1 /*
2 * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
35 #include "gc_implementation/g1/g1EvacFailure.hpp"
36 #include "gc_implementation/g1/g1Log.hpp"
37 #include "gc_implementation/g1/g1MarkSweep.hpp"
38 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
39 #include "gc_implementation/g1/g1RemSet.inline.hpp"
40 #include "gc_implementation/g1/heapRegion.inline.hpp"
41 #include "gc_implementation/g1/heapRegionRemSet.hpp"
42 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
43 #include "gc_implementation/g1/vm_operations_g1.hpp"
44 #include "gc_implementation/shared/isGCActiveMark.hpp"
45 #include "memory/gcLocker.inline.hpp"
46 #include "memory/genOopClosures.inline.hpp"
47 #include "memory/generationSpec.hpp"
48 #include "memory/referenceProcessor.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "oops/oop.pcgc.inline.hpp"
51 #include "runtime/aprofiler.hpp"
52 #include "runtime/vmThread.hpp"
53
54 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
55
56 // turn it on so that the contents of the young list (scan-only /
57 // to-be-collected) are printed at "strategic" points before / during
58 // / after the collection --- this is useful for debugging
59 #define YOUNG_LIST_VERBOSE 0
60 // CURRENT STATUS
61 // This file is under construction. Search for "FIXME".
62
63 // INVARIANTS/NOTES
64 //
65 // All allocation activity covered by the G1CollectedHeap interface is
66 // serialized by acquiring the HeapLock. This happens in mem_allocate
67 // and allocate_new_tlab, which are the "entry" points to the
68 // allocation code from the rest of the JVM. (Note that this does not
69 // apply to TLAB allocation, which is not part of this interface: it
70 // is done by clients of this interface.)
71
72 // Notes on implementation of parallelism in different tasks.
73 //
74 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
75 // The number of GC workers is passed to heap_region_par_iterate_chunked().
76 // It does use run_task() which sets _n_workers in the task.
77 // G1ParTask executes g1_process_strong_roots() ->
78 // SharedHeap::process_strong_roots() which calls eventuall to
79 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
80 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
81 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
82 //
83
84 // Local to this file.
85
86 class RefineCardTableEntryClosure: public CardTableEntryClosure {
87 SuspendibleThreadSet* _sts;
88 G1RemSet* _g1rs;
89 ConcurrentG1Refine* _cg1r;
90 bool _concurrent;
91 public:
92 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
93 G1RemSet* g1rs,
94 ConcurrentG1Refine* cg1r) :
95 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
96 {}
97 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
98 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
99 // This path is executed by the concurrent refine or mutator threads,
100 // concurrently, and so we do not care if card_ptr contains references
101 // that point into the collection set.
102 assert(!oops_into_cset, "should be");
103
104 if (_concurrent && _sts->should_yield()) {
105 // Caller will actually yield.
106 return false;
107 }
108 // Otherwise, we finished successfully; return true.
109 return true;
110 }
111 void set_concurrent(bool b) { _concurrent = b; }
112 };
113
114
115 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
116 int _calls;
117 G1CollectedHeap* _g1h;
118 CardTableModRefBS* _ctbs;
119 int _histo[256];
120 public:
121 ClearLoggedCardTableEntryClosure() :
122 _calls(0)
123 {
124 _g1h = G1CollectedHeap::heap();
125 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
126 for (int i = 0; i < 256; i++) _histo[i] = 0;
127 }
128 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
129 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
130 _calls++;
131 unsigned char* ujb = (unsigned char*)card_ptr;
132 int ind = (int)(*ujb);
133 _histo[ind]++;
134 *card_ptr = -1;
135 }
136 return true;
137 }
138 int calls() { return _calls; }
139 void print_histo() {
140 gclog_or_tty->print_cr("Card table value histogram:");
141 for (int i = 0; i < 256; i++) {
142 if (_histo[i] != 0) {
143 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
144 }
145 }
146 }
147 };
148
149 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
150 int _calls;
151 G1CollectedHeap* _g1h;
152 CardTableModRefBS* _ctbs;
153 public:
154 RedirtyLoggedCardTableEntryClosure() :
155 _calls(0)
156 {
157 _g1h = G1CollectedHeap::heap();
158 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
159 }
160 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
161 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
162 _calls++;
163 *card_ptr = 0;
164 }
165 return true;
166 }
167 int calls() { return _calls; }
168 };
169
170 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
171 public:
172 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
173 *card_ptr = CardTableModRefBS::dirty_card_val();
174 return true;
175 }
176 };
177
178 YoungList::YoungList(G1CollectedHeap* g1h) :
179 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
180 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
181 guarantee(check_list_empty(false), "just making sure...");
182 }
183
184 void YoungList::push_region(HeapRegion *hr) {
185 assert(!hr->is_young(), "should not already be young");
186 assert(hr->get_next_young_region() == NULL, "cause it should!");
187
188 hr->set_next_young_region(_head);
189 _head = hr;
190
191 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
192 ++_length;
193 }
194
195 void YoungList::add_survivor_region(HeapRegion* hr) {
196 assert(hr->is_survivor(), "should be flagged as survivor region");
197 assert(hr->get_next_young_region() == NULL, "cause it should!");
198
199 hr->set_next_young_region(_survivor_head);
200 if (_survivor_head == NULL) {
201 _survivor_tail = hr;
202 }
203 _survivor_head = hr;
204 ++_survivor_length;
205 }
206
207 void YoungList::empty_list(HeapRegion* list) {
208 while (list != NULL) {
209 HeapRegion* next = list->get_next_young_region();
210 list->set_next_young_region(NULL);
211 list->uninstall_surv_rate_group();
212 list->set_not_young();
213 list = next;
214 }
215 }
216
217 void YoungList::empty_list() {
218 assert(check_list_well_formed(), "young list should be well formed");
219
220 empty_list(_head);
221 _head = NULL;
222 _length = 0;
223
224 empty_list(_survivor_head);
225 _survivor_head = NULL;
226 _survivor_tail = NULL;
227 _survivor_length = 0;
228
229 _last_sampled_rs_lengths = 0;
230
231 assert(check_list_empty(false), "just making sure...");
232 }
233
234 bool YoungList::check_list_well_formed() {
235 bool ret = true;
236
237 uint length = 0;
238 HeapRegion* curr = _head;
239 HeapRegion* last = NULL;
240 while (curr != NULL) {
241 if (!curr->is_young()) {
242 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
243 "incorrectly tagged (y: %d, surv: %d)",
244 curr->bottom(), curr->end(),
245 curr->is_young(), curr->is_survivor());
246 ret = false;
247 }
248 ++length;
249 last = curr;
250 curr = curr->get_next_young_region();
251 }
252 ret = ret && (length == _length);
253
254 if (!ret) {
255 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
256 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
257 length, _length);
258 }
259
260 return ret;
261 }
262
263 bool YoungList::check_list_empty(bool check_sample) {
264 bool ret = true;
265
266 if (_length != 0) {
267 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
268 _length);
269 ret = false;
270 }
271 if (check_sample && _last_sampled_rs_lengths != 0) {
272 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
273 ret = false;
274 }
275 if (_head != NULL) {
276 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
277 ret = false;
278 }
279 if (!ret) {
280 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
281 }
282
283 return ret;
284 }
285
286 void
287 YoungList::rs_length_sampling_init() {
288 _sampled_rs_lengths = 0;
289 _curr = _head;
290 }
291
292 bool
293 YoungList::rs_length_sampling_more() {
294 return _curr != NULL;
295 }
296
297 void
298 YoungList::rs_length_sampling_next() {
299 assert( _curr != NULL, "invariant" );
300 size_t rs_length = _curr->rem_set()->occupied();
301
302 _sampled_rs_lengths += rs_length;
303
304 // The current region may not yet have been added to the
305 // incremental collection set (it gets added when it is
306 // retired as the current allocation region).
307 if (_curr->in_collection_set()) {
308 // Update the collection set policy information for this region
309 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
310 }
311
312 _curr = _curr->get_next_young_region();
313 if (_curr == NULL) {
314 _last_sampled_rs_lengths = _sampled_rs_lengths;
315 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
316 }
317 }
318
319 void
320 YoungList::reset_auxilary_lists() {
321 guarantee( is_empty(), "young list should be empty" );
322 assert(check_list_well_formed(), "young list should be well formed");
323
324 // Add survivor regions to SurvRateGroup.
325 _g1h->g1_policy()->note_start_adding_survivor_regions();
326 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
327
328 int young_index_in_cset = 0;
329 for (HeapRegion* curr = _survivor_head;
330 curr != NULL;
331 curr = curr->get_next_young_region()) {
332 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
333
334 // The region is a non-empty survivor so let's add it to
335 // the incremental collection set for the next evacuation
336 // pause.
337 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
338 young_index_in_cset += 1;
339 }
340 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
341 _g1h->g1_policy()->note_stop_adding_survivor_regions();
342
343 _head = _survivor_head;
344 _length = _survivor_length;
345 if (_survivor_head != NULL) {
346 assert(_survivor_tail != NULL, "cause it shouldn't be");
347 assert(_survivor_length > 0, "invariant");
348 _survivor_tail->set_next_young_region(NULL);
349 }
350
351 // Don't clear the survivor list handles until the start of
352 // the next evacuation pause - we need it in order to re-tag
353 // the survivor regions from this evacuation pause as 'young'
354 // at the start of the next.
355
356 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
357
358 assert(check_list_well_formed(), "young list should be well formed");
359 }
360
361 void YoungList::print() {
362 HeapRegion* lists[] = {_head, _survivor_head};
363 const char* names[] = {"YOUNG", "SURVIVOR"};
364
365 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
366 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
367 HeapRegion *curr = lists[list];
368 if (curr == NULL)
369 gclog_or_tty->print_cr(" empty");
370 while (curr != NULL) {
371 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
372 HR_FORMAT_PARAMS(curr),
373 curr->prev_top_at_mark_start(),
374 curr->next_top_at_mark_start(),
375 curr->age_in_surv_rate_group_cond());
376 curr = curr->get_next_young_region();
377 }
378 }
379
380 gclog_or_tty->print_cr("");
381 }
382
383 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
384 {
385 // Claim the right to put the region on the dirty cards region list
386 // by installing a self pointer.
387 HeapRegion* next = hr->get_next_dirty_cards_region();
388 if (next == NULL) {
389 HeapRegion* res = (HeapRegion*)
390 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
391 NULL);
392 if (res == NULL) {
393 HeapRegion* head;
394 do {
395 // Put the region to the dirty cards region list.
396 head = _dirty_cards_region_list;
397 next = (HeapRegion*)
398 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
399 if (next == head) {
400 assert(hr->get_next_dirty_cards_region() == hr,
401 "hr->get_next_dirty_cards_region() != hr");
402 if (next == NULL) {
403 // The last region in the list points to itself.
404 hr->set_next_dirty_cards_region(hr);
405 } else {
406 hr->set_next_dirty_cards_region(next);
407 }
408 }
409 } while (next != head);
410 }
411 }
412 }
413
414 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
415 {
416 HeapRegion* head;
417 HeapRegion* hr;
418 do {
419 head = _dirty_cards_region_list;
420 if (head == NULL) {
421 return NULL;
422 }
423 HeapRegion* new_head = head->get_next_dirty_cards_region();
424 if (head == new_head) {
425 // The last region.
426 new_head = NULL;
427 }
428 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
429 head);
430 } while (hr != head);
431 assert(hr != NULL, "invariant");
432 hr->set_next_dirty_cards_region(NULL);
433 return hr;
434 }
435
436 void G1CollectedHeap::stop_conc_gc_threads() {
437 _cg1r->stop();
438 _cmThread->stop();
439 }
440
441 #ifdef ASSERT
442 // A region is added to the collection set as it is retired
443 // so an address p can point to a region which will be in the
444 // collection set but has not yet been retired. This method
445 // therefore is only accurate during a GC pause after all
446 // regions have been retired. It is used for debugging
447 // to check if an nmethod has references to objects that can
448 // be move during a partial collection. Though it can be
449 // inaccurate, it is sufficient for G1 because the conservative
450 // implementation of is_scavengable() for G1 will indicate that
451 // all nmethods must be scanned during a partial collection.
452 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
453 HeapRegion* hr = heap_region_containing(p);
454 return hr != NULL && hr->in_collection_set();
455 }
456 #endif
457
458 // Returns true if the reference points to an object that
459 // can move in an incremental collecction.
460 bool G1CollectedHeap::is_scavengable(const void* p) {
461 G1CollectedHeap* g1h = G1CollectedHeap::heap();
462 G1CollectorPolicy* g1p = g1h->g1_policy();
463 HeapRegion* hr = heap_region_containing(p);
464 if (hr == NULL) {
465 // perm gen (or null)
466 return false;
467 } else {
468 return !hr->isHumongous();
469 }
470 }
471
472 void G1CollectedHeap::check_ct_logs_at_safepoint() {
473 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
474 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
475
476 // Count the dirty cards at the start.
477 CountNonCleanMemRegionClosure count1(this);
478 ct_bs->mod_card_iterate(&count1);
479 int orig_count = count1.n();
480
481 // First clear the logged cards.
482 ClearLoggedCardTableEntryClosure clear;
483 dcqs.set_closure(&clear);
484 dcqs.apply_closure_to_all_completed_buffers();
485 dcqs.iterate_closure_all_threads(false);
486 clear.print_histo();
487
488 // Now ensure that there's no dirty cards.
489 CountNonCleanMemRegionClosure count2(this);
490 ct_bs->mod_card_iterate(&count2);
491 if (count2.n() != 0) {
492 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
493 count2.n(), orig_count);
494 }
495 guarantee(count2.n() == 0, "Card table should be clean.");
496
497 RedirtyLoggedCardTableEntryClosure redirty;
498 JavaThread::dirty_card_queue_set().set_closure(&redirty);
499 dcqs.apply_closure_to_all_completed_buffers();
500 dcqs.iterate_closure_all_threads(false);
501 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
502 clear.calls(), orig_count);
503 guarantee(redirty.calls() == clear.calls(),
504 "Or else mechanism is broken.");
505
506 CountNonCleanMemRegionClosure count3(this);
507 ct_bs->mod_card_iterate(&count3);
508 if (count3.n() != orig_count) {
509 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
510 orig_count, count3.n());
511 guarantee(count3.n() >= orig_count, "Should have restored them all.");
512 }
513
514 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
515 }
516
517 // Private class members.
518
519 G1CollectedHeap* G1CollectedHeap::_g1h;
520
521 // Private methods.
522
523 HeapRegion*
524 G1CollectedHeap::new_region_try_secondary_free_list() {
525 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
526 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
527 if (!_secondary_free_list.is_empty()) {
528 if (G1ConcRegionFreeingVerbose) {
529 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
530 "secondary_free_list has %u entries",
531 _secondary_free_list.length());
532 }
533 // It looks as if there are free regions available on the
534 // secondary_free_list. Let's move them to the free_list and try
535 // again to allocate from it.
536 append_secondary_free_list();
537
538 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
539 "empty we should have moved at least one entry to the free_list");
540 HeapRegion* res = _free_list.remove_head();
541 if (G1ConcRegionFreeingVerbose) {
542 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
543 "allocated "HR_FORMAT" from secondary_free_list",
544 HR_FORMAT_PARAMS(res));
545 }
546 return res;
547 }
548
549 // Wait here until we get notifed either when (a) there are no
550 // more free regions coming or (b) some regions have been moved on
551 // the secondary_free_list.
552 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
553 }
554
555 if (G1ConcRegionFreeingVerbose) {
556 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
557 "could not allocate from secondary_free_list");
558 }
559 return NULL;
560 }
561
562 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
563 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
564 "the only time we use this to allocate a humongous region is "
565 "when we are allocating a single humongous region");
566
567 HeapRegion* res;
568 if (G1StressConcRegionFreeing) {
569 if (!_secondary_free_list.is_empty()) {
570 if (G1ConcRegionFreeingVerbose) {
571 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
572 "forced to look at the secondary_free_list");
573 }
574 res = new_region_try_secondary_free_list();
575 if (res != NULL) {
576 return res;
577 }
578 }
579 }
580 res = _free_list.remove_head_or_null();
581 if (res == NULL) {
582 if (G1ConcRegionFreeingVerbose) {
583 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
584 "res == NULL, trying the secondary_free_list");
585 }
586 res = new_region_try_secondary_free_list();
587 }
588 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
589 // Currently, only attempts to allocate GC alloc regions set
590 // do_expand to true. So, we should only reach here during a
591 // safepoint. If this assumption changes we might have to
592 // reconsider the use of _expand_heap_after_alloc_failure.
593 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
594
595 ergo_verbose1(ErgoHeapSizing,
596 "attempt heap expansion",
597 ergo_format_reason("region allocation request failed")
598 ergo_format_byte("allocation request"),
599 word_size * HeapWordSize);
600 if (expand(word_size * HeapWordSize)) {
601 // Given that expand() succeeded in expanding the heap, and we
602 // always expand the heap by an amount aligned to the heap
603 // region size, the free list should in theory not be empty. So
604 // it would probably be OK to use remove_head(). But the extra
605 // check for NULL is unlikely to be a performance issue here (we
606 // just expanded the heap!) so let's just be conservative and
607 // use remove_head_or_null().
608 res = _free_list.remove_head_or_null();
609 } else {
610 _expand_heap_after_alloc_failure = false;
611 }
612 }
613 return res;
614 }
615
616 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
617 size_t word_size) {
618 assert(isHumongous(word_size), "word_size should be humongous");
619 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
620
621 uint first = G1_NULL_HRS_INDEX;
622 if (num_regions == 1) {
623 // Only one region to allocate, no need to go through the slower
624 // path. The caller will attempt the expasion if this fails, so
625 // let's not try to expand here too.
626 HeapRegion* hr = new_region(word_size, false /* do_expand */);
627 if (hr != NULL) {
628 first = hr->hrs_index();
629 } else {
630 first = G1_NULL_HRS_INDEX;
631 }
632 } else {
633 // We can't allocate humongous regions while cleanupComplete() is
634 // running, since some of the regions we find to be empty might not
635 // yet be added to the free list and it is not straightforward to
636 // know which list they are on so that we can remove them. Note
637 // that we only need to do this if we need to allocate more than
638 // one region to satisfy the current humongous allocation
639 // request. If we are only allocating one region we use the common
640 // region allocation code (see above).
641 wait_while_free_regions_coming();
642 append_secondary_free_list_if_not_empty_with_lock();
643
644 if (free_regions() >= num_regions) {
645 first = _hrs.find_contiguous(num_regions);
646 if (first != G1_NULL_HRS_INDEX) {
647 for (uint i = first; i < first + num_regions; ++i) {
648 HeapRegion* hr = region_at(i);
649 assert(hr->is_empty(), "sanity");
650 assert(is_on_master_free_list(hr), "sanity");
651 hr->set_pending_removal(true);
652 }
653 _free_list.remove_all_pending(num_regions);
654 }
655 }
656 }
657 return first;
658 }
659
660 HeapWord*
661 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
662 uint num_regions,
663 size_t word_size) {
664 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
665 assert(isHumongous(word_size), "word_size should be humongous");
666 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
667
668 // Index of last region in the series + 1.
669 uint last = first + num_regions;
670
671 // We need to initialize the region(s) we just discovered. This is
672 // a bit tricky given that it can happen concurrently with
673 // refinement threads refining cards on these regions and
674 // potentially wanting to refine the BOT as they are scanning
675 // those cards (this can happen shortly after a cleanup; see CR
676 // 6991377). So we have to set up the region(s) carefully and in
677 // a specific order.
678
679 // The word size sum of all the regions we will allocate.
680 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
681 assert(word_size <= word_size_sum, "sanity");
682
683 // This will be the "starts humongous" region.
684 HeapRegion* first_hr = region_at(first);
685 // The header of the new object will be placed at the bottom of
686 // the first region.
687 HeapWord* new_obj = first_hr->bottom();
688 // This will be the new end of the first region in the series that
689 // should also match the end of the last region in the seriers.
690 HeapWord* new_end = new_obj + word_size_sum;
691 // This will be the new top of the first region that will reflect
692 // this allocation.
693 HeapWord* new_top = new_obj + word_size;
694
695 // First, we need to zero the header of the space that we will be
696 // allocating. When we update top further down, some refinement
697 // threads might try to scan the region. By zeroing the header we
698 // ensure that any thread that will try to scan the region will
699 // come across the zero klass word and bail out.
700 //
701 // NOTE: It would not have been correct to have used
702 // CollectedHeap::fill_with_object() and make the space look like
703 // an int array. The thread that is doing the allocation will
704 // later update the object header to a potentially different array
705 // type and, for a very short period of time, the klass and length
706 // fields will be inconsistent. This could cause a refinement
707 // thread to calculate the object size incorrectly.
708 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
709
710 // We will set up the first region as "starts humongous". This
711 // will also update the BOT covering all the regions to reflect
712 // that there is a single object that starts at the bottom of the
713 // first region.
714 first_hr->set_startsHumongous(new_top, new_end);
715
716 // Then, if there are any, we will set up the "continues
717 // humongous" regions.
718 HeapRegion* hr = NULL;
719 for (uint i = first + 1; i < last; ++i) {
720 hr = region_at(i);
721 hr->set_continuesHumongous(first_hr);
722 }
723 // If we have "continues humongous" regions (hr != NULL), then the
724 // end of the last one should match new_end.
725 assert(hr == NULL || hr->end() == new_end, "sanity");
726
727 // Up to this point no concurrent thread would have been able to
728 // do any scanning on any region in this series. All the top
729 // fields still point to bottom, so the intersection between
730 // [bottom,top] and [card_start,card_end] will be empty. Before we
731 // update the top fields, we'll do a storestore to make sure that
732 // no thread sees the update to top before the zeroing of the
733 // object header and the BOT initialization.
734 OrderAccess::storestore();
735
736 // Now that the BOT and the object header have been initialized,
737 // we can update top of the "starts humongous" region.
738 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
739 "new_top should be in this region");
740 first_hr->set_top(new_top);
741 if (_hr_printer.is_active()) {
742 HeapWord* bottom = first_hr->bottom();
743 HeapWord* end = first_hr->orig_end();
744 if ((first + 1) == last) {
745 // the series has a single humongous region
746 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
747 } else {
748 // the series has more than one humongous regions
749 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
750 }
751 }
752
753 // Now, we will update the top fields of the "continues humongous"
754 // regions. The reason we need to do this is that, otherwise,
755 // these regions would look empty and this will confuse parts of
756 // G1. For example, the code that looks for a consecutive number
757 // of empty regions will consider them empty and try to
758 // re-allocate them. We can extend is_empty() to also include
759 // !continuesHumongous(), but it is easier to just update the top
760 // fields here. The way we set top for all regions (i.e., top ==
761 // end for all regions but the last one, top == new_top for the
762 // last one) is actually used when we will free up the humongous
763 // region in free_humongous_region().
764 hr = NULL;
765 for (uint i = first + 1; i < last; ++i) {
766 hr = region_at(i);
767 if ((i + 1) == last) {
768 // last continues humongous region
769 assert(hr->bottom() < new_top && new_top <= hr->end(),
770 "new_top should fall on this region");
771 hr->set_top(new_top);
772 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
773 } else {
774 // not last one
775 assert(new_top > hr->end(), "new_top should be above this region");
776 hr->set_top(hr->end());
777 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
778 }
779 }
780 // If we have continues humongous regions (hr != NULL), then the
781 // end of the last one should match new_end and its top should
782 // match new_top.
783 assert(hr == NULL ||
784 (hr->end() == new_end && hr->top() == new_top), "sanity");
785
786 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
787 _summary_bytes_used += first_hr->used();
788 _humongous_set.add(first_hr);
789
790 return new_obj;
791 }
792
793 // If could fit into free regions w/o expansion, try.
794 // Otherwise, if can expand, do so.
795 // Otherwise, if using ex regions might help, try with ex given back.
796 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
797 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
798
799 verify_region_sets_optional();
800
801 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
802 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
803 uint x_num = expansion_regions();
804 uint fs = _hrs.free_suffix();
805 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
806 if (first == G1_NULL_HRS_INDEX) {
807 // The only thing we can do now is attempt expansion.
808 if (fs + x_num >= num_regions) {
809 // If the number of regions we're trying to allocate for this
810 // object is at most the number of regions in the free suffix,
811 // then the call to humongous_obj_allocate_find_first() above
812 // should have succeeded and we wouldn't be here.
813 //
814 // We should only be trying to expand when the free suffix is
815 // not sufficient for the object _and_ we have some expansion
816 // room available.
817 assert(num_regions > fs, "earlier allocation should have succeeded");
818
819 ergo_verbose1(ErgoHeapSizing,
820 "attempt heap expansion",
821 ergo_format_reason("humongous allocation request failed")
822 ergo_format_byte("allocation request"),
823 word_size * HeapWordSize);
824 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
825 // Even though the heap was expanded, it might not have
826 // reached the desired size. So, we cannot assume that the
827 // allocation will succeed.
828 first = humongous_obj_allocate_find_first(num_regions, word_size);
829 }
830 }
831 }
832
833 HeapWord* result = NULL;
834 if (first != G1_NULL_HRS_INDEX) {
835 result =
836 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
837 assert(result != NULL, "it should always return a valid result");
838
839 // A successful humongous object allocation changes the used space
840 // information of the old generation so we need to recalculate the
841 // sizes and update the jstat counters here.
842 g1mm()->update_sizes();
843 }
844
845 verify_region_sets_optional();
846
847 return result;
848 }
849
850 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
851 assert_heap_not_locked_and_not_at_safepoint();
852 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
853
854 unsigned int dummy_gc_count_before;
855 return attempt_allocation(word_size, &dummy_gc_count_before);
856 }
857
858 HeapWord*
859 G1CollectedHeap::mem_allocate(size_t word_size,
860 bool* gc_overhead_limit_was_exceeded) {
861 assert_heap_not_locked_and_not_at_safepoint();
862
863 // Loop until the allocation is satisified, or unsatisfied after GC.
864 for (int try_count = 1; /* we'll return */; try_count += 1) {
865 unsigned int gc_count_before;
866
867 HeapWord* result = NULL;
868 if (!isHumongous(word_size)) {
869 result = attempt_allocation(word_size, &gc_count_before);
870 } else {
871 result = attempt_allocation_humongous(word_size, &gc_count_before);
872 }
873 if (result != NULL) {
874 return result;
875 }
876
877 // Create the garbage collection operation...
878 VM_G1CollectForAllocation op(gc_count_before, word_size);
879 // ...and get the VM thread to execute it.
880 VMThread::execute(&op);
881
882 if (op.prologue_succeeded() && op.pause_succeeded()) {
883 // If the operation was successful we'll return the result even
884 // if it is NULL. If the allocation attempt failed immediately
885 // after a Full GC, it's unlikely we'll be able to allocate now.
886 HeapWord* result = op.result();
887 if (result != NULL && !isHumongous(word_size)) {
888 // Allocations that take place on VM operations do not do any
889 // card dirtying and we have to do it here. We only have to do
890 // this for non-humongous allocations, though.
891 dirty_young_block(result, word_size);
892 }
893 return result;
894 } else {
895 assert(op.result() == NULL,
896 "the result should be NULL if the VM op did not succeed");
897 }
898
899 // Give a warning if we seem to be looping forever.
900 if ((QueuedAllocationWarningCount > 0) &&
901 (try_count % QueuedAllocationWarningCount == 0)) {
902 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
903 }
904 }
905
906 ShouldNotReachHere();
907 return NULL;
908 }
909
910 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
911 unsigned int *gc_count_before_ret) {
912 // Make sure you read the note in attempt_allocation_humongous().
913
914 assert_heap_not_locked_and_not_at_safepoint();
915 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
916 "be called for humongous allocation requests");
917
918 // We should only get here after the first-level allocation attempt
919 // (attempt_allocation()) failed to allocate.
920
921 // We will loop until a) we manage to successfully perform the
922 // allocation or b) we successfully schedule a collection which
923 // fails to perform the allocation. b) is the only case when we'll
924 // return NULL.
925 HeapWord* result = NULL;
926 for (int try_count = 1; /* we'll return */; try_count += 1) {
927 bool should_try_gc;
928 unsigned int gc_count_before;
929
930 {
931 MutexLockerEx x(Heap_lock);
932
933 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
934 false /* bot_updates */);
935 if (result != NULL) {
936 return result;
937 }
938
939 // If we reach here, attempt_allocation_locked() above failed to
940 // allocate a new region. So the mutator alloc region should be NULL.
941 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
942
943 if (GC_locker::is_active_and_needs_gc()) {
944 if (g1_policy()->can_expand_young_list()) {
945 // No need for an ergo verbose message here,
946 // can_expand_young_list() does this when it returns true.
947 result = _mutator_alloc_region.attempt_allocation_force(word_size,
948 false /* bot_updates */);
949 if (result != NULL) {
950 return result;
951 }
952 }
953 should_try_gc = false;
954 } else {
955 // The GCLocker may not be active but the GCLocker initiated
956 // GC may not yet have been performed (GCLocker::needs_gc()
957 // returns true). In this case we do not try this GC and
958 // wait until the GCLocker initiated GC is performed, and
959 // then retry the allocation.
960 if (GC_locker::needs_gc()) {
961 should_try_gc = false;
962 } else {
963 // Read the GC count while still holding the Heap_lock.
964 gc_count_before = total_collections();
965 should_try_gc = true;
966 }
967 }
968 }
969
970 if (should_try_gc) {
971 bool succeeded;
972 result = do_collection_pause(word_size, gc_count_before, &succeeded);
973 if (result != NULL) {
974 assert(succeeded, "only way to get back a non-NULL result");
975 return result;
976 }
977
978 if (succeeded) {
979 // If we get here we successfully scheduled a collection which
980 // failed to allocate. No point in trying to allocate
981 // further. We'll just return NULL.
982 MutexLockerEx x(Heap_lock);
983 *gc_count_before_ret = total_collections();
984 return NULL;
985 }
986 } else {
987 // The GCLocker is either active or the GCLocker initiated
988 // GC has not yet been performed. Stall until it is and
989 // then retry the allocation.
990 GC_locker::stall_until_clear();
991 }
992
993 // We can reach here if we were unsuccessul in scheduling a
994 // collection (because another thread beat us to it) or if we were
995 // stalled due to the GC locker. In either can we should retry the
996 // allocation attempt in case another thread successfully
997 // performed a collection and reclaimed enough space. We do the
998 // first attempt (without holding the Heap_lock) here and the
999 // follow-on attempt will be at the start of the next loop
1000 // iteration (after taking the Heap_lock).
1001 result = _mutator_alloc_region.attempt_allocation(word_size,
1002 false /* bot_updates */);
1003 if (result != NULL) {
1004 return result;
1005 }
1006
1007 // Give a warning if we seem to be looping forever.
1008 if ((QueuedAllocationWarningCount > 0) &&
1009 (try_count % QueuedAllocationWarningCount == 0)) {
1010 warning("G1CollectedHeap::attempt_allocation_slow() "
1011 "retries %d times", try_count);
1012 }
1013 }
1014
1015 ShouldNotReachHere();
1016 return NULL;
1017 }
1018
1019 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1020 unsigned int * gc_count_before_ret) {
1021 // The structure of this method has a lot of similarities to
1022 // attempt_allocation_slow(). The reason these two were not merged
1023 // into a single one is that such a method would require several "if
1024 // allocation is not humongous do this, otherwise do that"
1025 // conditional paths which would obscure its flow. In fact, an early
1026 // version of this code did use a unified method which was harder to
1027 // follow and, as a result, it had subtle bugs that were hard to
1028 // track down. So keeping these two methods separate allows each to
1029 // be more readable. It will be good to keep these two in sync as
1030 // much as possible.
1031
1032 assert_heap_not_locked_and_not_at_safepoint();
1033 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1034 "should only be called for humongous allocations");
1035
1036 // Humongous objects can exhaust the heap quickly, so we should check if we
1037 // need to start a marking cycle at each humongous object allocation. We do
1038 // the check before we do the actual allocation. The reason for doing it
1039 // before the allocation is that we avoid having to keep track of the newly
1040 // allocated memory while we do a GC.
1041 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1042 word_size)) {
1043 collect(GCCause::_g1_humongous_allocation);
1044 }
1045
1046 // We will loop until a) we manage to successfully perform the
1047 // allocation or b) we successfully schedule a collection which
1048 // fails to perform the allocation. b) is the only case when we'll
1049 // return NULL.
1050 HeapWord* result = NULL;
1051 for (int try_count = 1; /* we'll return */; try_count += 1) {
1052 bool should_try_gc;
1053 unsigned int gc_count_before;
1054
1055 {
1056 MutexLockerEx x(Heap_lock);
1057
1058 // Given that humongous objects are not allocated in young
1059 // regions, we'll first try to do the allocation without doing a
1060 // collection hoping that there's enough space in the heap.
1061 result = humongous_obj_allocate(word_size);
1062 if (result != NULL) {
1063 return result;
1064 }
1065
1066 if (GC_locker::is_active_and_needs_gc()) {
1067 should_try_gc = false;
1068 } else {
1069 // The GCLocker may not be active but the GCLocker initiated
1070 // GC may not yet have been performed (GCLocker::needs_gc()
1071 // returns true). In this case we do not try this GC and
1072 // wait until the GCLocker initiated GC is performed, and
1073 // then retry the allocation.
1074 if (GC_locker::needs_gc()) {
1075 should_try_gc = false;
1076 } else {
1077 // Read the GC count while still holding the Heap_lock.
1078 gc_count_before = total_collections();
1079 should_try_gc = true;
1080 }
1081 }
1082 }
1083
1084 if (should_try_gc) {
1085 // If we failed to allocate the humongous object, we should try to
1086 // do a collection pause (if we're allowed) in case it reclaims
1087 // enough space for the allocation to succeed after the pause.
1088
1089 bool succeeded;
1090 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1091 if (result != NULL) {
1092 assert(succeeded, "only way to get back a non-NULL result");
1093 return result;
1094 }
1095
1096 if (succeeded) {
1097 // If we get here we successfully scheduled a collection which
1098 // failed to allocate. No point in trying to allocate
1099 // further. We'll just return NULL.
1100 MutexLockerEx x(Heap_lock);
1101 *gc_count_before_ret = total_collections();
1102 return NULL;
1103 }
1104 } else {
1105 // The GCLocker is either active or the GCLocker initiated
1106 // GC has not yet been performed. Stall until it is and
1107 // then retry the allocation.
1108 GC_locker::stall_until_clear();
1109 }
1110
1111 // We can reach here if we were unsuccessul in scheduling a
1112 // collection (because another thread beat us to it) or if we were
1113 // stalled due to the GC locker. In either can we should retry the
1114 // allocation attempt in case another thread successfully
1115 // performed a collection and reclaimed enough space. Give a
1116 // warning if we seem to be looping forever.
1117
1118 if ((QueuedAllocationWarningCount > 0) &&
1119 (try_count % QueuedAllocationWarningCount == 0)) {
1120 warning("G1CollectedHeap::attempt_allocation_humongous() "
1121 "retries %d times", try_count);
1122 }
1123 }
1124
1125 ShouldNotReachHere();
1126 return NULL;
1127 }
1128
1129 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1130 bool expect_null_mutator_alloc_region) {
1131 assert_at_safepoint(true /* should_be_vm_thread */);
1132 assert(_mutator_alloc_region.get() == NULL ||
1133 !expect_null_mutator_alloc_region,
1134 "the current alloc region was unexpectedly found to be non-NULL");
1135
1136 if (!isHumongous(word_size)) {
1137 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1138 false /* bot_updates */);
1139 } else {
1140 HeapWord* result = humongous_obj_allocate(word_size);
1141 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1142 g1_policy()->set_initiate_conc_mark_if_possible();
1143 }
1144 return result;
1145 }
1146
1147 ShouldNotReachHere();
1148 }
1149
1150 class PostMCRemSetClearClosure: public HeapRegionClosure {
1151 G1CollectedHeap* _g1h;
1152 ModRefBarrierSet* _mr_bs;
1153 public:
1154 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1155 _g1h(g1h), _mr_bs(mr_bs) { }
1156 bool doHeapRegion(HeapRegion* r) {
1157 if (r->continuesHumongous()) {
1158 return false;
1159 }
1160 _g1h->reset_gc_time_stamps(r);
1161 HeapRegionRemSet* hrrs = r->rem_set();
1162 if (hrrs != NULL) hrrs->clear();
1163 // You might think here that we could clear just the cards
1164 // corresponding to the used region. But no: if we leave a dirty card
1165 // in a region we might allocate into, then it would prevent that card
1166 // from being enqueued, and cause it to be missed.
1167 // Re: the performance cost: we shouldn't be doing full GC anyway!
1168 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1169 return false;
1170 }
1171 };
1172
1173 void G1CollectedHeap::clear_rsets_post_compaction() {
1174 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1175 heap_region_iterate(&rs_clear);
1176 }
1177
1178 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1179 G1CollectedHeap* _g1h;
1180 UpdateRSOopClosure _cl;
1181 int _worker_i;
1182 public:
1183 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1184 _cl(g1->g1_rem_set(), worker_i),
1185 _worker_i(worker_i),
1186 _g1h(g1)
1187 { }
1188
1189 bool doHeapRegion(HeapRegion* r) {
1190 if (!r->continuesHumongous()) {
1191 _cl.set_from(r);
1192 r->oop_iterate(&_cl);
1193 }
1194 return false;
1195 }
1196 };
1197
1198 class ParRebuildRSTask: public AbstractGangTask {
1199 G1CollectedHeap* _g1;
1200 public:
1201 ParRebuildRSTask(G1CollectedHeap* g1)
1202 : AbstractGangTask("ParRebuildRSTask"),
1203 _g1(g1)
1204 { }
1205
1206 void work(uint worker_id) {
1207 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1208 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1209 _g1->workers()->active_workers(),
1210 HeapRegion::RebuildRSClaimValue);
1211 }
1212 };
1213
1214 class PostCompactionPrinterClosure: public HeapRegionClosure {
1215 private:
1216 G1HRPrinter* _hr_printer;
1217 public:
1218 bool doHeapRegion(HeapRegion* hr) {
1219 assert(!hr->is_young(), "not expecting to find young regions");
1220 // We only generate output for non-empty regions.
1221 if (!hr->is_empty()) {
1222 if (!hr->isHumongous()) {
1223 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1224 } else if (hr->startsHumongous()) {
1225 if (hr->region_num() == 1) {
1226 // single humongous region
1227 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1228 } else {
1229 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1230 }
1231 } else {
1232 assert(hr->continuesHumongous(), "only way to get here");
1233 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1234 }
1235 }
1236 return false;
1237 }
1238
1239 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1240 : _hr_printer(hr_printer) { }
1241 };
1242
1243 void G1CollectedHeap::print_hrs_post_compaction() {
1244 PostCompactionPrinterClosure cl(hr_printer());
1245 heap_region_iterate(&cl);
1246 }
1247
1248 bool G1CollectedHeap::do_collection(bool explicit_gc,
1249 bool clear_all_soft_refs,
1250 size_t word_size) {
1251 assert_at_safepoint(true /* should_be_vm_thread */);
1252
1253 if (GC_locker::check_active_before_gc()) {
1254 return false;
1255 }
1256
1257 SvcGCMarker sgcm(SvcGCMarker::FULL);
1258 ResourceMark rm;
1259
1260 print_heap_before_gc();
1261
1262 HRSPhaseSetter x(HRSPhaseFullGC);
1263 verify_region_sets_optional();
1264
1265 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1266 collector_policy()->should_clear_all_soft_refs();
1267
1268 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1269
1270 {
1271 IsGCActiveMark x;
1272
1273 // Timing
1274 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1275 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1276 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1277
1278 TraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, gclog_or_tty);
1279 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1280 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1281
1282 double start = os::elapsedTime();
1283 g1_policy()->record_full_collection_start();
1284
1285 // Note: When we have a more flexible GC logging framework that
1286 // allows us to add optional attributes to a GC log record we
1287 // could consider timing and reporting how long we wait in the
1288 // following two methods.
1289 wait_while_free_regions_coming();
1290 // If we start the compaction before the CM threads finish
1291 // scanning the root regions we might trip them over as we'll
1292 // be moving objects / updating references. So let's wait until
1293 // they are done. By telling them to abort, they should complete
1294 // early.
1295 _cm->root_regions()->abort();
1296 _cm->root_regions()->wait_until_scan_finished();
1297 append_secondary_free_list_if_not_empty_with_lock();
1298
1299 gc_prologue(true);
1300 increment_total_collections(true /* full gc */);
1301 increment_old_marking_cycles_started();
1302
1303 size_t g1h_prev_used = used();
1304 assert(used() == recalculate_used(), "Should be equal");
1305
1306 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1307 HandleMark hm; // Discard invalid handles created during verification
1308 gclog_or_tty->print(" VerifyBeforeGC:");
1309 prepare_for_verify();
1310 Universe::verify(/* silent */ false,
1311 /* option */ VerifyOption_G1UsePrevMarking);
1312
1313 }
1314 pre_full_gc_dump();
1315
1316 COMPILER2_PRESENT(DerivedPointerTable::clear());
1317
1318 // Disable discovery and empty the discovered lists
1319 // for the CM ref processor.
1320 ref_processor_cm()->disable_discovery();
1321 ref_processor_cm()->abandon_partial_discovery();
1322 ref_processor_cm()->verify_no_references_recorded();
1323
1324 // Abandon current iterations of concurrent marking and concurrent
1325 // refinement, if any are in progress. We have to do this before
1326 // wait_until_scan_finished() below.
1327 concurrent_mark()->abort();
1328
1329 // Make sure we'll choose a new allocation region afterwards.
1330 release_mutator_alloc_region();
1331 abandon_gc_alloc_regions();
1332 g1_rem_set()->cleanupHRRS();
1333
1334 // We should call this after we retire any currently active alloc
1335 // regions so that all the ALLOC / RETIRE events are generated
1336 // before the start GC event.
1337 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1338
1339 // We may have added regions to the current incremental collection
1340 // set between the last GC or pause and now. We need to clear the
1341 // incremental collection set and then start rebuilding it afresh
1342 // after this full GC.
1343 abandon_collection_set(g1_policy()->inc_cset_head());
1344 g1_policy()->clear_incremental_cset();
1345 g1_policy()->stop_incremental_cset_building();
1346
1347 tear_down_region_sets(false /* free_list_only */);
1348 g1_policy()->set_gcs_are_young(true);
1349
1350 // See the comments in g1CollectedHeap.hpp and
1351 // G1CollectedHeap::ref_processing_init() about
1352 // how reference processing currently works in G1.
1353
1354 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1355 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1356
1357 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1358 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1359
1360 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1361 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1362
1363 // Do collection work
1364 {
1365 HandleMark hm; // Discard invalid handles created during gc
1366 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1367 }
1368
1369 assert(free_regions() == 0, "we should not have added any free regions");
1370 rebuild_region_sets(false /* free_list_only */);
1371
1372 // Enqueue any discovered reference objects that have
1373 // not been removed from the discovered lists.
1374 ref_processor_stw()->enqueue_discovered_references();
1375
1376 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1377
1378 MemoryService::track_memory_usage();
1379
1380 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1381 HandleMark hm; // Discard invalid handles created during verification
1382 gclog_or_tty->print(" VerifyAfterGC:");
1383 prepare_for_verify();
1384 Universe::verify(/* silent */ false,
1385 /* option */ VerifyOption_G1UsePrevMarking);
1386
1387 }
1388
1389 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1390 ref_processor_stw()->verify_no_references_recorded();
1391
1392 // Note: since we've just done a full GC, concurrent
1393 // marking is no longer active. Therefore we need not
1394 // re-enable reference discovery for the CM ref processor.
1395 // That will be done at the start of the next marking cycle.
1396 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1397 ref_processor_cm()->verify_no_references_recorded();
1398
1399 reset_gc_time_stamp();
1400 // Since everything potentially moved, we will clear all remembered
1401 // sets, and clear all cards. Later we will rebuild remebered
1402 // sets. We will also reset the GC time stamps of the regions.
1403 clear_rsets_post_compaction();
1404 check_gc_time_stamps();
1405
1406 // Resize the heap if necessary.
1407 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1408
1409 if (_hr_printer.is_active()) {
1410 // We should do this after we potentially resize the heap so
1411 // that all the COMMIT / UNCOMMIT events are generated before
1412 // the end GC event.
1413
1414 print_hrs_post_compaction();
1415 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1416 }
1417
1418 if (_cg1r->use_cache()) {
1419 _cg1r->clear_and_record_card_counts();
1420 _cg1r->clear_hot_cache();
1421 }
1422
1423 // Rebuild remembered sets of all regions.
1424 if (G1CollectedHeap::use_parallel_gc_threads()) {
1425 uint n_workers =
1426 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1427 workers()->active_workers(),
1428 Threads::number_of_non_daemon_threads());
1429 assert(UseDynamicNumberOfGCThreads ||
1430 n_workers == workers()->total_workers(),
1431 "If not dynamic should be using all the workers");
1432 workers()->set_active_workers(n_workers);
1433 // Set parallel threads in the heap (_n_par_threads) only
1434 // before a parallel phase and always reset it to 0 after
1435 // the phase so that the number of parallel threads does
1436 // no get carried forward to a serial phase where there
1437 // may be code that is "possibly_parallel".
1438 set_par_threads(n_workers);
1439
1440 ParRebuildRSTask rebuild_rs_task(this);
1441 assert(check_heap_region_claim_values(
1442 HeapRegion::InitialClaimValue), "sanity check");
1443 assert(UseDynamicNumberOfGCThreads ||
1444 workers()->active_workers() == workers()->total_workers(),
1445 "Unless dynamic should use total workers");
1446 // Use the most recent number of active workers
1447 assert(workers()->active_workers() > 0,
1448 "Active workers not properly set");
1449 set_par_threads(workers()->active_workers());
1450 workers()->run_task(&rebuild_rs_task);
1451 set_par_threads(0);
1452 assert(check_heap_region_claim_values(
1453 HeapRegion::RebuildRSClaimValue), "sanity check");
1454 reset_heap_region_claim_values();
1455 } else {
1456 RebuildRSOutOfRegionClosure rebuild_rs(this);
1457 heap_region_iterate(&rebuild_rs);
1458 }
1459
1460 if (G1Log::fine()) {
1461 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1462 }
1463
1464 if (true) { // FIXME
1465 // Ask the permanent generation to adjust size for full collections
1466 perm()->compute_new_size();
1467 }
1468
1469 // Start a new incremental collection set for the next pause
1470 assert(g1_policy()->collection_set() == NULL, "must be");
1471 g1_policy()->start_incremental_cset_building();
1472
1473 // Clear the _cset_fast_test bitmap in anticipation of adding
1474 // regions to the incremental collection set for the next
1475 // evacuation pause.
1476 clear_cset_fast_test();
1477
1478 init_mutator_alloc_region();
1479
1480 double end = os::elapsedTime();
1481 g1_policy()->record_full_collection_end();
1482
1483 #ifdef TRACESPINNING
1484 ParallelTaskTerminator::print_termination_counts();
1485 #endif
1486
1487 gc_epilogue(true);
1488
1489 // Discard all rset updates
1490 JavaThread::dirty_card_queue_set().abandon_logs();
1491 assert(!G1DeferredRSUpdate
1492 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1493
1494 _young_list->reset_sampled_info();
1495 // At this point there should be no regions in the
1496 // entire heap tagged as young.
1497 assert( check_young_list_empty(true /* check_heap */),
1498 "young list should be empty at this point");
1499
1500 // Update the number of full collections that have been completed.
1501 increment_old_marking_cycles_completed(false /* concurrent */);
1502
1503 _hrs.verify_optional();
1504 verify_region_sets_optional();
1505
1506 print_heap_after_gc();
1507
1508 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1509 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1510 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1511 // before any GC notifications are raised.
1512 g1mm()->update_sizes();
1513 }
1514
1515 post_full_gc_dump();
1516
1517 return true;
1518 }
1519
1520 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1521 // do_collection() will return whether it succeeded in performing
1522 // the GC. Currently, there is no facility on the
1523 // do_full_collection() API to notify the caller than the collection
1524 // did not succeed (e.g., because it was locked out by the GC
1525 // locker). So, right now, we'll ignore the return value.
1526 bool dummy = do_collection(true, /* explicit_gc */
1527 clear_all_soft_refs,
1528 0 /* word_size */);
1529 }
1530
1531 // This code is mostly copied from TenuredGeneration.
1532 void
1533 G1CollectedHeap::
1534 resize_if_necessary_after_full_collection(size_t word_size) {
1535 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1536
1537 // Include the current allocation, if any, and bytes that will be
1538 // pre-allocated to support collections, as "used".
1539 const size_t used_after_gc = used();
1540 const size_t capacity_after_gc = capacity();
1541 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1542
1543 // This is enforced in arguments.cpp.
1544 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1545 "otherwise the code below doesn't make sense");
1546
1547 // We don't have floating point command-line arguments
1548 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1549 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1550 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1551 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1552
1553 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1554 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1555
1556 // We have to be careful here as these two calculations can overflow
1557 // 32-bit size_t's.
1558 double used_after_gc_d = (double) used_after_gc;
1559 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1560 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1561
1562 // Let's make sure that they are both under the max heap size, which
1563 // by default will make them fit into a size_t.
1564 double desired_capacity_upper_bound = (double) max_heap_size;
1565 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1566 desired_capacity_upper_bound);
1567 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1568 desired_capacity_upper_bound);
1569
1570 // We can now safely turn them into size_t's.
1571 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1572 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1573
1574 // This assert only makes sense here, before we adjust them
1575 // with respect to the min and max heap size.
1576 assert(minimum_desired_capacity <= maximum_desired_capacity,
1577 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1578 "maximum_desired_capacity = "SIZE_FORMAT,
1579 minimum_desired_capacity, maximum_desired_capacity));
1580
1581 // Should not be greater than the heap max size. No need to adjust
1582 // it with respect to the heap min size as it's a lower bound (i.e.,
1583 // we'll try to make the capacity larger than it, not smaller).
1584 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1585 // Should not be less than the heap min size. No need to adjust it
1586 // with respect to the heap max size as it's an upper bound (i.e.,
1587 // we'll try to make the capacity smaller than it, not greater).
1588 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1589
1590 if (capacity_after_gc < minimum_desired_capacity) {
1591 // Don't expand unless it's significant
1592 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1593 ergo_verbose4(ErgoHeapSizing,
1594 "attempt heap expansion",
1595 ergo_format_reason("capacity lower than "
1596 "min desired capacity after Full GC")
1597 ergo_format_byte("capacity")
1598 ergo_format_byte("occupancy")
1599 ergo_format_byte_perc("min desired capacity"),
1600 capacity_after_gc, used_after_gc,
1601 minimum_desired_capacity, (double) MinHeapFreeRatio);
1602 expand(expand_bytes);
1603
1604 // No expansion, now see if we want to shrink
1605 } else if (capacity_after_gc > maximum_desired_capacity) {
1606 // Capacity too large, compute shrinking size
1607 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1608 ergo_verbose4(ErgoHeapSizing,
1609 "attempt heap shrinking",
1610 ergo_format_reason("capacity higher than "
1611 "max desired capacity after Full GC")
1612 ergo_format_byte("capacity")
1613 ergo_format_byte("occupancy")
1614 ergo_format_byte_perc("max desired capacity"),
1615 capacity_after_gc, used_after_gc,
1616 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1617 shrink(shrink_bytes);
1618 }
1619 }
1620
1621
1622 HeapWord*
1623 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1624 bool* succeeded) {
1625 assert_at_safepoint(true /* should_be_vm_thread */);
1626
1627 *succeeded = true;
1628 // Let's attempt the allocation first.
1629 HeapWord* result =
1630 attempt_allocation_at_safepoint(word_size,
1631 false /* expect_null_mutator_alloc_region */);
1632 if (result != NULL) {
1633 assert(*succeeded, "sanity");
1634 return result;
1635 }
1636
1637 // In a G1 heap, we're supposed to keep allocation from failing by
1638 // incremental pauses. Therefore, at least for now, we'll favor
1639 // expansion over collection. (This might change in the future if we can
1640 // do something smarter than full collection to satisfy a failed alloc.)
1641 result = expand_and_allocate(word_size);
1642 if (result != NULL) {
1643 assert(*succeeded, "sanity");
1644 return result;
1645 }
1646
1647 // Expansion didn't work, we'll try to do a Full GC.
1648 bool gc_succeeded = do_collection(false, /* explicit_gc */
1649 false, /* clear_all_soft_refs */
1650 word_size);
1651 if (!gc_succeeded) {
1652 *succeeded = false;
1653 return NULL;
1654 }
1655
1656 // Retry the allocation
1657 result = attempt_allocation_at_safepoint(word_size,
1658 true /* expect_null_mutator_alloc_region */);
1659 if (result != NULL) {
1660 assert(*succeeded, "sanity");
1661 return result;
1662 }
1663
1664 // Then, try a Full GC that will collect all soft references.
1665 gc_succeeded = do_collection(false, /* explicit_gc */
1666 true, /* clear_all_soft_refs */
1667 word_size);
1668 if (!gc_succeeded) {
1669 *succeeded = false;
1670 return NULL;
1671 }
1672
1673 // Retry the allocation once more
1674 result = attempt_allocation_at_safepoint(word_size,
1675 true /* expect_null_mutator_alloc_region */);
1676 if (result != NULL) {
1677 assert(*succeeded, "sanity");
1678 return result;
1679 }
1680
1681 assert(!collector_policy()->should_clear_all_soft_refs(),
1682 "Flag should have been handled and cleared prior to this point");
1683
1684 // What else? We might try synchronous finalization later. If the total
1685 // space available is large enough for the allocation, then a more
1686 // complete compaction phase than we've tried so far might be
1687 // appropriate.
1688 assert(*succeeded, "sanity");
1689 return NULL;
1690 }
1691
1692 // Attempting to expand the heap sufficiently
1693 // to support an allocation of the given "word_size". If
1694 // successful, perform the allocation and return the address of the
1695 // allocated block, or else "NULL".
1696
1697 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1698 assert_at_safepoint(true /* should_be_vm_thread */);
1699
1700 verify_region_sets_optional();
1701
1702 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1703 ergo_verbose1(ErgoHeapSizing,
1704 "attempt heap expansion",
1705 ergo_format_reason("allocation request failed")
1706 ergo_format_byte("allocation request"),
1707 word_size * HeapWordSize);
1708 if (expand(expand_bytes)) {
1709 _hrs.verify_optional();
1710 verify_region_sets_optional();
1711 return attempt_allocation_at_safepoint(word_size,
1712 false /* expect_null_mutator_alloc_region */);
1713 }
1714 return NULL;
1715 }
1716
1717 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1718 HeapWord* new_end) {
1719 assert(old_end != new_end, "don't call this otherwise");
1720 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1721
1722 // Update the committed mem region.
1723 _g1_committed.set_end(new_end);
1724 // Tell the card table about the update.
1725 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1726 // Tell the BOT about the update.
1727 _bot_shared->resize(_g1_committed.word_size());
1728 }
1729
1730 bool G1CollectedHeap::expand(size_t expand_bytes) {
1731 size_t old_mem_size = _g1_storage.committed_size();
1732 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1733 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1734 HeapRegion::GrainBytes);
1735 ergo_verbose2(ErgoHeapSizing,
1736 "expand the heap",
1737 ergo_format_byte("requested expansion amount")
1738 ergo_format_byte("attempted expansion amount"),
1739 expand_bytes, aligned_expand_bytes);
1740
1741 // First commit the memory.
1742 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1743 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1744 if (successful) {
1745 // Then propagate this update to the necessary data structures.
1746 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1747 update_committed_space(old_end, new_end);
1748
1749 FreeRegionList expansion_list("Local Expansion List");
1750 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1751 assert(mr.start() == old_end, "post-condition");
1752 // mr might be a smaller region than what was requested if
1753 // expand_by() was unable to allocate the HeapRegion instances
1754 assert(mr.end() <= new_end, "post-condition");
1755
1756 size_t actual_expand_bytes = mr.byte_size();
1757 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1758 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1759 "post-condition");
1760 if (actual_expand_bytes < aligned_expand_bytes) {
1761 // We could not expand _hrs to the desired size. In this case we
1762 // need to shrink the committed space accordingly.
1763 assert(mr.end() < new_end, "invariant");
1764
1765 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1766 // First uncommit the memory.
1767 _g1_storage.shrink_by(diff_bytes);
1768 // Then propagate this update to the necessary data structures.
1769 update_committed_space(new_end, mr.end());
1770 }
1771 _free_list.add_as_tail(&expansion_list);
1772
1773 if (_hr_printer.is_active()) {
1774 HeapWord* curr = mr.start();
1775 while (curr < mr.end()) {
1776 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1777 _hr_printer.commit(curr, curr_end);
1778 curr = curr_end;
1779 }
1780 assert(curr == mr.end(), "post-condition");
1781 }
1782 g1_policy()->record_new_heap_size(n_regions());
1783 } else {
1784 ergo_verbose0(ErgoHeapSizing,
1785 "did not expand the heap",
1786 ergo_format_reason("heap expansion operation failed"));
1787 // The expansion of the virtual storage space was unsuccessful.
1788 // Let's see if it was because we ran out of swap.
1789 if (G1ExitOnExpansionFailure &&
1790 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1791 // We had head room...
1792 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1793 }
1794 }
1795 return successful;
1796 }
1797
1798 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1799 size_t old_mem_size = _g1_storage.committed_size();
1800 size_t aligned_shrink_bytes =
1801 ReservedSpace::page_align_size_down(shrink_bytes);
1802 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1803 HeapRegion::GrainBytes);
1804 uint num_regions_deleted = 0;
1805 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1806 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1807 assert(mr.end() == old_end, "post-condition");
1808
1809 ergo_verbose3(ErgoHeapSizing,
1810 "shrink the heap",
1811 ergo_format_byte("requested shrinking amount")
1812 ergo_format_byte("aligned shrinking amount")
1813 ergo_format_byte("attempted shrinking amount"),
1814 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1815 if (mr.byte_size() > 0) {
1816 if (_hr_printer.is_active()) {
1817 HeapWord* curr = mr.end();
1818 while (curr > mr.start()) {
1819 HeapWord* curr_end = curr;
1820 curr -= HeapRegion::GrainWords;
1821 _hr_printer.uncommit(curr, curr_end);
1822 }
1823 assert(curr == mr.start(), "post-condition");
1824 }
1825
1826 _g1_storage.shrink_by(mr.byte_size());
1827 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1828 assert(mr.start() == new_end, "post-condition");
1829
1830 _expansion_regions += num_regions_deleted;
1831 update_committed_space(old_end, new_end);
1832 HeapRegionRemSet::shrink_heap(n_regions());
1833 g1_policy()->record_new_heap_size(n_regions());
1834 } else {
1835 ergo_verbose0(ErgoHeapSizing,
1836 "did not shrink the heap",
1837 ergo_format_reason("heap shrinking operation failed"));
1838 }
1839 }
1840
1841 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1842 verify_region_sets_optional();
1843
1844 // We should only reach here at the end of a Full GC which means we
1845 // should not not be holding to any GC alloc regions. The method
1846 // below will make sure of that and do any remaining clean up.
1847 abandon_gc_alloc_regions();
1848
1849 // Instead of tearing down / rebuilding the free lists here, we
1850 // could instead use the remove_all_pending() method on free_list to
1851 // remove only the ones that we need to remove.
1852 tear_down_region_sets(true /* free_list_only */);
1853 shrink_helper(shrink_bytes);
1854 rebuild_region_sets(true /* free_list_only */);
1855
1856 _hrs.verify_optional();
1857 verify_region_sets_optional();
1858 }
1859
1860 // Public methods.
1861
1862 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1863 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1864 #endif // _MSC_VER
1865
1866
1867 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1868 SharedHeap(policy_),
1869 _g1_policy(policy_),
1870 _dirty_card_queue_set(false),
1871 _into_cset_dirty_card_queue_set(false),
1872 _is_alive_closure_cm(this),
1873 _is_alive_closure_stw(this),
1874 _ref_processor_cm(NULL),
1875 _ref_processor_stw(NULL),
1876 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1877 _bot_shared(NULL),
1878 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1879 _evac_failure_scan_stack(NULL) ,
1880 _mark_in_progress(false),
1881 _cg1r(NULL), _summary_bytes_used(0),
1882 _g1mm(NULL),
1883 _refine_cte_cl(NULL),
1884 _full_collection(false),
1885 _free_list("Master Free List"),
1886 _secondary_free_list("Secondary Free List"),
1887 _old_set("Old Set"),
1888 _humongous_set("Master Humongous Set"),
1889 _free_regions_coming(false),
1890 _young_list(new YoungList(this)),
1891 _gc_time_stamp(0),
1892 _retained_old_gc_alloc_region(NULL),
1893 _expand_heap_after_alloc_failure(true),
1894 _surviving_young_words(NULL),
1895 _old_marking_cycles_started(0),
1896 _old_marking_cycles_completed(0),
1897 _in_cset_fast_test(NULL),
1898 _in_cset_fast_test_base(NULL),
1899 _dirty_cards_region_list(NULL),
1900 _worker_cset_start_region(NULL),
1901 _worker_cset_start_region_time_stamp(NULL) {
1902 _g1h = this; // To catch bugs.
1903 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1904 vm_exit_during_initialization("Failed necessary allocation.");
1905 }
1906
1907 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1908
1909 int n_queues = MAX2((int)ParallelGCThreads, 1);
1910 _task_queues = new RefToScanQueueSet(n_queues);
1911
1912 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1913 assert(n_rem_sets > 0, "Invariant.");
1914
1915 HeapRegionRemSetIterator** iter_arr =
1916 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1917 for (int i = 0; i < n_queues; i++) {
1918 iter_arr[i] = new HeapRegionRemSetIterator();
1919 }
1920 _rem_set_iterator = iter_arr;
1921
1922 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues);
1923 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues);
1924
1925 for (int i = 0; i < n_queues; i++) {
1926 RefToScanQueue* q = new RefToScanQueue();
1927 q->initialize();
1928 _task_queues->register_queue(i, q);
1929 }
1930
1931 clear_cset_start_regions();
1932
1933 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1934 }
1935
1936 jint G1CollectedHeap::initialize() {
1937 CollectedHeap::pre_initialize();
1938 os::enable_vtime();
1939
1940 G1Log::init();
1941
1942 // Necessary to satisfy locking discipline assertions.
1943
1944 MutexLocker x(Heap_lock);
1945
1946 // We have to initialize the printer before committing the heap, as
1947 // it will be used then.
1948 _hr_printer.set_active(G1PrintHeapRegions);
1949
1950 // While there are no constraints in the GC code that HeapWordSize
1951 // be any particular value, there are multiple other areas in the
1952 // system which believe this to be true (e.g. oop->object_size in some
1953 // cases incorrectly returns the size in wordSize units rather than
1954 // HeapWordSize).
1955 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1956
1957 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1958 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1959
1960 // Ensure that the sizes are properly aligned.
1961 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1962 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1963
1964 _cg1r = new ConcurrentG1Refine();
1965
1966 // Reserve the maximum.
1967 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1968 // Includes the perm-gen.
1969
1970 // When compressed oops are enabled, the preferred heap base
1971 // is calculated by subtracting the requested size from the
1972 // 32Gb boundary and using the result as the base address for
1973 // heap reservation. If the requested size is not aligned to
1974 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1975 // into the ReservedHeapSpace constructor) then the actual
1976 // base of the reserved heap may end up differing from the
1977 // address that was requested (i.e. the preferred heap base).
1978 // If this happens then we could end up using a non-optimal
1979 // compressed oops mode.
1980
1981 // Since max_byte_size is aligned to the size of a heap region (checked
1982 // above), we also need to align the perm gen size as it might not be.
1983 const size_t total_reserved = max_byte_size +
1984 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1985 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1986
1987 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1988
1989 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1990 UseLargePages, addr);
1991
1992 if (UseCompressedOops) {
1993 if (addr != NULL && !heap_rs.is_reserved()) {
1994 // Failed to reserve at specified address - the requested memory
1995 // region is taken already, for example, by 'java' launcher.
1996 // Try again to reserver heap higher.
1997 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1998
1999 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
2000 UseLargePages, addr);
2001
2002 if (addr != NULL && !heap_rs0.is_reserved()) {
2003 // Failed to reserve at specified address again - give up.
2004 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
2005 assert(addr == NULL, "");
2006
2007 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
2008 UseLargePages, addr);
2009 heap_rs = heap_rs1;
2010 } else {
2011 heap_rs = heap_rs0;
2012 }
2013 }
2014 }
2015
2016 if (!heap_rs.is_reserved()) {
2017 vm_exit_during_initialization("Could not reserve enough space for object heap");
2018 return JNI_ENOMEM;
2019 }
2020
2021 // It is important to do this in a way such that concurrent readers can't
2022 // temporarily think somethings in the heap. (I've actually seen this
2023 // happen in asserts: DLD.)
2024 _reserved.set_word_size(0);
2025 _reserved.set_start((HeapWord*)heap_rs.base());
2026 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2027
2028 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2029
2030 // Create the gen rem set (and barrier set) for the entire reserved region.
2031 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2032 set_barrier_set(rem_set()->bs());
2033 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2034 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2035 } else {
2036 vm_exit_during_initialization("G1 requires a mod ref bs.");
2037 return JNI_ENOMEM;
2038 }
2039
2040 // Also create a G1 rem set.
2041 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2042 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2043 } else {
2044 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2045 return JNI_ENOMEM;
2046 }
2047
2048 // Carve out the G1 part of the heap.
2049
2050 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2051 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2052 g1_rs.size()/HeapWordSize);
2053 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
2054
2055 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2056
2057 _g1_storage.initialize(g1_rs, 0);
2058 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2059 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2060 (HeapWord*) _g1_reserved.end(),
2061 _expansion_regions);
2062
2063 // 6843694 - ensure that the maximum region index can fit
2064 // in the remembered set structures.
2065 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2066 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2067
2068 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2069 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2070 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2071 "too many cards per region");
2072
2073 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2074
2075 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2076 heap_word_size(init_byte_size));
2077
2078 _g1h = this;
2079
2080 _in_cset_fast_test_length = max_regions();
2081 _in_cset_fast_test_base =
2082 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length);
2083
2084 // We're biasing _in_cset_fast_test to avoid subtracting the
2085 // beginning of the heap every time we want to index; basically
2086 // it's the same with what we do with the card table.
2087 _in_cset_fast_test = _in_cset_fast_test_base -
2088 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2089
2090 // Clear the _cset_fast_test bitmap in anticipation of adding
2091 // regions to the incremental collection set for the first
2092 // evacuation pause.
2093 clear_cset_fast_test();
2094
2095 // Create the ConcurrentMark data structure and thread.
2096 // (Must do this late, so that "max_regions" is defined.)
2097 _cm = new ConcurrentMark(heap_rs, max_regions());
2098 _cmThread = _cm->cmThread();
2099
2100 // Initialize the from_card cache structure of HeapRegionRemSet.
2101 HeapRegionRemSet::init_heap(max_regions());
2102
2103 // Now expand into the initial heap size.
2104 if (!expand(init_byte_size)) {
2105 vm_exit_during_initialization("Failed to allocate initial heap.");
2106 return JNI_ENOMEM;
2107 }
2108
2109 // Perform any initialization actions delegated to the policy.
2110 g1_policy()->init();
2111
2112 _refine_cte_cl =
2113 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2114 g1_rem_set(),
2115 concurrent_g1_refine());
2116 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2117
2118 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2119 SATB_Q_FL_lock,
2120 G1SATBProcessCompletedThreshold,
2121 Shared_SATB_Q_lock);
2122
2123 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2124 DirtyCardQ_FL_lock,
2125 concurrent_g1_refine()->yellow_zone(),
2126 concurrent_g1_refine()->red_zone(),
2127 Shared_DirtyCardQ_lock);
2128
2129 if (G1DeferredRSUpdate) {
2130 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2131 DirtyCardQ_FL_lock,
2132 -1, // never trigger processing
2133 -1, // no limit on length
2134 Shared_DirtyCardQ_lock,
2135 &JavaThread::dirty_card_queue_set());
2136 }
2137
2138 // Initialize the card queue set used to hold cards containing
2139 // references into the collection set.
2140 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2141 DirtyCardQ_FL_lock,
2142 -1, // never trigger processing
2143 -1, // no limit on length
2144 Shared_DirtyCardQ_lock,
2145 &JavaThread::dirty_card_queue_set());
2146
2147 // In case we're keeping closure specialization stats, initialize those
2148 // counts and that mechanism.
2149 SpecializationStats::clear();
2150
2151 // Do later initialization work for concurrent refinement.
2152 _cg1r->init();
2153
2154 // Here we allocate the dummy full region that is required by the
2155 // G1AllocRegion class. If we don't pass an address in the reserved
2156 // space here, lots of asserts fire.
2157
2158 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2159 _g1_reserved.start());
2160 // We'll re-use the same region whether the alloc region will
2161 // require BOT updates or not and, if it doesn't, then a non-young
2162 // region will complain that it cannot support allocations without
2163 // BOT updates. So we'll tag the dummy region as young to avoid that.
2164 dummy_region->set_young();
2165 // Make sure it's full.
2166 dummy_region->set_top(dummy_region->end());
2167 G1AllocRegion::setup(this, dummy_region);
2168
2169 init_mutator_alloc_region();
2170
2171 // Do create of the monitoring and management support so that
2172 // values in the heap have been properly initialized.
2173 _g1mm = new G1MonitoringSupport(this);
2174
2175 return JNI_OK;
2176 }
2177
2178 void G1CollectedHeap::ref_processing_init() {
2179 // Reference processing in G1 currently works as follows:
2180 //
2181 // * There are two reference processor instances. One is
2182 // used to record and process discovered references
2183 // during concurrent marking; the other is used to
2184 // record and process references during STW pauses
2185 // (both full and incremental).
2186 // * Both ref processors need to 'span' the entire heap as
2187 // the regions in the collection set may be dotted around.
2188 //
2189 // * For the concurrent marking ref processor:
2190 // * Reference discovery is enabled at initial marking.
2191 // * Reference discovery is disabled and the discovered
2192 // references processed etc during remarking.
2193 // * Reference discovery is MT (see below).
2194 // * Reference discovery requires a barrier (see below).
2195 // * Reference processing may or may not be MT
2196 // (depending on the value of ParallelRefProcEnabled
2197 // and ParallelGCThreads).
2198 // * A full GC disables reference discovery by the CM
2199 // ref processor and abandons any entries on it's
2200 // discovered lists.
2201 //
2202 // * For the STW processor:
2203 // * Non MT discovery is enabled at the start of a full GC.
2204 // * Processing and enqueueing during a full GC is non-MT.
2205 // * During a full GC, references are processed after marking.
2206 //
2207 // * Discovery (may or may not be MT) is enabled at the start
2208 // of an incremental evacuation pause.
2209 // * References are processed near the end of a STW evacuation pause.
2210 // * For both types of GC:
2211 // * Discovery is atomic - i.e. not concurrent.
2212 // * Reference discovery will not need a barrier.
2213
2214 SharedHeap::ref_processing_init();
2215 MemRegion mr = reserved_region();
2216
2217 // Concurrent Mark ref processor
2218 _ref_processor_cm =
2219 new ReferenceProcessor(mr, // span
2220 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2221 // mt processing
2222 (int) ParallelGCThreads,
2223 // degree of mt processing
2224 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2225 // mt discovery
2226 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2227 // degree of mt discovery
2228 false,
2229 // Reference discovery is not atomic
2230 &_is_alive_closure_cm,
2231 // is alive closure
2232 // (for efficiency/performance)
2233 true);
2234 // Setting next fields of discovered
2235 // lists requires a barrier.
2236
2237 // STW ref processor
2238 _ref_processor_stw =
2239 new ReferenceProcessor(mr, // span
2240 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2241 // mt processing
2242 MAX2((int)ParallelGCThreads, 1),
2243 // degree of mt processing
2244 (ParallelGCThreads > 1),
2245 // mt discovery
2246 MAX2((int)ParallelGCThreads, 1),
2247 // degree of mt discovery
2248 true,
2249 // Reference discovery is atomic
2250 &_is_alive_closure_stw,
2251 // is alive closure
2252 // (for efficiency/performance)
2253 false);
2254 // Setting next fields of discovered
2255 // lists requires a barrier.
2256 }
2257
2258 size_t G1CollectedHeap::capacity() const {
2259 return _g1_committed.byte_size();
2260 }
2261
2262 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2263 assert(!hr->continuesHumongous(), "pre-condition");
2264 hr->reset_gc_time_stamp();
2265 if (hr->startsHumongous()) {
2266 uint first_index = hr->hrs_index() + 1;
2267 uint last_index = hr->last_hc_index();
2268 for (uint i = first_index; i < last_index; i += 1) {
2269 HeapRegion* chr = region_at(i);
2270 assert(chr->continuesHumongous(), "sanity");
2271 chr->reset_gc_time_stamp();
2272 }
2273 }
2274 }
2275
2276 #ifndef PRODUCT
2277 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2278 private:
2279 unsigned _gc_time_stamp;
2280 bool _failures;
2281
2282 public:
2283 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2284 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2285
2286 virtual bool doHeapRegion(HeapRegion* hr) {
2287 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2288 if (_gc_time_stamp != region_gc_time_stamp) {
2289 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2290 "expected %d", HR_FORMAT_PARAMS(hr),
2291 region_gc_time_stamp, _gc_time_stamp);
2292 _failures = true;
2293 }
2294 return false;
2295 }
2296
2297 bool failures() { return _failures; }
2298 };
2299
2300 void G1CollectedHeap::check_gc_time_stamps() {
2301 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2302 heap_region_iterate(&cl);
2303 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2304 }
2305 #endif // PRODUCT
2306
2307 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2308 DirtyCardQueue* into_cset_dcq,
2309 bool concurrent,
2310 int worker_i) {
2311 // Clean cards in the hot card cache
2312 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2313
2314 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2315 int n_completed_buffers = 0;
2316 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2317 n_completed_buffers++;
2318 }
2319 g1_policy()->record_update_rs_processed_buffers(worker_i,
2320 (double) n_completed_buffers);
2321 dcqs.clear_n_completed_buffers();
2322 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2323 }
2324
2325
2326 // Computes the sum of the storage used by the various regions.
2327
2328 size_t G1CollectedHeap::used() const {
2329 assert(Heap_lock->owner() != NULL,
2330 "Should be owned on this thread's behalf.");
2331 size_t result = _summary_bytes_used;
2332 // Read only once in case it is set to NULL concurrently
2333 HeapRegion* hr = _mutator_alloc_region.get();
2334 if (hr != NULL)
2335 result += hr->used();
2336 return result;
2337 }
2338
2339 size_t G1CollectedHeap::used_unlocked() const {
2340 size_t result = _summary_bytes_used;
2341 return result;
2342 }
2343
2344 class SumUsedClosure: public HeapRegionClosure {
2345 size_t _used;
2346 public:
2347 SumUsedClosure() : _used(0) {}
2348 bool doHeapRegion(HeapRegion* r) {
2349 if (!r->continuesHumongous()) {
2350 _used += r->used();
2351 }
2352 return false;
2353 }
2354 size_t result() { return _used; }
2355 };
2356
2357 size_t G1CollectedHeap::recalculate_used() const {
2358 SumUsedClosure blk;
2359 heap_region_iterate(&blk);
2360 return blk.result();
2361 }
2362
2363 size_t G1CollectedHeap::unsafe_max_alloc() {
2364 if (free_regions() > 0) return HeapRegion::GrainBytes;
2365 // otherwise, is there space in the current allocation region?
2366
2367 // We need to store the current allocation region in a local variable
2368 // here. The problem is that this method doesn't take any locks and
2369 // there may be other threads which overwrite the current allocation
2370 // region field. attempt_allocation(), for example, sets it to NULL
2371 // and this can happen *after* the NULL check here but before the call
2372 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2373 // to be a problem in the optimized build, since the two loads of the
2374 // current allocation region field are optimized away.
2375 HeapRegion* hr = _mutator_alloc_region.get();
2376 if (hr == NULL) {
2377 return 0;
2378 }
2379 return hr->free();
2380 }
2381
2382 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2383 switch (cause) {
2384 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2385 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2386 case GCCause::_g1_humongous_allocation: return true;
2387 default: return false;
2388 }
2389 }
2390
2391 #ifndef PRODUCT
2392 void G1CollectedHeap::allocate_dummy_regions() {
2393 // Let's fill up most of the region
2394 size_t word_size = HeapRegion::GrainWords - 1024;
2395 // And as a result the region we'll allocate will be humongous.
2396 guarantee(isHumongous(word_size), "sanity");
2397
2398 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2399 // Let's use the existing mechanism for the allocation
2400 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2401 if (dummy_obj != NULL) {
2402 MemRegion mr(dummy_obj, word_size);
2403 CollectedHeap::fill_with_object(mr);
2404 } else {
2405 // If we can't allocate once, we probably cannot allocate
2406 // again. Let's get out of the loop.
2407 break;
2408 }
2409 }
2410 }
2411 #endif // !PRODUCT
2412
2413 void G1CollectedHeap::increment_old_marking_cycles_started() {
2414 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2415 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2416 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2417 _old_marking_cycles_started, _old_marking_cycles_completed));
2418
2419 _old_marking_cycles_started++;
2420 }
2421
2422 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2423 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2424
2425 // We assume that if concurrent == true, then the caller is a
2426 // concurrent thread that was joined the Suspendible Thread
2427 // Set. If there's ever a cheap way to check this, we should add an
2428 // assert here.
2429
2430 // Given that this method is called at the end of a Full GC or of a
2431 // concurrent cycle, and those can be nested (i.e., a Full GC can
2432 // interrupt a concurrent cycle), the number of full collections
2433 // completed should be either one (in the case where there was no
2434 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2435 // behind the number of full collections started.
2436
2437 // This is the case for the inner caller, i.e. a Full GC.
2438 assert(concurrent ||
2439 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2440 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2441 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2442 "is inconsistent with _old_marking_cycles_completed = %u",
2443 _old_marking_cycles_started, _old_marking_cycles_completed));
2444
2445 // This is the case for the outer caller, i.e. the concurrent cycle.
2446 assert(!concurrent ||
2447 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2448 err_msg("for outer caller (concurrent cycle): "
2449 "_old_marking_cycles_started = %u "
2450 "is inconsistent with _old_marking_cycles_completed = %u",
2451 _old_marking_cycles_started, _old_marking_cycles_completed));
2452
2453 _old_marking_cycles_completed += 1;
2454
2455 // We need to clear the "in_progress" flag in the CM thread before
2456 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2457 // is set) so that if a waiter requests another System.gc() it doesn't
2458 // incorrectly see that a marking cyle is still in progress.
2459 if (concurrent) {
2460 _cmThread->clear_in_progress();
2461 }
2462
2463 // This notify_all() will ensure that a thread that called
2464 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2465 // and it's waiting for a full GC to finish will be woken up. It is
2466 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2467 FullGCCount_lock->notify_all();
2468 }
2469
2470 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2471 assert_at_safepoint(true /* should_be_vm_thread */);
2472 GCCauseSetter gcs(this, cause);
2473 switch (cause) {
2474 case GCCause::_heap_inspection:
2475 case GCCause::_heap_dump: {
2476 HandleMark hm;
2477 do_full_collection(false); // don't clear all soft refs
2478 break;
2479 }
2480 default: // XXX FIX ME
2481 ShouldNotReachHere(); // Unexpected use of this function
2482 }
2483 }
2484
2485 void G1CollectedHeap::collect(GCCause::Cause cause) {
2486 assert_heap_not_locked();
2487
2488 unsigned int gc_count_before;
2489 unsigned int old_marking_count_before;
2490 bool retry_gc;
2491
2492 do {
2493 retry_gc = false;
2494
2495 {
2496 MutexLocker ml(Heap_lock);
2497
2498 // Read the GC count while holding the Heap_lock
2499 gc_count_before = total_collections();
2500 old_marking_count_before = _old_marking_cycles_started;
2501 }
2502
2503 if (should_do_concurrent_full_gc(cause)) {
2504 // Schedule an initial-mark evacuation pause that will start a
2505 // concurrent cycle. We're setting word_size to 0 which means that
2506 // we are not requesting a post-GC allocation.
2507 VM_G1IncCollectionPause op(gc_count_before,
2508 0, /* word_size */
2509 true, /* should_initiate_conc_mark */
2510 g1_policy()->max_pause_time_ms(),
2511 cause);
2512
2513 VMThread::execute(&op);
2514 if (!op.pause_succeeded()) {
2515 if (old_marking_count_before == _old_marking_cycles_started) {
2516 retry_gc = op.should_retry_gc();
2517 } else {
2518 // A Full GC happened while we were trying to schedule the
2519 // initial-mark GC. No point in starting a new cycle given
2520 // that the whole heap was collected anyway.
2521 }
2522
2523 if (retry_gc) {
2524 if (GC_locker::is_active_and_needs_gc()) {
2525 GC_locker::stall_until_clear();
2526 }
2527 }
2528 }
2529 } else {
2530 if (cause == GCCause::_gc_locker
2531 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2532
2533 // Schedule a standard evacuation pause. We're setting word_size
2534 // to 0 which means that we are not requesting a post-GC allocation.
2535 VM_G1IncCollectionPause op(gc_count_before,
2536 0, /* word_size */
2537 false, /* should_initiate_conc_mark */
2538 g1_policy()->max_pause_time_ms(),
2539 cause);
2540 VMThread::execute(&op);
2541 } else {
2542 // Schedule a Full GC.
2543 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2544 VMThread::execute(&op);
2545 }
2546 }
2547 } while (retry_gc);
2548 }
2549
2550 bool G1CollectedHeap::is_in(const void* p) const {
2551 if (_g1_committed.contains(p)) {
2552 // Given that we know that p is in the committed space,
2553 // heap_region_containing_raw() should successfully
2554 // return the containing region.
2555 HeapRegion* hr = heap_region_containing_raw(p);
2556 return hr->is_in(p);
2557 } else {
2558 return _perm_gen->as_gen()->is_in(p);
2559 }
2560 }
2561
2562 // Iteration functions.
2563
2564 // Iterates an OopClosure over all ref-containing fields of objects
2565 // within a HeapRegion.
2566
2567 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2568 MemRegion _mr;
2569 OopClosure* _cl;
2570 public:
2571 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2572 : _mr(mr), _cl(cl) {}
2573 bool doHeapRegion(HeapRegion* r) {
2574 if (!r->continuesHumongous()) {
2575 r->oop_iterate(_cl);
2576 }
2577 return false;
2578 }
2579 };
2580
2581 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2582 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2583 heap_region_iterate(&blk);
2584 if (do_perm) {
2585 perm_gen()->oop_iterate(cl);
2586 }
2587 }
2588
2589 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2590 IterateOopClosureRegionClosure blk(mr, cl);
2591 heap_region_iterate(&blk);
2592 if (do_perm) {
2593 perm_gen()->oop_iterate(cl);
2594 }
2595 }
2596
2597 // Iterates an ObjectClosure over all objects within a HeapRegion.
2598
2599 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2600 ObjectClosure* _cl;
2601 public:
2602 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2603 bool doHeapRegion(HeapRegion* r) {
2604 if (! r->continuesHumongous()) {
2605 r->object_iterate(_cl);
2606 }
2607 return false;
2608 }
2609 };
2610
2611 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2612 IterateObjectClosureRegionClosure blk(cl);
2613 heap_region_iterate(&blk);
2614 if (do_perm) {
2615 perm_gen()->object_iterate(cl);
2616 }
2617 }
2618
2619 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2620 // FIXME: is this right?
2621 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2622 }
2623
2624 // Calls a SpaceClosure on a HeapRegion.
2625
2626 class SpaceClosureRegionClosure: public HeapRegionClosure {
2627 SpaceClosure* _cl;
2628 public:
2629 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2630 bool doHeapRegion(HeapRegion* r) {
2631 _cl->do_space(r);
2632 return false;
2633 }
2634 };
2635
2636 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2637 SpaceClosureRegionClosure blk(cl);
2638 heap_region_iterate(&blk);
2639 }
2640
2641 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2642 _hrs.iterate(cl);
2643 }
2644
2645 void
2646 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2647 uint worker_id,
2648 uint no_of_par_workers,
2649 jint claim_value) {
2650 const uint regions = n_regions();
2651 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2652 no_of_par_workers :
2653 1);
2654 assert(UseDynamicNumberOfGCThreads ||
2655 no_of_par_workers == workers()->total_workers(),
2656 "Non dynamic should use fixed number of workers");
2657 // try to spread out the starting points of the workers
2658 const HeapRegion* start_hr =
2659 start_region_for_worker(worker_id, no_of_par_workers);
2660 const uint start_index = start_hr->hrs_index();
2661
2662 // each worker will actually look at all regions
2663 for (uint count = 0; count < regions; ++count) {
2664 const uint index = (start_index + count) % regions;
2665 assert(0 <= index && index < regions, "sanity");
2666 HeapRegion* r = region_at(index);
2667 // we'll ignore "continues humongous" regions (we'll process them
2668 // when we come across their corresponding "start humongous"
2669 // region) and regions already claimed
2670 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2671 continue;
2672 }
2673 // OK, try to claim it
2674 if (r->claimHeapRegion(claim_value)) {
2675 // success!
2676 assert(!r->continuesHumongous(), "sanity");
2677 if (r->startsHumongous()) {
2678 // If the region is "starts humongous" we'll iterate over its
2679 // "continues humongous" first; in fact we'll do them
2680 // first. The order is important. In on case, calling the
2681 // closure on the "starts humongous" region might de-allocate
2682 // and clear all its "continues humongous" regions and, as a
2683 // result, we might end up processing them twice. So, we'll do
2684 // them first (notice: most closures will ignore them anyway) and
2685 // then we'll do the "starts humongous" region.
2686 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2687 HeapRegion* chr = region_at(ch_index);
2688
2689 // if the region has already been claimed or it's not
2690 // "continues humongous" we're done
2691 if (chr->claim_value() == claim_value ||
2692 !chr->continuesHumongous()) {
2693 break;
2694 }
2695
2696 // Noone should have claimed it directly. We can given
2697 // that we claimed its "starts humongous" region.
2698 assert(chr->claim_value() != claim_value, "sanity");
2699 assert(chr->humongous_start_region() == r, "sanity");
2700
2701 if (chr->claimHeapRegion(claim_value)) {
2702 // we should always be able to claim it; noone else should
2703 // be trying to claim this region
2704
2705 bool res2 = cl->doHeapRegion(chr);
2706 assert(!res2, "Should not abort");
2707
2708 // Right now, this holds (i.e., no closure that actually
2709 // does something with "continues humongous" regions
2710 // clears them). We might have to weaken it in the future,
2711 // but let's leave these two asserts here for extra safety.
2712 assert(chr->continuesHumongous(), "should still be the case");
2713 assert(chr->humongous_start_region() == r, "sanity");
2714 } else {
2715 guarantee(false, "we should not reach here");
2716 }
2717 }
2718 }
2719
2720 assert(!r->continuesHumongous(), "sanity");
2721 bool res = cl->doHeapRegion(r);
2722 assert(!res, "Should not abort");
2723 }
2724 }
2725 }
2726
2727 class ResetClaimValuesClosure: public HeapRegionClosure {
2728 public:
2729 bool doHeapRegion(HeapRegion* r) {
2730 r->set_claim_value(HeapRegion::InitialClaimValue);
2731 return false;
2732 }
2733 };
2734
2735 void G1CollectedHeap::reset_heap_region_claim_values() {
2736 ResetClaimValuesClosure blk;
2737 heap_region_iterate(&blk);
2738 }
2739
2740 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2741 ResetClaimValuesClosure blk;
2742 collection_set_iterate(&blk);
2743 }
2744
2745 #ifdef ASSERT
2746 // This checks whether all regions in the heap have the correct claim
2747 // value. I also piggy-backed on this a check to ensure that the
2748 // humongous_start_region() information on "continues humongous"
2749 // regions is correct.
2750
2751 class CheckClaimValuesClosure : public HeapRegionClosure {
2752 private:
2753 jint _claim_value;
2754 uint _failures;
2755 HeapRegion* _sh_region;
2756
2757 public:
2758 CheckClaimValuesClosure(jint claim_value) :
2759 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2760 bool doHeapRegion(HeapRegion* r) {
2761 if (r->claim_value() != _claim_value) {
2762 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2763 "claim value = %d, should be %d",
2764 HR_FORMAT_PARAMS(r),
2765 r->claim_value(), _claim_value);
2766 ++_failures;
2767 }
2768 if (!r->isHumongous()) {
2769 _sh_region = NULL;
2770 } else if (r->startsHumongous()) {
2771 _sh_region = r;
2772 } else if (r->continuesHumongous()) {
2773 if (r->humongous_start_region() != _sh_region) {
2774 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2775 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2776 HR_FORMAT_PARAMS(r),
2777 r->humongous_start_region(),
2778 _sh_region);
2779 ++_failures;
2780 }
2781 }
2782 return false;
2783 }
2784 uint failures() { return _failures; }
2785 };
2786
2787 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2788 CheckClaimValuesClosure cl(claim_value);
2789 heap_region_iterate(&cl);
2790 return cl.failures() == 0;
2791 }
2792
2793 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2794 private:
2795 jint _claim_value;
2796 uint _failures;
2797
2798 public:
2799 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2800 _claim_value(claim_value), _failures(0) { }
2801
2802 uint failures() { return _failures; }
2803
2804 bool doHeapRegion(HeapRegion* hr) {
2805 assert(hr->in_collection_set(), "how?");
2806 assert(!hr->isHumongous(), "H-region in CSet");
2807 if (hr->claim_value() != _claim_value) {
2808 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2809 "claim value = %d, should be %d",
2810 HR_FORMAT_PARAMS(hr),
2811 hr->claim_value(), _claim_value);
2812 _failures += 1;
2813 }
2814 return false;
2815 }
2816 };
2817
2818 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2819 CheckClaimValuesInCSetHRClosure cl(claim_value);
2820 collection_set_iterate(&cl);
2821 return cl.failures() == 0;
2822 }
2823 #endif // ASSERT
2824
2825 // Clear the cached CSet starting regions and (more importantly)
2826 // the time stamps. Called when we reset the GC time stamp.
2827 void G1CollectedHeap::clear_cset_start_regions() {
2828 assert(_worker_cset_start_region != NULL, "sanity");
2829 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2830
2831 int n_queues = MAX2((int)ParallelGCThreads, 1);
2832 for (int i = 0; i < n_queues; i++) {
2833 _worker_cset_start_region[i] = NULL;
2834 _worker_cset_start_region_time_stamp[i] = 0;
2835 }
2836 }
2837
2838 // Given the id of a worker, obtain or calculate a suitable
2839 // starting region for iterating over the current collection set.
2840 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2841 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2842
2843 HeapRegion* result = NULL;
2844 unsigned gc_time_stamp = get_gc_time_stamp();
2845
2846 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2847 // Cached starting region for current worker was set
2848 // during the current pause - so it's valid.
2849 // Note: the cached starting heap region may be NULL
2850 // (when the collection set is empty).
2851 result = _worker_cset_start_region[worker_i];
2852 assert(result == NULL || result->in_collection_set(), "sanity");
2853 return result;
2854 }
2855
2856 // The cached entry was not valid so let's calculate
2857 // a suitable starting heap region for this worker.
2858
2859 // We want the parallel threads to start their collection
2860 // set iteration at different collection set regions to
2861 // avoid contention.
2862 // If we have:
2863 // n collection set regions
2864 // p threads
2865 // Then thread t will start at region floor ((t * n) / p)
2866
2867 result = g1_policy()->collection_set();
2868 if (G1CollectedHeap::use_parallel_gc_threads()) {
2869 uint cs_size = g1_policy()->cset_region_length();
2870 uint active_workers = workers()->active_workers();
2871 assert(UseDynamicNumberOfGCThreads ||
2872 active_workers == workers()->total_workers(),
2873 "Unless dynamic should use total workers");
2874
2875 uint end_ind = (cs_size * worker_i) / active_workers;
2876 uint start_ind = 0;
2877
2878 if (worker_i > 0 &&
2879 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2880 // Previous workers starting region is valid
2881 // so let's iterate from there
2882 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2883 result = _worker_cset_start_region[worker_i - 1];
2884 }
2885
2886 for (uint i = start_ind; i < end_ind; i++) {
2887 result = result->next_in_collection_set();
2888 }
2889 }
2890
2891 // Note: the calculated starting heap region may be NULL
2892 // (when the collection set is empty).
2893 assert(result == NULL || result->in_collection_set(), "sanity");
2894 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2895 "should be updated only once per pause");
2896 _worker_cset_start_region[worker_i] = result;
2897 OrderAccess::storestore();
2898 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2899 return result;
2900 }
2901
2902 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2903 uint no_of_par_workers) {
2904 uint worker_num =
2905 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2906 assert(UseDynamicNumberOfGCThreads ||
2907 no_of_par_workers == workers()->total_workers(),
2908 "Non dynamic should use fixed number of workers");
2909 const uint start_index = n_regions() * worker_i / worker_num;
2910 return region_at(start_index);
2911 }
2912
2913 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2914 HeapRegion* r = g1_policy()->collection_set();
2915 while (r != NULL) {
2916 HeapRegion* next = r->next_in_collection_set();
2917 if (cl->doHeapRegion(r)) {
2918 cl->incomplete();
2919 return;
2920 }
2921 r = next;
2922 }
2923 }
2924
2925 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2926 HeapRegionClosure *cl) {
2927 if (r == NULL) {
2928 // The CSet is empty so there's nothing to do.
2929 return;
2930 }
2931
2932 assert(r->in_collection_set(),
2933 "Start region must be a member of the collection set.");
2934 HeapRegion* cur = r;
2935 while (cur != NULL) {
2936 HeapRegion* next = cur->next_in_collection_set();
2937 if (cl->doHeapRegion(cur) && false) {
2938 cl->incomplete();
2939 return;
2940 }
2941 cur = next;
2942 }
2943 cur = g1_policy()->collection_set();
2944 while (cur != r) {
2945 HeapRegion* next = cur->next_in_collection_set();
2946 if (cl->doHeapRegion(cur) && false) {
2947 cl->incomplete();
2948 return;
2949 }
2950 cur = next;
2951 }
2952 }
2953
2954 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2955 return n_regions() > 0 ? region_at(0) : NULL;
2956 }
2957
2958
2959 Space* G1CollectedHeap::space_containing(const void* addr) const {
2960 Space* res = heap_region_containing(addr);
2961 if (res == NULL)
2962 res = perm_gen()->space_containing(addr);
2963 return res;
2964 }
2965
2966 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2967 Space* sp = space_containing(addr);
2968 if (sp != NULL) {
2969 return sp->block_start(addr);
2970 }
2971 return NULL;
2972 }
2973
2974 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2975 Space* sp = space_containing(addr);
2976 assert(sp != NULL, "block_size of address outside of heap");
2977 return sp->block_size(addr);
2978 }
2979
2980 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2981 Space* sp = space_containing(addr);
2982 return sp->block_is_obj(addr);
2983 }
2984
2985 bool G1CollectedHeap::supports_tlab_allocation() const {
2986 return true;
2987 }
2988
2989 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2990 return HeapRegion::GrainBytes;
2991 }
2992
2993 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2994 // Return the remaining space in the cur alloc region, but not less than
2995 // the min TLAB size.
2996
2997 // Also, this value can be at most the humongous object threshold,
2998 // since we can't allow tlabs to grow big enough to accomodate
2999 // humongous objects.
3000
3001 HeapRegion* hr = _mutator_alloc_region.get();
3002 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3003 if (hr == NULL) {
3004 return max_tlab_size;
3005 } else {
3006 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3007 }
3008 }
3009
3010 size_t G1CollectedHeap::max_capacity() const {
3011 return _g1_reserved.byte_size();
3012 }
3013
3014 jlong G1CollectedHeap::millis_since_last_gc() {
3015 // assert(false, "NYI");
3016 return 0;
3017 }
3018
3019 void G1CollectedHeap::prepare_for_verify() {
3020 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3021 ensure_parsability(false);
3022 }
3023 g1_rem_set()->prepare_for_verify();
3024 }
3025
3026 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3027 VerifyOption vo) {
3028 switch (vo) {
3029 case VerifyOption_G1UsePrevMarking:
3030 return hr->obj_allocated_since_prev_marking(obj);
3031 case VerifyOption_G1UseNextMarking:
3032 return hr->obj_allocated_since_next_marking(obj);
3033 case VerifyOption_G1UseMarkWord:
3034 return false;
3035 default:
3036 ShouldNotReachHere();
3037 }
3038 return false; // keep some compilers happy
3039 }
3040
3041 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3042 switch (vo) {
3043 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3044 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3045 case VerifyOption_G1UseMarkWord: return NULL;
3046 default: ShouldNotReachHere();
3047 }
3048 return NULL; // keep some compilers happy
3049 }
3050
3051 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3052 switch (vo) {
3053 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3054 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3055 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3056 default: ShouldNotReachHere();
3057 }
3058 return false; // keep some compilers happy
3059 }
3060
3061 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3062 switch (vo) {
3063 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3064 case VerifyOption_G1UseNextMarking: return "NTAMS";
3065 case VerifyOption_G1UseMarkWord: return "NONE";
3066 default: ShouldNotReachHere();
3067 }
3068 return NULL; // keep some compilers happy
3069 }
3070
3071 class VerifyLivenessOopClosure: public OopClosure {
3072 G1CollectedHeap* _g1h;
3073 VerifyOption _vo;
3074 public:
3075 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3076 _g1h(g1h), _vo(vo)
3077 { }
3078 void do_oop(narrowOop *p) { do_oop_work(p); }
3079 void do_oop( oop *p) { do_oop_work(p); }
3080
3081 template <class T> void do_oop_work(T *p) {
3082 oop obj = oopDesc::load_decode_heap_oop(p);
3083 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3084 "Dead object referenced by a not dead object");
3085 }
3086 };
3087
3088 class VerifyObjsInRegionClosure: public ObjectClosure {
3089 private:
3090 G1CollectedHeap* _g1h;
3091 size_t _live_bytes;
3092 HeapRegion *_hr;
3093 VerifyOption _vo;
3094 public:
3095 // _vo == UsePrevMarking -> use "prev" marking information,
3096 // _vo == UseNextMarking -> use "next" marking information,
3097 // _vo == UseMarkWord -> use mark word from object header.
3098 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3099 : _live_bytes(0), _hr(hr), _vo(vo) {
3100 _g1h = G1CollectedHeap::heap();
3101 }
3102 void do_object(oop o) {
3103 VerifyLivenessOopClosure isLive(_g1h, _vo);
3104 assert(o != NULL, "Huh?");
3105 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3106 // If the object is alive according to the mark word,
3107 // then verify that the marking information agrees.
3108 // Note we can't verify the contra-positive of the
3109 // above: if the object is dead (according to the mark
3110 // word), it may not be marked, or may have been marked
3111 // but has since became dead, or may have been allocated
3112 // since the last marking.
3113 if (_vo == VerifyOption_G1UseMarkWord) {
3114 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3115 }
3116
3117 o->oop_iterate(&isLive);
3118 if (!_hr->obj_allocated_since_prev_marking(o)) {
3119 size_t obj_size = o->size(); // Make sure we don't overflow
3120 _live_bytes += (obj_size * HeapWordSize);
3121 }
3122 }
3123 }
3124 size_t live_bytes() { return _live_bytes; }
3125 };
3126
3127 class PrintObjsInRegionClosure : public ObjectClosure {
3128 HeapRegion *_hr;
3129 G1CollectedHeap *_g1;
3130 public:
3131 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3132 _g1 = G1CollectedHeap::heap();
3133 };
3134
3135 void do_object(oop o) {
3136 if (o != NULL) {
3137 HeapWord *start = (HeapWord *) o;
3138 size_t word_sz = o->size();
3139 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3140 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3141 (void*) o, word_sz,
3142 _g1->isMarkedPrev(o),
3143 _g1->isMarkedNext(o),
3144 _hr->obj_allocated_since_prev_marking(o));
3145 HeapWord *end = start + word_sz;
3146 HeapWord *cur;
3147 int *val;
3148 for (cur = start; cur < end; cur++) {
3149 val = (int *) cur;
3150 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3151 }
3152 }
3153 }
3154 };
3155
3156 class VerifyRegionClosure: public HeapRegionClosure {
3157 private:
3158 bool _par;
3159 VerifyOption _vo;
3160 bool _failures;
3161 public:
3162 // _vo == UsePrevMarking -> use "prev" marking information,
3163 // _vo == UseNextMarking -> use "next" marking information,
3164 // _vo == UseMarkWord -> use mark word from object header.
3165 VerifyRegionClosure(bool par, VerifyOption vo)
3166 : _par(par),
3167 _vo(vo),
3168 _failures(false) {}
3169
3170 bool failures() {
3171 return _failures;
3172 }
3173
3174 bool doHeapRegion(HeapRegion* r) {
3175 if (!r->continuesHumongous()) {
3176 bool failures = false;
3177 r->verify(_vo, &failures);
3178 if (failures) {
3179 _failures = true;
3180 } else {
3181 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3182 r->object_iterate(¬_dead_yet_cl);
3183 if (_vo != VerifyOption_G1UseNextMarking) {
3184 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3185 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3186 "max_live_bytes "SIZE_FORMAT" "
3187 "< calculated "SIZE_FORMAT,
3188 r->bottom(), r->end(),
3189 r->max_live_bytes(),
3190 not_dead_yet_cl.live_bytes());
3191 _failures = true;
3192 }
3193 } else {
3194 // When vo == UseNextMarking we cannot currently do a sanity
3195 // check on the live bytes as the calculation has not been
3196 // finalized yet.
3197 }
3198 }
3199 }
3200 return false; // stop the region iteration if we hit a failure
3201 }
3202 };
3203
3204 class VerifyRootsClosure: public OopsInGenClosure {
3205 private:
3206 G1CollectedHeap* _g1h;
3207 VerifyOption _vo;
3208 bool _failures;
3209 public:
3210 // _vo == UsePrevMarking -> use "prev" marking information,
3211 // _vo == UseNextMarking -> use "next" marking information,
3212 // _vo == UseMarkWord -> use mark word from object header.
3213 VerifyRootsClosure(VerifyOption vo) :
3214 _g1h(G1CollectedHeap::heap()),
3215 _vo(vo),
3216 _failures(false) { }
3217
3218 bool failures() { return _failures; }
3219
3220 template <class T> void do_oop_nv(T* p) {
3221 T heap_oop = oopDesc::load_heap_oop(p);
3222 if (!oopDesc::is_null(heap_oop)) {
3223 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3224 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3225 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3226 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3227 if (_vo == VerifyOption_G1UseMarkWord) {
3228 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3229 }
3230 obj->print_on(gclog_or_tty);
3231 _failures = true;
3232 }
3233 }
3234 }
3235
3236 void do_oop(oop* p) { do_oop_nv(p); }
3237 void do_oop(narrowOop* p) { do_oop_nv(p); }
3238 };
3239
3240 // This is the task used for parallel heap verification.
3241
3242 class G1ParVerifyTask: public AbstractGangTask {
3243 private:
3244 G1CollectedHeap* _g1h;
3245 VerifyOption _vo;
3246 bool _failures;
3247
3248 public:
3249 // _vo == UsePrevMarking -> use "prev" marking information,
3250 // _vo == UseNextMarking -> use "next" marking information,
3251 // _vo == UseMarkWord -> use mark word from object header.
3252 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3253 AbstractGangTask("Parallel verify task"),
3254 _g1h(g1h),
3255 _vo(vo),
3256 _failures(false) { }
3257
3258 bool failures() {
3259 return _failures;
3260 }
3261
3262 void work(uint worker_id) {
3263 HandleMark hm;
3264 VerifyRegionClosure blk(true, _vo);
3265 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3266 _g1h->workers()->active_workers(),
3267 HeapRegion::ParVerifyClaimValue);
3268 if (blk.failures()) {
3269 _failures = true;
3270 }
3271 }
3272 };
3273
3274 void G1CollectedHeap::verify(bool silent) {
3275 verify(silent, VerifyOption_G1UsePrevMarking);
3276 }
3277
3278 void G1CollectedHeap::verify(bool silent,
3279 VerifyOption vo) {
3280 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3281 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3282 VerifyRootsClosure rootsCl(vo);
3283
3284 assert(Thread::current()->is_VM_thread(),
3285 "Expected to be executed serially by the VM thread at this point");
3286
3287 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3288
3289 // We apply the relevant closures to all the oops in the
3290 // system dictionary, the string table and the code cache.
3291 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3292
3293 process_strong_roots(true, // activate StrongRootsScope
3294 true, // we set "collecting perm gen" to true,
3295 // so we don't reset the dirty cards in the perm gen.
3296 ScanningOption(so), // roots scanning options
3297 &rootsCl,
3298 &blobsCl,
3299 &rootsCl);
3300
3301 // If we're verifying after the marking phase of a Full GC then we can't
3302 // treat the perm gen as roots into the G1 heap. Some of the objects in
3303 // the perm gen may be dead and hence not marked. If one of these dead
3304 // objects is considered to be a root then we may end up with a false
3305 // "Root location <x> points to dead ob <y>" failure.
3306 if (vo != VerifyOption_G1UseMarkWord) {
3307 // Since we used "collecting_perm_gen" == true above, we will not have
3308 // checked the refs from perm into the G1-collected heap. We check those
3309 // references explicitly below. Whether the relevant cards are dirty
3310 // is checked further below in the rem set verification.
3311 if (!silent) { gclog_or_tty->print("Permgen roots "); }
3312 perm_gen()->oop_iterate(&rootsCl);
3313 }
3314 bool failures = rootsCl.failures();
3315
3316 if (vo != VerifyOption_G1UseMarkWord) {
3317 // If we're verifying during a full GC then the region sets
3318 // will have been torn down at the start of the GC. Therefore
3319 // verifying the region sets will fail. So we only verify
3320 // the region sets when not in a full GC.
3321 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3322 verify_region_sets();
3323 }
3324
3325 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3326 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3327 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3328 "sanity check");
3329
3330 G1ParVerifyTask task(this, vo);
3331 assert(UseDynamicNumberOfGCThreads ||
3332 workers()->active_workers() == workers()->total_workers(),
3333 "If not dynamic should be using all the workers");
3334 int n_workers = workers()->active_workers();
3335 set_par_threads(n_workers);
3336 workers()->run_task(&task);
3337 set_par_threads(0);
3338 if (task.failures()) {
3339 failures = true;
3340 }
3341
3342 // Checks that the expected amount of parallel work was done.
3343 // The implication is that n_workers is > 0.
3344 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3345 "sanity check");
3346
3347 reset_heap_region_claim_values();
3348
3349 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3350 "sanity check");
3351 } else {
3352 VerifyRegionClosure blk(false, vo);
3353 heap_region_iterate(&blk);
3354 if (blk.failures()) {
3355 failures = true;
3356 }
3357 }
3358 if (!silent) gclog_or_tty->print("RemSet ");
3359 rem_set()->verify();
3360
3361 if (failures) {
3362 gclog_or_tty->print_cr("Heap:");
3363 // It helps to have the per-region information in the output to
3364 // help us track down what went wrong. This is why we call
3365 // print_extended_on() instead of print_on().
3366 print_extended_on(gclog_or_tty);
3367 gclog_or_tty->print_cr("");
3368 #ifndef PRODUCT
3369 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3370 concurrent_mark()->print_reachable("at-verification-failure",
3371 vo, false /* all */);
3372 }
3373 #endif
3374 gclog_or_tty->flush();
3375 }
3376 guarantee(!failures, "there should not have been any failures");
3377 } else {
3378 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3379 }
3380 }
3381
3382 class PrintRegionClosure: public HeapRegionClosure {
3383 outputStream* _st;
3384 public:
3385 PrintRegionClosure(outputStream* st) : _st(st) {}
3386 bool doHeapRegion(HeapRegion* r) {
3387 r->print_on(_st);
3388 return false;
3389 }
3390 };
3391
3392 void G1CollectedHeap::print_on(outputStream* st) const {
3393 st->print(" %-20s", "garbage-first heap");
3394 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3395 capacity()/K, used_unlocked()/K);
3396 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3397 _g1_storage.low_boundary(),
3398 _g1_storage.high(),
3399 _g1_storage.high_boundary());
3400 st->cr();
3401 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3402 uint young_regions = _young_list->length();
3403 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3404 (size_t) young_regions * HeapRegion::GrainBytes / K);
3405 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3406 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3407 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3408 st->cr();
3409 perm()->as_gen()->print_on(st);
3410 }
3411
3412 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3413 print_on(st);
3414
3415 // Print the per-region information.
3416 st->cr();
3417 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3418 "HS=humongous(starts), HC=humongous(continues), "
3419 "CS=collection set, F=free, TS=gc time stamp, "
3420 "PTAMS=previous top-at-mark-start, "
3421 "NTAMS=next top-at-mark-start)");
3422 PrintRegionClosure blk(st);
3423 heap_region_iterate(&blk);
3424 }
3425
3426 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3427 if (G1CollectedHeap::use_parallel_gc_threads()) {
3428 workers()->print_worker_threads_on(st);
3429 }
3430 _cmThread->print_on(st);
3431 st->cr();
3432 _cm->print_worker_threads_on(st);
3433 _cg1r->print_worker_threads_on(st);
3434 st->cr();
3435 }
3436
3437 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3438 if (G1CollectedHeap::use_parallel_gc_threads()) {
3439 workers()->threads_do(tc);
3440 }
3441 tc->do_thread(_cmThread);
3442 _cg1r->threads_do(tc);
3443 }
3444
3445 void G1CollectedHeap::print_tracing_info() const {
3446 // We'll overload this to mean "trace GC pause statistics."
3447 if (TraceGen0Time || TraceGen1Time) {
3448 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3449 // to that.
3450 g1_policy()->print_tracing_info();
3451 }
3452 if (G1SummarizeRSetStats) {
3453 g1_rem_set()->print_summary_info();
3454 }
3455 if (G1SummarizeConcMark) {
3456 concurrent_mark()->print_summary_info();
3457 }
3458 g1_policy()->print_yg_surv_rate_info();
3459 SpecializationStats::print();
3460 }
3461
3462 #ifndef PRODUCT
3463 // Helpful for debugging RSet issues.
3464
3465 class PrintRSetsClosure : public HeapRegionClosure {
3466 private:
3467 const char* _msg;
3468 size_t _occupied_sum;
3469
3470 public:
3471 bool doHeapRegion(HeapRegion* r) {
3472 HeapRegionRemSet* hrrs = r->rem_set();
3473 size_t occupied = hrrs->occupied();
3474 _occupied_sum += occupied;
3475
3476 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3477 HR_FORMAT_PARAMS(r));
3478 if (occupied == 0) {
3479 gclog_or_tty->print_cr(" RSet is empty");
3480 } else {
3481 hrrs->print();
3482 }
3483 gclog_or_tty->print_cr("----------");
3484 return false;
3485 }
3486
3487 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3488 gclog_or_tty->cr();
3489 gclog_or_tty->print_cr("========================================");
3490 gclog_or_tty->print_cr(msg);
3491 gclog_or_tty->cr();
3492 }
3493
3494 ~PrintRSetsClosure() {
3495 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3496 gclog_or_tty->print_cr("========================================");
3497 gclog_or_tty->cr();
3498 }
3499 };
3500
3501 void G1CollectedHeap::print_cset_rsets() {
3502 PrintRSetsClosure cl("Printing CSet RSets");
3503 collection_set_iterate(&cl);
3504 }
3505
3506 void G1CollectedHeap::print_all_rsets() {
3507 PrintRSetsClosure cl("Printing All RSets");;
3508 heap_region_iterate(&cl);
3509 }
3510 #endif // PRODUCT
3511
3512 G1CollectedHeap* G1CollectedHeap::heap() {
3513 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3514 "not a garbage-first heap");
3515 return _g1h;
3516 }
3517
3518 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3519 // always_do_update_barrier = false;
3520 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3521 // Call allocation profiler
3522 AllocationProfiler::iterate_since_last_gc();
3523 // Fill TLAB's and such
3524 ensure_parsability(true);
3525 }
3526
3527 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3528 // FIXME: what is this about?
3529 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3530 // is set.
3531 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3532 "derived pointer present"));
3533 // always_do_update_barrier = true;
3534
3535 // We have just completed a GC. Update the soft reference
3536 // policy with the new heap occupancy
3537 Universe::update_heap_info_at_gc();
3538 }
3539
3540 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3541 unsigned int gc_count_before,
3542 bool* succeeded) {
3543 assert_heap_not_locked_and_not_at_safepoint();
3544 g1_policy()->record_stop_world_start();
3545 VM_G1IncCollectionPause op(gc_count_before,
3546 word_size,
3547 false, /* should_initiate_conc_mark */
3548 g1_policy()->max_pause_time_ms(),
3549 GCCause::_g1_inc_collection_pause);
3550 VMThread::execute(&op);
3551
3552 HeapWord* result = op.result();
3553 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3554 assert(result == NULL || ret_succeeded,
3555 "the result should be NULL if the VM did not succeed");
3556 *succeeded = ret_succeeded;
3557
3558 assert_heap_not_locked();
3559 return result;
3560 }
3561
3562 void
3563 G1CollectedHeap::doConcurrentMark() {
3564 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3565 if (!_cmThread->in_progress()) {
3566 _cmThread->set_started();
3567 CGC_lock->notify();
3568 }
3569 }
3570
3571 size_t G1CollectedHeap::pending_card_num() {
3572 size_t extra_cards = 0;
3573 JavaThread *curr = Threads::first();
3574 while (curr != NULL) {
3575 DirtyCardQueue& dcq = curr->dirty_card_queue();
3576 extra_cards += dcq.size();
3577 curr = curr->next();
3578 }
3579 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3580 size_t buffer_size = dcqs.buffer_size();
3581 size_t buffer_num = dcqs.completed_buffers_num();
3582 return buffer_size * buffer_num + extra_cards;
3583 }
3584
3585 size_t G1CollectedHeap::max_pending_card_num() {
3586 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3587 size_t buffer_size = dcqs.buffer_size();
3588 size_t buffer_num = dcqs.completed_buffers_num();
3589 int thread_num = Threads::number_of_threads();
3590 return (buffer_num + thread_num) * buffer_size;
3591 }
3592
3593 size_t G1CollectedHeap::cards_scanned() {
3594 return g1_rem_set()->cardsScanned();
3595 }
3596
3597 void
3598 G1CollectedHeap::setup_surviving_young_words() {
3599 assert(_surviving_young_words == NULL, "pre-condition");
3600 uint array_length = g1_policy()->young_cset_region_length();
3601 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length);
3602 if (_surviving_young_words == NULL) {
3603 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3604 "Not enough space for young surv words summary.");
3605 }
3606 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3607 #ifdef ASSERT
3608 for (uint i = 0; i < array_length; ++i) {
3609 assert( _surviving_young_words[i] == 0, "memset above" );
3610 }
3611 #endif // !ASSERT
3612 }
3613
3614 void
3615 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3616 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3617 uint array_length = g1_policy()->young_cset_region_length();
3618 for (uint i = 0; i < array_length; ++i) {
3619 _surviving_young_words[i] += surv_young_words[i];
3620 }
3621 }
3622
3623 void
3624 G1CollectedHeap::cleanup_surviving_young_words() {
3625 guarantee( _surviving_young_words != NULL, "pre-condition" );
3626 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3627 _surviving_young_words = NULL;
3628 }
3629
3630 #ifdef ASSERT
3631 class VerifyCSetClosure: public HeapRegionClosure {
3632 public:
3633 bool doHeapRegion(HeapRegion* hr) {
3634 // Here we check that the CSet region's RSet is ready for parallel
3635 // iteration. The fields that we'll verify are only manipulated
3636 // when the region is part of a CSet and is collected. Afterwards,
3637 // we reset these fields when we clear the region's RSet (when the
3638 // region is freed) so they are ready when the region is
3639 // re-allocated. The only exception to this is if there's an
3640 // evacuation failure and instead of freeing the region we leave
3641 // it in the heap. In that case, we reset these fields during
3642 // evacuation failure handling.
3643 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3644
3645 // Here's a good place to add any other checks we'd like to
3646 // perform on CSet regions.
3647 return false;
3648 }
3649 };
3650 #endif // ASSERT
3651
3652 #if TASKQUEUE_STATS
3653 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3654 st->print_raw_cr("GC Task Stats");
3655 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3656 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3657 }
3658
3659 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3660 print_taskqueue_stats_hdr(st);
3661
3662 TaskQueueStats totals;
3663 const int n = workers() != NULL ? workers()->total_workers() : 1;
3664 for (int i = 0; i < n; ++i) {
3665 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3666 totals += task_queue(i)->stats;
3667 }
3668 st->print_raw("tot "); totals.print(st); st->cr();
3669
3670 DEBUG_ONLY(totals.verify());
3671 }
3672
3673 void G1CollectedHeap::reset_taskqueue_stats() {
3674 const int n = workers() != NULL ? workers()->total_workers() : 1;
3675 for (int i = 0; i < n; ++i) {
3676 task_queue(i)->stats.reset();
3677 }
3678 }
3679 #endif // TASKQUEUE_STATS
3680
3681 bool
3682 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3683 assert_at_safepoint(true /* should_be_vm_thread */);
3684 guarantee(!is_gc_active(), "collection is not reentrant");
3685
3686 if (GC_locker::check_active_before_gc()) {
3687 return false;
3688 }
3689
3690 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3691 ResourceMark rm;
3692
3693 print_heap_before_gc();
3694
3695 HRSPhaseSetter x(HRSPhaseEvacuation);
3696 verify_region_sets_optional();
3697 verify_dirty_young_regions();
3698
3699 // This call will decide whether this pause is an initial-mark
3700 // pause. If it is, during_initial_mark_pause() will return true
3701 // for the duration of this pause.
3702 g1_policy()->decide_on_conc_mark_initiation();
3703
3704 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3705 assert(!g1_policy()->during_initial_mark_pause() ||
3706 g1_policy()->gcs_are_young(), "sanity");
3707
3708 // We also do not allow mixed GCs during marking.
3709 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3710
3711 // Record whether this pause is an initial mark. When the current
3712 // thread has completed its logging output and it's safe to signal
3713 // the CM thread, the flag's value in the policy has been reset.
3714 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3715
3716 // Inner scope for scope based logging, timers, and stats collection
3717 {
3718 if (g1_policy()->during_initial_mark_pause()) {
3719 // We are about to start a marking cycle, so we increment the
3720 // full collection counter.
3721 increment_old_marking_cycles_started();
3722 }
3723 // if the log level is "finer" is on, we'll print long statistics information
3724 // in the collector policy code, so let's not print this as the output
3725 // is messy if we do.
3726 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
3727 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3728
3729 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3730 .append(g1_policy()->gcs_are_young() ? " (young)" : " (mixed)")
3731 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3732 TraceTime t(gc_cause_str, G1Log::fine() && !G1Log::finer(), true, gclog_or_tty);
3733
3734 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3735 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3736
3737 // If the secondary_free_list is not empty, append it to the
3738 // free_list. No need to wait for the cleanup operation to finish;
3739 // the region allocation code will check the secondary_free_list
3740 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3741 // set, skip this step so that the region allocation code has to
3742 // get entries from the secondary_free_list.
3743 if (!G1StressConcRegionFreeing) {
3744 append_secondary_free_list_if_not_empty_with_lock();
3745 }
3746
3747 assert(check_young_list_well_formed(),
3748 "young list should be well formed");
3749
3750 // Don't dynamically change the number of GC threads this early. A value of
3751 // 0 is used to indicate serial work. When parallel work is done,
3752 // it will be set.
3753
3754 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3755 IsGCActiveMark x;
3756
3757 gc_prologue(false);
3758 increment_total_collections(false /* full gc */);
3759 increment_gc_time_stamp();
3760
3761 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3762 HandleMark hm; // Discard invalid handles created during verification
3763 gclog_or_tty->print(" VerifyBeforeGC:");
3764 prepare_for_verify();
3765 Universe::verify(/* silent */ false,
3766 /* option */ VerifyOption_G1UsePrevMarking);
3767 }
3768
3769 COMPILER2_PRESENT(DerivedPointerTable::clear());
3770
3771 // Please see comment in g1CollectedHeap.hpp and
3772 // G1CollectedHeap::ref_processing_init() to see how
3773 // reference processing currently works in G1.
3774
3775 // Enable discovery in the STW reference processor
3776 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3777 true /*verify_no_refs*/);
3778
3779 {
3780 // We want to temporarily turn off discovery by the
3781 // CM ref processor, if necessary, and turn it back on
3782 // on again later if we do. Using a scoped
3783 // NoRefDiscovery object will do this.
3784 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3785
3786 // Forget the current alloc region (we might even choose it to be part
3787 // of the collection set!).
3788 release_mutator_alloc_region();
3789
3790 // We should call this after we retire the mutator alloc
3791 // region(s) so that all the ALLOC / RETIRE events are generated
3792 // before the start GC event.
3793 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3794
3795 // The elapsed time induced by the start time below deliberately elides
3796 // the possible verification above.
3797 double start_time_sec = os::elapsedTime();
3798 size_t start_used_bytes = used();
3799
3800 #if YOUNG_LIST_VERBOSE
3801 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3802 _young_list->print();
3803 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3804 #endif // YOUNG_LIST_VERBOSE
3805
3806 g1_policy()->record_collection_pause_start(start_time_sec,
3807 start_used_bytes);
3808
3809 double scan_wait_start = os::elapsedTime();
3810 // We have to wait until the CM threads finish scanning the
3811 // root regions as it's the only way to ensure that all the
3812 // objects on them have been correctly scanned before we start
3813 // moving them during the GC.
3814 bool waited = _cm->root_regions()->wait_until_scan_finished();
3815 if (waited) {
3816 double scan_wait_end = os::elapsedTime();
3817 double wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3818 g1_policy()->record_root_region_scan_wait_time(wait_time_ms);
3819 }
3820
3821 #if YOUNG_LIST_VERBOSE
3822 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3823 _young_list->print();
3824 #endif // YOUNG_LIST_VERBOSE
3825
3826 if (g1_policy()->during_initial_mark_pause()) {
3827 concurrent_mark()->checkpointRootsInitialPre();
3828 }
3829 perm_gen()->save_marks();
3830
3831 #if YOUNG_LIST_VERBOSE
3832 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3833 _young_list->print();
3834 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3835 #endif // YOUNG_LIST_VERBOSE
3836
3837 g1_policy()->finalize_cset(target_pause_time_ms);
3838
3839 _cm->note_start_of_gc();
3840 // We should not verify the per-thread SATB buffers given that
3841 // we have not filtered them yet (we'll do so during the
3842 // GC). We also call this after finalize_cset() to
3843 // ensure that the CSet has been finalized.
3844 _cm->verify_no_cset_oops(true /* verify_stacks */,
3845 true /* verify_enqueued_buffers */,
3846 false /* verify_thread_buffers */,
3847 true /* verify_fingers */);
3848
3849 if (_hr_printer.is_active()) {
3850 HeapRegion* hr = g1_policy()->collection_set();
3851 while (hr != NULL) {
3852 G1HRPrinter::RegionType type;
3853 if (!hr->is_young()) {
3854 type = G1HRPrinter::Old;
3855 } else if (hr->is_survivor()) {
3856 type = G1HRPrinter::Survivor;
3857 } else {
3858 type = G1HRPrinter::Eden;
3859 }
3860 _hr_printer.cset(hr);
3861 hr = hr->next_in_collection_set();
3862 }
3863 }
3864
3865 #ifdef ASSERT
3866 VerifyCSetClosure cl;
3867 collection_set_iterate(&cl);
3868 #endif // ASSERT
3869
3870 setup_surviving_young_words();
3871
3872 // Initialize the GC alloc regions.
3873 init_gc_alloc_regions();
3874
3875 // Actually do the work...
3876 evacuate_collection_set();
3877
3878 // We do this to mainly verify the per-thread SATB buffers
3879 // (which have been filtered by now) since we didn't verify
3880 // them earlier. No point in re-checking the stacks / enqueued
3881 // buffers given that the CSet has not changed since last time
3882 // we checked.
3883 _cm->verify_no_cset_oops(false /* verify_stacks */,
3884 false /* verify_enqueued_buffers */,
3885 true /* verify_thread_buffers */,
3886 true /* verify_fingers */);
3887
3888 free_collection_set(g1_policy()->collection_set());
3889 g1_policy()->clear_collection_set();
3890
3891 cleanup_surviving_young_words();
3892
3893 // Start a new incremental collection set for the next pause.
3894 g1_policy()->start_incremental_cset_building();
3895
3896 // Clear the _cset_fast_test bitmap in anticipation of adding
3897 // regions to the incremental collection set for the next
3898 // evacuation pause.
3899 clear_cset_fast_test();
3900
3901 _young_list->reset_sampled_info();
3902
3903 // Don't check the whole heap at this point as the
3904 // GC alloc regions from this pause have been tagged
3905 // as survivors and moved on to the survivor list.
3906 // Survivor regions will fail the !is_young() check.
3907 assert(check_young_list_empty(false /* check_heap */),
3908 "young list should be empty");
3909
3910 #if YOUNG_LIST_VERBOSE
3911 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3912 _young_list->print();
3913 #endif // YOUNG_LIST_VERBOSE
3914
3915 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3916 _young_list->first_survivor_region(),
3917 _young_list->last_survivor_region());
3918
3919 _young_list->reset_auxilary_lists();
3920
3921 if (evacuation_failed()) {
3922 _summary_bytes_used = recalculate_used();
3923 } else {
3924 // The "used" of the the collection set have already been subtracted
3925 // when they were freed. Add in the bytes evacuated.
3926 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3927 }
3928
3929 if (g1_policy()->during_initial_mark_pause()) {
3930 // We have to do this before we notify the CM threads that
3931 // they can start working to make sure that all the
3932 // appropriate initialization is done on the CM object.
3933 concurrent_mark()->checkpointRootsInitialPost();
3934 set_marking_started();
3935 // Note that we don't actually trigger the CM thread at
3936 // this point. We do that later when we're sure that
3937 // the current thread has completed its logging output.
3938 }
3939
3940 allocate_dummy_regions();
3941
3942 #if YOUNG_LIST_VERBOSE
3943 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3944 _young_list->print();
3945 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3946 #endif // YOUNG_LIST_VERBOSE
3947
3948 init_mutator_alloc_region();
3949
3950 {
3951 size_t expand_bytes = g1_policy()->expansion_amount();
3952 if (expand_bytes > 0) {
3953 size_t bytes_before = capacity();
3954 // No need for an ergo verbose message here,
3955 // expansion_amount() does this when it returns a value > 0.
3956 if (!expand(expand_bytes)) {
3957 // We failed to expand the heap so let's verify that
3958 // committed/uncommitted amount match the backing store
3959 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3960 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3961 }
3962 }
3963 }
3964
3965 // We redo the verificaiton but now wrt to the new CSet which
3966 // has just got initialized after the previous CSet was freed.
3967 _cm->verify_no_cset_oops(true /* verify_stacks */,
3968 true /* verify_enqueued_buffers */,
3969 true /* verify_thread_buffers */,
3970 true /* verify_fingers */);
3971 _cm->note_end_of_gc();
3972
3973 double end_time_sec = os::elapsedTime();
3974 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3975 g1_policy()->record_pause_time_ms(pause_time_ms);
3976 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3977 workers()->active_workers() : 1);
3978 g1_policy()->record_collection_pause_end(active_workers);
3979
3980 MemoryService::track_memory_usage();
3981
3982 // In prepare_for_verify() below we'll need to scan the deferred
3983 // update buffers to bring the RSets up-to-date if
3984 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3985 // the update buffers we'll probably need to scan cards on the
3986 // regions we just allocated to (i.e., the GC alloc
3987 // regions). However, during the last GC we called
3988 // set_saved_mark() on all the GC alloc regions, so card
3989 // scanning might skip the [saved_mark_word()...top()] area of
3990 // those regions (i.e., the area we allocated objects into
3991 // during the last GC). But it shouldn't. Given that
3992 // saved_mark_word() is conditional on whether the GC time stamp
3993 // on the region is current or not, by incrementing the GC time
3994 // stamp here we invalidate all the GC time stamps on all the
3995 // regions and saved_mark_word() will simply return top() for
3996 // all the regions. This is a nicer way of ensuring this rather
3997 // than iterating over the regions and fixing them. In fact, the
3998 // GC time stamp increment here also ensures that
3999 // saved_mark_word() will return top() between pauses, i.e.,
4000 // during concurrent refinement. So we don't need the
4001 // is_gc_active() check to decided which top to use when
4002 // scanning cards (see CR 7039627).
4003 increment_gc_time_stamp();
4004
4005 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
4006 HandleMark hm; // Discard invalid handles created during verification
4007 gclog_or_tty->print(" VerifyAfterGC:");
4008 prepare_for_verify();
4009 Universe::verify(/* silent */ false,
4010 /* option */ VerifyOption_G1UsePrevMarking);
4011 }
4012
4013 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4014 ref_processor_stw()->verify_no_references_recorded();
4015
4016 // CM reference discovery will be re-enabled if necessary.
4017 }
4018
4019 // We should do this after we potentially expand the heap so
4020 // that all the COMMIT events are generated before the end GC
4021 // event, and after we retire the GC alloc regions so that all
4022 // RETIRE events are generated before the end GC event.
4023 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4024
4025 // We have to do this after we decide whether to expand the heap or not.
4026 g1_policy()->print_heap_transition();
4027
4028 if (mark_in_progress()) {
4029 concurrent_mark()->update_g1_committed();
4030 }
4031
4032 #ifdef TRACESPINNING
4033 ParallelTaskTerminator::print_termination_counts();
4034 #endif
4035
4036 gc_epilogue(false);
4037 }
4038
4039 // The closing of the inner scope, immediately above, will complete
4040 // logging at the "fine" level. The record_collection_pause_end() call
4041 // above will complete logging at the "finer" level.
4042 //
4043 // It is not yet to safe, however, to tell the concurrent mark to
4044 // start as we have some optional output below. We don't want the
4045 // output from the concurrent mark thread interfering with this
4046 // logging output either.
4047
4048 _hrs.verify_optional();
4049 verify_region_sets_optional();
4050
4051 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4052 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4053
4054 print_heap_after_gc();
4055
4056 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4057 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4058 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4059 // before any GC notifications are raised.
4060 g1mm()->update_sizes();
4061 }
4062
4063 if (G1SummarizeRSetStats &&
4064 (G1SummarizeRSetStatsPeriod > 0) &&
4065 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
4066 g1_rem_set()->print_summary_info();
4067 }
4068
4069 // It should now be safe to tell the concurrent mark thread to start
4070 // without its logging output interfering with the logging output
4071 // that came from the pause.
4072
4073 if (should_start_conc_mark) {
4074 // CAUTION: after the doConcurrentMark() call below,
4075 // the concurrent marking thread(s) could be running
4076 // concurrently with us. Make sure that anything after
4077 // this point does not assume that we are the only GC thread
4078 // running. Note: of course, the actual marking work will
4079 // not start until the safepoint itself is released in
4080 // ConcurrentGCThread::safepoint_desynchronize().
4081 doConcurrentMark();
4082 }
4083
4084 return true;
4085 }
4086
4087 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4088 {
4089 size_t gclab_word_size;
4090 switch (purpose) {
4091 case GCAllocForSurvived:
4092 gclab_word_size = YoungPLABSize;
4093 break;
4094 case GCAllocForTenured:
4095 gclab_word_size = OldPLABSize;
4096 break;
4097 default:
4098 assert(false, "unknown GCAllocPurpose");
4099 gclab_word_size = OldPLABSize;
4100 break;
4101 }
4102 return gclab_word_size;
4103 }
4104
4105 void G1CollectedHeap::init_mutator_alloc_region() {
4106 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4107 _mutator_alloc_region.init();
4108 }
4109
4110 void G1CollectedHeap::release_mutator_alloc_region() {
4111 _mutator_alloc_region.release();
4112 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4113 }
4114
4115 void G1CollectedHeap::init_gc_alloc_regions() {
4116 assert_at_safepoint(true /* should_be_vm_thread */);
4117
4118 _survivor_gc_alloc_region.init();
4119 _old_gc_alloc_region.init();
4120 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4121 _retained_old_gc_alloc_region = NULL;
4122
4123 // We will discard the current GC alloc region if:
4124 // a) it's in the collection set (it can happen!),
4125 // b) it's already full (no point in using it),
4126 // c) it's empty (this means that it was emptied during
4127 // a cleanup and it should be on the free list now), or
4128 // d) it's humongous (this means that it was emptied
4129 // during a cleanup and was added to the free list, but
4130 // has been subseqently used to allocate a humongous
4131 // object that may be less than the region size).
4132 if (retained_region != NULL &&
4133 !retained_region->in_collection_set() &&
4134 !(retained_region->top() == retained_region->end()) &&
4135 !retained_region->is_empty() &&
4136 !retained_region->isHumongous()) {
4137 retained_region->set_saved_mark();
4138 // The retained region was added to the old region set when it was
4139 // retired. We have to remove it now, since we don't allow regions
4140 // we allocate to in the region sets. We'll re-add it later, when
4141 // it's retired again.
4142 _old_set.remove(retained_region);
4143 bool during_im = g1_policy()->during_initial_mark_pause();
4144 retained_region->note_start_of_copying(during_im);
4145 _old_gc_alloc_region.set(retained_region);
4146 _hr_printer.reuse(retained_region);
4147 }
4148 }
4149
4150 void G1CollectedHeap::release_gc_alloc_regions() {
4151 _survivor_gc_alloc_region.release();
4152 // If we have an old GC alloc region to release, we'll save it in
4153 // _retained_old_gc_alloc_region. If we don't
4154 // _retained_old_gc_alloc_region will become NULL. This is what we
4155 // want either way so no reason to check explicitly for either
4156 // condition.
4157 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4158 }
4159
4160 void G1CollectedHeap::abandon_gc_alloc_regions() {
4161 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4162 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4163 _retained_old_gc_alloc_region = NULL;
4164 }
4165
4166 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4167 _drain_in_progress = false;
4168 set_evac_failure_closure(cl);
4169 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4170 }
4171
4172 void G1CollectedHeap::finalize_for_evac_failure() {
4173 assert(_evac_failure_scan_stack != NULL &&
4174 _evac_failure_scan_stack->length() == 0,
4175 "Postcondition");
4176 assert(!_drain_in_progress, "Postcondition");
4177 delete _evac_failure_scan_stack;
4178 _evac_failure_scan_stack = NULL;
4179 }
4180
4181 void G1CollectedHeap::remove_self_forwarding_pointers() {
4182 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4183
4184 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4185
4186 if (G1CollectedHeap::use_parallel_gc_threads()) {
4187 set_par_threads();
4188 workers()->run_task(&rsfp_task);
4189 set_par_threads(0);
4190 } else {
4191 rsfp_task.work(0);
4192 }
4193
4194 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4195
4196 // Reset the claim values in the regions in the collection set.
4197 reset_cset_heap_region_claim_values();
4198
4199 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4200
4201 // Now restore saved marks, if any.
4202 if (_objs_with_preserved_marks != NULL) {
4203 assert(_preserved_marks_of_objs != NULL, "Both or none.");
4204 guarantee(_objs_with_preserved_marks->length() ==
4205 _preserved_marks_of_objs->length(), "Both or none.");
4206 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
4207 oop obj = _objs_with_preserved_marks->at(i);
4208 markOop m = _preserved_marks_of_objs->at(i);
4209 obj->set_mark(m);
4210 }
4211
4212 // Delete the preserved marks growable arrays (allocated on the C heap).
4213 delete _objs_with_preserved_marks;
4214 delete _preserved_marks_of_objs;
4215 _objs_with_preserved_marks = NULL;
4216 _preserved_marks_of_objs = NULL;
4217 }
4218 }
4219
4220 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4221 _evac_failure_scan_stack->push(obj);
4222 }
4223
4224 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4225 assert(_evac_failure_scan_stack != NULL, "precondition");
4226
4227 while (_evac_failure_scan_stack->length() > 0) {
4228 oop obj = _evac_failure_scan_stack->pop();
4229 _evac_failure_closure->set_region(heap_region_containing(obj));
4230 obj->oop_iterate_backwards(_evac_failure_closure);
4231 }
4232 }
4233
4234 oop
4235 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4236 oop old) {
4237 assert(obj_in_cs(old),
4238 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4239 (HeapWord*) old));
4240 markOop m = old->mark();
4241 oop forward_ptr = old->forward_to_atomic(old);
4242 if (forward_ptr == NULL) {
4243 // Forward-to-self succeeded.
4244
4245 if (_evac_failure_closure != cl) {
4246 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4247 assert(!_drain_in_progress,
4248 "Should only be true while someone holds the lock.");
4249 // Set the global evac-failure closure to the current thread's.
4250 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4251 set_evac_failure_closure(cl);
4252 // Now do the common part.
4253 handle_evacuation_failure_common(old, m);
4254 // Reset to NULL.
4255 set_evac_failure_closure(NULL);
4256 } else {
4257 // The lock is already held, and this is recursive.
4258 assert(_drain_in_progress, "This should only be the recursive case.");
4259 handle_evacuation_failure_common(old, m);
4260 }
4261 return old;
4262 } else {
4263 // Forward-to-self failed. Either someone else managed to allocate
4264 // space for this object (old != forward_ptr) or they beat us in
4265 // self-forwarding it (old == forward_ptr).
4266 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4267 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4268 "should not be in the CSet",
4269 (HeapWord*) old, (HeapWord*) forward_ptr));
4270 return forward_ptr;
4271 }
4272 }
4273
4274 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4275 set_evacuation_failed(true);
4276
4277 preserve_mark_if_necessary(old, m);
4278
4279 HeapRegion* r = heap_region_containing(old);
4280 if (!r->evacuation_failed()) {
4281 r->set_evacuation_failed(true);
4282 _hr_printer.evac_failure(r);
4283 }
4284
4285 push_on_evac_failure_scan_stack(old);
4286
4287 if (!_drain_in_progress) {
4288 // prevent recursion in copy_to_survivor_space()
4289 _drain_in_progress = true;
4290 drain_evac_failure_scan_stack();
4291 _drain_in_progress = false;
4292 }
4293 }
4294
4295 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4296 assert(evacuation_failed(), "Oversaving!");
4297 // We want to call the "for_promotion_failure" version only in the
4298 // case of a promotion failure.
4299 if (m->must_be_preserved_for_promotion_failure(obj)) {
4300 if (_objs_with_preserved_marks == NULL) {
4301 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4302 _objs_with_preserved_marks =
4303 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4304 _preserved_marks_of_objs =
4305 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4306 }
4307 _objs_with_preserved_marks->push(obj);
4308 _preserved_marks_of_objs->push(m);
4309 }
4310 }
4311
4312 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4313 size_t word_size) {
4314 if (purpose == GCAllocForSurvived) {
4315 HeapWord* result = survivor_attempt_allocation(word_size);
4316 if (result != NULL) {
4317 return result;
4318 } else {
4319 // Let's try to allocate in the old gen in case we can fit the
4320 // object there.
4321 return old_attempt_allocation(word_size);
4322 }
4323 } else {
4324 assert(purpose == GCAllocForTenured, "sanity");
4325 HeapWord* result = old_attempt_allocation(word_size);
4326 if (result != NULL) {
4327 return result;
4328 } else {
4329 // Let's try to allocate in the survivors in case we can fit the
4330 // object there.
4331 return survivor_attempt_allocation(word_size);
4332 }
4333 }
4334
4335 ShouldNotReachHere();
4336 // Trying to keep some compilers happy.
4337 return NULL;
4338 }
4339
4340 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4341 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4342
4343 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4344 : _g1h(g1h),
4345 _refs(g1h->task_queue(queue_num)),
4346 _dcq(&g1h->dirty_card_queue_set()),
4347 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4348 _g1_rem(g1h->g1_rem_set()),
4349 _hash_seed(17), _queue_num(queue_num),
4350 _term_attempts(0),
4351 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4352 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4353 _age_table(false),
4354 _strong_roots_time(0), _term_time(0),
4355 _alloc_buffer_waste(0), _undo_waste(0) {
4356 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4357 // we "sacrifice" entry 0 to keep track of surviving bytes for
4358 // non-young regions (where the age is -1)
4359 // We also add a few elements at the beginning and at the end in
4360 // an attempt to eliminate cache contention
4361 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4362 uint array_length = PADDING_ELEM_NUM +
4363 real_length +
4364 PADDING_ELEM_NUM;
4365 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4366 if (_surviving_young_words_base == NULL)
4367 vm_exit_out_of_memory(array_length * sizeof(size_t),
4368 "Not enough space for young surv histo.");
4369 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4370 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4371
4372 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4373 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4374
4375 _start = os::elapsedTime();
4376 }
4377
4378 void
4379 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4380 {
4381 st->print_raw_cr("GC Termination Stats");
4382 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4383 " ------waste (KiB)------");
4384 st->print_raw_cr("thr ms ms % ms % attempts"
4385 " total alloc undo");
4386 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4387 " ------- ------- -------");
4388 }
4389
4390 void
4391 G1ParScanThreadState::print_termination_stats(int i,
4392 outputStream* const st) const
4393 {
4394 const double elapsed_ms = elapsed_time() * 1000.0;
4395 const double s_roots_ms = strong_roots_time() * 1000.0;
4396 const double term_ms = term_time() * 1000.0;
4397 st->print_cr("%3d %9.2f %9.2f %6.2f "
4398 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4399 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4400 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4401 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4402 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4403 alloc_buffer_waste() * HeapWordSize / K,
4404 undo_waste() * HeapWordSize / K);
4405 }
4406
4407 #ifdef ASSERT
4408 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4409 assert(ref != NULL, "invariant");
4410 assert(UseCompressedOops, "sanity");
4411 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4412 oop p = oopDesc::load_decode_heap_oop(ref);
4413 assert(_g1h->is_in_g1_reserved(p),
4414 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4415 return true;
4416 }
4417
4418 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4419 assert(ref != NULL, "invariant");
4420 if (has_partial_array_mask(ref)) {
4421 // Must be in the collection set--it's already been copied.
4422 oop p = clear_partial_array_mask(ref);
4423 assert(_g1h->obj_in_cs(p),
4424 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4425 } else {
4426 oop p = oopDesc::load_decode_heap_oop(ref);
4427 assert(_g1h->is_in_g1_reserved(p),
4428 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4429 }
4430 return true;
4431 }
4432
4433 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4434 if (ref.is_narrow()) {
4435 return verify_ref((narrowOop*) ref);
4436 } else {
4437 return verify_ref((oop*) ref);
4438 }
4439 }
4440 #endif // ASSERT
4441
4442 void G1ParScanThreadState::trim_queue() {
4443 assert(_evac_cl != NULL, "not set");
4444 assert(_evac_failure_cl != NULL, "not set");
4445 assert(_partial_scan_cl != NULL, "not set");
4446
4447 StarTask ref;
4448 do {
4449 // Drain the overflow stack first, so other threads can steal.
4450 while (refs()->pop_overflow(ref)) {
4451 deal_with_reference(ref);
4452 }
4453
4454 while (refs()->pop_local(ref)) {
4455 deal_with_reference(ref);
4456 }
4457 } while (!refs()->is_empty());
4458 }
4459
4460 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4461 G1ParScanThreadState* par_scan_state) :
4462 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4463 _par_scan_state(par_scan_state),
4464 _worker_id(par_scan_state->queue_num()),
4465 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4466 _mark_in_progress(_g1->mark_in_progress()) { }
4467
4468 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4469 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4470 #ifdef ASSERT
4471 HeapRegion* hr = _g1->heap_region_containing(obj);
4472 assert(hr != NULL, "sanity");
4473 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4474 #endif // ASSERT
4475
4476 // We know that the object is not moving so it's safe to read its size.
4477 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4478 }
4479
4480 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4481 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4482 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4483 #ifdef ASSERT
4484 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4485 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4486 assert(from_obj != to_obj, "should not be self-forwarded");
4487
4488 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4489 assert(from_hr != NULL, "sanity");
4490 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4491
4492 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4493 assert(to_hr != NULL, "sanity");
4494 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4495 #endif // ASSERT
4496
4497 // The object might be in the process of being copied by another
4498 // worker so we cannot trust that its to-space image is
4499 // well-formed. So we have to read its size from its from-space
4500 // image which we know should not be changing.
4501 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4502 }
4503
4504 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4505 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4506 ::copy_to_survivor_space(oop old) {
4507 size_t word_sz = old->size();
4508 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4509 // +1 to make the -1 indexes valid...
4510 int young_index = from_region->young_index_in_cset()+1;
4511 assert( (from_region->is_young() && young_index > 0) ||
4512 (!from_region->is_young() && young_index == 0), "invariant" );
4513 G1CollectorPolicy* g1p = _g1->g1_policy();
4514 markOop m = old->mark();
4515 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4516 : m->age();
4517 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4518 word_sz);
4519 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4520 oop obj = oop(obj_ptr);
4521
4522 if (obj_ptr == NULL) {
4523 // This will either forward-to-self, or detect that someone else has
4524 // installed a forwarding pointer.
4525 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4526 return _g1->handle_evacuation_failure_par(cl, old);
4527 }
4528
4529 // We're going to allocate linearly, so might as well prefetch ahead.
4530 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4531
4532 oop forward_ptr = old->forward_to_atomic(obj);
4533 if (forward_ptr == NULL) {
4534 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4535 if (g1p->track_object_age(alloc_purpose)) {
4536 // We could simply do obj->incr_age(). However, this causes a
4537 // performance issue. obj->incr_age() will first check whether
4538 // the object has a displaced mark by checking its mark word;
4539 // getting the mark word from the new location of the object
4540 // stalls. So, given that we already have the mark word and we
4541 // are about to install it anyway, it's better to increase the
4542 // age on the mark word, when the object does not have a
4543 // displaced mark word. We're not expecting many objects to have
4544 // a displaced marked word, so that case is not optimized
4545 // further (it could be...) and we simply call obj->incr_age().
4546
4547 if (m->has_displaced_mark_helper()) {
4548 // in this case, we have to install the mark word first,
4549 // otherwise obj looks to be forwarded (the old mark word,
4550 // which contains the forward pointer, was copied)
4551 obj->set_mark(m);
4552 obj->incr_age();
4553 } else {
4554 m = m->incr_age();
4555 obj->set_mark(m);
4556 }
4557 _par_scan_state->age_table()->add(obj, word_sz);
4558 } else {
4559 obj->set_mark(m);
4560 }
4561
4562 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4563 surv_young_words[young_index] += word_sz;
4564
4565 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4566 // We keep track of the next start index in the length field of
4567 // the to-space object. The actual length can be found in the
4568 // length field of the from-space object.
4569 arrayOop(obj)->set_length(0);
4570 oop* old_p = set_partial_array_mask(old);
4571 _par_scan_state->push_on_queue(old_p);
4572 } else {
4573 // No point in using the slower heap_region_containing() method,
4574 // given that we know obj is in the heap.
4575 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4576 obj->oop_iterate_backwards(&_scanner);
4577 }
4578 } else {
4579 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4580 obj = forward_ptr;
4581 }
4582 return obj;
4583 }
4584
4585 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4586 template <class T>
4587 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4588 ::do_oop_work(T* p) {
4589 oop obj = oopDesc::load_decode_heap_oop(p);
4590 assert(barrier != G1BarrierRS || obj != NULL,
4591 "Precondition: G1BarrierRS implies obj is non-NULL");
4592
4593 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4594
4595 // here the null check is implicit in the cset_fast_test() test
4596 if (_g1->in_cset_fast_test(obj)) {
4597 oop forwardee;
4598 if (obj->is_forwarded()) {
4599 forwardee = obj->forwardee();
4600 } else {
4601 forwardee = copy_to_survivor_space(obj);
4602 }
4603 assert(forwardee != NULL, "forwardee should not be NULL");
4604 oopDesc::encode_store_heap_oop(p, forwardee);
4605 if (do_mark_object && forwardee != obj) {
4606 // If the object is self-forwarded we don't need to explicitly
4607 // mark it, the evacuation failure protocol will do so.
4608 mark_forwarded_object(obj, forwardee);
4609 }
4610
4611 // When scanning the RS, we only care about objs in CS.
4612 if (barrier == G1BarrierRS) {
4613 _par_scan_state->update_rs(_from, p, _worker_id);
4614 }
4615 } else {
4616 // The object is not in collection set. If we're a root scanning
4617 // closure during an initial mark pause (i.e. do_mark_object will
4618 // be true) then attempt to mark the object.
4619 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4620 mark_object(obj);
4621 }
4622 }
4623
4624 if (barrier == G1BarrierEvac && obj != NULL) {
4625 _par_scan_state->update_rs(_from, p, _worker_id);
4626 }
4627
4628 if (do_gen_barrier && obj != NULL) {
4629 par_do_barrier(p);
4630 }
4631 }
4632
4633 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4634 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4635
4636 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4637 assert(has_partial_array_mask(p), "invariant");
4638 oop from_obj = clear_partial_array_mask(p);
4639
4640 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4641 assert(from_obj->is_objArray(), "must be obj array");
4642 objArrayOop from_obj_array = objArrayOop(from_obj);
4643 // The from-space object contains the real length.
4644 int length = from_obj_array->length();
4645
4646 assert(from_obj->is_forwarded(), "must be forwarded");
4647 oop to_obj = from_obj->forwardee();
4648 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4649 objArrayOop to_obj_array = objArrayOop(to_obj);
4650 // We keep track of the next start index in the length field of the
4651 // to-space object.
4652 int next_index = to_obj_array->length();
4653 assert(0 <= next_index && next_index < length,
4654 err_msg("invariant, next index: %d, length: %d", next_index, length));
4655
4656 int start = next_index;
4657 int end = length;
4658 int remainder = end - start;
4659 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4660 if (remainder > 2 * ParGCArrayScanChunk) {
4661 end = start + ParGCArrayScanChunk;
4662 to_obj_array->set_length(end);
4663 // Push the remainder before we process the range in case another
4664 // worker has run out of things to do and can steal it.
4665 oop* from_obj_p = set_partial_array_mask(from_obj);
4666 _par_scan_state->push_on_queue(from_obj_p);
4667 } else {
4668 assert(length == end, "sanity");
4669 // We'll process the final range for this object. Restore the length
4670 // so that the heap remains parsable in case of evacuation failure.
4671 to_obj_array->set_length(end);
4672 }
4673 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4674 // Process indexes [start,end). It will also process the header
4675 // along with the first chunk (i.e., the chunk with start == 0).
4676 // Note that at this point the length field of to_obj_array is not
4677 // correct given that we are using it to keep track of the next
4678 // start index. oop_iterate_range() (thankfully!) ignores the length
4679 // field and only relies on the start / end parameters. It does
4680 // however return the size of the object which will be incorrect. So
4681 // we have to ignore it even if we wanted to use it.
4682 to_obj_array->oop_iterate_range(&_scanner, start, end);
4683 }
4684
4685 class G1ParEvacuateFollowersClosure : public VoidClosure {
4686 protected:
4687 G1CollectedHeap* _g1h;
4688 G1ParScanThreadState* _par_scan_state;
4689 RefToScanQueueSet* _queues;
4690 ParallelTaskTerminator* _terminator;
4691
4692 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4693 RefToScanQueueSet* queues() { return _queues; }
4694 ParallelTaskTerminator* terminator() { return _terminator; }
4695
4696 public:
4697 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4698 G1ParScanThreadState* par_scan_state,
4699 RefToScanQueueSet* queues,
4700 ParallelTaskTerminator* terminator)
4701 : _g1h(g1h), _par_scan_state(par_scan_state),
4702 _queues(queues), _terminator(terminator) {}
4703
4704 void do_void();
4705
4706 private:
4707 inline bool offer_termination();
4708 };
4709
4710 bool G1ParEvacuateFollowersClosure::offer_termination() {
4711 G1ParScanThreadState* const pss = par_scan_state();
4712 pss->start_term_time();
4713 const bool res = terminator()->offer_termination();
4714 pss->end_term_time();
4715 return res;
4716 }
4717
4718 void G1ParEvacuateFollowersClosure::do_void() {
4719 StarTask stolen_task;
4720 G1ParScanThreadState* const pss = par_scan_state();
4721 pss->trim_queue();
4722
4723 do {
4724 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4725 assert(pss->verify_task(stolen_task), "sanity");
4726 if (stolen_task.is_narrow()) {
4727 pss->deal_with_reference((narrowOop*) stolen_task);
4728 } else {
4729 pss->deal_with_reference((oop*) stolen_task);
4730 }
4731
4732 // We've just processed a reference and we might have made
4733 // available new entries on the queues. So we have to make sure
4734 // we drain the queues as necessary.
4735 pss->trim_queue();
4736 }
4737 } while (!offer_termination());
4738
4739 pss->retire_alloc_buffers();
4740 }
4741
4742 class G1ParTask : public AbstractGangTask {
4743 protected:
4744 G1CollectedHeap* _g1h;
4745 RefToScanQueueSet *_queues;
4746 ParallelTaskTerminator _terminator;
4747 uint _n_workers;
4748
4749 Mutex _stats_lock;
4750 Mutex* stats_lock() { return &_stats_lock; }
4751
4752 size_t getNCards() {
4753 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4754 / G1BlockOffsetSharedArray::N_bytes;
4755 }
4756
4757 public:
4758 G1ParTask(G1CollectedHeap* g1h,
4759 RefToScanQueueSet *task_queues)
4760 : AbstractGangTask("G1 collection"),
4761 _g1h(g1h),
4762 _queues(task_queues),
4763 _terminator(0, _queues),
4764 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4765 {}
4766
4767 RefToScanQueueSet* queues() { return _queues; }
4768
4769 RefToScanQueue *work_queue(int i) {
4770 return queues()->queue(i);
4771 }
4772
4773 ParallelTaskTerminator* terminator() { return &_terminator; }
4774
4775 virtual void set_for_termination(int active_workers) {
4776 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4777 // in the young space (_par_seq_tasks) in the G1 heap
4778 // for SequentialSubTasksDone.
4779 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4780 // both of which need setting by set_n_termination().
4781 _g1h->SharedHeap::set_n_termination(active_workers);
4782 _g1h->set_n_termination(active_workers);
4783 terminator()->reset_for_reuse(active_workers);
4784 _n_workers = active_workers;
4785 }
4786
4787 void work(uint worker_id) {
4788 if (worker_id >= _n_workers) return; // no work needed this round
4789
4790 double start_time_ms = os::elapsedTime() * 1000.0;
4791 _g1h->g1_policy()->record_gc_worker_start_time(worker_id, start_time_ms);
4792
4793 {
4794 ResourceMark rm;
4795 HandleMark hm;
4796
4797 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4798
4799 G1ParScanThreadState pss(_g1h, worker_id);
4800 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4801 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4802 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4803
4804 pss.set_evac_closure(&scan_evac_cl);
4805 pss.set_evac_failure_closure(&evac_failure_cl);
4806 pss.set_partial_scan_closure(&partial_scan_cl);
4807
4808 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4809 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp);
4810
4811 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4812 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp);
4813
4814 OopClosure* scan_root_cl = &only_scan_root_cl;
4815 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl;
4816
4817 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4818 // We also need to mark copied objects.
4819 scan_root_cl = &scan_mark_root_cl;
4820 scan_perm_cl = &scan_mark_perm_cl;
4821 }
4822
4823 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4824
4825 pss.start_strong_roots();
4826 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4827 SharedHeap::SO_AllClasses,
4828 scan_root_cl,
4829 &push_heap_rs_cl,
4830 scan_perm_cl,
4831 worker_id);
4832 pss.end_strong_roots();
4833
4834 {
4835 double start = os::elapsedTime();
4836 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4837 evac.do_void();
4838 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4839 double term_ms = pss.term_time()*1000.0;
4840 _g1h->g1_policy()->record_obj_copy_time(worker_id, elapsed_ms-term_ms);
4841 _g1h->g1_policy()->record_termination(worker_id, term_ms, pss.term_attempts());
4842 }
4843 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4844 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4845
4846 if (ParallelGCVerbose) {
4847 MutexLocker x(stats_lock());
4848 pss.print_termination_stats(worker_id);
4849 }
4850
4851 assert(pss.refs()->is_empty(), "should be empty");
4852
4853 // Close the inner scope so that the ResourceMark and HandleMark
4854 // destructors are executed here and are included as part of the
4855 // "GC Worker Time".
4856 }
4857
4858 double end_time_ms = os::elapsedTime() * 1000.0;
4859 _g1h->g1_policy()->record_gc_worker_end_time(worker_id, end_time_ms);
4860 }
4861 };
4862
4863 // *** Common G1 Evacuation Stuff
4864
4865 // Closures that support the filtering of CodeBlobs scanned during
4866 // external root scanning.
4867
4868 // Closure applied to reference fields in code blobs (specifically nmethods)
4869 // to determine whether an nmethod contains references that point into
4870 // the collection set. Used as a predicate when walking code roots so
4871 // that only nmethods that point into the collection set are added to the
4872 // 'marked' list.
4873
4874 class G1FilteredCodeBlobToOopClosure : public CodeBlobToOopClosure {
4875
4876 class G1PointsIntoCSOopClosure : public OopClosure {
4877 G1CollectedHeap* _g1;
4878 bool _points_into_cs;
4879 public:
4880 G1PointsIntoCSOopClosure(G1CollectedHeap* g1) :
4881 _g1(g1), _points_into_cs(false) { }
4882
4883 bool points_into_cs() const { return _points_into_cs; }
4884
4885 template <class T>
4886 void do_oop_nv(T* p) {
4887 if (!_points_into_cs) {
4888 T heap_oop = oopDesc::load_heap_oop(p);
4889 if (!oopDesc::is_null(heap_oop) &&
4890 _g1->in_cset_fast_test(oopDesc::decode_heap_oop_not_null(heap_oop))) {
4891 _points_into_cs = true;
4892 }
4893 }
4894 }
4895
4896 virtual void do_oop(oop* p) { do_oop_nv(p); }
4897 virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
4898 };
4899
4900 G1CollectedHeap* _g1;
4901
4902 public:
4903 G1FilteredCodeBlobToOopClosure(G1CollectedHeap* g1, OopClosure* cl) :
4904 CodeBlobToOopClosure(cl, true), _g1(g1) { }
4905
4906 virtual void do_code_blob(CodeBlob* cb) {
4907 nmethod* nm = cb->as_nmethod_or_null();
4908 if (nm != NULL && !(nm->test_oops_do_mark())) {
4909 G1PointsIntoCSOopClosure predicate_cl(_g1);
4910 nm->oops_do(&predicate_cl);
4911
4912 if (predicate_cl.points_into_cs()) {
4913 // At least one of the reference fields or the oop relocations
4914 // in the nmethod points into the collection set. We have to
4915 // 'mark' this nmethod.
4916 // Note: Revisit the following if CodeBlobToOopClosure::do_code_blob()
4917 // or MarkingCodeBlobClosure::do_code_blob() change.
4918 if (!nm->test_set_oops_do_mark()) {
4919 do_newly_marked_nmethod(nm);
4920 }
4921 }
4922 }
4923 }
4924 };
4925
4926 // This method is run in a GC worker.
4927
4928 void
4929 G1CollectedHeap::
4930 g1_process_strong_roots(bool collecting_perm_gen,
4931 ScanningOption so,
4932 OopClosure* scan_non_heap_roots,
4933 OopsInHeapRegionClosure* scan_rs,
4934 OopsInGenClosure* scan_perm,
4935 int worker_i) {
4936
4937 // First scan the strong roots, including the perm gen.
4938 double ext_roots_start = os::elapsedTime();
4939 double closure_app_time_sec = 0.0;
4940
4941 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4942 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4943 buf_scan_perm.set_generation(perm_gen());
4944
4945 // Walk the code cache w/o buffering, because StarTask cannot handle
4946 // unaligned oop locations.
4947 G1FilteredCodeBlobToOopClosure eager_scan_code_roots(this, scan_non_heap_roots);
4948
4949 process_strong_roots(false, // no scoping; this is parallel code
4950 collecting_perm_gen, so,
4951 &buf_scan_non_heap_roots,
4952 &eager_scan_code_roots,
4953 &buf_scan_perm);
4954
4955 // Now the CM ref_processor roots.
4956 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4957 // We need to treat the discovered reference lists of the
4958 // concurrent mark ref processor as roots and keep entries
4959 // (which are added by the marking threads) on them live
4960 // until they can be processed at the end of marking.
4961 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4962 }
4963
4964 // Finish up any enqueued closure apps (attributed as object copy time).
4965 buf_scan_non_heap_roots.done();
4966 buf_scan_perm.done();
4967
4968 double ext_roots_end = os::elapsedTime();
4969
4970 g1_policy()->reset_obj_copy_time(worker_i);
4971 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4972 buf_scan_non_heap_roots.closure_app_seconds();
4973 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4974
4975 double ext_root_time_ms =
4976 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4977
4978 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4979
4980 // During conc marking we have to filter the per-thread SATB buffers
4981 // to make sure we remove any oops into the CSet (which will show up
4982 // as implicitly live).
4983 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4984 if (mark_in_progress()) {
4985 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4986 }
4987 }
4988 double satb_filtering_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4989 g1_policy()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4990
4991 // Now scan the complement of the collection set.
4992 if (scan_rs != NULL) {
4993 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4994 }
4995
4996 _process_strong_tasks->all_tasks_completed();
4997 }
4998
4999 void
5000 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
5001 OopClosure* non_root_closure) {
5002 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5003 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
5004 }
5005
5006 // Weak Reference Processing support
5007
5008 // An always "is_alive" closure that is used to preserve referents.
5009 // If the object is non-null then it's alive. Used in the preservation
5010 // of referent objects that are pointed to by reference objects
5011 // discovered by the CM ref processor.
5012 class G1AlwaysAliveClosure: public BoolObjectClosure {
5013 G1CollectedHeap* _g1;
5014 public:
5015 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5016 void do_object(oop p) { assert(false, "Do not call."); }
5017 bool do_object_b(oop p) {
5018 if (p != NULL) {
5019 return true;
5020 }
5021 return false;
5022 }
5023 };
5024
5025 bool G1STWIsAliveClosure::do_object_b(oop p) {
5026 // An object is reachable if it is outside the collection set,
5027 // or is inside and copied.
5028 return !_g1->obj_in_cs(p) || p->is_forwarded();
5029 }
5030
5031 // Non Copying Keep Alive closure
5032 class G1KeepAliveClosure: public OopClosure {
5033 G1CollectedHeap* _g1;
5034 public:
5035 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5036 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5037 void do_oop( oop* p) {
5038 oop obj = *p;
5039
5040 if (_g1->obj_in_cs(obj)) {
5041 assert( obj->is_forwarded(), "invariant" );
5042 *p = obj->forwardee();
5043 }
5044 }
5045 };
5046
5047 // Copying Keep Alive closure - can be called from both
5048 // serial and parallel code as long as different worker
5049 // threads utilize different G1ParScanThreadState instances
5050 // and different queues.
5051
5052 class G1CopyingKeepAliveClosure: public OopClosure {
5053 G1CollectedHeap* _g1h;
5054 OopClosure* _copy_non_heap_obj_cl;
5055 OopsInHeapRegionClosure* _copy_perm_obj_cl;
5056 G1ParScanThreadState* _par_scan_state;
5057
5058 public:
5059 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5060 OopClosure* non_heap_obj_cl,
5061 OopsInHeapRegionClosure* perm_obj_cl,
5062 G1ParScanThreadState* pss):
5063 _g1h(g1h),
5064 _copy_non_heap_obj_cl(non_heap_obj_cl),
5065 _copy_perm_obj_cl(perm_obj_cl),
5066 _par_scan_state(pss)
5067 {}
5068
5069 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5070 virtual void do_oop( oop* p) { do_oop_work(p); }
5071
5072 template <class T> void do_oop_work(T* p) {
5073 oop obj = oopDesc::load_decode_heap_oop(p);
5074
5075 if (_g1h->obj_in_cs(obj)) {
5076 // If the referent object has been forwarded (either copied
5077 // to a new location or to itself in the event of an
5078 // evacuation failure) then we need to update the reference
5079 // field and, if both reference and referent are in the G1
5080 // heap, update the RSet for the referent.
5081 //
5082 // If the referent has not been forwarded then we have to keep
5083 // it alive by policy. Therefore we have copy the referent.
5084 //
5085 // If the reference field is in the G1 heap then we can push
5086 // on the PSS queue. When the queue is drained (after each
5087 // phase of reference processing) the object and it's followers
5088 // will be copied, the reference field set to point to the
5089 // new location, and the RSet updated. Otherwise we need to
5090 // use the the non-heap or perm closures directly to copy
5091 // the refernt object and update the pointer, while avoiding
5092 // updating the RSet.
5093
5094 if (_g1h->is_in_g1_reserved(p)) {
5095 _par_scan_state->push_on_queue(p);
5096 } else {
5097 // The reference field is not in the G1 heap.
5098 if (_g1h->perm_gen()->is_in(p)) {
5099 _copy_perm_obj_cl->do_oop(p);
5100 } else {
5101 _copy_non_heap_obj_cl->do_oop(p);
5102 }
5103 }
5104 }
5105 }
5106 };
5107
5108 // Serial drain queue closure. Called as the 'complete_gc'
5109 // closure for each discovered list in some of the
5110 // reference processing phases.
5111
5112 class G1STWDrainQueueClosure: public VoidClosure {
5113 protected:
5114 G1CollectedHeap* _g1h;
5115 G1ParScanThreadState* _par_scan_state;
5116
5117 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5118
5119 public:
5120 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5121 _g1h(g1h),
5122 _par_scan_state(pss)
5123 { }
5124
5125 void do_void() {
5126 G1ParScanThreadState* const pss = par_scan_state();
5127 pss->trim_queue();
5128 }
5129 };
5130
5131 // Parallel Reference Processing closures
5132
5133 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5134 // processing during G1 evacuation pauses.
5135
5136 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5137 private:
5138 G1CollectedHeap* _g1h;
5139 RefToScanQueueSet* _queues;
5140 FlexibleWorkGang* _workers;
5141 int _active_workers;
5142
5143 public:
5144 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5145 FlexibleWorkGang* workers,
5146 RefToScanQueueSet *task_queues,
5147 int n_workers) :
5148 _g1h(g1h),
5149 _queues(task_queues),
5150 _workers(workers),
5151 _active_workers(n_workers)
5152 {
5153 assert(n_workers > 0, "shouldn't call this otherwise");
5154 }
5155
5156 // Executes the given task using concurrent marking worker threads.
5157 virtual void execute(ProcessTask& task);
5158 virtual void execute(EnqueueTask& task);
5159 };
5160
5161 // Gang task for possibly parallel reference processing
5162
5163 class G1STWRefProcTaskProxy: public AbstractGangTask {
5164 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5165 ProcessTask& _proc_task;
5166 G1CollectedHeap* _g1h;
5167 RefToScanQueueSet *_task_queues;
5168 ParallelTaskTerminator* _terminator;
5169
5170 public:
5171 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5172 G1CollectedHeap* g1h,
5173 RefToScanQueueSet *task_queues,
5174 ParallelTaskTerminator* terminator) :
5175 AbstractGangTask("Process reference objects in parallel"),
5176 _proc_task(proc_task),
5177 _g1h(g1h),
5178 _task_queues(task_queues),
5179 _terminator(terminator)
5180 {}
5181
5182 virtual void work(uint worker_id) {
5183 // The reference processing task executed by a single worker.
5184 ResourceMark rm;
5185 HandleMark hm;
5186
5187 G1STWIsAliveClosure is_alive(_g1h);
5188
5189 G1ParScanThreadState pss(_g1h, worker_id);
5190
5191 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5192 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5193 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5194
5195 pss.set_evac_closure(&scan_evac_cl);
5196 pss.set_evac_failure_closure(&evac_failure_cl);
5197 pss.set_partial_scan_closure(&partial_scan_cl);
5198
5199 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5200 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5201
5202 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5203 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5204
5205 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5206 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5207
5208 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5209 // We also need to mark copied objects.
5210 copy_non_heap_cl = ©_mark_non_heap_cl;
5211 copy_perm_cl = ©_mark_perm_cl;
5212 }
5213
5214 // Keep alive closure.
5215 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5216
5217 // Complete GC closure
5218 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5219
5220 // Call the reference processing task's work routine.
5221 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5222
5223 // Note we cannot assert that the refs array is empty here as not all
5224 // of the processing tasks (specifically phase2 - pp2_work) execute
5225 // the complete_gc closure (which ordinarily would drain the queue) so
5226 // the queue may not be empty.
5227 }
5228 };
5229
5230 // Driver routine for parallel reference processing.
5231 // Creates an instance of the ref processing gang
5232 // task and has the worker threads execute it.
5233 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5234 assert(_workers != NULL, "Need parallel worker threads.");
5235
5236 ParallelTaskTerminator terminator(_active_workers, _queues);
5237 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5238
5239 _g1h->set_par_threads(_active_workers);
5240 _workers->run_task(&proc_task_proxy);
5241 _g1h->set_par_threads(0);
5242 }
5243
5244 // Gang task for parallel reference enqueueing.
5245
5246 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5247 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5248 EnqueueTask& _enq_task;
5249
5250 public:
5251 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5252 AbstractGangTask("Enqueue reference objects in parallel"),
5253 _enq_task(enq_task)
5254 { }
5255
5256 virtual void work(uint worker_id) {
5257 _enq_task.work(worker_id);
5258 }
5259 };
5260
5261 // Driver routine for parallel reference enqueing.
5262 // Creates an instance of the ref enqueueing gang
5263 // task and has the worker threads execute it.
5264
5265 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5266 assert(_workers != NULL, "Need parallel worker threads.");
5267
5268 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5269
5270 _g1h->set_par_threads(_active_workers);
5271 _workers->run_task(&enq_task_proxy);
5272 _g1h->set_par_threads(0);
5273 }
5274
5275 // End of weak reference support closures
5276
5277 // Abstract task used to preserve (i.e. copy) any referent objects
5278 // that are in the collection set and are pointed to by reference
5279 // objects discovered by the CM ref processor.
5280
5281 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5282 protected:
5283 G1CollectedHeap* _g1h;
5284 RefToScanQueueSet *_queues;
5285 ParallelTaskTerminator _terminator;
5286 uint _n_workers;
5287
5288 public:
5289 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5290 AbstractGangTask("ParPreserveCMReferents"),
5291 _g1h(g1h),
5292 _queues(task_queues),
5293 _terminator(workers, _queues),
5294 _n_workers(workers)
5295 { }
5296
5297 void work(uint worker_id) {
5298 ResourceMark rm;
5299 HandleMark hm;
5300
5301 G1ParScanThreadState pss(_g1h, worker_id);
5302 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5303 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5304 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5305
5306 pss.set_evac_closure(&scan_evac_cl);
5307 pss.set_evac_failure_closure(&evac_failure_cl);
5308 pss.set_partial_scan_closure(&partial_scan_cl);
5309
5310 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5311
5312
5313 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5314 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5315
5316 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5317 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5318
5319 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5320 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5321
5322 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5323 // We also need to mark copied objects.
5324 copy_non_heap_cl = ©_mark_non_heap_cl;
5325 copy_perm_cl = ©_mark_perm_cl;
5326 }
5327
5328 // Is alive closure
5329 G1AlwaysAliveClosure always_alive(_g1h);
5330
5331 // Copying keep alive closure. Applied to referent objects that need
5332 // to be copied.
5333 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5334
5335 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5336
5337 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5338 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5339
5340 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5341 // So this must be true - but assert just in case someone decides to
5342 // change the worker ids.
5343 assert(0 <= worker_id && worker_id < limit, "sanity");
5344 assert(!rp->discovery_is_atomic(), "check this code");
5345
5346 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5347 for (uint idx = worker_id; idx < limit; idx += stride) {
5348 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5349
5350 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5351 while (iter.has_next()) {
5352 // Since discovery is not atomic for the CM ref processor, we
5353 // can see some null referent objects.
5354 iter.load_ptrs(DEBUG_ONLY(true));
5355 oop ref = iter.obj();
5356
5357 // This will filter nulls.
5358 if (iter.is_referent_alive()) {
5359 iter.make_referent_alive();
5360 }
5361 iter.move_to_next();
5362 }
5363 }
5364
5365 // Drain the queue - which may cause stealing
5366 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5367 drain_queue.do_void();
5368 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5369 assert(pss.refs()->is_empty(), "should be");
5370 }
5371 };
5372
5373 // Weak Reference processing during an evacuation pause (part 1).
5374 void G1CollectedHeap::process_discovered_references() {
5375 double ref_proc_start = os::elapsedTime();
5376
5377 ReferenceProcessor* rp = _ref_processor_stw;
5378 assert(rp->discovery_enabled(), "should have been enabled");
5379
5380 // Any reference objects, in the collection set, that were 'discovered'
5381 // by the CM ref processor should have already been copied (either by
5382 // applying the external root copy closure to the discovered lists, or
5383 // by following an RSet entry).
5384 //
5385 // But some of the referents, that are in the collection set, that these
5386 // reference objects point to may not have been copied: the STW ref
5387 // processor would have seen that the reference object had already
5388 // been 'discovered' and would have skipped discovering the reference,
5389 // but would not have treated the reference object as a regular oop.
5390 // As a reult the copy closure would not have been applied to the
5391 // referent object.
5392 //
5393 // We need to explicitly copy these referent objects - the references
5394 // will be processed at the end of remarking.
5395 //
5396 // We also need to do this copying before we process the reference
5397 // objects discovered by the STW ref processor in case one of these
5398 // referents points to another object which is also referenced by an
5399 // object discovered by the STW ref processor.
5400
5401 uint active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5402 workers()->active_workers() : 1);
5403
5404 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5405 active_workers == workers()->active_workers(),
5406 "Need to reset active_workers");
5407
5408 set_par_threads(active_workers);
5409 G1ParPreserveCMReferentsTask keep_cm_referents(this, active_workers, _task_queues);
5410
5411 if (G1CollectedHeap::use_parallel_gc_threads()) {
5412 workers()->run_task(&keep_cm_referents);
5413 } else {
5414 keep_cm_referents.work(0);
5415 }
5416
5417 set_par_threads(0);
5418
5419 // Closure to test whether a referent is alive.
5420 G1STWIsAliveClosure is_alive(this);
5421
5422 // Even when parallel reference processing is enabled, the processing
5423 // of JNI refs is serial and performed serially by the current thread
5424 // rather than by a worker. The following PSS will be used for processing
5425 // JNI refs.
5426
5427 // Use only a single queue for this PSS.
5428 G1ParScanThreadState pss(this, 0);
5429
5430 // We do not embed a reference processor in the copying/scanning
5431 // closures while we're actually processing the discovered
5432 // reference objects.
5433 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5434 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5435 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5436
5437 pss.set_evac_closure(&scan_evac_cl);
5438 pss.set_evac_failure_closure(&evac_failure_cl);
5439 pss.set_partial_scan_closure(&partial_scan_cl);
5440
5441 assert(pss.refs()->is_empty(), "pre-condition");
5442
5443 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5444 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL);
5445
5446 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5447 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL);
5448
5449 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5450 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5451
5452 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5453 // We also need to mark copied objects.
5454 copy_non_heap_cl = ©_mark_non_heap_cl;
5455 copy_perm_cl = ©_mark_perm_cl;
5456 }
5457
5458 // Keep alive closure.
5459 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5460
5461 // Serial Complete GC closure
5462 G1STWDrainQueueClosure drain_queue(this, &pss);
5463
5464 // Setup the soft refs policy...
5465 rp->setup_policy(false);
5466
5467 if (!rp->processing_is_mt()) {
5468 // Serial reference processing...
5469 rp->process_discovered_references(&is_alive,
5470 &keep_alive,
5471 &drain_queue,
5472 NULL);
5473 } else {
5474 // Parallel reference processing
5475 assert(rp->num_q() == active_workers, "sanity");
5476 assert(active_workers <= rp->max_num_q(), "sanity");
5477
5478 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5479 rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5480 }
5481
5482 // We have completed copying any necessary live referent objects
5483 // (that were not copied during the actual pause) so we can
5484 // retire any active alloc buffers
5485 pss.retire_alloc_buffers();
5486 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5487
5488 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5489 g1_policy()->record_ref_proc_time(ref_proc_time * 1000.0);
5490 }
5491
5492 // Weak Reference processing during an evacuation pause (part 2).
5493 void G1CollectedHeap::enqueue_discovered_references() {
5494 double ref_enq_start = os::elapsedTime();
5495
5496 ReferenceProcessor* rp = _ref_processor_stw;
5497 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5498
5499 // Now enqueue any remaining on the discovered lists on to
5500 // the pending list.
5501 if (!rp->processing_is_mt()) {
5502 // Serial reference processing...
5503 rp->enqueue_discovered_references();
5504 } else {
5505 // Parallel reference enqueuing
5506
5507 uint active_workers = (ParallelGCThreads > 0 ? workers()->active_workers() : 1);
5508 assert(active_workers == workers()->active_workers(),
5509 "Need to reset active_workers");
5510 assert(rp->num_q() == active_workers, "sanity");
5511 assert(active_workers <= rp->max_num_q(), "sanity");
5512
5513 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5514 rp->enqueue_discovered_references(&par_task_executor);
5515 }
5516
5517 rp->verify_no_references_recorded();
5518 assert(!rp->discovery_enabled(), "should have been disabled");
5519
5520 // FIXME
5521 // CM's reference processing also cleans up the string and symbol tables.
5522 // Should we do that here also? We could, but it is a serial operation
5523 // and could signicantly increase the pause time.
5524
5525 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5526 g1_policy()->record_ref_enq_time(ref_enq_time * 1000.0);
5527 }
5528
5529 void G1CollectedHeap::evacuate_collection_set() {
5530 _expand_heap_after_alloc_failure = true;
5531 set_evacuation_failed(false);
5532
5533 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5534 concurrent_g1_refine()->set_use_cache(false);
5535 concurrent_g1_refine()->clear_hot_cache_claimed_index();
5536
5537 uint n_workers;
5538 if (G1CollectedHeap::use_parallel_gc_threads()) {
5539 n_workers =
5540 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5541 workers()->active_workers(),
5542 Threads::number_of_non_daemon_threads());
5543 assert(UseDynamicNumberOfGCThreads ||
5544 n_workers == workers()->total_workers(),
5545 "If not dynamic should be using all the workers");
5546 workers()->set_active_workers(n_workers);
5547 set_par_threads(n_workers);
5548 } else {
5549 assert(n_par_threads() == 0,
5550 "Should be the original non-parallel value");
5551 n_workers = 1;
5552 }
5553
5554 G1ParTask g1_par_task(this, _task_queues);
5555
5556 init_for_evac_failure(NULL);
5557
5558 rem_set()->prepare_for_younger_refs_iterate(true);
5559
5560 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5561 double start_par_time_sec = os::elapsedTime();
5562 double end_par_time_sec;
5563
5564 {
5565 StrongRootsScope srs(this);
5566
5567 if (G1CollectedHeap::use_parallel_gc_threads()) {
5568 // The individual threads will set their evac-failure closures.
5569 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5570 // These tasks use ShareHeap::_process_strong_tasks
5571 assert(UseDynamicNumberOfGCThreads ||
5572 workers()->active_workers() == workers()->total_workers(),
5573 "If not dynamic should be using all the workers");
5574 workers()->run_task(&g1_par_task);
5575 } else {
5576 g1_par_task.set_for_termination(n_workers);
5577 g1_par_task.work(0);
5578 }
5579 end_par_time_sec = os::elapsedTime();
5580
5581 // Closing the inner scope will execute the destructor
5582 // for the StrongRootsScope object. We record the current
5583 // elapsed time before closing the scope so that time
5584 // taken for the SRS destructor is NOT included in the
5585 // reported parallel time.
5586 }
5587
5588 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5589 g1_policy()->record_par_time(par_time_ms);
5590
5591 double code_root_fixup_time_ms =
5592 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5593 g1_policy()->record_code_root_fixup_time(code_root_fixup_time_ms);
5594
5595 set_par_threads(0);
5596
5597 // Process any discovered reference objects - we have
5598 // to do this _before_ we retire the GC alloc regions
5599 // as we may have to copy some 'reachable' referent
5600 // objects (and their reachable sub-graphs) that were
5601 // not copied during the pause.
5602 process_discovered_references();
5603
5604 // Weak root processing.
5605 // Note: when JSR 292 is enabled and code blobs can contain
5606 // non-perm oops then we will need to process the code blobs
5607 // here too.
5608 {
5609 G1STWIsAliveClosure is_alive(this);
5610 G1KeepAliveClosure keep_alive(this);
5611 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5612 }
5613
5614 release_gc_alloc_regions();
5615 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5616
5617 concurrent_g1_refine()->clear_hot_cache();
5618 concurrent_g1_refine()->set_use_cache(true);
5619
5620 finalize_for_evac_failure();
5621
5622 if (evacuation_failed()) {
5623 remove_self_forwarding_pointers();
5624 if (G1Log::finer()) {
5625 gclog_or_tty->print(" (to-space exhausted)");
5626 } else if (G1Log::fine()) {
5627 gclog_or_tty->print("--");
5628 }
5629 }
5630
5631 // Enqueue any remaining references remaining on the STW
5632 // reference processor's discovered lists. We need to do
5633 // this after the card table is cleaned (and verified) as
5634 // the act of enqueuing entries on to the pending list
5635 // will log these updates (and dirty their associated
5636 // cards). We need these updates logged to update any
5637 // RSets.
5638 enqueue_discovered_references();
5639
5640 if (G1DeferredRSUpdate) {
5641 RedirtyLoggedCardTableEntryFastClosure redirty;
5642 dirty_card_queue_set().set_closure(&redirty);
5643 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5644
5645 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5646 dcq.merge_bufferlists(&dirty_card_queue_set());
5647 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5648 }
5649 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5650 }
5651
5652 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5653 size_t* pre_used,
5654 FreeRegionList* free_list,
5655 OldRegionSet* old_proxy_set,
5656 HumongousRegionSet* humongous_proxy_set,
5657 HRRSCleanupTask* hrrs_cleanup_task,
5658 bool par) {
5659 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5660 if (hr->isHumongous()) {
5661 assert(hr->startsHumongous(), "we should only see starts humongous");
5662 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5663 } else {
5664 _old_set.remove_with_proxy(hr, old_proxy_set);
5665 free_region(hr, pre_used, free_list, par);
5666 }
5667 } else {
5668 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5669 }
5670 }
5671
5672 void G1CollectedHeap::free_region(HeapRegion* hr,
5673 size_t* pre_used,
5674 FreeRegionList* free_list,
5675 bool par) {
5676 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5677 assert(!hr->is_empty(), "the region should not be empty");
5678 assert(free_list != NULL, "pre-condition");
5679
5680 *pre_used += hr->used();
5681 hr->hr_clear(par, true /* clear_space */);
5682 free_list->add_as_head(hr);
5683 }
5684
5685 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5686 size_t* pre_used,
5687 FreeRegionList* free_list,
5688 HumongousRegionSet* humongous_proxy_set,
5689 bool par) {
5690 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5691 assert(free_list != NULL, "pre-condition");
5692 assert(humongous_proxy_set != NULL, "pre-condition");
5693
5694 size_t hr_used = hr->used();
5695 size_t hr_capacity = hr->capacity();
5696 size_t hr_pre_used = 0;
5697 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5698 // We need to read this before we make the region non-humongous,
5699 // otherwise the information will be gone.
5700 uint last_index = hr->last_hc_index();
5701 hr->set_notHumongous();
5702 free_region(hr, &hr_pre_used, free_list, par);
5703
5704 uint i = hr->hrs_index() + 1;
5705 while (i < last_index) {
5706 HeapRegion* curr_hr = region_at(i);
5707 assert(curr_hr->continuesHumongous(), "invariant");
5708 curr_hr->set_notHumongous();
5709 free_region(curr_hr, &hr_pre_used, free_list, par);
5710 i += 1;
5711 }
5712 assert(hr_pre_used == hr_used,
5713 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5714 "should be the same", hr_pre_used, hr_used));
5715 *pre_used += hr_pre_used;
5716 }
5717
5718 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5719 FreeRegionList* free_list,
5720 OldRegionSet* old_proxy_set,
5721 HumongousRegionSet* humongous_proxy_set,
5722 bool par) {
5723 if (pre_used > 0) {
5724 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5725 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5726 assert(_summary_bytes_used >= pre_used,
5727 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5728 "should be >= pre_used: "SIZE_FORMAT,
5729 _summary_bytes_used, pre_used));
5730 _summary_bytes_used -= pre_used;
5731 }
5732 if (free_list != NULL && !free_list->is_empty()) {
5733 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5734 _free_list.add_as_head(free_list);
5735 }
5736 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5737 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5738 _old_set.update_from_proxy(old_proxy_set);
5739 }
5740 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5741 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5742 _humongous_set.update_from_proxy(humongous_proxy_set);
5743 }
5744 }
5745
5746 class G1ParCleanupCTTask : public AbstractGangTask {
5747 CardTableModRefBS* _ct_bs;
5748 G1CollectedHeap* _g1h;
5749 HeapRegion* volatile _su_head;
5750 public:
5751 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5752 G1CollectedHeap* g1h) :
5753 AbstractGangTask("G1 Par Cleanup CT Task"),
5754 _ct_bs(ct_bs), _g1h(g1h) { }
5755
5756 void work(uint worker_id) {
5757 HeapRegion* r;
5758 while (r = _g1h->pop_dirty_cards_region()) {
5759 clear_cards(r);
5760 }
5761 }
5762
5763 void clear_cards(HeapRegion* r) {
5764 // Cards of the survivors should have already been dirtied.
5765 if (!r->is_survivor()) {
5766 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5767 }
5768 }
5769 };
5770
5771 #ifndef PRODUCT
5772 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5773 G1CollectedHeap* _g1h;
5774 CardTableModRefBS* _ct_bs;
5775 public:
5776 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5777 : _g1h(g1h), _ct_bs(ct_bs) { }
5778 virtual bool doHeapRegion(HeapRegion* r) {
5779 if (r->is_survivor()) {
5780 _g1h->verify_dirty_region(r);
5781 } else {
5782 _g1h->verify_not_dirty_region(r);
5783 }
5784 return false;
5785 }
5786 };
5787
5788 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5789 // All of the region should be clean.
5790 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5791 MemRegion mr(hr->bottom(), hr->end());
5792 ct_bs->verify_not_dirty_region(mr);
5793 }
5794
5795 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5796 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5797 // dirty allocated blocks as they allocate them. The thread that
5798 // retires each region and replaces it with a new one will do a
5799 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5800 // not dirty that area (one less thing to have to do while holding
5801 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5802 // is dirty.
5803 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5804 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5805 ct_bs->verify_dirty_region(mr);
5806 }
5807
5808 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5809 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5810 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5811 verify_dirty_region(hr);
5812 }
5813 }
5814
5815 void G1CollectedHeap::verify_dirty_young_regions() {
5816 verify_dirty_young_list(_young_list->first_region());
5817 }
5818 #endif
5819
5820 void G1CollectedHeap::cleanUpCardTable() {
5821 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5822 double start = os::elapsedTime();
5823
5824 {
5825 // Iterate over the dirty cards region list.
5826 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5827
5828 if (G1CollectedHeap::use_parallel_gc_threads()) {
5829 set_par_threads();
5830 workers()->run_task(&cleanup_task);
5831 set_par_threads(0);
5832 } else {
5833 while (_dirty_cards_region_list) {
5834 HeapRegion* r = _dirty_cards_region_list;
5835 cleanup_task.clear_cards(r);
5836 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5837 if (_dirty_cards_region_list == r) {
5838 // The last region.
5839 _dirty_cards_region_list = NULL;
5840 }
5841 r->set_next_dirty_cards_region(NULL);
5842 }
5843 }
5844 #ifndef PRODUCT
5845 if (G1VerifyCTCleanup || VerifyAfterGC) {
5846 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5847 heap_region_iterate(&cleanup_verifier);
5848 }
5849 #endif
5850 }
5851
5852 double elapsed = os::elapsedTime() - start;
5853 g1_policy()->record_clear_ct_time(elapsed * 1000.0);
5854 }
5855
5856 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5857 size_t pre_used = 0;
5858 FreeRegionList local_free_list("Local List for CSet Freeing");
5859
5860 double young_time_ms = 0.0;
5861 double non_young_time_ms = 0.0;
5862
5863 // Since the collection set is a superset of the the young list,
5864 // all we need to do to clear the young list is clear its
5865 // head and length, and unlink any young regions in the code below
5866 _young_list->clear();
5867
5868 G1CollectorPolicy* policy = g1_policy();
5869
5870 double start_sec = os::elapsedTime();
5871 bool non_young = true;
5872
5873 HeapRegion* cur = cs_head;
5874 int age_bound = -1;
5875 size_t rs_lengths = 0;
5876
5877 while (cur != NULL) {
5878 assert(!is_on_master_free_list(cur), "sanity");
5879 if (non_young) {
5880 if (cur->is_young()) {
5881 double end_sec = os::elapsedTime();
5882 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5883 non_young_time_ms += elapsed_ms;
5884
5885 start_sec = os::elapsedTime();
5886 non_young = false;
5887 }
5888 } else {
5889 if (!cur->is_young()) {
5890 double end_sec = os::elapsedTime();
5891 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5892 young_time_ms += elapsed_ms;
5893
5894 start_sec = os::elapsedTime();
5895 non_young = true;
5896 }
5897 }
5898
5899 rs_lengths += cur->rem_set()->occupied();
5900
5901 HeapRegion* next = cur->next_in_collection_set();
5902 assert(cur->in_collection_set(), "bad CS");
5903 cur->set_next_in_collection_set(NULL);
5904 cur->set_in_collection_set(false);
5905
5906 if (cur->is_young()) {
5907 int index = cur->young_index_in_cset();
5908 assert(index != -1, "invariant");
5909 assert((uint) index < policy->young_cset_region_length(), "invariant");
5910 size_t words_survived = _surviving_young_words[index];
5911 cur->record_surv_words_in_group(words_survived);
5912
5913 // At this point the we have 'popped' cur from the collection set
5914 // (linked via next_in_collection_set()) but it is still in the
5915 // young list (linked via next_young_region()). Clear the
5916 // _next_young_region field.
5917 cur->set_next_young_region(NULL);
5918 } else {
5919 int index = cur->young_index_in_cset();
5920 assert(index == -1, "invariant");
5921 }
5922
5923 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5924 (!cur->is_young() && cur->young_index_in_cset() == -1),
5925 "invariant" );
5926
5927 if (!cur->evacuation_failed()) {
5928 MemRegion used_mr = cur->used_region();
5929
5930 // And the region is empty.
5931 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5932 free_region(cur, &pre_used, &local_free_list, false /* par */);
5933 } else {
5934 cur->uninstall_surv_rate_group();
5935 if (cur->is_young()) {
5936 cur->set_young_index_in_cset(-1);
5937 }
5938 cur->set_not_young();
5939 cur->set_evacuation_failed(false);
5940 // The region is now considered to be old.
5941 _old_set.add(cur);
5942 }
5943 cur = next;
5944 }
5945
5946 policy->record_max_rs_lengths(rs_lengths);
5947 policy->cset_regions_freed();
5948
5949 double end_sec = os::elapsedTime();
5950 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5951
5952 if (non_young) {
5953 non_young_time_ms += elapsed_ms;
5954 } else {
5955 young_time_ms += elapsed_ms;
5956 }
5957
5958 update_sets_after_freeing_regions(pre_used, &local_free_list,
5959 NULL /* old_proxy_set */,
5960 NULL /* humongous_proxy_set */,
5961 false /* par */);
5962 policy->record_young_free_cset_time_ms(young_time_ms);
5963 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5964 }
5965
5966 // This routine is similar to the above but does not record
5967 // any policy statistics or update free lists; we are abandoning
5968 // the current incremental collection set in preparation of a
5969 // full collection. After the full GC we will start to build up
5970 // the incremental collection set again.
5971 // This is only called when we're doing a full collection
5972 // and is immediately followed by the tearing down of the young list.
5973
5974 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5975 HeapRegion* cur = cs_head;
5976
5977 while (cur != NULL) {
5978 HeapRegion* next = cur->next_in_collection_set();
5979 assert(cur->in_collection_set(), "bad CS");
5980 cur->set_next_in_collection_set(NULL);
5981 cur->set_in_collection_set(false);
5982 cur->set_young_index_in_cset(-1);
5983 cur = next;
5984 }
5985 }
5986
5987 void G1CollectedHeap::set_free_regions_coming() {
5988 if (G1ConcRegionFreeingVerbose) {
5989 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5990 "setting free regions coming");
5991 }
5992
5993 assert(!free_regions_coming(), "pre-condition");
5994 _free_regions_coming = true;
5995 }
5996
5997 void G1CollectedHeap::reset_free_regions_coming() {
5998 assert(free_regions_coming(), "pre-condition");
5999
6000 {
6001 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6002 _free_regions_coming = false;
6003 SecondaryFreeList_lock->notify_all();
6004 }
6005
6006 if (G1ConcRegionFreeingVerbose) {
6007 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6008 "reset free regions coming");
6009 }
6010 }
6011
6012 void G1CollectedHeap::wait_while_free_regions_coming() {
6013 // Most of the time we won't have to wait, so let's do a quick test
6014 // first before we take the lock.
6015 if (!free_regions_coming()) {
6016 return;
6017 }
6018
6019 if (G1ConcRegionFreeingVerbose) {
6020 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6021 "waiting for free regions");
6022 }
6023
6024 {
6025 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6026 while (free_regions_coming()) {
6027 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6028 }
6029 }
6030
6031 if (G1ConcRegionFreeingVerbose) {
6032 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6033 "done waiting for free regions");
6034 }
6035 }
6036
6037 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6038 assert(heap_lock_held_for_gc(),
6039 "the heap lock should already be held by or for this thread");
6040 _young_list->push_region(hr);
6041 }
6042
6043 class NoYoungRegionsClosure: public HeapRegionClosure {
6044 private:
6045 bool _success;
6046 public:
6047 NoYoungRegionsClosure() : _success(true) { }
6048 bool doHeapRegion(HeapRegion* r) {
6049 if (r->is_young()) {
6050 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6051 r->bottom(), r->end());
6052 _success = false;
6053 }
6054 return false;
6055 }
6056 bool success() { return _success; }
6057 };
6058
6059 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6060 bool ret = _young_list->check_list_empty(check_sample);
6061
6062 if (check_heap) {
6063 NoYoungRegionsClosure closure;
6064 heap_region_iterate(&closure);
6065 ret = ret && closure.success();
6066 }
6067
6068 return ret;
6069 }
6070
6071 class TearDownRegionSetsClosure : public HeapRegionClosure {
6072 private:
6073 OldRegionSet *_old_set;
6074
6075 public:
6076 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6077
6078 bool doHeapRegion(HeapRegion* r) {
6079 if (r->is_empty()) {
6080 // We ignore empty regions, we'll empty the free list afterwards
6081 } else if (r->is_young()) {
6082 // We ignore young regions, we'll empty the young list afterwards
6083 } else if (r->isHumongous()) {
6084 // We ignore humongous regions, we're not tearing down the
6085 // humongous region set
6086 } else {
6087 // The rest should be old
6088 _old_set->remove(r);
6089 }
6090 return false;
6091 }
6092
6093 ~TearDownRegionSetsClosure() {
6094 assert(_old_set->is_empty(), "post-condition");
6095 }
6096 };
6097
6098 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6099 assert_at_safepoint(true /* should_be_vm_thread */);
6100
6101 if (!free_list_only) {
6102 TearDownRegionSetsClosure cl(&_old_set);
6103 heap_region_iterate(&cl);
6104
6105 // Need to do this after the heap iteration to be able to
6106 // recognize the young regions and ignore them during the iteration.
6107 _young_list->empty_list();
6108 }
6109 _free_list.remove_all();
6110 }
6111
6112 class RebuildRegionSetsClosure : public HeapRegionClosure {
6113 private:
6114 bool _free_list_only;
6115 OldRegionSet* _old_set;
6116 FreeRegionList* _free_list;
6117 size_t _total_used;
6118
6119 public:
6120 RebuildRegionSetsClosure(bool free_list_only,
6121 OldRegionSet* old_set, FreeRegionList* free_list) :
6122 _free_list_only(free_list_only),
6123 _old_set(old_set), _free_list(free_list), _total_used(0) {
6124 assert(_free_list->is_empty(), "pre-condition");
6125 if (!free_list_only) {
6126 assert(_old_set->is_empty(), "pre-condition");
6127 }
6128 }
6129
6130 bool doHeapRegion(HeapRegion* r) {
6131 if (r->continuesHumongous()) {
6132 return false;
6133 }
6134
6135 if (r->is_empty()) {
6136 // Add free regions to the free list
6137 _free_list->add_as_tail(r);
6138 } else if (!_free_list_only) {
6139 assert(!r->is_young(), "we should not come across young regions");
6140
6141 if (r->isHumongous()) {
6142 // We ignore humongous regions, we left the humongous set unchanged
6143 } else {
6144 // The rest should be old, add them to the old set
6145 _old_set->add(r);
6146 }
6147 _total_used += r->used();
6148 }
6149
6150 return false;
6151 }
6152
6153 size_t total_used() {
6154 return _total_used;
6155 }
6156 };
6157
6158 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6159 assert_at_safepoint(true /* should_be_vm_thread */);
6160
6161 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6162 heap_region_iterate(&cl);
6163
6164 if (!free_list_only) {
6165 _summary_bytes_used = cl.total_used();
6166 }
6167 assert(_summary_bytes_used == recalculate_used(),
6168 err_msg("inconsistent _summary_bytes_used, "
6169 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6170 _summary_bytes_used, recalculate_used()));
6171 }
6172
6173 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6174 _refine_cte_cl->set_concurrent(concurrent);
6175 }
6176
6177 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6178 HeapRegion* hr = heap_region_containing(p);
6179 if (hr == NULL) {
6180 return is_in_permanent(p);
6181 } else {
6182 return hr->is_in(p);
6183 }
6184 }
6185
6186 // Methods for the mutator alloc region
6187
6188 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6189 bool force) {
6190 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6191 assert(!force || g1_policy()->can_expand_young_list(),
6192 "if force is true we should be able to expand the young list");
6193 bool young_list_full = g1_policy()->is_young_list_full();
6194 if (force || !young_list_full) {
6195 HeapRegion* new_alloc_region = new_region(word_size,
6196 false /* do_expand */);
6197 if (new_alloc_region != NULL) {
6198 set_region_short_lived_locked(new_alloc_region);
6199 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6200 return new_alloc_region;
6201 }
6202 }
6203 return NULL;
6204 }
6205
6206 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6207 size_t allocated_bytes) {
6208 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6209 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6210
6211 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6212 _summary_bytes_used += allocated_bytes;
6213 _hr_printer.retire(alloc_region);
6214 // We update the eden sizes here, when the region is retired,
6215 // instead of when it's allocated, since this is the point that its
6216 // used space has been recored in _summary_bytes_used.
6217 g1mm()->update_eden_size();
6218 }
6219
6220 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6221 bool force) {
6222 return _g1h->new_mutator_alloc_region(word_size, force);
6223 }
6224
6225 void G1CollectedHeap::set_par_threads() {
6226 // Don't change the number of workers. Use the value previously set
6227 // in the workgroup.
6228 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6229 uint n_workers = workers()->active_workers();
6230 assert(UseDynamicNumberOfGCThreads ||
6231 n_workers == workers()->total_workers(),
6232 "Otherwise should be using the total number of workers");
6233 if (n_workers == 0) {
6234 assert(false, "Should have been set in prior evacuation pause.");
6235 n_workers = ParallelGCThreads;
6236 workers()->set_active_workers(n_workers);
6237 }
6238 set_par_threads(n_workers);
6239 }
6240
6241 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6242 size_t allocated_bytes) {
6243 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6244 }
6245
6246 // Methods for the GC alloc regions
6247
6248 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6249 uint count,
6250 GCAllocPurpose ap) {
6251 assert(FreeList_lock->owned_by_self(), "pre-condition");
6252
6253 if (count < g1_policy()->max_regions(ap)) {
6254 HeapRegion* new_alloc_region = new_region(word_size,
6255 true /* do_expand */);
6256 if (new_alloc_region != NULL) {
6257 // We really only need to do this for old regions given that we
6258 // should never scan survivors. But it doesn't hurt to do it
6259 // for survivors too.
6260 new_alloc_region->set_saved_mark();
6261 if (ap == GCAllocForSurvived) {
6262 new_alloc_region->set_survivor();
6263 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6264 } else {
6265 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6266 }
6267 bool during_im = g1_policy()->during_initial_mark_pause();
6268 new_alloc_region->note_start_of_copying(during_im);
6269 return new_alloc_region;
6270 } else {
6271 g1_policy()->note_alloc_region_limit_reached(ap);
6272 }
6273 }
6274 return NULL;
6275 }
6276
6277 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6278 size_t allocated_bytes,
6279 GCAllocPurpose ap) {
6280 bool during_im = g1_policy()->during_initial_mark_pause();
6281 alloc_region->note_end_of_copying(during_im);
6282 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6283 if (ap == GCAllocForSurvived) {
6284 young_list()->add_survivor_region(alloc_region);
6285 } else {
6286 _old_set.add(alloc_region);
6287 }
6288 _hr_printer.retire(alloc_region);
6289 }
6290
6291 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6292 bool force) {
6293 assert(!force, "not supported for GC alloc regions");
6294 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6295 }
6296
6297 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6298 size_t allocated_bytes) {
6299 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6300 GCAllocForSurvived);
6301 }
6302
6303 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6304 bool force) {
6305 assert(!force, "not supported for GC alloc regions");
6306 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6307 }
6308
6309 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6310 size_t allocated_bytes) {
6311 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6312 GCAllocForTenured);
6313 }
6314 // Heap region set verification
6315
6316 class VerifyRegionListsClosure : public HeapRegionClosure {
6317 private:
6318 FreeRegionList* _free_list;
6319 OldRegionSet* _old_set;
6320 HumongousRegionSet* _humongous_set;
6321 uint _region_count;
6322
6323 public:
6324 VerifyRegionListsClosure(OldRegionSet* old_set,
6325 HumongousRegionSet* humongous_set,
6326 FreeRegionList* free_list) :
6327 _old_set(old_set), _humongous_set(humongous_set),
6328 _free_list(free_list), _region_count(0) { }
6329
6330 uint region_count() { return _region_count; }
6331
6332 bool doHeapRegion(HeapRegion* hr) {
6333 _region_count += 1;
6334
6335 if (hr->continuesHumongous()) {
6336 return false;
6337 }
6338
6339 if (hr->is_young()) {
6340 // TODO
6341 } else if (hr->startsHumongous()) {
6342 _humongous_set->verify_next_region(hr);
6343 } else if (hr->is_empty()) {
6344 _free_list->verify_next_region(hr);
6345 } else {
6346 _old_set->verify_next_region(hr);
6347 }
6348 return false;
6349 }
6350 };
6351
6352 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6353 HeapWord* bottom) {
6354 HeapWord* end = bottom + HeapRegion::GrainWords;
6355 MemRegion mr(bottom, end);
6356 assert(_g1_reserved.contains(mr), "invariant");
6357 // This might return NULL if the allocation fails
6358 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6359 }
6360
6361 void G1CollectedHeap::verify_region_sets() {
6362 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6363
6364 // First, check the explicit lists.
6365 _free_list.verify();
6366 {
6367 // Given that a concurrent operation might be adding regions to
6368 // the secondary free list we have to take the lock before
6369 // verifying it.
6370 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6371 _secondary_free_list.verify();
6372 }
6373 _old_set.verify();
6374 _humongous_set.verify();
6375
6376 // If a concurrent region freeing operation is in progress it will
6377 // be difficult to correctly attributed any free regions we come
6378 // across to the correct free list given that they might belong to
6379 // one of several (free_list, secondary_free_list, any local lists,
6380 // etc.). So, if that's the case we will skip the rest of the
6381 // verification operation. Alternatively, waiting for the concurrent
6382 // operation to complete will have a non-trivial effect on the GC's
6383 // operation (no concurrent operation will last longer than the
6384 // interval between two calls to verification) and it might hide
6385 // any issues that we would like to catch during testing.
6386 if (free_regions_coming()) {
6387 return;
6388 }
6389
6390 // Make sure we append the secondary_free_list on the free_list so
6391 // that all free regions we will come across can be safely
6392 // attributed to the free_list.
6393 append_secondary_free_list_if_not_empty_with_lock();
6394
6395 // Finally, make sure that the region accounting in the lists is
6396 // consistent with what we see in the heap.
6397 _old_set.verify_start();
6398 _humongous_set.verify_start();
6399 _free_list.verify_start();
6400
6401 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6402 heap_region_iterate(&cl);
6403
6404 _old_set.verify_end();
6405 _humongous_set.verify_end();
6406 _free_list.verify_end();
6407 }