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 GCCause::_g1_inc_collection_pause);
986 if (result != NULL) {
987 assert(succeeded, "only way to get back a non-NULL result");
988 return result;
989 }
990
991 if (succeeded) {
992 // If we get here we successfully scheduled a collection which
993 // failed to allocate. No point in trying to allocate
994 // further. We'll just return NULL.
995 MutexLockerEx x(Heap_lock);
996 *gc_count_before_ret = total_collections();
997 return NULL;
998 }
999 } else {
1000 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1001 MutexLockerEx x(Heap_lock);
1002 *gc_count_before_ret = total_collections();
1003 return NULL;
1004 }
1005 // The GCLocker is either active or the GCLocker initiated
1006 // GC has not yet been performed. Stall until it is and
1007 // then retry the allocation.
1008 GC_locker::stall_until_clear();
1009 (*gclocker_retry_count_ret) += 1;
1010 }
1011
1012 // We can reach here if we were unsuccessful in scheduling a
1013 // collection (because another thread beat us to it) or if we were
1014 // stalled due to the GC locker. In either can we should retry the
1015 // allocation attempt in case another thread successfully
1016 // performed a collection and reclaimed enough space. We do the
1017 // first attempt (without holding the Heap_lock) here and the
1018 // follow-on attempt will be at the start of the next loop
1019 // iteration (after taking the Heap_lock).
1020 result = _mutator_alloc_region.attempt_allocation(word_size,
1021 false /* bot_updates */);
1022 if (result != NULL) {
1023 return result;
1024 }
1025
1026 // Give a warning if we seem to be looping forever.
1027 if ((QueuedAllocationWarningCount > 0) &&
1028 (try_count % QueuedAllocationWarningCount == 0)) {
1029 warning("G1CollectedHeap::attempt_allocation_slow() "
1030 "retries %d times", try_count);
1031 }
1032 }
1033
1034 ShouldNotReachHere();
1035 return NULL;
1036 }
1037
1038 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1039 unsigned int * gc_count_before_ret,
1040 int* gclocker_retry_count_ret) {
1041 // The structure of this method has a lot of similarities to
1042 // attempt_allocation_slow(). The reason these two were not merged
1043 // into a single one is that such a method would require several "if
1044 // allocation is not humongous do this, otherwise do that"
1045 // conditional paths which would obscure its flow. In fact, an early
1046 // version of this code did use a unified method which was harder to
1047 // follow and, as a result, it had subtle bugs that were hard to
1048 // track down. So keeping these two methods separate allows each to
1049 // be more readable. It will be good to keep these two in sync as
1050 // much as possible.
1051
1052 assert_heap_not_locked_and_not_at_safepoint();
1053 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1054 "should only be called for humongous allocations");
1055
1056 // Humongous objects can exhaust the heap quickly, so we should check if we
1057 // need to start a marking cycle at each humongous object allocation. We do
1058 // the check before we do the actual allocation. The reason for doing it
1059 // before the allocation is that we avoid having to keep track of the newly
1060 // allocated memory while we do a GC.
1061 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1062 word_size)) {
1063 collect(GCCause::_g1_humongous_allocation);
1064 }
1065
1066 // We will loop until a) we manage to successfully perform the
1067 // allocation or b) we successfully schedule a collection which
1068 // fails to perform the allocation. b) is the only case when we'll
1069 // return NULL.
1070 HeapWord* result = NULL;
1071 for (int try_count = 1; /* we'll return */; try_count += 1) {
1072 bool should_try_gc;
1073 unsigned int gc_count_before;
1074
1075 {
1076 MutexLockerEx x(Heap_lock);
1077
1078 // Given that humongous objects are not allocated in young
1079 // regions, we'll first try to do the allocation without doing a
1080 // collection hoping that there's enough space in the heap.
1081 result = humongous_obj_allocate(word_size);
1082 if (result != NULL) {
1083 return result;
1084 }
1085
1086 if (GC_locker::is_active_and_needs_gc()) {
1087 should_try_gc = false;
1088 } else {
1089 // The GCLocker may not be active but the GCLocker initiated
1090 // GC may not yet have been performed (GCLocker::needs_gc()
1091 // returns true). In this case we do not try this GC and
1092 // wait until the GCLocker initiated GC is performed, and
1093 // then retry the allocation.
1094 if (GC_locker::needs_gc()) {
1095 should_try_gc = false;
1096 } else {
1097 // Read the GC count while still holding the Heap_lock.
1098 gc_count_before = total_collections();
1099 should_try_gc = true;
1100 }
1101 }
1102 }
1103
1104 if (should_try_gc) {
1105 // If we failed to allocate the humongous object, we should try to
1106 // do a collection pause (if we're allowed) in case it reclaims
1107 // enough space for the allocation to succeed after the pause.
1108
1109 bool succeeded;
1110 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1111 GCCause::_g1_humongous_allocation);
1112 if (result != NULL) {
1113 assert(succeeded, "only way to get back a non-NULL result");
1114 return result;
1115 }
1116
1117 if (succeeded) {
1118 // If we get here we successfully scheduled a collection which
1119 // failed to allocate. No point in trying to allocate
1120 // further. We'll just return NULL.
1121 MutexLockerEx x(Heap_lock);
1122 *gc_count_before_ret = total_collections();
1123 return NULL;
1124 }
1125 } else {
1126 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1127 MutexLockerEx x(Heap_lock);
1128 *gc_count_before_ret = total_collections();
1129 return NULL;
1130 }
1131 // The GCLocker is either active or the GCLocker initiated
1132 // GC has not yet been performed. Stall until it is and
1133 // then retry the allocation.
1134 GC_locker::stall_until_clear();
1135 (*gclocker_retry_count_ret) += 1;
1136 }
1137
1138 // We can reach here if we were unsuccessful in scheduling a
1139 // collection (because another thread beat us to it) or if we were
1140 // stalled due to the GC locker. In either can we should retry the
1141 // allocation attempt in case another thread successfully
1142 // performed a collection and reclaimed enough space. Give a
1143 // warning if we seem to be looping forever.
1144
1145 if ((QueuedAllocationWarningCount > 0) &&
1146 (try_count % QueuedAllocationWarningCount == 0)) {
1147 warning("G1CollectedHeap::attempt_allocation_humongous() "
1148 "retries %d times", try_count);
1149 }
1150 }
1151
1152 ShouldNotReachHere();
1153 return NULL;
1154 }
1155
1156 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1157 bool expect_null_mutator_alloc_region) {
1158 assert_at_safepoint(true /* should_be_vm_thread */);
1159 assert(_mutator_alloc_region.get() == NULL ||
1160 !expect_null_mutator_alloc_region,
1161 "the current alloc region was unexpectedly found to be non-NULL");
1162
1163 if (!isHumongous(word_size)) {
1164 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1165 false /* bot_updates */);
1166 } else {
1167 HeapWord* result = humongous_obj_allocate(word_size);
1168 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1169 g1_policy()->set_initiate_conc_mark_if_possible();
1170 }
1171 return result;
1172 }
1173
1174 ShouldNotReachHere();
1175 }
1176
1177 class PostMCRemSetClearClosure: public HeapRegionClosure {
1178 G1CollectedHeap* _g1h;
1179 ModRefBarrierSet* _mr_bs;
1180 public:
1181 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1182 _g1h(g1h), _mr_bs(mr_bs) {}
1183
1184 bool doHeapRegion(HeapRegion* r) {
1185 HeapRegionRemSet* hrrs = r->rem_set();
1186
1187 if (r->continuesHumongous()) {
1188 // We'll assert that the strong code root list and RSet is empty
1189 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1190 assert(hrrs->occupied() == 0, "RSet should be empty");
1191 return false;
1192 }
1193
1194 _g1h->reset_gc_time_stamps(r);
1195 hrrs->clear();
1196 // You might think here that we could clear just the cards
1197 // corresponding to the used region. But no: if we leave a dirty card
1198 // in a region we might allocate into, then it would prevent that card
1199 // from being enqueued, and cause it to be missed.
1200 // Re: the performance cost: we shouldn't be doing full GC anyway!
1201 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1202
1203 return false;
1204 }
1205 };
1206
1207 void G1CollectedHeap::clear_rsets_post_compaction() {
1208 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1209 heap_region_iterate(&rs_clear);
1210 }
1211
1212 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1213 G1CollectedHeap* _g1h;
1214 UpdateRSOopClosure _cl;
1215 int _worker_i;
1216 public:
1217 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1218 _cl(g1->g1_rem_set(), worker_i),
1219 _worker_i(worker_i),
1220 _g1h(g1)
1221 { }
1222
1223 bool doHeapRegion(HeapRegion* r) {
1224 if (!r->continuesHumongous()) {
1225 _cl.set_from(r);
1226 r->oop_iterate(&_cl);
1227 }
1228 return false;
1229 }
1230 };
1231
1232 class ParRebuildRSTask: public AbstractGangTask {
1233 G1CollectedHeap* _g1;
1234 public:
1235 ParRebuildRSTask(G1CollectedHeap* g1)
1236 : AbstractGangTask("ParRebuildRSTask"),
1237 _g1(g1)
1238 { }
1239
1240 void work(uint worker_id) {
1241 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1242 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1243 _g1->workers()->active_workers(),
1244 HeapRegion::RebuildRSClaimValue);
1245 }
1246 };
1247
1248 class PostCompactionPrinterClosure: public HeapRegionClosure {
1249 private:
1250 G1HRPrinter* _hr_printer;
1251 public:
1252 bool doHeapRegion(HeapRegion* hr) {
1253 assert(!hr->is_young(), "not expecting to find young regions");
1254 // We only generate output for non-empty regions.
1255 if (!hr->is_empty()) {
1256 if (!hr->isHumongous()) {
1257 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1258 } else if (hr->startsHumongous()) {
1259 if (hr->region_num() == 1) {
1260 // single humongous region
1261 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1262 } else {
1263 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1264 }
1265 } else {
1266 assert(hr->continuesHumongous(), "only way to get here");
1267 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1268 }
1269 }
1270 return false;
1271 }
1272
1273 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1274 : _hr_printer(hr_printer) { }
1275 };
1276
1277 void G1CollectedHeap::print_hrs_post_compaction() {
1278 PostCompactionPrinterClosure cl(hr_printer());
1279 heap_region_iterate(&cl);
1280 }
1281
1282 bool G1CollectedHeap::do_collection(bool explicit_gc,
1283 bool clear_all_soft_refs,
1284 size_t word_size) {
1285 assert_at_safepoint(true /* should_be_vm_thread */);
1286
1287 if (GC_locker::check_active_before_gc()) {
1288 return false;
1289 }
1290
1291 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1292 gc_timer->register_gc_start(os::elapsed_counter());
1293
1294 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1295 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1296
1297 SvcGCMarker sgcm(SvcGCMarker::FULL);
1298 ResourceMark rm;
1299
1300 print_heap_before_gc();
1301 trace_heap_before_gc(gc_tracer);
1302
1303 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1304
1305 HRSPhaseSetter x(HRSPhaseFullGC);
1306 verify_region_sets_optional();
1307
1308 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1309 collector_policy()->should_clear_all_soft_refs();
1310
1311 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1312
1313 {
1314 IsGCActiveMark x;
1315
1316 // Timing
1317 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1318 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1319 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1320
1321 {
1322 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1323 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1324 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1325
1326 double start = os::elapsedTime();
1327 g1_policy()->record_full_collection_start();
1328
1329 // Note: When we have a more flexible GC logging framework that
1330 // allows us to add optional attributes to a GC log record we
1331 // could consider timing and reporting how long we wait in the
1332 // following two methods.
1333 wait_while_free_regions_coming();
1334 // If we start the compaction before the CM threads finish
1335 // scanning the root regions we might trip them over as we'll
1336 // be moving objects / updating references. So let's wait until
1337 // they are done. By telling them to abort, they should complete
1338 // early.
1339 _cm->root_regions()->abort();
1340 _cm->root_regions()->wait_until_scan_finished();
1341 append_secondary_free_list_if_not_empty_with_lock();
1342
1343 gc_prologue(true);
1344 increment_total_collections(true /* full gc */);
1345 increment_old_marking_cycles_started();
1346
1347 assert(used() == recalculate_used(), "Should be equal");
1348
1349 verify_before_gc();
1350
1351 pre_full_gc_dump(gc_timer);
1352
1353 COMPILER2_PRESENT(DerivedPointerTable::clear());
1354
1355 // Disable discovery and empty the discovered lists
1356 // for the CM ref processor.
1357 ref_processor_cm()->disable_discovery();
1358 ref_processor_cm()->abandon_partial_discovery();
1359 ref_processor_cm()->verify_no_references_recorded();
1360
1361 // Abandon current iterations of concurrent marking and concurrent
1362 // refinement, if any are in progress. We have to do this before
1363 // wait_until_scan_finished() below.
1364 concurrent_mark()->abort();
1365
1366 // Make sure we'll choose a new allocation region afterwards.
1367 release_mutator_alloc_region();
1368 abandon_gc_alloc_regions();
1369 g1_rem_set()->cleanupHRRS();
1370
1371 // We should call this after we retire any currently active alloc
1372 // regions so that all the ALLOC / RETIRE events are generated
1373 // before the start GC event.
1374 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1375
1376 // We may have added regions to the current incremental collection
1377 // set between the last GC or pause and now. We need to clear the
1378 // incremental collection set and then start rebuilding it afresh
1379 // after this full GC.
1380 abandon_collection_set(g1_policy()->inc_cset_head());
1381 g1_policy()->clear_incremental_cset();
1382 g1_policy()->stop_incremental_cset_building();
1383
1384 tear_down_region_sets(false /* free_list_only */);
1385 g1_policy()->set_gcs_are_young(true);
1386
1387 // See the comments in g1CollectedHeap.hpp and
1388 // G1CollectedHeap::ref_processing_init() about
1389 // how reference processing currently works in G1.
1390
1391 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1392 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1393
1394 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1395 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1396
1397 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1398 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1399
1400 // Do collection work
1401 {
1402 HandleMark hm; // Discard invalid handles created during gc
1403 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1404 }
1405
1406 assert(free_regions() == 0, "we should not have added any free regions");
1407 rebuild_region_sets(false /* free_list_only */);
1408
1409 // Enqueue any discovered reference objects that have
1410 // not been removed from the discovered lists.
1411 ref_processor_stw()->enqueue_discovered_references();
1412
1413 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1414
1415 MemoryService::track_memory_usage();
1416
1417 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1418 ref_processor_stw()->verify_no_references_recorded();
1419
1420 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1421 ClassLoaderDataGraph::purge();
1422 MetaspaceAux::verify_metrics();
1423
1424 // Note: since we've just done a full GC, concurrent
1425 // marking is no longer active. Therefore we need not
1426 // re-enable reference discovery for the CM ref processor.
1427 // That will be done at the start of the next marking cycle.
1428 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1429 ref_processor_cm()->verify_no_references_recorded();
1430
1431 reset_gc_time_stamp();
1432 // Since everything potentially moved, we will clear all remembered
1433 // sets, and clear all cards. Later we will rebuild remembered
1434 // sets. We will also reset the GC time stamps of the regions.
1435 clear_rsets_post_compaction();
1436 check_gc_time_stamps();
1437
1438 // Resize the heap if necessary.
1439 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1440
1441 if (_hr_printer.is_active()) {
1442 // We should do this after we potentially resize the heap so
1443 // that all the COMMIT / UNCOMMIT events are generated before
1444 // the end GC event.
1445
1446 print_hrs_post_compaction();
1447 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1448 }
1449
1450 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1451 if (hot_card_cache->use_cache()) {
1452 hot_card_cache->reset_card_counts();
1453 hot_card_cache->reset_hot_cache();
1454 }
1455
1456 // Rebuild remembered sets of all regions.
1457 if (G1CollectedHeap::use_parallel_gc_threads()) {
1458 uint n_workers =
1459 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1460 workers()->active_workers(),
1461 Threads::number_of_non_daemon_threads());
1462 assert(UseDynamicNumberOfGCThreads ||
1463 n_workers == workers()->total_workers(),
1464 "If not dynamic should be using all the workers");
1465 workers()->set_active_workers(n_workers);
1466 // Set parallel threads in the heap (_n_par_threads) only
1467 // before a parallel phase and always reset it to 0 after
1468 // the phase so that the number of parallel threads does
1469 // no get carried forward to a serial phase where there
1470 // may be code that is "possibly_parallel".
1471 set_par_threads(n_workers);
1472
1473 ParRebuildRSTask rebuild_rs_task(this);
1474 assert(check_heap_region_claim_values(
1475 HeapRegion::InitialClaimValue), "sanity check");
1476 assert(UseDynamicNumberOfGCThreads ||
1477 workers()->active_workers() == workers()->total_workers(),
1478 "Unless dynamic should use total workers");
1479 // Use the most recent number of active workers
1480 assert(workers()->active_workers() > 0,
1481 "Active workers not properly set");
1482 set_par_threads(workers()->active_workers());
1483 workers()->run_task(&rebuild_rs_task);
1484 set_par_threads(0);
1485 assert(check_heap_region_claim_values(
1486 HeapRegion::RebuildRSClaimValue), "sanity check");
1487 reset_heap_region_claim_values();
1488 } else {
1489 RebuildRSOutOfRegionClosure rebuild_rs(this);
1490 heap_region_iterate(&rebuild_rs);
1491 }
1492
1493 // Rebuild the strong code root lists for each region
1494 rebuild_strong_code_roots();
1495
1496 if (true) { // FIXME
1497 MetaspaceGC::compute_new_size();
1498 }
1499
1500 #ifdef TRACESPINNING
1501 ParallelTaskTerminator::print_termination_counts();
1502 #endif
1503
1504 // Discard all rset updates
1505 JavaThread::dirty_card_queue_set().abandon_logs();
1506 assert(!G1DeferredRSUpdate
1507 || (G1DeferredRSUpdate &&
1508 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1509
1510 _young_list->reset_sampled_info();
1511 // At this point there should be no regions in the
1512 // entire heap tagged as young.
1513 assert(check_young_list_empty(true /* check_heap */),
1514 "young list should be empty at this point");
1515
1516 // Update the number of full collections that have been completed.
1517 increment_old_marking_cycles_completed(false /* concurrent */);
1518
1519 _hrs.verify_optional();
1520 verify_region_sets_optional();
1521
1522 verify_after_gc();
1523
1524 // Start a new incremental collection set for the next pause
1525 assert(g1_policy()->collection_set() == NULL, "must be");
1526 g1_policy()->start_incremental_cset_building();
1527
1528 // Clear the _cset_fast_test bitmap in anticipation of adding
1529 // regions to the incremental collection set for the next
1530 // evacuation pause.
1531 clear_cset_fast_test();
1532
1533 init_mutator_alloc_region();
1534
1535 double end = os::elapsedTime();
1536 g1_policy()->record_full_collection_end();
1537
1538 if (G1Log::fine()) {
1539 g1_policy()->print_heap_transition();
1540 }
1541
1542 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1543 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1544 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1545 // before any GC notifications are raised.
1546 g1mm()->update_sizes();
1547
1548 gc_epilogue(true);
1549 }
1550
1551 if (G1Log::finer()) {
1552 g1_policy()->print_detailed_heap_transition(true /* full */);
1553 }
1554
1555 print_heap_after_gc();
1556 trace_heap_after_gc(gc_tracer);
1557
1558 post_full_gc_dump(gc_timer);
1559
1560 gc_timer->register_gc_end(os::elapsed_counter());
1561 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1562 }
1563
1564 return true;
1565 }
1566
1567 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1568 // do_collection() will return whether it succeeded in performing
1569 // the GC. Currently, there is no facility on the
1570 // do_full_collection() API to notify the caller than the collection
1571 // did not succeed (e.g., because it was locked out by the GC
1572 // locker). So, right now, we'll ignore the return value.
1573 bool dummy = do_collection(true, /* explicit_gc */
1574 clear_all_soft_refs,
1575 0 /* word_size */);
1576 }
1577
1578 // This code is mostly copied from TenuredGeneration.
1579 void
1580 G1CollectedHeap::
1581 resize_if_necessary_after_full_collection(size_t word_size) {
1582 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1583
1584 // Include the current allocation, if any, and bytes that will be
1585 // pre-allocated to support collections, as "used".
1586 const size_t used_after_gc = used();
1587 const size_t capacity_after_gc = capacity();
1588 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1589
1590 // This is enforced in arguments.cpp.
1591 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1592 "otherwise the code below doesn't make sense");
1593
1594 // We don't have floating point command-line arguments
1595 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1596 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1597 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1598 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1599
1600 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1601 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1602
1603 // We have to be careful here as these two calculations can overflow
1604 // 32-bit size_t's.
1605 double used_after_gc_d = (double) used_after_gc;
1606 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1607 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1608
1609 // Let's make sure that they are both under the max heap size, which
1610 // by default will make them fit into a size_t.
1611 double desired_capacity_upper_bound = (double) max_heap_size;
1612 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1613 desired_capacity_upper_bound);
1614 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1615 desired_capacity_upper_bound);
1616
1617 // We can now safely turn them into size_t's.
1618 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1619 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1620
1621 // This assert only makes sense here, before we adjust them
1622 // with respect to the min and max heap size.
1623 assert(minimum_desired_capacity <= maximum_desired_capacity,
1624 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1625 "maximum_desired_capacity = "SIZE_FORMAT,
1626 minimum_desired_capacity, maximum_desired_capacity));
1627
1628 // Should not be greater than the heap max size. No need to adjust
1629 // it with respect to the heap min size as it's a lower bound (i.e.,
1630 // we'll try to make the capacity larger than it, not smaller).
1631 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1632 // Should not be less than the heap min size. No need to adjust it
1633 // with respect to the heap max size as it's an upper bound (i.e.,
1634 // we'll try to make the capacity smaller than it, not greater).
1635 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1636
1637 if (capacity_after_gc < minimum_desired_capacity) {
1638 // Don't expand unless it's significant
1639 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1640 ergo_verbose4(ErgoHeapSizing,
1641 "attempt heap expansion",
1642 ergo_format_reason("capacity lower than "
1643 "min desired capacity after Full GC")
1644 ergo_format_byte("capacity")
1645 ergo_format_byte("occupancy")
1646 ergo_format_byte_perc("min desired capacity"),
1647 capacity_after_gc, used_after_gc,
1648 minimum_desired_capacity, (double) MinHeapFreeRatio);
1649 expand(expand_bytes);
1650
1651 // No expansion, now see if we want to shrink
1652 } else if (capacity_after_gc > maximum_desired_capacity) {
1653 // Capacity too large, compute shrinking size
1654 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1655 ergo_verbose4(ErgoHeapSizing,
1656 "attempt heap shrinking",
1657 ergo_format_reason("capacity higher than "
1658 "max desired capacity after Full GC")
1659 ergo_format_byte("capacity")
1660 ergo_format_byte("occupancy")
1661 ergo_format_byte_perc("max desired capacity"),
1662 capacity_after_gc, used_after_gc,
1663 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1664 shrink(shrink_bytes);
1665 }
1666 }
1667
1668
1669 HeapWord*
1670 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1671 bool* succeeded) {
1672 assert_at_safepoint(true /* should_be_vm_thread */);
1673
1674 *succeeded = true;
1675 // Let's attempt the allocation first.
1676 HeapWord* result =
1677 attempt_allocation_at_safepoint(word_size,
1678 false /* expect_null_mutator_alloc_region */);
1679 if (result != NULL) {
1680 assert(*succeeded, "sanity");
1681 return result;
1682 }
1683
1684 // In a G1 heap, we're supposed to keep allocation from failing by
1685 // incremental pauses. Therefore, at least for now, we'll favor
1686 // expansion over collection. (This might change in the future if we can
1687 // do something smarter than full collection to satisfy a failed alloc.)
1688 result = expand_and_allocate(word_size);
1689 if (result != NULL) {
1690 assert(*succeeded, "sanity");
1691 return result;
1692 }
1693
1694 // Expansion didn't work, we'll try to do a Full GC.
1695 bool gc_succeeded = do_collection(false, /* explicit_gc */
1696 false, /* clear_all_soft_refs */
1697 word_size);
1698 if (!gc_succeeded) {
1699 *succeeded = false;
1700 return NULL;
1701 }
1702
1703 // Retry the allocation
1704 result = attempt_allocation_at_safepoint(word_size,
1705 true /* expect_null_mutator_alloc_region */);
1706 if (result != NULL) {
1707 assert(*succeeded, "sanity");
1708 return result;
1709 }
1710
1711 // Then, try a Full GC that will collect all soft references.
1712 gc_succeeded = do_collection(false, /* explicit_gc */
1713 true, /* clear_all_soft_refs */
1714 word_size);
1715 if (!gc_succeeded) {
1716 *succeeded = false;
1717 return NULL;
1718 }
1719
1720 // Retry the allocation once more
1721 result = attempt_allocation_at_safepoint(word_size,
1722 true /* expect_null_mutator_alloc_region */);
1723 if (result != NULL) {
1724 assert(*succeeded, "sanity");
1725 return result;
1726 }
1727
1728 assert(!collector_policy()->should_clear_all_soft_refs(),
1729 "Flag should have been handled and cleared prior to this point");
1730
1731 // What else? We might try synchronous finalization later. If the total
1732 // space available is large enough for the allocation, then a more
1733 // complete compaction phase than we've tried so far might be
1734 // appropriate.
1735 assert(*succeeded, "sanity");
1736 return NULL;
1737 }
1738
1739 // Attempting to expand the heap sufficiently
1740 // to support an allocation of the given "word_size". If
1741 // successful, perform the allocation and return the address of the
1742 // allocated block, or else "NULL".
1743
1744 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1745 assert_at_safepoint(true /* should_be_vm_thread */);
1746
1747 verify_region_sets_optional();
1748
1749 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1750 ergo_verbose1(ErgoHeapSizing,
1751 "attempt heap expansion",
1752 ergo_format_reason("allocation request failed")
1753 ergo_format_byte("allocation request"),
1754 word_size * HeapWordSize);
1755 if (expand(expand_bytes)) {
1756 _hrs.verify_optional();
1757 verify_region_sets_optional();
1758 return attempt_allocation_at_safepoint(word_size,
1759 false /* expect_null_mutator_alloc_region */);
1760 }
1761 return NULL;
1762 }
1763
1764 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1765 HeapWord* new_end) {
1766 assert(old_end != new_end, "don't call this otherwise");
1767 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1768
1769 // Update the committed mem region.
1770 _g1_committed.set_end(new_end);
1771 // Tell the card table about the update.
1772 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1773 // Tell the BOT about the update.
1774 _bot_shared->resize(_g1_committed.word_size());
1775 // Tell the hot card cache about the update
1776 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1777 }
1778
1779 bool G1CollectedHeap::expand(size_t expand_bytes) {
1780 size_t old_mem_size = _g1_storage.committed_size();
1781 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1782 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1783 HeapRegion::GrainBytes);
1784 ergo_verbose2(ErgoHeapSizing,
1785 "expand the heap",
1786 ergo_format_byte("requested expansion amount")
1787 ergo_format_byte("attempted expansion amount"),
1788 expand_bytes, aligned_expand_bytes);
1789
1790 // First commit the memory.
1791 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1792 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1793 if (successful) {
1794 // Then propagate this update to the necessary data structures.
1795 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1796 update_committed_space(old_end, new_end);
1797
1798 FreeRegionList expansion_list("Local Expansion List");
1799 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1800 assert(mr.start() == old_end, "post-condition");
1801 // mr might be a smaller region than what was requested if
1802 // expand_by() was unable to allocate the HeapRegion instances
1803 assert(mr.end() <= new_end, "post-condition");
1804
1805 size_t actual_expand_bytes = mr.byte_size();
1806 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1807 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1808 "post-condition");
1809 if (actual_expand_bytes < aligned_expand_bytes) {
1810 // We could not expand _hrs to the desired size. In this case we
1811 // need to shrink the committed space accordingly.
1812 assert(mr.end() < new_end, "invariant");
1813
1814 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1815 // First uncommit the memory.
1816 _g1_storage.shrink_by(diff_bytes);
1817 // Then propagate this update to the necessary data structures.
1818 update_committed_space(new_end, mr.end());
1819 }
1820 _free_list.add_as_tail(&expansion_list);
1821
1822 if (_hr_printer.is_active()) {
1823 HeapWord* curr = mr.start();
1824 while (curr < mr.end()) {
1825 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1826 _hr_printer.commit(curr, curr_end);
1827 curr = curr_end;
1828 }
1829 assert(curr == mr.end(), "post-condition");
1830 }
1831 g1_policy()->record_new_heap_size(n_regions());
1832 } else {
1833 ergo_verbose0(ErgoHeapSizing,
1834 "did not expand the heap",
1835 ergo_format_reason("heap expansion operation failed"));
1836 // The expansion of the virtual storage space was unsuccessful.
1837 // Let's see if it was because we ran out of swap.
1838 if (G1ExitOnExpansionFailure &&
1839 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1840 // We had head room...
1841 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1842 }
1843 }
1844 return successful;
1845 }
1846
1847 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1848 size_t old_mem_size = _g1_storage.committed_size();
1849 size_t aligned_shrink_bytes =
1850 ReservedSpace::page_align_size_down(shrink_bytes);
1851 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1852 HeapRegion::GrainBytes);
1853 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1854
1855 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1856 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1857 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1858
1859 ergo_verbose3(ErgoHeapSizing,
1860 "shrink the heap",
1861 ergo_format_byte("requested shrinking amount")
1862 ergo_format_byte("aligned shrinking amount")
1863 ergo_format_byte("attempted shrinking amount"),
1864 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1865 if (num_regions_removed > 0) {
1866 _g1_storage.shrink_by(shrunk_bytes);
1867 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1868
1869 if (_hr_printer.is_active()) {
1870 HeapWord* curr = old_end;
1871 while (curr > new_end) {
1872 HeapWord* curr_end = curr;
1873 curr -= HeapRegion::GrainWords;
1874 _hr_printer.uncommit(curr, curr_end);
1875 }
1876 }
1877
1878 _expansion_regions += num_regions_removed;
1879 update_committed_space(old_end, new_end);
1880 HeapRegionRemSet::shrink_heap(n_regions());
1881 g1_policy()->record_new_heap_size(n_regions());
1882 } else {
1883 ergo_verbose0(ErgoHeapSizing,
1884 "did not shrink the heap",
1885 ergo_format_reason("heap shrinking operation failed"));
1886 }
1887 }
1888
1889 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1890 verify_region_sets_optional();
1891
1892 // We should only reach here at the end of a Full GC which means we
1893 // should not not be holding to any GC alloc regions. The method
1894 // below will make sure of that and do any remaining clean up.
1895 abandon_gc_alloc_regions();
1896
1897 // Instead of tearing down / rebuilding the free lists here, we
1898 // could instead use the remove_all_pending() method on free_list to
1899 // remove only the ones that we need to remove.
1900 tear_down_region_sets(true /* free_list_only */);
1901 shrink_helper(shrink_bytes);
1902 rebuild_region_sets(true /* free_list_only */);
1903
1904 _hrs.verify_optional();
1905 verify_region_sets_optional();
1906 }
1907
1908 // Public methods.
1909
1910 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1911 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1912 #endif // _MSC_VER
1913
1914
1915 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1916 SharedHeap(policy_),
1917 _g1_policy(policy_),
1918 _dirty_card_queue_set(false),
1919 _into_cset_dirty_card_queue_set(false),
1920 _is_alive_closure_cm(this),
1921 _is_alive_closure_stw(this),
1922 _ref_processor_cm(NULL),
1923 _ref_processor_stw(NULL),
1924 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1925 _bot_shared(NULL),
1926 _evac_failure_scan_stack(NULL),
1927 _mark_in_progress(false),
1928 _cg1r(NULL), _summary_bytes_used(0),
1929 _g1mm(NULL),
1930 _refine_cte_cl(NULL),
1931 _full_collection(false),
1932 _free_list("Master Free List"),
1933 _secondary_free_list("Secondary Free List"),
1934 _old_set("Old Set"),
1935 _humongous_set("Master Humongous Set"),
1936 _free_regions_coming(false),
1937 _young_list(new YoungList(this)),
1938 _gc_time_stamp(0),
1939 _retained_old_gc_alloc_region(NULL),
1940 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1941 _old_plab_stats(OldPLABSize, PLABWeight),
1942 _expand_heap_after_alloc_failure(true),
1943 _surviving_young_words(NULL),
1944 _old_marking_cycles_started(0),
1945 _old_marking_cycles_completed(0),
1946 _concurrent_cycle_started(false),
1947 _in_cset_fast_test(NULL),
1948 _in_cset_fast_test_base(NULL),
1949 _dirty_cards_region_list(NULL),
1950 _worker_cset_start_region(NULL),
1951 _worker_cset_start_region_time_stamp(NULL),
1952 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1953 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1954 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1955 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1956
1957 _g1h = this;
1958 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1959 vm_exit_during_initialization("Failed necessary allocation.");
1960 }
1961
1962 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1963
1964 int n_queues = MAX2((int)ParallelGCThreads, 1);
1965 _task_queues = new RefToScanQueueSet(n_queues);
1966
1967 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1968 assert(n_rem_sets > 0, "Invariant.");
1969
1970 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1971 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1972 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1973
1974 for (int i = 0; i < n_queues; i++) {
1975 RefToScanQueue* q = new RefToScanQueue();
1976 q->initialize();
1977 _task_queues->register_queue(i, q);
1978 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1979 }
1980 clear_cset_start_regions();
1981
1982 // Initialize the G1EvacuationFailureALot counters and flags.
1983 NOT_PRODUCT(reset_evacuation_should_fail();)
1984
1985 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1986 }
1987
1988 jint G1CollectedHeap::initialize() {
1989 CollectedHeap::pre_initialize();
1990 os::enable_vtime();
1991
1992 G1Log::init();
1993
1994 // Necessary to satisfy locking discipline assertions.
1995
1996 MutexLocker x(Heap_lock);
1997
1998 // We have to initialize the printer before committing the heap, as
1999 // it will be used then.
2000 _hr_printer.set_active(G1PrintHeapRegions);
2001
2002 // While there are no constraints in the GC code that HeapWordSize
2003 // be any particular value, there are multiple other areas in the
2004 // system which believe this to be true (e.g. oop->object_size in some
2005 // cases incorrectly returns the size in wordSize units rather than
2006 // HeapWordSize).
2007 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2008
2009 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2010 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2011
2012 // Ensure that the sizes are properly aligned.
2013 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2014 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "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 // Since max_byte_size is aligned to the size of a heap region (checked
2032 // above).
2033 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2034
2035 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2036 HeapRegion::GrainBytes);
2037
2038 // It is important to do this in a way such that concurrent readers can't
2039 // temporarily think something is in the heap. (I've actually seen this
2040 // happen in asserts: DLD.)
2041 _reserved.set_word_size(0);
2042 _reserved.set_start((HeapWord*)heap_rs.base());
2043 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2044
2045 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2046
2047 // Create the gen rem set (and barrier set) for the entire reserved region.
2048 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2049 set_barrier_set(rem_set()->bs());
2050 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2051 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2052 } else {
2053 vm_exit_during_initialization("G1 requires a mod ref bs.");
2054 return JNI_ENOMEM;
2055 }
2056
2057 // Also create a G1 rem set.
2058 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2059 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2060 } else {
2061 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2062 return JNI_ENOMEM;
2063 }
2064
2065 // Carve out the G1 part of the heap.
2066
2067 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2068 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2069 g1_rs.size()/HeapWordSize);
2070
2071 _g1_storage.initialize(g1_rs, 0);
2072 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2073 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2074 (HeapWord*) _g1_reserved.end(),
2075 _expansion_regions);
2076
2077 // Do later initialization work for concurrent refinement.
2078 _cg1r->init();
2079
2080 // 6843694 - ensure that the maximum region index can fit
2081 // in the remembered set structures.
2082 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2083 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2084
2085 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2086 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2087 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2088 "too many cards per region");
2089
2090 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2091
2092 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2093 heap_word_size(init_byte_size));
2094
2095 _g1h = this;
2096
2097 _in_cset_fast_test_length = max_regions();
2098 _in_cset_fast_test_base =
2099 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2100
2101 // We're biasing _in_cset_fast_test to avoid subtracting the
2102 // beginning of the heap every time we want to index; basically
2103 // it's the same with what we do with the card table.
2104 _in_cset_fast_test = _in_cset_fast_test_base -
2105 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2106
2107 // Clear the _cset_fast_test bitmap in anticipation of adding
2108 // regions to the incremental collection set for the first
2109 // evacuation pause.
2110 clear_cset_fast_test();
2111
2112 // Create the ConcurrentMark data structure and thread.
2113 // (Must do this late, so that "max_regions" is defined.)
2114 _cm = new ConcurrentMark(this, heap_rs);
2115 if (_cm == NULL || !_cm->completed_initialization()) {
2116 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2117 return JNI_ENOMEM;
2118 }
2119 _cmThread = _cm->cmThread();
2120
2121 // Initialize the from_card cache structure of HeapRegionRemSet.
2122 HeapRegionRemSet::init_heap(max_regions());
2123
2124 // Now expand into the initial heap size.
2125 if (!expand(init_byte_size)) {
2126 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2127 return JNI_ENOMEM;
2128 }
2129
2130 // Perform any initialization actions delegated to the policy.
2131 g1_policy()->init();
2132
2133 _refine_cte_cl =
2134 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2135 g1_rem_set(),
2136 concurrent_g1_refine());
2137 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2138
2139 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2140 SATB_Q_FL_lock,
2141 G1SATBProcessCompletedThreshold,
2142 Shared_SATB_Q_lock);
2143
2144 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2145 DirtyCardQ_FL_lock,
2146 concurrent_g1_refine()->yellow_zone(),
2147 concurrent_g1_refine()->red_zone(),
2148 Shared_DirtyCardQ_lock);
2149
2150 if (G1DeferredRSUpdate) {
2151 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2152 DirtyCardQ_FL_lock,
2153 -1, // never trigger processing
2154 -1, // no limit on length
2155 Shared_DirtyCardQ_lock,
2156 &JavaThread::dirty_card_queue_set());
2157 }
2158
2159 // Initialize the card queue set used to hold cards containing
2160 // references into the collection set.
2161 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2162 DirtyCardQ_FL_lock,
2163 -1, // never trigger processing
2164 -1, // no limit on length
2165 Shared_DirtyCardQ_lock,
2166 &JavaThread::dirty_card_queue_set());
2167
2168 // In case we're keeping closure specialization stats, initialize those
2169 // counts and that mechanism.
2170 SpecializationStats::clear();
2171
2172 // Here we allocate the dummy full region that is required by the
2173 // G1AllocRegion class. If we don't pass an address in the reserved
2174 // space here, lots of asserts fire.
2175
2176 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2177 _g1_reserved.start());
2178 // We'll re-use the same region whether the alloc region will
2179 // require BOT updates or not and, if it doesn't, then a non-young
2180 // region will complain that it cannot support allocations without
2181 // BOT updates. So we'll tag the dummy region as young to avoid that.
2182 dummy_region->set_young();
2183 // Make sure it's full.
2184 dummy_region->set_top(dummy_region->end());
2185 G1AllocRegion::setup(this, dummy_region);
2186
2187 init_mutator_alloc_region();
2188
2189 // Do create of the monitoring and management support so that
2190 // values in the heap have been properly initialized.
2191 _g1mm = new G1MonitoringSupport(this);
2192
2193 return JNI_OK;
2194 }
2195
2196 void G1CollectedHeap::ref_processing_init() {
2197 // Reference processing in G1 currently works as follows:
2198 //
2199 // * There are two reference processor instances. One is
2200 // used to record and process discovered references
2201 // during concurrent marking; the other is used to
2202 // record and process references during STW pauses
2203 // (both full and incremental).
2204 // * Both ref processors need to 'span' the entire heap as
2205 // the regions in the collection set may be dotted around.
2206 //
2207 // * For the concurrent marking ref processor:
2208 // * Reference discovery is enabled at initial marking.
2209 // * Reference discovery is disabled and the discovered
2210 // references processed etc during remarking.
2211 // * Reference discovery is MT (see below).
2212 // * Reference discovery requires a barrier (see below).
2213 // * Reference processing may or may not be MT
2214 // (depending on the value of ParallelRefProcEnabled
2215 // and ParallelGCThreads).
2216 // * A full GC disables reference discovery by the CM
2217 // ref processor and abandons any entries on it's
2218 // discovered lists.
2219 //
2220 // * For the STW processor:
2221 // * Non MT discovery is enabled at the start of a full GC.
2222 // * Processing and enqueueing during a full GC is non-MT.
2223 // * During a full GC, references are processed after marking.
2224 //
2225 // * Discovery (may or may not be MT) is enabled at the start
2226 // of an incremental evacuation pause.
2227 // * References are processed near the end of a STW evacuation pause.
2228 // * For both types of GC:
2229 // * Discovery is atomic - i.e. not concurrent.
2230 // * Reference discovery will not need a barrier.
2231
2232 SharedHeap::ref_processing_init();
2233 MemRegion mr = reserved_region();
2234
2235 // Concurrent Mark ref processor
2236 _ref_processor_cm =
2237 new ReferenceProcessor(mr, // span
2238 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2239 // mt processing
2240 (int) ParallelGCThreads,
2241 // degree of mt processing
2242 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2243 // mt discovery
2244 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2245 // degree of mt discovery
2246 false,
2247 // Reference discovery is not atomic
2248 &_is_alive_closure_cm,
2249 // is alive closure
2250 // (for efficiency/performance)
2251 true);
2252 // Setting next fields of discovered
2253 // lists requires a barrier.
2254
2255 // STW ref processor
2256 _ref_processor_stw =
2257 new ReferenceProcessor(mr, // span
2258 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2259 // mt processing
2260 MAX2((int)ParallelGCThreads, 1),
2261 // degree of mt processing
2262 (ParallelGCThreads > 1),
2263 // mt discovery
2264 MAX2((int)ParallelGCThreads, 1),
2265 // degree of mt discovery
2266 true,
2267 // Reference discovery is atomic
2268 &_is_alive_closure_stw,
2269 // is alive closure
2270 // (for efficiency/performance)
2271 false);
2272 // Setting next fields of discovered
2273 // lists requires a barrier.
2274 }
2275
2276 size_t G1CollectedHeap::capacity() const {
2277 return _g1_committed.byte_size();
2278 }
2279
2280 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2281 assert(!hr->continuesHumongous(), "pre-condition");
2282 hr->reset_gc_time_stamp();
2283 if (hr->startsHumongous()) {
2284 uint first_index = hr->hrs_index() + 1;
2285 uint last_index = hr->last_hc_index();
2286 for (uint i = first_index; i < last_index; i += 1) {
2287 HeapRegion* chr = region_at(i);
2288 assert(chr->continuesHumongous(), "sanity");
2289 chr->reset_gc_time_stamp();
2290 }
2291 }
2292 }
2293
2294 #ifndef PRODUCT
2295 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2296 private:
2297 unsigned _gc_time_stamp;
2298 bool _failures;
2299
2300 public:
2301 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2302 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2303
2304 virtual bool doHeapRegion(HeapRegion* hr) {
2305 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2306 if (_gc_time_stamp != region_gc_time_stamp) {
2307 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2308 "expected %d", HR_FORMAT_PARAMS(hr),
2309 region_gc_time_stamp, _gc_time_stamp);
2310 _failures = true;
2311 }
2312 return false;
2313 }
2314
2315 bool failures() { return _failures; }
2316 };
2317
2318 void G1CollectedHeap::check_gc_time_stamps() {
2319 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2320 heap_region_iterate(&cl);
2321 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2322 }
2323 #endif // PRODUCT
2324
2325 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2326 DirtyCardQueue* into_cset_dcq,
2327 bool concurrent,
2328 int worker_i) {
2329 // Clean cards in the hot card cache
2330 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2331 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2332
2333 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2334 int n_completed_buffers = 0;
2335 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2336 n_completed_buffers++;
2337 }
2338 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2339 dcqs.clear_n_completed_buffers();
2340 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2341 }
2342
2343
2344 // Computes the sum of the storage used by the various regions.
2345
2346 size_t G1CollectedHeap::used() const {
2347 assert(Heap_lock->owner() != NULL,
2348 "Should be owned on this thread's behalf.");
2349 size_t result = _summary_bytes_used;
2350 // Read only once in case it is set to NULL concurrently
2351 HeapRegion* hr = _mutator_alloc_region.get();
2352 if (hr != NULL)
2353 result += hr->used();
2354 return result;
2355 }
2356
2357 size_t G1CollectedHeap::used_unlocked() const {
2358 size_t result = _summary_bytes_used;
2359 return result;
2360 }
2361
2362 class SumUsedClosure: public HeapRegionClosure {
2363 size_t _used;
2364 public:
2365 SumUsedClosure() : _used(0) {}
2366 bool doHeapRegion(HeapRegion* r) {
2367 if (!r->continuesHumongous()) {
2368 _used += r->used();
2369 }
2370 return false;
2371 }
2372 size_t result() { return _used; }
2373 };
2374
2375 size_t G1CollectedHeap::recalculate_used() const {
2376 SumUsedClosure blk;
2377 heap_region_iterate(&blk);
2378 return blk.result();
2379 }
2380
2381 size_t G1CollectedHeap::unsafe_max_alloc() {
2382 if (free_regions() > 0) return HeapRegion::GrainBytes;
2383 // otherwise, is there space in the current allocation region?
2384
2385 // We need to store the current allocation region in a local variable
2386 // here. The problem is that this method doesn't take any locks and
2387 // there may be other threads which overwrite the current allocation
2388 // region field. attempt_allocation(), for example, sets it to NULL
2389 // and this can happen *after* the NULL check here but before the call
2390 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2391 // to be a problem in the optimized build, since the two loads of the
2392 // current allocation region field are optimized away.
2393 HeapRegion* hr = _mutator_alloc_region.get();
2394 if (hr == NULL) {
2395 return 0;
2396 }
2397 return hr->free();
2398 }
2399
2400 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2401 switch (cause) {
2402 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2403 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2404 case GCCause::_g1_humongous_allocation: return true;
2405 default: return false;
2406 }
2407 }
2408
2409 #ifndef PRODUCT
2410 void G1CollectedHeap::allocate_dummy_regions() {
2411 // Let's fill up most of the region
2412 size_t word_size = HeapRegion::GrainWords - 1024;
2413 // And as a result the region we'll allocate will be humongous.
2414 guarantee(isHumongous(word_size), "sanity");
2415
2416 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2417 // Let's use the existing mechanism for the allocation
2418 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2419 if (dummy_obj != NULL) {
2420 MemRegion mr(dummy_obj, word_size);
2421 CollectedHeap::fill_with_object(mr);
2422 } else {
2423 // If we can't allocate once, we probably cannot allocate
2424 // again. Let's get out of the loop.
2425 break;
2426 }
2427 }
2428 }
2429 #endif // !PRODUCT
2430
2431 void G1CollectedHeap::increment_old_marking_cycles_started() {
2432 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2433 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2434 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2435 _old_marking_cycles_started, _old_marking_cycles_completed));
2436
2437 _old_marking_cycles_started++;
2438 }
2439
2440 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2441 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2442
2443 // We assume that if concurrent == true, then the caller is a
2444 // concurrent thread that was joined the Suspendible Thread
2445 // Set. If there's ever a cheap way to check this, we should add an
2446 // assert here.
2447
2448 // Given that this method is called at the end of a Full GC or of a
2449 // concurrent cycle, and those can be nested (i.e., a Full GC can
2450 // interrupt a concurrent cycle), the number of full collections
2451 // completed should be either one (in the case where there was no
2452 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2453 // behind the number of full collections started.
2454
2455 // This is the case for the inner caller, i.e. a Full GC.
2456 assert(concurrent ||
2457 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2458 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2459 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2460 "is inconsistent with _old_marking_cycles_completed = %u",
2461 _old_marking_cycles_started, _old_marking_cycles_completed));
2462
2463 // This is the case for the outer caller, i.e. the concurrent cycle.
2464 assert(!concurrent ||
2465 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2466 err_msg("for outer caller (concurrent cycle): "
2467 "_old_marking_cycles_started = %u "
2468 "is inconsistent with _old_marking_cycles_completed = %u",
2469 _old_marking_cycles_started, _old_marking_cycles_completed));
2470
2471 _old_marking_cycles_completed += 1;
2472
2473 // We need to clear the "in_progress" flag in the CM thread before
2474 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2475 // is set) so that if a waiter requests another System.gc() it doesn't
2476 // incorrectly see that a marking cycle is still in progress.
2477 if (concurrent) {
2478 _cmThread->clear_in_progress();
2479 }
2480
2481 // This notify_all() will ensure that a thread that called
2482 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2483 // and it's waiting for a full GC to finish will be woken up. It is
2484 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2485 FullGCCount_lock->notify_all();
2486 }
2487
2488 void G1CollectedHeap::register_concurrent_cycle_start(jlong start_time) {
2489 _concurrent_cycle_started = true;
2490 _gc_timer_cm->register_gc_start(start_time);
2491
2492 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2493 trace_heap_before_gc(_gc_tracer_cm);
2494 }
2495
2496 void G1CollectedHeap::register_concurrent_cycle_end() {
2497 if (_concurrent_cycle_started) {
2498 _gc_timer_cm->register_gc_end(os::elapsed_counter());
2499
2500 if (_cm->has_aborted()) {
2501 _gc_tracer_cm->report_concurrent_mode_failure();
2502 }
2503 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2504
2505 _concurrent_cycle_started = false;
2506 }
2507 }
2508
2509 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2510 if (_concurrent_cycle_started) {
2511 trace_heap_after_gc(_gc_tracer_cm);
2512 }
2513 }
2514
2515 G1YCType G1CollectedHeap::yc_type() {
2516 bool is_young = g1_policy()->gcs_are_young();
2517 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2518 bool is_during_mark = mark_in_progress();
2519
2520 if (is_initial_mark) {
2521 return InitialMark;
2522 } else if (is_during_mark) {
2523 return DuringMark;
2524 } else if (is_young) {
2525 return Normal;
2526 } else {
2527 return Mixed;
2528 }
2529 }
2530
2531 void G1CollectedHeap::collect(GCCause::Cause cause) {
2532 assert_heap_not_locked();
2533
2534 unsigned int gc_count_before;
2535 unsigned int old_marking_count_before;
2536 bool retry_gc;
2537
2538 do {
2539 retry_gc = false;
2540
2541 {
2542 MutexLocker ml(Heap_lock);
2543
2544 // Read the GC count while holding the Heap_lock
2545 gc_count_before = total_collections();
2546 old_marking_count_before = _old_marking_cycles_started;
2547 }
2548
2549 if (should_do_concurrent_full_gc(cause)) {
2550 // Schedule an initial-mark evacuation pause that will start a
2551 // concurrent cycle. We're setting word_size to 0 which means that
2552 // we are not requesting a post-GC allocation.
2553 VM_G1IncCollectionPause op(gc_count_before,
2554 0, /* word_size */
2555 true, /* should_initiate_conc_mark */
2556 g1_policy()->max_pause_time_ms(),
2557 cause);
2558
2559 VMThread::execute(&op);
2560 if (!op.pause_succeeded()) {
2561 if (old_marking_count_before == _old_marking_cycles_started) {
2562 retry_gc = op.should_retry_gc();
2563 } else {
2564 // A Full GC happened while we were trying to schedule the
2565 // initial-mark GC. No point in starting a new cycle given
2566 // that the whole heap was collected anyway.
2567 }
2568
2569 if (retry_gc) {
2570 if (GC_locker::is_active_and_needs_gc()) {
2571 GC_locker::stall_until_clear();
2572 }
2573 }
2574 }
2575 } else {
2576 if (cause == GCCause::_gc_locker
2577 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2578
2579 // Schedule a standard evacuation pause. We're setting word_size
2580 // to 0 which means that we are not requesting a post-GC allocation.
2581 VM_G1IncCollectionPause op(gc_count_before,
2582 0, /* word_size */
2583 false, /* should_initiate_conc_mark */
2584 g1_policy()->max_pause_time_ms(),
2585 cause);
2586 VMThread::execute(&op);
2587 } else {
2588 // Schedule a Full GC.
2589 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2590 VMThread::execute(&op);
2591 }
2592 }
2593 } while (retry_gc);
2594 }
2595
2596 bool G1CollectedHeap::is_in(const void* p) const {
2597 if (_g1_committed.contains(p)) {
2598 // Given that we know that p is in the committed space,
2599 // heap_region_containing_raw() should successfully
2600 // return the containing region.
2601 HeapRegion* hr = heap_region_containing_raw(p);
2602 return hr->is_in(p);
2603 } else {
2604 return false;
2605 }
2606 }
2607
2608 // Iteration functions.
2609
2610 // Iterates an OopClosure over all ref-containing fields of objects
2611 // within a HeapRegion.
2612
2613 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2614 MemRegion _mr;
2615 ExtendedOopClosure* _cl;
2616 public:
2617 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2618 : _mr(mr), _cl(cl) {}
2619 bool doHeapRegion(HeapRegion* r) {
2620 if (!r->continuesHumongous()) {
2621 r->oop_iterate(_cl);
2622 }
2623 return false;
2624 }
2625 };
2626
2627 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2628 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2629 heap_region_iterate(&blk);
2630 }
2631
2632 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2633 IterateOopClosureRegionClosure blk(mr, cl);
2634 heap_region_iterate(&blk);
2635 }
2636
2637 // Iterates an ObjectClosure over all objects within a HeapRegion.
2638
2639 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2640 ObjectClosure* _cl;
2641 public:
2642 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2643 bool doHeapRegion(HeapRegion* r) {
2644 if (! r->continuesHumongous()) {
2645 r->object_iterate(_cl);
2646 }
2647 return false;
2648 }
2649 };
2650
2651 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2652 IterateObjectClosureRegionClosure blk(cl);
2653 heap_region_iterate(&blk);
2654 }
2655
2656 // Calls a SpaceClosure on a HeapRegion.
2657
2658 class SpaceClosureRegionClosure: public HeapRegionClosure {
2659 SpaceClosure* _cl;
2660 public:
2661 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2662 bool doHeapRegion(HeapRegion* r) {
2663 _cl->do_space(r);
2664 return false;
2665 }
2666 };
2667
2668 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2669 SpaceClosureRegionClosure blk(cl);
2670 heap_region_iterate(&blk);
2671 }
2672
2673 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2674 _hrs.iterate(cl);
2675 }
2676
2677 void
2678 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2679 uint worker_id,
2680 uint no_of_par_workers,
2681 jint claim_value) {
2682 const uint regions = n_regions();
2683 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2684 no_of_par_workers :
2685 1);
2686 assert(UseDynamicNumberOfGCThreads ||
2687 no_of_par_workers == workers()->total_workers(),
2688 "Non dynamic should use fixed number of workers");
2689 // try to spread out the starting points of the workers
2690 const HeapRegion* start_hr =
2691 start_region_for_worker(worker_id, no_of_par_workers);
2692 const uint start_index = start_hr->hrs_index();
2693
2694 // each worker will actually look at all regions
2695 for (uint count = 0; count < regions; ++count) {
2696 const uint index = (start_index + count) % regions;
2697 assert(0 <= index && index < regions, "sanity");
2698 HeapRegion* r = region_at(index);
2699 // we'll ignore "continues humongous" regions (we'll process them
2700 // when we come across their corresponding "start humongous"
2701 // region) and regions already claimed
2702 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2703 continue;
2704 }
2705 // OK, try to claim it
2706 if (r->claimHeapRegion(claim_value)) {
2707 // success!
2708 assert(!r->continuesHumongous(), "sanity");
2709 if (r->startsHumongous()) {
2710 // If the region is "starts humongous" we'll iterate over its
2711 // "continues humongous" first; in fact we'll do them
2712 // first. The order is important. In on case, calling the
2713 // closure on the "starts humongous" region might de-allocate
2714 // and clear all its "continues humongous" regions and, as a
2715 // result, we might end up processing them twice. So, we'll do
2716 // them first (notice: most closures will ignore them anyway) and
2717 // then we'll do the "starts humongous" region.
2718 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2719 HeapRegion* chr = region_at(ch_index);
2720
2721 // if the region has already been claimed or it's not
2722 // "continues humongous" we're done
2723 if (chr->claim_value() == claim_value ||
2724 !chr->continuesHumongous()) {
2725 break;
2726 }
2727
2728 // No one should have claimed it directly. We can given
2729 // that we claimed its "starts humongous" region.
2730 assert(chr->claim_value() != claim_value, "sanity");
2731 assert(chr->humongous_start_region() == r, "sanity");
2732
2733 if (chr->claimHeapRegion(claim_value)) {
2734 // we should always be able to claim it; no one else should
2735 // be trying to claim this region
2736
2737 bool res2 = cl->doHeapRegion(chr);
2738 assert(!res2, "Should not abort");
2739
2740 // Right now, this holds (i.e., no closure that actually
2741 // does something with "continues humongous" regions
2742 // clears them). We might have to weaken it in the future,
2743 // but let's leave these two asserts here for extra safety.
2744 assert(chr->continuesHumongous(), "should still be the case");
2745 assert(chr->humongous_start_region() == r, "sanity");
2746 } else {
2747 guarantee(false, "we should not reach here");
2748 }
2749 }
2750 }
2751
2752 assert(!r->continuesHumongous(), "sanity");
2753 bool res = cl->doHeapRegion(r);
2754 assert(!res, "Should not abort");
2755 }
2756 }
2757 }
2758
2759 class ResetClaimValuesClosure: public HeapRegionClosure {
2760 public:
2761 bool doHeapRegion(HeapRegion* r) {
2762 r->set_claim_value(HeapRegion::InitialClaimValue);
2763 return false;
2764 }
2765 };
2766
2767 void G1CollectedHeap::reset_heap_region_claim_values() {
2768 ResetClaimValuesClosure blk;
2769 heap_region_iterate(&blk);
2770 }
2771
2772 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2773 ResetClaimValuesClosure blk;
2774 collection_set_iterate(&blk);
2775 }
2776
2777 #ifdef ASSERT
2778 // This checks whether all regions in the heap have the correct claim
2779 // value. I also piggy-backed on this a check to ensure that the
2780 // humongous_start_region() information on "continues humongous"
2781 // regions is correct.
2782
2783 class CheckClaimValuesClosure : public HeapRegionClosure {
2784 private:
2785 jint _claim_value;
2786 uint _failures;
2787 HeapRegion* _sh_region;
2788
2789 public:
2790 CheckClaimValuesClosure(jint claim_value) :
2791 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2792 bool doHeapRegion(HeapRegion* r) {
2793 if (r->claim_value() != _claim_value) {
2794 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2795 "claim value = %d, should be %d",
2796 HR_FORMAT_PARAMS(r),
2797 r->claim_value(), _claim_value);
2798 ++_failures;
2799 }
2800 if (!r->isHumongous()) {
2801 _sh_region = NULL;
2802 } else if (r->startsHumongous()) {
2803 _sh_region = r;
2804 } else if (r->continuesHumongous()) {
2805 if (r->humongous_start_region() != _sh_region) {
2806 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2807 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2808 HR_FORMAT_PARAMS(r),
2809 r->humongous_start_region(),
2810 _sh_region);
2811 ++_failures;
2812 }
2813 }
2814 return false;
2815 }
2816 uint failures() { return _failures; }
2817 };
2818
2819 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2820 CheckClaimValuesClosure cl(claim_value);
2821 heap_region_iterate(&cl);
2822 return cl.failures() == 0;
2823 }
2824
2825 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2826 private:
2827 jint _claim_value;
2828 uint _failures;
2829
2830 public:
2831 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2832 _claim_value(claim_value), _failures(0) { }
2833
2834 uint failures() { return _failures; }
2835
2836 bool doHeapRegion(HeapRegion* hr) {
2837 assert(hr->in_collection_set(), "how?");
2838 assert(!hr->isHumongous(), "H-region in CSet");
2839 if (hr->claim_value() != _claim_value) {
2840 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2841 "claim value = %d, should be %d",
2842 HR_FORMAT_PARAMS(hr),
2843 hr->claim_value(), _claim_value);
2844 _failures += 1;
2845 }
2846 return false;
2847 }
2848 };
2849
2850 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2851 CheckClaimValuesInCSetHRClosure cl(claim_value);
2852 collection_set_iterate(&cl);
2853 return cl.failures() == 0;
2854 }
2855 #endif // ASSERT
2856
2857 // Clear the cached CSet starting regions and (more importantly)
2858 // the time stamps. Called when we reset the GC time stamp.
2859 void G1CollectedHeap::clear_cset_start_regions() {
2860 assert(_worker_cset_start_region != NULL, "sanity");
2861 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2862
2863 int n_queues = MAX2((int)ParallelGCThreads, 1);
2864 for (int i = 0; i < n_queues; i++) {
2865 _worker_cset_start_region[i] = NULL;
2866 _worker_cset_start_region_time_stamp[i] = 0;
2867 }
2868 }
2869
2870 // Given the id of a worker, obtain or calculate a suitable
2871 // starting region for iterating over the current collection set.
2872 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2873 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2874
2875 HeapRegion* result = NULL;
2876 unsigned gc_time_stamp = get_gc_time_stamp();
2877
2878 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2879 // Cached starting region for current worker was set
2880 // during the current pause - so it's valid.
2881 // Note: the cached starting heap region may be NULL
2882 // (when the collection set is empty).
2883 result = _worker_cset_start_region[worker_i];
2884 assert(result == NULL || result->in_collection_set(), "sanity");
2885 return result;
2886 }
2887
2888 // The cached entry was not valid so let's calculate
2889 // a suitable starting heap region for this worker.
2890
2891 // We want the parallel threads to start their collection
2892 // set iteration at different collection set regions to
2893 // avoid contention.
2894 // If we have:
2895 // n collection set regions
2896 // p threads
2897 // Then thread t will start at region floor ((t * n) / p)
2898
2899 result = g1_policy()->collection_set();
2900 if (G1CollectedHeap::use_parallel_gc_threads()) {
2901 uint cs_size = g1_policy()->cset_region_length();
2902 uint active_workers = workers()->active_workers();
2903 assert(UseDynamicNumberOfGCThreads ||
2904 active_workers == workers()->total_workers(),
2905 "Unless dynamic should use total workers");
2906
2907 uint end_ind = (cs_size * worker_i) / active_workers;
2908 uint start_ind = 0;
2909
2910 if (worker_i > 0 &&
2911 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2912 // Previous workers starting region is valid
2913 // so let's iterate from there
2914 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2915 result = _worker_cset_start_region[worker_i - 1];
2916 }
2917
2918 for (uint i = start_ind; i < end_ind; i++) {
2919 result = result->next_in_collection_set();
2920 }
2921 }
2922
2923 // Note: the calculated starting heap region may be NULL
2924 // (when the collection set is empty).
2925 assert(result == NULL || result->in_collection_set(), "sanity");
2926 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2927 "should be updated only once per pause");
2928 _worker_cset_start_region[worker_i] = result;
2929 OrderAccess::storestore();
2930 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2931 return result;
2932 }
2933
2934 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2935 uint no_of_par_workers) {
2936 uint worker_num =
2937 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2938 assert(UseDynamicNumberOfGCThreads ||
2939 no_of_par_workers == workers()->total_workers(),
2940 "Non dynamic should use fixed number of workers");
2941 const uint start_index = n_regions() * worker_i / worker_num;
2942 return region_at(start_index);
2943 }
2944
2945 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2946 HeapRegion* r = g1_policy()->collection_set();
2947 while (r != NULL) {
2948 HeapRegion* next = r->next_in_collection_set();
2949 if (cl->doHeapRegion(r)) {
2950 cl->incomplete();
2951 return;
2952 }
2953 r = next;
2954 }
2955 }
2956
2957 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2958 HeapRegionClosure *cl) {
2959 if (r == NULL) {
2960 // The CSet is empty so there's nothing to do.
2961 return;
2962 }
2963
2964 assert(r->in_collection_set(),
2965 "Start region must be a member of the collection set.");
2966 HeapRegion* cur = r;
2967 while (cur != NULL) {
2968 HeapRegion* next = cur->next_in_collection_set();
2969 if (cl->doHeapRegion(cur) && false) {
2970 cl->incomplete();
2971 return;
2972 }
2973 cur = next;
2974 }
2975 cur = g1_policy()->collection_set();
2976 while (cur != r) {
2977 HeapRegion* next = cur->next_in_collection_set();
2978 if (cl->doHeapRegion(cur) && false) {
2979 cl->incomplete();
2980 return;
2981 }
2982 cur = next;
2983 }
2984 }
2985
2986 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2987 return n_regions() > 0 ? region_at(0) : NULL;
2988 }
2989
2990
2991 Space* G1CollectedHeap::space_containing(const void* addr) const {
2992 Space* res = heap_region_containing(addr);
2993 return res;
2994 }
2995
2996 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2997 Space* sp = space_containing(addr);
2998 if (sp != NULL) {
2999 return sp->block_start(addr);
3000 }
3001 return NULL;
3002 }
3003
3004 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3005 Space* sp = space_containing(addr);
3006 assert(sp != NULL, "block_size of address outside of heap");
3007 return sp->block_size(addr);
3008 }
3009
3010 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3011 Space* sp = space_containing(addr);
3012 return sp->block_is_obj(addr);
3013 }
3014
3015 bool G1CollectedHeap::supports_tlab_allocation() const {
3016 return true;
3017 }
3018
3019 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3020 return HeapRegion::GrainBytes;
3021 }
3022
3023 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3024 // Return the remaining space in the cur alloc region, but not less than
3025 // the min TLAB size.
3026
3027 // Also, this value can be at most the humongous object threshold,
3028 // since we can't allow tlabs to grow big enough to accommodate
3029 // humongous objects.
3030
3031 HeapRegion* hr = _mutator_alloc_region.get();
3032 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3033 if (hr == NULL) {
3034 return max_tlab_size;
3035 } else {
3036 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3037 }
3038 }
3039
3040 size_t G1CollectedHeap::max_capacity() const {
3041 return _g1_reserved.byte_size();
3042 }
3043
3044 jlong G1CollectedHeap::millis_since_last_gc() {
3045 // assert(false, "NYI");
3046 return 0;
3047 }
3048
3049 void G1CollectedHeap::prepare_for_verify() {
3050 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3051 ensure_parsability(false);
3052 }
3053 g1_rem_set()->prepare_for_verify();
3054 }
3055
3056 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3057 VerifyOption vo) {
3058 switch (vo) {
3059 case VerifyOption_G1UsePrevMarking:
3060 return hr->obj_allocated_since_prev_marking(obj);
3061 case VerifyOption_G1UseNextMarking:
3062 return hr->obj_allocated_since_next_marking(obj);
3063 case VerifyOption_G1UseMarkWord:
3064 return false;
3065 default:
3066 ShouldNotReachHere();
3067 }
3068 return false; // keep some compilers happy
3069 }
3070
3071 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3072 switch (vo) {
3073 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3074 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3075 case VerifyOption_G1UseMarkWord: return NULL;
3076 default: ShouldNotReachHere();
3077 }
3078 return NULL; // keep some compilers happy
3079 }
3080
3081 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3082 switch (vo) {
3083 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3084 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3085 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3086 default: ShouldNotReachHere();
3087 }
3088 return false; // keep some compilers happy
3089 }
3090
3091 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3092 switch (vo) {
3093 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3094 case VerifyOption_G1UseNextMarking: return "NTAMS";
3095 case VerifyOption_G1UseMarkWord: return "NONE";
3096 default: ShouldNotReachHere();
3097 }
3098 return NULL; // keep some compilers happy
3099 }
3100
3101 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3102 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3103 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3104 // we can change this closure to extend the simpler OopClosure.
3105 class VerifyRootsClosure: public OopsInGenClosure {
3106 private:
3107 G1CollectedHeap* _g1h;
3108 VerifyOption _vo;
3109 bool _failures;
3110 public:
3111 // _vo == UsePrevMarking -> use "prev" marking information,
3112 // _vo == UseNextMarking -> use "next" marking information,
3113 // _vo == UseMarkWord -> use mark word from object header.
3114 VerifyRootsClosure(VerifyOption vo) :
3115 _g1h(G1CollectedHeap::heap()),
3116 _vo(vo),
3117 _failures(false) { }
3118
3119 bool failures() { return _failures; }
3120
3121 template <class T> void do_oop_nv(T* p) {
3122 T heap_oop = oopDesc::load_heap_oop(p);
3123 if (!oopDesc::is_null(heap_oop)) {
3124 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3125 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3126 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3127 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3128 if (_vo == VerifyOption_G1UseMarkWord) {
3129 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3130 }
3131 obj->print_on(gclog_or_tty);
3132 _failures = true;
3133 }
3134 }
3135 }
3136
3137 void do_oop(oop* p) { do_oop_nv(p); }
3138 void do_oop(narrowOop* p) { do_oop_nv(p); }
3139 };
3140
3141 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3142 G1CollectedHeap* _g1h;
3143 OopClosure* _root_cl;
3144 nmethod* _nm;
3145 VerifyOption _vo;
3146 bool _failures;
3147
3148 template <class T> void do_oop_work(T* p) {
3149 // First verify that this root is live
3150 _root_cl->do_oop(p);
3151
3152 if (!G1VerifyHeapRegionCodeRoots) {
3153 // We're not verifying the code roots attached to heap region.
3154 return;
3155 }
3156
3157 // Don't check the code roots during marking verification in a full GC
3158 if (_vo == VerifyOption_G1UseMarkWord) {
3159 return;
3160 }
3161
3162 // Now verify that the current nmethod (which contains p) is
3163 // in the code root list of the heap region containing the
3164 // object referenced by p.
3165
3166 T heap_oop = oopDesc::load_heap_oop(p);
3167 if (!oopDesc::is_null(heap_oop)) {
3168 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3169
3170 // Now fetch the region containing the object
3171 HeapRegion* hr = _g1h->heap_region_containing(obj);
3172 HeapRegionRemSet* hrrs = hr->rem_set();
3173 // Verify that the strong code root list for this region
3174 // contains the nmethod
3175 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3176 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3177 "from nmethod "PTR_FORMAT" not in strong "
3178 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3179 p, _nm, hr->bottom(), hr->end());
3180 _failures = true;
3181 }
3182 }
3183 }
3184
3185 public:
3186 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3187 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3188
3189 void do_oop(oop* p) { do_oop_work(p); }
3190 void do_oop(narrowOop* p) { do_oop_work(p); }
3191
3192 void set_nmethod(nmethod* nm) { _nm = nm; }
3193 bool failures() { return _failures; }
3194 };
3195
3196 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3197 G1VerifyCodeRootOopClosure* _oop_cl;
3198
3199 public:
3200 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3201 _oop_cl(oop_cl) {}
3202
3203 void do_code_blob(CodeBlob* cb) {
3204 nmethod* nm = cb->as_nmethod_or_null();
3205 if (nm != NULL) {
3206 _oop_cl->set_nmethod(nm);
3207 nm->oops_do(_oop_cl);
3208 }
3209 }
3210 };
3211
3212 class YoungRefCounterClosure : public OopClosure {
3213 G1CollectedHeap* _g1h;
3214 int _count;
3215 public:
3216 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3217 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3218 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3219
3220 int count() { return _count; }
3221 void reset_count() { _count = 0; };
3222 };
3223
3224 class VerifyKlassClosure: public KlassClosure {
3225 YoungRefCounterClosure _young_ref_counter_closure;
3226 OopClosure *_oop_closure;
3227 public:
3228 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3229 void do_klass(Klass* k) {
3230 k->oops_do(_oop_closure);
3231
3232 _young_ref_counter_closure.reset_count();
3233 k->oops_do(&_young_ref_counter_closure);
3234 if (_young_ref_counter_closure.count() > 0) {
3235 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3236 }
3237 }
3238 };
3239
3240 class VerifyLivenessOopClosure: public OopClosure {
3241 G1CollectedHeap* _g1h;
3242 VerifyOption _vo;
3243 public:
3244 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3245 _g1h(g1h), _vo(vo)
3246 { }
3247 void do_oop(narrowOop *p) { do_oop_work(p); }
3248 void do_oop( oop *p) { do_oop_work(p); }
3249
3250 template <class T> void do_oop_work(T *p) {
3251 oop obj = oopDesc::load_decode_heap_oop(p);
3252 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3253 "Dead object referenced by a not dead object");
3254 }
3255 };
3256
3257 class VerifyObjsInRegionClosure: public ObjectClosure {
3258 private:
3259 G1CollectedHeap* _g1h;
3260 size_t _live_bytes;
3261 HeapRegion *_hr;
3262 VerifyOption _vo;
3263 public:
3264 // _vo == UsePrevMarking -> use "prev" marking information,
3265 // _vo == UseNextMarking -> use "next" marking information,
3266 // _vo == UseMarkWord -> use mark word from object header.
3267 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3268 : _live_bytes(0), _hr(hr), _vo(vo) {
3269 _g1h = G1CollectedHeap::heap();
3270 }
3271 void do_object(oop o) {
3272 VerifyLivenessOopClosure isLive(_g1h, _vo);
3273 assert(o != NULL, "Huh?");
3274 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3275 // If the object is alive according to the mark word,
3276 // then verify that the marking information agrees.
3277 // Note we can't verify the contra-positive of the
3278 // above: if the object is dead (according to the mark
3279 // word), it may not be marked, or may have been marked
3280 // but has since became dead, or may have been allocated
3281 // since the last marking.
3282 if (_vo == VerifyOption_G1UseMarkWord) {
3283 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3284 }
3285
3286 o->oop_iterate_no_header(&isLive);
3287 if (!_hr->obj_allocated_since_prev_marking(o)) {
3288 size_t obj_size = o->size(); // Make sure we don't overflow
3289 _live_bytes += (obj_size * HeapWordSize);
3290 }
3291 }
3292 }
3293 size_t live_bytes() { return _live_bytes; }
3294 };
3295
3296 class PrintObjsInRegionClosure : public ObjectClosure {
3297 HeapRegion *_hr;
3298 G1CollectedHeap *_g1;
3299 public:
3300 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3301 _g1 = G1CollectedHeap::heap();
3302 };
3303
3304 void do_object(oop o) {
3305 if (o != NULL) {
3306 HeapWord *start = (HeapWord *) o;
3307 size_t word_sz = o->size();
3308 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3309 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3310 (void*) o, word_sz,
3311 _g1->isMarkedPrev(o),
3312 _g1->isMarkedNext(o),
3313 _hr->obj_allocated_since_prev_marking(o));
3314 HeapWord *end = start + word_sz;
3315 HeapWord *cur;
3316 int *val;
3317 for (cur = start; cur < end; cur++) {
3318 val = (int *) cur;
3319 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3320 }
3321 }
3322 }
3323 };
3324
3325 class VerifyRegionClosure: public HeapRegionClosure {
3326 private:
3327 bool _par;
3328 VerifyOption _vo;
3329 bool _failures;
3330 public:
3331 // _vo == UsePrevMarking -> use "prev" marking information,
3332 // _vo == UseNextMarking -> use "next" marking information,
3333 // _vo == UseMarkWord -> use mark word from object header.
3334 VerifyRegionClosure(bool par, VerifyOption vo)
3335 : _par(par),
3336 _vo(vo),
3337 _failures(false) {}
3338
3339 bool failures() {
3340 return _failures;
3341 }
3342
3343 bool doHeapRegion(HeapRegion* r) {
3344 if (!r->continuesHumongous()) {
3345 bool failures = false;
3346 r->verify(_vo, &failures);
3347 if (failures) {
3348 _failures = true;
3349 } else {
3350 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3351 r->object_iterate(¬_dead_yet_cl);
3352 if (_vo != VerifyOption_G1UseNextMarking) {
3353 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3354 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3355 "max_live_bytes "SIZE_FORMAT" "
3356 "< calculated "SIZE_FORMAT,
3357 r->bottom(), r->end(),
3358 r->max_live_bytes(),
3359 not_dead_yet_cl.live_bytes());
3360 _failures = true;
3361 }
3362 } else {
3363 // When vo == UseNextMarking we cannot currently do a sanity
3364 // check on the live bytes as the calculation has not been
3365 // finalized yet.
3366 }
3367 }
3368 }
3369 return false; // stop the region iteration if we hit a failure
3370 }
3371 };
3372
3373 // This is the task used for parallel verification of the heap regions
3374
3375 class G1ParVerifyTask: public AbstractGangTask {
3376 private:
3377 G1CollectedHeap* _g1h;
3378 VerifyOption _vo;
3379 bool _failures;
3380
3381 public:
3382 // _vo == UsePrevMarking -> use "prev" marking information,
3383 // _vo == UseNextMarking -> use "next" marking information,
3384 // _vo == UseMarkWord -> use mark word from object header.
3385 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3386 AbstractGangTask("Parallel verify task"),
3387 _g1h(g1h),
3388 _vo(vo),
3389 _failures(false) { }
3390
3391 bool failures() {
3392 return _failures;
3393 }
3394
3395 void work(uint worker_id) {
3396 HandleMark hm;
3397 VerifyRegionClosure blk(true, _vo);
3398 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3399 _g1h->workers()->active_workers(),
3400 HeapRegion::ParVerifyClaimValue);
3401 if (blk.failures()) {
3402 _failures = true;
3403 }
3404 }
3405 };
3406
3407 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3408 if (SafepointSynchronize::is_at_safepoint()) {
3409 assert(Thread::current()->is_VM_thread(),
3410 "Expected to be executed serially by the VM thread at this point");
3411
3412 if (!silent) { gclog_or_tty->print("Roots "); }
3413 VerifyRootsClosure rootsCl(vo);
3414 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3415 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3416 VerifyKlassClosure klassCl(this, &rootsCl);
3417
3418 // We apply the relevant closures to all the oops in the
3419 // system dictionary, the string table and the code cache.
3420 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3421
3422 // Need cleared claim bits for the strong roots processing
3423 ClassLoaderDataGraph::clear_claimed_marks();
3424
3425 process_strong_roots(true, // activate StrongRootsScope
3426 false, // we set "is scavenging" to false,
3427 // so we don't reset the dirty cards.
3428 ScanningOption(so), // roots scanning options
3429 &rootsCl,
3430 &blobsCl,
3431 &klassCl
3432 );
3433
3434 bool failures = rootsCl.failures() || codeRootsCl.failures();
3435
3436 if (vo != VerifyOption_G1UseMarkWord) {
3437 // If we're verifying during a full GC then the region sets
3438 // will have been torn down at the start of the GC. Therefore
3439 // verifying the region sets will fail. So we only verify
3440 // the region sets when not in a full GC.
3441 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3442 verify_region_sets();
3443 }
3444
3445 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3446 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3447 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3448 "sanity check");
3449
3450 G1ParVerifyTask task(this, vo);
3451 assert(UseDynamicNumberOfGCThreads ||
3452 workers()->active_workers() == workers()->total_workers(),
3453 "If not dynamic should be using all the workers");
3454 int n_workers = workers()->active_workers();
3455 set_par_threads(n_workers);
3456 workers()->run_task(&task);
3457 set_par_threads(0);
3458 if (task.failures()) {
3459 failures = true;
3460 }
3461
3462 // Checks that the expected amount of parallel work was done.
3463 // The implication is that n_workers is > 0.
3464 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3465 "sanity check");
3466
3467 reset_heap_region_claim_values();
3468
3469 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3470 "sanity check");
3471 } else {
3472 VerifyRegionClosure blk(false, vo);
3473 heap_region_iterate(&blk);
3474 if (blk.failures()) {
3475 failures = true;
3476 }
3477 }
3478 if (!silent) gclog_or_tty->print("RemSet ");
3479 rem_set()->verify();
3480
3481 if (failures) {
3482 gclog_or_tty->print_cr("Heap:");
3483 // It helps to have the per-region information in the output to
3484 // help us track down what went wrong. This is why we call
3485 // print_extended_on() instead of print_on().
3486 print_extended_on(gclog_or_tty);
3487 gclog_or_tty->print_cr("");
3488 #ifndef PRODUCT
3489 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3490 concurrent_mark()->print_reachable("at-verification-failure",
3491 vo, false /* all */);
3492 }
3493 #endif
3494 gclog_or_tty->flush();
3495 }
3496 guarantee(!failures, "there should not have been any failures");
3497 } else {
3498 if (!silent)
3499 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3500 }
3501 }
3502
3503 void G1CollectedHeap::verify(bool silent) {
3504 verify(silent, VerifyOption_G1UsePrevMarking);
3505 }
3506
3507 double G1CollectedHeap::verify(bool guard, const char* msg) {
3508 double verify_time_ms = 0.0;
3509
3510 if (guard && total_collections() >= VerifyGCStartAt) {
3511 double verify_start = os::elapsedTime();
3512 HandleMark hm; // Discard invalid handles created during verification
3513 prepare_for_verify();
3514 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3515 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3516 }
3517
3518 return verify_time_ms;
3519 }
3520
3521 void G1CollectedHeap::verify_before_gc() {
3522 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3523 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3524 }
3525
3526 void G1CollectedHeap::verify_after_gc() {
3527 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3528 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3529 }
3530
3531 class PrintRegionClosure: public HeapRegionClosure {
3532 outputStream* _st;
3533 public:
3534 PrintRegionClosure(outputStream* st) : _st(st) {}
3535 bool doHeapRegion(HeapRegion* r) {
3536 r->print_on(_st);
3537 return false;
3538 }
3539 };
3540
3541 void G1CollectedHeap::print_on(outputStream* st) const {
3542 st->print(" %-20s", "garbage-first heap");
3543 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3544 capacity()/K, used_unlocked()/K);
3545 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3546 _g1_storage.low_boundary(),
3547 _g1_storage.high(),
3548 _g1_storage.high_boundary());
3549 st->cr();
3550 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3551 uint young_regions = _young_list->length();
3552 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3553 (size_t) young_regions * HeapRegion::GrainBytes / K);
3554 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3555 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3556 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3557 st->cr();
3558 MetaspaceAux::print_on(st);
3559 }
3560
3561 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3562 print_on(st);
3563
3564 // Print the per-region information.
3565 st->cr();
3566 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3567 "HS=humongous(starts), HC=humongous(continues), "
3568 "CS=collection set, F=free, TS=gc time stamp, "
3569 "PTAMS=previous top-at-mark-start, "
3570 "NTAMS=next top-at-mark-start)");
3571 PrintRegionClosure blk(st);
3572 heap_region_iterate(&blk);
3573 }
3574
3575 void G1CollectedHeap::print_on_error(outputStream* st) const {
3576 this->CollectedHeap::print_on_error(st);
3577
3578 if (_cm != NULL) {
3579 st->cr();
3580 _cm->print_on_error(st);
3581 }
3582 }
3583
3584 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3585 if (G1CollectedHeap::use_parallel_gc_threads()) {
3586 workers()->print_worker_threads_on(st);
3587 }
3588 _cmThread->print_on(st);
3589 st->cr();
3590 _cm->print_worker_threads_on(st);
3591 _cg1r->print_worker_threads_on(st);
3592 }
3593
3594 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3595 if (G1CollectedHeap::use_parallel_gc_threads()) {
3596 workers()->threads_do(tc);
3597 }
3598 tc->do_thread(_cmThread);
3599 _cg1r->threads_do(tc);
3600 }
3601
3602 void G1CollectedHeap::print_tracing_info() const {
3603 // We'll overload this to mean "trace GC pause statistics."
3604 if (TraceGen0Time || TraceGen1Time) {
3605 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3606 // to that.
3607 g1_policy()->print_tracing_info();
3608 }
3609 if (G1SummarizeRSetStats) {
3610 g1_rem_set()->print_summary_info();
3611 }
3612 if (G1SummarizeConcMark) {
3613 concurrent_mark()->print_summary_info();
3614 }
3615 g1_policy()->print_yg_surv_rate_info();
3616 SpecializationStats::print();
3617 }
3618
3619 #ifndef PRODUCT
3620 // Helpful for debugging RSet issues.
3621
3622 class PrintRSetsClosure : public HeapRegionClosure {
3623 private:
3624 const char* _msg;
3625 size_t _occupied_sum;
3626
3627 public:
3628 bool doHeapRegion(HeapRegion* r) {
3629 HeapRegionRemSet* hrrs = r->rem_set();
3630 size_t occupied = hrrs->occupied();
3631 _occupied_sum += occupied;
3632
3633 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3634 HR_FORMAT_PARAMS(r));
3635 if (occupied == 0) {
3636 gclog_or_tty->print_cr(" RSet is empty");
3637 } else {
3638 hrrs->print();
3639 }
3640 gclog_or_tty->print_cr("----------");
3641 return false;
3642 }
3643
3644 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3645 gclog_or_tty->cr();
3646 gclog_or_tty->print_cr("========================================");
3647 gclog_or_tty->print_cr(msg);
3648 gclog_or_tty->cr();
3649 }
3650
3651 ~PrintRSetsClosure() {
3652 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3653 gclog_or_tty->print_cr("========================================");
3654 gclog_or_tty->cr();
3655 }
3656 };
3657
3658 void G1CollectedHeap::print_cset_rsets() {
3659 PrintRSetsClosure cl("Printing CSet RSets");
3660 collection_set_iterate(&cl);
3661 }
3662
3663 void G1CollectedHeap::print_all_rsets() {
3664 PrintRSetsClosure cl("Printing All RSets");;
3665 heap_region_iterate(&cl);
3666 }
3667 #endif // PRODUCT
3668
3669 G1CollectedHeap* G1CollectedHeap::heap() {
3670 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3671 "not a garbage-first heap");
3672 return _g1h;
3673 }
3674
3675 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3676 // always_do_update_barrier = false;
3677 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3678 // Fill TLAB's and such
3679 ensure_parsability(true);
3680 }
3681
3682 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3683
3684 if (G1SummarizeRSetStats &&
3685 (G1SummarizeRSetStatsPeriod > 0) &&
3686 // we are at the end of the GC. Total collections has already been increased.
3687 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3688 g1_rem_set()->print_periodic_summary_info();
3689 }
3690
3691 // FIXME: what is this about?
3692 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3693 // is set.
3694 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3695 "derived pointer present"));
3696 // always_do_update_barrier = true;
3697
3698 // We have just completed a GC. Update the soft reference
3699 // policy with the new heap occupancy
3700 Universe::update_heap_info_at_gc();
3701 }
3702
3703 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3704 unsigned int gc_count_before,
3705 bool* succeeded,
3706 GCCause::Cause gc_cause) {
3707 assert_heap_not_locked_and_not_at_safepoint();
3708 g1_policy()->record_stop_world_start();
3709 VM_G1IncCollectionPause op(gc_count_before,
3710 word_size,
3711 false, /* should_initiate_conc_mark */
3712 g1_policy()->max_pause_time_ms(),
3713 gc_cause);
3714 VMThread::execute(&op);
3715
3716 HeapWord* result = op.result();
3717 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3718 assert(result == NULL || ret_succeeded,
3719 "the result should be NULL if the VM did not succeed");
3720 *succeeded = ret_succeeded;
3721
3722 assert_heap_not_locked();
3723 return result;
3724 }
3725
3726 void
3727 G1CollectedHeap::doConcurrentMark() {
3728 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3729 if (!_cmThread->in_progress()) {
3730 _cmThread->set_started();
3731 CGC_lock->notify();
3732 }
3733 }
3734
3735 size_t G1CollectedHeap::pending_card_num() {
3736 size_t extra_cards = 0;
3737 JavaThread *curr = Threads::first();
3738 while (curr != NULL) {
3739 DirtyCardQueue& dcq = curr->dirty_card_queue();
3740 extra_cards += dcq.size();
3741 curr = curr->next();
3742 }
3743 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3744 size_t buffer_size = dcqs.buffer_size();
3745 size_t buffer_num = dcqs.completed_buffers_num();
3746
3747 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3748 // in bytes - not the number of 'entries'. We need to convert
3749 // into a number of cards.
3750 return (buffer_size * buffer_num + extra_cards) / oopSize;
3751 }
3752
3753 size_t G1CollectedHeap::cards_scanned() {
3754 return g1_rem_set()->cardsScanned();
3755 }
3756
3757 void
3758 G1CollectedHeap::setup_surviving_young_words() {
3759 assert(_surviving_young_words == NULL, "pre-condition");
3760 uint array_length = g1_policy()->young_cset_region_length();
3761 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3762 if (_surviving_young_words == NULL) {
3763 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3764 "Not enough space for young surv words summary.");
3765 }
3766 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3767 #ifdef ASSERT
3768 for (uint i = 0; i < array_length; ++i) {
3769 assert( _surviving_young_words[i] == 0, "memset above" );
3770 }
3771 #endif // !ASSERT
3772 }
3773
3774 void
3775 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3776 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3777 uint array_length = g1_policy()->young_cset_region_length();
3778 for (uint i = 0; i < array_length; ++i) {
3779 _surviving_young_words[i] += surv_young_words[i];
3780 }
3781 }
3782
3783 void
3784 G1CollectedHeap::cleanup_surviving_young_words() {
3785 guarantee( _surviving_young_words != NULL, "pre-condition" );
3786 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3787 _surviving_young_words = NULL;
3788 }
3789
3790 #ifdef ASSERT
3791 class VerifyCSetClosure: public HeapRegionClosure {
3792 public:
3793 bool doHeapRegion(HeapRegion* hr) {
3794 // Here we check that the CSet region's RSet is ready for parallel
3795 // iteration. The fields that we'll verify are only manipulated
3796 // when the region is part of a CSet and is collected. Afterwards,
3797 // we reset these fields when we clear the region's RSet (when the
3798 // region is freed) so they are ready when the region is
3799 // re-allocated. The only exception to this is if there's an
3800 // evacuation failure and instead of freeing the region we leave
3801 // it in the heap. In that case, we reset these fields during
3802 // evacuation failure handling.
3803 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3804
3805 // Here's a good place to add any other checks we'd like to
3806 // perform on CSet regions.
3807 return false;
3808 }
3809 };
3810 #endif // ASSERT
3811
3812 #if TASKQUEUE_STATS
3813 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3814 st->print_raw_cr("GC Task Stats");
3815 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3816 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3817 }
3818
3819 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3820 print_taskqueue_stats_hdr(st);
3821
3822 TaskQueueStats totals;
3823 const int n = workers() != NULL ? workers()->total_workers() : 1;
3824 for (int i = 0; i < n; ++i) {
3825 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3826 totals += task_queue(i)->stats;
3827 }
3828 st->print_raw("tot "); totals.print(st); st->cr();
3829
3830 DEBUG_ONLY(totals.verify());
3831 }
3832
3833 void G1CollectedHeap::reset_taskqueue_stats() {
3834 const int n = workers() != NULL ? workers()->total_workers() : 1;
3835 for (int i = 0; i < n; ++i) {
3836 task_queue(i)->stats.reset();
3837 }
3838 }
3839 #endif // TASKQUEUE_STATS
3840
3841 void G1CollectedHeap::log_gc_header() {
3842 if (!G1Log::fine()) {
3843 return;
3844 }
3845
3846 gclog_or_tty->date_stamp(PrintGCDateStamps);
3847 gclog_or_tty->stamp(PrintGCTimeStamps);
3848
3849 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3850 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3851 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3852
3853 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3854 }
3855
3856 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3857 if (!G1Log::fine()) {
3858 return;
3859 }
3860
3861 if (G1Log::finer()) {
3862 if (evacuation_failed()) {
3863 gclog_or_tty->print(" (to-space exhausted)");
3864 }
3865 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3866 g1_policy()->phase_times()->note_gc_end();
3867 g1_policy()->phase_times()->print(pause_time_sec);
3868 g1_policy()->print_detailed_heap_transition();
3869 } else {
3870 if (evacuation_failed()) {
3871 gclog_or_tty->print("--");
3872 }
3873 g1_policy()->print_heap_transition();
3874 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3875 }
3876 gclog_or_tty->flush();
3877 }
3878
3879 bool
3880 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3881 assert_at_safepoint(true /* should_be_vm_thread */);
3882 guarantee(!is_gc_active(), "collection is not reentrant");
3883
3884 if (GC_locker::check_active_before_gc()) {
3885 return false;
3886 }
3887
3888 _gc_timer_stw->register_gc_start(os::elapsed_counter());
3889
3890 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3891
3892 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3893 ResourceMark rm;
3894
3895 print_heap_before_gc();
3896 trace_heap_before_gc(_gc_tracer_stw);
3897
3898 HRSPhaseSetter x(HRSPhaseEvacuation);
3899 verify_region_sets_optional();
3900 verify_dirty_young_regions();
3901
3902 // This call will decide whether this pause is an initial-mark
3903 // pause. If it is, during_initial_mark_pause() will return true
3904 // for the duration of this pause.
3905 g1_policy()->decide_on_conc_mark_initiation();
3906
3907 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3908 assert(!g1_policy()->during_initial_mark_pause() ||
3909 g1_policy()->gcs_are_young(), "sanity");
3910
3911 // We also do not allow mixed GCs during marking.
3912 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3913
3914 // Record whether this pause is an initial mark. When the current
3915 // thread has completed its logging output and it's safe to signal
3916 // the CM thread, the flag's value in the policy has been reset.
3917 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3918
3919 // Inner scope for scope based logging, timers, and stats collection
3920 {
3921 EvacuationInfo evacuation_info;
3922
3923 if (g1_policy()->during_initial_mark_pause()) {
3924 // We are about to start a marking cycle, so we increment the
3925 // full collection counter.
3926 increment_old_marking_cycles_started();
3927 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3928 }
3929
3930 _gc_tracer_stw->report_yc_type(yc_type());
3931
3932 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3933
3934 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3935 workers()->active_workers() : 1);
3936 double pause_start_sec = os::elapsedTime();
3937 g1_policy()->phase_times()->note_gc_start(active_workers);
3938 log_gc_header();
3939
3940 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3941 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3942
3943 // If the secondary_free_list is not empty, append it to the
3944 // free_list. No need to wait for the cleanup operation to finish;
3945 // the region allocation code will check the secondary_free_list
3946 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3947 // set, skip this step so that the region allocation code has to
3948 // get entries from the secondary_free_list.
3949 if (!G1StressConcRegionFreeing) {
3950 append_secondary_free_list_if_not_empty_with_lock();
3951 }
3952
3953 assert(check_young_list_well_formed(), "young list should be well formed");
3954 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3955 "sanity check");
3956
3957 // Don't dynamically change the number of GC threads this early. A value of
3958 // 0 is used to indicate serial work. When parallel work is done,
3959 // it will be set.
3960
3961 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3962 IsGCActiveMark x;
3963
3964 gc_prologue(false);
3965 increment_total_collections(false /* full gc */);
3966 increment_gc_time_stamp();
3967
3968 verify_before_gc();
3969
3970 COMPILER2_PRESENT(DerivedPointerTable::clear());
3971
3972 // Please see comment in g1CollectedHeap.hpp and
3973 // G1CollectedHeap::ref_processing_init() to see how
3974 // reference processing currently works in G1.
3975
3976 // Enable discovery in the STW reference processor
3977 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3978 true /*verify_no_refs*/);
3979
3980 {
3981 // We want to temporarily turn off discovery by the
3982 // CM ref processor, if necessary, and turn it back on
3983 // on again later if we do. Using a scoped
3984 // NoRefDiscovery object will do this.
3985 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3986
3987 // Forget the current alloc region (we might even choose it to be part
3988 // of the collection set!).
3989 release_mutator_alloc_region();
3990
3991 // We should call this after we retire the mutator alloc
3992 // region(s) so that all the ALLOC / RETIRE events are generated
3993 // before the start GC event.
3994 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3995
3996 // This timing is only used by the ergonomics to handle our pause target.
3997 // It is unclear why this should not include the full pause. We will
3998 // investigate this in CR 7178365.
3999 //
4000 // Preserving the old comment here if that helps the investigation:
4001 //
4002 // The elapsed time induced by the start time below deliberately elides
4003 // the possible verification above.
4004 double sample_start_time_sec = os::elapsedTime();
4005
4006 #if YOUNG_LIST_VERBOSE
4007 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4008 _young_list->print();
4009 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4010 #endif // YOUNG_LIST_VERBOSE
4011
4012 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4013
4014 double scan_wait_start = os::elapsedTime();
4015 // We have to wait until the CM threads finish scanning the
4016 // root regions as it's the only way to ensure that all the
4017 // objects on them have been correctly scanned before we start
4018 // moving them during the GC.
4019 bool waited = _cm->root_regions()->wait_until_scan_finished();
4020 double wait_time_ms = 0.0;
4021 if (waited) {
4022 double scan_wait_end = os::elapsedTime();
4023 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4024 }
4025 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4026
4027 #if YOUNG_LIST_VERBOSE
4028 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4029 _young_list->print();
4030 #endif // YOUNG_LIST_VERBOSE
4031
4032 if (g1_policy()->during_initial_mark_pause()) {
4033 concurrent_mark()->checkpointRootsInitialPre();
4034 }
4035
4036 #if YOUNG_LIST_VERBOSE
4037 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4038 _young_list->print();
4039 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4040 #endif // YOUNG_LIST_VERBOSE
4041
4042 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4043
4044 _cm->note_start_of_gc();
4045 // We should not verify the per-thread SATB buffers given that
4046 // we have not filtered them yet (we'll do so during the
4047 // GC). We also call this after finalize_cset() to
4048 // ensure that the CSet has been finalized.
4049 _cm->verify_no_cset_oops(true /* verify_stacks */,
4050 true /* verify_enqueued_buffers */,
4051 false /* verify_thread_buffers */,
4052 true /* verify_fingers */);
4053
4054 if (_hr_printer.is_active()) {
4055 HeapRegion* hr = g1_policy()->collection_set();
4056 while (hr != NULL) {
4057 G1HRPrinter::RegionType type;
4058 if (!hr->is_young()) {
4059 type = G1HRPrinter::Old;
4060 } else if (hr->is_survivor()) {
4061 type = G1HRPrinter::Survivor;
4062 } else {
4063 type = G1HRPrinter::Eden;
4064 }
4065 _hr_printer.cset(hr);
4066 hr = hr->next_in_collection_set();
4067 }
4068 }
4069
4070 #ifdef ASSERT
4071 VerifyCSetClosure cl;
4072 collection_set_iterate(&cl);
4073 #endif // ASSERT
4074
4075 setup_surviving_young_words();
4076
4077 // Initialize the GC alloc regions.
4078 init_gc_alloc_regions(evacuation_info);
4079
4080 // Actually do the work...
4081 evacuate_collection_set(evacuation_info);
4082
4083 // We do this to mainly verify the per-thread SATB buffers
4084 // (which have been filtered by now) since we didn't verify
4085 // them earlier. No point in re-checking the stacks / enqueued
4086 // buffers given that the CSet has not changed since last time
4087 // we checked.
4088 _cm->verify_no_cset_oops(false /* verify_stacks */,
4089 false /* verify_enqueued_buffers */,
4090 true /* verify_thread_buffers */,
4091 true /* verify_fingers */);
4092
4093 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4094 g1_policy()->clear_collection_set();
4095
4096 cleanup_surviving_young_words();
4097
4098 // Start a new incremental collection set for the next pause.
4099 g1_policy()->start_incremental_cset_building();
4100
4101 // Clear the _cset_fast_test bitmap in anticipation of adding
4102 // regions to the incremental collection set for the next
4103 // evacuation pause.
4104 clear_cset_fast_test();
4105
4106 _young_list->reset_sampled_info();
4107
4108 // Don't check the whole heap at this point as the
4109 // GC alloc regions from this pause have been tagged
4110 // as survivors and moved on to the survivor list.
4111 // Survivor regions will fail the !is_young() check.
4112 assert(check_young_list_empty(false /* check_heap */),
4113 "young list should be empty");
4114
4115 #if YOUNG_LIST_VERBOSE
4116 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4117 _young_list->print();
4118 #endif // YOUNG_LIST_VERBOSE
4119
4120 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4121 _young_list->first_survivor_region(),
4122 _young_list->last_survivor_region());
4123
4124 _young_list->reset_auxilary_lists();
4125
4126 if (evacuation_failed()) {
4127 _summary_bytes_used = recalculate_used();
4128 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4129 for (uint i = 0; i < n_queues; i++) {
4130 if (_evacuation_failed_info_array[i].has_failed()) {
4131 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4132 }
4133 }
4134 } else {
4135 // The "used" of the the collection set have already been subtracted
4136 // when they were freed. Add in the bytes evacuated.
4137 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4138 }
4139
4140 if (g1_policy()->during_initial_mark_pause()) {
4141 // We have to do this before we notify the CM threads that
4142 // they can start working to make sure that all the
4143 // appropriate initialization is done on the CM object.
4144 concurrent_mark()->checkpointRootsInitialPost();
4145 set_marking_started();
4146 // Note that we don't actually trigger the CM thread at
4147 // this point. We do that later when we're sure that
4148 // the current thread has completed its logging output.
4149 }
4150
4151 allocate_dummy_regions();
4152
4153 #if YOUNG_LIST_VERBOSE
4154 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4155 _young_list->print();
4156 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4157 #endif // YOUNG_LIST_VERBOSE
4158
4159 init_mutator_alloc_region();
4160
4161 {
4162 size_t expand_bytes = g1_policy()->expansion_amount();
4163 if (expand_bytes > 0) {
4164 size_t bytes_before = capacity();
4165 // No need for an ergo verbose message here,
4166 // expansion_amount() does this when it returns a value > 0.
4167 if (!expand(expand_bytes)) {
4168 // We failed to expand the heap so let's verify that
4169 // committed/uncommitted amount match the backing store
4170 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4171 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4172 }
4173 }
4174 }
4175
4176 // We redo the verification but now wrt to the new CSet which
4177 // has just got initialized after the previous CSet was freed.
4178 _cm->verify_no_cset_oops(true /* verify_stacks */,
4179 true /* verify_enqueued_buffers */,
4180 true /* verify_thread_buffers */,
4181 true /* verify_fingers */);
4182 _cm->note_end_of_gc();
4183
4184 // This timing is only used by the ergonomics to handle our pause target.
4185 // It is unclear why this should not include the full pause. We will
4186 // investigate this in CR 7178365.
4187 double sample_end_time_sec = os::elapsedTime();
4188 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4189 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4190
4191 MemoryService::track_memory_usage();
4192
4193 // In prepare_for_verify() below we'll need to scan the deferred
4194 // update buffers to bring the RSets up-to-date if
4195 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4196 // the update buffers we'll probably need to scan cards on the
4197 // regions we just allocated to (i.e., the GC alloc
4198 // regions). However, during the last GC we called
4199 // set_saved_mark() on all the GC alloc regions, so card
4200 // scanning might skip the [saved_mark_word()...top()] area of
4201 // those regions (i.e., the area we allocated objects into
4202 // during the last GC). But it shouldn't. Given that
4203 // saved_mark_word() is conditional on whether the GC time stamp
4204 // on the region is current or not, by incrementing the GC time
4205 // stamp here we invalidate all the GC time stamps on all the
4206 // regions and saved_mark_word() will simply return top() for
4207 // all the regions. This is a nicer way of ensuring this rather
4208 // than iterating over the regions and fixing them. In fact, the
4209 // GC time stamp increment here also ensures that
4210 // saved_mark_word() will return top() between pauses, i.e.,
4211 // during concurrent refinement. So we don't need the
4212 // is_gc_active() check to decided which top to use when
4213 // scanning cards (see CR 7039627).
4214 increment_gc_time_stamp();
4215
4216 verify_after_gc();
4217
4218 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4219 ref_processor_stw()->verify_no_references_recorded();
4220
4221 // CM reference discovery will be re-enabled if necessary.
4222 }
4223
4224 // We should do this after we potentially expand the heap so
4225 // that all the COMMIT events are generated before the end GC
4226 // event, and after we retire the GC alloc regions so that all
4227 // RETIRE events are generated before the end GC event.
4228 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4229
4230 if (mark_in_progress()) {
4231 concurrent_mark()->update_g1_committed();
4232 }
4233
4234 #ifdef TRACESPINNING
4235 ParallelTaskTerminator::print_termination_counts();
4236 #endif
4237
4238 gc_epilogue(false);
4239 }
4240
4241 // Print the remainder of the GC log output.
4242 log_gc_footer(os::elapsedTime() - pause_start_sec);
4243
4244 // It is not yet to safe to tell the concurrent mark to
4245 // start as we have some optional output below. We don't want the
4246 // output from the concurrent mark thread interfering with this
4247 // logging output either.
4248
4249 _hrs.verify_optional();
4250 verify_region_sets_optional();
4251
4252 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4253 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4254
4255 print_heap_after_gc();
4256 trace_heap_after_gc(_gc_tracer_stw);
4257
4258 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4259 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4260 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4261 // before any GC notifications are raised.
4262 g1mm()->update_sizes();
4263
4264 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4265 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4266 _gc_timer_stw->register_gc_end(os::elapsed_counter());
4267 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4268 }
4269 // It should now be safe to tell the concurrent mark thread to start
4270 // without its logging output interfering with the logging output
4271 // that came from the pause.
4272
4273 if (should_start_conc_mark) {
4274 // CAUTION: after the doConcurrentMark() call below,
4275 // the concurrent marking thread(s) could be running
4276 // concurrently with us. Make sure that anything after
4277 // this point does not assume that we are the only GC thread
4278 // running. Note: of course, the actual marking work will
4279 // not start until the safepoint itself is released in
4280 // ConcurrentGCThread::safepoint_desynchronize().
4281 doConcurrentMark();
4282 }
4283
4284 return true;
4285 }
4286
4287 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4288 {
4289 size_t gclab_word_size;
4290 switch (purpose) {
4291 case GCAllocForSurvived:
4292 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4293 break;
4294 case GCAllocForTenured:
4295 gclab_word_size = _old_plab_stats.desired_plab_sz();
4296 break;
4297 default:
4298 assert(false, "unknown GCAllocPurpose");
4299 gclab_word_size = _old_plab_stats.desired_plab_sz();
4300 break;
4301 }
4302
4303 // Prevent humongous PLAB sizes for two reasons:
4304 // * PLABs are allocated using a similar paths as oops, but should
4305 // never be in a humongous region
4306 // * Allowing humongous PLABs needlessly churns the region free lists
4307 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4308 }
4309
4310 void G1CollectedHeap::init_mutator_alloc_region() {
4311 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4312 _mutator_alloc_region.init();
4313 }
4314
4315 void G1CollectedHeap::release_mutator_alloc_region() {
4316 _mutator_alloc_region.release();
4317 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4318 }
4319
4320 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4321 assert_at_safepoint(true /* should_be_vm_thread */);
4322
4323 _survivor_gc_alloc_region.init();
4324 _old_gc_alloc_region.init();
4325 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4326 _retained_old_gc_alloc_region = NULL;
4327
4328 // We will discard the current GC alloc region if:
4329 // a) it's in the collection set (it can happen!),
4330 // b) it's already full (no point in using it),
4331 // c) it's empty (this means that it was emptied during
4332 // a cleanup and it should be on the free list now), or
4333 // d) it's humongous (this means that it was emptied
4334 // during a cleanup and was added to the free list, but
4335 // has been subsequently used to allocate a humongous
4336 // object that may be less than the region size).
4337 if (retained_region != NULL &&
4338 !retained_region->in_collection_set() &&
4339 !(retained_region->top() == retained_region->end()) &&
4340 !retained_region->is_empty() &&
4341 !retained_region->isHumongous()) {
4342 retained_region->set_saved_mark();
4343 // The retained region was added to the old region set when it was
4344 // retired. We have to remove it now, since we don't allow regions
4345 // we allocate to in the region sets. We'll re-add it later, when
4346 // it's retired again.
4347 _old_set.remove(retained_region);
4348 bool during_im = g1_policy()->during_initial_mark_pause();
4349 retained_region->note_start_of_copying(during_im);
4350 _old_gc_alloc_region.set(retained_region);
4351 _hr_printer.reuse(retained_region);
4352 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4353 }
4354 }
4355
4356 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4357 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4358 _old_gc_alloc_region.count());
4359 _survivor_gc_alloc_region.release();
4360 // If we have an old GC alloc region to release, we'll save it in
4361 // _retained_old_gc_alloc_region. If we don't
4362 // _retained_old_gc_alloc_region will become NULL. This is what we
4363 // want either way so no reason to check explicitly for either
4364 // condition.
4365 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4366
4367 if (ResizePLAB) {
4368 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4369 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4370 }
4371 }
4372
4373 void G1CollectedHeap::abandon_gc_alloc_regions() {
4374 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4375 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4376 _retained_old_gc_alloc_region = NULL;
4377 }
4378
4379 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4380 _drain_in_progress = false;
4381 set_evac_failure_closure(cl);
4382 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4383 }
4384
4385 void G1CollectedHeap::finalize_for_evac_failure() {
4386 assert(_evac_failure_scan_stack != NULL &&
4387 _evac_failure_scan_stack->length() == 0,
4388 "Postcondition");
4389 assert(!_drain_in_progress, "Postcondition");
4390 delete _evac_failure_scan_stack;
4391 _evac_failure_scan_stack = NULL;
4392 }
4393
4394 void G1CollectedHeap::remove_self_forwarding_pointers() {
4395 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4396
4397 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4398
4399 if (G1CollectedHeap::use_parallel_gc_threads()) {
4400 set_par_threads();
4401 workers()->run_task(&rsfp_task);
4402 set_par_threads(0);
4403 } else {
4404 rsfp_task.work(0);
4405 }
4406
4407 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4408
4409 // Reset the claim values in the regions in the collection set.
4410 reset_cset_heap_region_claim_values();
4411
4412 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4413
4414 // Now restore saved marks, if any.
4415 assert(_objs_with_preserved_marks.size() ==
4416 _preserved_marks_of_objs.size(), "Both or none.");
4417 while (!_objs_with_preserved_marks.is_empty()) {
4418 oop obj = _objs_with_preserved_marks.pop();
4419 markOop m = _preserved_marks_of_objs.pop();
4420 obj->set_mark(m);
4421 }
4422 _objs_with_preserved_marks.clear(true);
4423 _preserved_marks_of_objs.clear(true);
4424 }
4425
4426 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4427 _evac_failure_scan_stack->push(obj);
4428 }
4429
4430 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4431 assert(_evac_failure_scan_stack != NULL, "precondition");
4432
4433 while (_evac_failure_scan_stack->length() > 0) {
4434 oop obj = _evac_failure_scan_stack->pop();
4435 _evac_failure_closure->set_region(heap_region_containing(obj));
4436 obj->oop_iterate_backwards(_evac_failure_closure);
4437 }
4438 }
4439
4440 oop
4441 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4442 oop old) {
4443 assert(obj_in_cs(old),
4444 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4445 (HeapWord*) old));
4446 markOop m = old->mark();
4447 oop forward_ptr = old->forward_to_atomic(old);
4448 if (forward_ptr == NULL) {
4449 // Forward-to-self succeeded.
4450 assert(_par_scan_state != NULL, "par scan state");
4451 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4452 uint queue_num = _par_scan_state->queue_num();
4453
4454 _evacuation_failed = true;
4455 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4456 if (_evac_failure_closure != cl) {
4457 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4458 assert(!_drain_in_progress,
4459 "Should only be true while someone holds the lock.");
4460 // Set the global evac-failure closure to the current thread's.
4461 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4462 set_evac_failure_closure(cl);
4463 // Now do the common part.
4464 handle_evacuation_failure_common(old, m);
4465 // Reset to NULL.
4466 set_evac_failure_closure(NULL);
4467 } else {
4468 // The lock is already held, and this is recursive.
4469 assert(_drain_in_progress, "This should only be the recursive case.");
4470 handle_evacuation_failure_common(old, m);
4471 }
4472 return old;
4473 } else {
4474 // Forward-to-self failed. Either someone else managed to allocate
4475 // space for this object (old != forward_ptr) or they beat us in
4476 // self-forwarding it (old == forward_ptr).
4477 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4478 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4479 "should not be in the CSet",
4480 (HeapWord*) old, (HeapWord*) forward_ptr));
4481 return forward_ptr;
4482 }
4483 }
4484
4485 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4486 preserve_mark_if_necessary(old, m);
4487
4488 HeapRegion* r = heap_region_containing(old);
4489 if (!r->evacuation_failed()) {
4490 r->set_evacuation_failed(true);
4491 _hr_printer.evac_failure(r);
4492 }
4493
4494 push_on_evac_failure_scan_stack(old);
4495
4496 if (!_drain_in_progress) {
4497 // prevent recursion in copy_to_survivor_space()
4498 _drain_in_progress = true;
4499 drain_evac_failure_scan_stack();
4500 _drain_in_progress = false;
4501 }
4502 }
4503
4504 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4505 assert(evacuation_failed(), "Oversaving!");
4506 // We want to call the "for_promotion_failure" version only in the
4507 // case of a promotion failure.
4508 if (m->must_be_preserved_for_promotion_failure(obj)) {
4509 _objs_with_preserved_marks.push(obj);
4510 _preserved_marks_of_objs.push(m);
4511 }
4512 }
4513
4514 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4515 size_t word_size) {
4516 if (purpose == GCAllocForSurvived) {
4517 HeapWord* result = survivor_attempt_allocation(word_size);
4518 if (result != NULL) {
4519 return result;
4520 } else {
4521 // Let's try to allocate in the old gen in case we can fit the
4522 // object there.
4523 return old_attempt_allocation(word_size);
4524 }
4525 } else {
4526 assert(purpose == GCAllocForTenured, "sanity");
4527 HeapWord* result = old_attempt_allocation(word_size);
4528 if (result != NULL) {
4529 return result;
4530 } else {
4531 // Let's try to allocate in the survivors in case we can fit the
4532 // object there.
4533 return survivor_attempt_allocation(word_size);
4534 }
4535 }
4536
4537 ShouldNotReachHere();
4538 // Trying to keep some compilers happy.
4539 return NULL;
4540 }
4541
4542 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4543 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4544
4545 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4546 : _g1h(g1h),
4547 _refs(g1h->task_queue(queue_num)),
4548 _dcq(&g1h->dirty_card_queue_set()),
4549 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4550 _g1_rem(g1h->g1_rem_set()),
4551 _hash_seed(17), _queue_num(queue_num),
4552 _term_attempts(0),
4553 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4554 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4555 _age_table(false),
4556 _strong_roots_time(0), _term_time(0),
4557 _alloc_buffer_waste(0), _undo_waste(0) {
4558 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4559 // we "sacrifice" entry 0 to keep track of surviving bytes for
4560 // non-young regions (where the age is -1)
4561 // We also add a few elements at the beginning and at the end in
4562 // an attempt to eliminate cache contention
4563 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4564 uint array_length = PADDING_ELEM_NUM +
4565 real_length +
4566 PADDING_ELEM_NUM;
4567 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4568 if (_surviving_young_words_base == NULL)
4569 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4570 "Not enough space for young surv histo.");
4571 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4572 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4573
4574 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4575 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4576
4577 _start = os::elapsedTime();
4578 }
4579
4580 void
4581 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4582 {
4583 st->print_raw_cr("GC Termination Stats");
4584 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4585 " ------waste (KiB)------");
4586 st->print_raw_cr("thr ms ms % ms % attempts"
4587 " total alloc undo");
4588 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4589 " ------- ------- -------");
4590 }
4591
4592 void
4593 G1ParScanThreadState::print_termination_stats(int i,
4594 outputStream* const st) const
4595 {
4596 const double elapsed_ms = elapsed_time() * 1000.0;
4597 const double s_roots_ms = strong_roots_time() * 1000.0;
4598 const double term_ms = term_time() * 1000.0;
4599 st->print_cr("%3d %9.2f %9.2f %6.2f "
4600 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4601 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4602 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4603 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4604 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4605 alloc_buffer_waste() * HeapWordSize / K,
4606 undo_waste() * HeapWordSize / K);
4607 }
4608
4609 #ifdef ASSERT
4610 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4611 assert(ref != NULL, "invariant");
4612 assert(UseCompressedOops, "sanity");
4613 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4614 oop p = oopDesc::load_decode_heap_oop(ref);
4615 assert(_g1h->is_in_g1_reserved(p),
4616 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4617 return true;
4618 }
4619
4620 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4621 assert(ref != NULL, "invariant");
4622 if (has_partial_array_mask(ref)) {
4623 // Must be in the collection set--it's already been copied.
4624 oop p = clear_partial_array_mask(ref);
4625 assert(_g1h->obj_in_cs(p),
4626 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4627 } else {
4628 oop p = oopDesc::load_decode_heap_oop(ref);
4629 assert(_g1h->is_in_g1_reserved(p),
4630 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4631 }
4632 return true;
4633 }
4634
4635 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4636 if (ref.is_narrow()) {
4637 return verify_ref((narrowOop*) ref);
4638 } else {
4639 return verify_ref((oop*) ref);
4640 }
4641 }
4642 #endif // ASSERT
4643
4644 void G1ParScanThreadState::trim_queue() {
4645 assert(_evac_cl != NULL, "not set");
4646 assert(_evac_failure_cl != NULL, "not set");
4647 assert(_partial_scan_cl != NULL, "not set");
4648
4649 StarTask ref;
4650 do {
4651 // Drain the overflow stack first, so other threads can steal.
4652 while (refs()->pop_overflow(ref)) {
4653 deal_with_reference(ref);
4654 }
4655
4656 while (refs()->pop_local(ref)) {
4657 deal_with_reference(ref);
4658 }
4659 } while (!refs()->is_empty());
4660 }
4661
4662 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4663 G1ParScanThreadState* par_scan_state) :
4664 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4665 _par_scan_state(par_scan_state),
4666 _worker_id(par_scan_state->queue_num()),
4667 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4668 _mark_in_progress(_g1->mark_in_progress()) { }
4669
4670 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4671 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4672 #ifdef ASSERT
4673 HeapRegion* hr = _g1->heap_region_containing(obj);
4674 assert(hr != NULL, "sanity");
4675 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4676 #endif // ASSERT
4677
4678 // We know that the object is not moving so it's safe to read its size.
4679 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4680 }
4681
4682 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4683 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4684 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4685 #ifdef ASSERT
4686 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4687 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4688 assert(from_obj != to_obj, "should not be self-forwarded");
4689
4690 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4691 assert(from_hr != NULL, "sanity");
4692 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4693
4694 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4695 assert(to_hr != NULL, "sanity");
4696 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4697 #endif // ASSERT
4698
4699 // The object might be in the process of being copied by another
4700 // worker so we cannot trust that its to-space image is
4701 // well-formed. So we have to read its size from its from-space
4702 // image which we know should not be changing.
4703 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4704 }
4705
4706 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4707 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4708 ::copy_to_survivor_space(oop old) {
4709 size_t word_sz = old->size();
4710 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4711 // +1 to make the -1 indexes valid...
4712 int young_index = from_region->young_index_in_cset()+1;
4713 assert( (from_region->is_young() && young_index > 0) ||
4714 (!from_region->is_young() && young_index == 0), "invariant" );
4715 G1CollectorPolicy* g1p = _g1->g1_policy();
4716 markOop m = old->mark();
4717 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4718 : m->age();
4719 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4720 word_sz);
4721 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4722 #ifndef PRODUCT
4723 // Should this evacuation fail?
4724 if (_g1->evacuation_should_fail()) {
4725 if (obj_ptr != NULL) {
4726 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4727 obj_ptr = NULL;
4728 }
4729 }
4730 #endif // !PRODUCT
4731
4732 if (obj_ptr == NULL) {
4733 // This will either forward-to-self, or detect that someone else has
4734 // installed a forwarding pointer.
4735 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4736 }
4737
4738 oop obj = oop(obj_ptr);
4739
4740 // We're going to allocate linearly, so might as well prefetch ahead.
4741 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4742
4743 oop forward_ptr = old->forward_to_atomic(obj);
4744 if (forward_ptr == NULL) {
4745 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4746 if (g1p->track_object_age(alloc_purpose)) {
4747 // We could simply do obj->incr_age(). However, this causes a
4748 // performance issue. obj->incr_age() will first check whether
4749 // the object has a displaced mark by checking its mark word;
4750 // getting the mark word from the new location of the object
4751 // stalls. So, given that we already have the mark word and we
4752 // are about to install it anyway, it's better to increase the
4753 // age on the mark word, when the object does not have a
4754 // displaced mark word. We're not expecting many objects to have
4755 // a displaced marked word, so that case is not optimized
4756 // further (it could be...) and we simply call obj->incr_age().
4757
4758 if (m->has_displaced_mark_helper()) {
4759 // in this case, we have to install the mark word first,
4760 // otherwise obj looks to be forwarded (the old mark word,
4761 // which contains the forward pointer, was copied)
4762 obj->set_mark(m);
4763 obj->incr_age();
4764 } else {
4765 m = m->incr_age();
4766 obj->set_mark(m);
4767 }
4768 _par_scan_state->age_table()->add(obj, word_sz);
4769 } else {
4770 obj->set_mark(m);
4771 }
4772
4773 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4774 surv_young_words[young_index] += word_sz;
4775
4776 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4777 // We keep track of the next start index in the length field of
4778 // the to-space object. The actual length can be found in the
4779 // length field of the from-space object.
4780 arrayOop(obj)->set_length(0);
4781 oop* old_p = set_partial_array_mask(old);
4782 _par_scan_state->push_on_queue(old_p);
4783 } else {
4784 // No point in using the slower heap_region_containing() method,
4785 // given that we know obj is in the heap.
4786 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4787 obj->oop_iterate_backwards(&_scanner);
4788 }
4789 } else {
4790 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4791 obj = forward_ptr;
4792 }
4793 return obj;
4794 }
4795
4796 template <class T>
4797 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4798 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4799 _scanned_klass->record_modified_oops();
4800 }
4801 }
4802
4803 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4804 template <class T>
4805 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4806 ::do_oop_work(T* p) {
4807 oop obj = oopDesc::load_decode_heap_oop(p);
4808 assert(barrier != G1BarrierRS || obj != NULL,
4809 "Precondition: G1BarrierRS implies obj is non-NULL");
4810
4811 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4812
4813 // here the null check is implicit in the cset_fast_test() test
4814 if (_g1->in_cset_fast_test(obj)) {
4815 oop forwardee;
4816 if (obj->is_forwarded()) {
4817 forwardee = obj->forwardee();
4818 } else {
4819 forwardee = copy_to_survivor_space(obj);
4820 }
4821 assert(forwardee != NULL, "forwardee should not be NULL");
4822 oopDesc::encode_store_heap_oop(p, forwardee);
4823 if (do_mark_object && forwardee != obj) {
4824 // If the object is self-forwarded we don't need to explicitly
4825 // mark it, the evacuation failure protocol will do so.
4826 mark_forwarded_object(obj, forwardee);
4827 }
4828
4829 // When scanning the RS, we only care about objs in CS.
4830 if (barrier == G1BarrierRS) {
4831 _par_scan_state->update_rs(_from, p, _worker_id);
4832 } else if (barrier == G1BarrierKlass) {
4833 do_klass_barrier(p, forwardee);
4834 }
4835 } else {
4836 // The object is not in collection set. If we're a root scanning
4837 // closure during an initial mark pause (i.e. do_mark_object will
4838 // be true) then attempt to mark the object.
4839 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4840 mark_object(obj);
4841 }
4842 }
4843
4844 if (barrier == G1BarrierEvac && obj != NULL) {
4845 _par_scan_state->update_rs(_from, p, _worker_id);
4846 }
4847
4848 if (do_gen_barrier && obj != NULL) {
4849 par_do_barrier(p);
4850 }
4851 }
4852
4853 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4854 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4855
4856 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4857 assert(has_partial_array_mask(p), "invariant");
4858 oop from_obj = clear_partial_array_mask(p);
4859
4860 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4861 assert(from_obj->is_objArray(), "must be obj array");
4862 objArrayOop from_obj_array = objArrayOop(from_obj);
4863 // The from-space object contains the real length.
4864 int length = from_obj_array->length();
4865
4866 assert(from_obj->is_forwarded(), "must be forwarded");
4867 oop to_obj = from_obj->forwardee();
4868 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4869 objArrayOop to_obj_array = objArrayOop(to_obj);
4870 // We keep track of the next start index in the length field of the
4871 // to-space object.
4872 int next_index = to_obj_array->length();
4873 assert(0 <= next_index && next_index < length,
4874 err_msg("invariant, next index: %d, length: %d", next_index, length));
4875
4876 int start = next_index;
4877 int end = length;
4878 int remainder = end - start;
4879 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4880 if (remainder > 2 * ParGCArrayScanChunk) {
4881 end = start + ParGCArrayScanChunk;
4882 to_obj_array->set_length(end);
4883 // Push the remainder before we process the range in case another
4884 // worker has run out of things to do and can steal it.
4885 oop* from_obj_p = set_partial_array_mask(from_obj);
4886 _par_scan_state->push_on_queue(from_obj_p);
4887 } else {
4888 assert(length == end, "sanity");
4889 // We'll process the final range for this object. Restore the length
4890 // so that the heap remains parsable in case of evacuation failure.
4891 to_obj_array->set_length(end);
4892 }
4893 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4894 // Process indexes [start,end). It will also process the header
4895 // along with the first chunk (i.e., the chunk with start == 0).
4896 // Note that at this point the length field of to_obj_array is not
4897 // correct given that we are using it to keep track of the next
4898 // start index. oop_iterate_range() (thankfully!) ignores the length
4899 // field and only relies on the start / end parameters. It does
4900 // however return the size of the object which will be incorrect. So
4901 // we have to ignore it even if we wanted to use it.
4902 to_obj_array->oop_iterate_range(&_scanner, start, end);
4903 }
4904
4905 class G1ParEvacuateFollowersClosure : public VoidClosure {
4906 protected:
4907 G1CollectedHeap* _g1h;
4908 G1ParScanThreadState* _par_scan_state;
4909 RefToScanQueueSet* _queues;
4910 ParallelTaskTerminator* _terminator;
4911
4912 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4913 RefToScanQueueSet* queues() { return _queues; }
4914 ParallelTaskTerminator* terminator() { return _terminator; }
4915
4916 public:
4917 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4918 G1ParScanThreadState* par_scan_state,
4919 RefToScanQueueSet* queues,
4920 ParallelTaskTerminator* terminator)
4921 : _g1h(g1h), _par_scan_state(par_scan_state),
4922 _queues(queues), _terminator(terminator) {}
4923
4924 void do_void();
4925
4926 private:
4927 inline bool offer_termination();
4928 };
4929
4930 bool G1ParEvacuateFollowersClosure::offer_termination() {
4931 G1ParScanThreadState* const pss = par_scan_state();
4932 pss->start_term_time();
4933 const bool res = terminator()->offer_termination();
4934 pss->end_term_time();
4935 return res;
4936 }
4937
4938 void G1ParEvacuateFollowersClosure::do_void() {
4939 StarTask stolen_task;
4940 G1ParScanThreadState* const pss = par_scan_state();
4941 pss->trim_queue();
4942
4943 do {
4944 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4945 assert(pss->verify_task(stolen_task), "sanity");
4946 if (stolen_task.is_narrow()) {
4947 pss->deal_with_reference((narrowOop*) stolen_task);
4948 } else {
4949 pss->deal_with_reference((oop*) stolen_task);
4950 }
4951
4952 // We've just processed a reference and we might have made
4953 // available new entries on the queues. So we have to make sure
4954 // we drain the queues as necessary.
4955 pss->trim_queue();
4956 }
4957 } while (!offer_termination());
4958
4959 pss->retire_alloc_buffers();
4960 }
4961
4962 class G1KlassScanClosure : public KlassClosure {
4963 G1ParCopyHelper* _closure;
4964 bool _process_only_dirty;
4965 int _count;
4966 public:
4967 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4968 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4969 void do_klass(Klass* klass) {
4970 // If the klass has not been dirtied we know that there's
4971 // no references into the young gen and we can skip it.
4972 if (!_process_only_dirty || klass->has_modified_oops()) {
4973 // Clean the klass since we're going to scavenge all the metadata.
4974 klass->clear_modified_oops();
4975
4976 // Tell the closure that this klass is the Klass to scavenge
4977 // and is the one to dirty if oops are left pointing into the young gen.
4978 _closure->set_scanned_klass(klass);
4979
4980 klass->oops_do(_closure);
4981
4982 _closure->set_scanned_klass(NULL);
4983 }
4984 _count++;
4985 }
4986 };
4987
4988 class G1ParTask : public AbstractGangTask {
4989 protected:
4990 G1CollectedHeap* _g1h;
4991 RefToScanQueueSet *_queues;
4992 ParallelTaskTerminator _terminator;
4993 uint _n_workers;
4994
4995 Mutex _stats_lock;
4996 Mutex* stats_lock() { return &_stats_lock; }
4997
4998 size_t getNCards() {
4999 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5000 / G1BlockOffsetSharedArray::N_bytes;
5001 }
5002
5003 public:
5004 G1ParTask(G1CollectedHeap* g1h,
5005 RefToScanQueueSet *task_queues)
5006 : AbstractGangTask("G1 collection"),
5007 _g1h(g1h),
5008 _queues(task_queues),
5009 _terminator(0, _queues),
5010 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
5011 {}
5012
5013 RefToScanQueueSet* queues() { return _queues; }
5014
5015 RefToScanQueue *work_queue(int i) {
5016 return queues()->queue(i);
5017 }
5018
5019 ParallelTaskTerminator* terminator() { return &_terminator; }
5020
5021 virtual void set_for_termination(int active_workers) {
5022 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5023 // in the young space (_par_seq_tasks) in the G1 heap
5024 // for SequentialSubTasksDone.
5025 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5026 // both of which need setting by set_n_termination().
5027 _g1h->SharedHeap::set_n_termination(active_workers);
5028 _g1h->set_n_termination(active_workers);
5029 terminator()->reset_for_reuse(active_workers);
5030 _n_workers = active_workers;
5031 }
5032
5033 void work(uint worker_id) {
5034 if (worker_id >= _n_workers) return; // no work needed this round
5035
5036 double start_time_ms = os::elapsedTime() * 1000.0;
5037 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5038
5039 {
5040 ResourceMark rm;
5041 HandleMark hm;
5042
5043 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5044
5045 G1ParScanThreadState pss(_g1h, worker_id);
5046 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5047 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5048 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5049
5050 pss.set_evac_closure(&scan_evac_cl);
5051 pss.set_evac_failure_closure(&evac_failure_cl);
5052 pss.set_partial_scan_closure(&partial_scan_cl);
5053
5054 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5055 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5056
5057 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5058 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5059
5060 bool only_young = _g1h->g1_policy()->gcs_are_young();
5061 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5062 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5063
5064 OopClosure* scan_root_cl = &only_scan_root_cl;
5065 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5066
5067 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5068 // We also need to mark copied objects.
5069 scan_root_cl = &scan_mark_root_cl;
5070 scan_klasses_cl = &scan_mark_klasses_cl_s;
5071 }
5072
5073 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5074
5075 // Don't scan the scavengable methods in the code cache as part
5076 // of strong root scanning. The code roots that point into a
5077 // region in the collection set are scanned when we scan the
5078 // region's RSet.
5079 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5080
5081 pss.start_strong_roots();
5082 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5083 SharedHeap::ScanningOption(so),
5084 scan_root_cl,
5085 &push_heap_rs_cl,
5086 scan_klasses_cl,
5087 worker_id);
5088 pss.end_strong_roots();
5089
5090 {
5091 double start = os::elapsedTime();
5092 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5093 evac.do_void();
5094 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5095 double term_ms = pss.term_time()*1000.0;
5096 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5097 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5098 }
5099 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5100 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5101
5102 if (ParallelGCVerbose) {
5103 MutexLocker x(stats_lock());
5104 pss.print_termination_stats(worker_id);
5105 }
5106
5107 assert(pss.refs()->is_empty(), "should be empty");
5108
5109 // Close the inner scope so that the ResourceMark and HandleMark
5110 // destructors are executed here and are included as part of the
5111 // "GC Worker Time".
5112 }
5113
5114 double end_time_ms = os::elapsedTime() * 1000.0;
5115 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5116 }
5117 };
5118
5119 // *** Common G1 Evacuation Stuff
5120
5121 // This method is run in a GC worker.
5122
5123 void
5124 G1CollectedHeap::
5125 g1_process_strong_roots(bool is_scavenging,
5126 ScanningOption so,
5127 OopClosure* scan_non_heap_roots,
5128 OopsInHeapRegionClosure* scan_rs,
5129 G1KlassScanClosure* scan_klasses,
5130 int worker_i) {
5131
5132 // First scan the strong roots
5133 double ext_roots_start = os::elapsedTime();
5134 double closure_app_time_sec = 0.0;
5135
5136 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5137
5138 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5139 // Walk the code cache/strong code roots w/o buffering, because StarTask
5140 // cannot handle unaligned oop locations.
5141 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5142
5143 process_strong_roots(false, // no scoping; this is parallel code
5144 is_scavenging, so,
5145 &buf_scan_non_heap_roots,
5146 &eager_scan_code_roots,
5147 scan_klasses
5148 );
5149
5150 // Now the CM ref_processor roots.
5151 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5152 // We need to treat the discovered reference lists of the
5153 // concurrent mark ref processor as roots and keep entries
5154 // (which are added by the marking threads) on them live
5155 // until they can be processed at the end of marking.
5156 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5157 }
5158
5159 // Finish up any enqueued closure apps (attributed as object copy time).
5160 buf_scan_non_heap_roots.done();
5161
5162 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5163
5164 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5165
5166 double ext_root_time_ms =
5167 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5168
5169 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5170
5171 // During conc marking we have to filter the per-thread SATB buffers
5172 // to make sure we remove any oops into the CSet (which will show up
5173 // as implicitly live).
5174 double satb_filtering_ms = 0.0;
5175 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5176 if (mark_in_progress()) {
5177 double satb_filter_start = os::elapsedTime();
5178
5179 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5180
5181 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5182 }
5183 }
5184 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5185
5186 // If this is an initial mark pause, and we're not scanning
5187 // the entire code cache, we need to mark the oops in the
5188 // strong code root lists for the regions that are not in
5189 // the collection set.
5190 // Note all threads participate in this set of root tasks.
5191 double mark_strong_code_roots_ms = 0.0;
5192 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5193 double mark_strong_roots_start = os::elapsedTime();
5194 mark_strong_code_roots(worker_i);
5195 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5196 }
5197 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5198
5199 // Now scan the complement of the collection set.
5200 if (scan_rs != NULL) {
5201 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5202 }
5203 _process_strong_tasks->all_tasks_completed();
5204 }
5205
5206 void
5207 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5208 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5209 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5210 }
5211
5212 // Weak Reference Processing support
5213
5214 // An always "is_alive" closure that is used to preserve referents.
5215 // If the object is non-null then it's alive. Used in the preservation
5216 // of referent objects that are pointed to by reference objects
5217 // discovered by the CM ref processor.
5218 class G1AlwaysAliveClosure: public BoolObjectClosure {
5219 G1CollectedHeap* _g1;
5220 public:
5221 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5222 bool do_object_b(oop p) {
5223 if (p != NULL) {
5224 return true;
5225 }
5226 return false;
5227 }
5228 };
5229
5230 bool G1STWIsAliveClosure::do_object_b(oop p) {
5231 // An object is reachable if it is outside the collection set,
5232 // or is inside and copied.
5233 return !_g1->obj_in_cs(p) || p->is_forwarded();
5234 }
5235
5236 // Non Copying Keep Alive closure
5237 class G1KeepAliveClosure: public OopClosure {
5238 G1CollectedHeap* _g1;
5239 public:
5240 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5241 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5242 void do_oop( oop* p) {
5243 oop obj = *p;
5244
5245 if (_g1->obj_in_cs(obj)) {
5246 assert( obj->is_forwarded(), "invariant" );
5247 *p = obj->forwardee();
5248 }
5249 }
5250 };
5251
5252 // Copying Keep Alive closure - can be called from both
5253 // serial and parallel code as long as different worker
5254 // threads utilize different G1ParScanThreadState instances
5255 // and different queues.
5256
5257 class G1CopyingKeepAliveClosure: public OopClosure {
5258 G1CollectedHeap* _g1h;
5259 OopClosure* _copy_non_heap_obj_cl;
5260 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5261 G1ParScanThreadState* _par_scan_state;
5262
5263 public:
5264 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5265 OopClosure* non_heap_obj_cl,
5266 OopsInHeapRegionClosure* metadata_obj_cl,
5267 G1ParScanThreadState* pss):
5268 _g1h(g1h),
5269 _copy_non_heap_obj_cl(non_heap_obj_cl),
5270 _copy_metadata_obj_cl(metadata_obj_cl),
5271 _par_scan_state(pss)
5272 {}
5273
5274 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5275 virtual void do_oop( oop* p) { do_oop_work(p); }
5276
5277 template <class T> void do_oop_work(T* p) {
5278 oop obj = oopDesc::load_decode_heap_oop(p);
5279
5280 if (_g1h->obj_in_cs(obj)) {
5281 // If the referent object has been forwarded (either copied
5282 // to a new location or to itself in the event of an
5283 // evacuation failure) then we need to update the reference
5284 // field and, if both reference and referent are in the G1
5285 // heap, update the RSet for the referent.
5286 //
5287 // If the referent has not been forwarded then we have to keep
5288 // it alive by policy. Therefore we have copy the referent.
5289 //
5290 // If the reference field is in the G1 heap then we can push
5291 // on the PSS queue. When the queue is drained (after each
5292 // phase of reference processing) the object and it's followers
5293 // will be copied, the reference field set to point to the
5294 // new location, and the RSet updated. Otherwise we need to
5295 // use the the non-heap or metadata closures directly to copy
5296 // the referent object and update the pointer, while avoiding
5297 // updating the RSet.
5298
5299 if (_g1h->is_in_g1_reserved(p)) {
5300 _par_scan_state->push_on_queue(p);
5301 } else {
5302 assert(!ClassLoaderDataGraph::contains((address)p),
5303 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5304 PTR_FORMAT, p));
5305 _copy_non_heap_obj_cl->do_oop(p);
5306 }
5307 }
5308 }
5309 };
5310
5311 // Serial drain queue closure. Called as the 'complete_gc'
5312 // closure for each discovered list in some of the
5313 // reference processing phases.
5314
5315 class G1STWDrainQueueClosure: public VoidClosure {
5316 protected:
5317 G1CollectedHeap* _g1h;
5318 G1ParScanThreadState* _par_scan_state;
5319
5320 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5321
5322 public:
5323 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5324 _g1h(g1h),
5325 _par_scan_state(pss)
5326 { }
5327
5328 void do_void() {
5329 G1ParScanThreadState* const pss = par_scan_state();
5330 pss->trim_queue();
5331 }
5332 };
5333
5334 // Parallel Reference Processing closures
5335
5336 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5337 // processing during G1 evacuation pauses.
5338
5339 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5340 private:
5341 G1CollectedHeap* _g1h;
5342 RefToScanQueueSet* _queues;
5343 FlexibleWorkGang* _workers;
5344 int _active_workers;
5345
5346 public:
5347 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5348 FlexibleWorkGang* workers,
5349 RefToScanQueueSet *task_queues,
5350 int n_workers) :
5351 _g1h(g1h),
5352 _queues(task_queues),
5353 _workers(workers),
5354 _active_workers(n_workers)
5355 {
5356 assert(n_workers > 0, "shouldn't call this otherwise");
5357 }
5358
5359 // Executes the given task using concurrent marking worker threads.
5360 virtual void execute(ProcessTask& task);
5361 virtual void execute(EnqueueTask& task);
5362 };
5363
5364 // Gang task for possibly parallel reference processing
5365
5366 class G1STWRefProcTaskProxy: public AbstractGangTask {
5367 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5368 ProcessTask& _proc_task;
5369 G1CollectedHeap* _g1h;
5370 RefToScanQueueSet *_task_queues;
5371 ParallelTaskTerminator* _terminator;
5372
5373 public:
5374 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5375 G1CollectedHeap* g1h,
5376 RefToScanQueueSet *task_queues,
5377 ParallelTaskTerminator* terminator) :
5378 AbstractGangTask("Process reference objects in parallel"),
5379 _proc_task(proc_task),
5380 _g1h(g1h),
5381 _task_queues(task_queues),
5382 _terminator(terminator)
5383 {}
5384
5385 virtual void work(uint worker_id) {
5386 // The reference processing task executed by a single worker.
5387 ResourceMark rm;
5388 HandleMark hm;
5389
5390 G1STWIsAliveClosure is_alive(_g1h);
5391
5392 G1ParScanThreadState pss(_g1h, worker_id);
5393
5394 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5395 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5396 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5397
5398 pss.set_evac_closure(&scan_evac_cl);
5399 pss.set_evac_failure_closure(&evac_failure_cl);
5400 pss.set_partial_scan_closure(&partial_scan_cl);
5401
5402 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5403 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5404
5405 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5406 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5407
5408 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5409 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5410
5411 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5412 // We also need to mark copied objects.
5413 copy_non_heap_cl = ©_mark_non_heap_cl;
5414 copy_metadata_cl = ©_mark_metadata_cl;
5415 }
5416
5417 // Keep alive closure.
5418 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5419
5420 // Complete GC closure
5421 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5422
5423 // Call the reference processing task's work routine.
5424 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5425
5426 // Note we cannot assert that the refs array is empty here as not all
5427 // of the processing tasks (specifically phase2 - pp2_work) execute
5428 // the complete_gc closure (which ordinarily would drain the queue) so
5429 // the queue may not be empty.
5430 }
5431 };
5432
5433 // Driver routine for parallel reference processing.
5434 // Creates an instance of the ref processing gang
5435 // task and has the worker threads execute it.
5436 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5437 assert(_workers != NULL, "Need parallel worker threads.");
5438
5439 ParallelTaskTerminator terminator(_active_workers, _queues);
5440 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5441
5442 _g1h->set_par_threads(_active_workers);
5443 _workers->run_task(&proc_task_proxy);
5444 _g1h->set_par_threads(0);
5445 }
5446
5447 // Gang task for parallel reference enqueueing.
5448
5449 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5450 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5451 EnqueueTask& _enq_task;
5452
5453 public:
5454 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5455 AbstractGangTask("Enqueue reference objects in parallel"),
5456 _enq_task(enq_task)
5457 { }
5458
5459 virtual void work(uint worker_id) {
5460 _enq_task.work(worker_id);
5461 }
5462 };
5463
5464 // Driver routine for parallel reference enqueueing.
5465 // Creates an instance of the ref enqueueing gang
5466 // task and has the worker threads execute it.
5467
5468 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5469 assert(_workers != NULL, "Need parallel worker threads.");
5470
5471 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5472
5473 _g1h->set_par_threads(_active_workers);
5474 _workers->run_task(&enq_task_proxy);
5475 _g1h->set_par_threads(0);
5476 }
5477
5478 // End of weak reference support closures
5479
5480 // Abstract task used to preserve (i.e. copy) any referent objects
5481 // that are in the collection set and are pointed to by reference
5482 // objects discovered by the CM ref processor.
5483
5484 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5485 protected:
5486 G1CollectedHeap* _g1h;
5487 RefToScanQueueSet *_queues;
5488 ParallelTaskTerminator _terminator;
5489 uint _n_workers;
5490
5491 public:
5492 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5493 AbstractGangTask("ParPreserveCMReferents"),
5494 _g1h(g1h),
5495 _queues(task_queues),
5496 _terminator(workers, _queues),
5497 _n_workers(workers)
5498 { }
5499
5500 void work(uint worker_id) {
5501 ResourceMark rm;
5502 HandleMark hm;
5503
5504 G1ParScanThreadState pss(_g1h, worker_id);
5505 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5506 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5507 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5508
5509 pss.set_evac_closure(&scan_evac_cl);
5510 pss.set_evac_failure_closure(&evac_failure_cl);
5511 pss.set_partial_scan_closure(&partial_scan_cl);
5512
5513 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5514
5515
5516 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5517 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5518
5519 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5520 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5521
5522 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5523 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5524
5525 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5526 // We also need to mark copied objects.
5527 copy_non_heap_cl = ©_mark_non_heap_cl;
5528 copy_metadata_cl = ©_mark_metadata_cl;
5529 }
5530
5531 // Is alive closure
5532 G1AlwaysAliveClosure always_alive(_g1h);
5533
5534 // Copying keep alive closure. Applied to referent objects that need
5535 // to be copied.
5536 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5537
5538 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5539
5540 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5541 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5542
5543 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5544 // So this must be true - but assert just in case someone decides to
5545 // change the worker ids.
5546 assert(0 <= worker_id && worker_id < limit, "sanity");
5547 assert(!rp->discovery_is_atomic(), "check this code");
5548
5549 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5550 for (uint idx = worker_id; idx < limit; idx += stride) {
5551 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5552
5553 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5554 while (iter.has_next()) {
5555 // Since discovery is not atomic for the CM ref processor, we
5556 // can see some null referent objects.
5557 iter.load_ptrs(DEBUG_ONLY(true));
5558 oop ref = iter.obj();
5559
5560 // This will filter nulls.
5561 if (iter.is_referent_alive()) {
5562 iter.make_referent_alive();
5563 }
5564 iter.move_to_next();
5565 }
5566 }
5567
5568 // Drain the queue - which may cause stealing
5569 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5570 drain_queue.do_void();
5571 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5572 assert(pss.refs()->is_empty(), "should be");
5573 }
5574 };
5575
5576 // Weak Reference processing during an evacuation pause (part 1).
5577 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5578 double ref_proc_start = os::elapsedTime();
5579
5580 ReferenceProcessor* rp = _ref_processor_stw;
5581 assert(rp->discovery_enabled(), "should have been enabled");
5582
5583 // Any reference objects, in the collection set, that were 'discovered'
5584 // by the CM ref processor should have already been copied (either by
5585 // applying the external root copy closure to the discovered lists, or
5586 // by following an RSet entry).
5587 //
5588 // But some of the referents, that are in the collection set, that these
5589 // reference objects point to may not have been copied: the STW ref
5590 // processor would have seen that the reference object had already
5591 // been 'discovered' and would have skipped discovering the reference,
5592 // but would not have treated the reference object as a regular oop.
5593 // As a result the copy closure would not have been applied to the
5594 // referent object.
5595 //
5596 // We need to explicitly copy these referent objects - the references
5597 // will be processed at the end of remarking.
5598 //
5599 // We also need to do this copying before we process the reference
5600 // objects discovered by the STW ref processor in case one of these
5601 // referents points to another object which is also referenced by an
5602 // object discovered by the STW ref processor.
5603
5604 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5605 no_of_gc_workers == workers()->active_workers(),
5606 "Need to reset active GC workers");
5607
5608 set_par_threads(no_of_gc_workers);
5609 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5610 no_of_gc_workers,
5611 _task_queues);
5612
5613 if (G1CollectedHeap::use_parallel_gc_threads()) {
5614 workers()->run_task(&keep_cm_referents);
5615 } else {
5616 keep_cm_referents.work(0);
5617 }
5618
5619 set_par_threads(0);
5620
5621 // Closure to test whether a referent is alive.
5622 G1STWIsAliveClosure is_alive(this);
5623
5624 // Even when parallel reference processing is enabled, the processing
5625 // of JNI refs is serial and performed serially by the current thread
5626 // rather than by a worker. The following PSS will be used for processing
5627 // JNI refs.
5628
5629 // Use only a single queue for this PSS.
5630 G1ParScanThreadState pss(this, 0);
5631
5632 // We do not embed a reference processor in the copying/scanning
5633 // closures while we're actually processing the discovered
5634 // reference objects.
5635 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5636 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5637 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5638
5639 pss.set_evac_closure(&scan_evac_cl);
5640 pss.set_evac_failure_closure(&evac_failure_cl);
5641 pss.set_partial_scan_closure(&partial_scan_cl);
5642
5643 assert(pss.refs()->is_empty(), "pre-condition");
5644
5645 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5646 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5647
5648 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5649 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5650
5651 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5652 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5653
5654 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5655 // We also need to mark copied objects.
5656 copy_non_heap_cl = ©_mark_non_heap_cl;
5657 copy_metadata_cl = ©_mark_metadata_cl;
5658 }
5659
5660 // Keep alive closure.
5661 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5662
5663 // Serial Complete GC closure
5664 G1STWDrainQueueClosure drain_queue(this, &pss);
5665
5666 // Setup the soft refs policy...
5667 rp->setup_policy(false);
5668
5669 ReferenceProcessorStats stats;
5670 if (!rp->processing_is_mt()) {
5671 // Serial reference processing...
5672 stats = rp->process_discovered_references(&is_alive,
5673 &keep_alive,
5674 &drain_queue,
5675 NULL,
5676 _gc_timer_stw);
5677 } else {
5678 // Parallel reference processing
5679 assert(rp->num_q() == no_of_gc_workers, "sanity");
5680 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5681
5682 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5683 stats = rp->process_discovered_references(&is_alive,
5684 &keep_alive,
5685 &drain_queue,
5686 &par_task_executor,
5687 _gc_timer_stw);
5688 }
5689
5690 _gc_tracer_stw->report_gc_reference_stats(stats);
5691 // We have completed copying any necessary live referent objects
5692 // (that were not copied during the actual pause) so we can
5693 // retire any active alloc buffers
5694 pss.retire_alloc_buffers();
5695 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5696
5697 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5698 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5699 }
5700
5701 // Weak Reference processing during an evacuation pause (part 2).
5702 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5703 double ref_enq_start = os::elapsedTime();
5704
5705 ReferenceProcessor* rp = _ref_processor_stw;
5706 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5707
5708 // Now enqueue any remaining on the discovered lists on to
5709 // the pending list.
5710 if (!rp->processing_is_mt()) {
5711 // Serial reference processing...
5712 rp->enqueue_discovered_references();
5713 } else {
5714 // Parallel reference enqueueing
5715
5716 assert(no_of_gc_workers == workers()->active_workers(),
5717 "Need to reset active workers");
5718 assert(rp->num_q() == no_of_gc_workers, "sanity");
5719 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5720
5721 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5722 rp->enqueue_discovered_references(&par_task_executor);
5723 }
5724
5725 rp->verify_no_references_recorded();
5726 assert(!rp->discovery_enabled(), "should have been disabled");
5727
5728 // FIXME
5729 // CM's reference processing also cleans up the string and symbol tables.
5730 // Should we do that here also? We could, but it is a serial operation
5731 // and could significantly increase the pause time.
5732
5733 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5734 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5735 }
5736
5737 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5738 _expand_heap_after_alloc_failure = true;
5739 _evacuation_failed = false;
5740
5741 // Should G1EvacuationFailureALot be in effect for this GC?
5742 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5743
5744 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5745
5746 // Disable the hot card cache.
5747 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5748 hot_card_cache->reset_hot_cache_claimed_index();
5749 hot_card_cache->set_use_cache(false);
5750
5751 uint n_workers;
5752 if (G1CollectedHeap::use_parallel_gc_threads()) {
5753 n_workers =
5754 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5755 workers()->active_workers(),
5756 Threads::number_of_non_daemon_threads());
5757 assert(UseDynamicNumberOfGCThreads ||
5758 n_workers == workers()->total_workers(),
5759 "If not dynamic should be using all the workers");
5760 workers()->set_active_workers(n_workers);
5761 set_par_threads(n_workers);
5762 } else {
5763 assert(n_par_threads() == 0,
5764 "Should be the original non-parallel value");
5765 n_workers = 1;
5766 }
5767
5768 G1ParTask g1_par_task(this, _task_queues);
5769
5770 init_for_evac_failure(NULL);
5771
5772 rem_set()->prepare_for_younger_refs_iterate(true);
5773
5774 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5775 double start_par_time_sec = os::elapsedTime();
5776 double end_par_time_sec;
5777
5778 {
5779 StrongRootsScope srs(this);
5780
5781 if (G1CollectedHeap::use_parallel_gc_threads()) {
5782 // The individual threads will set their evac-failure closures.
5783 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5784 // These tasks use ShareHeap::_process_strong_tasks
5785 assert(UseDynamicNumberOfGCThreads ||
5786 workers()->active_workers() == workers()->total_workers(),
5787 "If not dynamic should be using all the workers");
5788 workers()->run_task(&g1_par_task);
5789 } else {
5790 g1_par_task.set_for_termination(n_workers);
5791 g1_par_task.work(0);
5792 }
5793 end_par_time_sec = os::elapsedTime();
5794
5795 // Closing the inner scope will execute the destructor
5796 // for the StrongRootsScope object. We record the current
5797 // elapsed time before closing the scope so that time
5798 // taken for the SRS destructor is NOT included in the
5799 // reported parallel time.
5800 }
5801
5802 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5803 g1_policy()->phase_times()->record_par_time(par_time_ms);
5804
5805 double code_root_fixup_time_ms =
5806 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5807 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5808
5809 set_par_threads(0);
5810
5811 // Process any discovered reference objects - we have
5812 // to do this _before_ we retire the GC alloc regions
5813 // as we may have to copy some 'reachable' referent
5814 // objects (and their reachable sub-graphs) that were
5815 // not copied during the pause.
5816 process_discovered_references(n_workers);
5817
5818 // Weak root processing.
5819 {
5820 G1STWIsAliveClosure is_alive(this);
5821 G1KeepAliveClosure keep_alive(this);
5822 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5823 }
5824
5825 release_gc_alloc_regions(n_workers, evacuation_info);
5826 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5827
5828 // Reset and re-enable the hot card cache.
5829 // Note the counts for the cards in the regions in the
5830 // collection set are reset when the collection set is freed.
5831 hot_card_cache->reset_hot_cache();
5832 hot_card_cache->set_use_cache(true);
5833
5834 // Migrate the strong code roots attached to each region in
5835 // the collection set. Ideally we would like to do this
5836 // after we have finished the scanning/evacuation of the
5837 // strong code roots for a particular heap region.
5838 migrate_strong_code_roots();
5839
5840 if (g1_policy()->during_initial_mark_pause()) {
5841 // Reset the claim values set during marking the strong code roots
5842 reset_heap_region_claim_values();
5843 }
5844
5845 finalize_for_evac_failure();
5846
5847 if (evacuation_failed()) {
5848 remove_self_forwarding_pointers();
5849
5850 // Reset the G1EvacuationFailureALot counters and flags
5851 // Note: the values are reset only when an actual
5852 // evacuation failure occurs.
5853 NOT_PRODUCT(reset_evacuation_should_fail();)
5854 }
5855
5856 // Enqueue any remaining references remaining on the STW
5857 // reference processor's discovered lists. We need to do
5858 // this after the card table is cleaned (and verified) as
5859 // the act of enqueueing entries on to the pending list
5860 // will log these updates (and dirty their associated
5861 // cards). We need these updates logged to update any
5862 // RSets.
5863 enqueue_discovered_references(n_workers);
5864
5865 if (G1DeferredRSUpdate) {
5866 RedirtyLoggedCardTableEntryFastClosure redirty;
5867 dirty_card_queue_set().set_closure(&redirty);
5868 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5869
5870 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5871 dcq.merge_bufferlists(&dirty_card_queue_set());
5872 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5873 }
5874 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5875 }
5876
5877 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5878 size_t* pre_used,
5879 FreeRegionList* free_list,
5880 OldRegionSet* old_proxy_set,
5881 HumongousRegionSet* humongous_proxy_set,
5882 HRRSCleanupTask* hrrs_cleanup_task,
5883 bool par) {
5884 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5885 if (hr->isHumongous()) {
5886 assert(hr->startsHumongous(), "we should only see starts humongous");
5887 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5888 } else {
5889 _old_set.remove_with_proxy(hr, old_proxy_set);
5890 free_region(hr, pre_used, free_list, par);
5891 }
5892 } else {
5893 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5894 }
5895 }
5896
5897 void G1CollectedHeap::free_region(HeapRegion* hr,
5898 size_t* pre_used,
5899 FreeRegionList* free_list,
5900 bool par) {
5901 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5902 assert(!hr->is_empty(), "the region should not be empty");
5903 assert(free_list != NULL, "pre-condition");
5904
5905 // Clear the card counts for this region.
5906 // Note: we only need to do this if the region is not young
5907 // (since we don't refine cards in young regions).
5908 if (!hr->is_young()) {
5909 _cg1r->hot_card_cache()->reset_card_counts(hr);
5910 }
5911 *pre_used += hr->used();
5912 hr->hr_clear(par, true /* clear_space */);
5913 free_list->add_as_head(hr);
5914 }
5915
5916 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5917 size_t* pre_used,
5918 FreeRegionList* free_list,
5919 HumongousRegionSet* humongous_proxy_set,
5920 bool par) {
5921 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5922 assert(free_list != NULL, "pre-condition");
5923 assert(humongous_proxy_set != NULL, "pre-condition");
5924
5925 size_t hr_used = hr->used();
5926 size_t hr_capacity = hr->capacity();
5927 size_t hr_pre_used = 0;
5928 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5929 // We need to read this before we make the region non-humongous,
5930 // otherwise the information will be gone.
5931 uint last_index = hr->last_hc_index();
5932 hr->set_notHumongous();
5933 free_region(hr, &hr_pre_used, free_list, par);
5934
5935 uint i = hr->hrs_index() + 1;
5936 while (i < last_index) {
5937 HeapRegion* curr_hr = region_at(i);
5938 assert(curr_hr->continuesHumongous(), "invariant");
5939 curr_hr->set_notHumongous();
5940 free_region(curr_hr, &hr_pre_used, free_list, par);
5941 i += 1;
5942 }
5943 assert(hr_pre_used == hr_used,
5944 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5945 "should be the same", hr_pre_used, hr_used));
5946 *pre_used += hr_pre_used;
5947 }
5948
5949 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5950 FreeRegionList* free_list,
5951 OldRegionSet* old_proxy_set,
5952 HumongousRegionSet* humongous_proxy_set,
5953 bool par) {
5954 if (pre_used > 0) {
5955 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5956 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5957 assert(_summary_bytes_used >= pre_used,
5958 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5959 "should be >= pre_used: "SIZE_FORMAT,
5960 _summary_bytes_used, pre_used));
5961 _summary_bytes_used -= pre_used;
5962 }
5963 if (free_list != NULL && !free_list->is_empty()) {
5964 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5965 _free_list.add_as_head(free_list);
5966 }
5967 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5968 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5969 _old_set.update_from_proxy(old_proxy_set);
5970 }
5971 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5972 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5973 _humongous_set.update_from_proxy(humongous_proxy_set);
5974 }
5975 }
5976
5977 class G1ParCleanupCTTask : public AbstractGangTask {
5978 CardTableModRefBS* _ct_bs;
5979 G1CollectedHeap* _g1h;
5980 HeapRegion* volatile _su_head;
5981 public:
5982 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5983 G1CollectedHeap* g1h) :
5984 AbstractGangTask("G1 Par Cleanup CT Task"),
5985 _ct_bs(ct_bs), _g1h(g1h) { }
5986
5987 void work(uint worker_id) {
5988 HeapRegion* r;
5989 while (r = _g1h->pop_dirty_cards_region()) {
5990 clear_cards(r);
5991 }
5992 }
5993
5994 void clear_cards(HeapRegion* r) {
5995 // Cards of the survivors should have already been dirtied.
5996 if (!r->is_survivor()) {
5997 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5998 }
5999 }
6000 };
6001
6002 #ifndef PRODUCT
6003 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6004 G1CollectedHeap* _g1h;
6005 CardTableModRefBS* _ct_bs;
6006 public:
6007 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
6008 : _g1h(g1h), _ct_bs(ct_bs) { }
6009 virtual bool doHeapRegion(HeapRegion* r) {
6010 if (r->is_survivor()) {
6011 _g1h->verify_dirty_region(r);
6012 } else {
6013 _g1h->verify_not_dirty_region(r);
6014 }
6015 return false;
6016 }
6017 };
6018
6019 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6020 // All of the region should be clean.
6021 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
6022 MemRegion mr(hr->bottom(), hr->end());
6023 ct_bs->verify_not_dirty_region(mr);
6024 }
6025
6026 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6027 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6028 // dirty allocated blocks as they allocate them. The thread that
6029 // retires each region and replaces it with a new one will do a
6030 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6031 // not dirty that area (one less thing to have to do while holding
6032 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6033 // is dirty.
6034 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
6035 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6036 ct_bs->verify_dirty_region(mr);
6037 }
6038
6039 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6040 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
6041 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6042 verify_dirty_region(hr);
6043 }
6044 }
6045
6046 void G1CollectedHeap::verify_dirty_young_regions() {
6047 verify_dirty_young_list(_young_list->first_region());
6048 }
6049 #endif
6050
6051 void G1CollectedHeap::cleanUpCardTable() {
6052 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
6053 double start = os::elapsedTime();
6054
6055 {
6056 // Iterate over the dirty cards region list.
6057 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6058
6059 if (G1CollectedHeap::use_parallel_gc_threads()) {
6060 set_par_threads();
6061 workers()->run_task(&cleanup_task);
6062 set_par_threads(0);
6063 } else {
6064 while (_dirty_cards_region_list) {
6065 HeapRegion* r = _dirty_cards_region_list;
6066 cleanup_task.clear_cards(r);
6067 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6068 if (_dirty_cards_region_list == r) {
6069 // The last region.
6070 _dirty_cards_region_list = NULL;
6071 }
6072 r->set_next_dirty_cards_region(NULL);
6073 }
6074 }
6075 #ifndef PRODUCT
6076 if (G1VerifyCTCleanup || VerifyAfterGC) {
6077 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6078 heap_region_iterate(&cleanup_verifier);
6079 }
6080 #endif
6081 }
6082
6083 double elapsed = os::elapsedTime() - start;
6084 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6085 }
6086
6087 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6088 size_t pre_used = 0;
6089 FreeRegionList local_free_list("Local List for CSet Freeing");
6090
6091 double young_time_ms = 0.0;
6092 double non_young_time_ms = 0.0;
6093
6094 // Since the collection set is a superset of the the young list,
6095 // all we need to do to clear the young list is clear its
6096 // head and length, and unlink any young regions in the code below
6097 _young_list->clear();
6098
6099 G1CollectorPolicy* policy = g1_policy();
6100
6101 double start_sec = os::elapsedTime();
6102 bool non_young = true;
6103
6104 HeapRegion* cur = cs_head;
6105 int age_bound = -1;
6106 size_t rs_lengths = 0;
6107
6108 while (cur != NULL) {
6109 assert(!is_on_master_free_list(cur), "sanity");
6110 if (non_young) {
6111 if (cur->is_young()) {
6112 double end_sec = os::elapsedTime();
6113 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6114 non_young_time_ms += elapsed_ms;
6115
6116 start_sec = os::elapsedTime();
6117 non_young = false;
6118 }
6119 } else {
6120 if (!cur->is_young()) {
6121 double end_sec = os::elapsedTime();
6122 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6123 young_time_ms += elapsed_ms;
6124
6125 start_sec = os::elapsedTime();
6126 non_young = true;
6127 }
6128 }
6129
6130 rs_lengths += cur->rem_set()->occupied();
6131
6132 HeapRegion* next = cur->next_in_collection_set();
6133 assert(cur->in_collection_set(), "bad CS");
6134 cur->set_next_in_collection_set(NULL);
6135 cur->set_in_collection_set(false);
6136
6137 if (cur->is_young()) {
6138 int index = cur->young_index_in_cset();
6139 assert(index != -1, "invariant");
6140 assert((uint) index < policy->young_cset_region_length(), "invariant");
6141 size_t words_survived = _surviving_young_words[index];
6142 cur->record_surv_words_in_group(words_survived);
6143
6144 // At this point the we have 'popped' cur from the collection set
6145 // (linked via next_in_collection_set()) but it is still in the
6146 // young list (linked via next_young_region()). Clear the
6147 // _next_young_region field.
6148 cur->set_next_young_region(NULL);
6149 } else {
6150 int index = cur->young_index_in_cset();
6151 assert(index == -1, "invariant");
6152 }
6153
6154 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6155 (!cur->is_young() && cur->young_index_in_cset() == -1),
6156 "invariant" );
6157
6158 if (!cur->evacuation_failed()) {
6159 MemRegion used_mr = cur->used_region();
6160
6161 // And the region is empty.
6162 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6163 free_region(cur, &pre_used, &local_free_list, false /* par */);
6164 } else {
6165 cur->uninstall_surv_rate_group();
6166 if (cur->is_young()) {
6167 cur->set_young_index_in_cset(-1);
6168 }
6169 cur->set_not_young();
6170 cur->set_evacuation_failed(false);
6171 // The region is now considered to be old.
6172 _old_set.add(cur);
6173 evacuation_info.increment_collectionset_used_after(cur->used());
6174 }
6175 cur = next;
6176 }
6177
6178 evacuation_info.set_regions_freed(local_free_list.length());
6179 policy->record_max_rs_lengths(rs_lengths);
6180 policy->cset_regions_freed();
6181
6182 double end_sec = os::elapsedTime();
6183 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6184
6185 if (non_young) {
6186 non_young_time_ms += elapsed_ms;
6187 } else {
6188 young_time_ms += elapsed_ms;
6189 }
6190
6191 update_sets_after_freeing_regions(pre_used, &local_free_list,
6192 NULL /* old_proxy_set */,
6193 NULL /* humongous_proxy_set */,
6194 false /* par */);
6195 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6196 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6197 }
6198
6199 // This routine is similar to the above but does not record
6200 // any policy statistics or update free lists; we are abandoning
6201 // the current incremental collection set in preparation of a
6202 // full collection. After the full GC we will start to build up
6203 // the incremental collection set again.
6204 // This is only called when we're doing a full collection
6205 // and is immediately followed by the tearing down of the young list.
6206
6207 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6208 HeapRegion* cur = cs_head;
6209
6210 while (cur != NULL) {
6211 HeapRegion* next = cur->next_in_collection_set();
6212 assert(cur->in_collection_set(), "bad CS");
6213 cur->set_next_in_collection_set(NULL);
6214 cur->set_in_collection_set(false);
6215 cur->set_young_index_in_cset(-1);
6216 cur = next;
6217 }
6218 }
6219
6220 void G1CollectedHeap::set_free_regions_coming() {
6221 if (G1ConcRegionFreeingVerbose) {
6222 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6223 "setting free regions coming");
6224 }
6225
6226 assert(!free_regions_coming(), "pre-condition");
6227 _free_regions_coming = true;
6228 }
6229
6230 void G1CollectedHeap::reset_free_regions_coming() {
6231 assert(free_regions_coming(), "pre-condition");
6232
6233 {
6234 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6235 _free_regions_coming = false;
6236 SecondaryFreeList_lock->notify_all();
6237 }
6238
6239 if (G1ConcRegionFreeingVerbose) {
6240 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6241 "reset free regions coming");
6242 }
6243 }
6244
6245 void G1CollectedHeap::wait_while_free_regions_coming() {
6246 // Most of the time we won't have to wait, so let's do a quick test
6247 // first before we take the lock.
6248 if (!free_regions_coming()) {
6249 return;
6250 }
6251
6252 if (G1ConcRegionFreeingVerbose) {
6253 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6254 "waiting for free regions");
6255 }
6256
6257 {
6258 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6259 while (free_regions_coming()) {
6260 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6261 }
6262 }
6263
6264 if (G1ConcRegionFreeingVerbose) {
6265 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6266 "done waiting for free regions");
6267 }
6268 }
6269
6270 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6271 assert(heap_lock_held_for_gc(),
6272 "the heap lock should already be held by or for this thread");
6273 _young_list->push_region(hr);
6274 }
6275
6276 class NoYoungRegionsClosure: public HeapRegionClosure {
6277 private:
6278 bool _success;
6279 public:
6280 NoYoungRegionsClosure() : _success(true) { }
6281 bool doHeapRegion(HeapRegion* r) {
6282 if (r->is_young()) {
6283 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6284 r->bottom(), r->end());
6285 _success = false;
6286 }
6287 return false;
6288 }
6289 bool success() { return _success; }
6290 };
6291
6292 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6293 bool ret = _young_list->check_list_empty(check_sample);
6294
6295 if (check_heap) {
6296 NoYoungRegionsClosure closure;
6297 heap_region_iterate(&closure);
6298 ret = ret && closure.success();
6299 }
6300
6301 return ret;
6302 }
6303
6304 class TearDownRegionSetsClosure : public HeapRegionClosure {
6305 private:
6306 OldRegionSet *_old_set;
6307
6308 public:
6309 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6310
6311 bool doHeapRegion(HeapRegion* r) {
6312 if (r->is_empty()) {
6313 // We ignore empty regions, we'll empty the free list afterwards
6314 } else if (r->is_young()) {
6315 // We ignore young regions, we'll empty the young list afterwards
6316 } else if (r->isHumongous()) {
6317 // We ignore humongous regions, we're not tearing down the
6318 // humongous region set
6319 } else {
6320 // The rest should be old
6321 _old_set->remove(r);
6322 }
6323 return false;
6324 }
6325
6326 ~TearDownRegionSetsClosure() {
6327 assert(_old_set->is_empty(), "post-condition");
6328 }
6329 };
6330
6331 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6332 assert_at_safepoint(true /* should_be_vm_thread */);
6333
6334 if (!free_list_only) {
6335 TearDownRegionSetsClosure cl(&_old_set);
6336 heap_region_iterate(&cl);
6337
6338 // Need to do this after the heap iteration to be able to
6339 // recognize the young regions and ignore them during the iteration.
6340 _young_list->empty_list();
6341 }
6342 _free_list.remove_all();
6343 }
6344
6345 class RebuildRegionSetsClosure : public HeapRegionClosure {
6346 private:
6347 bool _free_list_only;
6348 OldRegionSet* _old_set;
6349 FreeRegionList* _free_list;
6350 size_t _total_used;
6351
6352 public:
6353 RebuildRegionSetsClosure(bool free_list_only,
6354 OldRegionSet* old_set, FreeRegionList* free_list) :
6355 _free_list_only(free_list_only),
6356 _old_set(old_set), _free_list(free_list), _total_used(0) {
6357 assert(_free_list->is_empty(), "pre-condition");
6358 if (!free_list_only) {
6359 assert(_old_set->is_empty(), "pre-condition");
6360 }
6361 }
6362
6363 bool doHeapRegion(HeapRegion* r) {
6364 if (r->continuesHumongous()) {
6365 return false;
6366 }
6367
6368 if (r->is_empty()) {
6369 // Add free regions to the free list
6370 _free_list->add_as_tail(r);
6371 } else if (!_free_list_only) {
6372 assert(!r->is_young(), "we should not come across young regions");
6373
6374 if (r->isHumongous()) {
6375 // We ignore humongous regions, we left the humongous set unchanged
6376 } else {
6377 // The rest should be old, add them to the old set
6378 _old_set->add(r);
6379 }
6380 _total_used += r->used();
6381 }
6382
6383 return false;
6384 }
6385
6386 size_t total_used() {
6387 return _total_used;
6388 }
6389 };
6390
6391 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6392 assert_at_safepoint(true /* should_be_vm_thread */);
6393
6394 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6395 heap_region_iterate(&cl);
6396
6397 if (!free_list_only) {
6398 _summary_bytes_used = cl.total_used();
6399 }
6400 assert(_summary_bytes_used == recalculate_used(),
6401 err_msg("inconsistent _summary_bytes_used, "
6402 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6403 _summary_bytes_used, recalculate_used()));
6404 }
6405
6406 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6407 _refine_cte_cl->set_concurrent(concurrent);
6408 }
6409
6410 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6411 HeapRegion* hr = heap_region_containing(p);
6412 if (hr == NULL) {
6413 return false;
6414 } else {
6415 return hr->is_in(p);
6416 }
6417 }
6418
6419 // Methods for the mutator alloc region
6420
6421 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6422 bool force) {
6423 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6424 assert(!force || g1_policy()->can_expand_young_list(),
6425 "if force is true we should be able to expand the young list");
6426 bool young_list_full = g1_policy()->is_young_list_full();
6427 if (force || !young_list_full) {
6428 HeapRegion* new_alloc_region = new_region(word_size,
6429 false /* do_expand */);
6430 if (new_alloc_region != NULL) {
6431 set_region_short_lived_locked(new_alloc_region);
6432 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6433 return new_alloc_region;
6434 }
6435 }
6436 return NULL;
6437 }
6438
6439 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6440 size_t allocated_bytes) {
6441 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6442 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6443
6444 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6445 _summary_bytes_used += allocated_bytes;
6446 _hr_printer.retire(alloc_region);
6447 // We update the eden sizes here, when the region is retired,
6448 // instead of when it's allocated, since this is the point that its
6449 // used space has been recored in _summary_bytes_used.
6450 g1mm()->update_eden_size();
6451 }
6452
6453 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6454 bool force) {
6455 return _g1h->new_mutator_alloc_region(word_size, force);
6456 }
6457
6458 void G1CollectedHeap::set_par_threads() {
6459 // Don't change the number of workers. Use the value previously set
6460 // in the workgroup.
6461 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6462 uint n_workers = workers()->active_workers();
6463 assert(UseDynamicNumberOfGCThreads ||
6464 n_workers == workers()->total_workers(),
6465 "Otherwise should be using the total number of workers");
6466 if (n_workers == 0) {
6467 assert(false, "Should have been set in prior evacuation pause.");
6468 n_workers = ParallelGCThreads;
6469 workers()->set_active_workers(n_workers);
6470 }
6471 set_par_threads(n_workers);
6472 }
6473
6474 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6475 size_t allocated_bytes) {
6476 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6477 }
6478
6479 // Methods for the GC alloc regions
6480
6481 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6482 uint count,
6483 GCAllocPurpose ap) {
6484 assert(FreeList_lock->owned_by_self(), "pre-condition");
6485
6486 if (count < g1_policy()->max_regions(ap)) {
6487 HeapRegion* new_alloc_region = new_region(word_size,
6488 true /* do_expand */);
6489 if (new_alloc_region != NULL) {
6490 // We really only need to do this for old regions given that we
6491 // should never scan survivors. But it doesn't hurt to do it
6492 // for survivors too.
6493 new_alloc_region->set_saved_mark();
6494 if (ap == GCAllocForSurvived) {
6495 new_alloc_region->set_survivor();
6496 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6497 } else {
6498 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6499 }
6500 bool during_im = g1_policy()->during_initial_mark_pause();
6501 new_alloc_region->note_start_of_copying(during_im);
6502 return new_alloc_region;
6503 } else {
6504 g1_policy()->note_alloc_region_limit_reached(ap);
6505 }
6506 }
6507 return NULL;
6508 }
6509
6510 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6511 size_t allocated_bytes,
6512 GCAllocPurpose ap) {
6513 bool during_im = g1_policy()->during_initial_mark_pause();
6514 alloc_region->note_end_of_copying(during_im);
6515 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6516 if (ap == GCAllocForSurvived) {
6517 young_list()->add_survivor_region(alloc_region);
6518 } else {
6519 _old_set.add(alloc_region);
6520 }
6521 _hr_printer.retire(alloc_region);
6522 }
6523
6524 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6525 bool force) {
6526 assert(!force, "not supported for GC alloc regions");
6527 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6528 }
6529
6530 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6531 size_t allocated_bytes) {
6532 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6533 GCAllocForSurvived);
6534 }
6535
6536 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6537 bool force) {
6538 assert(!force, "not supported for GC alloc regions");
6539 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6540 }
6541
6542 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6543 size_t allocated_bytes) {
6544 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6545 GCAllocForTenured);
6546 }
6547 // Heap region set verification
6548
6549 class VerifyRegionListsClosure : public HeapRegionClosure {
6550 private:
6551 FreeRegionList* _free_list;
6552 OldRegionSet* _old_set;
6553 HumongousRegionSet* _humongous_set;
6554 uint _region_count;
6555
6556 public:
6557 VerifyRegionListsClosure(OldRegionSet* old_set,
6558 HumongousRegionSet* humongous_set,
6559 FreeRegionList* free_list) :
6560 _old_set(old_set), _humongous_set(humongous_set),
6561 _free_list(free_list), _region_count(0) { }
6562
6563 uint region_count() { return _region_count; }
6564
6565 bool doHeapRegion(HeapRegion* hr) {
6566 _region_count += 1;
6567
6568 if (hr->continuesHumongous()) {
6569 return false;
6570 }
6571
6572 if (hr->is_young()) {
6573 // TODO
6574 } else if (hr->startsHumongous()) {
6575 _humongous_set->verify_next_region(hr);
6576 } else if (hr->is_empty()) {
6577 _free_list->verify_next_region(hr);
6578 } else {
6579 _old_set->verify_next_region(hr);
6580 }
6581 return false;
6582 }
6583 };
6584
6585 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6586 HeapWord* bottom) {
6587 HeapWord* end = bottom + HeapRegion::GrainWords;
6588 MemRegion mr(bottom, end);
6589 assert(_g1_reserved.contains(mr), "invariant");
6590 // This might return NULL if the allocation fails
6591 return new HeapRegion(hrs_index, _bot_shared, mr);
6592 }
6593
6594 void G1CollectedHeap::verify_region_sets() {
6595 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6596
6597 // First, check the explicit lists.
6598 _free_list.verify();
6599 {
6600 // Given that a concurrent operation might be adding regions to
6601 // the secondary free list we have to take the lock before
6602 // verifying it.
6603 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6604 _secondary_free_list.verify();
6605 }
6606 _old_set.verify();
6607 _humongous_set.verify();
6608
6609 // If a concurrent region freeing operation is in progress it will
6610 // be difficult to correctly attributed any free regions we come
6611 // across to the correct free list given that they might belong to
6612 // one of several (free_list, secondary_free_list, any local lists,
6613 // etc.). So, if that's the case we will skip the rest of the
6614 // verification operation. Alternatively, waiting for the concurrent
6615 // operation to complete will have a non-trivial effect on the GC's
6616 // operation (no concurrent operation will last longer than the
6617 // interval between two calls to verification) and it might hide
6618 // any issues that we would like to catch during testing.
6619 if (free_regions_coming()) {
6620 return;
6621 }
6622
6623 // Make sure we append the secondary_free_list on the free_list so
6624 // that all free regions we will come across can be safely
6625 // attributed to the free_list.
6626 append_secondary_free_list_if_not_empty_with_lock();
6627
6628 // Finally, make sure that the region accounting in the lists is
6629 // consistent with what we see in the heap.
6630 _old_set.verify_start();
6631 _humongous_set.verify_start();
6632 _free_list.verify_start();
6633
6634 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6635 heap_region_iterate(&cl);
6636
6637 _old_set.verify_end();
6638 _humongous_set.verify_end();
6639 _free_list.verify_end();
6640 }
6641
6642 // Optimized nmethod scanning
6643
6644 class RegisterNMethodOopClosure: public OopClosure {
6645 G1CollectedHeap* _g1h;
6646 nmethod* _nm;
6647
6648 template <class T> void do_oop_work(T* p) {
6649 T heap_oop = oopDesc::load_heap_oop(p);
6650 if (!oopDesc::is_null(heap_oop)) {
6651 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6652 HeapRegion* hr = _g1h->heap_region_containing(obj);
6653 assert(!hr->isHumongous(), "code root in humongous region?");
6654
6655 // HeapRegion::add_strong_code_root() avoids adding duplicate
6656 // entries but having duplicates is OK since we "mark" nmethods
6657 // as visited when we scan the strong code root lists during the GC.
6658 hr->add_strong_code_root(_nm);
6659 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), "add failed?");
6660 }
6661 }
6662
6663 public:
6664 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6665 _g1h(g1h), _nm(nm) {}
6666
6667 void do_oop(oop* p) { do_oop_work(p); }
6668 void do_oop(narrowOop* p) { do_oop_work(p); }
6669 };
6670
6671 class UnregisterNMethodOopClosure: public OopClosure {
6672 G1CollectedHeap* _g1h;
6673 nmethod* _nm;
6674
6675 template <class T> void do_oop_work(T* p) {
6676 T heap_oop = oopDesc::load_heap_oop(p);
6677 if (!oopDesc::is_null(heap_oop)) {
6678 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6679 HeapRegion* hr = _g1h->heap_region_containing(obj);
6680 assert(!hr->isHumongous(), "code root in humongous region?");
6681 hr->remove_strong_code_root(_nm);
6682 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), "remove failed?");
6683 }
6684 }
6685
6686 public:
6687 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6688 _g1h(g1h), _nm(nm) {}
6689
6690 void do_oop(oop* p) { do_oop_work(p); }
6691 void do_oop(narrowOop* p) { do_oop_work(p); }
6692 };
6693
6694 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6695 CollectedHeap::register_nmethod(nm);
6696
6697 guarantee(nm != NULL, "sanity");
6698 RegisterNMethodOopClosure reg_cl(this, nm);
6699 nm->oops_do(®_cl);
6700 }
6701
6702 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6703 CollectedHeap::unregister_nmethod(nm);
6704
6705 guarantee(nm != NULL, "sanity");
6706 UnregisterNMethodOopClosure reg_cl(this, nm);
6707 nm->oops_do(®_cl, true);
6708 }
6709
6710 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6711 public:
6712 bool doHeapRegion(HeapRegion *hr) {
6713 assert(!hr->isHumongous(), "humongous region in collection set?");
6714 hr->migrate_strong_code_roots();
6715 return false;
6716 }
6717 };
6718
6719 void G1CollectedHeap::migrate_strong_code_roots() {
6720 MigrateCodeRootsHeapRegionClosure cl;
6721 double migrate_start = os::elapsedTime();
6722 collection_set_iterate(&cl);
6723 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6724 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6725 }
6726
6727 // Mark all the code roots that point into regions *not* in the
6728 // collection set.
6729 //
6730 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6731 // walking the the code roots lists of regions not in the collection
6732 // set. Suppose we have an nmethod (M) that points to objects in two
6733 // separate regions - one in the collection set (R1) and one not (R2).
6734 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6735 // nmethod M when walking the code roots for R1. When we come to scan
6736 // the code roots for R2, we would see that M is already marked and it
6737 // would be skipped and the objects in R2 that are referenced from M
6738 // would not be evacuated.
6739
6740 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6741
6742 class MarkStrongCodeRootOopClosure: public OopClosure {
6743 ConcurrentMark* _cm;
6744 HeapRegion* _hr;
6745 uint _worker_id;
6746
6747 template <class T> void do_oop_work(T* p) {
6748 T heap_oop = oopDesc::load_heap_oop(p);
6749 if (!oopDesc::is_null(heap_oop)) {
6750 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6751 // Only mark objects in the region (which is assumed
6752 // to be not in the collection set).
6753 if (_hr->is_in(obj)) {
6754 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6755 }
6756 }
6757 }
6758
6759 public:
6760 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6761 _cm(cm), _hr(hr), _worker_id(worker_id) {
6762 assert(!_hr->in_collection_set(), "sanity");
6763 }
6764
6765 void do_oop(narrowOop* p) { do_oop_work(p); }
6766 void do_oop(oop* p) { do_oop_work(p); }
6767 };
6768
6769 MarkStrongCodeRootOopClosure _oop_cl;
6770
6771 public:
6772 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6773 _oop_cl(cm, hr, worker_id) {}
6774
6775 void do_code_blob(CodeBlob* cb) {
6776 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6777 if (nm != NULL) {
6778 nm->oops_do(&_oop_cl);
6779 }
6780 }
6781 };
6782
6783 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6784 G1CollectedHeap* _g1h;
6785 uint _worker_id;
6786
6787 public:
6788 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6789 _g1h(g1h), _worker_id(worker_id) {}
6790
6791 bool doHeapRegion(HeapRegion *hr) {
6792 HeapRegionRemSet* hrrs = hr->rem_set();
6793 if (hr->isHumongous()) {
6794 // Code roots should never be attached to a humongous region
6795 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
6796 return false;
6797 }
6798
6799 if (hr->in_collection_set()) {
6800 // Don't mark code roots into regions in the collection set here.
6801 // They will be marked when we scan them.
6802 return false;
6803 }
6804
6805 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6806 hr->strong_code_roots_do(&cb_cl);
6807 return false;
6808 }
6809 };
6810
6811 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6812 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6813 if (G1CollectedHeap::use_parallel_gc_threads()) {
6814 heap_region_par_iterate_chunked(&cl,
6815 worker_id,
6816 workers()->active_workers(),
6817 HeapRegion::ParMarkRootClaimValue);
6818 } else {
6819 heap_region_iterate(&cl);
6820 }
6821 }
6822
6823 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6824 G1CollectedHeap* _g1h;
6825
6826 public:
6827 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6828 _g1h(g1h) {}
6829
6830 void do_code_blob(CodeBlob* cb) {
6831 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6832 if (nm == NULL) {
6833 return;
6834 }
6835
6836 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6837 _g1h->register_nmethod(nm);
6838 }
6839 }
6840 };
6841
6842 void G1CollectedHeap::rebuild_strong_code_roots() {
6843 RebuildStrongCodeRootClosure blob_cl(this);
6844 CodeCache::blobs_do(&blob_cl);
6845 }