1 /*
2 * Copyright (c) 2001, 2011, 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/g1MarkSweep.hpp"
36 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
37 #include "gc_implementation/g1/g1RemSet.inline.hpp"
38 #include "gc_implementation/g1/heapRegionRemSet.hpp"
39 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
40 #include "gc_implementation/g1/vm_operations_g1.hpp"
41 #include "gc_implementation/shared/isGCActiveMark.hpp"
42 #include "memory/gcLocker.inline.hpp"
43 #include "memory/genOopClosures.inline.hpp"
44 #include "memory/generationSpec.hpp"
45 #include "memory/referenceProcessor.hpp"
46 #include "oops/oop.inline.hpp"
47 #include "oops/oop.pcgc.inline.hpp"
48 #include "runtime/aprofiler.hpp"
49 #include "runtime/vmThread.hpp"
50
51 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
52
53 // turn it on so that the contents of the young list (scan-only /
54 // to-be-collected) are printed at "strategic" points before / during
55 // / after the collection --- this is useful for debugging
56 #define YOUNG_LIST_VERBOSE 0
57 // CURRENT STATUS
58 // This file is under construction. Search for "FIXME".
59
60 // INVARIANTS/NOTES
61 //
62 // All allocation activity covered by the G1CollectedHeap interface is
63 // serialized by acquiring the HeapLock. This happens in mem_allocate
64 // and allocate_new_tlab, which are the "entry" points to the
65 // allocation code from the rest of the JVM. (Note that this does not
66 // apply to TLAB allocation, which is not part of this interface: it
67 // is done by clients of this interface.)
68
69 // Notes on implementation of parallelism in different tasks.
70 //
71 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
72 // The number of GC workers is passed to heap_region_par_iterate_chunked().
73 // It does use run_task() which sets _n_workers in the task.
74 // G1ParTask executes g1_process_strong_roots() ->
75 // SharedHeap::process_strong_roots() which calls eventuall to
76 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
77 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
78 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
79 //
80
81 // Local to this file.
82
83 class RefineCardTableEntryClosure: public CardTableEntryClosure {
84 SuspendibleThreadSet* _sts;
85 G1RemSet* _g1rs;
86 ConcurrentG1Refine* _cg1r;
87 bool _concurrent;
88 public:
89 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
90 G1RemSet* g1rs,
91 ConcurrentG1Refine* cg1r) :
92 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
93 {}
94 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
95 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
96 // This path is executed by the concurrent refine or mutator threads,
97 // concurrently, and so we do not care if card_ptr contains references
98 // that point into the collection set.
99 assert(!oops_into_cset, "should be");
100
101 if (_concurrent && _sts->should_yield()) {
102 // Caller will actually yield.
103 return false;
104 }
105 // Otherwise, we finished successfully; return true.
106 return true;
107 }
108 void set_concurrent(bool b) { _concurrent = b; }
109 };
110
111
112 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
113 int _calls;
114 G1CollectedHeap* _g1h;
115 CardTableModRefBS* _ctbs;
116 int _histo[256];
117 public:
118 ClearLoggedCardTableEntryClosure() :
119 _calls(0)
120 {
121 _g1h = G1CollectedHeap::heap();
122 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
123 for (int i = 0; i < 256; i++) _histo[i] = 0;
124 }
125 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
126 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
127 _calls++;
128 unsigned char* ujb = (unsigned char*)card_ptr;
129 int ind = (int)(*ujb);
130 _histo[ind]++;
131 *card_ptr = -1;
132 }
133 return true;
134 }
135 int calls() { return _calls; }
136 void print_histo() {
137 gclog_or_tty->print_cr("Card table value histogram:");
138 for (int i = 0; i < 256; i++) {
139 if (_histo[i] != 0) {
140 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
141 }
142 }
143 }
144 };
145
146 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
147 int _calls;
148 G1CollectedHeap* _g1h;
149 CardTableModRefBS* _ctbs;
150 public:
151 RedirtyLoggedCardTableEntryClosure() :
152 _calls(0)
153 {
154 _g1h = G1CollectedHeap::heap();
155 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
156 }
157 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
158 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
159 _calls++;
160 *card_ptr = 0;
161 }
162 return true;
163 }
164 int calls() { return _calls; }
165 };
166
167 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
168 public:
169 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
170 *card_ptr = CardTableModRefBS::dirty_card_val();
171 return true;
172 }
173 };
174
175 YoungList::YoungList(G1CollectedHeap* g1h)
176 : _g1h(g1h), _head(NULL),
177 _length(0),
178 _last_sampled_rs_lengths(0),
179 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
180 {
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 size_t 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 %d entries, _length is %d",
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 %d",
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((size_t) young_index_in_cset == _survivor_length,
341 "post-condition");
342 _g1h->g1_policy()->note_stop_adding_survivor_regions();
343
344 _head = _survivor_head;
345 _length = _survivor_length;
346 if (_survivor_head != NULL) {
347 assert(_survivor_tail != NULL, "cause it shouldn't be");
348 assert(_survivor_length > 0, "invariant");
349 _survivor_tail->set_next_young_region(NULL);
350 }
351
352 // Don't clear the survivor list handles until the start of
353 // the next evacuation pause - we need it in order to re-tag
354 // the survivor regions from this evacuation pause as 'young'
355 // at the start of the next.
356
357 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
358
359 assert(check_list_well_formed(), "young list should be well formed");
360 }
361
362 void YoungList::print() {
363 HeapRegion* lists[] = {_head, _survivor_head};
364 const char* names[] = {"YOUNG", "SURVIVOR"};
365
366 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
367 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
368 HeapRegion *curr = lists[list];
369 if (curr == NULL)
370 gclog_or_tty->print_cr(" empty");
371 while (curr != NULL) {
372 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
373 "age: %4d, y: %d, surv: %d",
374 curr->bottom(), curr->end(),
375 curr->top(),
376 curr->prev_top_at_mark_start(),
377 curr->next_top_at_mark_start(),
378 curr->top_at_conc_mark_count(),
379 curr->age_in_surv_rate_group_cond(),
380 curr->is_young(),
381 curr->is_survivor());
382 curr = curr->get_next_young_region();
383 }
384 }
385
386 gclog_or_tty->print_cr("");
387 }
388
389 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
390 {
391 // Claim the right to put the region on the dirty cards region list
392 // by installing a self pointer.
393 HeapRegion* next = hr->get_next_dirty_cards_region();
394 if (next == NULL) {
395 HeapRegion* res = (HeapRegion*)
396 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
397 NULL);
398 if (res == NULL) {
399 HeapRegion* head;
400 do {
401 // Put the region to the dirty cards region list.
402 head = _dirty_cards_region_list;
403 next = (HeapRegion*)
404 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
405 if (next == head) {
406 assert(hr->get_next_dirty_cards_region() == hr,
407 "hr->get_next_dirty_cards_region() != hr");
408 if (next == NULL) {
409 // The last region in the list points to itself.
410 hr->set_next_dirty_cards_region(hr);
411 } else {
412 hr->set_next_dirty_cards_region(next);
413 }
414 }
415 } while (next != head);
416 }
417 }
418 }
419
420 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
421 {
422 HeapRegion* head;
423 HeapRegion* hr;
424 do {
425 head = _dirty_cards_region_list;
426 if (head == NULL) {
427 return NULL;
428 }
429 HeapRegion* new_head = head->get_next_dirty_cards_region();
430 if (head == new_head) {
431 // The last region.
432 new_head = NULL;
433 }
434 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
435 head);
436 } while (hr != head);
437 assert(hr != NULL, "invariant");
438 hr->set_next_dirty_cards_region(NULL);
439 return hr;
440 }
441
442 void G1CollectedHeap::stop_conc_gc_threads() {
443 _cg1r->stop();
444 _cmThread->stop();
445 }
446
447 #ifdef ASSERT
448 // A region is added to the collection set as it is retired
449 // so an address p can point to a region which will be in the
450 // collection set but has not yet been retired. This method
451 // therefore is only accurate during a GC pause after all
452 // regions have been retired. It is used for debugging
453 // to check if an nmethod has references to objects that can
454 // be move during a partial collection. Though it can be
455 // inaccurate, it is sufficient for G1 because the conservative
456 // implementation of is_scavengable() for G1 will indicate that
457 // all nmethods must be scanned during a partial collection.
458 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
459 HeapRegion* hr = heap_region_containing(p);
460 return hr != NULL && hr->in_collection_set();
461 }
462 #endif
463
464 // Returns true if the reference points to an object that
465 // can move in an incremental collecction.
466 bool G1CollectedHeap::is_scavengable(const void* p) {
467 G1CollectedHeap* g1h = G1CollectedHeap::heap();
468 G1CollectorPolicy* g1p = g1h->g1_policy();
469 HeapRegion* hr = heap_region_containing(p);
470 if (hr == NULL) {
471 // perm gen (or null)
472 return false;
473 } else {
474 return !hr->isHumongous();
475 }
476 }
477
478 void G1CollectedHeap::check_ct_logs_at_safepoint() {
479 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
480 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
481
482 // Count the dirty cards at the start.
483 CountNonCleanMemRegionClosure count1(this);
484 ct_bs->mod_card_iterate(&count1);
485 int orig_count = count1.n();
486
487 // First clear the logged cards.
488 ClearLoggedCardTableEntryClosure clear;
489 dcqs.set_closure(&clear);
490 dcqs.apply_closure_to_all_completed_buffers();
491 dcqs.iterate_closure_all_threads(false);
492 clear.print_histo();
493
494 // Now ensure that there's no dirty cards.
495 CountNonCleanMemRegionClosure count2(this);
496 ct_bs->mod_card_iterate(&count2);
497 if (count2.n() != 0) {
498 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
499 count2.n(), orig_count);
500 }
501 guarantee(count2.n() == 0, "Card table should be clean.");
502
503 RedirtyLoggedCardTableEntryClosure redirty;
504 JavaThread::dirty_card_queue_set().set_closure(&redirty);
505 dcqs.apply_closure_to_all_completed_buffers();
506 dcqs.iterate_closure_all_threads(false);
507 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
508 clear.calls(), orig_count);
509 guarantee(redirty.calls() == clear.calls(),
510 "Or else mechanism is broken.");
511
512 CountNonCleanMemRegionClosure count3(this);
513 ct_bs->mod_card_iterate(&count3);
514 if (count3.n() != orig_count) {
515 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
516 orig_count, count3.n());
517 guarantee(count3.n() >= orig_count, "Should have restored them all.");
518 }
519
520 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
521 }
522
523 // Private class members.
524
525 G1CollectedHeap* G1CollectedHeap::_g1h;
526
527 // Private methods.
528
529 HeapRegion*
530 G1CollectedHeap::new_region_try_secondary_free_list() {
531 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
532 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
533 if (!_secondary_free_list.is_empty()) {
534 if (G1ConcRegionFreeingVerbose) {
535 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
536 "secondary_free_list has "SIZE_FORMAT" entries",
537 _secondary_free_list.length());
538 }
539 // It looks as if there are free regions available on the
540 // secondary_free_list. Let's move them to the free_list and try
541 // again to allocate from it.
542 append_secondary_free_list();
543
544 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
545 "empty we should have moved at least one entry to the free_list");
546 HeapRegion* res = _free_list.remove_head();
547 if (G1ConcRegionFreeingVerbose) {
548 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
549 "allocated "HR_FORMAT" from secondary_free_list",
550 HR_FORMAT_PARAMS(res));
551 }
552 return res;
553 }
554
555 // Wait here until we get notifed either when (a) there are no
556 // more free regions coming or (b) some regions have been moved on
557 // the secondary_free_list.
558 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
559 }
560
561 if (G1ConcRegionFreeingVerbose) {
562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
563 "could not allocate from secondary_free_list");
564 }
565 return NULL;
566 }
567
568 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
569 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
570 "the only time we use this to allocate a humongous region is "
571 "when we are allocating a single humongous region");
572
573 HeapRegion* res;
574 if (G1StressConcRegionFreeing) {
575 if (!_secondary_free_list.is_empty()) {
576 if (G1ConcRegionFreeingVerbose) {
577 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
578 "forced to look at the secondary_free_list");
579 }
580 res = new_region_try_secondary_free_list();
581 if (res != NULL) {
582 return res;
583 }
584 }
585 }
586 res = _free_list.remove_head_or_null();
587 if (res == NULL) {
588 if (G1ConcRegionFreeingVerbose) {
589 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
590 "res == NULL, trying the secondary_free_list");
591 }
592 res = new_region_try_secondary_free_list();
593 }
594 if (res == NULL && do_expand) {
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 // Even though the heap was expanded, it might not have reached
602 // the desired size. So, we cannot assume that the allocation
603 // will succeed.
604 res = _free_list.remove_head_or_null();
605 }
606 }
607 return res;
608 }
609
610 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
611 size_t word_size) {
612 assert(isHumongous(word_size), "word_size should be humongous");
613 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
614
615 size_t first = G1_NULL_HRS_INDEX;
616 if (num_regions == 1) {
617 // Only one region to allocate, no need to go through the slower
618 // path. The caller will attempt the expasion if this fails, so
619 // let's not try to expand here too.
620 HeapRegion* hr = new_region(word_size, false /* do_expand */);
621 if (hr != NULL) {
622 first = hr->hrs_index();
623 } else {
624 first = G1_NULL_HRS_INDEX;
625 }
626 } else {
627 // We can't allocate humongous regions while cleanupComplete() is
628 // running, since some of the regions we find to be empty might not
629 // yet be added to the free list and it is not straightforward to
630 // know which list they are on so that we can remove them. Note
631 // that we only need to do this if we need to allocate more than
632 // one region to satisfy the current humongous allocation
633 // request. If we are only allocating one region we use the common
634 // region allocation code (see above).
635 wait_while_free_regions_coming();
636 append_secondary_free_list_if_not_empty_with_lock();
637
638 if (free_regions() >= num_regions) {
639 first = _hrs.find_contiguous(num_regions);
640 if (first != G1_NULL_HRS_INDEX) {
641 for (size_t i = first; i < first + num_regions; ++i) {
642 HeapRegion* hr = region_at(i);
643 assert(hr->is_empty(), "sanity");
644 assert(is_on_master_free_list(hr), "sanity");
645 hr->set_pending_removal(true);
646 }
647 _free_list.remove_all_pending(num_regions);
648 }
649 }
650 }
651 return first;
652 }
653
654 HeapWord*
655 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first,
656 size_t num_regions,
657 size_t word_size) {
658 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
659 assert(isHumongous(word_size), "word_size should be humongous");
660 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
661
662 // Index of last region in the series + 1.
663 size_t last = first + num_regions;
664
665 // We need to initialize the region(s) we just discovered. This is
666 // a bit tricky given that it can happen concurrently with
667 // refinement threads refining cards on these regions and
668 // potentially wanting to refine the BOT as they are scanning
669 // those cards (this can happen shortly after a cleanup; see CR
670 // 6991377). So we have to set up the region(s) carefully and in
671 // a specific order.
672
673 // The word size sum of all the regions we will allocate.
674 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
675 assert(word_size <= word_size_sum, "sanity");
676
677 // This will be the "starts humongous" region.
678 HeapRegion* first_hr = region_at(first);
679 // The header of the new object will be placed at the bottom of
680 // the first region.
681 HeapWord* new_obj = first_hr->bottom();
682 // This will be the new end of the first region in the series that
683 // should also match the end of the last region in the seriers.
684 HeapWord* new_end = new_obj + word_size_sum;
685 // This will be the new top of the first region that will reflect
686 // this allocation.
687 HeapWord* new_top = new_obj + word_size;
688
689 // First, we need to zero the header of the space that we will be
690 // allocating. When we update top further down, some refinement
691 // threads might try to scan the region. By zeroing the header we
692 // ensure that any thread that will try to scan the region will
693 // come across the zero klass word and bail out.
694 //
695 // NOTE: It would not have been correct to have used
696 // CollectedHeap::fill_with_object() and make the space look like
697 // an int array. The thread that is doing the allocation will
698 // later update the object header to a potentially different array
699 // type and, for a very short period of time, the klass and length
700 // fields will be inconsistent. This could cause a refinement
701 // thread to calculate the object size incorrectly.
702 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
703
704 // We will set up the first region as "starts humongous". This
705 // will also update the BOT covering all the regions to reflect
706 // that there is a single object that starts at the bottom of the
707 // first region.
708 first_hr->set_startsHumongous(new_top, new_end);
709
710 // Then, if there are any, we will set up the "continues
711 // humongous" regions.
712 HeapRegion* hr = NULL;
713 for (size_t i = first + 1; i < last; ++i) {
714 hr = region_at(i);
715 hr->set_continuesHumongous(first_hr);
716 }
717 // If we have "continues humongous" regions (hr != NULL), then the
718 // end of the last one should match new_end.
719 assert(hr == NULL || hr->end() == new_end, "sanity");
720
721 // Up to this point no concurrent thread would have been able to
722 // do any scanning on any region in this series. All the top
723 // fields still point to bottom, so the intersection between
724 // [bottom,top] and [card_start,card_end] will be empty. Before we
725 // update the top fields, we'll do a storestore to make sure that
726 // no thread sees the update to top before the zeroing of the
727 // object header and the BOT initialization.
728 OrderAccess::storestore();
729
730 // Now that the BOT and the object header have been initialized,
731 // we can update top of the "starts humongous" region.
732 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
733 "new_top should be in this region");
734 first_hr->set_top(new_top);
735 if (_hr_printer.is_active()) {
736 HeapWord* bottom = first_hr->bottom();
737 HeapWord* end = first_hr->orig_end();
738 if ((first + 1) == last) {
739 // the series has a single humongous region
740 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
741 } else {
742 // the series has more than one humongous regions
743 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
744 }
745 }
746
747 // Now, we will update the top fields of the "continues humongous"
748 // regions. The reason we need to do this is that, otherwise,
749 // these regions would look empty and this will confuse parts of
750 // G1. For example, the code that looks for a consecutive number
751 // of empty regions will consider them empty and try to
752 // re-allocate them. We can extend is_empty() to also include
753 // !continuesHumongous(), but it is easier to just update the top
754 // fields here. The way we set top for all regions (i.e., top ==
755 // end for all regions but the last one, top == new_top for the
756 // last one) is actually used when we will free up the humongous
757 // region in free_humongous_region().
758 hr = NULL;
759 for (size_t i = first + 1; i < last; ++i) {
760 hr = region_at(i);
761 if ((i + 1) == last) {
762 // last continues humongous region
763 assert(hr->bottom() < new_top && new_top <= hr->end(),
764 "new_top should fall on this region");
765 hr->set_top(new_top);
766 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
767 } else {
768 // not last one
769 assert(new_top > hr->end(), "new_top should be above this region");
770 hr->set_top(hr->end());
771 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
772 }
773 }
774 // If we have continues humongous regions (hr != NULL), then the
775 // end of the last one should match new_end and its top should
776 // match new_top.
777 assert(hr == NULL ||
778 (hr->end() == new_end && hr->top() == new_top), "sanity");
779
780 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
781 _summary_bytes_used += first_hr->used();
782 _humongous_set.add(first_hr);
783
784 return new_obj;
785 }
786
787 // If could fit into free regions w/o expansion, try.
788 // Otherwise, if can expand, do so.
789 // Otherwise, if using ex regions might help, try with ex given back.
790 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
791 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
792
793 verify_region_sets_optional();
794
795 size_t num_regions =
796 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
797 size_t x_size = expansion_regions();
798 size_t fs = _hrs.free_suffix();
799 size_t first = humongous_obj_allocate_find_first(num_regions, word_size);
800 if (first == G1_NULL_HRS_INDEX) {
801 // The only thing we can do now is attempt expansion.
802 if (fs + x_size >= num_regions) {
803 // If the number of regions we're trying to allocate for this
804 // object is at most the number of regions in the free suffix,
805 // then the call to humongous_obj_allocate_find_first() above
806 // should have succeeded and we wouldn't be here.
807 //
808 // We should only be trying to expand when the free suffix is
809 // not sufficient for the object _and_ we have some expansion
810 // room available.
811 assert(num_regions > fs, "earlier allocation should have succeeded");
812
813 ergo_verbose1(ErgoHeapSizing,
814 "attempt heap expansion",
815 ergo_format_reason("humongous allocation request failed")
816 ergo_format_byte("allocation request"),
817 word_size * HeapWordSize);
818 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
819 // Even though the heap was expanded, it might not have
820 // reached the desired size. So, we cannot assume that the
821 // allocation will succeed.
822 first = humongous_obj_allocate_find_first(num_regions, word_size);
823 }
824 }
825 }
826
827 HeapWord* result = NULL;
828 if (first != G1_NULL_HRS_INDEX) {
829 result =
830 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
831 assert(result != NULL, "it should always return a valid result");
832
833 // A successful humongous object allocation changes the used space
834 // information of the old generation so we need to recalculate the
835 // sizes and update the jstat counters here.
836 g1mm()->update_sizes();
837 }
838
839 verify_region_sets_optional();
840
841 return result;
842 }
843
844 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
845 assert_heap_not_locked_and_not_at_safepoint();
846 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
847
848 unsigned int dummy_gc_count_before;
849 return attempt_allocation(word_size, &dummy_gc_count_before);
850 }
851
852 HeapWord*
853 G1CollectedHeap::mem_allocate(size_t word_size,
854 bool* gc_overhead_limit_was_exceeded) {
855 assert_heap_not_locked_and_not_at_safepoint();
856
857 // Loop until the allocation is satisified, or unsatisfied after GC.
858 for (int try_count = 1; /* we'll return */; try_count += 1) {
859 unsigned int gc_count_before;
860
861 HeapWord* result = NULL;
862 if (!isHumongous(word_size)) {
863 result = attempt_allocation(word_size, &gc_count_before);
864 } else {
865 result = attempt_allocation_humongous(word_size, &gc_count_before);
866 }
867 if (result != NULL) {
868 return result;
869 }
870
871 // Create the garbage collection operation...
872 VM_G1CollectForAllocation op(gc_count_before, word_size);
873 // ...and get the VM thread to execute it.
874 VMThread::execute(&op);
875
876 if (op.prologue_succeeded() && op.pause_succeeded()) {
877 // If the operation was successful we'll return the result even
878 // if it is NULL. If the allocation attempt failed immediately
879 // after a Full GC, it's unlikely we'll be able to allocate now.
880 HeapWord* result = op.result();
881 if (result != NULL && !isHumongous(word_size)) {
882 // Allocations that take place on VM operations do not do any
883 // card dirtying and we have to do it here. We only have to do
884 // this for non-humongous allocations, though.
885 dirty_young_block(result, word_size);
886 }
887 return result;
888 } else {
889 assert(op.result() == NULL,
890 "the result should be NULL if the VM op did not succeed");
891 }
892
893 // Give a warning if we seem to be looping forever.
894 if ((QueuedAllocationWarningCount > 0) &&
895 (try_count % QueuedAllocationWarningCount == 0)) {
896 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
897 }
898 }
899
900 ShouldNotReachHere();
901 return NULL;
902 }
903
904 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
905 unsigned int *gc_count_before_ret) {
906 // Make sure you read the note in attempt_allocation_humongous().
907
908 assert_heap_not_locked_and_not_at_safepoint();
909 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
910 "be called for humongous allocation requests");
911
912 // We should only get here after the first-level allocation attempt
913 // (attempt_allocation()) failed to allocate.
914
915 // We will loop until a) we manage to successfully perform the
916 // allocation or b) we successfully schedule a collection which
917 // fails to perform the allocation. b) is the only case when we'll
918 // return NULL.
919 HeapWord* result = NULL;
920 for (int try_count = 1; /* we'll return */; try_count += 1) {
921 bool should_try_gc;
922 unsigned int gc_count_before;
923
924 {
925 MutexLockerEx x(Heap_lock);
926
927 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
928 false /* bot_updates */);
929 if (result != NULL) {
930 return result;
931 }
932
933 // If we reach here, attempt_allocation_locked() above failed to
934 // allocate a new region. So the mutator alloc region should be NULL.
935 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
936
937 if (GC_locker::is_active_and_needs_gc()) {
938 if (g1_policy()->can_expand_young_list()) {
939 // No need for an ergo verbose message here,
940 // can_expand_young_list() does this when it returns true.
941 result = _mutator_alloc_region.attempt_allocation_force(word_size,
942 false /* bot_updates */);
943 if (result != NULL) {
944 return result;
945 }
946 }
947 should_try_gc = false;
948 } else {
949 // Read the GC count while still holding the Heap_lock.
950 gc_count_before = SharedHeap::heap()->total_collections();
951 should_try_gc = true;
952 }
953 }
954
955 if (should_try_gc) {
956 bool succeeded;
957 result = do_collection_pause(word_size, gc_count_before, &succeeded);
958 if (result != NULL) {
959 assert(succeeded, "only way to get back a non-NULL result");
960 return result;
961 }
962
963 if (succeeded) {
964 // If we get here we successfully scheduled a collection which
965 // failed to allocate. No point in trying to allocate
966 // further. We'll just return NULL.
967 MutexLockerEx x(Heap_lock);
968 *gc_count_before_ret = SharedHeap::heap()->total_collections();
969 return NULL;
970 }
971 } else {
972 GC_locker::stall_until_clear();
973 }
974
975 // We can reach here if we were unsuccessul in scheduling a
976 // collection (because another thread beat us to it) or if we were
977 // stalled due to the GC locker. In either can we should retry the
978 // allocation attempt in case another thread successfully
979 // performed a collection and reclaimed enough space. We do the
980 // first attempt (without holding the Heap_lock) here and the
981 // follow-on attempt will be at the start of the next loop
982 // iteration (after taking the Heap_lock).
983 result = _mutator_alloc_region.attempt_allocation(word_size,
984 false /* bot_updates */);
985 if (result != NULL ){
986 return result;
987 }
988
989 // Give a warning if we seem to be looping forever.
990 if ((QueuedAllocationWarningCount > 0) &&
991 (try_count % QueuedAllocationWarningCount == 0)) {
992 warning("G1CollectedHeap::attempt_allocation_slow() "
993 "retries %d times", try_count);
994 }
995 }
996
997 ShouldNotReachHere();
998 return NULL;
999 }
1000
1001 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1002 unsigned int * gc_count_before_ret) {
1003 // The structure of this method has a lot of similarities to
1004 // attempt_allocation_slow(). The reason these two were not merged
1005 // into a single one is that such a method would require several "if
1006 // allocation is not humongous do this, otherwise do that"
1007 // conditional paths which would obscure its flow. In fact, an early
1008 // version of this code did use a unified method which was harder to
1009 // follow and, as a result, it had subtle bugs that were hard to
1010 // track down. So keeping these two methods separate allows each to
1011 // be more readable. It will be good to keep these two in sync as
1012 // much as possible.
1013
1014 assert_heap_not_locked_and_not_at_safepoint();
1015 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1016 "should only be called for humongous allocations");
1017
1018 // We will loop until a) we manage to successfully perform the
1019 // allocation or b) we successfully schedule a collection which
1020 // fails to perform the allocation. b) is the only case when we'll
1021 // return NULL.
1022 HeapWord* result = NULL;
1023 for (int try_count = 1; /* we'll return */; try_count += 1) {
1024 bool should_try_gc;
1025 unsigned int gc_count_before;
1026
1027 {
1028 MutexLockerEx x(Heap_lock);
1029
1030 // Given that humongous objects are not allocated in young
1031 // regions, we'll first try to do the allocation without doing a
1032 // collection hoping that there's enough space in the heap.
1033 result = humongous_obj_allocate(word_size);
1034 if (result != NULL) {
1035 return result;
1036 }
1037
1038 if (GC_locker::is_active_and_needs_gc()) {
1039 should_try_gc = false;
1040 } else {
1041 // Read the GC count while still holding the Heap_lock.
1042 gc_count_before = SharedHeap::heap()->total_collections();
1043 should_try_gc = true;
1044 }
1045 }
1046
1047 if (should_try_gc) {
1048 // If we failed to allocate the humongous object, we should try to
1049 // do a collection pause (if we're allowed) in case it reclaims
1050 // enough space for the allocation to succeed after the pause.
1051
1052 bool succeeded;
1053 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1054 if (result != NULL) {
1055 assert(succeeded, "only way to get back a non-NULL result");
1056 return result;
1057 }
1058
1059 if (succeeded) {
1060 // If we get here we successfully scheduled a collection which
1061 // failed to allocate. No point in trying to allocate
1062 // further. We'll just return NULL.
1063 MutexLockerEx x(Heap_lock);
1064 *gc_count_before_ret = SharedHeap::heap()->total_collections();
1065 return NULL;
1066 }
1067 } else {
1068 GC_locker::stall_until_clear();
1069 }
1070
1071 // We can reach here if we were unsuccessul in scheduling a
1072 // collection (because another thread beat us to it) or if we were
1073 // stalled due to the GC locker. In either can we should retry the
1074 // allocation attempt in case another thread successfully
1075 // performed a collection and reclaimed enough space. Give a
1076 // warning if we seem to be looping forever.
1077
1078 if ((QueuedAllocationWarningCount > 0) &&
1079 (try_count % QueuedAllocationWarningCount == 0)) {
1080 warning("G1CollectedHeap::attempt_allocation_humongous() "
1081 "retries %d times", try_count);
1082 }
1083 }
1084
1085 ShouldNotReachHere();
1086 return NULL;
1087 }
1088
1089 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1090 bool expect_null_mutator_alloc_region) {
1091 assert_at_safepoint(true /* should_be_vm_thread */);
1092 assert(_mutator_alloc_region.get() == NULL ||
1093 !expect_null_mutator_alloc_region,
1094 "the current alloc region was unexpectedly found to be non-NULL");
1095
1096 if (!isHumongous(word_size)) {
1097 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1098 false /* bot_updates */);
1099 } else {
1100 return humongous_obj_allocate(word_size);
1101 }
1102
1103 ShouldNotReachHere();
1104 }
1105
1106 class PostMCRemSetClearClosure: public HeapRegionClosure {
1107 ModRefBarrierSet* _mr_bs;
1108 public:
1109 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1110 bool doHeapRegion(HeapRegion* r) {
1111 r->reset_gc_time_stamp();
1112 if (r->continuesHumongous())
1113 return false;
1114 HeapRegionRemSet* hrrs = r->rem_set();
1115 if (hrrs != NULL) hrrs->clear();
1116 // You might think here that we could clear just the cards
1117 // corresponding to the used region. But no: if we leave a dirty card
1118 // in a region we might allocate into, then it would prevent that card
1119 // from being enqueued, and cause it to be missed.
1120 // Re: the performance cost: we shouldn't be doing full GC anyway!
1121 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1122 return false;
1123 }
1124 };
1125
1126
1127 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1128 ModRefBarrierSet* _mr_bs;
1129 public:
1130 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1131 bool doHeapRegion(HeapRegion* r) {
1132 if (r->continuesHumongous()) return false;
1133 if (r->used_region().word_size() != 0) {
1134 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1135 }
1136 return false;
1137 }
1138 };
1139
1140 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1141 G1CollectedHeap* _g1h;
1142 UpdateRSOopClosure _cl;
1143 int _worker_i;
1144 public:
1145 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1146 _cl(g1->g1_rem_set(), worker_i),
1147 _worker_i(worker_i),
1148 _g1h(g1)
1149 { }
1150
1151 bool doHeapRegion(HeapRegion* r) {
1152 if (!r->continuesHumongous()) {
1153 _cl.set_from(r);
1154 r->oop_iterate(&_cl);
1155 }
1156 return false;
1157 }
1158 };
1159
1160 class ParRebuildRSTask: public AbstractGangTask {
1161 G1CollectedHeap* _g1;
1162 public:
1163 ParRebuildRSTask(G1CollectedHeap* g1)
1164 : AbstractGangTask("ParRebuildRSTask"),
1165 _g1(g1)
1166 { }
1167
1168 void work(int i) {
1169 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1170 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1171 _g1->workers()->active_workers(),
1172 HeapRegion::RebuildRSClaimValue);
1173 }
1174 };
1175
1176 class PostCompactionPrinterClosure: public HeapRegionClosure {
1177 private:
1178 G1HRPrinter* _hr_printer;
1179 public:
1180 bool doHeapRegion(HeapRegion* hr) {
1181 assert(!hr->is_young(), "not expecting to find young regions");
1182 // We only generate output for non-empty regions.
1183 if (!hr->is_empty()) {
1184 if (!hr->isHumongous()) {
1185 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1186 } else if (hr->startsHumongous()) {
1187 if (hr->capacity() == HeapRegion::GrainBytes) {
1188 // single humongous region
1189 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1190 } else {
1191 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1192 }
1193 } else {
1194 assert(hr->continuesHumongous(), "only way to get here");
1195 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1196 }
1197 }
1198 return false;
1199 }
1200
1201 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1202 : _hr_printer(hr_printer) { }
1203 };
1204
1205 bool G1CollectedHeap::do_collection(bool explicit_gc,
1206 bool clear_all_soft_refs,
1207 size_t word_size) {
1208 assert_at_safepoint(true /* should_be_vm_thread */);
1209
1210 if (GC_locker::check_active_before_gc()) {
1211 return false;
1212 }
1213
1214 SvcGCMarker sgcm(SvcGCMarker::FULL);
1215 ResourceMark rm;
1216
1217 if (PrintHeapAtGC) {
1218 Universe::print_heap_before_gc();
1219 }
1220
1221 HRSPhaseSetter x(HRSPhaseFullGC);
1222 verify_region_sets_optional();
1223
1224 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1225 collector_policy()->should_clear_all_soft_refs();
1226
1227 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1228
1229 {
1230 IsGCActiveMark x;
1231
1232 // Timing
1233 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1234 assert(!system_gc || explicit_gc, "invariant");
1235 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1236 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1237 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1238 PrintGC, true, gclog_or_tty);
1239
1240 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1241 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1242
1243 double start = os::elapsedTime();
1244 g1_policy()->record_full_collection_start();
1245
1246 wait_while_free_regions_coming();
1247 append_secondary_free_list_if_not_empty_with_lock();
1248
1249 gc_prologue(true);
1250 increment_total_collections(true /* full gc */);
1251
1252 size_t g1h_prev_used = used();
1253 assert(used() == recalculate_used(), "Should be equal");
1254
1255 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1256 HandleMark hm; // Discard invalid handles created during verification
1257 gclog_or_tty->print(" VerifyBeforeGC:");
1258 prepare_for_verify();
1259 Universe::verify(/* allow dirty */ true,
1260 /* silent */ false,
1261 /* option */ VerifyOption_G1UsePrevMarking);
1262
1263 }
1264 pre_full_gc_dump();
1265
1266 COMPILER2_PRESENT(DerivedPointerTable::clear());
1267
1268 // Disable discovery and empty the discovered lists
1269 // for the CM ref processor.
1270 ref_processor_cm()->disable_discovery();
1271 ref_processor_cm()->abandon_partial_discovery();
1272 ref_processor_cm()->verify_no_references_recorded();
1273
1274 // Abandon current iterations of concurrent marking and concurrent
1275 // refinement, if any are in progress.
1276 concurrent_mark()->abort();
1277
1278 // Make sure we'll choose a new allocation region afterwards.
1279 release_mutator_alloc_region();
1280 abandon_gc_alloc_regions();
1281 g1_rem_set()->cleanupHRRS();
1282
1283 // We should call this after we retire any currently active alloc
1284 // regions so that all the ALLOC / RETIRE events are generated
1285 // before the start GC event.
1286 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1287
1288 // We may have added regions to the current incremental collection
1289 // set between the last GC or pause and now. We need to clear the
1290 // incremental collection set and then start rebuilding it afresh
1291 // after this full GC.
1292 abandon_collection_set(g1_policy()->inc_cset_head());
1293 g1_policy()->clear_incremental_cset();
1294 g1_policy()->stop_incremental_cset_building();
1295
1296 tear_down_region_sets(false /* free_list_only */);
1297 g1_policy()->set_full_young_gcs(true);
1298
1299 // See the comments in g1CollectedHeap.hpp and
1300 // G1CollectedHeap::ref_processing_init() about
1301 // how reference processing currently works in G1.
1302
1303 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1304 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1305
1306 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1307 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1308
1309 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1310 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1311
1312 // Do collection work
1313 {
1314 HandleMark hm; // Discard invalid handles created during gc
1315 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1316 }
1317
1318 assert(free_regions() == 0, "we should not have added any free regions");
1319 rebuild_region_sets(false /* free_list_only */);
1320
1321 // Enqueue any discovered reference objects that have
1322 // not been removed from the discovered lists.
1323 ref_processor_stw()->enqueue_discovered_references();
1324
1325 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1326
1327 MemoryService::track_memory_usage();
1328
1329 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1330 HandleMark hm; // Discard invalid handles created during verification
1331 gclog_or_tty->print(" VerifyAfterGC:");
1332 prepare_for_verify();
1333 Universe::verify(/* allow dirty */ false,
1334 /* silent */ false,
1335 /* option */ VerifyOption_G1UsePrevMarking);
1336
1337 }
1338
1339 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1340 ref_processor_stw()->verify_no_references_recorded();
1341
1342 // Note: since we've just done a full GC, concurrent
1343 // marking is no longer active. Therefore we need not
1344 // re-enable reference discovery for the CM ref processor.
1345 // That will be done at the start of the next marking cycle.
1346 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1347 ref_processor_cm()->verify_no_references_recorded();
1348
1349 reset_gc_time_stamp();
1350 // Since everything potentially moved, we will clear all remembered
1351 // sets, and clear all cards. Later we will rebuild remebered
1352 // sets. We will also reset the GC time stamps of the regions.
1353 PostMCRemSetClearClosure rs_clear(mr_bs());
1354 heap_region_iterate(&rs_clear);
1355
1356 // Resize the heap if necessary.
1357 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1358
1359 if (_hr_printer.is_active()) {
1360 // We should do this after we potentially resize the heap so
1361 // that all the COMMIT / UNCOMMIT events are generated before
1362 // the end GC event.
1363
1364 PostCompactionPrinterClosure cl(hr_printer());
1365 heap_region_iterate(&cl);
1366
1367 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1368 }
1369
1370 if (_cg1r->use_cache()) {
1371 _cg1r->clear_and_record_card_counts();
1372 _cg1r->clear_hot_cache();
1373 }
1374
1375 // Rebuild remembered sets of all regions.
1376 if (G1CollectedHeap::use_parallel_gc_threads()) {
1377 int n_workers =
1378 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1379 workers()->active_workers(),
1380 Threads::number_of_non_daemon_threads());
1381 assert(UseDynamicNumberOfGCThreads ||
1382 n_workers == workers()->total_workers(),
1383 "If not dynamic should be using all the workers");
1384 workers()->set_active_workers(n_workers);
1385 // Set parallel threads in the heap (_n_par_threads) only
1386 // before a parallel phase and always reset it to 0 after
1387 // the phase so that the number of parallel threads does
1388 // no get carried forward to a serial phase where there
1389 // may be code that is "possibly_parallel".
1390 set_par_threads(n_workers);
1391
1392 ParRebuildRSTask rebuild_rs_task(this);
1393 assert(check_heap_region_claim_values(
1394 HeapRegion::InitialClaimValue), "sanity check");
1395 assert(UseDynamicNumberOfGCThreads ||
1396 workers()->active_workers() == workers()->total_workers(),
1397 "Unless dynamic should use total workers");
1398 // Use the most recent number of active workers
1399 assert(workers()->active_workers() > 0,
1400 "Active workers not properly set");
1401 set_par_threads(workers()->active_workers());
1402 workers()->run_task(&rebuild_rs_task);
1403 set_par_threads(0);
1404 assert(check_heap_region_claim_values(
1405 HeapRegion::RebuildRSClaimValue), "sanity check");
1406 reset_heap_region_claim_values();
1407 } else {
1408 RebuildRSOutOfRegionClosure rebuild_rs(this);
1409 heap_region_iterate(&rebuild_rs);
1410 }
1411
1412 if (PrintGC) {
1413 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1414 }
1415
1416 if (true) { // FIXME
1417 // Ask the permanent generation to adjust size for full collections
1418 perm()->compute_new_size();
1419 }
1420
1421 // Start a new incremental collection set for the next pause
1422 assert(g1_policy()->collection_set() == NULL, "must be");
1423 g1_policy()->start_incremental_cset_building();
1424
1425 // Clear the _cset_fast_test bitmap in anticipation of adding
1426 // regions to the incremental collection set for the next
1427 // evacuation pause.
1428 clear_cset_fast_test();
1429
1430 init_mutator_alloc_region();
1431
1432 double end = os::elapsedTime();
1433 g1_policy()->record_full_collection_end();
1434
1435 #ifdef TRACESPINNING
1436 ParallelTaskTerminator::print_termination_counts();
1437 #endif
1438
1439 gc_epilogue(true);
1440
1441 // Discard all rset updates
1442 JavaThread::dirty_card_queue_set().abandon_logs();
1443 assert(!G1DeferredRSUpdate
1444 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1445 }
1446
1447 _young_list->reset_sampled_info();
1448 // At this point there should be no regions in the
1449 // entire heap tagged as young.
1450 assert( check_young_list_empty(true /* check_heap */),
1451 "young list should be empty at this point");
1452
1453 // Update the number of full collections that have been completed.
1454 increment_full_collections_completed(false /* concurrent */);
1455
1456 _hrs.verify_optional();
1457 verify_region_sets_optional();
1458
1459 if (PrintHeapAtGC) {
1460 Universe::print_heap_after_gc();
1461 }
1462 g1mm()->update_sizes();
1463 post_full_gc_dump();
1464
1465 return true;
1466 }
1467
1468 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1469 // do_collection() will return whether it succeeded in performing
1470 // the GC. Currently, there is no facility on the
1471 // do_full_collection() API to notify the caller than the collection
1472 // did not succeed (e.g., because it was locked out by the GC
1473 // locker). So, right now, we'll ignore the return value.
1474 bool dummy = do_collection(true, /* explicit_gc */
1475 clear_all_soft_refs,
1476 0 /* word_size */);
1477 }
1478
1479 // This code is mostly copied from TenuredGeneration.
1480 void
1481 G1CollectedHeap::
1482 resize_if_necessary_after_full_collection(size_t word_size) {
1483 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1484
1485 // Include the current allocation, if any, and bytes that will be
1486 // pre-allocated to support collections, as "used".
1487 const size_t used_after_gc = used();
1488 const size_t capacity_after_gc = capacity();
1489 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1490
1491 // This is enforced in arguments.cpp.
1492 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1493 "otherwise the code below doesn't make sense");
1494
1495 // We don't have floating point command-line arguments
1496 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1497 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1498 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1499 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1500
1501 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1502 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1503
1504 // We have to be careful here as these two calculations can overflow
1505 // 32-bit size_t's.
1506 double used_after_gc_d = (double) used_after_gc;
1507 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1508 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1509
1510 // Let's make sure that they are both under the max heap size, which
1511 // by default will make them fit into a size_t.
1512 double desired_capacity_upper_bound = (double) max_heap_size;
1513 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1514 desired_capacity_upper_bound);
1515 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1516 desired_capacity_upper_bound);
1517
1518 // We can now safely turn them into size_t's.
1519 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1520 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1521
1522 // This assert only makes sense here, before we adjust them
1523 // with respect to the min and max heap size.
1524 assert(minimum_desired_capacity <= maximum_desired_capacity,
1525 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1526 "maximum_desired_capacity = "SIZE_FORMAT,
1527 minimum_desired_capacity, maximum_desired_capacity));
1528
1529 // Should not be greater than the heap max size. No need to adjust
1530 // it with respect to the heap min size as it's a lower bound (i.e.,
1531 // we'll try to make the capacity larger than it, not smaller).
1532 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1533 // Should not be less than the heap min size. No need to adjust it
1534 // with respect to the heap max size as it's an upper bound (i.e.,
1535 // we'll try to make the capacity smaller than it, not greater).
1536 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1537
1538 if (capacity_after_gc < minimum_desired_capacity) {
1539 // Don't expand unless it's significant
1540 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1541 ergo_verbose4(ErgoHeapSizing,
1542 "attempt heap expansion",
1543 ergo_format_reason("capacity lower than "
1544 "min desired capacity after Full GC")
1545 ergo_format_byte("capacity")
1546 ergo_format_byte("occupancy")
1547 ergo_format_byte_perc("min desired capacity"),
1548 capacity_after_gc, used_after_gc,
1549 minimum_desired_capacity, (double) MinHeapFreeRatio);
1550 expand(expand_bytes);
1551
1552 // No expansion, now see if we want to shrink
1553 } else if (capacity_after_gc > maximum_desired_capacity) {
1554 // Capacity too large, compute shrinking size
1555 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1556 ergo_verbose4(ErgoHeapSizing,
1557 "attempt heap shrinking",
1558 ergo_format_reason("capacity higher than "
1559 "max desired capacity after Full GC")
1560 ergo_format_byte("capacity")
1561 ergo_format_byte("occupancy")
1562 ergo_format_byte_perc("max desired capacity"),
1563 capacity_after_gc, used_after_gc,
1564 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1565 shrink(shrink_bytes);
1566 }
1567 }
1568
1569
1570 HeapWord*
1571 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1572 bool* succeeded) {
1573 assert_at_safepoint(true /* should_be_vm_thread */);
1574
1575 *succeeded = true;
1576 // Let's attempt the allocation first.
1577 HeapWord* result =
1578 attempt_allocation_at_safepoint(word_size,
1579 false /* expect_null_mutator_alloc_region */);
1580 if (result != NULL) {
1581 assert(*succeeded, "sanity");
1582 return result;
1583 }
1584
1585 // In a G1 heap, we're supposed to keep allocation from failing by
1586 // incremental pauses. Therefore, at least for now, we'll favor
1587 // expansion over collection. (This might change in the future if we can
1588 // do something smarter than full collection to satisfy a failed alloc.)
1589 result = expand_and_allocate(word_size);
1590 if (result != NULL) {
1591 assert(*succeeded, "sanity");
1592 return result;
1593 }
1594
1595 // Expansion didn't work, we'll try to do a Full GC.
1596 bool gc_succeeded = do_collection(false, /* explicit_gc */
1597 false, /* clear_all_soft_refs */
1598 word_size);
1599 if (!gc_succeeded) {
1600 *succeeded = false;
1601 return NULL;
1602 }
1603
1604 // Retry the allocation
1605 result = attempt_allocation_at_safepoint(word_size,
1606 true /* expect_null_mutator_alloc_region */);
1607 if (result != NULL) {
1608 assert(*succeeded, "sanity");
1609 return result;
1610 }
1611
1612 // Then, try a Full GC that will collect all soft references.
1613 gc_succeeded = do_collection(false, /* explicit_gc */
1614 true, /* clear_all_soft_refs */
1615 word_size);
1616 if (!gc_succeeded) {
1617 *succeeded = false;
1618 return NULL;
1619 }
1620
1621 // Retry the allocation once more
1622 result = attempt_allocation_at_safepoint(word_size,
1623 true /* expect_null_mutator_alloc_region */);
1624 if (result != NULL) {
1625 assert(*succeeded, "sanity");
1626 return result;
1627 }
1628
1629 assert(!collector_policy()->should_clear_all_soft_refs(),
1630 "Flag should have been handled and cleared prior to this point");
1631
1632 // What else? We might try synchronous finalization later. If the total
1633 // space available is large enough for the allocation, then a more
1634 // complete compaction phase than we've tried so far might be
1635 // appropriate.
1636 assert(*succeeded, "sanity");
1637 return NULL;
1638 }
1639
1640 // Attempting to expand the heap sufficiently
1641 // to support an allocation of the given "word_size". If
1642 // successful, perform the allocation and return the address of the
1643 // allocated block, or else "NULL".
1644
1645 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1646 assert_at_safepoint(true /* should_be_vm_thread */);
1647
1648 verify_region_sets_optional();
1649
1650 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1651 ergo_verbose1(ErgoHeapSizing,
1652 "attempt heap expansion",
1653 ergo_format_reason("allocation request failed")
1654 ergo_format_byte("allocation request"),
1655 word_size * HeapWordSize);
1656 if (expand(expand_bytes)) {
1657 _hrs.verify_optional();
1658 verify_region_sets_optional();
1659 return attempt_allocation_at_safepoint(word_size,
1660 false /* expect_null_mutator_alloc_region */);
1661 }
1662 return NULL;
1663 }
1664
1665 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1666 HeapWord* new_end) {
1667 assert(old_end != new_end, "don't call this otherwise");
1668 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1669
1670 // Update the committed mem region.
1671 _g1_committed.set_end(new_end);
1672 // Tell the card table about the update.
1673 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1674 // Tell the BOT about the update.
1675 _bot_shared->resize(_g1_committed.word_size());
1676 }
1677
1678 bool G1CollectedHeap::expand(size_t expand_bytes) {
1679 size_t old_mem_size = _g1_storage.committed_size();
1680 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1681 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1682 HeapRegion::GrainBytes);
1683 ergo_verbose2(ErgoHeapSizing,
1684 "expand the heap",
1685 ergo_format_byte("requested expansion amount")
1686 ergo_format_byte("attempted expansion amount"),
1687 expand_bytes, aligned_expand_bytes);
1688
1689 // First commit the memory.
1690 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1691 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1692 if (successful) {
1693 // Then propagate this update to the necessary data structures.
1694 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1695 update_committed_space(old_end, new_end);
1696
1697 FreeRegionList expansion_list("Local Expansion List");
1698 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1699 assert(mr.start() == old_end, "post-condition");
1700 // mr might be a smaller region than what was requested if
1701 // expand_by() was unable to allocate the HeapRegion instances
1702 assert(mr.end() <= new_end, "post-condition");
1703
1704 size_t actual_expand_bytes = mr.byte_size();
1705 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1706 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1707 "post-condition");
1708 if (actual_expand_bytes < aligned_expand_bytes) {
1709 // We could not expand _hrs to the desired size. In this case we
1710 // need to shrink the committed space accordingly.
1711 assert(mr.end() < new_end, "invariant");
1712
1713 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1714 // First uncommit the memory.
1715 _g1_storage.shrink_by(diff_bytes);
1716 // Then propagate this update to the necessary data structures.
1717 update_committed_space(new_end, mr.end());
1718 }
1719 _free_list.add_as_tail(&expansion_list);
1720
1721 if (_hr_printer.is_active()) {
1722 HeapWord* curr = mr.start();
1723 while (curr < mr.end()) {
1724 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1725 _hr_printer.commit(curr, curr_end);
1726 curr = curr_end;
1727 }
1728 assert(curr == mr.end(), "post-condition");
1729 }
1730 g1_policy()->record_new_heap_size(n_regions());
1731 } else {
1732 ergo_verbose0(ErgoHeapSizing,
1733 "did not expand the heap",
1734 ergo_format_reason("heap expansion operation failed"));
1735 // The expansion of the virtual storage space was unsuccessful.
1736 // Let's see if it was because we ran out of swap.
1737 if (G1ExitOnExpansionFailure &&
1738 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1739 // We had head room...
1740 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1741 }
1742 }
1743 return successful;
1744 }
1745
1746 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1747 size_t old_mem_size = _g1_storage.committed_size();
1748 size_t aligned_shrink_bytes =
1749 ReservedSpace::page_align_size_down(shrink_bytes);
1750 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1751 HeapRegion::GrainBytes);
1752 size_t num_regions_deleted = 0;
1753 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1754 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1755 assert(mr.end() == old_end, "post-condition");
1756
1757 ergo_verbose3(ErgoHeapSizing,
1758 "shrink the heap",
1759 ergo_format_byte("requested shrinking amount")
1760 ergo_format_byte("aligned shrinking amount")
1761 ergo_format_byte("attempted shrinking amount"),
1762 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1763 if (mr.byte_size() > 0) {
1764 if (_hr_printer.is_active()) {
1765 HeapWord* curr = mr.end();
1766 while (curr > mr.start()) {
1767 HeapWord* curr_end = curr;
1768 curr -= HeapRegion::GrainWords;
1769 _hr_printer.uncommit(curr, curr_end);
1770 }
1771 assert(curr == mr.start(), "post-condition");
1772 }
1773
1774 _g1_storage.shrink_by(mr.byte_size());
1775 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1776 assert(mr.start() == new_end, "post-condition");
1777
1778 _expansion_regions += num_regions_deleted;
1779 update_committed_space(old_end, new_end);
1780 HeapRegionRemSet::shrink_heap(n_regions());
1781 g1_policy()->record_new_heap_size(n_regions());
1782 } else {
1783 ergo_verbose0(ErgoHeapSizing,
1784 "did not shrink the heap",
1785 ergo_format_reason("heap shrinking operation failed"));
1786 }
1787 }
1788
1789 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1790 verify_region_sets_optional();
1791
1792 // We should only reach here at the end of a Full GC which means we
1793 // should not not be holding to any GC alloc regions. The method
1794 // below will make sure of that and do any remaining clean up.
1795 abandon_gc_alloc_regions();
1796
1797 // Instead of tearing down / rebuilding the free lists here, we
1798 // could instead use the remove_all_pending() method on free_list to
1799 // remove only the ones that we need to remove.
1800 tear_down_region_sets(true /* free_list_only */);
1801 shrink_helper(shrink_bytes);
1802 rebuild_region_sets(true /* free_list_only */);
1803
1804 _hrs.verify_optional();
1805 verify_region_sets_optional();
1806 }
1807
1808 // Public methods.
1809
1810 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1811 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1812 #endif // _MSC_VER
1813
1814
1815 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1816 SharedHeap(policy_),
1817 _g1_policy(policy_),
1818 _dirty_card_queue_set(false),
1819 _into_cset_dirty_card_queue_set(false),
1820 _is_alive_closure_cm(this),
1821 _is_alive_closure_stw(this),
1822 _ref_processor_cm(NULL),
1823 _ref_processor_stw(NULL),
1824 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1825 _bot_shared(NULL),
1826 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1827 _evac_failure_scan_stack(NULL) ,
1828 _mark_in_progress(false),
1829 _cg1r(NULL), _summary_bytes_used(0),
1830 _g1mm(NULL),
1831 _refine_cte_cl(NULL),
1832 _full_collection(false),
1833 _free_list("Master Free List"),
1834 _secondary_free_list("Secondary Free List"),
1835 _old_set("Old Set"),
1836 _humongous_set("Master Humongous Set"),
1837 _free_regions_coming(false),
1838 _young_list(new YoungList(this)),
1839 _gc_time_stamp(0),
1840 _retained_old_gc_alloc_region(NULL),
1841 _surviving_young_words(NULL),
1842 _full_collections_completed(0),
1843 _in_cset_fast_test(NULL),
1844 _in_cset_fast_test_base(NULL),
1845 _dirty_cards_region_list(NULL),
1846 _worker_cset_start_region(NULL),
1847 _worker_cset_start_region_time_stamp(NULL) {
1848 _g1h = this; // To catch bugs.
1849 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1850 vm_exit_during_initialization("Failed necessary allocation.");
1851 }
1852
1853 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1854
1855 int n_queues = MAX2((int)ParallelGCThreads, 1);
1856 _task_queues = new RefToScanQueueSet(n_queues);
1857
1858 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1859 assert(n_rem_sets > 0, "Invariant.");
1860
1861 HeapRegionRemSetIterator** iter_arr =
1862 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1863 for (int i = 0; i < n_queues; i++) {
1864 iter_arr[i] = new HeapRegionRemSetIterator();
1865 }
1866 _rem_set_iterator = iter_arr;
1867
1868 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues);
1869 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues);
1870
1871 for (int i = 0; i < n_queues; i++) {
1872 RefToScanQueue* q = new RefToScanQueue();
1873 q->initialize();
1874 _task_queues->register_queue(i, q);
1875 }
1876
1877 clear_cset_start_regions();
1878
1879 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1880 }
1881
1882 jint G1CollectedHeap::initialize() {
1883 CollectedHeap::pre_initialize();
1884 os::enable_vtime();
1885
1886 // Necessary to satisfy locking discipline assertions.
1887
1888 MutexLocker x(Heap_lock);
1889
1890 // We have to initialize the printer before committing the heap, as
1891 // it will be used then.
1892 _hr_printer.set_active(G1PrintHeapRegions);
1893
1894 // While there are no constraints in the GC code that HeapWordSize
1895 // be any particular value, there are multiple other areas in the
1896 // system which believe this to be true (e.g. oop->object_size in some
1897 // cases incorrectly returns the size in wordSize units rather than
1898 // HeapWordSize).
1899 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1900
1901 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1902 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1903
1904 // Ensure that the sizes are properly aligned.
1905 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1906 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1907
1908 _cg1r = new ConcurrentG1Refine();
1909
1910 // Reserve the maximum.
1911 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1912 // Includes the perm-gen.
1913
1914 // When compressed oops are enabled, the preferred heap base
1915 // is calculated by subtracting the requested size from the
1916 // 32Gb boundary and using the result as the base address for
1917 // heap reservation. If the requested size is not aligned to
1918 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1919 // into the ReservedHeapSpace constructor) then the actual
1920 // base of the reserved heap may end up differing from the
1921 // address that was requested (i.e. the preferred heap base).
1922 // If this happens then we could end up using a non-optimal
1923 // compressed oops mode.
1924
1925 // Since max_byte_size is aligned to the size of a heap region (checked
1926 // above), we also need to align the perm gen size as it might not be.
1927 const size_t total_reserved = max_byte_size +
1928 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1929 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1930
1931 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1932
1933 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1934 UseLargePages, addr);
1935
1936 if (UseCompressedOops) {
1937 if (addr != NULL && !heap_rs.is_reserved()) {
1938 // Failed to reserve at specified address - the requested memory
1939 // region is taken already, for example, by 'java' launcher.
1940 // Try again to reserver heap higher.
1941 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1942
1943 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1944 UseLargePages, addr);
1945
1946 if (addr != NULL && !heap_rs0.is_reserved()) {
1947 // Failed to reserve at specified address again - give up.
1948 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1949 assert(addr == NULL, "");
1950
1951 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1952 UseLargePages, addr);
1953 heap_rs = heap_rs1;
1954 } else {
1955 heap_rs = heap_rs0;
1956 }
1957 }
1958 }
1959
1960 if (!heap_rs.is_reserved()) {
1961 vm_exit_during_initialization("Could not reserve enough space for object heap");
1962 return JNI_ENOMEM;
1963 }
1964
1965 // It is important to do this in a way such that concurrent readers can't
1966 // temporarily think somethings in the heap. (I've actually seen this
1967 // happen in asserts: DLD.)
1968 _reserved.set_word_size(0);
1969 _reserved.set_start((HeapWord*)heap_rs.base());
1970 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1971
1972 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1973
1974 // Create the gen rem set (and barrier set) for the entire reserved region.
1975 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1976 set_barrier_set(rem_set()->bs());
1977 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1978 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1979 } else {
1980 vm_exit_during_initialization("G1 requires a mod ref bs.");
1981 return JNI_ENOMEM;
1982 }
1983
1984 // Also create a G1 rem set.
1985 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1986 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1987 } else {
1988 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1989 return JNI_ENOMEM;
1990 }
1991
1992 // Carve out the G1 part of the heap.
1993
1994 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1995 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1996 g1_rs.size()/HeapWordSize);
1997 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1998
1999 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2000
2001 _g1_storage.initialize(g1_rs, 0);
2002 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2003 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2004 (HeapWord*) _g1_reserved.end(),
2005 _expansion_regions);
2006
2007 // 6843694 - ensure that the maximum region index can fit
2008 // in the remembered set structures.
2009 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2010 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2011
2012 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2013 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2014 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2015 "too many cards per region");
2016
2017 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2018
2019 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2020 heap_word_size(init_byte_size));
2021
2022 _g1h = this;
2023
2024 _in_cset_fast_test_length = max_regions();
2025 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2026
2027 // We're biasing _in_cset_fast_test to avoid subtracting the
2028 // beginning of the heap every time we want to index; basically
2029 // it's the same with what we do with the card table.
2030 _in_cset_fast_test = _in_cset_fast_test_base -
2031 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2032
2033 // Clear the _cset_fast_test bitmap in anticipation of adding
2034 // regions to the incremental collection set for the first
2035 // evacuation pause.
2036 clear_cset_fast_test();
2037
2038 // Create the ConcurrentMark data structure and thread.
2039 // (Must do this late, so that "max_regions" is defined.)
2040 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
2041 _cmThread = _cm->cmThread();
2042
2043 // Initialize the from_card cache structure of HeapRegionRemSet.
2044 HeapRegionRemSet::init_heap(max_regions());
2045
2046 // Now expand into the initial heap size.
2047 if (!expand(init_byte_size)) {
2048 vm_exit_during_initialization("Failed to allocate initial heap.");
2049 return JNI_ENOMEM;
2050 }
2051
2052 // Perform any initialization actions delegated to the policy.
2053 g1_policy()->init();
2054
2055 _refine_cte_cl =
2056 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2057 g1_rem_set(),
2058 concurrent_g1_refine());
2059 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2060
2061 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2062 SATB_Q_FL_lock,
2063 G1SATBProcessCompletedThreshold,
2064 Shared_SATB_Q_lock);
2065
2066 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2067 DirtyCardQ_FL_lock,
2068 concurrent_g1_refine()->yellow_zone(),
2069 concurrent_g1_refine()->red_zone(),
2070 Shared_DirtyCardQ_lock);
2071
2072 if (G1DeferredRSUpdate) {
2073 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2074 DirtyCardQ_FL_lock,
2075 -1, // never trigger processing
2076 -1, // no limit on length
2077 Shared_DirtyCardQ_lock,
2078 &JavaThread::dirty_card_queue_set());
2079 }
2080
2081 // Initialize the card queue set used to hold cards containing
2082 // references into the collection set.
2083 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2084 DirtyCardQ_FL_lock,
2085 -1, // never trigger processing
2086 -1, // no limit on length
2087 Shared_DirtyCardQ_lock,
2088 &JavaThread::dirty_card_queue_set());
2089
2090 // In case we're keeping closure specialization stats, initialize those
2091 // counts and that mechanism.
2092 SpecializationStats::clear();
2093
2094 // Do later initialization work for concurrent refinement.
2095 _cg1r->init();
2096
2097 // Here we allocate the dummy full region that is required by the
2098 // G1AllocRegion class. If we don't pass an address in the reserved
2099 // space here, lots of asserts fire.
2100
2101 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2102 _g1_reserved.start());
2103 // We'll re-use the same region whether the alloc region will
2104 // require BOT updates or not and, if it doesn't, then a non-young
2105 // region will complain that it cannot support allocations without
2106 // BOT updates. So we'll tag the dummy region as young to avoid that.
2107 dummy_region->set_young();
2108 // Make sure it's full.
2109 dummy_region->set_top(dummy_region->end());
2110 G1AllocRegion::setup(this, dummy_region);
2111
2112 init_mutator_alloc_region();
2113
2114 // Do create of the monitoring and management support so that
2115 // values in the heap have been properly initialized.
2116 _g1mm = new G1MonitoringSupport(this);
2117
2118 return JNI_OK;
2119 }
2120
2121 void G1CollectedHeap::ref_processing_init() {
2122 // Reference processing in G1 currently works as follows:
2123 //
2124 // * There are two reference processor instances. One is
2125 // used to record and process discovered references
2126 // during concurrent marking; the other is used to
2127 // record and process references during STW pauses
2128 // (both full and incremental).
2129 // * Both ref processors need to 'span' the entire heap as
2130 // the regions in the collection set may be dotted around.
2131 //
2132 // * For the concurrent marking ref processor:
2133 // * Reference discovery is enabled at initial marking.
2134 // * Reference discovery is disabled and the discovered
2135 // references processed etc during remarking.
2136 // * Reference discovery is MT (see below).
2137 // * Reference discovery requires a barrier (see below).
2138 // * Reference processing may or may not be MT
2139 // (depending on the value of ParallelRefProcEnabled
2140 // and ParallelGCThreads).
2141 // * A full GC disables reference discovery by the CM
2142 // ref processor and abandons any entries on it's
2143 // discovered lists.
2144 //
2145 // * For the STW processor:
2146 // * Non MT discovery is enabled at the start of a full GC.
2147 // * Processing and enqueueing during a full GC is non-MT.
2148 // * During a full GC, references are processed after marking.
2149 //
2150 // * Discovery (may or may not be MT) is enabled at the start
2151 // of an incremental evacuation pause.
2152 // * References are processed near the end of a STW evacuation pause.
2153 // * For both types of GC:
2154 // * Discovery is atomic - i.e. not concurrent.
2155 // * Reference discovery will not need a barrier.
2156
2157 SharedHeap::ref_processing_init();
2158 MemRegion mr = reserved_region();
2159
2160 // Concurrent Mark ref processor
2161 _ref_processor_cm =
2162 new ReferenceProcessor(mr, // span
2163 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2164 // mt processing
2165 (int) ParallelGCThreads,
2166 // degree of mt processing
2167 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2168 // mt discovery
2169 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2170 // degree of mt discovery
2171 false,
2172 // Reference discovery is not atomic
2173 &_is_alive_closure_cm,
2174 // is alive closure
2175 // (for efficiency/performance)
2176 true);
2177 // Setting next fields of discovered
2178 // lists requires a barrier.
2179
2180 // STW ref processor
2181 _ref_processor_stw =
2182 new ReferenceProcessor(mr, // span
2183 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2184 // mt processing
2185 MAX2((int)ParallelGCThreads, 1),
2186 // degree of mt processing
2187 (ParallelGCThreads > 1),
2188 // mt discovery
2189 MAX2((int)ParallelGCThreads, 1),
2190 // degree of mt discovery
2191 true,
2192 // Reference discovery is atomic
2193 &_is_alive_closure_stw,
2194 // is alive closure
2195 // (for efficiency/performance)
2196 false);
2197 // Setting next fields of discovered
2198 // lists requires a barrier.
2199 }
2200
2201 size_t G1CollectedHeap::capacity() const {
2202 return _g1_committed.byte_size();
2203 }
2204
2205 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2206 DirtyCardQueue* into_cset_dcq,
2207 bool concurrent,
2208 int worker_i) {
2209 // Clean cards in the hot card cache
2210 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2211
2212 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2213 int n_completed_buffers = 0;
2214 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2215 n_completed_buffers++;
2216 }
2217 g1_policy()->record_update_rs_processed_buffers(worker_i,
2218 (double) n_completed_buffers);
2219 dcqs.clear_n_completed_buffers();
2220 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2221 }
2222
2223
2224 // Computes the sum of the storage used by the various regions.
2225
2226 size_t G1CollectedHeap::used() const {
2227 assert(Heap_lock->owner() != NULL,
2228 "Should be owned on this thread's behalf.");
2229 size_t result = _summary_bytes_used;
2230 // Read only once in case it is set to NULL concurrently
2231 HeapRegion* hr = _mutator_alloc_region.get();
2232 if (hr != NULL)
2233 result += hr->used();
2234 return result;
2235 }
2236
2237 size_t G1CollectedHeap::used_unlocked() const {
2238 size_t result = _summary_bytes_used;
2239 return result;
2240 }
2241
2242 class SumUsedClosure: public HeapRegionClosure {
2243 size_t _used;
2244 public:
2245 SumUsedClosure() : _used(0) {}
2246 bool doHeapRegion(HeapRegion* r) {
2247 if (!r->continuesHumongous()) {
2248 _used += r->used();
2249 }
2250 return false;
2251 }
2252 size_t result() { return _used; }
2253 };
2254
2255 size_t G1CollectedHeap::recalculate_used() const {
2256 SumUsedClosure blk;
2257 heap_region_iterate(&blk);
2258 return blk.result();
2259 }
2260
2261 size_t G1CollectedHeap::unsafe_max_alloc() {
2262 if (free_regions() > 0) return HeapRegion::GrainBytes;
2263 // otherwise, is there space in the current allocation region?
2264
2265 // We need to store the current allocation region in a local variable
2266 // here. The problem is that this method doesn't take any locks and
2267 // there may be other threads which overwrite the current allocation
2268 // region field. attempt_allocation(), for example, sets it to NULL
2269 // and this can happen *after* the NULL check here but before the call
2270 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2271 // to be a problem in the optimized build, since the two loads of the
2272 // current allocation region field are optimized away.
2273 HeapRegion* hr = _mutator_alloc_region.get();
2274 if (hr == NULL) {
2275 return 0;
2276 }
2277 return hr->free();
2278 }
2279
2280 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2281 return
2282 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2283 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2284 }
2285
2286 #ifndef PRODUCT
2287 void G1CollectedHeap::allocate_dummy_regions() {
2288 // Let's fill up most of the region
2289 size_t word_size = HeapRegion::GrainWords - 1024;
2290 // And as a result the region we'll allocate will be humongous.
2291 guarantee(isHumongous(word_size), "sanity");
2292
2293 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2294 // Let's use the existing mechanism for the allocation
2295 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2296 if (dummy_obj != NULL) {
2297 MemRegion mr(dummy_obj, word_size);
2298 CollectedHeap::fill_with_object(mr);
2299 } else {
2300 // If we can't allocate once, we probably cannot allocate
2301 // again. Let's get out of the loop.
2302 break;
2303 }
2304 }
2305 }
2306 #endif // !PRODUCT
2307
2308 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2309 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2310
2311 // We assume that if concurrent == true, then the caller is a
2312 // concurrent thread that was joined the Suspendible Thread
2313 // Set. If there's ever a cheap way to check this, we should add an
2314 // assert here.
2315
2316 // We have already incremented _total_full_collections at the start
2317 // of the GC, so total_full_collections() represents how many full
2318 // collections have been started.
2319 unsigned int full_collections_started = total_full_collections();
2320
2321 // Given that this method is called at the end of a Full GC or of a
2322 // concurrent cycle, and those can be nested (i.e., a Full GC can
2323 // interrupt a concurrent cycle), the number of full collections
2324 // completed should be either one (in the case where there was no
2325 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2326 // behind the number of full collections started.
2327
2328 // This is the case for the inner caller, i.e. a Full GC.
2329 assert(concurrent ||
2330 (full_collections_started == _full_collections_completed + 1) ||
2331 (full_collections_started == _full_collections_completed + 2),
2332 err_msg("for inner caller (Full GC): full_collections_started = %u "
2333 "is inconsistent with _full_collections_completed = %u",
2334 full_collections_started, _full_collections_completed));
2335
2336 // This is the case for the outer caller, i.e. the concurrent cycle.
2337 assert(!concurrent ||
2338 (full_collections_started == _full_collections_completed + 1),
2339 err_msg("for outer caller (concurrent cycle): "
2340 "full_collections_started = %u "
2341 "is inconsistent with _full_collections_completed = %u",
2342 full_collections_started, _full_collections_completed));
2343
2344 _full_collections_completed += 1;
2345
2346 // We need to clear the "in_progress" flag in the CM thread before
2347 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2348 // is set) so that if a waiter requests another System.gc() it doesn't
2349 // incorrectly see that a marking cyle is still in progress.
2350 if (concurrent) {
2351 _cmThread->clear_in_progress();
2352 }
2353
2354 // This notify_all() will ensure that a thread that called
2355 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2356 // and it's waiting for a full GC to finish will be woken up. It is
2357 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2358 FullGCCount_lock->notify_all();
2359 }
2360
2361 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2362 assert_at_safepoint(true /* should_be_vm_thread */);
2363 GCCauseSetter gcs(this, cause);
2364 switch (cause) {
2365 case GCCause::_heap_inspection:
2366 case GCCause::_heap_dump: {
2367 HandleMark hm;
2368 do_full_collection(false); // don't clear all soft refs
2369 break;
2370 }
2371 default: // XXX FIX ME
2372 ShouldNotReachHere(); // Unexpected use of this function
2373 }
2374 }
2375
2376 void G1CollectedHeap::collect(GCCause::Cause cause) {
2377 // The caller doesn't have the Heap_lock
2378 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2379
2380 unsigned int gc_count_before;
2381 unsigned int full_gc_count_before;
2382 {
2383 MutexLocker ml(Heap_lock);
2384
2385 // Read the GC count while holding the Heap_lock
2386 gc_count_before = SharedHeap::heap()->total_collections();
2387 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2388 }
2389
2390 if (should_do_concurrent_full_gc(cause)) {
2391 // Schedule an initial-mark evacuation pause that will start a
2392 // concurrent cycle. We're setting word_size to 0 which means that
2393 // we are not requesting a post-GC allocation.
2394 VM_G1IncCollectionPause op(gc_count_before,
2395 0, /* word_size */
2396 true, /* should_initiate_conc_mark */
2397 g1_policy()->max_pause_time_ms(),
2398 cause);
2399 VMThread::execute(&op);
2400 } else {
2401 if (cause == GCCause::_gc_locker
2402 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2403
2404 // Schedule a standard evacuation pause. We're setting word_size
2405 // to 0 which means that we are not requesting a post-GC allocation.
2406 VM_G1IncCollectionPause op(gc_count_before,
2407 0, /* word_size */
2408 false, /* should_initiate_conc_mark */
2409 g1_policy()->max_pause_time_ms(),
2410 cause);
2411 VMThread::execute(&op);
2412 } else {
2413 // Schedule a Full GC.
2414 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2415 VMThread::execute(&op);
2416 }
2417 }
2418 }
2419
2420 bool G1CollectedHeap::is_in(const void* p) const {
2421 HeapRegion* hr = _hrs.addr_to_region((HeapWord*) p);
2422 if (hr != NULL) {
2423 return hr->is_in(p);
2424 } else {
2425 return _perm_gen->as_gen()->is_in(p);
2426 }
2427 }
2428
2429 // Iteration functions.
2430
2431 // Iterates an OopClosure over all ref-containing fields of objects
2432 // within a HeapRegion.
2433
2434 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2435 MemRegion _mr;
2436 OopClosure* _cl;
2437 public:
2438 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2439 : _mr(mr), _cl(cl) {}
2440 bool doHeapRegion(HeapRegion* r) {
2441 if (! r->continuesHumongous()) {
2442 r->oop_iterate(_cl);
2443 }
2444 return false;
2445 }
2446 };
2447
2448 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2449 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2450 heap_region_iterate(&blk);
2451 if (do_perm) {
2452 perm_gen()->oop_iterate(cl);
2453 }
2454 }
2455
2456 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2457 IterateOopClosureRegionClosure blk(mr, cl);
2458 heap_region_iterate(&blk);
2459 if (do_perm) {
2460 perm_gen()->oop_iterate(cl);
2461 }
2462 }
2463
2464 // Iterates an ObjectClosure over all objects within a HeapRegion.
2465
2466 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2467 ObjectClosure* _cl;
2468 public:
2469 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2470 bool doHeapRegion(HeapRegion* r) {
2471 if (! r->continuesHumongous()) {
2472 r->object_iterate(_cl);
2473 }
2474 return false;
2475 }
2476 };
2477
2478 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2479 IterateObjectClosureRegionClosure blk(cl);
2480 heap_region_iterate(&blk);
2481 if (do_perm) {
2482 perm_gen()->object_iterate(cl);
2483 }
2484 }
2485
2486 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2487 // FIXME: is this right?
2488 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2489 }
2490
2491 // Calls a SpaceClosure on a HeapRegion.
2492
2493 class SpaceClosureRegionClosure: public HeapRegionClosure {
2494 SpaceClosure* _cl;
2495 public:
2496 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2497 bool doHeapRegion(HeapRegion* r) {
2498 _cl->do_space(r);
2499 return false;
2500 }
2501 };
2502
2503 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2504 SpaceClosureRegionClosure blk(cl);
2505 heap_region_iterate(&blk);
2506 }
2507
2508 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2509 _hrs.iterate(cl);
2510 }
2511
2512 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2513 HeapRegionClosure* cl) const {
2514 _hrs.iterate_from(r, cl);
2515 }
2516
2517 void
2518 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2519 int worker,
2520 int no_of_par_workers,
2521 jint claim_value) {
2522 const size_t regions = n_regions();
2523 const size_t max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2524 no_of_par_workers :
2525 1);
2526 assert(UseDynamicNumberOfGCThreads ||
2527 no_of_par_workers == workers()->total_workers(),
2528 "Non dynamic should use fixed number of workers");
2529 // try to spread out the starting points of the workers
2530 const size_t start_index = regions / max_workers * (size_t) worker;
2531
2532 // each worker will actually look at all regions
2533 for (size_t count = 0; count < regions; ++count) {
2534 const size_t index = (start_index + count) % regions;
2535 assert(0 <= index && index < regions, "sanity");
2536 HeapRegion* r = region_at(index);
2537 // we'll ignore "continues humongous" regions (we'll process them
2538 // when we come across their corresponding "start humongous"
2539 // region) and regions already claimed
2540 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2541 continue;
2542 }
2543 // OK, try to claim it
2544 if (r->claimHeapRegion(claim_value)) {
2545 // success!
2546 assert(!r->continuesHumongous(), "sanity");
2547 if (r->startsHumongous()) {
2548 // If the region is "starts humongous" we'll iterate over its
2549 // "continues humongous" first; in fact we'll do them
2550 // first. The order is important. In on case, calling the
2551 // closure on the "starts humongous" region might de-allocate
2552 // and clear all its "continues humongous" regions and, as a
2553 // result, we might end up processing them twice. So, we'll do
2554 // them first (notice: most closures will ignore them anyway) and
2555 // then we'll do the "starts humongous" region.
2556 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2557 HeapRegion* chr = region_at(ch_index);
2558
2559 // if the region has already been claimed or it's not
2560 // "continues humongous" we're done
2561 if (chr->claim_value() == claim_value ||
2562 !chr->continuesHumongous()) {
2563 break;
2564 }
2565
2566 // Noone should have claimed it directly. We can given
2567 // that we claimed its "starts humongous" region.
2568 assert(chr->claim_value() != claim_value, "sanity");
2569 assert(chr->humongous_start_region() == r, "sanity");
2570
2571 if (chr->claimHeapRegion(claim_value)) {
2572 // we should always be able to claim it; noone else should
2573 // be trying to claim this region
2574
2575 bool res2 = cl->doHeapRegion(chr);
2576 assert(!res2, "Should not abort");
2577
2578 // Right now, this holds (i.e., no closure that actually
2579 // does something with "continues humongous" regions
2580 // clears them). We might have to weaken it in the future,
2581 // but let's leave these two asserts here for extra safety.
2582 assert(chr->continuesHumongous(), "should still be the case");
2583 assert(chr->humongous_start_region() == r, "sanity");
2584 } else {
2585 guarantee(false, "we should not reach here");
2586 }
2587 }
2588 }
2589
2590 assert(!r->continuesHumongous(), "sanity");
2591 bool res = cl->doHeapRegion(r);
2592 assert(!res, "Should not abort");
2593 }
2594 }
2595 }
2596
2597 class ResetClaimValuesClosure: public HeapRegionClosure {
2598 public:
2599 bool doHeapRegion(HeapRegion* r) {
2600 r->set_claim_value(HeapRegion::InitialClaimValue);
2601 return false;
2602 }
2603 };
2604
2605 void
2606 G1CollectedHeap::reset_heap_region_claim_values() {
2607 ResetClaimValuesClosure blk;
2608 heap_region_iterate(&blk);
2609 }
2610
2611 #ifdef ASSERT
2612 // This checks whether all regions in the heap have the correct claim
2613 // value. I also piggy-backed on this a check to ensure that the
2614 // humongous_start_region() information on "continues humongous"
2615 // regions is correct.
2616
2617 class CheckClaimValuesClosure : public HeapRegionClosure {
2618 private:
2619 jint _claim_value;
2620 size_t _failures;
2621 HeapRegion* _sh_region;
2622 public:
2623 CheckClaimValuesClosure(jint claim_value) :
2624 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2625 bool doHeapRegion(HeapRegion* r) {
2626 if (r->claim_value() != _claim_value) {
2627 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2628 "claim value = %d, should be %d",
2629 HR_FORMAT_PARAMS(r),
2630 r->claim_value(), _claim_value);
2631 ++_failures;
2632 }
2633 if (!r->isHumongous()) {
2634 _sh_region = NULL;
2635 } else if (r->startsHumongous()) {
2636 _sh_region = r;
2637 } else if (r->continuesHumongous()) {
2638 if (r->humongous_start_region() != _sh_region) {
2639 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2640 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2641 HR_FORMAT_PARAMS(r),
2642 r->humongous_start_region(),
2643 _sh_region);
2644 ++_failures;
2645 }
2646 }
2647 return false;
2648 }
2649 size_t failures() {
2650 return _failures;
2651 }
2652 };
2653
2654 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2655 CheckClaimValuesClosure cl(claim_value);
2656 heap_region_iterate(&cl);
2657 return cl.failures() == 0;
2658 }
2659
2660 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2661 jint _claim_value;
2662 size_t _failures;
2663
2664 public:
2665 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2666 _claim_value(claim_value),
2667 _failures(0) { }
2668
2669 size_t failures() {
2670 return _failures;
2671 }
2672
2673 bool doHeapRegion(HeapRegion* hr) {
2674 assert(hr->in_collection_set(), "how?");
2675 assert(!hr->isHumongous(), "H-region in CSet");
2676 if (hr->claim_value() != _claim_value) {
2677 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2678 "claim value = %d, should be %d",
2679 HR_FORMAT_PARAMS(hr),
2680 hr->claim_value(), _claim_value);
2681 _failures += 1;
2682 }
2683 return false;
2684 }
2685 };
2686
2687 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2688 CheckClaimValuesInCSetHRClosure cl(claim_value);
2689 collection_set_iterate(&cl);
2690 return cl.failures() == 0;
2691 }
2692 #endif // ASSERT
2693
2694 // Clear the cached CSet starting regions and (more importantly)
2695 // the time stamps. Called when we reset the GC time stamp.
2696 void G1CollectedHeap::clear_cset_start_regions() {
2697 assert(_worker_cset_start_region != NULL, "sanity");
2698 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2699
2700 int n_queues = MAX2((int)ParallelGCThreads, 1);
2701 for (int i = 0; i < n_queues; i++) {
2702 _worker_cset_start_region[i] = NULL;
2703 _worker_cset_start_region_time_stamp[i] = 0;
2704 }
2705 }
2706
2707 // Given the id of a worker, obtain or calculate a suitable
2708 // starting region for iterating over the current collection set.
2709 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2710 assert(_worker_cset_start_region != NULL, "sanity");
2711 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2712 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2713
2714 HeapRegion* result = NULL;
2715 unsigned gc_time_stamp = get_gc_time_stamp();
2716
2717 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2718 // Cached starting region for current worker was set
2719 // during the current pause - so it's valid.
2720 // Note: the cached starting heap region may be NULL
2721 // (when the collection set is empty).
2722 result = _worker_cset_start_region[worker_i];
2723 assert(result == NULL || result->in_collection_set(), "sanity");
2724 return result;
2725 }
2726
2727 // The cached entry was not valid so let's calculate
2728 // a suitable starting heap region for this worker.
2729
2730 // We want the parallel threads to start their collection
2731 // set iteration at different collection set regions to
2732 // avoid contention.
2733 // If we have:
2734 // n collection set regions
2735 // p threads
2736 // Then thread t will start at region floor ((t * n) / p)
2737
2738 result = g1_policy()->collection_set();
2739 if (G1CollectedHeap::use_parallel_gc_threads()) {
2740 size_t cs_size = g1_policy()->cset_region_length();
2741 int active_workers = workers()->active_workers();
2742 assert(UseDynamicNumberOfGCThreads ||
2743 active_workers == workers()->total_workers(),
2744 "Unless dynamic should use total workers");
2745
2746 size_t end_ind = (cs_size * worker_i) / active_workers;
2747 size_t start_ind = 0;
2748
2749 if (worker_i > 0 &&
2750 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2751 // Previous workers starting region is valid
2752 // so let's iterate from there
2753 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2754 result = _worker_cset_start_region[worker_i - 1];
2755 }
2756
2757 for (size_t i = start_ind; i < end_ind; i++) {
2758 result = result->next_in_collection_set();
2759 }
2760 }
2761
2762 // Note: the calculated starting heap region may be NULL
2763 // (when the collection set is empty).
2764 assert(result == NULL || result->in_collection_set(), "sanity");
2765 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2766 "should be updated only once per pause");
2767 _worker_cset_start_region[worker_i] = result;
2768 OrderAccess::storestore();
2769 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2770 return result;
2771 }
2772
2773 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2774 HeapRegion* r = g1_policy()->collection_set();
2775 while (r != NULL) {
2776 HeapRegion* next = r->next_in_collection_set();
2777 if (cl->doHeapRegion(r)) {
2778 cl->incomplete();
2779 return;
2780 }
2781 r = next;
2782 }
2783 }
2784
2785 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2786 HeapRegionClosure *cl) {
2787 if (r == NULL) {
2788 // The CSet is empty so there's nothing to do.
2789 return;
2790 }
2791
2792 assert(r->in_collection_set(),
2793 "Start region must be a member of the collection set.");
2794 HeapRegion* cur = r;
2795 while (cur != NULL) {
2796 HeapRegion* next = cur->next_in_collection_set();
2797 if (cl->doHeapRegion(cur) && false) {
2798 cl->incomplete();
2799 return;
2800 }
2801 cur = next;
2802 }
2803 cur = g1_policy()->collection_set();
2804 while (cur != r) {
2805 HeapRegion* next = cur->next_in_collection_set();
2806 if (cl->doHeapRegion(cur) && false) {
2807 cl->incomplete();
2808 return;
2809 }
2810 cur = next;
2811 }
2812 }
2813
2814 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2815 return n_regions() > 0 ? region_at(0) : NULL;
2816 }
2817
2818
2819 Space* G1CollectedHeap::space_containing(const void* addr) const {
2820 Space* res = heap_region_containing(addr);
2821 if (res == NULL)
2822 res = perm_gen()->space_containing(addr);
2823 return res;
2824 }
2825
2826 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2827 Space* sp = space_containing(addr);
2828 if (sp != NULL) {
2829 return sp->block_start(addr);
2830 }
2831 return NULL;
2832 }
2833
2834 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2835 Space* sp = space_containing(addr);
2836 assert(sp != NULL, "block_size of address outside of heap");
2837 return sp->block_size(addr);
2838 }
2839
2840 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2841 Space* sp = space_containing(addr);
2842 return sp->block_is_obj(addr);
2843 }
2844
2845 bool G1CollectedHeap::supports_tlab_allocation() const {
2846 return true;
2847 }
2848
2849 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2850 return HeapRegion::GrainBytes;
2851 }
2852
2853 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2854 // Return the remaining space in the cur alloc region, but not less than
2855 // the min TLAB size.
2856
2857 // Also, this value can be at most the humongous object threshold,
2858 // since we can't allow tlabs to grow big enough to accomodate
2859 // humongous objects.
2860
2861 HeapRegion* hr = _mutator_alloc_region.get();
2862 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2863 if (hr == NULL) {
2864 return max_tlab_size;
2865 } else {
2866 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2867 }
2868 }
2869
2870 size_t G1CollectedHeap::max_capacity() const {
2871 return _g1_reserved.byte_size();
2872 }
2873
2874 jlong G1CollectedHeap::millis_since_last_gc() {
2875 // assert(false, "NYI");
2876 return 0;
2877 }
2878
2879 void G1CollectedHeap::prepare_for_verify() {
2880 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2881 ensure_parsability(false);
2882 }
2883 g1_rem_set()->prepare_for_verify();
2884 }
2885
2886 class VerifyLivenessOopClosure: public OopClosure {
2887 G1CollectedHeap* _g1h;
2888 VerifyOption _vo;
2889 public:
2890 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2891 _g1h(g1h), _vo(vo)
2892 { }
2893 void do_oop(narrowOop *p) { do_oop_work(p); }
2894 void do_oop( oop *p) { do_oop_work(p); }
2895
2896 template <class T> void do_oop_work(T *p) {
2897 oop obj = oopDesc::load_decode_heap_oop(p);
2898 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2899 "Dead object referenced by a not dead object");
2900 }
2901 };
2902
2903 class VerifyObjsInRegionClosure: public ObjectClosure {
2904 private:
2905 G1CollectedHeap* _g1h;
2906 size_t _live_bytes;
2907 HeapRegion *_hr;
2908 VerifyOption _vo;
2909 public:
2910 // _vo == UsePrevMarking -> use "prev" marking information,
2911 // _vo == UseNextMarking -> use "next" marking information,
2912 // _vo == UseMarkWord -> use mark word from object header.
2913 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2914 : _live_bytes(0), _hr(hr), _vo(vo) {
2915 _g1h = G1CollectedHeap::heap();
2916 }
2917 void do_object(oop o) {
2918 VerifyLivenessOopClosure isLive(_g1h, _vo);
2919 assert(o != NULL, "Huh?");
2920 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2921 // If the object is alive according to the mark word,
2922 // then verify that the marking information agrees.
2923 // Note we can't verify the contra-positive of the
2924 // above: if the object is dead (according to the mark
2925 // word), it may not be marked, or may have been marked
2926 // but has since became dead, or may have been allocated
2927 // since the last marking.
2928 if (_vo == VerifyOption_G1UseMarkWord) {
2929 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2930 }
2931
2932 o->oop_iterate(&isLive);
2933 if (!_hr->obj_allocated_since_prev_marking(o)) {
2934 size_t obj_size = o->size(); // Make sure we don't overflow
2935 _live_bytes += (obj_size * HeapWordSize);
2936 }
2937 }
2938 }
2939 size_t live_bytes() { return _live_bytes; }
2940 };
2941
2942 class PrintObjsInRegionClosure : public ObjectClosure {
2943 HeapRegion *_hr;
2944 G1CollectedHeap *_g1;
2945 public:
2946 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2947 _g1 = G1CollectedHeap::heap();
2948 };
2949
2950 void do_object(oop o) {
2951 if (o != NULL) {
2952 HeapWord *start = (HeapWord *) o;
2953 size_t word_sz = o->size();
2954 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2955 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2956 (void*) o, word_sz,
2957 _g1->isMarkedPrev(o),
2958 _g1->isMarkedNext(o),
2959 _hr->obj_allocated_since_prev_marking(o));
2960 HeapWord *end = start + word_sz;
2961 HeapWord *cur;
2962 int *val;
2963 for (cur = start; cur < end; cur++) {
2964 val = (int *) cur;
2965 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2966 }
2967 }
2968 }
2969 };
2970
2971 class VerifyRegionClosure: public HeapRegionClosure {
2972 private:
2973 bool _allow_dirty;
2974 bool _par;
2975 VerifyOption _vo;
2976 bool _failures;
2977 public:
2978 // _vo == UsePrevMarking -> use "prev" marking information,
2979 // _vo == UseNextMarking -> use "next" marking information,
2980 // _vo == UseMarkWord -> use mark word from object header.
2981 VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
2982 : _allow_dirty(allow_dirty),
2983 _par(par),
2984 _vo(vo),
2985 _failures(false) {}
2986
2987 bool failures() {
2988 return _failures;
2989 }
2990
2991 bool doHeapRegion(HeapRegion* r) {
2992 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2993 "Should be unclaimed at verify points.");
2994 if (!r->continuesHumongous()) {
2995 bool failures = false;
2996 r->verify(_allow_dirty, _vo, &failures);
2997 if (failures) {
2998 _failures = true;
2999 } else {
3000 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3001 r->object_iterate(¬_dead_yet_cl);
3002 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3003 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3004 "max_live_bytes "SIZE_FORMAT" "
3005 "< calculated "SIZE_FORMAT,
3006 r->bottom(), r->end(),
3007 r->max_live_bytes(),
3008 not_dead_yet_cl.live_bytes());
3009 _failures = true;
3010 }
3011 }
3012 }
3013 return false; // stop the region iteration if we hit a failure
3014 }
3015 };
3016
3017 class VerifyRootsClosure: public OopsInGenClosure {
3018 private:
3019 G1CollectedHeap* _g1h;
3020 VerifyOption _vo;
3021 bool _failures;
3022 public:
3023 // _vo == UsePrevMarking -> use "prev" marking information,
3024 // _vo == UseNextMarking -> use "next" marking information,
3025 // _vo == UseMarkWord -> use mark word from object header.
3026 VerifyRootsClosure(VerifyOption vo) :
3027 _g1h(G1CollectedHeap::heap()),
3028 _vo(vo),
3029 _failures(false) { }
3030
3031 bool failures() { return _failures; }
3032
3033 template <class T> void do_oop_nv(T* p) {
3034 T heap_oop = oopDesc::load_heap_oop(p);
3035 if (!oopDesc::is_null(heap_oop)) {
3036 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3037 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3038 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3039 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3040 if (_vo == VerifyOption_G1UseMarkWord) {
3041 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3042 }
3043 obj->print_on(gclog_or_tty);
3044 _failures = true;
3045 }
3046 }
3047 }
3048
3049 void do_oop(oop* p) { do_oop_nv(p); }
3050 void do_oop(narrowOop* p) { do_oop_nv(p); }
3051 };
3052
3053 // This is the task used for parallel heap verification.
3054
3055 class G1ParVerifyTask: public AbstractGangTask {
3056 private:
3057 G1CollectedHeap* _g1h;
3058 bool _allow_dirty;
3059 VerifyOption _vo;
3060 bool _failures;
3061
3062 public:
3063 // _vo == UsePrevMarking -> use "prev" marking information,
3064 // _vo == UseNextMarking -> use "next" marking information,
3065 // _vo == UseMarkWord -> use mark word from object header.
3066 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
3067 AbstractGangTask("Parallel verify task"),
3068 _g1h(g1h),
3069 _allow_dirty(allow_dirty),
3070 _vo(vo),
3071 _failures(false) { }
3072
3073 bool failures() {
3074 return _failures;
3075 }
3076
3077 void work(int worker_i) {
3078 HandleMark hm;
3079 VerifyRegionClosure blk(_allow_dirty, true, _vo);
3080 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
3081 _g1h->workers()->active_workers(),
3082 HeapRegion::ParVerifyClaimValue);
3083 if (blk.failures()) {
3084 _failures = true;
3085 }
3086 }
3087 };
3088
3089 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
3090 verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
3091 }
3092
3093 void G1CollectedHeap::verify(bool allow_dirty,
3094 bool silent,
3095 VerifyOption vo) {
3096 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3097 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3098 VerifyRootsClosure rootsCl(vo);
3099
3100 assert(Thread::current()->is_VM_thread(),
3101 "Expected to be executed serially by the VM thread at this point");
3102
3103 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3104
3105 // We apply the relevant closures to all the oops in the
3106 // system dictionary, the string table and the code cache.
3107 const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
3108
3109 process_strong_roots(true, // activate StrongRootsScope
3110 true, // we set "collecting perm gen" to true,
3111 // so we don't reset the dirty cards in the perm gen.
3112 SharedHeap::ScanningOption(so), // roots scanning options
3113 &rootsCl,
3114 &blobsCl,
3115 &rootsCl);
3116
3117 // If we're verifying after the marking phase of a Full GC then we can't
3118 // treat the perm gen as roots into the G1 heap. Some of the objects in
3119 // the perm gen may be dead and hence not marked. If one of these dead
3120 // objects is considered to be a root then we may end up with a false
3121 // "Root location <x> points to dead ob <y>" failure.
3122 if (vo != VerifyOption_G1UseMarkWord) {
3123 // Since we used "collecting_perm_gen" == true above, we will not have
3124 // checked the refs from perm into the G1-collected heap. We check those
3125 // references explicitly below. Whether the relevant cards are dirty
3126 // is checked further below in the rem set verification.
3127 if (!silent) { gclog_or_tty->print("Permgen roots "); }
3128 perm_gen()->oop_iterate(&rootsCl);
3129 }
3130 bool failures = rootsCl.failures();
3131
3132 if (vo != VerifyOption_G1UseMarkWord) {
3133 // If we're verifying during a full GC then the region sets
3134 // will have been torn down at the start of the GC. Therefore
3135 // verifying the region sets will fail. So we only verify
3136 // the region sets when not in a full GC.
3137 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3138 verify_region_sets();
3139 }
3140
3141 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3142 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3143 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3144 "sanity check");
3145
3146 G1ParVerifyTask task(this, allow_dirty, vo);
3147 assert(UseDynamicNumberOfGCThreads ||
3148 workers()->active_workers() == workers()->total_workers(),
3149 "If not dynamic should be using all the workers");
3150 int n_workers = workers()->active_workers();
3151 set_par_threads(n_workers);
3152 workers()->run_task(&task);
3153 set_par_threads(0);
3154 if (task.failures()) {
3155 failures = true;
3156 }
3157
3158 // Checks that the expected amount of parallel work was done.
3159 // The implication is that n_workers is > 0.
3160 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3161 "sanity check");
3162
3163 reset_heap_region_claim_values();
3164
3165 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3166 "sanity check");
3167 } else {
3168 VerifyRegionClosure blk(allow_dirty, false, vo);
3169 heap_region_iterate(&blk);
3170 if (blk.failures()) {
3171 failures = true;
3172 }
3173 }
3174 if (!silent) gclog_or_tty->print("RemSet ");
3175 rem_set()->verify();
3176
3177 if (failures) {
3178 gclog_or_tty->print_cr("Heap:");
3179 // It helps to have the per-region information in the output to
3180 // help us track down what went wrong. This is why we call
3181 // print_extended_on() instead of print_on().
3182 print_extended_on(gclog_or_tty);
3183 gclog_or_tty->print_cr("");
3184 #ifndef PRODUCT
3185 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3186 concurrent_mark()->print_reachable("at-verification-failure",
3187 vo, false /* all */);
3188 }
3189 #endif
3190 gclog_or_tty->flush();
3191 }
3192 guarantee(!failures, "there should not have been any failures");
3193 } else {
3194 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3195 }
3196 }
3197
3198 class PrintRegionClosure: public HeapRegionClosure {
3199 outputStream* _st;
3200 public:
3201 PrintRegionClosure(outputStream* st) : _st(st) {}
3202 bool doHeapRegion(HeapRegion* r) {
3203 r->print_on(_st);
3204 return false;
3205 }
3206 };
3207
3208 void G1CollectedHeap::print_on(outputStream* st) const {
3209 st->print(" %-20s", "garbage-first heap");
3210 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3211 capacity()/K, used_unlocked()/K);
3212 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3213 _g1_storage.low_boundary(),
3214 _g1_storage.high(),
3215 _g1_storage.high_boundary());
3216 st->cr();
3217 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3218 size_t young_regions = _young_list->length();
3219 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3220 young_regions, young_regions * HeapRegion::GrainBytes / K);
3221 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3222 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3223 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3224 st->cr();
3225 perm()->as_gen()->print_on(st);
3226 }
3227
3228 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3229 print_on(st);
3230
3231 // Print the per-region information.
3232 st->cr();
3233 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), HS=humongous(starts), HC=humongous(continues), CS=collection set, F=free, TS=gc time stamp, PTAMS=previous top-at-mark-start, NTAMS=next top-at-mark-start)");
3234 PrintRegionClosure blk(st);
3235 heap_region_iterate(&blk);
3236 }
3237
3238 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3239 if (G1CollectedHeap::use_parallel_gc_threads()) {
3240 workers()->print_worker_threads_on(st);
3241 }
3242 _cmThread->print_on(st);
3243 st->cr();
3244 _cm->print_worker_threads_on(st);
3245 _cg1r->print_worker_threads_on(st);
3246 st->cr();
3247 }
3248
3249 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3250 if (G1CollectedHeap::use_parallel_gc_threads()) {
3251 workers()->threads_do(tc);
3252 }
3253 tc->do_thread(_cmThread);
3254 _cg1r->threads_do(tc);
3255 }
3256
3257 void G1CollectedHeap::print_tracing_info() const {
3258 // We'll overload this to mean "trace GC pause statistics."
3259 if (TraceGen0Time || TraceGen1Time) {
3260 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3261 // to that.
3262 g1_policy()->print_tracing_info();
3263 }
3264 if (G1SummarizeRSetStats) {
3265 g1_rem_set()->print_summary_info();
3266 }
3267 if (G1SummarizeConcMark) {
3268 concurrent_mark()->print_summary_info();
3269 }
3270 g1_policy()->print_yg_surv_rate_info();
3271 SpecializationStats::print();
3272 }
3273
3274 #ifndef PRODUCT
3275 // Helpful for debugging RSet issues.
3276
3277 class PrintRSetsClosure : public HeapRegionClosure {
3278 private:
3279 const char* _msg;
3280 size_t _occupied_sum;
3281
3282 public:
3283 bool doHeapRegion(HeapRegion* r) {
3284 HeapRegionRemSet* hrrs = r->rem_set();
3285 size_t occupied = hrrs->occupied();
3286 _occupied_sum += occupied;
3287
3288 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3289 HR_FORMAT_PARAMS(r));
3290 if (occupied == 0) {
3291 gclog_or_tty->print_cr(" RSet is empty");
3292 } else {
3293 hrrs->print();
3294 }
3295 gclog_or_tty->print_cr("----------");
3296 return false;
3297 }
3298
3299 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3300 gclog_or_tty->cr();
3301 gclog_or_tty->print_cr("========================================");
3302 gclog_or_tty->print_cr(msg);
3303 gclog_or_tty->cr();
3304 }
3305
3306 ~PrintRSetsClosure() {
3307 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3308 gclog_or_tty->print_cr("========================================");
3309 gclog_or_tty->cr();
3310 }
3311 };
3312
3313 void G1CollectedHeap::print_cset_rsets() {
3314 PrintRSetsClosure cl("Printing CSet RSets");
3315 collection_set_iterate(&cl);
3316 }
3317
3318 void G1CollectedHeap::print_all_rsets() {
3319 PrintRSetsClosure cl("Printing All RSets");;
3320 heap_region_iterate(&cl);
3321 }
3322 #endif // PRODUCT
3323
3324 G1CollectedHeap* G1CollectedHeap::heap() {
3325 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3326 "not a garbage-first heap");
3327 return _g1h;
3328 }
3329
3330 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3331 // always_do_update_barrier = false;
3332 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3333 // Call allocation profiler
3334 AllocationProfiler::iterate_since_last_gc();
3335 // Fill TLAB's and such
3336 ensure_parsability(true);
3337 }
3338
3339 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3340 // FIXME: what is this about?
3341 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3342 // is set.
3343 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3344 "derived pointer present"));
3345 // always_do_update_barrier = true;
3346
3347 // We have just completed a GC. Update the soft reference
3348 // policy with the new heap occupancy
3349 Universe::update_heap_info_at_gc();
3350 }
3351
3352 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3353 unsigned int gc_count_before,
3354 bool* succeeded) {
3355 assert_heap_not_locked_and_not_at_safepoint();
3356 g1_policy()->record_stop_world_start();
3357 VM_G1IncCollectionPause op(gc_count_before,
3358 word_size,
3359 false, /* should_initiate_conc_mark */
3360 g1_policy()->max_pause_time_ms(),
3361 GCCause::_g1_inc_collection_pause);
3362 VMThread::execute(&op);
3363
3364 HeapWord* result = op.result();
3365 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3366 assert(result == NULL || ret_succeeded,
3367 "the result should be NULL if the VM did not succeed");
3368 *succeeded = ret_succeeded;
3369
3370 assert_heap_not_locked();
3371 return result;
3372 }
3373
3374 void
3375 G1CollectedHeap::doConcurrentMark() {
3376 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3377 if (!_cmThread->in_progress()) {
3378 _cmThread->set_started();
3379 CGC_lock->notify();
3380 }
3381 }
3382
3383 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3384 bool young) {
3385 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3386 }
3387
3388 void G1CollectedHeap::check_if_region_is_too_expensive(double
3389 predicted_time_ms) {
3390 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3391 }
3392
3393 size_t G1CollectedHeap::pending_card_num() {
3394 size_t extra_cards = 0;
3395 JavaThread *curr = Threads::first();
3396 while (curr != NULL) {
3397 DirtyCardQueue& dcq = curr->dirty_card_queue();
3398 extra_cards += dcq.size();
3399 curr = curr->next();
3400 }
3401 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3402 size_t buffer_size = dcqs.buffer_size();
3403 size_t buffer_num = dcqs.completed_buffers_num();
3404 return buffer_size * buffer_num + extra_cards;
3405 }
3406
3407 size_t G1CollectedHeap::max_pending_card_num() {
3408 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3409 size_t buffer_size = dcqs.buffer_size();
3410 size_t buffer_num = dcqs.completed_buffers_num();
3411 int thread_num = Threads::number_of_threads();
3412 return (buffer_num + thread_num) * buffer_size;
3413 }
3414
3415 size_t G1CollectedHeap::cards_scanned() {
3416 return g1_rem_set()->cardsScanned();
3417 }
3418
3419 void
3420 G1CollectedHeap::setup_surviving_young_words() {
3421 guarantee( _surviving_young_words == NULL, "pre-condition" );
3422 size_t array_length = g1_policy()->young_cset_region_length();
3423 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3424 if (_surviving_young_words == NULL) {
3425 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3426 "Not enough space for young surv words summary.");
3427 }
3428 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3429 #ifdef ASSERT
3430 for (size_t i = 0; i < array_length; ++i) {
3431 assert( _surviving_young_words[i] == 0, "memset above" );
3432 }
3433 #endif // !ASSERT
3434 }
3435
3436 void
3437 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3438 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3439 size_t array_length = g1_policy()->young_cset_region_length();
3440 for (size_t i = 0; i < array_length; ++i)
3441 _surviving_young_words[i] += surv_young_words[i];
3442 }
3443
3444 void
3445 G1CollectedHeap::cleanup_surviving_young_words() {
3446 guarantee( _surviving_young_words != NULL, "pre-condition" );
3447 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3448 _surviving_young_words = NULL;
3449 }
3450
3451 #ifdef ASSERT
3452 class VerifyCSetClosure: public HeapRegionClosure {
3453 public:
3454 bool doHeapRegion(HeapRegion* hr) {
3455 // Here we check that the CSet region's RSet is ready for parallel
3456 // iteration. The fields that we'll verify are only manipulated
3457 // when the region is part of a CSet and is collected. Afterwards,
3458 // we reset these fields when we clear the region's RSet (when the
3459 // region is freed) so they are ready when the region is
3460 // re-allocated. The only exception to this is if there's an
3461 // evacuation failure and instead of freeing the region we leave
3462 // it in the heap. In that case, we reset these fields during
3463 // evacuation failure handling.
3464 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3465
3466 // Here's a good place to add any other checks we'd like to
3467 // perform on CSet regions.
3468 return false;
3469 }
3470 };
3471 #endif // ASSERT
3472
3473 #if TASKQUEUE_STATS
3474 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3475 st->print_raw_cr("GC Task Stats");
3476 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3477 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3478 }
3479
3480 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3481 print_taskqueue_stats_hdr(st);
3482
3483 TaskQueueStats totals;
3484 const int n = workers() != NULL ? workers()->total_workers() : 1;
3485 for (int i = 0; i < n; ++i) {
3486 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3487 totals += task_queue(i)->stats;
3488 }
3489 st->print_raw("tot "); totals.print(st); st->cr();
3490
3491 DEBUG_ONLY(totals.verify());
3492 }
3493
3494 void G1CollectedHeap::reset_taskqueue_stats() {
3495 const int n = workers() != NULL ? workers()->total_workers() : 1;
3496 for (int i = 0; i < n; ++i) {
3497 task_queue(i)->stats.reset();
3498 }
3499 }
3500 #endif // TASKQUEUE_STATS
3501
3502 bool
3503 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3504 assert_at_safepoint(true /* should_be_vm_thread */);
3505 guarantee(!is_gc_active(), "collection is not reentrant");
3506
3507 if (GC_locker::check_active_before_gc()) {
3508 return false;
3509 }
3510
3511 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3512 ResourceMark rm;
3513
3514 if (PrintHeapAtGC) {
3515 Universe::print_heap_before_gc();
3516 }
3517
3518 HRSPhaseSetter x(HRSPhaseEvacuation);
3519 verify_region_sets_optional();
3520 verify_dirty_young_regions();
3521
3522 {
3523 // This call will decide whether this pause is an initial-mark
3524 // pause. If it is, during_initial_mark_pause() will return true
3525 // for the duration of this pause.
3526 g1_policy()->decide_on_conc_mark_initiation();
3527
3528 // We do not allow initial-mark to be piggy-backed on a
3529 // partially-young GC.
3530 assert(!g1_policy()->during_initial_mark_pause() ||
3531 g1_policy()->full_young_gcs(), "sanity");
3532
3533 // We also do not allow partially-young GCs during marking.
3534 assert(!mark_in_progress() || g1_policy()->full_young_gcs(), "sanity");
3535
3536 char verbose_str[128];
3537 sprintf(verbose_str, "GC pause ");
3538 if (g1_policy()->full_young_gcs()) {
3539 strcat(verbose_str, "(young)");
3540 } else {
3541 strcat(verbose_str, "(partial)");
3542 }
3543 if (g1_policy()->during_initial_mark_pause()) {
3544 strcat(verbose_str, " (initial-mark)");
3545 // We are about to start a marking cycle, so we increment the
3546 // full collection counter.
3547 increment_total_full_collections();
3548 }
3549
3550 // if PrintGCDetails is on, we'll print long statistics information
3551 // in the collector policy code, so let's not print this as the output
3552 // is messy if we do.
3553 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3554 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3555 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3556
3557 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3558 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3559
3560 // If the secondary_free_list is not empty, append it to the
3561 // free_list. No need to wait for the cleanup operation to finish;
3562 // the region allocation code will check the secondary_free_list
3563 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3564 // set, skip this step so that the region allocation code has to
3565 // get entries from the secondary_free_list.
3566 if (!G1StressConcRegionFreeing) {
3567 append_secondary_free_list_if_not_empty_with_lock();
3568 }
3569
3570 assert(check_young_list_well_formed(),
3571 "young list should be well formed");
3572
3573 // Don't dynamically change the number of GC threads this early. A value of
3574 // 0 is used to indicate serial work. When parallel work is done,
3575 // it will be set.
3576
3577 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3578 IsGCActiveMark x;
3579
3580 gc_prologue(false);
3581 increment_total_collections(false /* full gc */);
3582 increment_gc_time_stamp();
3583
3584 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3585 HandleMark hm; // Discard invalid handles created during verification
3586 gclog_or_tty->print(" VerifyBeforeGC:");
3587 prepare_for_verify();
3588 Universe::verify(/* allow dirty */ false,
3589 /* silent */ false,
3590 /* option */ VerifyOption_G1UsePrevMarking);
3591
3592 }
3593
3594 COMPILER2_PRESENT(DerivedPointerTable::clear());
3595
3596 // Please see comment in g1CollectedHeap.hpp and
3597 // G1CollectedHeap::ref_processing_init() to see how
3598 // reference processing currently works in G1.
3599
3600 // Enable discovery in the STW reference processor
3601 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3602 true /*verify_no_refs*/);
3603
3604 {
3605 // We want to temporarily turn off discovery by the
3606 // CM ref processor, if necessary, and turn it back on
3607 // on again later if we do. Using a scoped
3608 // NoRefDiscovery object will do this.
3609 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3610
3611 // Forget the current alloc region (we might even choose it to be part
3612 // of the collection set!).
3613 release_mutator_alloc_region();
3614
3615 // We should call this after we retire the mutator alloc
3616 // region(s) so that all the ALLOC / RETIRE events are generated
3617 // before the start GC event.
3618 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3619
3620 // The elapsed time induced by the start time below deliberately elides
3621 // the possible verification above.
3622 double start_time_sec = os::elapsedTime();
3623 size_t start_used_bytes = used();
3624
3625 #if YOUNG_LIST_VERBOSE
3626 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3627 _young_list->print();
3628 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3629 #endif // YOUNG_LIST_VERBOSE
3630
3631 g1_policy()->record_collection_pause_start(start_time_sec,
3632 start_used_bytes);
3633
3634 #if YOUNG_LIST_VERBOSE
3635 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3636 _young_list->print();
3637 #endif // YOUNG_LIST_VERBOSE
3638
3639 if (g1_policy()->during_initial_mark_pause()) {
3640 concurrent_mark()->checkpointRootsInitialPre();
3641 }
3642 perm_gen()->save_marks();
3643
3644 // We must do this before any possible evacuation that should propagate
3645 // marks.
3646 if (mark_in_progress()) {
3647 double start_time_sec = os::elapsedTime();
3648
3649 _cm->drainAllSATBBuffers();
3650 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3651 g1_policy()->record_satb_drain_time(finish_mark_ms);
3652 }
3653 // Record the number of elements currently on the mark stack, so we
3654 // only iterate over these. (Since evacuation may add to the mark
3655 // stack, doing more exposes race conditions.) If no mark is in
3656 // progress, this will be zero.
3657 _cm->set_oops_do_bound();
3658
3659 if (mark_in_progress()) {
3660 concurrent_mark()->newCSet();
3661 }
3662
3663 #if YOUNG_LIST_VERBOSE
3664 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3665 _young_list->print();
3666 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3667 #endif // YOUNG_LIST_VERBOSE
3668
3669 g1_policy()->choose_collection_set(target_pause_time_ms);
3670
3671 if (_hr_printer.is_active()) {
3672 HeapRegion* hr = g1_policy()->collection_set();
3673 while (hr != NULL) {
3674 G1HRPrinter::RegionType type;
3675 if (!hr->is_young()) {
3676 type = G1HRPrinter::Old;
3677 } else if (hr->is_survivor()) {
3678 type = G1HRPrinter::Survivor;
3679 } else {
3680 type = G1HRPrinter::Eden;
3681 }
3682 _hr_printer.cset(hr);
3683 hr = hr->next_in_collection_set();
3684 }
3685 }
3686
3687 // We have chosen the complete collection set. If marking is
3688 // active then, we clear the region fields of any of the
3689 // concurrent marking tasks whose region fields point into
3690 // the collection set as these values will become stale. This
3691 // will cause the owning marking threads to claim a new region
3692 // when marking restarts.
3693 if (mark_in_progress()) {
3694 concurrent_mark()->reset_active_task_region_fields_in_cset();
3695 }
3696
3697 #ifdef ASSERT
3698 VerifyCSetClosure cl;
3699 collection_set_iterate(&cl);
3700 #endif // ASSERT
3701
3702 setup_surviving_young_words();
3703
3704 // Initialize the GC alloc regions.
3705 init_gc_alloc_regions();
3706
3707 // Actually do the work...
3708 evacuate_collection_set();
3709
3710 free_collection_set(g1_policy()->collection_set());
3711 g1_policy()->clear_collection_set();
3712
3713 cleanup_surviving_young_words();
3714
3715 // Start a new incremental collection set for the next pause.
3716 g1_policy()->start_incremental_cset_building();
3717
3718 // Clear the _cset_fast_test bitmap in anticipation of adding
3719 // regions to the incremental collection set for the next
3720 // evacuation pause.
3721 clear_cset_fast_test();
3722
3723 _young_list->reset_sampled_info();
3724
3725 // Don't check the whole heap at this point as the
3726 // GC alloc regions from this pause have been tagged
3727 // as survivors and moved on to the survivor list.
3728 // Survivor regions will fail the !is_young() check.
3729 assert(check_young_list_empty(false /* check_heap */),
3730 "young list should be empty");
3731
3732 #if YOUNG_LIST_VERBOSE
3733 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3734 _young_list->print();
3735 #endif // YOUNG_LIST_VERBOSE
3736
3737 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3738 _young_list->first_survivor_region(),
3739 _young_list->last_survivor_region());
3740
3741 _young_list->reset_auxilary_lists();
3742
3743 if (evacuation_failed()) {
3744 _summary_bytes_used = recalculate_used();
3745 } else {
3746 // The "used" of the the collection set have already been subtracted
3747 // when they were freed. Add in the bytes evacuated.
3748 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
3749 }
3750
3751 if (g1_policy()->during_initial_mark_pause()) {
3752 concurrent_mark()->checkpointRootsInitialPost();
3753 set_marking_started();
3754 // CAUTION: after the doConcurrentMark() call below,
3755 // the concurrent marking thread(s) could be running
3756 // concurrently with us. Make sure that anything after
3757 // this point does not assume that we are the only GC thread
3758 // running. Note: of course, the actual marking work will
3759 // not start until the safepoint itself is released in
3760 // ConcurrentGCThread::safepoint_desynchronize().
3761 doConcurrentMark();
3762 }
3763
3764 allocate_dummy_regions();
3765
3766 #if YOUNG_LIST_VERBOSE
3767 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3768 _young_list->print();
3769 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3770 #endif // YOUNG_LIST_VERBOSE
3771
3772 init_mutator_alloc_region();
3773
3774 {
3775 size_t expand_bytes = g1_policy()->expansion_amount();
3776 if (expand_bytes > 0) {
3777 size_t bytes_before = capacity();
3778 if (!expand(expand_bytes)) {
3779 // We failed to expand the heap so let's verify that
3780 // committed/uncommitted amount match the backing store
3781 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3782 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3783 }
3784 }
3785 }
3786
3787 double end_time_sec = os::elapsedTime();
3788 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3789 g1_policy()->record_pause_time_ms(pause_time_ms);
3790 int active_gc_threads = workers()->active_workers();
3791 g1_policy()->record_collection_pause_end(active_gc_threads);
3792
3793 MemoryService::track_memory_usage();
3794
3795 // In prepare_for_verify() below we'll need to scan the deferred
3796 // update buffers to bring the RSets up-to-date if
3797 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3798 // the update buffers we'll probably need to scan cards on the
3799 // regions we just allocated to (i.e., the GC alloc
3800 // regions). However, during the last GC we called
3801 // set_saved_mark() on all the GC alloc regions, so card
3802 // scanning might skip the [saved_mark_word()...top()] area of
3803 // those regions (i.e., the area we allocated objects into
3804 // during the last GC). But it shouldn't. Given that
3805 // saved_mark_word() is conditional on whether the GC time stamp
3806 // on the region is current or not, by incrementing the GC time
3807 // stamp here we invalidate all the GC time stamps on all the
3808 // regions and saved_mark_word() will simply return top() for
3809 // all the regions. This is a nicer way of ensuring this rather
3810 // than iterating over the regions and fixing them. In fact, the
3811 // GC time stamp increment here also ensures that
3812 // saved_mark_word() will return top() between pauses, i.e.,
3813 // during concurrent refinement. So we don't need the
3814 // is_gc_active() check to decided which top to use when
3815 // scanning cards (see CR 7039627).
3816 increment_gc_time_stamp();
3817
3818 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3819 HandleMark hm; // Discard invalid handles created during verification
3820 gclog_or_tty->print(" VerifyAfterGC:");
3821 prepare_for_verify();
3822 Universe::verify(/* allow dirty */ true,
3823 /* silent */ false,
3824 /* option */ VerifyOption_G1UsePrevMarking);
3825 }
3826
3827 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3828 ref_processor_stw()->verify_no_references_recorded();
3829
3830 // CM reference discovery will be re-enabled if necessary.
3831 }
3832
3833 {
3834 size_t expand_bytes = g1_policy()->expansion_amount();
3835 if (expand_bytes > 0) {
3836 size_t bytes_before = capacity();
3837 // No need for an ergo verbose message here,
3838 // expansion_amount() does this when it returns a value > 0.
3839 if (!expand(expand_bytes)) {
3840 // We failed to expand the heap so let's verify that
3841 // committed/uncommitted amount match the backing store
3842 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3843 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3844 }
3845 }
3846 }
3847
3848 // We should do this after we potentially expand the heap so
3849 // that all the COMMIT events are generated before the end GC
3850 // event, and after we retire the GC alloc regions so that all
3851 // RETIRE events are generated before the end GC event.
3852 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3853
3854 // We have to do this after we decide whether to expand the heap or not.
3855 g1_policy()->print_heap_transition();
3856
3857 if (mark_in_progress()) {
3858 concurrent_mark()->update_g1_committed();
3859 }
3860
3861 #ifdef TRACESPINNING
3862 ParallelTaskTerminator::print_termination_counts();
3863 #endif
3864
3865 gc_epilogue(false);
3866 }
3867
3868 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3869 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3870 print_tracing_info();
3871 vm_exit(-1);
3872 }
3873 }
3874
3875 _hrs.verify_optional();
3876 verify_region_sets_optional();
3877
3878 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3879 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3880
3881 if (PrintHeapAtGC) {
3882 Universe::print_heap_after_gc();
3883 }
3884 g1mm()->update_sizes();
3885
3886 if (G1SummarizeRSetStats &&
3887 (G1SummarizeRSetStatsPeriod > 0) &&
3888 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3889 g1_rem_set()->print_summary_info();
3890 }
3891
3892 return true;
3893 }
3894
3895 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3896 {
3897 size_t gclab_word_size;
3898 switch (purpose) {
3899 case GCAllocForSurvived:
3900 gclab_word_size = YoungPLABSize;
3901 break;
3902 case GCAllocForTenured:
3903 gclab_word_size = OldPLABSize;
3904 break;
3905 default:
3906 assert(false, "unknown GCAllocPurpose");
3907 gclab_word_size = OldPLABSize;
3908 break;
3909 }
3910 return gclab_word_size;
3911 }
3912
3913 void G1CollectedHeap::init_mutator_alloc_region() {
3914 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3915 _mutator_alloc_region.init();
3916 }
3917
3918 void G1CollectedHeap::release_mutator_alloc_region() {
3919 _mutator_alloc_region.release();
3920 assert(_mutator_alloc_region.get() == NULL, "post-condition");
3921 }
3922
3923 void G1CollectedHeap::init_gc_alloc_regions() {
3924 assert_at_safepoint(true /* should_be_vm_thread */);
3925
3926 _survivor_gc_alloc_region.init();
3927 _old_gc_alloc_region.init();
3928 HeapRegion* retained_region = _retained_old_gc_alloc_region;
3929 _retained_old_gc_alloc_region = NULL;
3930
3931 // We will discard the current GC alloc region if:
3932 // a) it's in the collection set (it can happen!),
3933 // b) it's already full (no point in using it),
3934 // c) it's empty (this means that it was emptied during
3935 // a cleanup and it should be on the free list now), or
3936 // d) it's humongous (this means that it was emptied
3937 // during a cleanup and was added to the free list, but
3938 // has been subseqently used to allocate a humongous
3939 // object that may be less than the region size).
3940 if (retained_region != NULL &&
3941 !retained_region->in_collection_set() &&
3942 !(retained_region->top() == retained_region->end()) &&
3943 !retained_region->is_empty() &&
3944 !retained_region->isHumongous()) {
3945 retained_region->set_saved_mark();
3946 // The retained region was added to the old region set when it was
3947 // retired. We have to remove it now, since we don't allow regions
3948 // we allocate to in the region sets. We'll re-add it later, when
3949 // it's retired again.
3950 _old_set.remove(retained_region);
3951 _old_gc_alloc_region.set(retained_region);
3952 _hr_printer.reuse(retained_region);
3953 }
3954 }
3955
3956 void G1CollectedHeap::release_gc_alloc_regions() {
3957 _survivor_gc_alloc_region.release();
3958 // If we have an old GC alloc region to release, we'll save it in
3959 // _retained_old_gc_alloc_region. If we don't
3960 // _retained_old_gc_alloc_region will become NULL. This is what we
3961 // want either way so no reason to check explicitly for either
3962 // condition.
3963 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
3964 }
3965
3966 void G1CollectedHeap::abandon_gc_alloc_regions() {
3967 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
3968 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
3969 _retained_old_gc_alloc_region = NULL;
3970 }
3971
3972 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3973 _drain_in_progress = false;
3974 set_evac_failure_closure(cl);
3975 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3976 }
3977
3978 void G1CollectedHeap::finalize_for_evac_failure() {
3979 assert(_evac_failure_scan_stack != NULL &&
3980 _evac_failure_scan_stack->length() == 0,
3981 "Postcondition");
3982 assert(!_drain_in_progress, "Postcondition");
3983 delete _evac_failure_scan_stack;
3984 _evac_failure_scan_stack = NULL;
3985 }
3986
3987 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3988 private:
3989 G1CollectedHeap* _g1;
3990 DirtyCardQueue *_dcq;
3991 CardTableModRefBS* _ct_bs;
3992
3993 public:
3994 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3995 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3996
3997 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3998 virtual void do_oop( oop* p) { do_oop_work(p); }
3999 template <class T> void do_oop_work(T* p) {
4000 assert(_from->is_in_reserved(p), "paranoia");
4001 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
4002 !_from->is_survivor()) {
4003 size_t card_index = _ct_bs->index_for(p);
4004 if (_ct_bs->mark_card_deferred(card_index)) {
4005 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
4006 }
4007 }
4008 }
4009 };
4010
4011 class RemoveSelfPointerClosure: public ObjectClosure {
4012 private:
4013 G1CollectedHeap* _g1;
4014 ConcurrentMark* _cm;
4015 HeapRegion* _hr;
4016 size_t _prev_marked_bytes;
4017 size_t _next_marked_bytes;
4018 OopsInHeapRegionClosure *_cl;
4019 public:
4020 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
4021 OopsInHeapRegionClosure* cl) :
4022 _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
4023 _next_marked_bytes(0), _cl(cl) {}
4024
4025 size_t prev_marked_bytes() { return _prev_marked_bytes; }
4026 size_t next_marked_bytes() { return _next_marked_bytes; }
4027
4028 // <original comment>
4029 // The original idea here was to coalesce evacuated and dead objects.
4030 // However that caused complications with the block offset table (BOT).
4031 // In particular if there were two TLABs, one of them partially refined.
4032 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
4033 // The BOT entries of the unrefined part of TLAB_2 point to the start
4034 // of TLAB_2. If the last object of the TLAB_1 and the first object
4035 // of TLAB_2 are coalesced, then the cards of the unrefined part
4036 // would point into middle of the filler object.
4037 // The current approach is to not coalesce and leave the BOT contents intact.
4038 // </original comment>
4039 //
4040 // We now reset the BOT when we start the object iteration over the
4041 // region and refine its entries for every object we come across. So
4042 // the above comment is not really relevant and we should be able
4043 // to coalesce dead objects if we want to.
4044 void do_object(oop obj) {
4045 HeapWord* obj_addr = (HeapWord*) obj;
4046 assert(_hr->is_in(obj_addr), "sanity");
4047 size_t obj_size = obj->size();
4048 _hr->update_bot_for_object(obj_addr, obj_size);
4049 if (obj->is_forwarded() && obj->forwardee() == obj) {
4050 // The object failed to move.
4051 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
4052 _cm->markPrev(obj);
4053 assert(_cm->isPrevMarked(obj), "Should be marked!");
4054 _prev_marked_bytes += (obj_size * HeapWordSize);
4055 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
4056 _cm->markAndGrayObjectIfNecessary(obj);
4057 }
4058 obj->set_mark(markOopDesc::prototype());
4059 // While we were processing RSet buffers during the
4060 // collection, we actually didn't scan any cards on the
4061 // collection set, since we didn't want to update remebered
4062 // sets with entries that point into the collection set, given
4063 // that live objects fromthe collection set are about to move
4064 // and such entries will be stale very soon. This change also
4065 // dealt with a reliability issue which involved scanning a
4066 // card in the collection set and coming across an array that
4067 // was being chunked and looking malformed. The problem is
4068 // that, if evacuation fails, we might have remembered set
4069 // entries missing given that we skipped cards on the
4070 // collection set. So, we'll recreate such entries now.
4071 obj->oop_iterate(_cl);
4072 assert(_cm->isPrevMarked(obj), "Should be marked!");
4073 } else {
4074 // The object has been either evacuated or is dead. Fill it with a
4075 // dummy object.
4076 MemRegion mr((HeapWord*)obj, obj_size);
4077 CollectedHeap::fill_with_object(mr);
4078 _cm->clearRangeBothMaps(mr);
4079 }
4080 }
4081 };
4082
4083 void G1CollectedHeap::remove_self_forwarding_pointers() {
4084 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
4085 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
4086 UpdateRSetDeferred deferred_update(_g1h, &dcq);
4087 OopsInHeapRegionClosure *cl;
4088 if (G1DeferredRSUpdate) {
4089 cl = &deferred_update;
4090 } else {
4091 cl = &immediate_update;
4092 }
4093 HeapRegion* cur = g1_policy()->collection_set();
4094 while (cur != NULL) {
4095 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4096 assert(!cur->isHumongous(), "sanity");
4097
4098 if (cur->evacuation_failed()) {
4099 assert(cur->in_collection_set(), "bad CS");
4100 RemoveSelfPointerClosure rspc(_g1h, cur, cl);
4101
4102 // In the common case we make sure that this is done when the
4103 // region is freed so that it is "ready-to-go" when it's
4104 // re-allocated. However, when evacuation failure happens, a
4105 // region will remain in the heap and might ultimately be added
4106 // to a CSet in the future. So we have to be careful here and
4107 // make sure the region's RSet is ready for parallel iteration
4108 // whenever this might be required in the future.
4109 cur->rem_set()->reset_for_par_iteration();
4110 cur->reset_bot();
4111 cl->set_region(cur);
4112 cur->object_iterate(&rspc);
4113
4114 // A number of manipulations to make the TAMS be the current top,
4115 // and the marked bytes be the ones observed in the iteration.
4116 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
4117 // The comments below are the postconditions achieved by the
4118 // calls. Note especially the last such condition, which says that
4119 // the count of marked bytes has been properly restored.
4120 cur->note_start_of_marking(false);
4121 // _next_top_at_mark_start == top, _next_marked_bytes == 0
4122 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
4123 // _next_marked_bytes == prev_marked_bytes.
4124 cur->note_end_of_marking();
4125 // _prev_top_at_mark_start == top(),
4126 // _prev_marked_bytes == prev_marked_bytes
4127 }
4128 // If there is no mark in progress, we modified the _next variables
4129 // above needlessly, but harmlessly.
4130 if (_g1h->mark_in_progress()) {
4131 cur->note_start_of_marking(false);
4132 // _next_top_at_mark_start == top, _next_marked_bytes == 0
4133 // _next_marked_bytes == next_marked_bytes.
4134 }
4135 }
4136 cur = cur->next_in_collection_set();
4137 }
4138 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4139
4140 // Now restore saved marks, if any.
4141 if (_objs_with_preserved_marks != NULL) {
4142 assert(_preserved_marks_of_objs != NULL, "Both or none.");
4143 guarantee(_objs_with_preserved_marks->length() ==
4144 _preserved_marks_of_objs->length(), "Both or none.");
4145 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
4146 oop obj = _objs_with_preserved_marks->at(i);
4147 markOop m = _preserved_marks_of_objs->at(i);
4148 obj->set_mark(m);
4149 }
4150 // Delete the preserved marks growable arrays (allocated on the C heap).
4151 delete _objs_with_preserved_marks;
4152 delete _preserved_marks_of_objs;
4153 _objs_with_preserved_marks = NULL;
4154 _preserved_marks_of_objs = NULL;
4155 }
4156 }
4157
4158 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4159 _evac_failure_scan_stack->push(obj);
4160 }
4161
4162 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4163 assert(_evac_failure_scan_stack != NULL, "precondition");
4164
4165 while (_evac_failure_scan_stack->length() > 0) {
4166 oop obj = _evac_failure_scan_stack->pop();
4167 _evac_failure_closure->set_region(heap_region_containing(obj));
4168 obj->oop_iterate_backwards(_evac_failure_closure);
4169 }
4170 }
4171
4172 oop
4173 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4174 oop old,
4175 bool should_mark_root) {
4176 assert(obj_in_cs(old),
4177 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4178 (HeapWord*) old));
4179 markOop m = old->mark();
4180 oop forward_ptr = old->forward_to_atomic(old);
4181 if (forward_ptr == NULL) {
4182 // Forward-to-self succeeded.
4183
4184 // should_mark_root will be true when this routine is called
4185 // from a root scanning closure during an initial mark pause.
4186 // In this case the thread that succeeds in self-forwarding the
4187 // object is also responsible for marking the object.
4188 if (should_mark_root) {
4189 assert(!oopDesc::is_null(old), "shouldn't be");
4190 _cm->grayRoot(old);
4191 }
4192
4193 if (_evac_failure_closure != cl) {
4194 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4195 assert(!_drain_in_progress,
4196 "Should only be true while someone holds the lock.");
4197 // Set the global evac-failure closure to the current thread's.
4198 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4199 set_evac_failure_closure(cl);
4200 // Now do the common part.
4201 handle_evacuation_failure_common(old, m);
4202 // Reset to NULL.
4203 set_evac_failure_closure(NULL);
4204 } else {
4205 // The lock is already held, and this is recursive.
4206 assert(_drain_in_progress, "This should only be the recursive case.");
4207 handle_evacuation_failure_common(old, m);
4208 }
4209 return old;
4210 } else {
4211 // Forward-to-self failed. Either someone else managed to allocate
4212 // space for this object (old != forward_ptr) or they beat us in
4213 // self-forwarding it (old == forward_ptr).
4214 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4215 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4216 "should not be in the CSet",
4217 (HeapWord*) old, (HeapWord*) forward_ptr));
4218 return forward_ptr;
4219 }
4220 }
4221
4222 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4223 set_evacuation_failed(true);
4224
4225 preserve_mark_if_necessary(old, m);
4226
4227 HeapRegion* r = heap_region_containing(old);
4228 if (!r->evacuation_failed()) {
4229 r->set_evacuation_failed(true);
4230 _hr_printer.evac_failure(r);
4231 }
4232
4233 push_on_evac_failure_scan_stack(old);
4234
4235 if (!_drain_in_progress) {
4236 // prevent recursion in copy_to_survivor_space()
4237 _drain_in_progress = true;
4238 drain_evac_failure_scan_stack();
4239 _drain_in_progress = false;
4240 }
4241 }
4242
4243 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4244 assert(evacuation_failed(), "Oversaving!");
4245 // We want to call the "for_promotion_failure" version only in the
4246 // case of a promotion failure.
4247 if (m->must_be_preserved_for_promotion_failure(obj)) {
4248 if (_objs_with_preserved_marks == NULL) {
4249 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4250 _objs_with_preserved_marks =
4251 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4252 _preserved_marks_of_objs =
4253 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4254 }
4255 _objs_with_preserved_marks->push(obj);
4256 _preserved_marks_of_objs->push(m);
4257 }
4258 }
4259
4260 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4261 size_t word_size) {
4262 if (purpose == GCAllocForSurvived) {
4263 HeapWord* result = survivor_attempt_allocation(word_size);
4264 if (result != NULL) {
4265 return result;
4266 } else {
4267 // Let's try to allocate in the old gen in case we can fit the
4268 // object there.
4269 return old_attempt_allocation(word_size);
4270 }
4271 } else {
4272 assert(purpose == GCAllocForTenured, "sanity");
4273 HeapWord* result = old_attempt_allocation(word_size);
4274 if (result != NULL) {
4275 return result;
4276 } else {
4277 // Let's try to allocate in the survivors in case we can fit the
4278 // object there.
4279 return survivor_attempt_allocation(word_size);
4280 }
4281 }
4282
4283 ShouldNotReachHere();
4284 // Trying to keep some compilers happy.
4285 return NULL;
4286 }
4287
4288 #ifndef PRODUCT
4289 bool GCLabBitMapClosure::do_bit(size_t offset) {
4290 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4291 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4292 return true;
4293 }
4294 #endif // PRODUCT
4295
4296 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4297 ParGCAllocBuffer(gclab_word_size),
4298 _should_mark_objects(false),
4299 _bitmap(G1CollectedHeap::heap()->reserved_region().start(), gclab_word_size),
4300 _retired(false)
4301 {
4302 //_should_mark_objects is set to true when G1ParCopyHelper needs to
4303 // mark the forwarded location of an evacuated object.
4304 // We set _should_mark_objects to true if marking is active, i.e. when we
4305 // need to propagate a mark, or during an initial mark pause, i.e. when we
4306 // need to mark objects immediately reachable by the roots.
4307 if (G1CollectedHeap::heap()->mark_in_progress() ||
4308 G1CollectedHeap::heap()->g1_policy()->during_initial_mark_pause()) {
4309 _should_mark_objects = true;
4310 }
4311 }
4312
4313 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4314 : _g1h(g1h),
4315 _refs(g1h->task_queue(queue_num)),
4316 _dcq(&g1h->dirty_card_queue_set()),
4317 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4318 _g1_rem(g1h->g1_rem_set()),
4319 _hash_seed(17), _queue_num(queue_num),
4320 _term_attempts(0),
4321 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4322 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4323 _age_table(false),
4324 _strong_roots_time(0), _term_time(0),
4325 _alloc_buffer_waste(0), _undo_waste(0)
4326 {
4327 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4328 // we "sacrifice" entry 0 to keep track of surviving bytes for
4329 // non-young regions (where the age is -1)
4330 // We also add a few elements at the beginning and at the end in
4331 // an attempt to eliminate cache contention
4332 size_t real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4333 size_t array_length = PADDING_ELEM_NUM +
4334 real_length +
4335 PADDING_ELEM_NUM;
4336 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4337 if (_surviving_young_words_base == NULL)
4338 vm_exit_out_of_memory(array_length * sizeof(size_t),
4339 "Not enough space for young surv histo.");
4340 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4341 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4342
4343 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4344 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4345
4346 _start = os::elapsedTime();
4347 }
4348
4349 void
4350 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4351 {
4352 st->print_raw_cr("GC Termination Stats");
4353 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4354 " ------waste (KiB)------");
4355 st->print_raw_cr("thr ms ms % ms % attempts"
4356 " total alloc undo");
4357 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4358 " ------- ------- -------");
4359 }
4360
4361 void
4362 G1ParScanThreadState::print_termination_stats(int i,
4363 outputStream* const st) const
4364 {
4365 const double elapsed_ms = elapsed_time() * 1000.0;
4366 const double s_roots_ms = strong_roots_time() * 1000.0;
4367 const double term_ms = term_time() * 1000.0;
4368 st->print_cr("%3d %9.2f %9.2f %6.2f "
4369 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4370 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4371 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4372 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4373 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4374 alloc_buffer_waste() * HeapWordSize / K,
4375 undo_waste() * HeapWordSize / K);
4376 }
4377
4378 #ifdef ASSERT
4379 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4380 assert(ref != NULL, "invariant");
4381 assert(UseCompressedOops, "sanity");
4382 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4383 oop p = oopDesc::load_decode_heap_oop(ref);
4384 assert(_g1h->is_in_g1_reserved(p),
4385 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4386 return true;
4387 }
4388
4389 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4390 assert(ref != NULL, "invariant");
4391 if (has_partial_array_mask(ref)) {
4392 // Must be in the collection set--it's already been copied.
4393 oop p = clear_partial_array_mask(ref);
4394 assert(_g1h->obj_in_cs(p),
4395 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4396 } else {
4397 oop p = oopDesc::load_decode_heap_oop(ref);
4398 assert(_g1h->is_in_g1_reserved(p),
4399 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4400 }
4401 return true;
4402 }
4403
4404 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4405 if (ref.is_narrow()) {
4406 return verify_ref((narrowOop*) ref);
4407 } else {
4408 return verify_ref((oop*) ref);
4409 }
4410 }
4411 #endif // ASSERT
4412
4413 void G1ParScanThreadState::trim_queue() {
4414 assert(_evac_cl != NULL, "not set");
4415 assert(_evac_failure_cl != NULL, "not set");
4416 assert(_partial_scan_cl != NULL, "not set");
4417
4418 StarTask ref;
4419 do {
4420 // Drain the overflow stack first, so other threads can steal.
4421 while (refs()->pop_overflow(ref)) {
4422 deal_with_reference(ref);
4423 }
4424
4425 while (refs()->pop_local(ref)) {
4426 deal_with_reference(ref);
4427 }
4428 } while (!refs()->is_empty());
4429 }
4430
4431 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4432 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4433 _par_scan_state(par_scan_state),
4434 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4435 _mark_in_progress(_g1->mark_in_progress()) { }
4436
4437 template <class T> void G1ParCopyHelper::mark_object(T* p) {
4438 // This is called from do_oop_work for objects that are not
4439 // in the collection set. Objects in the collection set
4440 // are marked after they have been evacuated.
4441
4442 T heap_oop = oopDesc::load_heap_oop(p);
4443 if (!oopDesc::is_null(heap_oop)) {
4444 oop obj = oopDesc::decode_heap_oop(heap_oop);
4445 HeapWord* addr = (HeapWord*)obj;
4446 if (_g1->is_in_g1_reserved(addr)) {
4447 _cm->grayRoot(oop(addr));
4448 }
4449 }
4450 }
4451
4452 oop G1ParCopyHelper::copy_to_survivor_space(oop old, bool should_mark_root,
4453 bool should_mark_copy) {
4454 size_t word_sz = old->size();
4455 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4456 // +1 to make the -1 indexes valid...
4457 int young_index = from_region->young_index_in_cset()+1;
4458 assert( (from_region->is_young() && young_index > 0) ||
4459 (!from_region->is_young() && young_index == 0), "invariant" );
4460 G1CollectorPolicy* g1p = _g1->g1_policy();
4461 markOop m = old->mark();
4462 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4463 : m->age();
4464 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4465 word_sz);
4466 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4467 oop obj = oop(obj_ptr);
4468
4469 if (obj_ptr == NULL) {
4470 // This will either forward-to-self, or detect that someone else has
4471 // installed a forwarding pointer.
4472 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4473 return _g1->handle_evacuation_failure_par(cl, old, should_mark_root);
4474 }
4475
4476 // We're going to allocate linearly, so might as well prefetch ahead.
4477 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4478
4479 oop forward_ptr = old->forward_to_atomic(obj);
4480 if (forward_ptr == NULL) {
4481 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4482 if (g1p->track_object_age(alloc_purpose)) {
4483 // We could simply do obj->incr_age(). However, this causes a
4484 // performance issue. obj->incr_age() will first check whether
4485 // the object has a displaced mark by checking its mark word;
4486 // getting the mark word from the new location of the object
4487 // stalls. So, given that we already have the mark word and we
4488 // are about to install it anyway, it's better to increase the
4489 // age on the mark word, when the object does not have a
4490 // displaced mark word. We're not expecting many objects to have
4491 // a displaced marked word, so that case is not optimized
4492 // further (it could be...) and we simply call obj->incr_age().
4493
4494 if (m->has_displaced_mark_helper()) {
4495 // in this case, we have to install the mark word first,
4496 // otherwise obj looks to be forwarded (the old mark word,
4497 // which contains the forward pointer, was copied)
4498 obj->set_mark(m);
4499 obj->incr_age();
4500 } else {
4501 m = m->incr_age();
4502 obj->set_mark(m);
4503 }
4504 _par_scan_state->age_table()->add(obj, word_sz);
4505 } else {
4506 obj->set_mark(m);
4507 }
4508
4509 // Mark the evacuated object or propagate "next" mark bit
4510 if (should_mark_copy) {
4511 if (!use_local_bitmaps ||
4512 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4513 // if we couldn't mark it on the local bitmap (this happens when
4514 // the object was not allocated in the GCLab), we have to bite
4515 // the bullet and do the standard parallel mark
4516 _cm->markAndGrayObjectIfNecessary(obj);
4517 }
4518
4519 if (_g1->isMarkedNext(old)) {
4520 // Unmark the object's old location so that marking
4521 // doesn't think the old object is alive.
4522 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4523 }
4524 }
4525
4526 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4527 surv_young_words[young_index] += word_sz;
4528
4529 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4530 arrayOop(old)->set_length(0);
4531 oop* old_p = set_partial_array_mask(old);
4532 _par_scan_state->push_on_queue(old_p);
4533 } else {
4534 // No point in using the slower heap_region_containing() method,
4535 // given that we know obj is in the heap.
4536 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4537 obj->oop_iterate_backwards(_scanner);
4538 }
4539 } else {
4540 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4541 obj = forward_ptr;
4542 }
4543 return obj;
4544 }
4545
4546 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4547 template <class T>
4548 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4549 ::do_oop_work(T* p) {
4550 oop obj = oopDesc::load_decode_heap_oop(p);
4551 assert(barrier != G1BarrierRS || obj != NULL,
4552 "Precondition: G1BarrierRS implies obj is nonNull");
4553
4554 // Marking:
4555 // If the object is in the collection set, then the thread
4556 // that copies the object should mark, or propagate the
4557 // mark to, the evacuated object.
4558 // If the object is not in the collection set then we
4559 // should call the mark_object() method depending on the
4560 // value of the template parameter do_mark_object (which will
4561 // be true for root scanning closures during an initial mark
4562 // pause).
4563 // The mark_object() method first checks whether the object
4564 // is marked and, if not, attempts to mark the object.
4565
4566 // here the null check is implicit in the cset_fast_test() test
4567 if (_g1->in_cset_fast_test(obj)) {
4568 if (obj->is_forwarded()) {
4569 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4570 // If we are a root scanning closure during an initial
4571 // mark pause (i.e. do_mark_object will be true) then
4572 // we also need to handle marking of roots in the
4573 // event of an evacuation failure. In the event of an
4574 // evacuation failure, the object is forwarded to itself
4575 // and not copied. For root-scanning closures, the
4576 // object would be marked after a successful self-forward
4577 // but an object could be pointed to by both a root and non
4578 // root location and be self-forwarded by a non-root-scanning
4579 // closure. Therefore we also have to attempt to mark the
4580 // self-forwarded root object here.
4581 if (do_mark_object && obj->forwardee() == obj) {
4582 mark_object(p);
4583 }
4584 } else {
4585 // During an initial mark pause, objects that are pointed to
4586 // by the roots need to be marked - even in the event of an
4587 // evacuation failure. We pass the template parameter
4588 // do_mark_object (which is true for root scanning closures
4589 // during an initial mark pause) to copy_to_survivor_space
4590 // which will pass it on to the evacuation failure handling
4591 // code. The thread that successfully self-forwards a root
4592 // object to itself is responsible for marking the object.
4593 bool should_mark_root = do_mark_object;
4594
4595 // We need to mark the copied object if we're a root scanning
4596 // closure during an initial mark pause (i.e. do_mark_object
4597 // will be true), or the object is already marked and we need
4598 // to propagate the mark to the evacuated copy.
4599 bool should_mark_copy = do_mark_object ||
4600 _during_initial_mark ||
4601 (_mark_in_progress && !_g1->is_obj_ill(obj));
4602
4603 oop copy_oop = copy_to_survivor_space(obj, should_mark_root,
4604 should_mark_copy);
4605 oopDesc::encode_store_heap_oop(p, copy_oop);
4606 }
4607 // When scanning the RS, we only care about objs in CS.
4608 if (barrier == G1BarrierRS) {
4609 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4610 }
4611 } else {
4612 // The object is not in collection set. If we're a root scanning
4613 // closure during an initial mark pause (i.e. do_mark_object will
4614 // be true) then attempt to mark the object.
4615 if (do_mark_object) {
4616 mark_object(p);
4617 }
4618 }
4619
4620 if (barrier == G1BarrierEvac && obj != NULL) {
4621 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4622 }
4623
4624 if (do_gen_barrier && obj != NULL) {
4625 par_do_barrier(p);
4626 }
4627 }
4628
4629 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4630 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4631
4632 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4633 assert(has_partial_array_mask(p), "invariant");
4634 oop old = clear_partial_array_mask(p);
4635 assert(old->is_objArray(), "must be obj array");
4636 assert(old->is_forwarded(), "must be forwarded");
4637 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4638
4639 objArrayOop obj = objArrayOop(old->forwardee());
4640 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4641 // Process ParGCArrayScanChunk elements now
4642 // and push the remainder back onto queue
4643 int start = arrayOop(old)->length();
4644 int end = obj->length();
4645 int remainder = end - start;
4646 assert(start <= end, "just checking");
4647 if (remainder > 2 * ParGCArrayScanChunk) {
4648 // Test above combines last partial chunk with a full chunk
4649 end = start + ParGCArrayScanChunk;
4650 arrayOop(old)->set_length(end);
4651 // Push remainder.
4652 oop* old_p = set_partial_array_mask(old);
4653 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4654 _par_scan_state->push_on_queue(old_p);
4655 } else {
4656 // Restore length so that the heap remains parsable in
4657 // case of evacuation failure.
4658 arrayOop(old)->set_length(end);
4659 }
4660 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4661 // process our set of indices (include header in first chunk)
4662 obj->oop_iterate_range(&_scanner, start, end);
4663 }
4664
4665 class G1ParEvacuateFollowersClosure : public VoidClosure {
4666 protected:
4667 G1CollectedHeap* _g1h;
4668 G1ParScanThreadState* _par_scan_state;
4669 RefToScanQueueSet* _queues;
4670 ParallelTaskTerminator* _terminator;
4671
4672 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4673 RefToScanQueueSet* queues() { return _queues; }
4674 ParallelTaskTerminator* terminator() { return _terminator; }
4675
4676 public:
4677 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4678 G1ParScanThreadState* par_scan_state,
4679 RefToScanQueueSet* queues,
4680 ParallelTaskTerminator* terminator)
4681 : _g1h(g1h), _par_scan_state(par_scan_state),
4682 _queues(queues), _terminator(terminator) {}
4683
4684 void do_void();
4685
4686 private:
4687 inline bool offer_termination();
4688 };
4689
4690 bool G1ParEvacuateFollowersClosure::offer_termination() {
4691 G1ParScanThreadState* const pss = par_scan_state();
4692 pss->start_term_time();
4693 const bool res = terminator()->offer_termination();
4694 pss->end_term_time();
4695 return res;
4696 }
4697
4698 void G1ParEvacuateFollowersClosure::do_void() {
4699 StarTask stolen_task;
4700 G1ParScanThreadState* const pss = par_scan_state();
4701 pss->trim_queue();
4702
4703 do {
4704 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4705 assert(pss->verify_task(stolen_task), "sanity");
4706 if (stolen_task.is_narrow()) {
4707 pss->deal_with_reference((narrowOop*) stolen_task);
4708 } else {
4709 pss->deal_with_reference((oop*) stolen_task);
4710 }
4711
4712 // We've just processed a reference and we might have made
4713 // available new entries on the queues. So we have to make sure
4714 // we drain the queues as necessary.
4715 pss->trim_queue();
4716 }
4717 } while (!offer_termination());
4718
4719 pss->retire_alloc_buffers();
4720 }
4721
4722 class G1ParTask : public AbstractGangTask {
4723 protected:
4724 G1CollectedHeap* _g1h;
4725 RefToScanQueueSet *_queues;
4726 ParallelTaskTerminator _terminator;
4727 int _n_workers;
4728
4729 Mutex _stats_lock;
4730 Mutex* stats_lock() { return &_stats_lock; }
4731
4732 size_t getNCards() {
4733 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4734 / G1BlockOffsetSharedArray::N_bytes;
4735 }
4736
4737 public:
4738 G1ParTask(G1CollectedHeap* g1h,
4739 RefToScanQueueSet *task_queues)
4740 : AbstractGangTask("G1 collection"),
4741 _g1h(g1h),
4742 _queues(task_queues),
4743 _terminator(0, _queues),
4744 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4745 {}
4746
4747 RefToScanQueueSet* queues() { return _queues; }
4748
4749 RefToScanQueue *work_queue(int i) {
4750 return queues()->queue(i);
4751 }
4752
4753 ParallelTaskTerminator* terminator() { return &_terminator; }
4754
4755 virtual void set_for_termination(int active_workers) {
4756 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4757 // in the young space (_par_seq_tasks) in the G1 heap
4758 // for SequentialSubTasksDone.
4759 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4760 // both of which need setting by set_n_termination().
4761 _g1h->SharedHeap::set_n_termination(active_workers);
4762 _g1h->set_n_termination(active_workers);
4763 terminator()->reset_for_reuse(active_workers);
4764 _n_workers = active_workers;
4765 }
4766
4767 void work(int i) {
4768 if (i >= _n_workers) return; // no work needed this round
4769
4770 double start_time_ms = os::elapsedTime() * 1000.0;
4771 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4772
4773 ResourceMark rm;
4774 HandleMark hm;
4775
4776 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4777
4778 G1ParScanThreadState pss(_g1h, i);
4779 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4780 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4781 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4782
4783 pss.set_evac_closure(&scan_evac_cl);
4784 pss.set_evac_failure_closure(&evac_failure_cl);
4785 pss.set_partial_scan_closure(&partial_scan_cl);
4786
4787 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4788 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp);
4789
4790 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4791 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp);
4792
4793 OopClosure* scan_root_cl = &only_scan_root_cl;
4794 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl;
4795
4796 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4797 // We also need to mark copied objects.
4798 scan_root_cl = &scan_mark_root_cl;
4799 scan_perm_cl = &scan_mark_perm_cl;
4800 }
4801
4802 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4803
4804 pss.start_strong_roots();
4805 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4806 SharedHeap::SO_AllClasses,
4807 scan_root_cl,
4808 &push_heap_rs_cl,
4809 scan_perm_cl,
4810 i);
4811 pss.end_strong_roots();
4812
4813 {
4814 double start = os::elapsedTime();
4815 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4816 evac.do_void();
4817 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4818 double term_ms = pss.term_time()*1000.0;
4819 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4820 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4821 }
4822 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4823 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4824
4825 // Clean up any par-expanded rem sets.
4826 HeapRegionRemSet::par_cleanup();
4827
4828 if (ParallelGCVerbose) {
4829 MutexLocker x(stats_lock());
4830 pss.print_termination_stats(i);
4831 }
4832
4833 assert(pss.refs()->is_empty(), "should be empty");
4834 double end_time_ms = os::elapsedTime() * 1000.0;
4835 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4836 }
4837 };
4838
4839 // *** Common G1 Evacuation Stuff
4840
4841 // This method is run in a GC worker.
4842
4843 void
4844 G1CollectedHeap::
4845 g1_process_strong_roots(bool collecting_perm_gen,
4846 SharedHeap::ScanningOption so,
4847 OopClosure* scan_non_heap_roots,
4848 OopsInHeapRegionClosure* scan_rs,
4849 OopsInGenClosure* scan_perm,
4850 int worker_i) {
4851
4852 // First scan the strong roots, including the perm gen.
4853 double ext_roots_start = os::elapsedTime();
4854 double closure_app_time_sec = 0.0;
4855
4856 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4857 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4858 buf_scan_perm.set_generation(perm_gen());
4859
4860 // Walk the code cache w/o buffering, because StarTask cannot handle
4861 // unaligned oop locations.
4862 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4863
4864 process_strong_roots(false, // no scoping; this is parallel code
4865 collecting_perm_gen, so,
4866 &buf_scan_non_heap_roots,
4867 &eager_scan_code_roots,
4868 &buf_scan_perm);
4869
4870 // Now the CM ref_processor roots.
4871 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4872 // We need to treat the discovered reference lists of the
4873 // concurrent mark ref processor as roots and keep entries
4874 // (which are added by the marking threads) on them live
4875 // until they can be processed at the end of marking.
4876 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4877 }
4878
4879 // Finish up any enqueued closure apps (attributed as object copy time).
4880 buf_scan_non_heap_roots.done();
4881 buf_scan_perm.done();
4882
4883 double ext_roots_end = os::elapsedTime();
4884
4885 g1_policy()->reset_obj_copy_time(worker_i);
4886 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4887 buf_scan_non_heap_roots.closure_app_seconds();
4888 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4889
4890 double ext_root_time_ms =
4891 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4892
4893 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4894
4895 // Scan strong roots in mark stack.
4896 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4897 concurrent_mark()->oops_do(scan_non_heap_roots);
4898 }
4899 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4900 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4901
4902 // Now scan the complement of the collection set.
4903 if (scan_rs != NULL) {
4904 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4905 }
4906
4907 _process_strong_tasks->all_tasks_completed();
4908 }
4909
4910 void
4911 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4912 OopClosure* non_root_closure) {
4913 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4914 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4915 }
4916
4917 // Weak Reference Processing support
4918
4919 // An always "is_alive" closure that is used to preserve referents.
4920 // If the object is non-null then it's alive. Used in the preservation
4921 // of referent objects that are pointed to by reference objects
4922 // discovered by the CM ref processor.
4923 class G1AlwaysAliveClosure: public BoolObjectClosure {
4924 G1CollectedHeap* _g1;
4925 public:
4926 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4927 void do_object(oop p) { assert(false, "Do not call."); }
4928 bool do_object_b(oop p) {
4929 if (p != NULL) {
4930 return true;
4931 }
4932 return false;
4933 }
4934 };
4935
4936 bool G1STWIsAliveClosure::do_object_b(oop p) {
4937 // An object is reachable if it is outside the collection set,
4938 // or is inside and copied.
4939 return !_g1->obj_in_cs(p) || p->is_forwarded();
4940 }
4941
4942 // Non Copying Keep Alive closure
4943 class G1KeepAliveClosure: public OopClosure {
4944 G1CollectedHeap* _g1;
4945 public:
4946 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4947 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4948 void do_oop( oop* p) {
4949 oop obj = *p;
4950
4951 if (_g1->obj_in_cs(obj)) {
4952 assert( obj->is_forwarded(), "invariant" );
4953 *p = obj->forwardee();
4954 }
4955 }
4956 };
4957
4958 // Copying Keep Alive closure - can be called from both
4959 // serial and parallel code as long as different worker
4960 // threads utilize different G1ParScanThreadState instances
4961 // and different queues.
4962
4963 class G1CopyingKeepAliveClosure: public OopClosure {
4964 G1CollectedHeap* _g1h;
4965 OopClosure* _copy_non_heap_obj_cl;
4966 OopsInHeapRegionClosure* _copy_perm_obj_cl;
4967 G1ParScanThreadState* _par_scan_state;
4968
4969 public:
4970 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4971 OopClosure* non_heap_obj_cl,
4972 OopsInHeapRegionClosure* perm_obj_cl,
4973 G1ParScanThreadState* pss):
4974 _g1h(g1h),
4975 _copy_non_heap_obj_cl(non_heap_obj_cl),
4976 _copy_perm_obj_cl(perm_obj_cl),
4977 _par_scan_state(pss)
4978 {}
4979
4980 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4981 virtual void do_oop( oop* p) { do_oop_work(p); }
4982
4983 template <class T> void do_oop_work(T* p) {
4984 oop obj = oopDesc::load_decode_heap_oop(p);
4985
4986 if (_g1h->obj_in_cs(obj)) {
4987 // If the referent object has been forwarded (either copied
4988 // to a new location or to itself in the event of an
4989 // evacuation failure) then we need to update the reference
4990 // field and, if both reference and referent are in the G1
4991 // heap, update the RSet for the referent.
4992 //
4993 // If the referent has not been forwarded then we have to keep
4994 // it alive by policy. Therefore we have copy the referent.
4995 //
4996 // If the reference field is in the G1 heap then we can push
4997 // on the PSS queue. When the queue is drained (after each
4998 // phase of reference processing) the object and it's followers
4999 // will be copied, the reference field set to point to the
5000 // new location, and the RSet updated. Otherwise we need to
5001 // use the the non-heap or perm closures directly to copy
5002 // the refernt object and update the pointer, while avoiding
5003 // updating the RSet.
5004
5005 if (_g1h->is_in_g1_reserved(p)) {
5006 _par_scan_state->push_on_queue(p);
5007 } else {
5008 // The reference field is not in the G1 heap.
5009 if (_g1h->perm_gen()->is_in(p)) {
5010 _copy_perm_obj_cl->do_oop(p);
5011 } else {
5012 _copy_non_heap_obj_cl->do_oop(p);
5013 }
5014 }
5015 }
5016 }
5017 };
5018
5019 // Serial drain queue closure. Called as the 'complete_gc'
5020 // closure for each discovered list in some of the
5021 // reference processing phases.
5022
5023 class G1STWDrainQueueClosure: public VoidClosure {
5024 protected:
5025 G1CollectedHeap* _g1h;
5026 G1ParScanThreadState* _par_scan_state;
5027
5028 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5029
5030 public:
5031 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5032 _g1h(g1h),
5033 _par_scan_state(pss)
5034 { }
5035
5036 void do_void() {
5037 G1ParScanThreadState* const pss = par_scan_state();
5038 pss->trim_queue();
5039 }
5040 };
5041
5042 // Parallel Reference Processing closures
5043
5044 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5045 // processing during G1 evacuation pauses.
5046
5047 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5048 private:
5049 G1CollectedHeap* _g1h;
5050 RefToScanQueueSet* _queues;
5051 FlexibleWorkGang* _workers;
5052 int _active_workers;
5053
5054 public:
5055 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5056 FlexibleWorkGang* workers,
5057 RefToScanQueueSet *task_queues,
5058 int n_workers) :
5059 _g1h(g1h),
5060 _queues(task_queues),
5061 _workers(workers),
5062 _active_workers(n_workers)
5063 {
5064 assert(n_workers > 0, "shouldn't call this otherwise");
5065 }
5066
5067 // Executes the given task using concurrent marking worker threads.
5068 virtual void execute(ProcessTask& task);
5069 virtual void execute(EnqueueTask& task);
5070 };
5071
5072 // Gang task for possibly parallel reference processing
5073
5074 class G1STWRefProcTaskProxy: public AbstractGangTask {
5075 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5076 ProcessTask& _proc_task;
5077 G1CollectedHeap* _g1h;
5078 RefToScanQueueSet *_task_queues;
5079 ParallelTaskTerminator* _terminator;
5080
5081 public:
5082 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5083 G1CollectedHeap* g1h,
5084 RefToScanQueueSet *task_queues,
5085 ParallelTaskTerminator* terminator) :
5086 AbstractGangTask("Process reference objects in parallel"),
5087 _proc_task(proc_task),
5088 _g1h(g1h),
5089 _task_queues(task_queues),
5090 _terminator(terminator)
5091 {}
5092
5093 virtual void work(int i) {
5094 // The reference processing task executed by a single worker.
5095 ResourceMark rm;
5096 HandleMark hm;
5097
5098 G1STWIsAliveClosure is_alive(_g1h);
5099
5100 G1ParScanThreadState pss(_g1h, i);
5101
5102 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5103 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5104 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5105
5106 pss.set_evac_closure(&scan_evac_cl);
5107 pss.set_evac_failure_closure(&evac_failure_cl);
5108 pss.set_partial_scan_closure(&partial_scan_cl);
5109
5110 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5111 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5112
5113 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5114 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5115
5116 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5117 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5118
5119 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5120 // We also need to mark copied objects.
5121 copy_non_heap_cl = ©_mark_non_heap_cl;
5122 copy_perm_cl = ©_mark_perm_cl;
5123 }
5124
5125 // Keep alive closure.
5126 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5127
5128 // Complete GC closure
5129 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5130
5131 // Call the reference processing task's work routine.
5132 _proc_task.work(i, is_alive, keep_alive, drain_queue);
5133
5134 // Note we cannot assert that the refs array is empty here as not all
5135 // of the processing tasks (specifically phase2 - pp2_work) execute
5136 // the complete_gc closure (which ordinarily would drain the queue) so
5137 // the queue may not be empty.
5138 }
5139 };
5140
5141 // Driver routine for parallel reference processing.
5142 // Creates an instance of the ref processing gang
5143 // task and has the worker threads execute it.
5144 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5145 assert(_workers != NULL, "Need parallel worker threads.");
5146
5147 ParallelTaskTerminator terminator(_active_workers, _queues);
5148 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5149
5150 _g1h->set_par_threads(_active_workers);
5151 _workers->run_task(&proc_task_proxy);
5152 _g1h->set_par_threads(0);
5153 }
5154
5155 // Gang task for parallel reference enqueueing.
5156
5157 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5158 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5159 EnqueueTask& _enq_task;
5160
5161 public:
5162 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5163 AbstractGangTask("Enqueue reference objects in parallel"),
5164 _enq_task(enq_task)
5165 { }
5166
5167 virtual void work(int i) {
5168 _enq_task.work(i);
5169 }
5170 };
5171
5172 // Driver routine for parallel reference enqueing.
5173 // Creates an instance of the ref enqueueing gang
5174 // task and has the worker threads execute it.
5175
5176 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5177 assert(_workers != NULL, "Need parallel worker threads.");
5178
5179 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5180
5181 _g1h->set_par_threads(_active_workers);
5182 _workers->run_task(&enq_task_proxy);
5183 _g1h->set_par_threads(0);
5184 }
5185
5186 // End of weak reference support closures
5187
5188 // Abstract task used to preserve (i.e. copy) any referent objects
5189 // that are in the collection set and are pointed to by reference
5190 // objects discovered by the CM ref processor.
5191
5192 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5193 protected:
5194 G1CollectedHeap* _g1h;
5195 RefToScanQueueSet *_queues;
5196 ParallelTaskTerminator _terminator;
5197 int _n_workers;
5198
5199 public:
5200 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5201 AbstractGangTask("ParPreserveCMReferents"),
5202 _g1h(g1h),
5203 _queues(task_queues),
5204 _terminator(workers, _queues),
5205 _n_workers(workers)
5206 { }
5207
5208 void work(int i) {
5209 ResourceMark rm;
5210 HandleMark hm;
5211
5212 G1ParScanThreadState pss(_g1h, i);
5213 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5214 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5215 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5216
5217 pss.set_evac_closure(&scan_evac_cl);
5218 pss.set_evac_failure_closure(&evac_failure_cl);
5219 pss.set_partial_scan_closure(&partial_scan_cl);
5220
5221 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5222
5223
5224 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5225 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5226
5227 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5228 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5229
5230 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5231 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5232
5233 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5234 // We also need to mark copied objects.
5235 copy_non_heap_cl = ©_mark_non_heap_cl;
5236 copy_perm_cl = ©_mark_perm_cl;
5237 }
5238
5239 // Is alive closure
5240 G1AlwaysAliveClosure always_alive(_g1h);
5241
5242 // Copying keep alive closure. Applied to referent objects that need
5243 // to be copied.
5244 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5245
5246 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5247
5248 int limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5249 int stride = MIN2(MAX2(_n_workers, 1), limit);
5250
5251 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5252 // So this must be true - but assert just in case someone decides to
5253 // change the worker ids.
5254 assert(0 <= i && i < limit, "sanity");
5255 assert(!rp->discovery_is_atomic(), "check this code");
5256
5257 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5258 for (int idx = i; idx < limit; idx += stride) {
5259 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5260
5261 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5262 while (iter.has_next()) {
5263 // Since discovery is not atomic for the CM ref processor, we
5264 // can see some null referent objects.
5265 iter.load_ptrs(DEBUG_ONLY(true));
5266 oop ref = iter.obj();
5267
5268 // This will filter nulls.
5269 if (iter.is_referent_alive()) {
5270 iter.make_referent_alive();
5271 }
5272 iter.move_to_next();
5273 }
5274 }
5275
5276 // Drain the queue - which may cause stealing
5277 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5278 drain_queue.do_void();
5279 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5280 assert(pss.refs()->is_empty(), "should be");
5281 }
5282 };
5283
5284 // Weak Reference processing during an evacuation pause (part 1).
5285 void G1CollectedHeap::process_discovered_references() {
5286 double ref_proc_start = os::elapsedTime();
5287
5288 ReferenceProcessor* rp = _ref_processor_stw;
5289 assert(rp->discovery_enabled(), "should have been enabled");
5290
5291 // Any reference objects, in the collection set, that were 'discovered'
5292 // by the CM ref processor should have already been copied (either by
5293 // applying the external root copy closure to the discovered lists, or
5294 // by following an RSet entry).
5295 //
5296 // But some of the referents, that are in the collection set, that these
5297 // reference objects point to may not have been copied: the STW ref
5298 // processor would have seen that the reference object had already
5299 // been 'discovered' and would have skipped discovering the reference,
5300 // but would not have treated the reference object as a regular oop.
5301 // As a reult the copy closure would not have been applied to the
5302 // referent object.
5303 //
5304 // We need to explicitly copy these referent objects - the references
5305 // will be processed at the end of remarking.
5306 //
5307 // We also need to do this copying before we process the reference
5308 // objects discovered by the STW ref processor in case one of these
5309 // referents points to another object which is also referenced by an
5310 // object discovered by the STW ref processor.
5311
5312 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5313 workers()->active_workers() : 1);
5314
5315 assert(active_workers == workers()->active_workers(),
5316 "Need to reset active_workers");
5317 set_par_threads(active_workers);
5318 G1ParPreserveCMReferentsTask keep_cm_referents(this, active_workers, _task_queues);
5319
5320 if (G1CollectedHeap::use_parallel_gc_threads()) {
5321 workers()->run_task(&keep_cm_referents);
5322 } else {
5323 keep_cm_referents.work(0);
5324 }
5325
5326 set_par_threads(0);
5327
5328 // Closure to test whether a referent is alive.
5329 G1STWIsAliveClosure is_alive(this);
5330
5331 // Even when parallel reference processing is enabled, the processing
5332 // of JNI refs is serial and performed serially by the current thread
5333 // rather than by a worker. The following PSS will be used for processing
5334 // JNI refs.
5335
5336 // Use only a single queue for this PSS.
5337 G1ParScanThreadState pss(this, 0);
5338
5339 // We do not embed a reference processor in the copying/scanning
5340 // closures while we're actually processing the discovered
5341 // reference objects.
5342 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5343 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5344 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5345
5346 pss.set_evac_closure(&scan_evac_cl);
5347 pss.set_evac_failure_closure(&evac_failure_cl);
5348 pss.set_partial_scan_closure(&partial_scan_cl);
5349
5350 assert(pss.refs()->is_empty(), "pre-condition");
5351
5352 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5353 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL);
5354
5355 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5356 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL);
5357
5358 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5359 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5360
5361 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5362 // We also need to mark copied objects.
5363 copy_non_heap_cl = ©_mark_non_heap_cl;
5364 copy_perm_cl = ©_mark_perm_cl;
5365 }
5366
5367 // Keep alive closure.
5368 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5369
5370 // Serial Complete GC closure
5371 G1STWDrainQueueClosure drain_queue(this, &pss);
5372
5373 // Setup the soft refs policy...
5374 rp->setup_policy(false);
5375
5376 if (!rp->processing_is_mt()) {
5377 // Serial reference processing...
5378 rp->process_discovered_references(&is_alive,
5379 &keep_alive,
5380 &drain_queue,
5381 NULL);
5382 } else {
5383 // Parallel reference processing
5384 assert(rp->num_q() == active_workers, "sanity");
5385 assert(active_workers <= rp->max_num_q(), "sanity");
5386
5387 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5388 rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5389 }
5390
5391 // We have completed copying any necessary live referent objects
5392 // (that were not copied during the actual pause) so we can
5393 // retire any active alloc buffers
5394 pss.retire_alloc_buffers();
5395 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5396
5397 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5398 g1_policy()->record_ref_proc_time(ref_proc_time * 1000.0);
5399 }
5400
5401 // Weak Reference processing during an evacuation pause (part 2).
5402 void G1CollectedHeap::enqueue_discovered_references() {
5403 double ref_enq_start = os::elapsedTime();
5404
5405 ReferenceProcessor* rp = _ref_processor_stw;
5406 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5407
5408 // Now enqueue any remaining on the discovered lists on to
5409 // the pending list.
5410 if (!rp->processing_is_mt()) {
5411 // Serial reference processing...
5412 rp->enqueue_discovered_references();
5413 } else {
5414 // Parallel reference enqueuing
5415
5416 int active_workers = (ParallelGCThreads > 0 ? workers()->active_workers() : 1);
5417 assert(active_workers == workers()->active_workers(),
5418 "Need to reset active_workers");
5419 assert(rp->num_q() == active_workers, "sanity");
5420 assert(active_workers <= rp->max_num_q(), "sanity");
5421
5422 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5423 rp->enqueue_discovered_references(&par_task_executor);
5424 }
5425
5426 rp->verify_no_references_recorded();
5427 assert(!rp->discovery_enabled(), "should have been disabled");
5428
5429 // FIXME
5430 // CM's reference processing also cleans up the string and symbol tables.
5431 // Should we do that here also? We could, but it is a serial operation
5432 // and could signicantly increase the pause time.
5433
5434 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5435 g1_policy()->record_ref_enq_time(ref_enq_time * 1000.0);
5436 }
5437
5438 void G1CollectedHeap::evacuate_collection_set() {
5439 set_evacuation_failed(false);
5440
5441 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5442 concurrent_g1_refine()->set_use_cache(false);
5443 concurrent_g1_refine()->clear_hot_cache_claimed_index();
5444
5445 int n_workers;
5446 if (G1CollectedHeap::use_parallel_gc_threads()) {
5447 n_workers =
5448 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5449 workers()->active_workers(),
5450 Threads::number_of_non_daemon_threads());
5451 assert(UseDynamicNumberOfGCThreads ||
5452 n_workers == workers()->total_workers(),
5453 "If not dynamic should be using all the workers");
5454 set_par_threads(n_workers);
5455 } else {
5456 assert(n_par_threads() == 0,
5457 "Should be the original non-parallel value");
5458 n_workers = 1;
5459 }
5460 workers()->set_active_workers(n_workers);
5461
5462 G1ParTask g1_par_task(this, _task_queues);
5463
5464 init_for_evac_failure(NULL);
5465
5466 rem_set()->prepare_for_younger_refs_iterate(true);
5467
5468 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5469 double start_par = os::elapsedTime();
5470
5471 if (G1CollectedHeap::use_parallel_gc_threads()) {
5472 // The individual threads will set their evac-failure closures.
5473 StrongRootsScope srs(this);
5474 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5475 // These tasks use ShareHeap::_process_strong_tasks
5476 assert(UseDynamicNumberOfGCThreads ||
5477 workers()->active_workers() == workers()->total_workers(),
5478 "If not dynamic should be using all the workers");
5479 workers()->run_task(&g1_par_task);
5480 } else {
5481 StrongRootsScope srs(this);
5482 g1_par_task.work(0);
5483 }
5484
5485 double par_time = (os::elapsedTime() - start_par) * 1000.0;
5486 g1_policy()->record_par_time(par_time);
5487
5488 set_par_threads(0);
5489
5490 // Process any discovered reference objects - we have
5491 // to do this _before_ we retire the GC alloc regions
5492 // as we may have to copy some 'reachable' referent
5493 // objects (and their reachable sub-graphs) that were
5494 // not copied during the pause.
5495 process_discovered_references();
5496
5497 // Weak root processing.
5498 // Note: when JSR 292 is enabled and code blobs can contain
5499 // non-perm oops then we will need to process the code blobs
5500 // here too.
5501 {
5502 G1STWIsAliveClosure is_alive(this);
5503 G1KeepAliveClosure keep_alive(this);
5504 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5505 }
5506
5507 release_gc_alloc_regions();
5508 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5509
5510 concurrent_g1_refine()->clear_hot_cache();
5511 concurrent_g1_refine()->set_use_cache(true);
5512
5513 finalize_for_evac_failure();
5514
5515 // Must do this before clearing the per-region evac-failure flags
5516 // (which is currently done when we free the collection set).
5517 // We also only do this if marking is actually in progress and so
5518 // have to do this before we set the mark_in_progress flag at the
5519 // end of an initial mark pause.
5520 concurrent_mark()->complete_marking_in_collection_set();
5521
5522 if (evacuation_failed()) {
5523 remove_self_forwarding_pointers();
5524 if (PrintGCDetails) {
5525 gclog_or_tty->print(" (to-space overflow)");
5526 } else if (PrintGC) {
5527 gclog_or_tty->print("--");
5528 }
5529 }
5530
5531 // Enqueue any remaining references remaining on the STW
5532 // reference processor's discovered lists. We need to do
5533 // this after the card table is cleaned (and verified) as
5534 // the act of enqueuing entries on to the pending list
5535 // will log these updates (and dirty their associated
5536 // cards). We need these updates logged to update any
5537 // RSets.
5538 enqueue_discovered_references();
5539
5540 if (G1DeferredRSUpdate) {
5541 RedirtyLoggedCardTableEntryFastClosure redirty;
5542 dirty_card_queue_set().set_closure(&redirty);
5543 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5544
5545 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5546 dcq.merge_bufferlists(&dirty_card_queue_set());
5547 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5548 }
5549 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5550 }
5551
5552 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5553 size_t* pre_used,
5554 FreeRegionList* free_list,
5555 OldRegionSet* old_proxy_set,
5556 HumongousRegionSet* humongous_proxy_set,
5557 HRRSCleanupTask* hrrs_cleanup_task,
5558 bool par) {
5559 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5560 if (hr->isHumongous()) {
5561 assert(hr->startsHumongous(), "we should only see starts humongous");
5562 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5563 } else {
5564 _old_set.remove_with_proxy(hr, old_proxy_set);
5565 free_region(hr, pre_used, free_list, par);
5566 }
5567 } else {
5568 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5569 }
5570 }
5571
5572 void G1CollectedHeap::free_region(HeapRegion* hr,
5573 size_t* pre_used,
5574 FreeRegionList* free_list,
5575 bool par) {
5576 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5577 assert(!hr->is_empty(), "the region should not be empty");
5578 assert(free_list != NULL, "pre-condition");
5579
5580 *pre_used += hr->used();
5581 hr->hr_clear(par, true /* clear_space */);
5582 free_list->add_as_head(hr);
5583 }
5584
5585 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5586 size_t* pre_used,
5587 FreeRegionList* free_list,
5588 HumongousRegionSet* humongous_proxy_set,
5589 bool par) {
5590 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5591 assert(free_list != NULL, "pre-condition");
5592 assert(humongous_proxy_set != NULL, "pre-condition");
5593
5594 size_t hr_used = hr->used();
5595 size_t hr_capacity = hr->capacity();
5596 size_t hr_pre_used = 0;
5597 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5598 hr->set_notHumongous();
5599 free_region(hr, &hr_pre_used, free_list, par);
5600
5601 size_t i = hr->hrs_index() + 1;
5602 size_t num = 1;
5603 while (i < n_regions()) {
5604 HeapRegion* curr_hr = region_at(i);
5605 if (!curr_hr->continuesHumongous()) {
5606 break;
5607 }
5608 curr_hr->set_notHumongous();
5609 free_region(curr_hr, &hr_pre_used, free_list, par);
5610 num += 1;
5611 i += 1;
5612 }
5613 assert(hr_pre_used == hr_used,
5614 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5615 "should be the same", hr_pre_used, hr_used));
5616 *pre_used += hr_pre_used;
5617 }
5618
5619 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5620 FreeRegionList* free_list,
5621 OldRegionSet* old_proxy_set,
5622 HumongousRegionSet* humongous_proxy_set,
5623 bool par) {
5624 if (pre_used > 0) {
5625 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5626 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5627 assert(_summary_bytes_used >= pre_used,
5628 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5629 "should be >= pre_used: "SIZE_FORMAT,
5630 _summary_bytes_used, pre_used));
5631 _summary_bytes_used -= pre_used;
5632 }
5633 if (free_list != NULL && !free_list->is_empty()) {
5634 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5635 _free_list.add_as_head(free_list);
5636 }
5637 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5638 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5639 _old_set.update_from_proxy(old_proxy_set);
5640 }
5641 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5642 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5643 _humongous_set.update_from_proxy(humongous_proxy_set);
5644 }
5645 }
5646
5647 class G1ParCleanupCTTask : public AbstractGangTask {
5648 CardTableModRefBS* _ct_bs;
5649 G1CollectedHeap* _g1h;
5650 HeapRegion* volatile _su_head;
5651 public:
5652 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5653 G1CollectedHeap* g1h) :
5654 AbstractGangTask("G1 Par Cleanup CT Task"),
5655 _ct_bs(ct_bs), _g1h(g1h) { }
5656
5657 void work(int i) {
5658 HeapRegion* r;
5659 while (r = _g1h->pop_dirty_cards_region()) {
5660 clear_cards(r);
5661 }
5662 }
5663
5664 void clear_cards(HeapRegion* r) {
5665 // Cards of the survivors should have already been dirtied.
5666 if (!r->is_survivor()) {
5667 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5668 }
5669 }
5670 };
5671
5672 #ifndef PRODUCT
5673 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5674 G1CollectedHeap* _g1h;
5675 CardTableModRefBS* _ct_bs;
5676 public:
5677 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5678 : _g1h(g1h), _ct_bs(ct_bs) { }
5679 virtual bool doHeapRegion(HeapRegion* r) {
5680 if (r->is_survivor()) {
5681 _g1h->verify_dirty_region(r);
5682 } else {
5683 _g1h->verify_not_dirty_region(r);
5684 }
5685 return false;
5686 }
5687 };
5688
5689 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5690 // All of the region should be clean.
5691 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5692 MemRegion mr(hr->bottom(), hr->end());
5693 ct_bs->verify_not_dirty_region(mr);
5694 }
5695
5696 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5697 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5698 // dirty allocated blocks as they allocate them. The thread that
5699 // retires each region and replaces it with a new one will do a
5700 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5701 // not dirty that area (one less thing to have to do while holding
5702 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5703 // is dirty.
5704 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5705 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5706 ct_bs->verify_dirty_region(mr);
5707 }
5708
5709 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5710 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5711 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5712 verify_dirty_region(hr);
5713 }
5714 }
5715
5716 void G1CollectedHeap::verify_dirty_young_regions() {
5717 verify_dirty_young_list(_young_list->first_region());
5718 verify_dirty_young_list(_young_list->first_survivor_region());
5719 }
5720 #endif
5721
5722 void G1CollectedHeap::cleanUpCardTable() {
5723 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5724 double start = os::elapsedTime();
5725
5726 {
5727 // Iterate over the dirty cards region list.
5728 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5729
5730 if (ParallelGCThreads > 0) {
5731 set_par_threads(workers()->total_workers());
5732 workers()->run_task(&cleanup_task);
5733 set_par_threads(0);
5734 } else {
5735 while (_dirty_cards_region_list) {
5736 HeapRegion* r = _dirty_cards_region_list;
5737 cleanup_task.clear_cards(r);
5738 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5739 if (_dirty_cards_region_list == r) {
5740 // The last region.
5741 _dirty_cards_region_list = NULL;
5742 }
5743 r->set_next_dirty_cards_region(NULL);
5744 }
5745 }
5746 #ifndef PRODUCT
5747 if (G1VerifyCTCleanup || VerifyAfterGC) {
5748 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5749 heap_region_iterate(&cleanup_verifier);
5750 }
5751 #endif
5752 }
5753
5754 double elapsed = os::elapsedTime() - start;
5755 g1_policy()->record_clear_ct_time(elapsed * 1000.0);
5756 }
5757
5758 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5759 size_t pre_used = 0;
5760 FreeRegionList local_free_list("Local List for CSet Freeing");
5761
5762 double young_time_ms = 0.0;
5763 double non_young_time_ms = 0.0;
5764
5765 // Since the collection set is a superset of the the young list,
5766 // all we need to do to clear the young list is clear its
5767 // head and length, and unlink any young regions in the code below
5768 _young_list->clear();
5769
5770 G1CollectorPolicy* policy = g1_policy();
5771
5772 double start_sec = os::elapsedTime();
5773 bool non_young = true;
5774
5775 HeapRegion* cur = cs_head;
5776 int age_bound = -1;
5777 size_t rs_lengths = 0;
5778
5779 while (cur != NULL) {
5780 assert(!is_on_master_free_list(cur), "sanity");
5781 if (non_young) {
5782 if (cur->is_young()) {
5783 double end_sec = os::elapsedTime();
5784 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5785 non_young_time_ms += elapsed_ms;
5786
5787 start_sec = os::elapsedTime();
5788 non_young = false;
5789 }
5790 } else {
5791 if (!cur->is_young()) {
5792 double end_sec = os::elapsedTime();
5793 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5794 young_time_ms += elapsed_ms;
5795
5796 start_sec = os::elapsedTime();
5797 non_young = true;
5798 }
5799 }
5800
5801 rs_lengths += cur->rem_set()->occupied();
5802
5803 HeapRegion* next = cur->next_in_collection_set();
5804 assert(cur->in_collection_set(), "bad CS");
5805 cur->set_next_in_collection_set(NULL);
5806 cur->set_in_collection_set(false);
5807
5808 if (cur->is_young()) {
5809 int index = cur->young_index_in_cset();
5810 assert(index != -1, "invariant");
5811 assert((size_t) index < policy->young_cset_region_length(), "invariant");
5812 size_t words_survived = _surviving_young_words[index];
5813 cur->record_surv_words_in_group(words_survived);
5814
5815 // At this point the we have 'popped' cur from the collection set
5816 // (linked via next_in_collection_set()) but it is still in the
5817 // young list (linked via next_young_region()). Clear the
5818 // _next_young_region field.
5819 cur->set_next_young_region(NULL);
5820 } else {
5821 int index = cur->young_index_in_cset();
5822 assert(index == -1, "invariant");
5823 }
5824
5825 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5826 (!cur->is_young() && cur->young_index_in_cset() == -1),
5827 "invariant" );
5828
5829 if (!cur->evacuation_failed()) {
5830 MemRegion used_mr = cur->used_region();
5831
5832 // And the region is empty.
5833 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5834
5835 // If marking is in progress then clear any objects marked in
5836 // the current region. Note mark_in_progress() returns false,
5837 // even during an initial mark pause, until the set_marking_started()
5838 // call which takes place later in the pause.
5839 if (mark_in_progress()) {
5840 assert(!g1_policy()->during_initial_mark_pause(), "sanity");
5841 _cm->nextMarkBitMap()->clearRange(used_mr);
5842 }
5843
5844 free_region(cur, &pre_used, &local_free_list, false /* par */);
5845 } else {
5846 cur->uninstall_surv_rate_group();
5847 if (cur->is_young()) {
5848 cur->set_young_index_in_cset(-1);
5849 }
5850 cur->set_not_young();
5851 cur->set_evacuation_failed(false);
5852 // The region is now considered to be old.
5853 _old_set.add(cur);
5854 }
5855 cur = next;
5856 }
5857
5858 policy->record_max_rs_lengths(rs_lengths);
5859 policy->cset_regions_freed();
5860
5861 double end_sec = os::elapsedTime();
5862 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5863
5864 if (non_young) {
5865 non_young_time_ms += elapsed_ms;
5866 } else {
5867 young_time_ms += elapsed_ms;
5868 }
5869
5870 update_sets_after_freeing_regions(pre_used, &local_free_list,
5871 NULL /* old_proxy_set */,
5872 NULL /* humongous_proxy_set */,
5873 false /* par */);
5874 policy->record_young_free_cset_time_ms(young_time_ms);
5875 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5876 }
5877
5878 // This routine is similar to the above but does not record
5879 // any policy statistics or update free lists; we are abandoning
5880 // the current incremental collection set in preparation of a
5881 // full collection. After the full GC we will start to build up
5882 // the incremental collection set again.
5883 // This is only called when we're doing a full collection
5884 // and is immediately followed by the tearing down of the young list.
5885
5886 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5887 HeapRegion* cur = cs_head;
5888
5889 while (cur != NULL) {
5890 HeapRegion* next = cur->next_in_collection_set();
5891 assert(cur->in_collection_set(), "bad CS");
5892 cur->set_next_in_collection_set(NULL);
5893 cur->set_in_collection_set(false);
5894 cur->set_young_index_in_cset(-1);
5895 cur = next;
5896 }
5897 }
5898
5899 void G1CollectedHeap::set_free_regions_coming() {
5900 if (G1ConcRegionFreeingVerbose) {
5901 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5902 "setting free regions coming");
5903 }
5904
5905 assert(!free_regions_coming(), "pre-condition");
5906 _free_regions_coming = true;
5907 }
5908
5909 void G1CollectedHeap::reset_free_regions_coming() {
5910 {
5911 assert(free_regions_coming(), "pre-condition");
5912 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5913 _free_regions_coming = false;
5914 SecondaryFreeList_lock->notify_all();
5915 }
5916
5917 if (G1ConcRegionFreeingVerbose) {
5918 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5919 "reset free regions coming");
5920 }
5921 }
5922
5923 void G1CollectedHeap::wait_while_free_regions_coming() {
5924 // Most of the time we won't have to wait, so let's do a quick test
5925 // first before we take the lock.
5926 if (!free_regions_coming()) {
5927 return;
5928 }
5929
5930 if (G1ConcRegionFreeingVerbose) {
5931 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5932 "waiting for free regions");
5933 }
5934
5935 {
5936 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5937 while (free_regions_coming()) {
5938 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5939 }
5940 }
5941
5942 if (G1ConcRegionFreeingVerbose) {
5943 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5944 "done waiting for free regions");
5945 }
5946 }
5947
5948 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5949 assert(heap_lock_held_for_gc(),
5950 "the heap lock should already be held by or for this thread");
5951 _young_list->push_region(hr);
5952 }
5953
5954 class NoYoungRegionsClosure: public HeapRegionClosure {
5955 private:
5956 bool _success;
5957 public:
5958 NoYoungRegionsClosure() : _success(true) { }
5959 bool doHeapRegion(HeapRegion* r) {
5960 if (r->is_young()) {
5961 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5962 r->bottom(), r->end());
5963 _success = false;
5964 }
5965 return false;
5966 }
5967 bool success() { return _success; }
5968 };
5969
5970 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5971 bool ret = _young_list->check_list_empty(check_sample);
5972
5973 if (check_heap) {
5974 NoYoungRegionsClosure closure;
5975 heap_region_iterate(&closure);
5976 ret = ret && closure.success();
5977 }
5978
5979 return ret;
5980 }
5981
5982 class TearDownRegionSetsClosure : public HeapRegionClosure {
5983 private:
5984 OldRegionSet *_old_set;
5985
5986 public:
5987 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
5988
5989 bool doHeapRegion(HeapRegion* r) {
5990 if (r->is_empty()) {
5991 // We ignore empty regions, we'll empty the free list afterwards
5992 } else if (r->is_young()) {
5993 // We ignore young regions, we'll empty the young list afterwards
5994 } else if (r->isHumongous()) {
5995 // We ignore humongous regions, we're not tearing down the
5996 // humongous region set
5997 } else {
5998 // The rest should be old
5999 _old_set->remove(r);
6000 }
6001 return false;
6002 }
6003
6004 ~TearDownRegionSetsClosure() {
6005 assert(_old_set->is_empty(), "post-condition");
6006 }
6007 };
6008
6009 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6010 assert_at_safepoint(true /* should_be_vm_thread */);
6011
6012 if (!free_list_only) {
6013 TearDownRegionSetsClosure cl(&_old_set);
6014 heap_region_iterate(&cl);
6015
6016 // Need to do this after the heap iteration to be able to
6017 // recognize the young regions and ignore them during the iteration.
6018 _young_list->empty_list();
6019 }
6020 _free_list.remove_all();
6021 }
6022
6023 class RebuildRegionSetsClosure : public HeapRegionClosure {
6024 private:
6025 bool _free_list_only;
6026 OldRegionSet* _old_set;
6027 FreeRegionList* _free_list;
6028 size_t _total_used;
6029
6030 public:
6031 RebuildRegionSetsClosure(bool free_list_only,
6032 OldRegionSet* old_set, FreeRegionList* free_list) :
6033 _free_list_only(free_list_only),
6034 _old_set(old_set), _free_list(free_list), _total_used(0) {
6035 assert(_free_list->is_empty(), "pre-condition");
6036 if (!free_list_only) {
6037 assert(_old_set->is_empty(), "pre-condition");
6038 }
6039 }
6040
6041 bool doHeapRegion(HeapRegion* r) {
6042 if (r->continuesHumongous()) {
6043 return false;
6044 }
6045
6046 if (r->is_empty()) {
6047 // Add free regions to the free list
6048 _free_list->add_as_tail(r);
6049 } else if (!_free_list_only) {
6050 assert(!r->is_young(), "we should not come across young regions");
6051
6052 if (r->isHumongous()) {
6053 // We ignore humongous regions, we left the humongous set unchanged
6054 } else {
6055 // The rest should be old, add them to the old set
6056 _old_set->add(r);
6057 }
6058 _total_used += r->used();
6059 }
6060
6061 return false;
6062 }
6063
6064 size_t total_used() {
6065 return _total_used;
6066 }
6067 };
6068
6069 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6070 assert_at_safepoint(true /* should_be_vm_thread */);
6071
6072 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6073 heap_region_iterate(&cl);
6074
6075 if (!free_list_only) {
6076 _summary_bytes_used = cl.total_used();
6077 }
6078 assert(_summary_bytes_used == recalculate_used(),
6079 err_msg("inconsistent _summary_bytes_used, "
6080 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6081 _summary_bytes_used, recalculate_used()));
6082 }
6083
6084 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6085 _refine_cte_cl->set_concurrent(concurrent);
6086 }
6087
6088 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6089 HeapRegion* hr = heap_region_containing(p);
6090 if (hr == NULL) {
6091 return is_in_permanent(p);
6092 } else {
6093 return hr->is_in(p);
6094 }
6095 }
6096
6097 // Methods for the mutator alloc region
6098
6099 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6100 bool force) {
6101 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6102 assert(!force || g1_policy()->can_expand_young_list(),
6103 "if force is true we should be able to expand the young list");
6104 bool young_list_full = g1_policy()->is_young_list_full();
6105 if (force || !young_list_full) {
6106 HeapRegion* new_alloc_region = new_region(word_size,
6107 false /* do_expand */);
6108 if (new_alloc_region != NULL) {
6109 set_region_short_lived_locked(new_alloc_region);
6110 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6111 return new_alloc_region;
6112 }
6113 }
6114 return NULL;
6115 }
6116
6117 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6118 size_t allocated_bytes) {
6119 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6120 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6121
6122 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6123 _summary_bytes_used += allocated_bytes;
6124 _hr_printer.retire(alloc_region);
6125 // We update the eden sizes here, when the region is retired,
6126 // instead of when it's allocated, since this is the point that its
6127 // used space has been recored in _summary_bytes_used.
6128 g1mm()->update_eden_size();
6129 }
6130
6131 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6132 bool force) {
6133 return _g1h->new_mutator_alloc_region(word_size, force);
6134 }
6135
6136 void G1CollectedHeap::set_par_threads() {
6137 // Don't change the number of workers. Use the value previously set
6138 // in the workgroup.
6139 int n_workers = workers()->active_workers();
6140 assert(UseDynamicNumberOfGCThreads ||
6141 n_workers == workers()->total_workers(),
6142 "Otherwise should be using the total number of workers");
6143 if (n_workers == 0) {
6144 assert(false, "Should have been set in prior evacuation pause.");
6145 n_workers = ParallelGCThreads;
6146 workers()->set_active_workers(n_workers);
6147 }
6148 set_par_threads(n_workers);
6149 }
6150
6151 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6152 size_t allocated_bytes) {
6153 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6154 }
6155
6156 // Methods for the GC alloc regions
6157
6158 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6159 size_t count,
6160 GCAllocPurpose ap) {
6161 assert(FreeList_lock->owned_by_self(), "pre-condition");
6162
6163 if (count < g1_policy()->max_regions(ap)) {
6164 HeapRegion* new_alloc_region = new_region(word_size,
6165 true /* do_expand */);
6166 if (new_alloc_region != NULL) {
6167 // We really only need to do this for old regions given that we
6168 // should never scan survivors. But it doesn't hurt to do it
6169 // for survivors too.
6170 new_alloc_region->set_saved_mark();
6171 if (ap == GCAllocForSurvived) {
6172 new_alloc_region->set_survivor();
6173 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6174 } else {
6175 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6176 }
6177 return new_alloc_region;
6178 } else {
6179 g1_policy()->note_alloc_region_limit_reached(ap);
6180 }
6181 }
6182 return NULL;
6183 }
6184
6185 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6186 size_t allocated_bytes,
6187 GCAllocPurpose ap) {
6188 alloc_region->note_end_of_copying();
6189 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6190 if (ap == GCAllocForSurvived) {
6191 young_list()->add_survivor_region(alloc_region);
6192 } else {
6193 _old_set.add(alloc_region);
6194 }
6195 _hr_printer.retire(alloc_region);
6196 }
6197
6198 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6199 bool force) {
6200 assert(!force, "not supported for GC alloc regions");
6201 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6202 }
6203
6204 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6205 size_t allocated_bytes) {
6206 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6207 GCAllocForSurvived);
6208 }
6209
6210 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6211 bool force) {
6212 assert(!force, "not supported for GC alloc regions");
6213 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6214 }
6215
6216 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6217 size_t allocated_bytes) {
6218 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6219 GCAllocForTenured);
6220 }
6221 // Heap region set verification
6222
6223 class VerifyRegionListsClosure : public HeapRegionClosure {
6224 private:
6225 FreeRegionList* _free_list;
6226 OldRegionSet* _old_set;
6227 HumongousRegionSet* _humongous_set;
6228 size_t _region_count;
6229
6230 public:
6231 VerifyRegionListsClosure(OldRegionSet* old_set,
6232 HumongousRegionSet* humongous_set,
6233 FreeRegionList* free_list) :
6234 _old_set(old_set), _humongous_set(humongous_set),
6235 _free_list(free_list), _region_count(0) { }
6236
6237 size_t region_count() { return _region_count; }
6238
6239 bool doHeapRegion(HeapRegion* hr) {
6240 _region_count += 1;
6241
6242 if (hr->continuesHumongous()) {
6243 return false;
6244 }
6245
6246 if (hr->is_young()) {
6247 // TODO
6248 } else if (hr->startsHumongous()) {
6249 _humongous_set->verify_next_region(hr);
6250 } else if (hr->is_empty()) {
6251 _free_list->verify_next_region(hr);
6252 } else {
6253 _old_set->verify_next_region(hr);
6254 }
6255 return false;
6256 }
6257 };
6258
6259 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index,
6260 HeapWord* bottom) {
6261 HeapWord* end = bottom + HeapRegion::GrainWords;
6262 MemRegion mr(bottom, end);
6263 assert(_g1_reserved.contains(mr), "invariant");
6264 // This might return NULL if the allocation fails
6265 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6266 }
6267
6268 void G1CollectedHeap::verify_region_sets() {
6269 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6270
6271 // First, check the explicit lists.
6272 _free_list.verify();
6273 {
6274 // Given that a concurrent operation might be adding regions to
6275 // the secondary free list we have to take the lock before
6276 // verifying it.
6277 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6278 _secondary_free_list.verify();
6279 }
6280 _old_set.verify();
6281 _humongous_set.verify();
6282
6283 // If a concurrent region freeing operation is in progress it will
6284 // be difficult to correctly attributed any free regions we come
6285 // across to the correct free list given that they might belong to
6286 // one of several (free_list, secondary_free_list, any local lists,
6287 // etc.). So, if that's the case we will skip the rest of the
6288 // verification operation. Alternatively, waiting for the concurrent
6289 // operation to complete will have a non-trivial effect on the GC's
6290 // operation (no concurrent operation will last longer than the
6291 // interval between two calls to verification) and it might hide
6292 // any issues that we would like to catch during testing.
6293 if (free_regions_coming()) {
6294 return;
6295 }
6296
6297 // Make sure we append the secondary_free_list on the free_list so
6298 // that all free regions we will come across can be safely
6299 // attributed to the free_list.
6300 append_secondary_free_list_if_not_empty_with_lock();
6301
6302 // Finally, make sure that the region accounting in the lists is
6303 // consistent with what we see in the heap.
6304 _old_set.verify_start();
6305 _humongous_set.verify_start();
6306 _free_list.verify_start();
6307
6308 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6309 heap_region_iterate(&cl);
6310
6311 _old_set.verify_end();
6312 _humongous_set.verify_end();
6313 _free_list.verify_end();
6314 }