < end_ind; i++) {
2915 result = result->next_in_collection_set();
2916 }
2917 }
2918
2919 // Note: the calculated starting heap region may be NULL
2920 // (when the collection set is empty).
2921 assert(result == NULL || result->in_collection_set(), "sanity");
2922 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2923 "should be updated only once per pause");
2924 _worker_cset_start_region[worker_i] = result;
2925 OrderAccess::storestore();
2926 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2927 return result;
2928 }
2929
2930 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2931 uint no_of_par_workers) {
2932 uint worker_num =
2933 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2934 assert(UseDynamicNumberOfGCThreads ||
2935 no_of_par_workers == workers()->total_workers(),
2936 "Non dynamic should use fixed number of workers");
2937 const uint start_index = n_regions() * worker_i / worker_num;
2938 return region_at(start_index);
2939 }
2940
2941 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2942 HeapRegion* r = g1_policy()->collection_set();
2943 while (r != NULL) {
2944 HeapRegion* next = r->next_in_collection_set();
2945 if (cl->doHeapRegion(r)) {
2946 cl->incomplete();
2947 return;
2948 }
2949 r = next;
2950 }
2951 }
2952
2953 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2954 HeapRegionClosure *cl) {
2955 if (r == NULL) {
2956 // The CSet is empty so there's nothing to do.
2957 return;
2958 }
2959
2960 assert(r->in_collection_set(),
2961 "Start region must be a member of the collection set.");
2962 HeapRegion* cur = r;
2963 while (cur != NULL) {
2964 HeapRegion* next = cur->next_in_collection_set();
2965 if (cl->doHeapRegion(cur) && false) {
2966 cl->incomplete();
2967 return;
2968 }
2969 cur = next;
2970 }
2971 cur = g1_policy()->collection_set();
2972 while (cur != r) {
2973 HeapRegion* next = cur->next_in_collection_set();
2974 if (cl->doHeapRegion(cur) && false) {
2975 cl->incomplete();
2976 return;
2977 }
2978 cur = next;
2979 }
2980 }
2981
2982 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2983 return n_regions() > 0 ? region_at(0) : NULL;
2984 }
2985
2986
2987 Space* G1CollectedHeap::space_containing(const void* addr) const {
2988 Space* res = heap_region_containing(addr);
2989 return res;
2990 }
2991
2992 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2993 Space* sp = space_containing(addr);
2994 if (sp != NULL) {
2995 return sp->block_start(addr);
2996 }
2997 return NULL;
2998 }
2999
3000 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3001 Space* sp = space_containing(addr);
3002 assert(sp != NULL, "block_size of address outside of heap");
3003 return sp->block_size(addr);
3004 }
3005
3006 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3007 Space* sp = space_containing(addr);
3008 return sp->block_is_obj(addr);
3009 }
3010
3011 bool G1CollectedHeap::supports_tlab_allocation() const {
3012 return true;
3013 }
3014
3015 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3016 return HeapRegion::GrainBytes;
3017 }
3018
3019 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3020 // Return the remaining space in the cur alloc region, but not less than
3021 // the min TLAB size.
3022
3023 // Also, this value can be at most the humongous object threshold,
3024 // since we can't allow tlabs to grow big enough to accommodate
3025 // humongous objects.
3026
3027 HeapRegion* hr = _mutator_alloc_region.get();
3028 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3029 if (hr == NULL) {
3030 return max_tlab_size;
3031 } else {
3032 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3033 }
3034 }
3035
3036 size_t G1CollectedHeap::max_capacity() const {
3037 return _g1_reserved.byte_size();
3038 }
3039
3040 jlong G1CollectedHeap::millis_since_last_gc() {
3041 // assert(false, "NYI");
3042 return 0;
3043 }
3044
3045 void G1CollectedHeap::prepare_for_verify() {
3046 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3047 ensure_parsability(false);
3048 }
3049 g1_rem_set()->prepare_for_verify();
3050 }
3051
3052 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3053 VerifyOption vo) {
3054 switch (vo) {
3055 case VerifyOption_G1UsePrevMarking:
3056 return hr->obj_allocated_since_prev_marking(obj);
3057 case VerifyOption_G1UseNextMarking:
3058 return hr->obj_allocated_since_next_marking(obj);
3059 case VerifyOption_G1UseMarkWord:
3060 return false;
3061 default:
3062 ShouldNotReachHere();
3063 }
3064 return false; // keep some compilers happy
3065 }
3066
3067 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3068 switch (vo) {
3069 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3070 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3071 case VerifyOption_G1UseMarkWord: return NULL;
3072 default: ShouldNotReachHere();
3073 }
3074 return NULL; // keep some compilers happy
3075 }
3076
3077 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3078 switch (vo) {
3079 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3080 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3081 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3082 default: ShouldNotReachHere();
3083 }
3084 return false; // keep some compilers happy
3085 }
3086
3087 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3088 switch (vo) {
3089 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3090 case VerifyOption_G1UseNextMarking: return "NTAMS";
3091 case VerifyOption_G1UseMarkWord: return "NONE";
3092 default: ShouldNotReachHere();
3093 }
3094 return NULL; // keep some compilers happy
3095 }
3096
3097 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3098 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3099 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3100 // we can change this closure to extend the simpler OopClosure.
3101 class VerifyRootsClosure: public OopsInGenClosure {
3102 private:
3103 G1CollectedHeap* _g1h;
3104 VerifyOption _vo;
3105 bool _failures;
3106 public:
3107 // _vo == UsePrevMarking -> use "prev" marking information,
3108 // _vo == UseNextMarking -> use "next" marking information,
3109 // _vo == UseMarkWord -> use mark word from object header.
3110 VerifyRootsClosure(VerifyOption vo) :
3111 _g1h(G1CollectedHeap::heap()),
3112 _vo(vo),
3113 _failures(false) { }
3114
3115 bool failures() { return _failures; }
3116
3117 template <class T> void do_oop_nv(T* p) {
3118 T heap_oop = oopDesc::load_heap_oop(p);
3119 if (!oopDesc::is_null(heap_oop)) {
3120 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3121 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3122 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3123 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3124 if (_vo == VerifyOption_G1UseMarkWord) {
3125 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3126 }
3127 obj->print_on(gclog_or_tty);
3128 _failures = true;
3129 }
3130 }
3131 }
3132
3133 void do_oop(oop* p) { do_oop_nv(p); }
3134 void do_oop(narrowOop* p) { do_oop_nv(p); }
3135 };
3136
3137 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3138 G1CollectedHeap* _g1h;
3139 OopClosure* _root_cl;
3140 nmethod* _nm;
3141 VerifyOption _vo;
3142 bool _failures;
3143
3144 template <class T> void do_oop_work(T* p) {
3145 // First verify that this root is live
3146 _root_cl->do_oop(p);
3147
3148 if (!G1VerifyHeapRegionCodeRoots) {
3149 // We're not verifying the code roots attached to heap region.
3150 return;
3151 }
3152
3153 // Don't check the code roots during marking verification in a full GC
3154 if (_vo == VerifyOption_G1UseMarkWord) {
3155 return;
3156 }
3157
3158 // Now verify that the current nmethod (which contains p) is
3159 // in the code root list of the heap region containing the
3160 // object referenced by p.
3161
3162 T heap_oop = oopDesc::load_heap_oop(p);
3163 if (!oopDesc::is_null(heap_oop)) {
3164 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3165
3166 // Now fetch the region containing the object
3167 HeapRegion* hr = _g1h->heap_region_containing(obj);
3168 HeapRegionRemSet* hrrs = hr->rem_set();
3169 // Verify that the strong code root list for this region
3170 // contains the nmethod
3171 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3172 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3173 "from nmethod "PTR_FORMAT" not in strong "
3174 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3175 p, _nm, hr->bottom(), hr->end());
3176 _failures = true;
3177 }
3178 }
3179 }
3180
3181 public:
3182 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3183 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3184
3185 void do_oop(oop* p) { do_oop_work(p); }
3186 void do_oop(narrowOop* p) { do_oop_work(p); }
3187
3188 void set_nmethod(nmethod* nm) { _nm = nm; }
3189 bool failures() { return _failures; }
3190 };
3191
3192 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3193 G1VerifyCodeRootOopClosure* _oop_cl;
3194
3195 public:
3196 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3197 _oop_cl(oop_cl) {}
3198
3199 void do_code_blob(CodeBlob* cb) {
3200 nmethod* nm = cb->as_nmethod_or_null();
3201 if (nm != NULL) {
3202 _oop_cl->set_nmethod(nm);
3203 nm->oops_do(_oop_cl);
3204 }
3205 }
3206 };
3207
3208 class YoungRefCounterClosure : public OopClosure {
3209 G1CollectedHeap* _g1h;
3210 int _count;
3211 public:
3212 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3213 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3214 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3215
3216 int count() { return _count; }
3217 void reset_count() { _count = 0; };
3218 };
3219
3220 class VerifyKlassClosure: public KlassClosure {
3221 YoungRefCounterClosure _young_ref_counter_closure;
3222 OopClosure *_oop_closure;
3223 public:
3224 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3225 void do_klass(Klass* k) {
3226 k->oops_do(_oop_closure);
3227
3228 _young_ref_counter_closure.reset_count();
3229 k->oops_do(&_young_ref_counter_closure);
3230 if (_young_ref_counter_closure.count() > 0) {
3231 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3232 }
3233 }
3234 };
3235
3236 class VerifyLivenessOopClosure: public OopClosure {
3237 G1CollectedHeap* _g1h;
3238 VerifyOption _vo;
3239 public:
3240 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3241 _g1h(g1h), _vo(vo)
3242 { }
3243 void do_oop(narrowOop *p) { do_oop_work(p); }
3244 void do_oop( oop *p) { do_oop_work(p); }
3245
3246 template <class T> void do_oop_work(T *p) {
3247 oop obj = oopDesc::load_decode_heap_oop(p);
3248 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3249 "Dead object referenced by a not dead object");
3250 }
3251 };
3252
3253 class VerifyObjsInRegionClosure: public ObjectClosure {
3254 private:
3255 G1CollectedHeap* _g1h;
3256 size_t _live_bytes;
3257 HeapRegion *_hr;
3258 VerifyOption _vo;
3259 public:
3260 // _vo == UsePrevMarking -> use "prev" marking information,
3261 // _vo == UseNextMarking -> use "next" marking information,
3262 // _vo == UseMarkWord -> use mark word from object header.
3263 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3264 : _live_bytes(0), _hr(hr), _vo(vo) {
3265 _g1h = G1CollectedHeap::heap();
3266 }
3267 void do_object(oop o) {
3268 VerifyLivenessOopClosure isLive(_g1h, _vo);
3269 assert(o != NULL, "Huh?");
3270 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3271 // If the object is alive according to the mark word,
3272 // then verify that the marking information agrees.
3273 // Note we can't verify the contra-positive of the
3274 // above: if the object is dead (according to the mark
3275 // word), it may not be marked, or may have been marked
3276 // but has since became dead, or may have been allocated
3277 // since the last marking.
3278 if (_vo == VerifyOption_G1UseMarkWord) {
3279 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3280 }
3281
3282 o->oop_iterate_no_header(&isLive);
3283 if (!_hr->obj_allocated_since_prev_marking(o)) {
3284 size_t obj_size = o->size(); // Make sure we don't overflow
3285 _live_bytes += (obj_size * HeapWordSize);
3286 }
3287 }
3288 }
3289 size_t live_bytes() { return _live_bytes; }
3290 };
3291
3292 class PrintObjsInRegionClosure : public ObjectClosure {
3293 HeapRegion *_hr;
3294 G1CollectedHeap *_g1;
3295 public:
3296 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3297 _g1 = G1CollectedHeap::heap();
3298 };
3299
3300 void do_object(oop o) {
3301 if (o != NULL) {
3302 HeapWord *start = (HeapWord *) o;
3303 size_t word_sz = o->size();
3304 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3305 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3306 (void*) o, word_sz,
3307 _g1->isMarkedPrev(o),
3308 _g1->isMarkedNext(o),
3309 _hr->obj_allocated_since_prev_marking(o));
3310 HeapWord *end = start + word_sz;
3311 HeapWord *cur;
3312 int *val;
3313 for (cur = start; cur < end; cur++) {
3314 val = (int *) cur;
3315 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3316 }
3317 }
3318 }
3319 };
3320
3321 class VerifyRegionClosure: public HeapRegionClosure {
3322 private:
3323 bool _par;
3324 VerifyOption _vo;
3325 bool _failures;
3326 public:
3327 // _vo == UsePrevMarking -> use "prev" marking information,
3328 // _vo == UseNextMarking -> use "next" marking information,
3329 // _vo == UseMarkWord -> use mark word from object header.
3330 VerifyRegionClosure(bool par, VerifyOption vo)
3331 : _par(par),
3332 _vo(vo),
3333 _failures(false) {}
3334
3335 bool failures() {
3336 return _failures;
3337 }
3338
3339 bool doHeapRegion(HeapRegion* r) {
3340 if (!r->continuesHumongous()) {
3341 bool failures = false;
3342 r->verify(_vo, &failures);
3343 if (failures) {
3344 _failures = true;
3345 } else {
3346 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3347 r->object_iterate(¬_dead_yet_cl);
3348 if (_vo != VerifyOption_G1UseNextMarking) {
3349 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3350 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3351 "max_live_bytes "SIZE_FORMAT" "
3352 "< calculated "SIZE_FORMAT,
3353 r->bottom(), r->end(),
3354 r->max_live_bytes(),
3355 not_dead_yet_cl.live_bytes());
3356 _failures = true;
3357 }
3358 } else {
3359 // When vo == UseNextMarking we cannot currently do a sanity
3360 // check on the live bytes as the calculation has not been
3361 // finalized yet.
3362 }
3363 }
3364 }
3365 return false; // stop the region iteration if we hit a failure
3366 }
3367 };
3368
3369 // This is the task used for parallel verification of the heap regions
3370
3371 class G1ParVerifyTask: public AbstractGangTask {
3372 private:
3373 G1CollectedHeap* _g1h;
3374 VerifyOption _vo;
3375 bool _failures;
3376
3377 public:
3378 // _vo == UsePrevMarking -> use "prev" marking information,
3379 // _vo == UseNextMarking -> use "next" marking information,
3380 // _vo == UseMarkWord -> use mark word from object header.
3381 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3382 AbstractGangTask("Parallel verify task"),
3383 _g1h(g1h),
3384 _vo(vo),
3385 _failures(false) { }
3386
3387 bool failures() {
3388 return _failures;
3389 }
3390
3391 void work(uint worker_id) {
3392 HandleMark hm;
3393 VerifyRegionClosure blk(true, _vo);
3394 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3395 _g1h->workers()->active_workers(),
3396 HeapRegion::ParVerifyClaimValue);
3397 if (blk.failures()) {
3398 _failures = true;
3399 }
3400 }
3401 };
3402
3403 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3404 if (SafepointSynchronize::is_at_safepoint()) {
3405 assert(Thread::current()->is_VM_thread(),
3406 "Expected to be executed serially by the VM thread at this point");
3407
3408 if (!silent) { gclog_or_tty->print("Roots "); }
3409 VerifyRootsClosure rootsCl(vo);
3410 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3411 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3412 VerifyKlassClosure klassCl(this, &rootsCl);
3413
3414 // We apply the relevant closures to all the oops in the
3415 // system dictionary, the string table and the code cache.
3416 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3417
3418 // Need cleared claim bits for the strong roots processing
3419 ClassLoaderDataGraph::clear_claimed_marks();
3420
3421 process_strong_roots(true, // activate StrongRootsScope
3422 false, // we set "is scavenging" to false,
3423 // so we don't reset the dirty cards.
3424 ScanningOption(so), // roots scanning options
3425 &rootsCl,
3426 &blobsCl,
3427 &klassCl
3428 );
3429
3430 bool failures = rootsCl.failures() || codeRootsCl.failures();
3431
3432 if (vo != VerifyOption_G1UseMarkWord) {
3433 // If we're verifying during a full GC then the region sets
3434 // will have been torn down at the start of the GC. Therefore
3435 // verifying the region sets will fail. So we only verify
3436 // the region sets when not in a full GC.
3437 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3438 verify_region_sets();
3439 }
3440
3441 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3442 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3443 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3444 "sanity check");
3445
3446 G1ParVerifyTask task(this, vo);
3447 assert(UseDynamicNumberOfGCThreads ||
3448 workers()->active_workers() == workers()->total_workers(),
3449 "If not dynamic should be using all the workers");
3450 int n_workers = workers()->active_workers();
3451 set_par_threads(n_workers);
3452 workers()->run_task(&task);
3453 set_par_threads(0);
3454 if (task.failures()) {
3455 failures = true;
3456 }
3457
3458 // Checks that the expected amount of parallel work was done.
3459 // The implication is that n_workers is > 0.
3460 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3461 "sanity check");
3462
3463 reset_heap_region_claim_values();
3464
3465 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3466 "sanity check");
3467 } else {
3468 VerifyRegionClosure blk(false, vo);
3469 heap_region_iterate(&blk);
3470 if (blk.failures()) {
3471 failures = true;
3472 }
3473 }
3474 if (!silent) gclog_or_tty->print("RemSet ");
3475 rem_set()->verify();
3476
3477 if (failures) {
3478 gclog_or_tty->print_cr("Heap:");
3479 // It helps to have the per-region information in the output to
3480 // help us track down what went wrong. This is why we call
3481 // print_extended_on() instead of print_on().
3482 print_extended_on(gclog_or_tty);
3483 gclog_or_tty->print_cr("");
3484 #ifndef PRODUCT
3485 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3486 concurrent_mark()->print_reachable("at-verification-failure",
3487 vo, false /* all */);
3488 }
3489 #endif
3490 gclog_or_tty->flush();
3491 }
3492 guarantee(!failures, "there should not have been any failures");
3493 } else {
3494 if (!silent)
3495 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3496 }
3497 }
3498
3499 void G1CollectedHeap::verify(bool silent) {
3500 verify(silent, VerifyOption_G1UsePrevMarking);
3501 }
3502
3503 double G1CollectedHeap::verify(bool guard, const char* msg) {
3504 double verify_time_ms = 0.0;
3505
3506 if (guard && total_collections() >= VerifyGCStartAt) {
3507 double verify_start = os::elapsedTime();
3508 HandleMark hm; // Discard invalid handles created during verification
3509 prepare_for_verify();
3510 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3511 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3512 }
3513
3514 return verify_time_ms;
3515 }
3516
3517 void G1CollectedHeap::verify_before_gc() {
3518 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3519 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3520 }
3521
3522 void G1CollectedHeap::verify_after_gc() {
3523 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3524 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3525 }
3526
3527 class PrintRegionClosure: public HeapRegionClosure {
3528 outputStream* _st;
3529 public:
3530 PrintRegionClosure(outputStream* st) : _st(st) {}
3531 bool doHeapRegion(HeapRegion* r) {
3532 r->print_on(_st);
3533 return false;
3534 }
3535 };
3536
3537 void G1CollectedHeap::print_on(outputStream* st) const {
3538 st->print(" %-20s", "garbage-first heap");
3539 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3540 capacity()/K, used_unlocked()/K);
3541 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3542 _g1_storage.low_boundary(),
3543 _g1_storage.high(),
3544 _g1_storage.high_boundary());
3545 st->cr();
3546 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3547 uint young_regions = _young_list->length();
3548 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3549 (size_t) young_regions * HeapRegion::GrainBytes / K);
3550 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3551 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3552 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3553 st->cr();
3554 MetaspaceAux::print_on(st);
3555 }
3556
3557 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3558 print_on(st);
3559
3560 // Print the per-region information.
3561 st->cr();
3562 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3563 "HS=humongous(starts), HC=humongous(continues), "
3564 "CS=collection set, F=free, TS=gc time stamp, "
3565 "PTAMS=previous top-at-mark-start, "
3566 "NTAMS=next top-at-mark-start)");
3567 PrintRegionClosure blk(st);
3568 heap_region_iterate(&blk);
3569 }
3570
3571 void G1CollectedHeap::print_on_error(outputStream* st) const {
3572 this->CollectedHeap::print_on_error(st);
3573
3574 if (_cm != NULL) {
3575 st->cr();
3576 _cm->print_on_error(st);
3577 }
3578 }
3579
3580 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3581 if (G1CollectedHeap::use_parallel_gc_threads()) {
3582 workers()->print_worker_threads_on(st);
3583 }
3584 _cmThread->print_on(st);
3585 st->cr();
3586 _cm->print_worker_threads_on(st);
3587 _cg1r->print_worker_threads_on(st);
3588 }
3589
3590 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3591 if (G1CollectedHeap::use_parallel_gc_threads()) {
3592 workers()->threads_do(tc);
3593 }
3594 tc->do_thread(_cmThread);
3595 _cg1r->threads_do(tc);
3596 }
3597
3598 void G1CollectedHeap::print_tracing_info() const {
3599 // We'll overload this to mean "trace GC pause statistics."
3600 if (TraceGen0Time || TraceGen1Time) {
3601 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3602 // to that.
3603 g1_policy()->print_tracing_info();
3604 }
3605 if (G1SummarizeRSetStats) {
3606 g1_rem_set()->print_summary_info();
3607 }
3608 if (G1SummarizeConcMark) {
3609 concurrent_mark()->print_summary_info();
3610 }
3611 g1_policy()->print_yg_surv_rate_info();
3612 SpecializationStats::print();
3613 }
3614
3615 #ifndef PRODUCT
3616 // Helpful for debugging RSet issues.
3617
3618 class PrintRSetsClosure : public HeapRegionClosure {
3619 private:
3620 const char* _msg;
3621 size_t _occupied_sum;
3622
3623 public:
3624 bool doHeapRegion(HeapRegion* r) {
3625 HeapRegionRemSet* hrrs = r->rem_set();
3626 size_t occupied = hrrs->occupied();
3627 _occupied_sum += occupied;
3628
3629 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3630 HR_FORMAT_PARAMS(r));
3631 if (occupied == 0) {
3632 gclog_or_tty->print_cr(" RSet is empty");
3633 } else {
3634 hrrs->print();
3635 }
3636 gclog_or_tty->print_cr("----------");
3637 return false;
3638 }
3639
3640 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3641 gclog_or_tty->cr();
3642 gclog_or_tty->print_cr("========================================");
3643 gclog_or_tty->print_cr(msg);
3644 gclog_or_tty->cr();
3645 }
3646
3647 ~PrintRSetsClosure() {
3648 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3649 gclog_or_tty->print_cr("========================================");
3650 gclog_or_tty->cr();
3651 }
3652 };
3653
3654 void G1CollectedHeap::print_cset_rsets() {
3655 PrintRSetsClosure cl("Printing CSet RSets");
3656 collection_set_iterate(&cl);
3657 }
3658
3659 void G1CollectedHeap::print_all_rsets() {
3660 PrintRSetsClosure cl("Printing All RSets");;
3661 heap_region_iterate(&cl);
3662 }
3663 #endif // PRODUCT
3664
3665 G1CollectedHeap* G1CollectedHeap::heap() {
3666 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3667 "not a garbage-first heap");
3668 return _g1h;
3669 }
3670
3671 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3672 // always_do_update_barrier = false;
3673 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3674 // Fill TLAB's and such
3675 ensure_parsability(true);
3676 }
3677
3678 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3679
3680 if (G1SummarizeRSetStats &&
3681 (G1SummarizeRSetStatsPeriod > 0) &&
3682 // we are at the end of the GC. Total collections has already been increased.
3683 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3684 g1_rem_set()->print_periodic_summary_info();
3685 }
3686
3687 // FIXME: what is this about?
3688 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3689 // is set.
3690 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3691 "derived pointer present"));
3692 // always_do_update_barrier = true;
3693
3694 // We have just completed a GC. Update the soft reference
3695 // policy with the new heap occupancy
3696 Universe::update_heap_info_at_gc();
3697 }
3698
3699 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3700 unsigned int gc_count_before,
3701 bool* succeeded) {
3702 assert_heap_not_locked_and_not_at_safepoint();
3703 g1_policy()->record_stop_world_start();
3704 VM_G1IncCollectionPause op(gc_count_before,
3705 word_size,
3706 false, /* should_initiate_conc_mark */
3707 g1_policy()->max_pause_time_ms(),
3708 GCCause::_g1_inc_collection_pause);
3709 VMThread::execute(&op);
3710
3711 HeapWord* result = op.result();
3712 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3713 assert(result == NULL || ret_succeeded,
3714 "the result should be NULL if the VM did not succeed");
3715 *succeeded = ret_succeeded;
3716
3717 assert_heap_not_locked();
3718 return result;
3719 }
3720
3721 void
3722 G1CollectedHeap::doConcurrentMark() {
3723 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3724 if (!_cmThread->in_progress()) {
3725 _cmThread->set_started();
3726 CGC_lock->notify();
3727 }
3728 }
3729
3730 size_t G1CollectedHeap::pending_card_num() {
3731 size_t extra_cards = 0;
3732 JavaThread *curr = Threads::first();
3733 while (curr != NULL) {
3734 DirtyCardQueue& dcq = curr->dirty_card_queue();
3735 extra_cards += dcq.size();
3736 curr = curr->next();
3737 }
3738 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3739 size_t buffer_size = dcqs.buffer_size();
3740 size_t buffer_num = dcqs.completed_buffers_num();
3741
3742 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3743 // in bytes - not the number of 'entries'. We need to convert
3744 // into a number of cards.
3745 return (buffer_size * buffer_num + extra_cards) / oopSize;
3746 }
3747
3748 size_t G1CollectedHeap::cards_scanned() {
3749 return g1_rem_set()->cardsScanned();
3750 }
3751
3752 void
3753 G1CollectedHeap::setup_surviving_young_words() {
3754 assert(_surviving_young_words == NULL, "pre-condition");
3755 uint array_length = g1_policy()->young_cset_region_length();
3756 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3757 if (_surviving_young_words == NULL) {
3758 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3759 "Not enough space for young surv words summary.");
3760 }
3761 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3762 #ifdef ASSERT
3763 for (uint i = 0; i < array_length; ++i) {
3764 assert( _surviving_young_words[i] == 0, "memset above" );
3765 }
3766 #endif // !ASSERT
3767 }
3768
3769 void
3770 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3771 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3772 uint array_length = g1_policy()->young_cset_region_length();
3773 for (uint i = 0; i < array_length; ++i) {
3774 _surviving_young_words[i] += surv_young_words[i];
3775 }
3776 }
3777
3778 void
3779 G1CollectedHeap::cleanup_surviving_young_words() {
3780 guarantee( _surviving_young_words != NULL, "pre-condition" );
3781 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3782 _surviving_young_words = NULL;
3783 }
3784
3785 #ifdef ASSERT
3786 class VerifyCSetClosure: public HeapRegionClosure {
3787 public:
3788 bool doHeapRegion(HeapRegion* hr) {
3789 // Here we check that the CSet region's RSet is ready for parallel
3790 // iteration. The fields that we'll verify are only manipulated
3791 // when the region is part of a CSet and is collected. Afterwards,
3792 // we reset these fields when we clear the region's RSet (when the
3793 // region is freed) so they are ready when the region is
3794 // re-allocated. The only exception to this is if there's an
3795 // evacuation failure and instead of freeing the region we leave
3796 // it in the heap. In that case, we reset these fields during
3797 // evacuation failure handling.
3798 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3799
3800 // Here's a good place to add any other checks we'd like to
3801 // perform on CSet regions.
3802 return false;
3803 }
3804 };
3805 #endif // ASSERT
3806
3807 #if TASKQUEUE_STATS
3808 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3809 st->print_raw_cr("GC Task Stats");
3810 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3811 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3812 }
3813
3814 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3815 print_taskqueue_stats_hdr(st);
3816
3817 TaskQueueStats totals;
3818 const int n = workers() != NULL ? workers()->total_workers() : 1;
3819 for (int i = 0; i < n; ++i) {
3820 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3821 totals += task_queue(i)->stats;
3822 }
3823 st->print_raw("tot "); totals.print(st); st->cr();
3824
3825 DEBUG_ONLY(totals.verify());
3826 }
3827
3828 void G1CollectedHeap::reset_taskqueue_stats() {
3829 const int n = workers() != NULL ? workers()->total_workers() : 1;
3830 for (int i = 0; i < n; ++i) {
3831 task_queue(i)->stats.reset();
3832 }
3833 }
3834 #endif // TASKQUEUE_STATS
3835
3836 void G1CollectedHeap::log_gc_header() {
3837 if (!G1Log::fine()) {
3838 return;
3839 }
3840
3841 gclog_or_tty->date_stamp(PrintGCDateStamps);
3842 gclog_or_tty->stamp(PrintGCTimeStamps);
3843
3844 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3845 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3846 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3847
3848 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3849 }
3850
3851 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3852 if (!G1Log::fine()) {
3853 return;
3854 }
3855
3856 if (G1Log::finer()) {
3857 if (evacuation_failed()) {
3858 gclog_or_tty->print(" (to-space exhausted)");
3859 }
3860 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3861 g1_policy()->phase_times()->note_gc_end();
3862 g1_policy()->phase_times()->print(pause_time_sec);
3863 g1_policy()->print_detailed_heap_transition();
3864 } else {
3865 if (evacuation_failed()) {
3866 gclog_or_tty->print("--");
3867 }
3868 g1_policy()->print_heap_transition();
3869 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3870 }
3871 gclog_or_tty->flush();
3872 }
3873
3874 bool
3875 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3876 assert_at_safepoint(true /* should_be_vm_thread */);
3877 guarantee(!is_gc_active(), "collection is not reentrant");
3878
3879 if (GC_locker::check_active_before_gc()) {
3880 return false;
3881 }
3882
3883 _gc_timer_stw->register_gc_start(os::elapsed_counter());
3884
3885 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3886
3887 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3888 ResourceMark rm;
3889
3890 print_heap_before_gc();
3891 trace_heap_before_gc(_gc_tracer_stw);
3892
3893 HRSPhaseSetter x(HRSPhaseEvacuation);
3894 verify_region_sets_optional();
3895 verify_dirty_young_regions();
3896
3897 // This call will decide whether this pause is an initial-mark
3898 // pause. If it is, during_initial_mark_pause() will return true
3899 // for the duration of this pause.
3900 g1_policy()->decide_on_conc_mark_initiation();
3901
3902 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3903 assert(!g1_policy()->during_initial_mark_pause() ||
3904 g1_policy()->gcs_are_young(), "sanity");
3905
3906 // We also do not allow mixed GCs during marking.
3907 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3908
3909 // Record whether this pause is an initial mark. When the current
3910 // thread has completed its logging output and it's safe to signal
3911 // the CM thread, the flag's value in the policy has been reset.
3912 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3913
3914 // Inner scope for scope based logging, timers, and stats collection
3915 {
3916 EvacuationInfo evacuation_info;
3917
3918 if (g1_policy()->during_initial_mark_pause()) {
3919 // We are about to start a marking cycle, so we increment the
3920 // full collection counter.
3921 increment_old_marking_cycles_started();
3922 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3923 }
3924
3925 _gc_tracer_stw->report_yc_type(yc_type());
3926
3927 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3928
3929 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3930 workers()->active_workers() : 1);
3931 double pause_start_sec = os::elapsedTime();
3932 g1_policy()->phase_times()->note_gc_start(active_workers);
3933 log_gc_header();
3934
3935 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3936 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3937
3938 // If the secondary_free_list is not empty, append it to the
3939 // free_list. No need to wait for the cleanup operation to finish;
3940 // the region allocation code will check the secondary_free_list
3941 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3942 // set, skip this step so that the region allocation code has to
3943 // get entries from the secondary_free_list.
3944 if (!G1StressConcRegionFreeing) {
3945 append_secondary_free_list_if_not_empty_with_lock();
3946 }
3947
3948 assert(check_young_list_well_formed(), "young list should be well formed");
3949 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3950 "sanity check");
3951
3952 // Don't dynamically change the number of GC threads this early. A value of
3953 // 0 is used to indicate serial work. When parallel work is done,
3954 // it will be set.
3955
3956 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3957 IsGCActiveMark x;
3958
3959 gc_prologue(false);
3960 increment_total_collections(false /* full gc */);
3961 increment_gc_time_stamp();
3962
3963 verify_before_gc();
3964
3965 COMPILER2_PRESENT(DerivedPointerTable::clear());
3966
3967 // Please see comment in g1CollectedHeap.hpp and
3968 // G1CollectedHeap::ref_processing_init() to see how
3969 // reference processing currently works in G1.
3970
3971 // Enable discovery in the STW reference processor
3972 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3973 true /*verify_no_refs*/);
3974
3975 {
3976 // We want to temporarily turn off discovery by the
3977 // CM ref processor, if necessary, and turn it back on
3978 // on again later if we do. Using a scoped
3979 // NoRefDiscovery object will do this.
3980 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3981
3982 // Forget the current alloc region (we might even choose it to be part
3983 // of the collection set!).
3984 release_mutator_alloc_region();
3985
3986 // We should call this after we retire the mutator alloc
3987 // region(s) so that all the ALLOC / RETIRE events are generated
3988 // before the start GC event.
3989 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3990
3991 // This timing is only used by the ergonomics to handle our pause target.
3992 // It is unclear why this should not include the full pause. We will
3993 // investigate this in CR 7178365.
3994 //
3995 // Preserving the old comment here if that helps the investigation:
3996 //
3997 // The elapsed time induced by the start time below deliberately elides
3998 // the possible verification above.
3999 double sample_start_time_sec = os::elapsedTime();
4000
4001 #if YOUNG_LIST_VERBOSE
4002 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4003 _young_list->print();
4004 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4005 #endif // YOUNG_LIST_VERBOSE
4006
4007 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4008
4009 double scan_wait_start = os::elapsedTime();
4010 // We have to wait until the CM threads finish scanning the
4011 // root regions as it's the only way to ensure that all the
4012 // objects on them have been correctly scanned before we start
4013 // moving them during the GC.
4014 bool waited = _cm->root_regions()->wait_until_scan_finished();
4015 double wait_time_ms = 0.0;
4016 if (waited) {
4017 double scan_wait_end = os::elapsedTime();
4018 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4019 }
4020 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4021
4022 #if YOUNG_LIST_VERBOSE
4023 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4024 _young_list->print();
4025 #endif // YOUNG_LIST_VERBOSE
4026
4027 if (g1_policy()->during_initial_mark_pause()) {
4028 concurrent_mark()->checkpointRootsInitialPre();
4029 }
4030
4031 #if YOUNG_LIST_VERBOSE
4032 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4033 _young_list->print();
4034 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4035 #endif // YOUNG_LIST_VERBOSE
4036
4037 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4038
4039 _cm->note_start_of_gc();
4040 // We should not verify the per-thread SATB buffers given that
4041 // we have not filtered them yet (we'll do so during the
4042 // GC). We also call this after finalize_cset() to
4043 // ensure that the CSet has been finalized.
4044 _cm->verify_no_cset_oops(true /* verify_stacks */,
4045 true /* verify_enqueued_buffers */,
4046 false /* verify_thread_buffers */,
4047 true /* verify_fingers */);
4048
4049 if (_hr_printer.is_active()) {
4050 HeapRegion* hr = g1_policy()->collection_set();
4051 while (hr != NULL) {
4052 G1HRPrinter::RegionType type;
4053 if (!hr->is_young()) {
4054 type = G1HRPrinter::Old;
4055 } else if (hr->is_survivor()) {
4056 type = G1HRPrinter::Survivor;
4057 } else {
4058 type = G1HRPrinter::Eden;
4059 }
4060 _hr_printer.cset(hr);
4061 hr = hr->next_in_collection_set();
4062 }
4063 }
4064
4065 #ifdef ASSERT
4066 VerifyCSetClosure cl;
4067 collection_set_iterate(&cl);
4068 #endif // ASSERT
4069
4070 setup_surviving_young_words();
4071
4072 // Initialize the GC alloc regions.
4073 init_gc_alloc_regions(evacuation_info);
4074
4075 // Actually do the work...
4076 evacuate_collection_set(evacuation_info);
4077
4078 // We do this to mainly verify the per-thread SATB buffers
4079 // (which have been filtered by now) since we didn't verify
4080 // them earlier. No point in re-checking the stacks / enqueued
4081 // buffers given that the CSet has not changed since last time
4082 // we checked.
4083 _cm->verify_no_cset_oops(false /* verify_stacks */,
4084 false /* verify_enqueued_buffers */,
4085 true /* verify_thread_buffers */,
4086 true /* verify_fingers */);
4087
4088 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4089 g1_policy()->clear_collection_set();
4090
4091 cleanup_surviving_young_words();
4092
4093 // Start a new incremental collection set for the next pause.
4094 g1_policy()->start_incremental_cset_building();
4095
4096 // Clear the _cset_fast_test bitmap in anticipation of adding
4097 // regions to the incremental collection set for the next
4098 // evacuation pause.
4099 clear_cset_fast_test();
4100
4101 _young_list->reset_sampled_info();
4102
4103 // Don't check the whole heap at this point as the
4104 // GC alloc regions from this pause have been tagged
4105 // as survivors and moved on to the survivor list.
4106 // Survivor regions will fail the !is_young() check.
4107 assert(check_young_list_empty(false /* check_heap */),
4108 "young list should be empty");
4109
4110 #if YOUNG_LIST_VERBOSE
4111 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4112 _young_list->print();
4113 #endif // YOUNG_LIST_VERBOSE
4114
4115 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4116 _young_list->first_survivor_region(),
4117 _young_list->last_survivor_region());
4118
4119 _young_list->reset_auxilary_lists();
4120
4121 if (evacuation_failed()) {
4122 _summary_bytes_used = recalculate_used();
4123 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4124 for (uint i = 0; i < n_queues; i++) {
4125 if (_evacuation_failed_info_array[i].has_failed()) {
4126 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4127 }
4128 }
4129 } else {
4130 // The "used" of the the collection set have already been subtracted
4131 // when they were freed. Add in the bytes evacuated.
4132 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4133 }
4134
4135 if (g1_policy()->during_initial_mark_pause()) {
4136 // We have to do this before we notify the CM threads that
4137 // they can start working to make sure that all the
4138 // appropriate initialization is done on the CM object.
4139 concurrent_mark()->checkpointRootsInitialPost();
4140 set_marking_started();
4141 // Note that we don't actually trigger the CM thread at
4142 // this point. We do that later when we're sure that
4143 // the current thread has completed its logging output.
4144 }
4145
4146 allocate_dummy_regions();
4147
4148 #if YOUNG_LIST_VERBOSE
4149 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4150 _young_list->print();
4151 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4152 #endif // YOUNG_LIST_VERBOSE
4153
4154 init_mutator_alloc_region();
4155
4156 {
4157 size_t expand_bytes = g1_policy()->expansion_amount();
4158 if (expand_bytes > 0) {
4159 size_t bytes_before = capacity();
4160 // No need for an ergo verbose message here,
4161 // expansion_amount() does this when it returns a value > 0.
4162 if (!expand(expand_bytes)) {
4163 // We failed to expand the heap so let's verify that
4164 // committed/uncommitted amount match the backing store
4165 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4166 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4167 }
4168 }
4169 }
4170
4171 // We redo the verification but now wrt to the new CSet which
4172 // has just got initialized after the previous CSet was freed.
4173 _cm->verify_no_cset_oops(true /* verify_stacks */,
4174 true /* verify_enqueued_buffers */,
4175 true /* verify_thread_buffers */,
4176 true /* verify_fingers */);
4177 _cm->note_end_of_gc();
4178
4179 // This timing is only used by the ergonomics to handle our pause target.
4180 // It is unclear why this should not include the full pause. We will
4181 // investigate this in CR 7178365.
4182 double sample_end_time_sec = os::elapsedTime();
4183 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4184 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4185
4186 MemoryService::track_memory_usage();
4187
4188 // In prepare_for_verify() below we'll need to scan the deferred
4189 // update buffers to bring the RSets up-to-date if
4190 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4191 // the update buffers we'll probably need to scan cards on the
4192 // regions we just allocated to (i.e., the GC alloc
4193 // regions). However, during the last GC we called
4194 // set_saved_mark() on all the GC alloc regions, so card
4195 // scanning might skip the [saved_mark_word()...top()] area of
4196 // those regions (i.e., the area we allocated objects into
4197 // during the last GC). But it shouldn't. Given that
4198 // saved_mark_word() is conditional on whether the GC time stamp
4199 // on the region is current or not, by incrementing the GC time
4200 // stamp here we invalidate all the GC time stamps on all the
4201 // regions and saved_mark_word() will simply return top() for
4202 // all the regions. This is a nicer way of ensuring this rather
4203 // than iterating over the regions and fixing them. In fact, the
4204 // GC time stamp increment here also ensures that
4205 // saved_mark_word() will return top() between pauses, i.e.,
4206 // during concurrent refinement. So we don't need the
4207 // is_gc_active() check to decided which top to use when
4208 // scanning cards (see CR 7039627).
4209 increment_gc_time_stamp();
4210
4211 verify_after_gc();
4212
4213 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4214 ref_processor_stw()->verify_no_references_recorded();
4215
4216 // CM reference discovery will be re-enabled if necessary.
4217 }
4218
4219 // We should do this after we potentially expand the heap so
4220 // that all the COMMIT events are generated before the end GC
4221 // event, and after we retire the GC alloc regions so that all
4222 // RETIRE events are generated before the end GC event.
4223 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4224
4225 if (mark_in_progress()) {
4226 concurrent_mark()->update_g1_committed();
4227 }
4228
4229 #ifdef TRACESPINNING
4230 ParallelTaskTerminator::print_termination_counts();
4231 #endif
4232
4233 gc_epilogue(false);
4234 }
4235
4236 // Print the remainder of the GC log output.
4237 log_gc_footer(os::elapsedTime() - pause_start_sec);
4238
4239 // It is not yet to safe to tell the concurrent mark to
4240 // start as we have some optional output below. We don't want the
4241 // output from the concurrent mark thread interfering with this
4242 // logging output either.
4243
4244 _hrs.verify_optional();
4245 verify_region_sets_optional();
4246
4247 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4248 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4249
4250 print_heap_after_gc();
4251 trace_heap_after_gc(_gc_tracer_stw);
4252
4253 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4254 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4255 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4256 // before any GC notifications are raised.
4257 g1mm()->update_sizes();
4258
4259 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4260 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4261 _gc_timer_stw->register_gc_end(os::elapsed_counter());
4262 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4263 }
4264 // It should now be safe to tell the concurrent mark thread to start
4265 // without its logging output interfering with the logging output
4266 // that came from the pause.
4267
4268 if (should_start_conc_mark) {
4269 // CAUTION: after the doConcurrentMark() call below,
4270 // the concurrent marking thread(s) could be running
4271 // concurrently with us. Make sure that anything after
4272 // this point does not assume that we are the only GC thread
4273 // running. Note: of course, the actual marking work will
4274 // not start until the safepoint itself is released in
4275 // ConcurrentGCThread::safepoint_desynchronize().
4276 doConcurrentMark();
4277 }
4278
4279 return true;
4280 }
4281
4282 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4283 {
4284 size_t gclab_word_size;
4285 switch (purpose) {
4286 case GCAllocForSurvived:
4287 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4288 break;
4289 case GCAllocForTenured:
4290 gclab_word_size = _old_plab_stats.desired_plab_sz();
4291 break;
4292 default:
4293 assert(false, "unknown GCAllocPurpose");
4294 gclab_word_size = _old_plab_stats.desired_plab_sz();
4295 break;
4296 }
4297
4298 // Prevent humongous PLAB sizes for two reasons:
4299 // * PLABs are allocated using a similar paths as oops, but should
4300 // never be in a humongous region
4301 // * Allowing humongous PLABs needlessly churns the region free lists
4302 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4303 }
4304
4305 void G1CollectedHeap::init_mutator_alloc_region() {
4306 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4307 _mutator_alloc_region.init();
4308 }
4309
4310 void G1CollectedHeap::release_mutator_alloc_region() {
4311 _mutator_alloc_region.release();
4312 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4313 }
4314
4315 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4316 assert_at_safepoint(true /* should_be_vm_thread */);
4317
4318 _survivor_gc_alloc_region.init();
4319 _old_gc_alloc_region.init();
4320 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4321 _retained_old_gc_alloc_region = NULL;
4322
4323 // We will discard the current GC alloc region if:
4324 // a) it's in the collection set (it can happen!),
4325 // b) it's already full (no point in using it),
4326 // c) it's empty (this means that it was emptied during
4327 // a cleanup and it should be on the free list now), or
4328 // d) it's humongous (this means that it was emptied
4329 // during a cleanup and was added to the free list, but
4330 // has been subsequently used to allocate a humongous
4331 // object that may be less than the region size).
4332 if (retained_region != NULL &&
4333 !retained_region->in_collection_set() &&
4334 !(retained_region->top() == retained_region->end()) &&
4335 !retained_region->is_empty() &&
4336 !retained_region->isHumongous()) {
4337 retained_region->set_saved_mark();
4338 // The retained region was added to the old region set when it was
4339 // retired. We have to remove it now, since we don't allow regions
4340 // we allocate to in the region sets. We'll re-add it later, when
4341 // it's retired again.
4342 _old_set.remove(retained_region);
4343 bool during_im = g1_policy()->during_initial_mark_pause();
4344 retained_region->note_start_of_copying(during_im);
4345 _old_gc_alloc_region.set(retained_region);
4346 _hr_printer.reuse(retained_region);
4347 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4348 }
4349 }
4350
4351 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4352 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4353 _old_gc_alloc_region.count());
4354 _survivor_gc_alloc_region.release();
4355 // If we have an old GC alloc region to release, we'll save it in
4356 // _retained_old_gc_alloc_region. If we don't
4357 // _retained_old_gc_alloc_region will become NULL. This is what we
4358 // want either way so no reason to check explicitly for either
4359 // condition.
4360 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4361
4362 if (ResizePLAB) {
4363 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4364 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4365 }
4366 }
4367
4368 void G1CollectedHeap::abandon_gc_alloc_regions() {
4369 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4370 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4371 _retained_old_gc_alloc_region = NULL;
4372 }
4373
4374 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4375 _drain_in_progress = false;
4376 set_evac_failure_closure(cl);
4377 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4378 }
4379
4380 void G1CollectedHeap::finalize_for_evac_failure() {
4381 assert(_evac_failure_scan_stack != NULL &&
4382 _evac_failure_scan_stack->length() == 0,
4383 "Postcondition");
4384 assert(!_drain_in_progress, "Postcondition");
4385 delete _evac_failure_scan_stack;
4386 _evac_failure_scan_stack = NULL;
4387 }
4388
4389 void G1CollectedHeap::remove_self_forwarding_pointers() {
4390 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4391
4392 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4393
4394 if (G1CollectedHeap::use_parallel_gc_threads()) {
4395 set_par_threads();
4396 workers()->run_task(&rsfp_task);
4397 set_par_threads(0);
4398 } else {
4399 rsfp_task.work(0);
4400 }
4401
4402 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4403
4404 // Reset the claim values in the regions in the collection set.
4405 reset_cset_heap_region_claim_values();
4406
4407 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4408
4409 // Now restore saved marks, if any.
4410 assert(_objs_with_preserved_marks.size() ==
4411 _preserved_marks_of_objs.size(), "Both or none.");
4412 while (!_objs_with_preserved_marks.is_empty()) {
4413 oop obj = _objs_with_preserved_marks.pop();
4414 markOop m = _preserved_marks_of_objs.pop();
4415 obj->set_mark(m);
4416 }
4417 _objs_with_preserved_marks.clear(true);
4418 _preserved_marks_of_objs.clear(true);
4419 }
4420
4421 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4422 _evac_failure_scan_stack->push(obj);
4423 }
4424
4425 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4426 assert(_evac_failure_scan_stack != NULL, "precondition");
4427
4428 while (_evac_failure_scan_stack->length() > 0) {
4429 oop obj = _evac_failure_scan_stack->pop();
4430 _evac_failure_closure->set_region(heap_region_containing(obj));
4431 obj->oop_iterate_backwards(_evac_failure_closure);
4432 }
4433 }
4434
4435 oop
4436 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4437 oop old) {
4438 assert(obj_in_cs(old),
4439 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4440 (HeapWord*) old));
4441 markOop m = old->mark();
4442 oop forward_ptr = old->forward_to_atomic(old);
4443 if (forward_ptr == NULL) {
4444 // Forward-to-self succeeded.
4445 assert(_par_scan_state != NULL, "par scan state");
4446 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4447 uint queue_num = _par_scan_state->queue_num();
4448
4449 _evacuation_failed = true;
4450 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4451 if (_evac_failure_closure != cl) {
4452 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4453 assert(!_drain_in_progress,
4454 "Should only be true while someone holds the lock.");
4455 // Set the global evac-failure closure to the current thread's.
4456 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4457 set_evac_failure_closure(cl);
4458 // Now do the common part.
4459 handle_evacuation_failure_common(old, m);
4460 // Reset to NULL.
4461 set_evac_failure_closure(NULL);
4462 } else {
4463 // The lock is already held, and this is recursive.
4464 assert(_drain_in_progress, "This should only be the recursive case.");
4465 handle_evacuation_failure_common(old, m);
4466 }
4467 return old;
4468 } else {
4469 // Forward-to-self failed. Either someone else managed to allocate
4470 // space for this object (old != forward_ptr) or they beat us in
4471 // self-forwarding it (old == forward_ptr).
4472 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4473 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4474 "should not be in the CSet",
4475 (HeapWord*) old, (HeapWord*) forward_ptr));
4476 return forward_ptr;
4477 }
4478 }
4479
4480 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4481 preserve_mark_if_necessary(old, m);
4482
4483 HeapRegion* r = heap_region_containing(old);
4484 if (!r->evacuation_failed()) {
4485 r->set_evacuation_failed(true);
4486 _hr_printer.evac_failure(r);
4487 }
4488
4489 push_on_evac_failure_scan_stack(old);
4490
4491 if (!_drain_in_progress) {
4492 // prevent recursion in copy_to_survivor_space()
4493 _drain_in_progress = true;
4494 drain_evac_failure_scan_stack();
4495 _drain_in_progress = false;
4496 }
4497 }
4498
4499 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4500 assert(evacuation_failed(), "Oversaving!");
4501 // We want to call the "for_promotion_failure" version only in the
4502 // case of a promotion failure.
4503 if (m->must_be_preserved_for_promotion_failure(obj)) {
4504 _objs_with_preserved_marks.push(obj);
4505 _preserved_marks_of_objs.push(m);
4506 }
4507 }
4508
4509 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4510 size_t word_size) {
4511 if (purpose == GCAllocForSurvived) {
4512 HeapWord* result = survivor_attempt_allocation(word_size);
4513 if (result != NULL) {
4514 return result;
4515 } else {
4516 // Let's try to allocate in the old gen in case we can fit the
4517 // object there.
4518 return old_attempt_allocation(word_size);
4519 }
4520 } else {
4521 assert(purpose == GCAllocForTenured, "sanity");
4522 HeapWord* result = old_attempt_allocation(word_size);
4523 if (result != NULL) {
4524 return result;
4525 } else {
4526 // Let's try to allocate in the survivors in case we can fit the
4527 // object there.
4528 return survivor_attempt_allocation(word_size);
4529 }
4530 }
4531
4532 ShouldNotReachHere();
4533 // Trying to keep some compilers happy.
4534 return NULL;
4535 }
4536
4537 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4538 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4539
4540 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4541 : _g1h(g1h),
4542 _refs(g1h->task_queue(queue_num)),
4543 _dcq(&g1h->dirty_card_queue_set()),
4544 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4545 _g1_rem(g1h->g1_rem_set()),
4546 _hash_seed(17), _queue_num(queue_num),
4547 _term_attempts(0),
4548 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4549 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4550 _age_table(false),
4551 _strong_roots_time(0), _term_time(0),
4552 _alloc_buffer_waste(0), _undo_waste(0) {
4553 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4554 // we "sacrifice" entry 0 to keep track of surviving bytes for
4555 // non-young regions (where the age is -1)
4556 // We also add a few elements at the beginning and at the end in
4557 // an attempt to eliminate cache contention
4558 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4559 uint array_length = PADDING_ELEM_NUM +
4560 real_length +
4561 PADDING_ELEM_NUM;
4562 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4563 if (_surviving_young_words_base == NULL)
4564 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4565 "Not enough space for young surv histo.");
4566 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4567 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4568
4569 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4570 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4571
4572 _start = os::elapsedTime();
4573 }
4574
4575 void
4576 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4577 {
4578 st->print_raw_cr("GC Termination Stats");
4579 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4580 " ------waste (KiB)------");
4581 st->print_raw_cr("thr ms ms % ms % attempts"
4582 " total alloc undo");
4583 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4584 " ------- ------- -------");
4585 }
4586
4587 void
4588 G1ParScanThreadState::print_termination_stats(int i,
4589 outputStream* const st) const
4590 {
4591 const double elapsed_ms = elapsed_time() * 1000.0;
4592 const double s_roots_ms = strong_roots_time() * 1000.0;
4593 const double term_ms = term_time() * 1000.0;
4594 st->print_cr("%3d %9.2f %9.2f %6.2f "
4595 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4596 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4597 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4598 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4599 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4600 alloc_buffer_waste() * HeapWordSize / K,
4601 undo_waste() * HeapWordSize / K);
4602 }
4603
4604 #ifdef ASSERT
4605 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4606 assert(ref != NULL, "invariant");
4607 assert(UseCompressedOops, "sanity");
4608 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4609 oop p = oopDesc::load_decode_heap_oop(ref);
4610 assert(_g1h->is_in_g1_reserved(p),
4611 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4612 return true;
4613 }
4614
4615 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4616 assert(ref != NULL, "invariant");
4617 if (has_partial_array_mask(ref)) {
4618 // Must be in the collection set--it's already been copied.
4619 oop p = clear_partial_array_mask(ref);
4620 assert(_g1h->obj_in_cs(p),
4621 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4622 } else {
4623 oop p = oopDesc::load_decode_heap_oop(ref);
4624 assert(_g1h->is_in_g1_reserved(p),
4625 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4626 }
4627 return true;
4628 }
4629
4630 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4631 if (ref.is_narrow()) {
4632 return verify_ref((narrowOop*) ref);
4633 } else {
4634 return verify_ref((oop*) ref);
4635 }
4636 }
4637 #endif // ASSERT
4638
4639 void G1ParScanThreadState::trim_queue() {
4640 assert(_evac_cl != NULL, "not set");
4641 assert(_evac_failure_cl != NULL, "not set");
4642 assert(_partial_scan_cl != NULL, "not set");
4643
4644 StarTask ref;
4645 do {
4646 // Drain the overflow stack first, so other threads can steal.
4647 while (refs()->pop_overflow(ref)) {
4648 deal_with_reference(ref);
4649 }
4650
4651 while (refs()->pop_local(ref)) {
4652 deal_with_reference(ref);
4653 }
4654 } while (!refs()->is_empty());
4655 }
4656
4657 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4658 G1ParScanThreadState* par_scan_state) :
4659 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4660 _par_scan_state(par_scan_state),
4661 _worker_id(par_scan_state->queue_num()),
4662 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4663 _mark_in_progress(_g1->mark_in_progress()) { }
4664
4665 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4666 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4667 #ifdef ASSERT
4668 HeapRegion* hr = _g1->heap_region_containing(obj);
4669 assert(hr != NULL, "sanity");
4670 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4671 #endif // ASSERT
4672
4673 // We know that the object is not moving so it's safe to read its size.
4674 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4675 }
4676
4677 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4678 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4679 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4680 #ifdef ASSERT
4681 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4682 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4683 assert(from_obj != to_obj, "should not be self-forwarded");
4684
4685 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4686 assert(from_hr != NULL, "sanity");
4687 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4688
4689 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4690 assert(to_hr != NULL, "sanity");
4691 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4692 #endif // ASSERT
4693
4694 // The object might be in the process of being copied by another
4695 // worker so we cannot trust that its to-space image is
4696 // well-formed. So we have to read its size from its from-space
4697 // image which we know should not be changing.
4698 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4699 }
4700
4701 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4702 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4703 ::copy_to_survivor_space(oop old) {
4704 size_t word_sz = old->size();
4705 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4706 // +1 to make the -1 indexes valid...
4707 int young_index = from_region->young_index_in_cset()+1;
4708 assert( (from_region->is_young() && young_index > 0) ||
4709 (!from_region->is_young() && young_index == 0), "invariant" );
4710 G1CollectorPolicy* g1p = _g1->g1_policy();
4711 markOop m = old->mark();
4712 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4713 : m->age();
4714 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4715 word_sz);
4716 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4717 #ifndef PRODUCT
4718 // Should this evacuation fail?
4719 if (_g1->evacuation_should_fail()) {
4720 if (obj_ptr != NULL) {
4721 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4722 obj_ptr = NULL;
4723 }
4724 }
4725 #endif // !PRODUCT
4726
4727 if (obj_ptr == NULL) {
4728 // This will either forward-to-self, or detect that someone else has
4729 // installed a forwarding pointer.
4730 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4731 }
4732
4733 oop obj = oop(obj_ptr);
4734
4735 // We're going to allocate linearly, so might as well prefetch ahead.
4736 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4737
4738 oop forward_ptr = old->forward_to_atomic(obj);
4739 if (forward_ptr == NULL) {
4740 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4741 if (g1p->track_object_age(alloc_purpose)) {
4742 // We could simply do obj->incr_age(). However, this causes a
4743 // performance issue. obj->incr_age() will first check whether
4744 // the object has a displaced mark by checking its mark word;
4745 // getting the mark word from the new location of the object
4746 // stalls. So, given that we already have the mark word and we
4747 // are about to install it anyway, it's better to increase the
4748 // age on the mark word, when the object does not have a
4749 // displaced mark word. We're not expecting many objects to have
4750 // a displaced marked word, so that case is not optimized
4751 // further (it could be...) and we simply call obj->incr_age().
4752
4753 if (m->has_displaced_mark_helper()) {
4754 // in this case, we have to install the mark word first,
4755 // otherwise obj looks to be forwarded (the old mark word,
4756 // which contains the forward pointer, was copied)
4757 obj->set_mark(m);
4758 obj->incr_age();
4759 } else {
4760 m = m->incr_age();
4761 obj->set_mark(m);
4762 }
4763 _par_scan_state->age_table()->add(obj, word_sz);
4764 } else {
4765 obj->set_mark(m);
4766 }
4767
4768 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4769 surv_young_words[young_index] += word_sz;
4770
4771 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4772 // We keep track of the next start index in the length field of
4773 // the to-space object. The actual length can be found in the
4774 // length field of the from-space object.
4775 arrayOop(obj)->set_length(0);
4776 oop* old_p = set_partial_array_mask(old);
4777 _par_scan_state->push_on_queue(old_p);
4778 } else {
4779 // No point in using the slower heap_region_containing() method,
4780 // given that we know obj is in the heap.
4781 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4782 obj->oop_iterate_backwards(&_scanner);
4783 }
4784 } else {
4785 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4786 obj = forward_ptr;
4787 }
4788 return obj;
4789 }
4790
4791 template <class T>
4792 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4793 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4794 _scanned_klass->record_modified_oops();
4795 }
4796 }
4797
4798 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4799 template <class T>
4800 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4801 ::do_oop_work(T* p) {
4802 oop obj = oopDesc::load_decode_heap_oop(p);
4803 assert(barrier != G1BarrierRS || obj != NULL,
4804 "Precondition: G1BarrierRS implies obj is non-NULL");
4805
4806 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4807
4808 // here the null check is implicit in the cset_fast_test() test
4809 if (_g1->in_cset_fast_test(obj)) {
4810 oop forwardee;
4811 if (obj->is_forwarded()) {
4812 forwardee = obj->forwardee();
4813 } else {
4814 forwardee = copy_to_survivor_space(obj);
4815 }
4816 assert(forwardee != NULL, "forwardee should not be NULL");
4817 oopDesc::encode_store_heap_oop(p, forwardee);
4818 if (do_mark_object && forwardee != obj) {
4819 // If the object is self-forwarded we don't need to explicitly
4820 // mark it, the evacuation failure protocol will do so.
4821 mark_forwarded_object(obj, forwardee);
4822 }
4823
4824 // When scanning the RS, we only care about objs in CS.
4825 if (barrier == G1BarrierRS) {
4826 _par_scan_state->update_rs(_from, p, _worker_id);
4827 } else if (barrier == G1BarrierKlass) {
4828 do_klass_barrier(p, forwardee);
4829 }
4830 } else {
4831 // The object is not in collection set. If we're a root scanning
4832 // closure during an initial mark pause (i.e. do_mark_object will
4833 // be true) then attempt to mark the object.
4834 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4835 mark_object(obj);
4836 }
4837 }
4838
4839 if (barrier == G1BarrierEvac && obj != NULL) {
4840 _par_scan_state->update_rs(_from, p, _worker_id);
4841 }
4842
4843 if (do_gen_barrier && obj != NULL) {
4844 par_do_barrier(p);
4845 }
4846 }
4847
4848 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4849 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4850
4851 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4852 assert(has_partial_array_mask(p), "invariant");
4853 oop from_obj = clear_partial_array_mask(p);
4854
4855 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4856 assert(from_obj->is_objArray(), "must be obj array");
4857 objArrayOop from_obj_array = objArrayOop(from_obj);
4858 // The from-space object contains the real length.
4859 int length = from_obj_array->length();
4860
4861 assert(from_obj->is_forwarded(), "must be forwarded");
4862 oop to_obj = from_obj->forwardee();
4863 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4864 objArrayOop to_obj_array = objArrayOop(to_obj);
4865 // We keep track of the next start index in the length field of the
4866 // to-space object.
4867 int next_index = to_obj_array->length();
4868 assert(0 <= next_index && next_index < length,
4869 err_msg("invariant, next index: %d, length: %d", next_index, length));
4870
4871 int start = next_index;
4872 int end = length;
4873 int remainder = end - start;
4874 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4875 if (remainder > 2 * ParGCArrayScanChunk) {
4876 end = start + ParGCArrayScanChunk;
4877 to_obj_array->set_length(end);
4878 // Push the remainder before we process the range in case another
4879 // worker has run out of things to do and can steal it.
4880 oop* from_obj_p = set_partial_array_mask(from_obj);
4881 _par_scan_state->push_on_queue(from_obj_p);
4882 } else {
4883 assert(length == end, "sanity");
4884 // We'll process the final range for this object. Restore the length
4885 // so that the heap remains parsable in case of evacuation failure.
4886 to_obj_array->set_length(end);
4887 }
4888 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4889 // Process indexes [start,end). It will also process the header
4890 // along with the first chunk (i.e., the chunk with start == 0).
4891 // Note that at this point the length field of to_obj_array is not
4892 // correct given that we are using it to keep track of the next
4893 // start index. oop_iterate_range() (thankfully!) ignores the length
4894 // field and only relies on the start / end parameters. It does
4895 // however return the size of the object which will be incorrect. So
4896 // we have to ignore it even if we wanted to use it.
4897 to_obj_array->oop_iterate_range(&_scanner, start, end);
4898 }
4899
4900 class G1ParEvacuateFollowersClosure : public VoidClosure {
4901 protected:
4902 G1CollectedHeap* _g1h;
4903 G1ParScanThreadState* _par_scan_state;
4904 RefToScanQueueSet* _queues;
4905 ParallelTaskTerminator* _terminator;
4906
4907 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4908 RefToScanQueueSet* queues() { return _queues; }
4909 ParallelTaskTerminator* terminator() { return _terminator; }
4910
4911 public:
4912 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4913 G1ParScanThreadState* par_scan_state,
4914 RefToScanQueueSet* queues,
4915 ParallelTaskTerminator* terminator)
4916 : _g1h(g1h), _par_scan_state(par_scan_state),
4917 _queues(queues), _terminator(terminator) {}
4918
4919 void do_void();
4920
4921 private:
4922 inline bool offer_termination();
4923 };
4924
4925 bool G1ParEvacuateFollowersClosure::offer_termination() {
4926 G1ParScanThreadState* const pss = par_scan_state();
4927 pss->start_term_time();
4928 const bool res = terminator()->offer_termination();
4929 pss->end_term_time();
4930 return res;
4931 }
4932
4933 void G1ParEvacuateFollowersClosure::do_void() {
4934 StarTask stolen_task;
4935 G1ParScanThreadState* const pss = par_scan_state();
4936 pss->trim_queue();
4937
4938 do {
4939 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4940 assert(pss->verify_task(stolen_task), "sanity");
4941 if (stolen_task.is_narrow()) {
4942 pss->deal_with_reference((narrowOop*) stolen_task);
4943 } else {
4944 pss->deal_with_reference((oop*) stolen_task);
4945 }
4946
4947 // We've just processed a reference and we might have made
4948 // available new entries on the queues. So we have to make sure
4949 // we drain the queues as necessary.
4950 pss->trim_queue();
4951 }
4952 } while (!offer_termination());
4953
4954 pss->retire_alloc_buffers();
4955 }
4956
4957 class G1KlassScanClosure : public KlassClosure {
4958 G1ParCopyHelper* _closure;
4959 bool _process_only_dirty;
4960 int _count;
4961 public:
4962 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4963 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4964 void do_klass(Klass* klass) {
4965 // If the klass has not been dirtied we know that there's
4966 // no references into the young gen and we can skip it.
4967 if (!_process_only_dirty || klass->has_modified_oops()) {
4968 // Clean the klass since we're going to scavenge all the metadata.
4969 klass->clear_modified_oops();
4970
4971 // Tell the closure that this klass is the Klass to scavenge
4972 // and is the one to dirty if oops are left pointing into the young gen.
4973 _closure->set_scanned_klass(klass);
4974
4975 klass->oops_do(_closure);
4976
4977 _closure->set_scanned_klass(NULL);
4978 }
4979 _count++;
4980 }
4981 };
4982
4983 class G1ParTask : public AbstractGangTask {
4984 protected:
4985 G1CollectedHeap* _g1h;
4986 RefToScanQueueSet *_queues;
4987 ParallelTaskTerminator _terminator;
4988 uint _n_workers;
4989
4990 Mutex _stats_lock;
4991 Mutex* stats_lock() { return &_stats_lock; }
4992
4993 size_t getNCards() {
4994 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4995 / G1BlockOffsetSharedArray::N_bytes;
4996 }
4997
4998 public:
4999 G1ParTask(G1CollectedHeap* g1h,
5000 RefToScanQueueSet *task_queues)
5001 : AbstractGangTask("G1 collection"),
5002 _g1h(g1h),
5003 _queues(task_queues),
5004 _terminator(0, _queues),
5005 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
5006 {}
5007
5008 RefToScanQueueSet* queues() { return _queues; }
5009
5010 RefToScanQueue *work_queue(int i) {
5011 return queues()->queue(i);
5012 }
5013
5014 ParallelTaskTerminator* terminator() { return &_terminator; }
5015
5016 virtual void set_for_termination(int active_workers) {
5017 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5018 // in the young space (_par_seq_tasks) in the G1 heap
5019 // for SequentialSubTasksDone.
5020 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5021 // both of which need setting by set_n_termination().
5022 _g1h->SharedHeap::set_n_termination(active_workers);
5023 _g1h->set_n_termination(active_workers);
5024 terminator()->reset_for_reuse(active_workers);
5025 _n_workers = active_workers;
5026 }
5027
5028 void work(uint worker_id) {
5029 if (worker_id >= _n_workers) return; // no work needed this round
5030
5031 double start_time_ms = os::elapsedTime() * 1000.0;
5032 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5033
5034 {
5035 ResourceMark rm;
5036 HandleMark hm;
5037
5038 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5039
5040 G1ParScanThreadState pss(_g1h, worker_id);
5041 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5042 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5043 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5044
5045 pss.set_evac_closure(&scan_evac_cl);
5046 pss.set_evac_failure_closure(&evac_failure_cl);
5047 pss.set_partial_scan_closure(&partial_scan_cl);
5048
5049 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5050 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5051
5052 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5053 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5054
5055 bool only_young = _g1h->g1_policy()->gcs_are_young();
5056 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5057 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5058
5059 OopClosure* scan_root_cl = &only_scan_root_cl;
5060 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5061
5062 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5063 // We also need to mark copied objects.
5064 scan_root_cl = &scan_mark_root_cl;
5065 scan_klasses_cl = &scan_mark_klasses_cl_s;
5066 }
5067
5068 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5069
5070 // Don't scan the scavengable methods in the code cache as part
5071 // of strong root scanning. The code roots that point into a
5072 // region in the collection set are scanned when we scan the
5073 // region's RSet.
5074 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5075
5076 pss.start_strong_roots();
5077 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5078 SharedHeap::ScanningOption(so),
5079 scan_root_cl,
5080 &push_heap_rs_cl,
5081 scan_klasses_cl,
5082 worker_id);
5083 pss.end_strong_roots();
5084
5085 {
5086 double start = os::elapsedTime();
5087 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5088 evac.do_void();
5089 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5090 double term_ms = pss.term_time()*1000.0;
5091 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5092 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5093 }
5094 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5095 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5096
5097 if (ParallelGCVerbose) {
5098 MutexLocker x(stats_lock());
5099 pss.print_termination_stats(worker_id);
5100 }
5101
5102 assert(pss.refs()->is_empty(), "should be empty");
5103
5104 // Close the inner scope so that the ResourceMark and HandleMark
5105 // destructors are executed here and are included as part of the
5106 // "GC Worker Time".
5107 }
5108
5109 double end_time_ms = os::elapsedTime() * 1000.0;
5110 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5111 }
5112 };
5113
5114 // *** Common G1 Evacuation Stuff
5115
5116 // This method is run in a GC worker.
5117
5118 void
5119 G1CollectedHeap::
5120 g1_process_strong_roots(bool is_scavenging,
5121 ScanningOption so,
5122 OopClosure* scan_non_heap_roots,
5123 OopsInHeapRegionClosure* scan_rs,
5124 G1KlassScanClosure* scan_klasses,
5125 int worker_i) {
5126
5127 // First scan the strong roots
5128 double ext_roots_start = os::elapsedTime();
5129 double closure_app_time_sec = 0.0;
5130
5131 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5132
5133 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5134 // Walk the code cache/strong code roots w/o buffering, because StarTask
5135 // cannot handle unaligned oop locations.
5136 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5137
5138 process_strong_roots(false, // no scoping; this is parallel code
5139 is_scavenging, so,
5140 &buf_scan_non_heap_roots,
5141 &eager_scan_code_roots,
5142 scan_klasses
5143 );
5144
5145 // Now the CM ref_processor roots.
5146 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5147 // We need to treat the discovered reference lists of the
5148 // concurrent mark ref processor as roots and keep entries
5149 // (which are added by the marking threads) on them live
5150 // until they can be processed at the end of marking.
5151 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5152 }
5153
5154 // Finish up any enqueued closure apps (attributed as object copy time).
5155 buf_scan_non_heap_roots.done();
5156
5157 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5158
5159 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5160
5161 double ext_root_time_ms =
5162 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5163
5164 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5165
5166 // During conc marking we have to filter the per-thread SATB buffers
5167 // to make sure we remove any oops into the CSet (which will show up
5168 // as implicitly live).
5169 double satb_filtering_ms = 0.0;
5170 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5171 if (mark_in_progress()) {
5172 double satb_filter_start = os::elapsedTime();
5173
5174 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5175
5176 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5177 }
5178 }
5179 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5180
5181 // If this is an initial mark pause, and we're not scanning
5182 // the entire code cache, we need to mark the oops in the
5183 // strong code root lists for the regions that are not in
5184 // the collection set.
5185 // Note all threads participate in this set of root tasks.
5186 double mark_strong_code_roots_ms = 0.0;
5187 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5188 double mark_strong_roots_start = os::elapsedTime();
5189 mark_strong_code_roots(worker_i);
5190 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5191 }
5192 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5193
5194 // Now scan the complement of the collection set.
5195 if (scan_rs != NULL) {
5196 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5197 }
5198 _process_strong_tasks->all_tasks_completed();
5199 }
5200
5201 void
5202 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5203 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5204 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5205 }
5206
5207 // Weak Reference Processing support
5208
5209 // An always "is_alive" closure that is used to preserve referents.
5210 // If the object is non-null then it's alive. Used in the preservation
5211 // of referent objects that are pointed to by reference objects
5212 // discovered by the CM ref processor.
5213 class G1AlwaysAliveClosure: public BoolObjectClosure {
5214 G1CollectedHeap* _g1;
5215 public:
5216 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5217 bool do_object_b(oop p) {
5218 if (p != NULL) {
5219 return true;
5220 }
5221 return false;
5222 }
5223 };
5224
5225 bool G1STWIsAliveClosure::do_object_b(oop p) {
5226 // An object is reachable if it is outside the collection set,
5227 // or is inside and copied.
5228 return !_g1->obj_in_cs(p) || p->is_forwarded();
5229 }
5230
5231 // Non Copying Keep Alive closure
5232 class G1KeepAliveClosure: public OopClosure {
5233 G1CollectedHeap* _g1;
5234 public:
5235 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5236 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5237 void do_oop( oop* p) {
5238 oop obj = *p;
5239
5240 if (_g1->obj_in_cs(obj)) {
5241 assert( obj->is_forwarded(), "invariant" );
5242 *p = obj->forwardee();
5243 }
5244 }
5245 };
5246
5247 // Copying Keep Alive closure - can be called from both
5248 // serial and parallel code as long as different worker
5249 // threads utilize different G1ParScanThreadState instances
5250 // and different queues.
5251
5252 class G1CopyingKeepAliveClosure: public OopClosure {
5253 G1CollectedHeap* _g1h;
5254 OopClosure* _copy_non_heap_obj_cl;
5255 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5256 G1ParScanThreadState* _par_scan_state;
5257
5258 public:
5259 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5260 OopClosure* non_heap_obj_cl,
5261 OopsInHeapRegionClosure* metadata_obj_cl,
5262 G1ParScanThreadState* pss):
5263 _g1h(g1h),
5264 _copy_non_heap_obj_cl(non_heap_obj_cl),
5265 _copy_metadata_obj_cl(metadata_obj_cl),
5266 _par_scan_state(pss)
5267 {}
5268
5269 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5270 virtual void do_oop( oop* p) { do_oop_work(p); }
5271
5272 template <class T> void do_oop_work(T* p) {
5273 oop obj = oopDesc::load_decode_heap_oop(p);
5274
5275 if (_g1h->obj_in_cs(obj)) {
5276 // If the referent object has been forwarded (either copied
5277 // to a new location or to itself in the event of an
5278 // evacuation failure) then we need to update the reference
5279 // field and, if both reference and referent are in the G1
5280 // heap, update the RSet for the referent.
5281 //
5282 // If the referent has not been forwarded then we have to keep
5283 // it alive by policy. Therefore we have copy the referent.
5284 //
5285 // If the reference field is in the G1 heap then we can push
5286 // on the PSS queue. When the queue is drained (after each
5287 // phase of reference processing) the object and it's followers
5288 // will be copied, the reference field set to point to the
5289 // new location, and the RSet updated. Otherwise we need to
5290 // use the the non-heap or metadata closures directly to copy
5291 // the referent object and update the pointer, while avoiding
5292 // updating the RSet.
5293
5294 if (_g1h->is_in_g1_reserved(p)) {
5295 _par_scan_state->push_on_queue(p);
5296 } else {
5297 assert(!ClassLoaderDataGraph::contains((address)p),
5298 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5299 PTR_FORMAT, p));
5300 _copy_non_heap_obj_cl->do_oop(p);
5301 }
5302 }
5303 }
5304 };
5305
5306 // Serial drain queue closure. Called as the 'complete_gc'
5307 // closure for each discovered list in some of the
5308 // reference processing phases.
5309
5310 class G1STWDrainQueueClosure: public VoidClosure {
5311 protected:
5312 G1CollectedHeap* _g1h;
5313 G1ParScanThreadState* _par_scan_state;
5314
5315 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5316
5317 public:
5318 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5319 _g1h(g1h),
5320 _par_scan_state(pss)
5321 { }
5322
5323 void do_void() {
5324 G1ParScanThreadState* const pss = par_scan_state();
5325 pss->trim_queue();
5326 }
5327 };
5328
5329 // Parallel Reference Processing closures
5330
5331 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5332 // processing during G1 evacuation pauses.
5333
5334 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5335 private:
5336 G1CollectedHeap* _g1h;
5337 RefToScanQueueSet* _queues;
5338 FlexibleWorkGang* _workers;
5339 int _active_workers;
5340
5341 public:
5342 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5343 FlexibleWorkGang* workers,
5344 RefToScanQueueSet *task_queues,
5345 int n_workers) :
5346 _g1h(g1h),
5347 _queues(task_queues),
5348 _workers(workers),
5349 _active_workers(n_workers)
5350 {
5351 assert(n_workers > 0, "shouldn't call this otherwise");
5352 }
5353
5354 // Executes the given task using concurrent marking worker threads.
5355 virtual void execute(ProcessTask& task);
5356 virtual void execute(EnqueueTask& task);
5357 };
5358
5359 // Gang task for possibly parallel reference processing
5360
5361 class G1STWRefProcTaskProxy: public AbstractGangTask {
5362 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5363 ProcessTask& _proc_task;
5364 G1CollectedHeap* _g1h;
5365 RefToScanQueueSet *_task_queues;
5366 ParallelTaskTerminator* _terminator;
5367
5368 public:
5369 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5370 G1CollectedHeap* g1h,
5371 RefToScanQueueSet *task_queues,
5372 ParallelTaskTerminator* terminator) :
5373 AbstractGangTask("Process reference objects in parallel"),
5374 _proc_task(proc_task),
5375 _g1h(g1h),
5376 _task_queues(task_queues),
5377 _terminator(terminator)
5378 {}
5379
5380 virtual void work(uint worker_id) {
5381 // The reference processing task executed by a single worker.
5382 ResourceMark rm;
5383 HandleMark hm;
5384
5385 G1STWIsAliveClosure is_alive(_g1h);
5386
5387 G1ParScanThreadState pss(_g1h, worker_id);
5388
5389 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5390 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5391 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5392
5393 pss.set_evac_closure(&scan_evac_cl);
5394 pss.set_evac_failure_closure(&evac_failure_cl);
5395 pss.set_partial_scan_closure(&partial_scan_cl);
5396
5397 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5398 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5399
5400 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5401 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5402
5403 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5404 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5405
5406 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5407 // We also need to mark copied objects.
5408 copy_non_heap_cl = ©_mark_non_heap_cl;
5409 copy_metadata_cl = ©_mark_metadata_cl;
5410 }
5411
5412 // Keep alive closure.
5413 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5414
5415 // Complete GC closure
5416 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5417
5418 // Call the reference processing task's work routine.
5419 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5420
5421 // Note we cannot assert that the refs array is empty here as not all
5422 // of the processing tasks (specifically phase2 - pp2_work) execute
5423 // the complete_gc closure (which ordinarily would drain the queue) so
5424 // the queue may not be empty.
5425 }
5426 };
5427
5428 // Driver routine for parallel reference processing.
5429 // Creates an instance of the ref processing gang
5430 // task and has the worker threads execute it.
5431 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5432 assert(_workers != NULL, "Need parallel worker threads.");
5433
5434 ParallelTaskTerminator terminator(_active_workers, _queues);
5435 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5436
5437 _g1h->set_par_threads(_active_workers);
5438 _workers->run_task(&proc_task_proxy);
5439 _g1h->set_par_threads(0);
5440 }
5441
5442 // Gang task for parallel reference enqueueing.
5443
5444 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5445 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5446 EnqueueTask& _enq_task;
5447
5448 public:
5449 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5450 AbstractGangTask("Enqueue reference objects in parallel"),
5451 _enq_task(enq_task)
5452 { }
5453
5454 virtual void work(uint worker_id) {
5455 _enq_task.work(worker_id);
5456 }
5457 };
5458
5459 // Driver routine for parallel reference enqueueing.
5460 // Creates an instance of the ref enqueueing gang
5461 // task and has the worker threads execute it.
5462
5463 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5464 assert(_workers != NULL, "Need parallel worker threads.");
5465
5466 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5467
5468 _g1h->set_par_threads(_active_workers);
5469 _workers->run_task(&enq_task_proxy);
5470 _g1h->set_par_threads(0);
5471 }
5472
5473 // End of weak reference support closures
5474
5475 // Abstract task used to preserve (i.e. copy) any referent objects
5476 // that are in the collection set and are pointed to by reference
5477 // objects discovered by the CM ref processor.
5478
5479 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5480 protected:
5481 G1CollectedHeap* _g1h;
5482 RefToScanQueueSet *_queues;
5483 ParallelTaskTerminator _terminator;
5484 uint _n_workers;
5485
5486 public:
5487 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5488 AbstractGangTask("ParPreserveCMReferents"),
5489 _g1h(g1h),
5490 _queues(task_queues),
5491 _terminator(workers, _queues),
5492 _n_workers(workers)
5493 { }
5494
5495 void work(uint worker_id) {
5496 ResourceMark rm;
5497 HandleMark hm;
5498
5499 G1ParScanThreadState pss(_g1h, worker_id);
5500 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5501 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5502 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5503
5504 pss.set_evac_closure(&scan_evac_cl);
5505 pss.set_evac_failure_closure(&evac_failure_cl);
5506 pss.set_partial_scan_closure(&partial_scan_cl);
5507
5508 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5509
5510
5511 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5512 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5513
5514 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5515 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5516
5517 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5518 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5519
5520 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5521 // We also need to mark copied objects.
5522 copy_non_heap_cl = ©_mark_non_heap_cl;
5523 copy_metadata_cl = ©_mark_metadata_cl;
5524 }
5525
5526 // Is alive closure
5527 G1AlwaysAliveClosure always_alive(_g1h);
5528
5529 // Copying keep alive closure. Applied to referent objects that need
5530 // to be copied.
5531 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5532
5533 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5534
5535 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5536 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5537
5538 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5539 // So this must be true - but assert just in case someone decides to
5540 // change the worker ids.
5541 assert(0 <= worker_id && worker_id < limit, "sanity");
5542 assert(!rp->discovery_is_atomic(), "check this code");
5543
5544 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5545 for (uint idx = worker_id; idx < limit; idx += stride) {
5546 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5547
5548 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5549 while (iter.has_next()) {
5550 // Since discovery is not atomic for the CM ref processor, we
5551 // can see some null referent objects.
5552 iter.load_ptrs(DEBUG_ONLY(true));
5553 oop ref = iter.obj();
5554
5555 // This will filter nulls.
5556 if (iter.is_referent_alive()) {
5557 iter.make_referent_alive();
5558 }
5559 iter.move_to_next();
5560 }
5561 }
5562
5563 // Drain the queue - which may cause stealing
5564 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5565 drain_queue.do_void();
5566 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5567 assert(pss.refs()->is_empty(), "should be");
5568 }
5569 };
5570
5571 // Weak Reference processing during an evacuation pause (part 1).
5572 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5573 double ref_proc_start = os::elapsedTime();
5574
5575 ReferenceProcessor* rp = _ref_processor_stw;
5576 assert(rp->discovery_enabled(), "should have been enabled");
5577
5578 // Any reference objects, in the collection set, that were 'discovered'
5579 // by the CM ref processor should have already been copied (either by
5580 // applying the external root copy closure to the discovered lists, or
5581 // by following an RSet entry).
5582 //
5583 // But some of the referents, that are in the collection set, that these
5584 // reference objects point to may not have been copied: the STW ref
5585 // processor would have seen that the reference object had already
5586 // been 'discovered' and would have skipped discovering the reference,
5587 // but would not have treated the reference object as a regular oop.
5588 // As a result the copy closure would not have been applied to the
5589 // referent object.
5590 //
5591 // We need to explicitly copy these referent objects - the references
5592 // will be processed at the end of remarking.
5593 //
5594 // We also need to do this copying before we process the reference
5595 // objects discovered by the STW ref processor in case one of these
5596 // referents points to another object which is also referenced by an
5597 // object discovered by the STW ref processor.
5598
5599 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5600 no_of_gc_workers == workers()->active_workers(),
5601 "Need to reset active GC workers");
5602
5603 set_par_threads(no_of_gc_workers);
5604 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5605 no_of_gc_workers,
5606 _task_queues);
5607
5608 if (G1CollectedHeap::use_parallel_gc_threads()) {
5609 workers()->run_task(&keep_cm_referents);
5610 } else {
5611 keep_cm_referents.work(0);
5612 }
5613
5614 set_par_threads(0);
5615
5616 // Closure to test whether a referent is alive.
5617 G1STWIsAliveClosure is_alive(this);
5618
5619 // Even when parallel reference processing is enabled, the processing
5620 // of JNI refs is serial and performed serially by the current thread
5621 // rather than by a worker. The following PSS will be used for processing
5622 // JNI refs.
5623
5624 // Use only a single queue for this PSS.
5625 G1ParScanThreadState pss(this, 0);
5626
5627 // We do not embed a reference processor in the copying/scanning
5628 // closures while we're actually processing the discovered
5629 // reference objects.
5630 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5631 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5632 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5633
5634 pss.set_evac_closure(&scan_evac_cl);
5635 pss.set_evac_failure_closure(&evac_failure_cl);
5636 pss.set_partial_scan_closure(&partial_scan_cl);
5637
5638 assert(pss.refs()->is_empty(), "pre-condition");
5639
5640 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5641 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5642
5643 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5644 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5645
5646 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5647 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5648
5649 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5650 // We also need to mark copied objects.
5651 copy_non_heap_cl = ©_mark_non_heap_cl;
5652 copy_metadata_cl = ©_mark_metadata_cl;
5653 }
5654
5655 // Keep alive closure.
5656 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5657
5658 // Serial Complete GC closure
5659 G1STWDrainQueueClosure drain_queue(this, &pss);
5660
5661 // Setup the soft refs policy...
5662 rp->setup_policy(false);
5663
5664 ReferenceProcessorStats stats;
5665 if (!rp->processing_is_mt()) {
5666 // Serial reference processing...
5667 stats = rp->process_discovered_references(&is_alive,
5668 &keep_alive,
5669 &drain_queue,
5670 NULL,
5671 _gc_timer_stw);
5672 } else {
5673 // Parallel reference processing
5674 assert(rp->num_q() == no_of_gc_workers, "sanity");
5675 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5676
5677 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5678 stats = rp->process_discovered_references(&is_alive,
5679 &keep_alive,
5680 &drain_queue,
5681 &par_task_executor,
5682 _gc_timer_stw);
5683 }
5684
5685 _gc_tracer_stw->report_gc_reference_stats(stats);
5686 // We have completed copying any necessary live referent objects
5687 // (that were not copied during the actual pause) so we can
5688 // retire any active alloc buffers
5689 pss.retire_alloc_buffers();
5690 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5691
5692 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5693 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5694 }
5695
5696 // Weak Reference processing during an evacuation pause (part 2).
5697 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5698 double ref_enq_start = os::elapsedTime();
5699
5700 ReferenceProcessor* rp = _ref_processor_stw;
5701 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5702
5703 // Now enqueue any remaining on the discovered lists on to
5704 // the pending list.
5705 if (!rp->processing_is_mt()) {
5706 // Serial reference processing...
5707 rp->enqueue_discovered_references();
5708 } else {
5709 // Parallel reference enqueueing
5710
5711 assert(no_of_gc_workers == workers()->active_workers(),
5712 "Need to reset active workers");
5713 assert(rp->num_q() == no_of_gc_workers, "sanity");
5714 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5715
5716 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5717 rp->enqueue_discovered_references(&par_task_executor);
5718 }
5719
5720 rp->verify_no_references_recorded();
5721 assert(!rp->discovery_enabled(), "should have been disabled");
5722
5723 // FIXME
5724 // CM's reference processing also cleans up the string and symbol tables.
5725 // Should we do that here also? We could, but it is a serial operation
5726 // and could significantly increase the pause time.
5727
5728 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5729 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5730 }
5731
5732 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5733 _expand_heap_after_alloc_failure = true;
5734 _evacuation_failed = false;
5735
5736 // Should G1EvacuationFailureALot be in effect for this GC?
5737 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5738
5739 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5740
5741 // Disable the hot card cache.
5742 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5743 hot_card_cache->reset_hot_cache_claimed_index();
5744 hot_card_cache->set_use_cache(false);
5745
5746 uint n_workers;
5747 if (G1CollectedHeap::use_parallel_gc_threads()) {
5748 n_workers =
5749 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5750 workers()->active_workers(),
5751 Threads::number_of_non_daemon_threads());
5752 assert(UseDynamicNumberOfGCThreads ||
5753 n_workers == workers()->total_workers(),
5754 "If not dynamic should be using all the workers");
5755 workers()->set_active_workers(n_workers);
5756 set_par_threads(n_workers);
5757 } else {
5758 assert(n_par_threads() == 0,
5759 "Should be the original non-parallel value");
5760 n_workers = 1;
5761 }
5762
5763 G1ParTask g1_par_task(this, _task_queues);
5764
5765 init_for_evac_failure(NULL);
5766
5767 rem_set()->prepare_for_younger_refs_iterate(true);
5768
5769 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5770 double start_par_time_sec = os::elapsedTime();
5771 double end_par_time_sec;
5772
5773 {
5774 StrongRootsScope srs(this);
5775
5776 if (G1CollectedHeap::use_parallel_gc_threads()) {
5777 // The individual threads will set their evac-failure closures.
5778 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5779 // These tasks use ShareHeap::_process_strong_tasks
5780 assert(UseDynamicNumberOfGCThreads ||
5781 workers()->active_workers() == workers()->total_workers(),
5782 "If not dynamic should be using all the workers");
5783 workers()->run_task(&g1_par_task);
5784 } else {
5785 g1_par_task.set_for_termination(n_workers);
5786 g1_par_task.work(0);
5787 }
5788 end_par_time_sec = os::elapsedTime();
5789
5790 // Closing the inner scope will execute the destructor
5791 // for the StrongRootsScope object. We record the current
5792 // elapsed time before closing the scope so that time
5793 // taken for the SRS destructor is NOT included in the
5794 // reported parallel time.
5795 }
5796
5797 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5798 g1_policy()->phase_times()->record_par_time(par_time_ms);
5799
5800 double code_root_fixup_time_ms =
5801 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5802 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5803
5804 set_par_threads(0);
5805
5806 // Process any discovered reference objects - we have
5807 // to do this _before_ we retire the GC alloc regions
5808 // as we may have to copy some 'reachable' referent
5809 // objects (and their reachable sub-graphs) that were
5810 // not copied during the pause.
5811 process_discovered_references(n_workers);
5812
5813 // Weak root processing.
5814 {
5815 G1STWIsAliveClosure is_alive(this);
5816 G1KeepAliveClosure keep_alive(this);
5817 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5818 }
5819
5820 release_gc_alloc_regions(n_workers, evacuation_info);
5821 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5822
5823 // Reset and re-enable the hot card cache.
5824 // Note the counts for the cards in the regions in the
5825 // collection set are reset when the collection set is freed.
5826 hot_card_cache->reset_hot_cache();
5827 hot_card_cache->set_use_cache(true);
5828
5829 // Migrate the strong code roots attached to each region in
5830 // the collection set. Ideally we would like to do this
5831 // after we have finished the scanning/evacuation of the
5832 // strong code roots for a particular heap region.
5833 migrate_strong_code_roots();
5834
5835 if (g1_policy()->during_initial_mark_pause()) {
5836 // Reset the claim values set during marking the strong code roots
5837 reset_heap_region_claim_values();
5838 }
5839
5840 finalize_for_evac_failure();
5841
5842 if (evacuation_failed()) {
5843 remove_self_forwarding_pointers();
5844
5845 // Reset the G1EvacuationFailureALot counters and flags
5846 // Note: the values are reset only when an actual
5847 // evacuation failure occurs.
5848 NOT_PRODUCT(reset_evacuation_should_fail();)
5849 }
5850
5851 // Enqueue any remaining references remaining on the STW
5852 // reference processor's discovered lists. We need to do
5853 // this after the card table is cleaned (and verified) as
5854 // the act of enqueueing entries on to the pending list
5855 // will log these updates (and dirty their associated
5856 // cards). We need these updates logged to update any
5857 // RSets.
5858 enqueue_discovered_references(n_workers);
5859
5860 if (G1DeferredRSUpdate) {
5861 RedirtyLoggedCardTableEntryFastClosure redirty;
5862 dirty_card_queue_set().set_closure(&redirty);
5863 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5864
5865 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5866 dcq.merge_bufferlists(&dirty_card_queue_set());
5867 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5868 }
5869 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5870 }
5871
5872 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5873 size_t* pre_used,
5874 FreeRegionList* free_list,
5875 OldRegionSet* old_proxy_set,
5876 HumongousRegionSet* humongous_proxy_set,
5877 HRRSCleanupTask* hrrs_cleanup_task,
5878 bool par) {
5879 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5880 if (hr->isHumongous()) {
5881 assert(hr->startsHumongous(), "we should only see starts humongous");
5882 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5883 } else {
5884 _old_set.remove_with_proxy(hr, old_proxy_set);
5885 free_region(hr, pre_used, free_list, par);
5886 }
5887 } else {
5888 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5889 }
5890 }
5891
5892 void G1CollectedHeap::free_region(HeapRegion* hr,
5893 size_t* pre_used,
5894 FreeRegionList* free_list,
5895 bool par) {
5896 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5897 assert(!hr->is_empty(), "the region should not be empty");
5898 assert(free_list != NULL, "pre-condition");
5899
5900 // Clear the card counts for this region.
5901 // Note: we only need to do this if the region is not young
5902 // (since we don't refine cards in young regions).
5903 if (!hr->is_young()) {
5904 _cg1r->hot_card_cache()->reset_card_counts(hr);
5905 }
5906 *pre_used += hr->used();
5907 hr->hr_clear(par, true /* clear_space */);
5908 free_list->add_as_head(hr);
5909 }
5910
5911 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5912 size_t* pre_used,
5913 FreeRegionList* free_list,
5914 HumongousRegionSet* humongous_proxy_set,
5915 bool par) {
5916 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5917 assert(free_list != NULL, "pre-condition");
5918 assert(humongous_proxy_set != NULL, "pre-condition");
5919
5920 size_t hr_used = hr->used();
5921 size_t hr_capacity = hr->capacity();
5922 size_t hr_pre_used = 0;
5923 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5924 // We need to read this before we make the region non-humongous,
5925 // otherwise the information will be gone.
5926 uint last_index = hr->last_hc_index();
5927 hr->set_notHumongous();
5928 free_region(hr, &hr_pre_used, free_list, par);
5929
5930 uint i = hr->hrs_index() + 1;
5931 while (i < last_index) {
5932 HeapRegion* curr_hr = region_at(i);
5933 assert(curr_hr->continuesHumongous(), "invariant");
5934 curr_hr->set_notHumongous();
5935 free_region(curr_hr, &hr_pre_used, free_list, par);
5936 i += 1;
5937 }
5938 assert(hr_pre_used == hr_used,
5939 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5940 "should be the same", hr_pre_used, hr_used));
5941 *pre_used += hr_pre_used;
5942 }
5943
5944 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5945 FreeRegionList* free_list,
5946 OldRegionSet* old_proxy_set,
5947 HumongousRegionSet* humongous_proxy_set,
5948 bool par) {
5949 if (pre_used > 0) {
5950 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5951 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5952 assert(_summary_bytes_used >= pre_used,
5953 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5954 "should be >= pre_used: "SIZE_FORMAT,
5955 _summary_bytes_used, pre_used));
5956 _summary_bytes_used -= pre_used;
5957 }
5958 if (free_list != NULL && !free_list->is_empty()) {
5959 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5960 _free_list.add_as_head(free_list);
5961 }
5962 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5963 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5964 _old_set.update_from_proxy(old_proxy_set);
5965 }
5966 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5967 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5968 _humongous_set.update_from_proxy(humongous_proxy_set);
5969 }
5970 }
5971
5972 class G1ParCleanupCTTask : public AbstractGangTask {
5973 CardTableModRefBS* _ct_bs;
5974 G1CollectedHeap* _g1h;
5975 HeapRegion* volatile _su_head;
5976 public:
5977 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5978 G1CollectedHeap* g1h) :
5979 AbstractGangTask("G1 Par Cleanup CT Task"),
5980 _ct_bs(ct_bs), _g1h(g1h) { }
5981
5982 void work(uint worker_id) {
5983 HeapRegion* r;
5984 while (r = _g1h->pop_dirty_cards_region()) {
5985 clear_cards(r);
5986 }
5987 }
5988
5989 void clear_cards(HeapRegion* r) {
5990 // Cards of the survivors should have already been dirtied.
5991 if (!r->is_survivor()) {
5992 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5993 }
5994 }
5995 };
5996
5997 #ifndef PRODUCT
5998 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5999 G1CollectedHeap* _g1h;
6000 CardTableModRefBS* _ct_bs;
6001 public:
6002 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
6003 : _g1h(g1h), _ct_bs(ct_bs) { }
6004 virtual bool doHeapRegion(HeapRegion* r) {
6005 if (r->is_survivor()) {
6006 _g1h->verify_dirty_region(r);
6007 } else {
6008 _g1h->verify_not_dirty_region(r);
6009 }
6010 return false;
6011 }
6012 };
6013
6014 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6015 // All of the region should be clean.
6016 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
6017 MemRegion mr(hr->bottom(), hr->end());
6018 ct_bs->verify_not_dirty_region(mr);
6019 }
6020
6021 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6022 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6023 // dirty allocated blocks as they allocate them. The thread that
6024 // retires each region and replaces it with a new one will do a
6025 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6026 // not dirty that area (one less thing to have to do while holding
6027 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6028 // is dirty.
6029 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
6030 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6031 ct_bs->verify_dirty_region(mr);
6032 }
6033
6034 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6035 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
6036 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6037 verify_dirty_region(hr);
6038 }
6039 }
6040
6041 void G1CollectedHeap::verify_dirty_young_regions() {
6042 verify_dirty_young_list(_young_list->first_region());
6043 }
6044 #endif
6045
6046 void G1CollectedHeap::cleanUpCardTable() {
6047 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
6048 double start = os::elapsedTime();
6049
6050 {
6051 // Iterate over the dirty cards region list.
6052 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6053
6054 if (G1CollectedHeap::use_parallel_gc_threads()) {
6055 set_par_threads();
6056 workers()->run_task(&cleanup_task);
6057 set_par_threads(0);
6058 } else {
6059 while (_dirty_cards_region_list) {
6060 HeapRegion* r = _dirty_cards_region_list;
6061 cleanup_task.clear_cards(r);
6062 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6063 if (_dirty_cards_region_list == r) {
6064 // The last region.
6065 _dirty_cards_region_list = NULL;
6066 }
6067 r->set_next_dirty_cards_region(NULL);
6068 }
6069 }
6070 #ifndef PRODUCT
6071 if (G1VerifyCTCleanup || VerifyAfterGC) {
6072 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6073 heap_region_iterate(&cleanup_verifier);
6074 }
6075 #endif
6076 }
6077
6078 double elapsed = os::elapsedTime() - start;
6079 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6080 }
6081
6082 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6083 size_t pre_used = 0;
6084 FreeRegionList local_free_list("Local List for CSet Freeing");
6085
6086 double young_time_ms = 0.0;
6087 double non_young_time_ms = 0.0;
6088
6089 // Since the collection set is a superset of the the young list,
6090 // all we need to do to clear the young list is clear its
6091 // head and length, and unlink any young regions in the code below
6092 _young_list->clear();
6093
6094 G1CollectorPolicy* policy = g1_policy();
6095
6096 double start_sec = os::elapsedTime();
6097 bool non_young = true;
6098
6099 HeapRegion* cur = cs_head;
6100 int age_bound = -1;
6101 size_t rs_lengths = 0;
6102
6103 while (cur != NULL) {
6104 assert(!is_on_master_free_list(cur), "sanity");
6105 if (non_young) {
6106 if (cur->is_young()) {
6107 double end_sec = os::elapsedTime();
6108 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6109 non_young_time_ms += elapsed_ms;
6110
6111 start_sec = os::elapsedTime();
6112 non_young = false;
6113 }
6114 } else {
6115 if (!cur->is_young()) {
6116 double end_sec = os::elapsedTime();
6117 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6118 young_time_ms += elapsed_ms;
6119
6120 start_sec = os::elapsedTime();
6121 non_young = true;
6122 }
6123 }
6124
6125 rs_lengths += cur->rem_set()->occupied();
6126
6127 HeapRegion* next = cur->next_in_collection_set();
6128 assert(cur->in_collection_set(), "bad CS");
6129 cur->set_next_in_collection_set(NULL);
6130 cur->set_in_collection_set(false);
6131
6132 if (cur->is_young()) {
6133 int index = cur->young_index_in_cset();
6134 assert(index != -1, "invariant");
6135 assert((uint) index < policy->young_cset_region_length(), "invariant");
6136 size_t words_survived = _surviving_young_words[index];
6137 cur->record_surv_words_in_group(words_survived);
6138
6139 // At this point the we have 'popped' cur from the collection set
6140 // (linked via next_in_collection_set()) but it is still in the
6141 // young list (linked via next_young_region()). Clear the
6142 // _next_young_region field.
6143 cur->set_next_young_region(NULL);
6144 } else {
6145 int index = cur->young_index_in_cset();
6146 assert(index == -1, "invariant");
6147 }
6148
6149 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6150 (!cur->is_young() && cur->young_index_in_cset() == -1),
6151 "invariant" );
6152
6153 if (!cur->evacuation_failed()) {
6154 MemRegion used_mr = cur->used_region();
6155
6156 // And the region is empty.
6157 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6158 free_region(cur, &pre_used, &local_free_list, false /* par */);
6159 } else {
6160 cur->uninstall_surv_rate_group();
6161 if (cur->is_young()) {
6162 cur->set_young_index_in_cset(-1);
6163 }
6164 cur->set_not_young();
6165 cur->set_evacuation_failed(false);
6166 // The region is now considered to be old.
6167 _old_set.add(cur);
6168 evacuation_info.increment_collectionset_used_after(cur->used());
6169 }
6170 cur = next;
6171 }
6172
6173 evacuation_info.set_regions_freed(local_free_list.length());
6174 policy->record_max_rs_lengths(rs_lengths);
6175 policy->cset_regions_freed();
6176
6177 double end_sec = os::elapsedTime();
6178 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6179
6180 if (non_young) {
6181 non_young_time_ms += elapsed_ms;
6182 } else {
6183 young_time_ms += elapsed_ms;
6184 }
6185
6186 update_sets_after_freeing_regions(pre_used, &local_free_list,
6187 NULL /* old_proxy_set */,
6188 NULL /* humongous_proxy_set */,
6189 false /* par */);
6190 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6191 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6192 }
6193
6194 // This routine is similar to the above but does not record
6195 // any policy statistics or update free lists; we are abandoning
6196 // the current incremental collection set in preparation of a
6197 // full collection. After the full GC we will start to build up
6198 // the incremental collection set again.
6199 // This is only called when we're doing a full collection
6200 // and is immediately followed by the tearing down of the young list.
6201
6202 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6203 HeapRegion* cur = cs_head;
6204
6205 while (cur != NULL) {
6206 HeapRegion* next = cur->next_in_collection_set();
6207 assert(cur->in_collection_set(), "bad CS");
6208 cur->set_next_in_collection_set(NULL);
6209 cur->set_in_collection_set(false);
6210 cur->set_young_index_in_cset(-1);
6211 cur = next;
6212 }
6213 }
6214
6215 void G1CollectedHeap::set_free_regions_coming() {
6216 if (G1ConcRegionFreeingVerbose) {
6217 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6218 "setting free regions coming");
6219 }
6220
6221 assert(!free_regions_coming(), "pre-condition");
6222 _free_regions_coming = true;
6223 }
6224
6225 void G1CollectedHeap::reset_free_regions_coming() {
6226 assert(free_regions_coming(), "pre-condition");
6227
6228 {
6229 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6230 _free_regions_coming = false;
6231 SecondaryFreeList_lock->notify_all();
6232 }
6233
6234 if (G1ConcRegionFreeingVerbose) {
6235 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6236 "reset free regions coming");
6237 }
6238 }
6239
6240 void G1CollectedHeap::wait_while_free_regions_coming() {
6241 // Most of the time we won't have to wait, so let's do a quick test
6242 // first before we take the lock.
6243 if (!free_regions_coming()) {
6244 return;
6245 }
6246
6247 if (G1ConcRegionFreeingVerbose) {
6248 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6249 "waiting for free regions");
6250 }
6251
6252 {
6253 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6254 while (free_regions_coming()) {
6255 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6256 }
6257 }
6258
6259 if (G1ConcRegionFreeingVerbose) {
6260 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6261 "done waiting for free regions");
6262 }
6263 }
6264
6265 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6266 assert(heap_lock_held_for_gc(),
6267 "the heap lock should already be held by or for this thread");
6268 _young_list->push_region(hr);
6269 }
6270
6271 class NoYoungRegionsClosure: public HeapRegionClosure {
6272 private:
6273 bool _success;
6274 public:
6275 NoYoungRegionsClosure() : _success(true) { }
6276 bool doHeapRegion(HeapRegion* r) {
6277 if (r->is_young()) {
6278 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6279 r->bottom(), r->end());
6280 _success = false;
6281 }
6282 return false;
6283 }
6284 bool success() { return _success; }
6285 };
6286
6287 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6288 bool ret = _young_list->check_list_empty(check_sample);
6289
6290 if (check_heap) {
6291 NoYoungRegionsClosure closure;
6292 heap_region_iterate(&closure);
6293 ret = ret && closure.success();
6294 }
6295
6296 return ret;
6297 }
6298
6299 class TearDownRegionSetsClosure : public HeapRegionClosure {
6300 private:
6301 OldRegionSet *_old_set;
6302
6303 public:
6304 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6305
6306 bool doHeapRegion(HeapRegion* r) {
6307 if (r->is_empty()) {
6308 // We ignore empty regions, we'll empty the free list afterwards
6309 } else if (r->is_young()) {
6310 // We ignore young regions, we'll empty the young list afterwards
6311 } else if (r->isHumongous()) {
6312 // We ignore humongous regions, we're not tearing down the
6313 // humongous region set
6314 } else {
6315 // The rest should be old
6316 _old_set->remove(r);
6317 }
6318 return false;
6319 }
6320
6321 ~TearDownRegionSetsClosure() {
6322 assert(_old_set->is_empty(), "post-condition");
6323 }
6324 };
6325
6326 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6327 assert_at_safepoint(true /* should_be_vm_thread */);
6328
6329 if (!free_list_only) {
6330 TearDownRegionSetsClosure cl(&_old_set);
6331 heap_region_iterate(&cl);
6332
6333 // Need to do this after the heap iteration to be able to
6334 // recognize the young regions and ignore them during the iteration.
6335 _young_list->empty_list();
6336 }
6337 _free_list.remove_all();
6338 }
6339
6340 class RebuildRegionSetsClosure : public HeapRegionClosure {
6341 private:
6342 bool _free_list_only;
6343 OldRegionSet* _old_set;
6344 FreeRegionList* _free_list;
6345 size_t _total_used;
6346
6347 public:
6348 RebuildRegionSetsClosure(bool free_list_only,
6349 OldRegionSet* old_set, FreeRegionList* free_list) :
6350 _free_list_only(free_list_only),
6351 _old_set(old_set), _free_list(free_list), _total_used(0) {
6352 assert(_free_list->is_empty(), "pre-condition");
6353 if (!free_list_only) {
6354 assert(_old_set->is_empty(), "pre-condition");
6355 }
6356 }
6357
6358 bool doHeapRegion(HeapRegion* r) {
6359 if (r->continuesHumongous()) {
6360 return false;
6361 }
6362
6363 if (r->is_empty()) {
6364 // Add free regions to the free list
6365 _free_list->add_as_tail(r);
6366 } else if (!_free_list_only) {
6367 assert(!r->is_young(), "we should not come across young regions");
6368
6369 if (r->isHumongous()) {
6370 // We ignore humongous regions, we left the humongous set unchanged
6371 } else {
6372 // The rest should be old, add them to the old set
6373 _old_set->add(r);
6374 }
6375 _total_used += r->used();
6376 }
6377
6378 return false;
6379 }
6380
6381 size_t total_used() {
6382 return _total_used;
6383 }
6384 };
6385
6386 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6387 assert_at_safepoint(true /* should_be_vm_thread */);
6388
6389 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6390 heap_region_iterate(&cl);
6391
6392 if (!free_list_only) {
6393 _summary_bytes_used = cl.total_used();
6394 }
6395 assert(_summary_bytes_used == recalculate_used(),
6396 err_msg("inconsistent _summary_bytes_used, "
6397 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6398 _summary_bytes_used, recalculate_used()));
6399 }
6400
6401 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6402 _refine_cte_cl->set_concurrent(concurrent);
6403 }
6404
6405 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6406 HeapRegion* hr = heap_region_containing(p);
6407 if (hr == NULL) {
6408 return false;
6409 } else {
6410 return hr->is_in(p);
6411 }
6412 }
6413
6414 // Methods for the mutator alloc region
6415
6416 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6417 bool force) {
6418 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6419 assert(!force || g1_policy()->can_expand_young_list(),
6420 "if force is true we should be able to expand the young list");
6421 bool young_list_full = g1_policy()->is_young_list_full();
6422 if (force || !young_list_full) {
6423 HeapRegion* new_alloc_region = new_region(word_size,
6424 false /* do_expand */);
6425 if (new_alloc_region != NULL) {
6426 set_region_short_lived_locked(new_alloc_region);
6427 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6428 return new_alloc_region;
6429 }
6430 }
6431 return NULL;
6432 }
6433
6434 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6435 size_t allocated_bytes) {
6436 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6437 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6438
6439 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6440 _summary_bytes_used += allocated_bytes;
6441 _hr_printer.retire(alloc_region);
6442 // We update the eden sizes here, when the region is retired,
6443 // instead of when it's allocated, since this is the point that its
6444 // used space has been recored in _summary_bytes_used.
6445 g1mm()->update_eden_size();
6446 }
6447
6448 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6449 bool force) {
6450 return _g1h->new_mutator_alloc_region(word_size, force);
6451 }
6452
6453 void G1CollectedHeap::set_par_threads() {
6454 // Don't change the number of workers. Use the value previously set
6455 // in the workgroup.
6456 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6457 uint n_workers = workers()->active_workers();
6458 assert(UseDynamicNumberOfGCThreads ||
6459 n_workers == workers()->total_workers(),
6460 "Otherwise should be using the total number of workers");
6461 if (n_workers == 0) {
6462 assert(false, "Should have been set in prior evacuation pause.");
6463 n_workers = ParallelGCThreads;
6464 workers()->set_active_workers(n_workers);
6465 }
6466 set_par_threads(n_workers);
6467 }
6468
6469 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6470 size_t allocated_bytes) {
6471 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6472 }
6473
6474 // Methods for the GC alloc regions
6475
6476 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6477 uint count,
6478 GCAllocPurpose ap) {
6479 assert(FreeList_lock->owned_by_self(), "pre-condition");
6480
6481 if (count < g1_policy()->max_regions(ap)) {
6482 HeapRegion* new_alloc_region = new_region(word_size,
6483 true /* do_expand */);
6484 if (new_alloc_region != NULL) {
6485 // We really only need to do this for old regions given that we
6486 // should never scan survivors. But it doesn't hurt to do it
6487 // for survivors too.
6488 new_alloc_region->set_saved_mark();
6489 if (ap == GCAllocForSurvived) {
6490 new_alloc_region->set_survivor();
6491 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6492 } else {
6493 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6494 }
6495 bool during_im = g1_policy()->during_initial_mark_pause();
6496 new_alloc_region->note_start_of_copying(during_im);
6497 return new_alloc_region;
6498 } else {
6499 g1_policy()->note_alloc_region_limit_reached(ap);
6500 }
6501 }
6502 return NULL;
6503 }
6504
6505 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6506 size_t allocated_bytes,
6507 GCAllocPurpose ap) {
6508 bool during_im = g1_policy()->during_initial_mark_pause();
6509 alloc_region->note_end_of_copying(during_im);
6510 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6511 if (ap == GCAllocForSurvived) {
6512 young_list()->add_survivor_region(alloc_region);
6513 } else {
6514 _old_set.add(alloc_region);
6515 }
6516 _hr_printer.retire(alloc_region);
6517 }
6518
6519 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6520 bool force) {
6521 assert(!force, "not supported for GC alloc regions");
6522 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6523 }
6524
6525 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6526 size_t allocated_bytes) {
6527 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6528 GCAllocForSurvived);
6529 }
6530
6531 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6532 bool force) {
6533 assert(!force, "not supported for GC alloc regions");
6534 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6535 }
6536
6537 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6538 size_t allocated_bytes) {
6539 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6540 GCAllocForTenured);
6541 }
6542 // Heap region set verification
6543
6544 class VerifyRegionListsClosure : public HeapRegionClosure {
6545 private:
6546 FreeRegionList* _free_list;
6547 OldRegionSet* _old_set;
6548 HumongousRegionSet* _humongous_set;
6549 uint _region_count;
6550
6551 public:
6552 VerifyRegionListsClosure(OldRegionSet* old_set,
6553 HumongousRegionSet* humongous_set,
6554 FreeRegionList* free_list) :
6555 _old_set(old_set), _humongous_set(humongous_set),
6556 _free_list(free_list), _region_count(0) { }
6557
6558 uint region_count() { return _region_count; }
6559
6560 bool doHeapRegion(HeapRegion* hr) {
6561 _region_count += 1;
6562
6563 if (hr->continuesHumongous()) {
6564 return false;
6565 }
6566
6567 if (hr->is_young()) {
6568 // TODO
6569 } else if (hr->startsHumongous()) {
6570 _humongous_set->verify_next_region(hr);
6571 } else if (hr->is_empty()) {
6572 _free_list->verify_next_region(hr);
6573 } else {
6574 _old_set->verify_next_region(hr);
6575 }
6576 return false;
6577 }
6578 };
6579
6580 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6581 HeapWord* bottom) {
6582 HeapWord* end = bottom + HeapRegion::GrainWords;
6583 MemRegion mr(bottom, end);
6584 assert(_g1_reserved.contains(mr), "invariant");
6585 // This might return NULL if the allocation fails
6586 return new HeapRegion(hrs_index, _bot_shared, mr);
6587 }
6588
6589 void G1CollectedHeap::verify_region_sets() {
6590 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6591
6592 // First, check the explicit lists.
6593 _free_list.verify();
6594 {
6595 // Given that a concurrent operation might be adding regions to
6596 // the secondary free list we have to take the lock before
6597 // verifying it.
6598 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6599 _secondary_free_list.verify();
6600 }
6601 _old_set.verify();
6602 _humongous_set.verify();
6603
6604 // If a concurrent region freeing operation is in progress it will
6605 // be difficult to correctly attributed any free regions we come
6606 // across to the correct free list given that they might belong to
6607 // one of several (free_list, secondary_free_list, any local lists,
6608 // etc.). So, if that's the case we will skip the rest of the
6609 // verification operation. Alternatively, waiting for the concurrent
6610 // operation to complete will have a non-trivial effect on the GC's
6611 // operation (no concurrent operation will last longer than the
6612 // interval between two calls to verification) and it might hide
6613 // any issues that we would like to catch during testing.
6614 if (free_regions_coming()) {
6615 return;
6616 }
6617
6618 // Make sure we append the secondary_free_list on the free_list so
6619 // that all free regions we will come across can be safely
6620 // attributed to the free_list.
6621 append_secondary_free_list_if_not_empty_with_lock();
6622
6623 // Finally, make sure that the region accounting in the lists is
6624 // consistent with what we see in the heap.
6625 _old_set.verify_start();
6626 _humongous_set.verify_start();
6627 _free_list.verify_start();
6628
6629 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6630 heap_region_iterate(&cl);
6631
6632 _old_set.verify_end();
6633 _humongous_set.verify_end();
6634 _free_list.verify_end();
6635 }
6636
6637 // Optimized nmethod scanning
6638
6639 class RegisterNMethodOopClosure: public OopClosure {
6640 G1CollectedHeap* _g1h;
6641 nmethod* _nm;
6642
6643 template <class T> void do_oop_work(T* p) {
6644 T heap_oop = oopDesc::load_heap_oop(p);
6645 if (!oopDesc::is_null(heap_oop)) {
6646 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6647 HeapRegion* hr = _g1h->heap_region_containing(obj);
6648 assert(!hr->isHumongous(), "code root in humongous region?");
6649
6650 // HeapRegion::add_strong_code_root() avoids adding duplicate
6651 // entries but having duplicates is OK since we "mark" nmethods
6652 // as visited when we scan the strong code root lists during the GC.
6653 hr->add_strong_code_root(_nm);
6654 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), "add failed?");
6655 }
6656 }
6657
6658 public:
6659 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6660 _g1h(g1h), _nm(nm) {}
6661
6662 void do_oop(oop* p) { do_oop_work(p); }
6663 void do_oop(narrowOop* p) { do_oop_work(p); }
6664 };
6665
6666 class UnregisterNMethodOopClosure: public OopClosure {
6667 G1CollectedHeap* _g1h;
6668 nmethod* _nm;
6669
6670 template <class T> void do_oop_work(T* p) {
6671 T heap_oop = oopDesc::load_heap_oop(p);
6672 if (!oopDesc::is_null(heap_oop)) {
6673 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6674 HeapRegion* hr = _g1h->heap_region_containing(obj);
6675 assert(!hr->isHumongous(), "code root in humongous region?");
6676 hr->remove_strong_code_root(_nm);
6677 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), "remove failed?");
6678 }
6679 }
6680
6681 public:
6682 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6683 _g1h(g1h), _nm(nm) {}
6684
6685 void do_oop(oop* p) { do_oop_work(p); }
6686 void do_oop(narrowOop* p) { do_oop_work(p); }
6687 };
6688
6689 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6690 CollectedHeap::register_nmethod(nm);
6691
6692 guarantee(nm != NULL, "sanity");
6693 RegisterNMethodOopClosure reg_cl(this, nm);
6694 nm->oops_do(®_cl);
6695 }
6696
6697 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6698 CollectedHeap::unregister_nmethod(nm);
6699
6700 guarantee(nm != NULL, "sanity");
6701 UnregisterNMethodOopClosure reg_cl(this, nm);
6702 nm->oops_do(®_cl, true);
6703 }
6704
6705 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6706 public:
6707 bool doHeapRegion(HeapRegion *hr) {
6708 assert(!hr->isHumongous(), "humongous region in collection set?");
6709 hr->migrate_strong_code_roots();
6710 return false;
6711 }
6712 };
6713
6714 void G1CollectedHeap::migrate_strong_code_roots() {
6715 MigrateCodeRootsHeapRegionClosure cl;
6716 double migrate_start = os::elapsedTime();
6717 collection_set_iterate(&cl);
6718 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6719 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6720 }
6721
6722 // Mark all the code roots that point into regions *not* in the
6723 // collection set.
6724 //
6725 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6726 // walking the the code roots lists of regions not in the collection
6727 // set. Suppose we have an nmethod (M) that points to objects in two
6728 // separate regions - one in the collection set (R1) and one not (R2).
6729 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6730 // nmethod M when walking the code roots for R1. When we come to scan
6731 // the code roots for R2, we would see that M is already marked and it
6732 // would be skipped and the objects in R2 that are referenced from M
6733 // would not be evacuated.
6734
6735 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6736
6737 class MarkStrongCodeRootOopClosure: public OopClosure {
6738 ConcurrentMark* _cm;
6739 HeapRegion* _hr;
6740 uint _worker_id;
6741
6742 template <class T> void do_oop_work(T* p) {
6743 T heap_oop = oopDesc::load_heap_oop(p);
6744 if (!oopDesc::is_null(heap_oop)) {
6745 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6746 // Only mark objects in the region (which is assumed
6747 // to be not in the collection set).
6748 if (_hr->is_in(obj)) {
6749 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6750 }
6751 }
6752 }
6753
6754 public:
6755 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6756 _cm(cm), _hr(hr), _worker_id(worker_id) {
6757 assert(!_hr->in_collection_set(), "sanity");
6758 }
6759
6760 void do_oop(narrowOop* p) { do_oop_work(p); }
6761 void do_oop(oop* p) { do_oop_work(p); }
6762 };
6763
6764 MarkStrongCodeRootOopClosure _oop_cl;
6765
6766 public:
6767 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6768 _oop_cl(cm, hr, worker_id) {}
6769
6770 void do_code_blob(CodeBlob* cb) {
6771 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6772 if (nm != NULL) {
6773 nm->oops_do(&_oop_cl);
6774 }
6775 }
6776 };
6777
6778 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6779 G1CollectedHeap* _g1h;
6780 uint _worker_id;
6781
6782 public:
6783 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6784 _g1h(g1h), _worker_id(worker_id) {}
6785
6786 bool doHeapRegion(HeapRegion *hr) {
6787 HeapRegionRemSet* hrrs = hr->rem_set();
6788 if (hr->isHumongous()) {
6789 // Code roots should never be attached to a humongous region
6790 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
6791 return false;
6792 }
6793
6794 if (hr->in_collection_set()) {
6795 // Don't mark code roots into regions in the collection set here.
6796 // They will be marked when we scan them.
6797 return false;
6798 }
6799
6800 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6801 hr->strong_code_roots_do(&cb_cl);
6802 return false;
6803 }
6804 };
6805
6806 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6807 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6808 if (G1CollectedHeap::use_parallel_gc_threads()) {
6809 heap_region_par_iterate_chunked(&cl,
6810 worker_id,
6811 workers()->active_workers(),
6812 HeapRegion::ParMarkRootClaimValue);
6813 } else {
6814 heap_region_iterate(&cl);
6815 }
6816 }
6817
6818 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6819 G1CollectedHeap* _g1h;
6820
6821 public:
6822 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6823 _g1h(g1h) {}
6824
6825 void do_code_blob(CodeBlob* cb) {
6826 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6827 if (nm == NULL) {
6828 return;
6829 }
6830
6831 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6832 _g1h->register_nmethod(nm);
6833 }
6834 }
6835 };
6836
6837 void G1CollectedHeap::rebuild_strong_code_roots() {
6838 RebuildStrongCodeRootClosure blob_cl(this);
6839 CodeCache::blobs_do(&blob_cl);
6840 }