1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1YCTypes.hpp"
43 #include "gc_implementation/g1/heapRegion.inline.hpp"
44 #include "gc_implementation/g1/heapRegionRemSet.hpp"
45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
46 #include "gc_implementation/g1/vm_operations_g1.hpp"
47 #include "gc_implementation/shared/gcHeapSummary.hpp"
48 #include "gc_implementation/shared/gcTimer.hpp"
49 #include "gc_implementation/shared/gcTrace.hpp"
50 #include "gc_implementation/shared/gcTraceTime.hpp"
51 #include "gc_implementation/shared/isGCActiveMark.hpp"
52 #include "memory/gcLocker.inline.hpp"
53 #include "memory/generationSpec.hpp"
54 #include "memory/iterator.hpp"
55 #include "memory/referenceProcessor.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/oop.pcgc.inline.hpp"
58 #include "runtime/vmThread.hpp"
59 #include "utilities/ticks.hpp"
60
61 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
62
63 // turn it on so that the contents of the young list (scan-only /
64 // to-be-collected) are printed at "strategic" points before / during
65 // / after the collection --- this is useful for debugging
66 #define YOUNG_LIST_VERBOSE 0
67 // CURRENT STATUS
68 // This file is under construction. Search for "FIXME".
69
70 // INVARIANTS/NOTES
71 //
72 // All allocation activity covered by the G1CollectedHeap interface is
73 // serialized by acquiring the HeapLock. This happens in mem_allocate
74 // and allocate_new_tlab, which are the "entry" points to the
75 // allocation code from the rest of the JVM. (Note that this does not
76 // apply to TLAB allocation, which is not part of this interface: it
77 // is done by clients of this interface.)
78
79 // Notes on implementation of parallelism in different tasks.
80 //
81 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
82 // The number of GC workers is passed to heap_region_par_iterate_chunked().
83 // It does use run_task() which sets _n_workers in the task.
84 // G1ParTask executes g1_process_strong_roots() ->
85 // SharedHeap::process_strong_roots() which calls eventually to
86 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
87 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
88 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
89 //
90
91 // Local to this file.
92
93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
94 SuspendibleThreadSet* _sts;
95 G1RemSet* _g1rs;
96 ConcurrentG1Refine* _cg1r;
97 bool _concurrent;
98 public:
99 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
100 G1RemSet* g1rs,
101 ConcurrentG1Refine* cg1r) :
102 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
103 {}
104 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
105 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
106 // This path is executed by the concurrent refine or mutator threads,
107 // concurrently, and so we do not care if card_ptr contains references
108 // that point into the collection set.
109 assert(!oops_into_cset, "should be");
110
111 if (_concurrent && _sts->should_yield()) {
112 // Caller will actually yield.
113 return false;
114 }
115 // Otherwise, we finished successfully; return true.
116 return true;
117 }
118 void set_concurrent(bool b) { _concurrent = b; }
119 };
120
121
122 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
123 int _calls;
124 G1CollectedHeap* _g1h;
125 CardTableModRefBS* _ctbs;
126 int _histo[256];
127 public:
128 ClearLoggedCardTableEntryClosure() :
129 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
130 {
131 for (int i = 0; i < 256; i++) _histo[i] = 0;
132 }
133 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
134 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
135 _calls++;
136 unsigned char* ujb = (unsigned char*)card_ptr;
137 int ind = (int)(*ujb);
138 _histo[ind]++;
139 *card_ptr = -1;
140 }
141 return true;
142 }
143 int calls() { return _calls; }
144 void print_histo() {
145 gclog_or_tty->print_cr("Card table value histogram:");
146 for (int i = 0; i < 256; i++) {
147 if (_histo[i] != 0) {
148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
149 }
150 }
151 }
152 };
153
154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
155 int _calls;
156 G1CollectedHeap* _g1h;
157 CardTableModRefBS* _ctbs;
158 public:
159 RedirtyLoggedCardTableEntryClosure() :
160 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
161
162 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
163 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
164 _calls++;
165 *card_ptr = 0;
166 }
167 return true;
168 }
169 int calls() { return _calls; }
170 };
171
172 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
173 public:
174 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
175 *card_ptr = CardTableModRefBS::dirty_card_val();
176 return true;
177 }
178 };
179
180 YoungList::YoungList(G1CollectedHeap* g1h) :
181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
183 guarantee(check_list_empty(false), "just making sure...");
184 }
185
186 void YoungList::push_region(HeapRegion *hr) {
187 assert(!hr->is_young(), "should not already be young");
188 assert(hr->get_next_young_region() == NULL, "cause it should!");
189
190 hr->set_next_young_region(_head);
191 _head = hr;
192
193 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
194 ++_length;
195 }
196
197 void YoungList::add_survivor_region(HeapRegion* hr) {
198 assert(hr->is_survivor(), "should be flagged as survivor region");
199 assert(hr->get_next_young_region() == NULL, "cause it should!");
200
201 hr->set_next_young_region(_survivor_head);
202 if (_survivor_head == NULL) {
203 _survivor_tail = hr;
204 }
205 _survivor_head = hr;
206 ++_survivor_length;
207 }
208
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 list->set_not_young();
215 list = next;
216 }
217 }
218
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
221
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
225
226 empty_list(_survivor_head);
227 _survivor_head = NULL;
228 _survivor_tail = NULL;
229 _survivor_length = 0;
230
231 _last_sampled_rs_lengths = 0;
232
233 assert(check_list_empty(false), "just making sure...");
234 }
235
236 bool YoungList::check_list_well_formed() {
237 bool ret = true;
238
239 uint length = 0;
240 HeapRegion* curr = _head;
241 HeapRegion* last = NULL;
242 while (curr != NULL) {
243 if (!curr->is_young()) {
244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
245 "incorrectly tagged (y: %d, surv: %d)",
246 curr->bottom(), curr->end(),
247 curr->is_young(), curr->is_survivor());
248 ret = false;
249 }
250 ++length;
251 last = curr;
252 curr = curr->get_next_young_region();
253 }
254 ret = ret && (length == _length);
255
256 if (!ret) {
257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
258 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
259 length, _length);
260 }
261
262 return ret;
263 }
264
265 bool YoungList::check_list_empty(bool check_sample) {
266 bool ret = true;
267
268 if (_length != 0) {
269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
270 _length);
271 ret = false;
272 }
273 if (check_sample && _last_sampled_rs_lengths != 0) {
274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
275 ret = false;
276 }
277 if (_head != NULL) {
278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
279 ret = false;
280 }
281 if (!ret) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
283 }
284
285 return ret;
286 }
287
288 void
289 YoungList::rs_length_sampling_init() {
290 _sampled_rs_lengths = 0;
291 _curr = _head;
292 }
293
294 bool
295 YoungList::rs_length_sampling_more() {
296 return _curr != NULL;
297 }
298
299 void
300 YoungList::rs_length_sampling_next() {
301 assert( _curr != NULL, "invariant" );
302 size_t rs_length = _curr->rem_set()->occupied();
303
304 _sampled_rs_lengths += rs_length;
305
306 // The current region may not yet have been added to the
307 // incremental collection set (it gets added when it is
308 // retired as the current allocation region).
309 if (_curr->in_collection_set()) {
310 // Update the collection set policy information for this region
311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
312 }
313
314 _curr = _curr->get_next_young_region();
315 if (_curr == NULL) {
316 _last_sampled_rs_lengths = _sampled_rs_lengths;
317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
318 }
319 }
320
321 void
322 YoungList::reset_auxilary_lists() {
323 guarantee( is_empty(), "young list should be empty" );
324 assert(check_list_well_formed(), "young list should be well formed");
325
326 // Add survivor regions to SurvRateGroup.
327 _g1h->g1_policy()->note_start_adding_survivor_regions();
328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
329
330 int young_index_in_cset = 0;
331 for (HeapRegion* curr = _survivor_head;
332 curr != NULL;
333 curr = curr->get_next_young_region()) {
334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
335
336 // The region is a non-empty survivor so let's add it to
337 // the incremental collection set for the next evacuation
338 // pause.
339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
340 young_index_in_cset += 1;
341 }
342 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
343 _g1h->g1_policy()->note_stop_adding_survivor_regions();
344
345 _head = _survivor_head;
346 _length = _survivor_length;
347 if (_survivor_head != NULL) {
348 assert(_survivor_tail != NULL, "cause it shouldn't be");
349 assert(_survivor_length > 0, "invariant");
350 _survivor_tail->set_next_young_region(NULL);
351 }
352
353 // Don't clear the survivor list handles until the start of
354 // the next evacuation pause - we need it in order to re-tag
355 // the survivor regions from this evacuation pause as 'young'
356 // at the start of the next.
357
358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
359
360 assert(check_list_well_formed(), "young list should be well formed");
361 }
362
363 void YoungList::print() {
364 HeapRegion* lists[] = {_head, _survivor_head};
365 const char* names[] = {"YOUNG", "SURVIVOR"};
366
367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
369 HeapRegion *curr = lists[list];
370 if (curr == NULL)
371 gclog_or_tty->print_cr(" empty");
372 while (curr != NULL) {
373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
374 HR_FORMAT_PARAMS(curr),
375 curr->prev_top_at_mark_start(),
376 curr->next_top_at_mark_start(),
377 curr->age_in_surv_rate_group_cond());
378 curr = curr->get_next_young_region();
379 }
380 }
381
382 gclog_or_tty->print_cr("");
383 }
384
385 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
386 {
387 // Claim the right to put the region on the dirty cards region list
388 // by installing a self pointer.
389 HeapRegion* next = hr->get_next_dirty_cards_region();
390 if (next == NULL) {
391 HeapRegion* res = (HeapRegion*)
392 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
393 NULL);
394 if (res == NULL) {
395 HeapRegion* head;
396 do {
397 // Put the region to the dirty cards region list.
398 head = _dirty_cards_region_list;
399 next = (HeapRegion*)
400 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
401 if (next == head) {
402 assert(hr->get_next_dirty_cards_region() == hr,
403 "hr->get_next_dirty_cards_region() != hr");
404 if (next == NULL) {
405 // The last region in the list points to itself.
406 hr->set_next_dirty_cards_region(hr);
407 } else {
408 hr->set_next_dirty_cards_region(next);
409 }
410 }
411 } while (next != head);
412 }
413 }
414 }
415
416 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
417 {
418 HeapRegion* head;
419 HeapRegion* hr;
420 do {
421 head = _dirty_cards_region_list;
422 if (head == NULL) {
423 return NULL;
424 }
425 HeapRegion* new_head = head->get_next_dirty_cards_region();
426 if (head == new_head) {
427 // The last region.
428 new_head = NULL;
429 }
430 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
431 head);
432 } while (hr != head);
433 assert(hr != NULL, "invariant");
434 hr->set_next_dirty_cards_region(NULL);
435 return hr;
436 }
437
438 void G1CollectedHeap::stop_conc_gc_threads() {
439 _cg1r->stop();
440 _cmThread->stop();
441 }
442
443 #ifdef ASSERT
444 // A region is added to the collection set as it is retired
445 // so an address p can point to a region which will be in the
446 // collection set but has not yet been retired. This method
447 // therefore is only accurate during a GC pause after all
448 // regions have been retired. It is used for debugging
449 // to check if an nmethod has references to objects that can
450 // be move during a partial collection. Though it can be
451 // inaccurate, it is sufficient for G1 because the conservative
452 // implementation of is_scavengable() for G1 will indicate that
453 // all nmethods must be scanned during a partial collection.
454 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
455 HeapRegion* hr = heap_region_containing(p);
456 return hr != NULL && hr->in_collection_set();
457 }
458 #endif
459
460 // Returns true if the reference points to an object that
461 // can move in an incremental collection.
462 bool G1CollectedHeap::is_scavengable(const void* p) {
463 G1CollectedHeap* g1h = G1CollectedHeap::heap();
464 G1CollectorPolicy* g1p = g1h->g1_policy();
465 HeapRegion* hr = heap_region_containing(p);
466 if (hr == NULL) {
467 // null
468 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
469 return false;
470 } else {
471 return !hr->isHumongous();
472 }
473 }
474
475 void G1CollectedHeap::check_ct_logs_at_safepoint() {
476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
477 CardTableModRefBS* ct_bs = g1_barrier_set();
478
479 // Count the dirty cards at the start.
480 CountNonCleanMemRegionClosure count1(this);
481 ct_bs->mod_card_iterate(&count1);
482 int orig_count = count1.n();
483
484 // First clear the logged cards.
485 ClearLoggedCardTableEntryClosure clear;
486 dcqs.set_closure(&clear);
487 dcqs.apply_closure_to_all_completed_buffers();
488 dcqs.iterate_closure_all_threads(false);
489 clear.print_histo();
490
491 // Now ensure that there's no dirty cards.
492 CountNonCleanMemRegionClosure count2(this);
493 ct_bs->mod_card_iterate(&count2);
494 if (count2.n() != 0) {
495 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
496 count2.n(), orig_count);
497 }
498 guarantee(count2.n() == 0, "Card table should be clean.");
499
500 RedirtyLoggedCardTableEntryClosure redirty;
501 JavaThread::dirty_card_queue_set().set_closure(&redirty);
502 dcqs.apply_closure_to_all_completed_buffers();
503 dcqs.iterate_closure_all_threads(false);
504 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
505 clear.calls(), orig_count);
506 guarantee(redirty.calls() == clear.calls(),
507 "Or else mechanism is broken.");
508
509 CountNonCleanMemRegionClosure count3(this);
510 ct_bs->mod_card_iterate(&count3);
511 if (count3.n() != orig_count) {
512 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
513 orig_count, count3.n());
514 guarantee(count3.n() >= orig_count, "Should have restored them all.");
515 }
516
517 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
518 }
519
520 // Private class members.
521
522 G1CollectedHeap* G1CollectedHeap::_g1h;
523
524 // Private methods.
525
526 HeapRegion*
527 G1CollectedHeap::new_region_try_secondary_free_list() {
528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
529 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
530 if (!_secondary_free_list.is_empty()) {
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "secondary_free_list has %u entries",
534 _secondary_free_list.length());
535 }
536 // It looks as if there are free regions available on the
537 // secondary_free_list. Let's move them to the free_list and try
538 // again to allocate from it.
539 append_secondary_free_list();
540
541 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
542 "empty we should have moved at least one entry to the free_list");
543 HeapRegion* res = _free_list.remove_head();
544 if (G1ConcRegionFreeingVerbose) {
545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
546 "allocated "HR_FORMAT" from secondary_free_list",
547 HR_FORMAT_PARAMS(res));
548 }
549 return res;
550 }
551
552 // Wait here until we get notified either when (a) there are no
553 // more free regions coming or (b) some regions have been moved on
554 // the secondary_free_list.
555 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
556 }
557
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "could not allocate from secondary_free_list");
561 }
562 return NULL;
563 }
564
565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
566 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
567 "the only time we use this to allocate a humongous region is "
568 "when we are allocating a single humongous region");
569
570 HeapRegion* res;
571 if (G1StressConcRegionFreeing) {
572 if (!_secondary_free_list.is_empty()) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "forced to look at the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list();
578 if (res != NULL) {
579 return res;
580 }
581 }
582 }
583 res = _free_list.remove_head_or_null();
584 if (res == NULL) {
585 if (G1ConcRegionFreeingVerbose) {
586 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
587 "res == NULL, trying the secondary_free_list");
588 }
589 res = new_region_try_secondary_free_list();
590 }
591 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
592 // Currently, only attempts to allocate GC alloc regions set
593 // do_expand to true. So, we should only reach here during a
594 // safepoint. If this assumption changes we might have to
595 // reconsider the use of _expand_heap_after_alloc_failure.
596 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
597
598 ergo_verbose1(ErgoHeapSizing,
599 "attempt heap expansion",
600 ergo_format_reason("region allocation request failed")
601 ergo_format_byte("allocation request"),
602 word_size * HeapWordSize);
603 if (expand(word_size * HeapWordSize)) {
604 // Given that expand() succeeded in expanding the heap, and we
605 // always expand the heap by an amount aligned to the heap
606 // region size, the free list should in theory not be empty. So
607 // it would probably be OK to use remove_head(). But the extra
608 // check for NULL is unlikely to be a performance issue here (we
609 // just expanded the heap!) so let's just be conservative and
610 // use remove_head_or_null().
611 res = _free_list.remove_head_or_null();
612 } else {
613 _expand_heap_after_alloc_failure = false;
614 }
615 }
616 return res;
617 }
618
619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
620 size_t word_size) {
621 assert(isHumongous(word_size), "word_size should be humongous");
622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
623
624 uint first = G1_NULL_HRS_INDEX;
625 if (num_regions == 1) {
626 // Only one region to allocate, no need to go through the slower
627 // path. The caller will attempt the expansion if this fails, so
628 // let's not try to expand here too.
629 HeapRegion* hr = new_region(word_size, false /* do_expand */);
630 if (hr != NULL) {
631 first = hr->hrs_index();
632 } else {
633 first = G1_NULL_HRS_INDEX;
634 }
635 } else {
636 // We can't allocate humongous regions while cleanupComplete() is
637 // running, since some of the regions we find to be empty might not
638 // yet be added to the free list and it is not straightforward to
639 // know which list they are on so that we can remove them. Note
640 // that we only need to do this if we need to allocate more than
641 // one region to satisfy the current humongous allocation
642 // request. If we are only allocating one region we use the common
643 // region allocation code (see above).
644 wait_while_free_regions_coming();
645 append_secondary_free_list_if_not_empty_with_lock();
646
647 if (free_regions() >= num_regions) {
648 first = _hrs.find_contiguous(num_regions);
649 if (first != G1_NULL_HRS_INDEX) {
650 for (uint i = first; i < first + num_regions; ++i) {
651 HeapRegion* hr = region_at(i);
652 assert(hr->is_empty(), "sanity");
653 assert(is_on_master_free_list(hr), "sanity");
654 hr->set_pending_removal(true);
655 }
656 _free_list.remove_all_pending(num_regions);
657 }
658 }
659 }
660 return first;
661 }
662
663 HeapWord*
664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
665 uint num_regions,
666 size_t word_size) {
667 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
668 assert(isHumongous(word_size), "word_size should be humongous");
669 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
670
671 // Index of last region in the series + 1.
672 uint last = first + num_regions;
673
674 // We need to initialize the region(s) we just discovered. This is
675 // a bit tricky given that it can happen concurrently with
676 // refinement threads refining cards on these regions and
677 // potentially wanting to refine the BOT as they are scanning
678 // those cards (this can happen shortly after a cleanup; see CR
679 // 6991377). So we have to set up the region(s) carefully and in
680 // a specific order.
681
682 // The word size sum of all the regions we will allocate.
683 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
684 assert(word_size <= word_size_sum, "sanity");
685
686 // This will be the "starts humongous" region.
687 HeapRegion* first_hr = region_at(first);
688 // The header of the new object will be placed at the bottom of
689 // the first region.
690 HeapWord* new_obj = first_hr->bottom();
691 // This will be the new end of the first region in the series that
692 // should also match the end of the last region in the series.
693 HeapWord* new_end = new_obj + word_size_sum;
694 // This will be the new top of the first region that will reflect
695 // this allocation.
696 HeapWord* new_top = new_obj + word_size;
697
698 // First, we need to zero the header of the space that we will be
699 // allocating. When we update top further down, some refinement
700 // threads might try to scan the region. By zeroing the header we
701 // ensure that any thread that will try to scan the region will
702 // come across the zero klass word and bail out.
703 //
704 // NOTE: It would not have been correct to have used
705 // CollectedHeap::fill_with_object() and make the space look like
706 // an int array. The thread that is doing the allocation will
707 // later update the object header to a potentially different array
708 // type and, for a very short period of time, the klass and length
709 // fields will be inconsistent. This could cause a refinement
710 // thread to calculate the object size incorrectly.
711 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
712
713 // We will set up the first region as "starts humongous". This
714 // will also update the BOT covering all the regions to reflect
715 // that there is a single object that starts at the bottom of the
716 // first region.
717 first_hr->set_startsHumongous(new_top, new_end);
718
719 // Then, if there are any, we will set up the "continues
720 // humongous" regions.
721 HeapRegion* hr = NULL;
722 for (uint i = first + 1; i < last; ++i) {
723 hr = region_at(i);
724 hr->set_continuesHumongous(first_hr);
725 }
726 // If we have "continues humongous" regions (hr != NULL), then the
727 // end of the last one should match new_end.
728 assert(hr == NULL || hr->end() == new_end, "sanity");
729
730 // Up to this point no concurrent thread would have been able to
731 // do any scanning on any region in this series. All the top
732 // fields still point to bottom, so the intersection between
733 // [bottom,top] and [card_start,card_end] will be empty. Before we
734 // update the top fields, we'll do a storestore to make sure that
735 // no thread sees the update to top before the zeroing of the
736 // object header and the BOT initialization.
737 OrderAccess::storestore();
738
739 // Now that the BOT and the object header have been initialized,
740 // we can update top of the "starts humongous" region.
741 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
742 "new_top should be in this region");
743 first_hr->set_top(new_top);
744 if (_hr_printer.is_active()) {
745 HeapWord* bottom = first_hr->bottom();
746 HeapWord* end = first_hr->orig_end();
747 if ((first + 1) == last) {
748 // the series has a single humongous region
749 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
750 } else {
751 // the series has more than one humongous regions
752 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
753 }
754 }
755
756 // Now, we will update the top fields of the "continues humongous"
757 // regions. The reason we need to do this is that, otherwise,
758 // these regions would look empty and this will confuse parts of
759 // G1. For example, the code that looks for a consecutive number
760 // of empty regions will consider them empty and try to
761 // re-allocate them. We can extend is_empty() to also include
762 // !continuesHumongous(), but it is easier to just update the top
763 // fields here. The way we set top for all regions (i.e., top ==
764 // end for all regions but the last one, top == new_top for the
765 // last one) is actually used when we will free up the humongous
766 // region in free_humongous_region().
767 hr = NULL;
768 for (uint i = first + 1; i < last; ++i) {
769 hr = region_at(i);
770 if ((i + 1) == last) {
771 // last continues humongous region
772 assert(hr->bottom() < new_top && new_top <= hr->end(),
773 "new_top should fall on this region");
774 hr->set_top(new_top);
775 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
776 } else {
777 // not last one
778 assert(new_top > hr->end(), "new_top should be above this region");
779 hr->set_top(hr->end());
780 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
781 }
782 }
783 // If we have continues humongous regions (hr != NULL), then the
784 // end of the last one should match new_end and its top should
785 // match new_top.
786 assert(hr == NULL ||
787 (hr->end() == new_end && hr->top() == new_top), "sanity");
788
789 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
790 _summary_bytes_used += first_hr->used();
791 _humongous_set.add(first_hr);
792
793 return new_obj;
794 }
795
796 // If could fit into free regions w/o expansion, try.
797 // Otherwise, if can expand, do so.
798 // Otherwise, if using ex regions might help, try with ex given back.
799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
800 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
801
802 verify_region_sets_optional();
803
804 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
805 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
806 uint x_num = expansion_regions();
807 uint fs = _hrs.free_suffix();
808 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
809 if (first == G1_NULL_HRS_INDEX) {
810 // The only thing we can do now is attempt expansion.
811 if (fs + x_num >= num_regions) {
812 // If the number of regions we're trying to allocate for this
813 // object is at most the number of regions in the free suffix,
814 // then the call to humongous_obj_allocate_find_first() above
815 // should have succeeded and we wouldn't be here.
816 //
817 // We should only be trying to expand when the free suffix is
818 // not sufficient for the object _and_ we have some expansion
819 // room available.
820 assert(num_regions > fs, "earlier allocation should have succeeded");
821
822 ergo_verbose1(ErgoHeapSizing,
823 "attempt heap expansion",
824 ergo_format_reason("humongous allocation request failed")
825 ergo_format_byte("allocation request"),
826 word_size * HeapWordSize);
827 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
828 // Even though the heap was expanded, it might not have
829 // reached the desired size. So, we cannot assume that the
830 // allocation will succeed.
831 first = humongous_obj_allocate_find_first(num_regions, word_size);
832 }
833 }
834 }
835
836 HeapWord* result = NULL;
837 if (first != G1_NULL_HRS_INDEX) {
838 result =
839 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
840 assert(result != NULL, "it should always return a valid result");
841
842 // A successful humongous object allocation changes the used space
843 // information of the old generation so we need to recalculate the
844 // sizes and update the jstat counters here.
845 g1mm()->update_sizes();
846 }
847
848 verify_region_sets_optional();
849
850 return result;
851 }
852
853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
856
857 unsigned int dummy_gc_count_before;
858 int dummy_gclocker_retry_count = 0;
859 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
860 }
861
862 HeapWord*
863 G1CollectedHeap::mem_allocate(size_t word_size,
864 bool* gc_overhead_limit_was_exceeded) {
865 assert_heap_not_locked_and_not_at_safepoint();
866
867 // Loop until the allocation is satisfied, or unsatisfied after GC.
868 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
869 unsigned int gc_count_before;
870
871 HeapWord* result = NULL;
872 if (!isHumongous(word_size)) {
873 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
874 } else {
875 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
876 }
877 if (result != NULL) {
878 return result;
879 }
880
881 // Create the garbage collection operation...
882 VM_G1CollectForAllocation op(gc_count_before, word_size);
883 // ...and get the VM thread to execute it.
884 VMThread::execute(&op);
885
886 if (op.prologue_succeeded() && op.pause_succeeded()) {
887 // If the operation was successful we'll return the result even
888 // if it is NULL. If the allocation attempt failed immediately
889 // after a Full GC, it's unlikely we'll be able to allocate now.
890 HeapWord* result = op.result();
891 if (result != NULL && !isHumongous(word_size)) {
892 // Allocations that take place on VM operations do not do any
893 // card dirtying and we have to do it here. We only have to do
894 // this for non-humongous allocations, though.
895 dirty_young_block(result, word_size);
896 }
897 return result;
898 } else {
899 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
900 return NULL;
901 }
902 assert(op.result() == NULL,
903 "the result should be NULL if the VM op did not succeed");
904 }
905
906 // Give a warning if we seem to be looping forever.
907 if ((QueuedAllocationWarningCount > 0) &&
908 (try_count % QueuedAllocationWarningCount == 0)) {
909 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
910 }
911 }
912
913 ShouldNotReachHere();
914 return NULL;
915 }
916
917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
918 unsigned int *gc_count_before_ret,
919 int* gclocker_retry_count_ret) {
920 // Make sure you read the note in attempt_allocation_humongous().
921
922 assert_heap_not_locked_and_not_at_safepoint();
923 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
924 "be called for humongous allocation requests");
925
926 // We should only get here after the first-level allocation attempt
927 // (attempt_allocation()) failed to allocate.
928
929 // We will loop until a) we manage to successfully perform the
930 // allocation or b) we successfully schedule a collection which
931 // fails to perform the allocation. b) is the only case when we'll
932 // return NULL.
933 HeapWord* result = NULL;
934 for (int try_count = 1; /* we'll return */; try_count += 1) {
935 bool should_try_gc;
936 unsigned int gc_count_before;
937
938 {
939 MutexLockerEx x(Heap_lock);
940
941 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
942 false /* bot_updates */);
943 if (result != NULL) {
944 return result;
945 }
946
947 // If we reach here, attempt_allocation_locked() above failed to
948 // allocate a new region. So the mutator alloc region should be NULL.
949 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
950
951 if (GC_locker::is_active_and_needs_gc()) {
952 if (g1_policy()->can_expand_young_list()) {
953 // No need for an ergo verbose message here,
954 // can_expand_young_list() does this when it returns true.
955 result = _mutator_alloc_region.attempt_allocation_force(word_size,
956 false /* bot_updates */);
957 if (result != NULL) {
958 return result;
959 }
960 }
961 should_try_gc = false;
962 } else {
963 // The GCLocker may not be active but the GCLocker initiated
964 // GC may not yet have been performed (GCLocker::needs_gc()
965 // returns true). In this case we do not try this GC and
966 // wait until the GCLocker initiated GC is performed, and
967 // then retry the allocation.
968 if (GC_locker::needs_gc()) {
969 should_try_gc = false;
970 } else {
971 // Read the GC count while still holding the Heap_lock.
972 gc_count_before = total_collections();
973 should_try_gc = true;
974 }
975 }
976 }
977
978 if (should_try_gc) {
979 bool succeeded;
980 result = do_collection_pause(word_size, gc_count_before, &succeeded,
981 GCCause::_g1_inc_collection_pause);
982 if (result != NULL) {
983 assert(succeeded, "only way to get back a non-NULL result");
984 return result;
985 }
986
987 if (succeeded) {
988 // If we get here we successfully scheduled a collection which
989 // failed to allocate. No point in trying to allocate
990 // further. We'll just return NULL.
991 MutexLockerEx x(Heap_lock);
992 *gc_count_before_ret = total_collections();
993 return NULL;
994 }
995 } else {
996 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
997 MutexLockerEx x(Heap_lock);
998 *gc_count_before_ret = total_collections();
999 return NULL;
1000 }
1001 // The GCLocker is either active or the GCLocker initiated
1002 // GC has not yet been performed. Stall until it is and
1003 // then retry the allocation.
1004 GC_locker::stall_until_clear();
1005 (*gclocker_retry_count_ret) += 1;
1006 }
1007
1008 // We can reach here if we were unsuccessful in scheduling a
1009 // collection (because another thread beat us to it) or if we were
1010 // stalled due to the GC locker. In either can we should retry the
1011 // allocation attempt in case another thread successfully
1012 // performed a collection and reclaimed enough space. We do the
1013 // first attempt (without holding the Heap_lock) here and the
1014 // follow-on attempt will be at the start of the next loop
1015 // iteration (after taking the Heap_lock).
1016 result = _mutator_alloc_region.attempt_allocation(word_size,
1017 false /* bot_updates */);
1018 if (result != NULL) {
1019 return result;
1020 }
1021
1022 // Give a warning if we seem to be looping forever.
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_slow() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1035 unsigned int * gc_count_before_ret,
1036 int* gclocker_retry_count_ret) {
1037 // The structure of this method has a lot of similarities to
1038 // attempt_allocation_slow(). The reason these two were not merged
1039 // into a single one is that such a method would require several "if
1040 // allocation is not humongous do this, otherwise do that"
1041 // conditional paths which would obscure its flow. In fact, an early
1042 // version of this code did use a unified method which was harder to
1043 // follow and, as a result, it had subtle bugs that were hard to
1044 // track down. So keeping these two methods separate allows each to
1045 // be more readable. It will be good to keep these two in sync as
1046 // much as possible.
1047
1048 assert_heap_not_locked_and_not_at_safepoint();
1049 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1050 "should only be called for humongous allocations");
1051
1052 // Humongous objects can exhaust the heap quickly, so we should check if we
1053 // need to start a marking cycle at each humongous object allocation. We do
1054 // the check before we do the actual allocation. The reason for doing it
1055 // before the allocation is that we avoid having to keep track of the newly
1056 // allocated memory while we do a GC.
1057 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1058 word_size)) {
1059 collect(GCCause::_g1_humongous_allocation);
1060 }
1061
1062 // We will loop until a) we manage to successfully perform the
1063 // allocation or b) we successfully schedule a collection which
1064 // fails to perform the allocation. b) is the only case when we'll
1065 // return NULL.
1066 HeapWord* result = NULL;
1067 for (int try_count = 1; /* we'll return */; try_count += 1) {
1068 bool should_try_gc;
1069 unsigned int gc_count_before;
1070
1071 {
1072 MutexLockerEx x(Heap_lock);
1073
1074 // Given that humongous objects are not allocated in young
1075 // regions, we'll first try to do the allocation without doing a
1076 // collection hoping that there's enough space in the heap.
1077 result = humongous_obj_allocate(word_size);
1078 if (result != NULL) {
1079 return result;
1080 }
1081
1082 if (GC_locker::is_active_and_needs_gc()) {
1083 should_try_gc = false;
1084 } else {
1085 // The GCLocker may not be active but the GCLocker initiated
1086 // GC may not yet have been performed (GCLocker::needs_gc()
1087 // returns true). In this case we do not try this GC and
1088 // wait until the GCLocker initiated GC is performed, and
1089 // then retry the allocation.
1090 if (GC_locker::needs_gc()) {
1091 should_try_gc = false;
1092 } else {
1093 // Read the GC count while still holding the Heap_lock.
1094 gc_count_before = total_collections();
1095 should_try_gc = true;
1096 }
1097 }
1098 }
1099
1100 if (should_try_gc) {
1101 // If we failed to allocate the humongous object, we should try to
1102 // do a collection pause (if we're allowed) in case it reclaims
1103 // enough space for the allocation to succeed after the pause.
1104
1105 bool succeeded;
1106 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1107 GCCause::_g1_humongous_allocation);
1108 if (result != NULL) {
1109 assert(succeeded, "only way to get back a non-NULL result");
1110 return result;
1111 }
1112
1113 if (succeeded) {
1114 // If we get here we successfully scheduled a collection which
1115 // failed to allocate. No point in trying to allocate
1116 // further. We'll just return NULL.
1117 MutexLockerEx x(Heap_lock);
1118 *gc_count_before_ret = total_collections();
1119 return NULL;
1120 }
1121 } else {
1122 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1123 MutexLockerEx x(Heap_lock);
1124 *gc_count_before_ret = total_collections();
1125 return NULL;
1126 }
1127 // The GCLocker is either active or the GCLocker initiated
1128 // GC has not yet been performed. Stall until it is and
1129 // then retry the allocation.
1130 GC_locker::stall_until_clear();
1131 (*gclocker_retry_count_ret) += 1;
1132 }
1133
1134 // We can reach here if we were unsuccessful in scheduling a
1135 // collection (because another thread beat us to it) or if we were
1136 // stalled due to the GC locker. In either can we should retry the
1137 // allocation attempt in case another thread successfully
1138 // performed a collection and reclaimed enough space. Give a
1139 // warning if we seem to be looping forever.
1140
1141 if ((QueuedAllocationWarningCount > 0) &&
1142 (try_count % QueuedAllocationWarningCount == 0)) {
1143 warning("G1CollectedHeap::attempt_allocation_humongous() "
1144 "retries %d times", try_count);
1145 }
1146 }
1147
1148 ShouldNotReachHere();
1149 return NULL;
1150 }
1151
1152 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1153 bool expect_null_mutator_alloc_region) {
1154 assert_at_safepoint(true /* should_be_vm_thread */);
1155 assert(_mutator_alloc_region.get() == NULL ||
1156 !expect_null_mutator_alloc_region,
1157 "the current alloc region was unexpectedly found to be non-NULL");
1158
1159 if (!isHumongous(word_size)) {
1160 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1161 false /* bot_updates */);
1162 } else {
1163 HeapWord* result = humongous_obj_allocate(word_size);
1164 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1165 g1_policy()->set_initiate_conc_mark_if_possible();
1166 }
1167 return result;
1168 }
1169
1170 ShouldNotReachHere();
1171 }
1172
1173 class PostMCRemSetClearClosure: public HeapRegionClosure {
1174 G1CollectedHeap* _g1h;
1175 ModRefBarrierSet* _mr_bs;
1176 public:
1177 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1178 _g1h(g1h), _mr_bs(mr_bs) {}
1179
1180 bool doHeapRegion(HeapRegion* r) {
1181 HeapRegionRemSet* hrrs = r->rem_set();
1182
1183 if (r->continuesHumongous()) {
1184 // We'll assert that the strong code root list and RSet is empty
1185 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1186 assert(hrrs->occupied() == 0, "RSet should be empty");
1187 return false;
1188 }
1189
1190 _g1h->reset_gc_time_stamps(r);
1191 hrrs->clear();
1192 // You might think here that we could clear just the cards
1193 // corresponding to the used region. But no: if we leave a dirty card
1194 // in a region we might allocate into, then it would prevent that card
1195 // from being enqueued, and cause it to be missed.
1196 // Re: the performance cost: we shouldn't be doing full GC anyway!
1197 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1198
1199 return false;
1200 }
1201 };
1202
1203 void G1CollectedHeap::clear_rsets_post_compaction() {
1204 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1205 heap_region_iterate(&rs_clear);
1206 }
1207
1208 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1209 G1CollectedHeap* _g1h;
1210 UpdateRSOopClosure _cl;
1211 int _worker_i;
1212 public:
1213 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1214 _cl(g1->g1_rem_set(), worker_i),
1215 _worker_i(worker_i),
1216 _g1h(g1)
1217 { }
1218
1219 bool doHeapRegion(HeapRegion* r) {
1220 if (!r->continuesHumongous()) {
1221 _cl.set_from(r);
1222 r->oop_iterate(&_cl);
1223 }
1224 return false;
1225 }
1226 };
1227
1228 class ParRebuildRSTask: public AbstractGangTask {
1229 G1CollectedHeap* _g1;
1230 public:
1231 ParRebuildRSTask(G1CollectedHeap* g1)
1232 : AbstractGangTask("ParRebuildRSTask"),
1233 _g1(g1)
1234 { }
1235
1236 void work(uint worker_id) {
1237 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1238 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1239 _g1->workers()->active_workers(),
1240 HeapRegion::RebuildRSClaimValue);
1241 }
1242 };
1243
1244 class PostCompactionPrinterClosure: public HeapRegionClosure {
1245 private:
1246 G1HRPrinter* _hr_printer;
1247 public:
1248 bool doHeapRegion(HeapRegion* hr) {
1249 assert(!hr->is_young(), "not expecting to find young regions");
1250 // We only generate output for non-empty regions.
1251 if (!hr->is_empty()) {
1252 if (!hr->isHumongous()) {
1253 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1254 } else if (hr->startsHumongous()) {
1255 if (hr->region_num() == 1) {
1256 // single humongous region
1257 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1258 } else {
1259 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1260 }
1261 } else {
1262 assert(hr->continuesHumongous(), "only way to get here");
1263 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1264 }
1265 }
1266 return false;
1267 }
1268
1269 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1270 : _hr_printer(hr_printer) { }
1271 };
1272
1273 void G1CollectedHeap::print_hrs_post_compaction() {
1274 PostCompactionPrinterClosure cl(hr_printer());
1275 heap_region_iterate(&cl);
1276 }
1277
1278 bool G1CollectedHeap::do_collection(bool explicit_gc,
1279 bool clear_all_soft_refs,
1280 size_t word_size) {
1281 assert_at_safepoint(true /* should_be_vm_thread */);
1282
1283 if (GC_locker::check_active_before_gc()) {
1284 return false;
1285 }
1286
1287 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1288 gc_timer->register_gc_start();
1289
1290 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1291 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1292
1293 SvcGCMarker sgcm(SvcGCMarker::FULL);
1294 ResourceMark rm;
1295
1296 print_heap_before_gc();
1297 trace_heap_before_gc(gc_tracer);
1298
1299 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1300
1301 HRSPhaseSetter x(HRSPhaseFullGC);
1302 verify_region_sets_optional();
1303
1304 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1305 collector_policy()->should_clear_all_soft_refs();
1306
1307 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1308
1309 {
1310 IsGCActiveMark x;
1311
1312 // Timing
1313 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1314 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1315 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1316
1317 {
1318 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1319 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1320 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1321
1322 double start = os::elapsedTime();
1323 g1_policy()->record_full_collection_start();
1324
1325 // Note: When we have a more flexible GC logging framework that
1326 // allows us to add optional attributes to a GC log record we
1327 // could consider timing and reporting how long we wait in the
1328 // following two methods.
1329 wait_while_free_regions_coming();
1330 // If we start the compaction before the CM threads finish
1331 // scanning the root regions we might trip them over as we'll
1332 // be moving objects / updating references. So let's wait until
1333 // they are done. By telling them to abort, they should complete
1334 // early.
1335 _cm->root_regions()->abort();
1336 _cm->root_regions()->wait_until_scan_finished();
1337 append_secondary_free_list_if_not_empty_with_lock();
1338
1339 gc_prologue(true);
1340 increment_total_collections(true /* full gc */);
1341 increment_old_marking_cycles_started();
1342
1343 assert(used() == recalculate_used(), "Should be equal");
1344
1345 verify_before_gc();
1346
1347 pre_full_gc_dump(gc_timer);
1348
1349 COMPILER2_PRESENT(DerivedPointerTable::clear());
1350
1351 // Disable discovery and empty the discovered lists
1352 // for the CM ref processor.
1353 ref_processor_cm()->disable_discovery();
1354 ref_processor_cm()->abandon_partial_discovery();
1355 ref_processor_cm()->verify_no_references_recorded();
1356
1357 // Abandon current iterations of concurrent marking and concurrent
1358 // refinement, if any are in progress. We have to do this before
1359 // wait_until_scan_finished() below.
1360 concurrent_mark()->abort();
1361
1362 // Make sure we'll choose a new allocation region afterwards.
1363 release_mutator_alloc_region();
1364 abandon_gc_alloc_regions();
1365 g1_rem_set()->cleanupHRRS();
1366
1367 // We should call this after we retire any currently active alloc
1368 // regions so that all the ALLOC / RETIRE events are generated
1369 // before the start GC event.
1370 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1371
1372 // We may have added regions to the current incremental collection
1373 // set between the last GC or pause and now. We need to clear the
1374 // incremental collection set and then start rebuilding it afresh
1375 // after this full GC.
1376 abandon_collection_set(g1_policy()->inc_cset_head());
1377 g1_policy()->clear_incremental_cset();
1378 g1_policy()->stop_incremental_cset_building();
1379
1380 tear_down_region_sets(false /* free_list_only */);
1381 g1_policy()->set_gcs_are_young(true);
1382
1383 // See the comments in g1CollectedHeap.hpp and
1384 // G1CollectedHeap::ref_processing_init() about
1385 // how reference processing currently works in G1.
1386
1387 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1388 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1389
1390 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1391 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1392
1393 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1394 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1395
1396 // Do collection work
1397 {
1398 HandleMark hm; // Discard invalid handles created during gc
1399 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1400 }
1401
1402 assert(free_regions() == 0, "we should not have added any free regions");
1403 rebuild_region_sets(false /* free_list_only */);
1404
1405 // Enqueue any discovered reference objects that have
1406 // not been removed from the discovered lists.
1407 ref_processor_stw()->enqueue_discovered_references();
1408
1409 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1410
1411 MemoryService::track_memory_usage();
1412
1413 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1414 ref_processor_stw()->verify_no_references_recorded();
1415
1416 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1417 ClassLoaderDataGraph::purge();
1418 MetaspaceAux::verify_metrics();
1419
1420 // Note: since we've just done a full GC, concurrent
1421 // marking is no longer active. Therefore we need not
1422 // re-enable reference discovery for the CM ref processor.
1423 // That will be done at the start of the next marking cycle.
1424 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1425 ref_processor_cm()->verify_no_references_recorded();
1426
1427 reset_gc_time_stamp();
1428 // Since everything potentially moved, we will clear all remembered
1429 // sets, and clear all cards. Later we will rebuild remembered
1430 // sets. We will also reset the GC time stamps of the regions.
1431 clear_rsets_post_compaction();
1432 check_gc_time_stamps();
1433
1434 // Resize the heap if necessary.
1435 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1436
1437 if (_hr_printer.is_active()) {
1438 // We should do this after we potentially resize the heap so
1439 // that all the COMMIT / UNCOMMIT events are generated before
1440 // the end GC event.
1441
1442 print_hrs_post_compaction();
1443 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1444 }
1445
1446 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1447 if (hot_card_cache->use_cache()) {
1448 hot_card_cache->reset_card_counts();
1449 hot_card_cache->reset_hot_cache();
1450 }
1451
1452 // Rebuild remembered sets of all regions.
1453 if (G1CollectedHeap::use_parallel_gc_threads()) {
1454 uint n_workers =
1455 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1456 workers()->active_workers(),
1457 Threads::number_of_non_daemon_threads());
1458 assert(UseDynamicNumberOfGCThreads ||
1459 n_workers == workers()->total_workers(),
1460 "If not dynamic should be using all the workers");
1461 workers()->set_active_workers(n_workers);
1462 // Set parallel threads in the heap (_n_par_threads) only
1463 // before a parallel phase and always reset it to 0 after
1464 // the phase so that the number of parallel threads does
1465 // no get carried forward to a serial phase where there
1466 // may be code that is "possibly_parallel".
1467 set_par_threads(n_workers);
1468
1469 ParRebuildRSTask rebuild_rs_task(this);
1470 assert(check_heap_region_claim_values(
1471 HeapRegion::InitialClaimValue), "sanity check");
1472 assert(UseDynamicNumberOfGCThreads ||
1473 workers()->active_workers() == workers()->total_workers(),
1474 "Unless dynamic should use total workers");
1475 // Use the most recent number of active workers
1476 assert(workers()->active_workers() > 0,
1477 "Active workers not properly set");
1478 set_par_threads(workers()->active_workers());
1479 workers()->run_task(&rebuild_rs_task);
1480 set_par_threads(0);
1481 assert(check_heap_region_claim_values(
1482 HeapRegion::RebuildRSClaimValue), "sanity check");
1483 reset_heap_region_claim_values();
1484 } else {
1485 RebuildRSOutOfRegionClosure rebuild_rs(this);
1486 heap_region_iterate(&rebuild_rs);
1487 }
1488
1489 // Rebuild the strong code root lists for each region
1490 rebuild_strong_code_roots();
1491
1492 if (true) { // FIXME
1493 MetaspaceGC::compute_new_size();
1494 }
1495
1496 #ifdef TRACESPINNING
1497 ParallelTaskTerminator::print_termination_counts();
1498 #endif
1499
1500 // Discard all rset updates
1501 JavaThread::dirty_card_queue_set().abandon_logs();
1502 assert(!G1DeferredRSUpdate
1503 || (G1DeferredRSUpdate &&
1504 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1505
1506 _young_list->reset_sampled_info();
1507 // At this point there should be no regions in the
1508 // entire heap tagged as young.
1509 assert(check_young_list_empty(true /* check_heap */),
1510 "young list should be empty at this point");
1511
1512 // Update the number of full collections that have been completed.
1513 increment_old_marking_cycles_completed(false /* concurrent */);
1514
1515 _hrs.verify_optional();
1516 verify_region_sets_optional();
1517
1518 verify_after_gc();
1519
1520 // Start a new incremental collection set for the next pause
1521 assert(g1_policy()->collection_set() == NULL, "must be");
1522 g1_policy()->start_incremental_cset_building();
1523
1524 // Clear the _cset_fast_test bitmap in anticipation of adding
1525 // regions to the incremental collection set for the next
1526 // evacuation pause.
1527 clear_cset_fast_test();
1528
1529 init_mutator_alloc_region();
1530
1531 double end = os::elapsedTime();
1532 g1_policy()->record_full_collection_end();
1533
1534 if (G1Log::fine()) {
1535 g1_policy()->print_heap_transition();
1536 }
1537
1538 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1539 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1540 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1541 // before any GC notifications are raised.
1542 g1mm()->update_sizes();
1543
1544 gc_epilogue(true);
1545 }
1546
1547 if (G1Log::finer()) {
1548 g1_policy()->print_detailed_heap_transition(true /* full */);
1549 }
1550
1551 print_heap_after_gc();
1552 trace_heap_after_gc(gc_tracer);
1553
1554 post_full_gc_dump(gc_timer);
1555
1556 gc_timer->register_gc_end();
1557 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1558 }
1559
1560 return true;
1561 }
1562
1563 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1564 // do_collection() will return whether it succeeded in performing
1565 // the GC. Currently, there is no facility on the
1566 // do_full_collection() API to notify the caller than the collection
1567 // did not succeed (e.g., because it was locked out by the GC
1568 // locker). So, right now, we'll ignore the return value.
1569 bool dummy = do_collection(true, /* explicit_gc */
1570 clear_all_soft_refs,
1571 0 /* word_size */);
1572 }
1573
1574 // This code is mostly copied from TenuredGeneration.
1575 void
1576 G1CollectedHeap::
1577 resize_if_necessary_after_full_collection(size_t word_size) {
1578 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1579
1580 // Include the current allocation, if any, and bytes that will be
1581 // pre-allocated to support collections, as "used".
1582 const size_t used_after_gc = used();
1583 const size_t capacity_after_gc = capacity();
1584 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1585
1586 // This is enforced in arguments.cpp.
1587 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1588 "otherwise the code below doesn't make sense");
1589
1590 // We don't have floating point command-line arguments
1591 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1592 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1593 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1594 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1595
1596 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1597 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1598
1599 // We have to be careful here as these two calculations can overflow
1600 // 32-bit size_t's.
1601 double used_after_gc_d = (double) used_after_gc;
1602 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1603 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1604
1605 // Let's make sure that they are both under the max heap size, which
1606 // by default will make them fit into a size_t.
1607 double desired_capacity_upper_bound = (double) max_heap_size;
1608 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1609 desired_capacity_upper_bound);
1610 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1611 desired_capacity_upper_bound);
1612
1613 // We can now safely turn them into size_t's.
1614 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1615 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1616
1617 // This assert only makes sense here, before we adjust them
1618 // with respect to the min and max heap size.
1619 assert(minimum_desired_capacity <= maximum_desired_capacity,
1620 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1621 "maximum_desired_capacity = "SIZE_FORMAT,
1622 minimum_desired_capacity, maximum_desired_capacity));
1623
1624 // Should not be greater than the heap max size. No need to adjust
1625 // it with respect to the heap min size as it's a lower bound (i.e.,
1626 // we'll try to make the capacity larger than it, not smaller).
1627 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1628 // Should not be less than the heap min size. No need to adjust it
1629 // with respect to the heap max size as it's an upper bound (i.e.,
1630 // we'll try to make the capacity smaller than it, not greater).
1631 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1632
1633 if (capacity_after_gc < minimum_desired_capacity) {
1634 // Don't expand unless it's significant
1635 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1636 ergo_verbose4(ErgoHeapSizing,
1637 "attempt heap expansion",
1638 ergo_format_reason("capacity lower than "
1639 "min desired capacity after Full GC")
1640 ergo_format_byte("capacity")
1641 ergo_format_byte("occupancy")
1642 ergo_format_byte_perc("min desired capacity"),
1643 capacity_after_gc, used_after_gc,
1644 minimum_desired_capacity, (double) MinHeapFreeRatio);
1645 expand(expand_bytes);
1646
1647 // No expansion, now see if we want to shrink
1648 } else if (capacity_after_gc > maximum_desired_capacity) {
1649 // Capacity too large, compute shrinking size
1650 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1651 ergo_verbose4(ErgoHeapSizing,
1652 "attempt heap shrinking",
1653 ergo_format_reason("capacity higher than "
1654 "max desired capacity after Full GC")
1655 ergo_format_byte("capacity")
1656 ergo_format_byte("occupancy")
1657 ergo_format_byte_perc("max desired capacity"),
1658 capacity_after_gc, used_after_gc,
1659 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1660 shrink(shrink_bytes);
1661 }
1662 }
1663
1664
1665 HeapWord*
1666 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1667 bool* succeeded) {
1668 assert_at_safepoint(true /* should_be_vm_thread */);
1669
1670 *succeeded = true;
1671 // Let's attempt the allocation first.
1672 HeapWord* result =
1673 attempt_allocation_at_safepoint(word_size,
1674 false /* expect_null_mutator_alloc_region */);
1675 if (result != NULL) {
1676 assert(*succeeded, "sanity");
1677 return result;
1678 }
1679
1680 // In a G1 heap, we're supposed to keep allocation from failing by
1681 // incremental pauses. Therefore, at least for now, we'll favor
1682 // expansion over collection. (This might change in the future if we can
1683 // do something smarter than full collection to satisfy a failed alloc.)
1684 result = expand_and_allocate(word_size);
1685 if (result != NULL) {
1686 assert(*succeeded, "sanity");
1687 return result;
1688 }
1689
1690 // Expansion didn't work, we'll try to do a Full GC.
1691 bool gc_succeeded = do_collection(false, /* explicit_gc */
1692 false, /* clear_all_soft_refs */
1693 word_size);
1694 if (!gc_succeeded) {
1695 *succeeded = false;
1696 return NULL;
1697 }
1698
1699 // Retry the allocation
1700 result = attempt_allocation_at_safepoint(word_size,
1701 true /* expect_null_mutator_alloc_region */);
1702 if (result != NULL) {
1703 assert(*succeeded, "sanity");
1704 return result;
1705 }
1706
1707 // Then, try a Full GC that will collect all soft references.
1708 gc_succeeded = do_collection(false, /* explicit_gc */
1709 true, /* clear_all_soft_refs */
1710 word_size);
1711 if (!gc_succeeded) {
1712 *succeeded = false;
1713 return NULL;
1714 }
1715
1716 // Retry the allocation once more
1717 result = attempt_allocation_at_safepoint(word_size,
1718 true /* expect_null_mutator_alloc_region */);
1719 if (result != NULL) {
1720 assert(*succeeded, "sanity");
1721 return result;
1722 }
1723
1724 assert(!collector_policy()->should_clear_all_soft_refs(),
1725 "Flag should have been handled and cleared prior to this point");
1726
1727 // What else? We might try synchronous finalization later. If the total
1728 // space available is large enough for the allocation, then a more
1729 // complete compaction phase than we've tried so far might be
1730 // appropriate.
1731 assert(*succeeded, "sanity");
1732 return NULL;
1733 }
1734
1735 // Attempting to expand the heap sufficiently
1736 // to support an allocation of the given "word_size". If
1737 // successful, perform the allocation and return the address of the
1738 // allocated block, or else "NULL".
1739
1740 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1741 assert_at_safepoint(true /* should_be_vm_thread */);
1742
1743 verify_region_sets_optional();
1744
1745 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1746 ergo_verbose1(ErgoHeapSizing,
1747 "attempt heap expansion",
1748 ergo_format_reason("allocation request failed")
1749 ergo_format_byte("allocation request"),
1750 word_size * HeapWordSize);
1751 if (expand(expand_bytes)) {
1752 _hrs.verify_optional();
1753 verify_region_sets_optional();
1754 return attempt_allocation_at_safepoint(word_size,
1755 false /* expect_null_mutator_alloc_region */);
1756 }
1757 return NULL;
1758 }
1759
1760 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1761 HeapWord* new_end) {
1762 assert(old_end != new_end, "don't call this otherwise");
1763 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1764
1765 // Update the committed mem region.
1766 _g1_committed.set_end(new_end);
1767 // Tell the card table about the update.
1768 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1769 // Tell the BOT about the update.
1770 _bot_shared->resize(_g1_committed.word_size());
1771 // Tell the hot card cache about the update
1772 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1773 }
1774
1775 bool G1CollectedHeap::expand(size_t expand_bytes) {
1776 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1777 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1778 HeapRegion::GrainBytes);
1779 ergo_verbose2(ErgoHeapSizing,
1780 "expand the heap",
1781 ergo_format_byte("requested expansion amount")
1782 ergo_format_byte("attempted expansion amount"),
1783 expand_bytes, aligned_expand_bytes);
1784
1785 if (_g1_storage.uncommitted_size() == 0) {
1786 ergo_verbose0(ErgoHeapSizing,
1787 "did not expand the heap",
1788 ergo_format_reason("heap already fully expanded"));
1789 return false;
1790 }
1791
1792 // First commit the memory.
1793 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1794 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1795 if (successful) {
1796 // Then propagate this update to the necessary data structures.
1797 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1798 update_committed_space(old_end, new_end);
1799
1800 FreeRegionList expansion_list("Local Expansion List");
1801 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1802 assert(mr.start() == old_end, "post-condition");
1803 // mr might be a smaller region than what was requested if
1804 // expand_by() was unable to allocate the HeapRegion instances
1805 assert(mr.end() <= new_end, "post-condition");
1806
1807 size_t actual_expand_bytes = mr.byte_size();
1808 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1809 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1810 "post-condition");
1811 if (actual_expand_bytes < aligned_expand_bytes) {
1812 // We could not expand _hrs to the desired size. In this case we
1813 // need to shrink the committed space accordingly.
1814 assert(mr.end() < new_end, "invariant");
1815
1816 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1817 // First uncommit the memory.
1818 _g1_storage.shrink_by(diff_bytes);
1819 // Then propagate this update to the necessary data structures.
1820 update_committed_space(new_end, mr.end());
1821 }
1822 _free_list.add_as_tail(&expansion_list);
1823
1824 if (_hr_printer.is_active()) {
1825 HeapWord* curr = mr.start();
1826 while (curr < mr.end()) {
1827 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1828 _hr_printer.commit(curr, curr_end);
1829 curr = curr_end;
1830 }
1831 assert(curr == mr.end(), "post-condition");
1832 }
1833 g1_policy()->record_new_heap_size(n_regions());
1834 } else {
1835 ergo_verbose0(ErgoHeapSizing,
1836 "did not expand the heap",
1837 ergo_format_reason("heap expansion operation failed"));
1838 // The expansion of the virtual storage space was unsuccessful.
1839 // Let's see if it was because we ran out of swap.
1840 if (G1ExitOnExpansionFailure &&
1841 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1842 // We had head room...
1843 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1844 }
1845 }
1846 return successful;
1847 }
1848
1849 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1850 size_t aligned_shrink_bytes =
1851 ReservedSpace::page_align_size_down(shrink_bytes);
1852 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1853 HeapRegion::GrainBytes);
1854 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1855
1856 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1857 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1858 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1859
1860 ergo_verbose3(ErgoHeapSizing,
1861 "shrink the heap",
1862 ergo_format_byte("requested shrinking amount")
1863 ergo_format_byte("aligned shrinking amount")
1864 ergo_format_byte("attempted shrinking amount"),
1865 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1866 if (num_regions_removed > 0) {
1867 _g1_storage.shrink_by(shrunk_bytes);
1868 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1869
1870 if (_hr_printer.is_active()) {
1871 HeapWord* curr = old_end;
1872 while (curr > new_end) {
1873 HeapWord* curr_end = curr;
1874 curr -= HeapRegion::GrainWords;
1875 _hr_printer.uncommit(curr, curr_end);
1876 }
1877 }
1878
1879 _expansion_regions += num_regions_removed;
1880 update_committed_space(old_end, new_end);
1881 HeapRegionRemSet::shrink_heap(n_regions());
1882 g1_policy()->record_new_heap_size(n_regions());
1883 } else {
1884 ergo_verbose0(ErgoHeapSizing,
1885 "did not shrink the heap",
1886 ergo_format_reason("heap shrinking operation failed"));
1887 }
1888 }
1889
1890 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1891 verify_region_sets_optional();
1892
1893 // We should only reach here at the end of a Full GC which means we
1894 // should not not be holding to any GC alloc regions. The method
1895 // below will make sure of that and do any remaining clean up.
1896 abandon_gc_alloc_regions();
1897
1898 // Instead of tearing down / rebuilding the free lists here, we
1899 // could instead use the remove_all_pending() method on free_list to
1900 // remove only the ones that we need to remove.
1901 tear_down_region_sets(true /* free_list_only */);
1902 shrink_helper(shrink_bytes);
1903 rebuild_region_sets(true /* free_list_only */);
1904
1905 _hrs.verify_optional();
1906 verify_region_sets_optional();
1907 }
1908
1909 // Public methods.
1910
1911 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1912 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1913 #endif // _MSC_VER
1914
1915
1916 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1917 SharedHeap(policy_),
1918 _g1_policy(policy_),
1919 _dirty_card_queue_set(false),
1920 _into_cset_dirty_card_queue_set(false),
1921 _is_alive_closure_cm(this),
1922 _is_alive_closure_stw(this),
1923 _ref_processor_cm(NULL),
1924 _ref_processor_stw(NULL),
1925 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1926 _bot_shared(NULL),
1927 _evac_failure_scan_stack(NULL),
1928 _mark_in_progress(false),
1929 _cg1r(NULL), _summary_bytes_used(0),
1930 _g1mm(NULL),
1931 _refine_cte_cl(NULL),
1932 _full_collection(false),
1933 _free_list("Master Free List"),
1934 _secondary_free_list("Secondary Free List"),
1935 _old_set("Old Set"),
1936 _humongous_set("Master Humongous Set"),
1937 _free_regions_coming(false),
1938 _young_list(new YoungList(this)),
1939 _gc_time_stamp(0),
1940 _retained_old_gc_alloc_region(NULL),
1941 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1942 _old_plab_stats(OldPLABSize, PLABWeight),
1943 _expand_heap_after_alloc_failure(true),
1944 _surviving_young_words(NULL),
1945 _old_marking_cycles_started(0),
1946 _old_marking_cycles_completed(0),
1947 _concurrent_cycle_started(false),
1948 _in_cset_fast_test(NULL),
1949 _in_cset_fast_test_base(NULL),
1950 _dirty_cards_region_list(NULL),
1951 _worker_cset_start_region(NULL),
1952 _worker_cset_start_region_time_stamp(NULL),
1953 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1954 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1955 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1956 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1957
1958 _g1h = this;
1959 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1960 vm_exit_during_initialization("Failed necessary allocation.");
1961 }
1962
1963 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1964
1965 int n_queues = MAX2((int)ParallelGCThreads, 1);
1966 _task_queues = new RefToScanQueueSet(n_queues);
1967
1968 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1969 assert(n_rem_sets > 0, "Invariant.");
1970
1971 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1972 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1973 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1974
1975 for (int i = 0; i < n_queues; i++) {
1976 RefToScanQueue* q = new RefToScanQueue();
1977 q->initialize();
1978 _task_queues->register_queue(i, q);
1979 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1980 }
1981 clear_cset_start_regions();
1982
1983 // Initialize the G1EvacuationFailureALot counters and flags.
1984 NOT_PRODUCT(reset_evacuation_should_fail();)
1985
1986 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1987 }
1988
1989 jint G1CollectedHeap::initialize() {
1990 CollectedHeap::pre_initialize();
1991 os::enable_vtime();
1992
1993 G1Log::init();
1994
1995 // Necessary to satisfy locking discipline assertions.
1996
1997 MutexLocker x(Heap_lock);
1998
1999 // We have to initialize the printer before committing the heap, as
2000 // it will be used then.
2001 _hr_printer.set_active(G1PrintHeapRegions);
2002
2003 // While there are no constraints in the GC code that HeapWordSize
2004 // be any particular value, there are multiple other areas in the
2005 // system which believe this to be true (e.g. oop->object_size in some
2006 // cases incorrectly returns the size in wordSize units rather than
2007 // HeapWordSize).
2008 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2009
2010 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2011 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2012 size_t heap_alignment = collector_policy()->heap_alignment();
2013
2014 // Ensure that the sizes are properly aligned.
2015 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2016 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2017 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2018
2019 _cg1r = new ConcurrentG1Refine(this);
2020
2021 // Reserve the maximum.
2022
2023 // When compressed oops are enabled, the preferred heap base
2024 // is calculated by subtracting the requested size from the
2025 // 32Gb boundary and using the result as the base address for
2026 // heap reservation. If the requested size is not aligned to
2027 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2028 // into the ReservedHeapSpace constructor) then the actual
2029 // base of the reserved heap may end up differing from the
2030 // address that was requested (i.e. the preferred heap base).
2031 // If this happens then we could end up using a non-optimal
2032 // compressed oops mode.
2033
2034 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2035 heap_alignment);
2036
2037 // It is important to do this in a way such that concurrent readers can't
2038 // temporarily think something is in the heap. (I've actually seen this
2039 // happen in asserts: DLD.)
2040 _reserved.set_word_size(0);
2041 _reserved.set_start((HeapWord*)heap_rs.base());
2042 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2043
2044 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2045
2046 // Create the gen rem set (and barrier set) for the entire reserved region.
2047 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2048 set_barrier_set(rem_set()->bs());
2049 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2050 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2051 return JNI_ENOMEM;
2052 }
2053
2054 // Also create a G1 rem set.
2055 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2056
2057 // Carve out the G1 part of the heap.
2058
2059 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2060 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2061 g1_rs.size()/HeapWordSize);
2062
2063 _g1_storage.initialize(g1_rs, 0);
2064 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2065 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2066 (HeapWord*) _g1_reserved.end());
2067 assert(_hrs.max_length() == _expansion_regions,
2068 err_msg("max length: %u expansion regions: %u",
2069 _hrs.max_length(), _expansion_regions));
2070
2071 // Do later initialization work for concurrent refinement.
2072 _cg1r->init();
2073
2074 // 6843694 - ensure that the maximum region index can fit
2075 // in the remembered set structures.
2076 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2077 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2078
2079 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2080 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2081 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2082 "too many cards per region");
2083
2084 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2085
2086 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2087 heap_word_size(init_byte_size));
2088
2089 _g1h = this;
2090
2091 _in_cset_fast_test_length = max_regions();
2092 _in_cset_fast_test_base =
2093 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2094
2095 // We're biasing _in_cset_fast_test to avoid subtracting the
2096 // beginning of the heap every time we want to index; basically
2097 // it's the same with what we do with the card table.
2098 _in_cset_fast_test = _in_cset_fast_test_base -
2099 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2100
2101 // Clear the _cset_fast_test bitmap in anticipation of adding
2102 // regions to the incremental collection set for the first
2103 // evacuation pause.
2104 clear_cset_fast_test();
2105
2106 // Create the ConcurrentMark data structure and thread.
2107 // (Must do this late, so that "max_regions" is defined.)
2108 _cm = new ConcurrentMark(this, heap_rs);
2109 if (_cm == NULL || !_cm->completed_initialization()) {
2110 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2111 return JNI_ENOMEM;
2112 }
2113 _cmThread = _cm->cmThread();
2114
2115 // Initialize the from_card cache structure of HeapRegionRemSet.
2116 HeapRegionRemSet::init_heap(max_regions());
2117
2118 // Now expand into the initial heap size.
2119 if (!expand(init_byte_size)) {
2120 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2121 return JNI_ENOMEM;
2122 }
2123
2124 // Perform any initialization actions delegated to the policy.
2125 g1_policy()->init();
2126
2127 _refine_cte_cl =
2128 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2129 g1_rem_set(),
2130 concurrent_g1_refine());
2131 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2132
2133 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2134 SATB_Q_FL_lock,
2135 G1SATBProcessCompletedThreshold,
2136 Shared_SATB_Q_lock);
2137
2138 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2139 DirtyCardQ_FL_lock,
2140 concurrent_g1_refine()->yellow_zone(),
2141 concurrent_g1_refine()->red_zone(),
2142 Shared_DirtyCardQ_lock);
2143
2144 if (G1DeferredRSUpdate) {
2145 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2146 DirtyCardQ_FL_lock,
2147 -1, // never trigger processing
2148 -1, // no limit on length
2149 Shared_DirtyCardQ_lock,
2150 &JavaThread::dirty_card_queue_set());
2151 }
2152
2153 // Initialize the card queue set used to hold cards containing
2154 // references into the collection set.
2155 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2156 DirtyCardQ_FL_lock,
2157 -1, // never trigger processing
2158 -1, // no limit on length
2159 Shared_DirtyCardQ_lock,
2160 &JavaThread::dirty_card_queue_set());
2161
2162 // In case we're keeping closure specialization stats, initialize those
2163 // counts and that mechanism.
2164 SpecializationStats::clear();
2165
2166 // Here we allocate the dummy full region that is required by the
2167 // G1AllocRegion class. If we don't pass an address in the reserved
2168 // space here, lots of asserts fire.
2169
2170 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2171 _g1_reserved.start());
2172 // We'll re-use the same region whether the alloc region will
2173 // require BOT updates or not and, if it doesn't, then a non-young
2174 // region will complain that it cannot support allocations without
2175 // BOT updates. So we'll tag the dummy region as young to avoid that.
2176 dummy_region->set_young();
2177 // Make sure it's full.
2178 dummy_region->set_top(dummy_region->end());
2179 G1AllocRegion::setup(this, dummy_region);
2180
2181 init_mutator_alloc_region();
2182
2183 // Do create of the monitoring and management support so that
2184 // values in the heap have been properly initialized.
2185 _g1mm = new G1MonitoringSupport(this);
2186
2187 return JNI_OK;
2188 }
2189
2190 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2191 return HeapRegion::max_region_size();
2192 }
2193
2194 void G1CollectedHeap::ref_processing_init() {
2195 // Reference processing in G1 currently works as follows:
2196 //
2197 // * There are two reference processor instances. One is
2198 // used to record and process discovered references
2199 // during concurrent marking; the other is used to
2200 // record and process references during STW pauses
2201 // (both full and incremental).
2202 // * Both ref processors need to 'span' the entire heap as
2203 // the regions in the collection set may be dotted around.
2204 //
2205 // * For the concurrent marking ref processor:
2206 // * Reference discovery is enabled at initial marking.
2207 // * Reference discovery is disabled and the discovered
2208 // references processed etc during remarking.
2209 // * Reference discovery is MT (see below).
2210 // * Reference discovery requires a barrier (see below).
2211 // * Reference processing may or may not be MT
2212 // (depending on the value of ParallelRefProcEnabled
2213 // and ParallelGCThreads).
2214 // * A full GC disables reference discovery by the CM
2215 // ref processor and abandons any entries on it's
2216 // discovered lists.
2217 //
2218 // * For the STW processor:
2219 // * Non MT discovery is enabled at the start of a full GC.
2220 // * Processing and enqueueing during a full GC is non-MT.
2221 // * During a full GC, references are processed after marking.
2222 //
2223 // * Discovery (may or may not be MT) is enabled at the start
2224 // of an incremental evacuation pause.
2225 // * References are processed near the end of a STW evacuation pause.
2226 // * For both types of GC:
2227 // * Discovery is atomic - i.e. not concurrent.
2228 // * Reference discovery will not need a barrier.
2229
2230 SharedHeap::ref_processing_init();
2231 MemRegion mr = reserved_region();
2232
2233 // Concurrent Mark ref processor
2234 _ref_processor_cm =
2235 new ReferenceProcessor(mr, // span
2236 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2237 // mt processing
2238 (int) ParallelGCThreads,
2239 // degree of mt processing
2240 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2241 // mt discovery
2242 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2243 // degree of mt discovery
2244 false,
2245 // Reference discovery is not atomic
2246 &_is_alive_closure_cm,
2247 // is alive closure
2248 // (for efficiency/performance)
2249 true);
2250 // Setting next fields of discovered
2251 // lists requires a barrier.
2252
2253 // STW ref processor
2254 _ref_processor_stw =
2255 new ReferenceProcessor(mr, // span
2256 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2257 // mt processing
2258 MAX2((int)ParallelGCThreads, 1),
2259 // degree of mt processing
2260 (ParallelGCThreads > 1),
2261 // mt discovery
2262 MAX2((int)ParallelGCThreads, 1),
2263 // degree of mt discovery
2264 true,
2265 // Reference discovery is atomic
2266 &_is_alive_closure_stw,
2267 // is alive closure
2268 // (for efficiency/performance)
2269 false);
2270 // Setting next fields of discovered
2271 // lists requires a barrier.
2272 }
2273
2274 size_t G1CollectedHeap::capacity() const {
2275 return _g1_committed.byte_size();
2276 }
2277
2278 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2279 assert(!hr->continuesHumongous(), "pre-condition");
2280 hr->reset_gc_time_stamp();
2281 if (hr->startsHumongous()) {
2282 uint first_index = hr->hrs_index() + 1;
2283 uint last_index = hr->last_hc_index();
2284 for (uint i = first_index; i < last_index; i += 1) {
2285 HeapRegion* chr = region_at(i);
2286 assert(chr->continuesHumongous(), "sanity");
2287 chr->reset_gc_time_stamp();
2288 }
2289 }
2290 }
2291
2292 #ifndef PRODUCT
2293 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2294 private:
2295 unsigned _gc_time_stamp;
2296 bool _failures;
2297
2298 public:
2299 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2300 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2301
2302 virtual bool doHeapRegion(HeapRegion* hr) {
2303 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2304 if (_gc_time_stamp != region_gc_time_stamp) {
2305 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2306 "expected %d", HR_FORMAT_PARAMS(hr),
2307 region_gc_time_stamp, _gc_time_stamp);
2308 _failures = true;
2309 }
2310 return false;
2311 }
2312
2313 bool failures() { return _failures; }
2314 };
2315
2316 void G1CollectedHeap::check_gc_time_stamps() {
2317 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2318 heap_region_iterate(&cl);
2319 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2320 }
2321 #endif // PRODUCT
2322
2323 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2324 DirtyCardQueue* into_cset_dcq,
2325 bool concurrent,
2326 int worker_i) {
2327 // Clean cards in the hot card cache
2328 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2329 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2330
2331 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2332 int n_completed_buffers = 0;
2333 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2334 n_completed_buffers++;
2335 }
2336 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2337 dcqs.clear_n_completed_buffers();
2338 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2339 }
2340
2341
2342 // Computes the sum of the storage used by the various regions.
2343
2344 size_t G1CollectedHeap::used() const {
2345 assert(Heap_lock->owner() != NULL,
2346 "Should be owned on this thread's behalf.");
2347 size_t result = _summary_bytes_used;
2348 // Read only once in case it is set to NULL concurrently
2349 HeapRegion* hr = _mutator_alloc_region.get();
2350 if (hr != NULL)
2351 result += hr->used();
2352 return result;
2353 }
2354
2355 size_t G1CollectedHeap::used_unlocked() const {
2356 size_t result = _summary_bytes_used;
2357 return result;
2358 }
2359
2360 class SumUsedClosure: public HeapRegionClosure {
2361 size_t _used;
2362 public:
2363 SumUsedClosure() : _used(0) {}
2364 bool doHeapRegion(HeapRegion* r) {
2365 if (!r->continuesHumongous()) {
2366 _used += r->used();
2367 }
2368 return false;
2369 }
2370 size_t result() { return _used; }
2371 };
2372
2373 size_t G1CollectedHeap::recalculate_used() const {
2374 SumUsedClosure blk;
2375 heap_region_iterate(&blk);
2376 return blk.result();
2377 }
2378
2379 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2380 switch (cause) {
2381 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2382 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2383 case GCCause::_g1_humongous_allocation: return true;
2384 default: return false;
2385 }
2386 }
2387
2388 #ifndef PRODUCT
2389 void G1CollectedHeap::allocate_dummy_regions() {
2390 // Let's fill up most of the region
2391 size_t word_size = HeapRegion::GrainWords - 1024;
2392 // And as a result the region we'll allocate will be humongous.
2393 guarantee(isHumongous(word_size), "sanity");
2394
2395 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2396 // Let's use the existing mechanism for the allocation
2397 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2398 if (dummy_obj != NULL) {
2399 MemRegion mr(dummy_obj, word_size);
2400 CollectedHeap::fill_with_object(mr);
2401 } else {
2402 // If we can't allocate once, we probably cannot allocate
2403 // again. Let's get out of the loop.
2404 break;
2405 }
2406 }
2407 }
2408 #endif // !PRODUCT
2409
2410 void G1CollectedHeap::increment_old_marking_cycles_started() {
2411 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2412 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2413 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2414 _old_marking_cycles_started, _old_marking_cycles_completed));
2415
2416 _old_marking_cycles_started++;
2417 }
2418
2419 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2420 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2421
2422 // We assume that if concurrent == true, then the caller is a
2423 // concurrent thread that was joined the Suspendible Thread
2424 // Set. If there's ever a cheap way to check this, we should add an
2425 // assert here.
2426
2427 // Given that this method is called at the end of a Full GC or of a
2428 // concurrent cycle, and those can be nested (i.e., a Full GC can
2429 // interrupt a concurrent cycle), the number of full collections
2430 // completed should be either one (in the case where there was no
2431 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2432 // behind the number of full collections started.
2433
2434 // This is the case for the inner caller, i.e. a Full GC.
2435 assert(concurrent ||
2436 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2437 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2438 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2439 "is inconsistent with _old_marking_cycles_completed = %u",
2440 _old_marking_cycles_started, _old_marking_cycles_completed));
2441
2442 // This is the case for the outer caller, i.e. the concurrent cycle.
2443 assert(!concurrent ||
2444 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2445 err_msg("for outer caller (concurrent cycle): "
2446 "_old_marking_cycles_started = %u "
2447 "is inconsistent with _old_marking_cycles_completed = %u",
2448 _old_marking_cycles_started, _old_marking_cycles_completed));
2449
2450 _old_marking_cycles_completed += 1;
2451
2452 // We need to clear the "in_progress" flag in the CM thread before
2453 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2454 // is set) so that if a waiter requests another System.gc() it doesn't
2455 // incorrectly see that a marking cycle is still in progress.
2456 if (concurrent) {
2457 _cmThread->clear_in_progress();
2458 }
2459
2460 // This notify_all() will ensure that a thread that called
2461 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2462 // and it's waiting for a full GC to finish will be woken up. It is
2463 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2464 FullGCCount_lock->notify_all();
2465 }
2466
2467 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2468 _concurrent_cycle_started = true;
2469 _gc_timer_cm->register_gc_start(start_time);
2470
2471 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2472 trace_heap_before_gc(_gc_tracer_cm);
2473 }
2474
2475 void G1CollectedHeap::register_concurrent_cycle_end() {
2476 if (_concurrent_cycle_started) {
2477 if (_cm->has_aborted()) {
2478 _gc_tracer_cm->report_concurrent_mode_failure();
2479 }
2480
2481 _gc_timer_cm->register_gc_end();
2482 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2483
2484 _concurrent_cycle_started = false;
2485 }
2486 }
2487
2488 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2489 if (_concurrent_cycle_started) {
2490 trace_heap_after_gc(_gc_tracer_cm);
2491 }
2492 }
2493
2494 G1YCType G1CollectedHeap::yc_type() {
2495 bool is_young = g1_policy()->gcs_are_young();
2496 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2497 bool is_during_mark = mark_in_progress();
2498
2499 if (is_initial_mark) {
2500 return InitialMark;
2501 } else if (is_during_mark) {
2502 return DuringMark;
2503 } else if (is_young) {
2504 return Normal;
2505 } else {
2506 return Mixed;
2507 }
2508 }
2509
2510 void G1CollectedHeap::collect(GCCause::Cause cause) {
2511 assert_heap_not_locked();
2512
2513 unsigned int gc_count_before;
2514 unsigned int old_marking_count_before;
2515 bool retry_gc;
2516
2517 do {
2518 retry_gc = false;
2519
2520 {
2521 MutexLocker ml(Heap_lock);
2522
2523 // Read the GC count while holding the Heap_lock
2524 gc_count_before = total_collections();
2525 old_marking_count_before = _old_marking_cycles_started;
2526 }
2527
2528 if (should_do_concurrent_full_gc(cause)) {
2529 // Schedule an initial-mark evacuation pause that will start a
2530 // concurrent cycle. We're setting word_size to 0 which means that
2531 // we are not requesting a post-GC allocation.
2532 VM_G1IncCollectionPause op(gc_count_before,
2533 0, /* word_size */
2534 true, /* should_initiate_conc_mark */
2535 g1_policy()->max_pause_time_ms(),
2536 cause);
2537
2538 VMThread::execute(&op);
2539 if (!op.pause_succeeded()) {
2540 if (old_marking_count_before == _old_marking_cycles_started) {
2541 retry_gc = op.should_retry_gc();
2542 } else {
2543 // A Full GC happened while we were trying to schedule the
2544 // initial-mark GC. No point in starting a new cycle given
2545 // that the whole heap was collected anyway.
2546 }
2547
2548 if (retry_gc) {
2549 if (GC_locker::is_active_and_needs_gc()) {
2550 GC_locker::stall_until_clear();
2551 }
2552 }
2553 }
2554 } else {
2555 if (cause == GCCause::_gc_locker
2556 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2557
2558 // Schedule a standard evacuation pause. We're setting word_size
2559 // to 0 which means that we are not requesting a post-GC allocation.
2560 VM_G1IncCollectionPause op(gc_count_before,
2561 0, /* word_size */
2562 false, /* should_initiate_conc_mark */
2563 g1_policy()->max_pause_time_ms(),
2564 cause);
2565 VMThread::execute(&op);
2566 } else {
2567 // Schedule a Full GC.
2568 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2569 VMThread::execute(&op);
2570 }
2571 }
2572 } while (retry_gc);
2573 }
2574
2575 bool G1CollectedHeap::is_in(const void* p) const {
2576 if (_g1_committed.contains(p)) {
2577 // Given that we know that p is in the committed space,
2578 // heap_region_containing_raw() should successfully
2579 // return the containing region.
2580 HeapRegion* hr = heap_region_containing_raw(p);
2581 return hr->is_in(p);
2582 } else {
2583 return false;
2584 }
2585 }
2586
2587 // Iteration functions.
2588
2589 // Iterates an OopClosure over all ref-containing fields of objects
2590 // within a HeapRegion.
2591
2592 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2593 MemRegion _mr;
2594 ExtendedOopClosure* _cl;
2595 public:
2596 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2597 : _mr(mr), _cl(cl) {}
2598 bool doHeapRegion(HeapRegion* r) {
2599 if (!r->continuesHumongous()) {
2600 r->oop_iterate(_cl);
2601 }
2602 return false;
2603 }
2604 };
2605
2606 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2607 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2608 heap_region_iterate(&blk);
2609 }
2610
2611 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2612 IterateOopClosureRegionClosure blk(mr, cl);
2613 heap_region_iterate(&blk);
2614 }
2615
2616 // Iterates an ObjectClosure over all objects within a HeapRegion.
2617
2618 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2619 ObjectClosure* _cl;
2620 public:
2621 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2622 bool doHeapRegion(HeapRegion* r) {
2623 if (! r->continuesHumongous()) {
2624 r->object_iterate(_cl);
2625 }
2626 return false;
2627 }
2628 };
2629
2630 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2631 IterateObjectClosureRegionClosure blk(cl);
2632 heap_region_iterate(&blk);
2633 }
2634
2635 // Calls a SpaceClosure on a HeapRegion.
2636
2637 class SpaceClosureRegionClosure: public HeapRegionClosure {
2638 SpaceClosure* _cl;
2639 public:
2640 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2641 bool doHeapRegion(HeapRegion* r) {
2642 _cl->do_space(r);
2643 return false;
2644 }
2645 };
2646
2647 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2648 SpaceClosureRegionClosure blk(cl);
2649 heap_region_iterate(&blk);
2650 }
2651
2652 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2653 _hrs.iterate(cl);
2654 }
2655
2656 void
2657 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2658 uint worker_id,
2659 uint no_of_par_workers,
2660 jint claim_value) {
2661 const uint regions = n_regions();
2662 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2663 no_of_par_workers :
2664 1);
2665 assert(UseDynamicNumberOfGCThreads ||
2666 no_of_par_workers == workers()->total_workers(),
2667 "Non dynamic should use fixed number of workers");
2668 // try to spread out the starting points of the workers
2669 const HeapRegion* start_hr =
2670 start_region_for_worker(worker_id, no_of_par_workers);
2671 const uint start_index = start_hr->hrs_index();
2672
2673 // each worker will actually look at all regions
2674 for (uint count = 0; count < regions; ++count) {
2675 const uint index = (start_index + count) % regions;
2676 assert(0 <= index && index < regions, "sanity");
2677 HeapRegion* r = region_at(index);
2678 // we'll ignore "continues humongous" regions (we'll process them
2679 // when we come across their corresponding "start humongous"
2680 // region) and regions already claimed
2681 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2682 continue;
2683 }
2684 // OK, try to claim it
2685 if (r->claimHeapRegion(claim_value)) {
2686 // success!
2687 assert(!r->continuesHumongous(), "sanity");
2688 if (r->startsHumongous()) {
2689 // If the region is "starts humongous" we'll iterate over its
2690 // "continues humongous" first; in fact we'll do them
2691 // first. The order is important. In on case, calling the
2692 // closure on the "starts humongous" region might de-allocate
2693 // and clear all its "continues humongous" regions and, as a
2694 // result, we might end up processing them twice. So, we'll do
2695 // them first (notice: most closures will ignore them anyway) and
2696 // then we'll do the "starts humongous" region.
2697 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2698 HeapRegion* chr = region_at(ch_index);
2699
2700 // if the region has already been claimed or it's not
2701 // "continues humongous" we're done
2702 if (chr->claim_value() == claim_value ||
2703 !chr->continuesHumongous()) {
2704 break;
2705 }
2706
2707 // No one should have claimed it directly. We can given
2708 // that we claimed its "starts humongous" region.
2709 assert(chr->claim_value() != claim_value, "sanity");
2710 assert(chr->humongous_start_region() == r, "sanity");
2711
2712 if (chr->claimHeapRegion(claim_value)) {
2713 // we should always be able to claim it; no one else should
2714 // be trying to claim this region
2715
2716 bool res2 = cl->doHeapRegion(chr);
2717 assert(!res2, "Should not abort");
2718
2719 // Right now, this holds (i.e., no closure that actually
2720 // does something with "continues humongous" regions
2721 // clears them). We might have to weaken it in the future,
2722 // but let's leave these two asserts here for extra safety.
2723 assert(chr->continuesHumongous(), "should still be the case");
2724 assert(chr->humongous_start_region() == r, "sanity");
2725 } else {
2726 guarantee(false, "we should not reach here");
2727 }
2728 }
2729 }
2730
2731 assert(!r->continuesHumongous(), "sanity");
2732 bool res = cl->doHeapRegion(r);
2733 assert(!res, "Should not abort");
2734 }
2735 }
2736 }
2737
2738 class ResetClaimValuesClosure: public HeapRegionClosure {
2739 public:
2740 bool doHeapRegion(HeapRegion* r) {
2741 r->set_claim_value(HeapRegion::InitialClaimValue);
2742 return false;
2743 }
2744 };
2745
2746 void G1CollectedHeap::reset_heap_region_claim_values() {
2747 ResetClaimValuesClosure blk;
2748 heap_region_iterate(&blk);
2749 }
2750
2751 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2752 ResetClaimValuesClosure blk;
2753 collection_set_iterate(&blk);
2754 }
2755
2756 #ifdef ASSERT
2757 // This checks whether all regions in the heap have the correct claim
2758 // value. I also piggy-backed on this a check to ensure that the
2759 // humongous_start_region() information on "continues humongous"
2760 // regions is correct.
2761
2762 class CheckClaimValuesClosure : public HeapRegionClosure {
2763 private:
2764 jint _claim_value;
2765 uint _failures;
2766 HeapRegion* _sh_region;
2767
2768 public:
2769 CheckClaimValuesClosure(jint claim_value) :
2770 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2771 bool doHeapRegion(HeapRegion* r) {
2772 if (r->claim_value() != _claim_value) {
2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2774 "claim value = %d, should be %d",
2775 HR_FORMAT_PARAMS(r),
2776 r->claim_value(), _claim_value);
2777 ++_failures;
2778 }
2779 if (!r->isHumongous()) {
2780 _sh_region = NULL;
2781 } else if (r->startsHumongous()) {
2782 _sh_region = r;
2783 } else if (r->continuesHumongous()) {
2784 if (r->humongous_start_region() != _sh_region) {
2785 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2786 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2787 HR_FORMAT_PARAMS(r),
2788 r->humongous_start_region(),
2789 _sh_region);
2790 ++_failures;
2791 }
2792 }
2793 return false;
2794 }
2795 uint failures() { return _failures; }
2796 };
2797
2798 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2799 CheckClaimValuesClosure cl(claim_value);
2800 heap_region_iterate(&cl);
2801 return cl.failures() == 0;
2802 }
2803
2804 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2805 private:
2806 jint _claim_value;
2807 uint _failures;
2808
2809 public:
2810 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2811 _claim_value(claim_value), _failures(0) { }
2812
2813 uint failures() { return _failures; }
2814
2815 bool doHeapRegion(HeapRegion* hr) {
2816 assert(hr->in_collection_set(), "how?");
2817 assert(!hr->isHumongous(), "H-region in CSet");
2818 if (hr->claim_value() != _claim_value) {
2819 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2820 "claim value = %d, should be %d",
2821 HR_FORMAT_PARAMS(hr),
2822 hr->claim_value(), _claim_value);
2823 _failures += 1;
2824 }
2825 return false;
2826 }
2827 };
2828
2829 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2830 CheckClaimValuesInCSetHRClosure cl(claim_value);
2831 collection_set_iterate(&cl);
2832 return cl.failures() == 0;
2833 }
2834 #endif // ASSERT
2835
2836 // Clear the cached CSet starting regions and (more importantly)
2837 // the time stamps. Called when we reset the GC time stamp.
2838 void G1CollectedHeap::clear_cset_start_regions() {
2839 assert(_worker_cset_start_region != NULL, "sanity");
2840 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2841
2842 int n_queues = MAX2((int)ParallelGCThreads, 1);
2843 for (int i = 0; i < n_queues; i++) {
2844 _worker_cset_start_region[i] = NULL;
2845 _worker_cset_start_region_time_stamp[i] = 0;
2846 }
2847 }
2848
2849 // Given the id of a worker, obtain or calculate a suitable
2850 // starting region for iterating over the current collection set.
2851 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2852 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2853
2854 HeapRegion* result = NULL;
2855 unsigned gc_time_stamp = get_gc_time_stamp();
2856
2857 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2858 // Cached starting region for current worker was set
2859 // during the current pause - so it's valid.
2860 // Note: the cached starting heap region may be NULL
2861 // (when the collection set is empty).
2862 result = _worker_cset_start_region[worker_i];
2863 assert(result == NULL || result->in_collection_set(), "sanity");
2864 return result;
2865 }
2866
2867 // The cached entry was not valid so let's calculate
2868 // a suitable starting heap region for this worker.
2869
2870 // We want the parallel threads to start their collection
2871 // set iteration at different collection set regions to
2872 // avoid contention.
2873 // If we have:
2874 // n collection set regions
2875 // p threads
2876 // Then thread t will start at region floor ((t * n) / p)
2877
2878 result = g1_policy()->collection_set();
2879 if (G1CollectedHeap::use_parallel_gc_threads()) {
2880 uint cs_size = g1_policy()->cset_region_length();
2881 uint active_workers = workers()->active_workers();
2882 assert(UseDynamicNumberOfGCThreads ||
2883 active_workers == workers()->total_workers(),
2884 "Unless dynamic should use total workers");
2885
2886 uint end_ind = (cs_size * worker_i) / active_workers;
2887 uint start_ind = 0;
2888
2889 if (worker_i > 0 &&
2890 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2891 // Previous workers starting region is valid
2892 // so let's iterate from there
2893 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2894 result = _worker_cset_start_region[worker_i - 1];
2895 }
2896
2897 for (uint i = start_ind; i < end_ind; i++) {
2898 result = result->next_in_collection_set();
2899 }
2900 }
2901
2902 // Note: the calculated starting heap region may be NULL
2903 // (when the collection set is empty).
2904 assert(result == NULL || result->in_collection_set(), "sanity");
2905 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2906 "should be updated only once per pause");
2907 _worker_cset_start_region[worker_i] = result;
2908 OrderAccess::storestore();
2909 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2910 return result;
2911 }
2912
2913 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2914 uint no_of_par_workers) {
2915 uint worker_num =
2916 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2917 assert(UseDynamicNumberOfGCThreads ||
2918 no_of_par_workers == workers()->total_workers(),
2919 "Non dynamic should use fixed number of workers");
2920 const uint start_index = n_regions() * worker_i / worker_num;
2921 return region_at(start_index);
2922 }
2923
2924 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2925 HeapRegion* r = g1_policy()->collection_set();
2926 while (r != NULL) {
2927 HeapRegion* next = r->next_in_collection_set();
2928 if (cl->doHeapRegion(r)) {
2929 cl->incomplete();
2930 return;
2931 }
2932 r = next;
2933 }
2934 }
2935
2936 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2937 HeapRegionClosure *cl) {
2938 if (r == NULL) {
2939 // The CSet is empty so there's nothing to do.
2940 return;
2941 }
2942
2943 assert(r->in_collection_set(),
2944 "Start region must be a member of the collection set.");
2945 HeapRegion* cur = r;
2946 while (cur != NULL) {
2947 HeapRegion* next = cur->next_in_collection_set();
2948 if (cl->doHeapRegion(cur) && false) {
2949 cl->incomplete();
2950 return;
2951 }
2952 cur = next;
2953 }
2954 cur = g1_policy()->collection_set();
2955 while (cur != r) {
2956 HeapRegion* next = cur->next_in_collection_set();
2957 if (cl->doHeapRegion(cur) && false) {
2958 cl->incomplete();
2959 return;
2960 }
2961 cur = next;
2962 }
2963 }
2964
2965 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2966 return n_regions() > 0 ? region_at(0) : NULL;
2967 }
2968
2969
2970 Space* G1CollectedHeap::space_containing(const void* addr) const {
2971 Space* res = heap_region_containing(addr);
2972 return res;
2973 }
2974
2975 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2976 Space* sp = space_containing(addr);
2977 if (sp != NULL) {
2978 return sp->block_start(addr);
2979 }
2980 return NULL;
2981 }
2982
2983 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2984 Space* sp = space_containing(addr);
2985 assert(sp != NULL, "block_size of address outside of heap");
2986 return sp->block_size(addr);
2987 }
2988
2989 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2990 Space* sp = space_containing(addr);
2991 return sp->block_is_obj(addr);
2992 }
2993
2994 bool G1CollectedHeap::supports_tlab_allocation() const {
2995 return true;
2996 }
2997
2998 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2999 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
3000 }
3001
3002 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3003 return young_list()->eden_used_bytes();
3004 }
3005
3006 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3007 // must be smaller than the humongous object limit.
3008 size_t G1CollectedHeap::max_tlab_size() const {
3009 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3010 }
3011
3012 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3013 // Return the remaining space in the cur alloc region, but not less than
3014 // the min TLAB size.
3015
3016 // Also, this value can be at most the humongous object threshold,
3017 // since we can't allow tlabs to grow big enough to accommodate
3018 // humongous objects.
3019
3020 HeapRegion* hr = _mutator_alloc_region.get();
3021 size_t max_tlab = max_tlab_size() * wordSize;
3022 if (hr == NULL) {
3023 return max_tlab;
3024 } else {
3025 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3026 }
3027 }
3028
3029 size_t G1CollectedHeap::max_capacity() const {
3030 return _g1_reserved.byte_size();
3031 }
3032
3033 jlong G1CollectedHeap::millis_since_last_gc() {
3034 // assert(false, "NYI");
3035 return 0;
3036 }
3037
3038 void G1CollectedHeap::prepare_for_verify() {
3039 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3040 ensure_parsability(false);
3041 }
3042 g1_rem_set()->prepare_for_verify();
3043 }
3044
3045 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3046 VerifyOption vo) {
3047 switch (vo) {
3048 case VerifyOption_G1UsePrevMarking:
3049 return hr->obj_allocated_since_prev_marking(obj);
3050 case VerifyOption_G1UseNextMarking:
3051 return hr->obj_allocated_since_next_marking(obj);
3052 case VerifyOption_G1UseMarkWord:
3053 return false;
3054 default:
3055 ShouldNotReachHere();
3056 }
3057 return false; // keep some compilers happy
3058 }
3059
3060 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3061 switch (vo) {
3062 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3063 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3064 case VerifyOption_G1UseMarkWord: return NULL;
3065 default: ShouldNotReachHere();
3066 }
3067 return NULL; // keep some compilers happy
3068 }
3069
3070 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3071 switch (vo) {
3072 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3073 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3074 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3075 default: ShouldNotReachHere();
3076 }
3077 return false; // keep some compilers happy
3078 }
3079
3080 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3081 switch (vo) {
3082 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3083 case VerifyOption_G1UseNextMarking: return "NTAMS";
3084 case VerifyOption_G1UseMarkWord: return "NONE";
3085 default: ShouldNotReachHere();
3086 }
3087 return NULL; // keep some compilers happy
3088 }
3089
3090 class VerifyRootsClosure: public OopClosure {
3091 private:
3092 G1CollectedHeap* _g1h;
3093 VerifyOption _vo;
3094 bool _failures;
3095 public:
3096 // _vo == UsePrevMarking -> use "prev" marking information,
3097 // _vo == UseNextMarking -> use "next" marking information,
3098 // _vo == UseMarkWord -> use mark word from object header.
3099 VerifyRootsClosure(VerifyOption vo) :
3100 _g1h(G1CollectedHeap::heap()),
3101 _vo(vo),
3102 _failures(false) { }
3103
3104 bool failures() { return _failures; }
3105
3106 template <class T> void do_oop_nv(T* p) {
3107 T heap_oop = oopDesc::load_heap_oop(p);
3108 if (!oopDesc::is_null(heap_oop)) {
3109 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3110 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3111 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3112 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3113 if (_vo == VerifyOption_G1UseMarkWord) {
3114 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3115 }
3116 obj->print_on(gclog_or_tty);
3117 _failures = true;
3118 }
3119 }
3120 }
3121
3122 void do_oop(oop* p) { do_oop_nv(p); }
3123 void do_oop(narrowOop* p) { do_oop_nv(p); }
3124 };
3125
3126 class G1VerifyCodeRootOopClosure: public OopClosure {
3127 G1CollectedHeap* _g1h;
3128 OopClosure* _root_cl;
3129 nmethod* _nm;
3130 VerifyOption _vo;
3131 bool _failures;
3132
3133 template <class T> void do_oop_work(T* p) {
3134 // First verify that this root is live
3135 _root_cl->do_oop(p);
3136
3137 if (!G1VerifyHeapRegionCodeRoots) {
3138 // We're not verifying the code roots attached to heap region.
3139 return;
3140 }
3141
3142 // Don't check the code roots during marking verification in a full GC
3143 if (_vo == VerifyOption_G1UseMarkWord) {
3144 return;
3145 }
3146
3147 // Now verify that the current nmethod (which contains p) is
3148 // in the code root list of the heap region containing the
3149 // object referenced by p.
3150
3151 T heap_oop = oopDesc::load_heap_oop(p);
3152 if (!oopDesc::is_null(heap_oop)) {
3153 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3154
3155 // Now fetch the region containing the object
3156 HeapRegion* hr = _g1h->heap_region_containing(obj);
3157 HeapRegionRemSet* hrrs = hr->rem_set();
3158 // Verify that the strong code root list for this region
3159 // contains the nmethod
3160 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3161 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3162 "from nmethod "PTR_FORMAT" not in strong "
3163 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3164 p, _nm, hr->bottom(), hr->end());
3165 _failures = true;
3166 }
3167 }
3168 }
3169
3170 public:
3171 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3172 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3173
3174 void do_oop(oop* p) { do_oop_work(p); }
3175 void do_oop(narrowOop* p) { do_oop_work(p); }
3176
3177 void set_nmethod(nmethod* nm) { _nm = nm; }
3178 bool failures() { return _failures; }
3179 };
3180
3181 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3182 G1VerifyCodeRootOopClosure* _oop_cl;
3183
3184 public:
3185 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3186 _oop_cl(oop_cl) {}
3187
3188 void do_code_blob(CodeBlob* cb) {
3189 nmethod* nm = cb->as_nmethod_or_null();
3190 if (nm != NULL) {
3191 _oop_cl->set_nmethod(nm);
3192 nm->oops_do(_oop_cl);
3193 }
3194 }
3195 };
3196
3197 class YoungRefCounterClosure : public OopClosure {
3198 G1CollectedHeap* _g1h;
3199 int _count;
3200 public:
3201 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3202 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3203 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3204
3205 int count() { return _count; }
3206 void reset_count() { _count = 0; };
3207 };
3208
3209 class VerifyKlassClosure: public KlassClosure {
3210 YoungRefCounterClosure _young_ref_counter_closure;
3211 OopClosure *_oop_closure;
3212 public:
3213 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3214 void do_klass(Klass* k) {
3215 k->oops_do(_oop_closure);
3216
3217 _young_ref_counter_closure.reset_count();
3218 k->oops_do(&_young_ref_counter_closure);
3219 if (_young_ref_counter_closure.count() > 0) {
3220 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3221 }
3222 }
3223 };
3224
3225 class VerifyLivenessOopClosure: public OopClosure {
3226 G1CollectedHeap* _g1h;
3227 VerifyOption _vo;
3228 public:
3229 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3230 _g1h(g1h), _vo(vo)
3231 { }
3232 void do_oop(narrowOop *p) { do_oop_work(p); }
3233 void do_oop( oop *p) { do_oop_work(p); }
3234
3235 template <class T> void do_oop_work(T *p) {
3236 oop obj = oopDesc::load_decode_heap_oop(p);
3237 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3238 "Dead object referenced by a not dead object");
3239 }
3240 };
3241
3242 class VerifyObjsInRegionClosure: public ObjectClosure {
3243 private:
3244 G1CollectedHeap* _g1h;
3245 size_t _live_bytes;
3246 HeapRegion *_hr;
3247 VerifyOption _vo;
3248 public:
3249 // _vo == UsePrevMarking -> use "prev" marking information,
3250 // _vo == UseNextMarking -> use "next" marking information,
3251 // _vo == UseMarkWord -> use mark word from object header.
3252 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3253 : _live_bytes(0), _hr(hr), _vo(vo) {
3254 _g1h = G1CollectedHeap::heap();
3255 }
3256 void do_object(oop o) {
3257 VerifyLivenessOopClosure isLive(_g1h, _vo);
3258 assert(o != NULL, "Huh?");
3259 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3260 // If the object is alive according to the mark word,
3261 // then verify that the marking information agrees.
3262 // Note we can't verify the contra-positive of the
3263 // above: if the object is dead (according to the mark
3264 // word), it may not be marked, or may have been marked
3265 // but has since became dead, or may have been allocated
3266 // since the last marking.
3267 if (_vo == VerifyOption_G1UseMarkWord) {
3268 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3269 }
3270
3271 o->oop_iterate_no_header(&isLive);
3272 if (!_hr->obj_allocated_since_prev_marking(o)) {
3273 size_t obj_size = o->size(); // Make sure we don't overflow
3274 _live_bytes += (obj_size * HeapWordSize);
3275 }
3276 }
3277 }
3278 size_t live_bytes() { return _live_bytes; }
3279 };
3280
3281 class PrintObjsInRegionClosure : public ObjectClosure {
3282 HeapRegion *_hr;
3283 G1CollectedHeap *_g1;
3284 public:
3285 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3286 _g1 = G1CollectedHeap::heap();
3287 };
3288
3289 void do_object(oop o) {
3290 if (o != NULL) {
3291 HeapWord *start = (HeapWord *) o;
3292 size_t word_sz = o->size();
3293 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3294 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3295 (void*) o, word_sz,
3296 _g1->isMarkedPrev(o),
3297 _g1->isMarkedNext(o),
3298 _hr->obj_allocated_since_prev_marking(o));
3299 HeapWord *end = start + word_sz;
3300 HeapWord *cur;
3301 int *val;
3302 for (cur = start; cur < end; cur++) {
3303 val = (int *) cur;
3304 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3305 }
3306 }
3307 }
3308 };
3309
3310 class VerifyRegionClosure: public HeapRegionClosure {
3311 private:
3312 bool _par;
3313 VerifyOption _vo;
3314 bool _failures;
3315 public:
3316 // _vo == UsePrevMarking -> use "prev" marking information,
3317 // _vo == UseNextMarking -> use "next" marking information,
3318 // _vo == UseMarkWord -> use mark word from object header.
3319 VerifyRegionClosure(bool par, VerifyOption vo)
3320 : _par(par),
3321 _vo(vo),
3322 _failures(false) {}
3323
3324 bool failures() {
3325 return _failures;
3326 }
3327
3328 bool doHeapRegion(HeapRegion* r) {
3329 if (!r->continuesHumongous()) {
3330 bool failures = false;
3331 r->verify(_vo, &failures);
3332 if (failures) {
3333 _failures = true;
3334 } else {
3335 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3336 r->object_iterate(¬_dead_yet_cl);
3337 if (_vo != VerifyOption_G1UseNextMarking) {
3338 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3339 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3340 "max_live_bytes "SIZE_FORMAT" "
3341 "< calculated "SIZE_FORMAT,
3342 r->bottom(), r->end(),
3343 r->max_live_bytes(),
3344 not_dead_yet_cl.live_bytes());
3345 _failures = true;
3346 }
3347 } else {
3348 // When vo == UseNextMarking we cannot currently do a sanity
3349 // check on the live bytes as the calculation has not been
3350 // finalized yet.
3351 }
3352 }
3353 }
3354 return false; // stop the region iteration if we hit a failure
3355 }
3356 };
3357
3358 // This is the task used for parallel verification of the heap regions
3359
3360 class G1ParVerifyTask: public AbstractGangTask {
3361 private:
3362 G1CollectedHeap* _g1h;
3363 VerifyOption _vo;
3364 bool _failures;
3365
3366 public:
3367 // _vo == UsePrevMarking -> use "prev" marking information,
3368 // _vo == UseNextMarking -> use "next" marking information,
3369 // _vo == UseMarkWord -> use mark word from object header.
3370 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3371 AbstractGangTask("Parallel verify task"),
3372 _g1h(g1h),
3373 _vo(vo),
3374 _failures(false) { }
3375
3376 bool failures() {
3377 return _failures;
3378 }
3379
3380 void work(uint worker_id) {
3381 HandleMark hm;
3382 VerifyRegionClosure blk(true, _vo);
3383 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3384 _g1h->workers()->active_workers(),
3385 HeapRegion::ParVerifyClaimValue);
3386 if (blk.failures()) {
3387 _failures = true;
3388 }
3389 }
3390 };
3391
3392 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3393 if (SafepointSynchronize::is_at_safepoint()) {
3394 assert(Thread::current()->is_VM_thread(),
3395 "Expected to be executed serially by the VM thread at this point");
3396
3397 if (!silent) { gclog_or_tty->print("Roots "); }
3398 VerifyRootsClosure rootsCl(vo);
3399 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3400 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3401 VerifyKlassClosure klassCl(this, &rootsCl);
3402
3403 // We apply the relevant closures to all the oops in the
3404 // system dictionary, the string table and the code cache.
3405 const int so = SO_AllClasses | SO_Strings | SO_AllCodeCache;
3406
3407 // Need cleared claim bits for the strong roots processing
3408 ClassLoaderDataGraph::clear_claimed_marks();
3409
3410 process_strong_roots(true, // activate StrongRootsScope
3411 ScanningOption(so), // roots scanning options
3412 &rootsCl,
3413 &blobsCl,
3414 &klassCl
3415 );
3416
3417 bool failures = rootsCl.failures() || codeRootsCl.failures();
3418
3419 if (vo != VerifyOption_G1UseMarkWord) {
3420 // If we're verifying during a full GC then the region sets
3421 // will have been torn down at the start of the GC. Therefore
3422 // verifying the region sets will fail. So we only verify
3423 // the region sets when not in a full GC.
3424 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3425 verify_region_sets();
3426 }
3427
3428 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3429 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3430 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3431 "sanity check");
3432
3433 G1ParVerifyTask task(this, vo);
3434 assert(UseDynamicNumberOfGCThreads ||
3435 workers()->active_workers() == workers()->total_workers(),
3436 "If not dynamic should be using all the workers");
3437 int n_workers = workers()->active_workers();
3438 set_par_threads(n_workers);
3439 workers()->run_task(&task);
3440 set_par_threads(0);
3441 if (task.failures()) {
3442 failures = true;
3443 }
3444
3445 // Checks that the expected amount of parallel work was done.
3446 // The implication is that n_workers is > 0.
3447 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3448 "sanity check");
3449
3450 reset_heap_region_claim_values();
3451
3452 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3453 "sanity check");
3454 } else {
3455 VerifyRegionClosure blk(false, vo);
3456 heap_region_iterate(&blk);
3457 if (blk.failures()) {
3458 failures = true;
3459 }
3460 }
3461 if (!silent) gclog_or_tty->print("RemSet ");
3462 rem_set()->verify();
3463
3464 if (failures) {
3465 gclog_or_tty->print_cr("Heap:");
3466 // It helps to have the per-region information in the output to
3467 // help us track down what went wrong. This is why we call
3468 // print_extended_on() instead of print_on().
3469 print_extended_on(gclog_or_tty);
3470 gclog_or_tty->print_cr("");
3471 #ifndef PRODUCT
3472 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3473 concurrent_mark()->print_reachable("at-verification-failure",
3474 vo, false /* all */);
3475 }
3476 #endif
3477 gclog_or_tty->flush();
3478 }
3479 guarantee(!failures, "there should not have been any failures");
3480 } else {
3481 if (!silent)
3482 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3483 }
3484 }
3485
3486 void G1CollectedHeap::verify(bool silent) {
3487 verify(silent, VerifyOption_G1UsePrevMarking);
3488 }
3489
3490 double G1CollectedHeap::verify(bool guard, const char* msg) {
3491 double verify_time_ms = 0.0;
3492
3493 if (guard && total_collections() >= VerifyGCStartAt) {
3494 double verify_start = os::elapsedTime();
3495 HandleMark hm; // Discard invalid handles created during verification
3496 prepare_for_verify();
3497 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3498 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3499 }
3500
3501 return verify_time_ms;
3502 }
3503
3504 void G1CollectedHeap::verify_before_gc() {
3505 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3506 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3507 }
3508
3509 void G1CollectedHeap::verify_after_gc() {
3510 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3511 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3512 }
3513
3514 class PrintRegionClosure: public HeapRegionClosure {
3515 outputStream* _st;
3516 public:
3517 PrintRegionClosure(outputStream* st) : _st(st) {}
3518 bool doHeapRegion(HeapRegion* r) {
3519 r->print_on(_st);
3520 return false;
3521 }
3522 };
3523
3524 void G1CollectedHeap::print_on(outputStream* st) const {
3525 st->print(" %-20s", "garbage-first heap");
3526 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3527 capacity()/K, used_unlocked()/K);
3528 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3529 _g1_storage.low_boundary(),
3530 _g1_storage.high(),
3531 _g1_storage.high_boundary());
3532 st->cr();
3533 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3534 uint young_regions = _young_list->length();
3535 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3536 (size_t) young_regions * HeapRegion::GrainBytes / K);
3537 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3538 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3539 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3540 st->cr();
3541 MetaspaceAux::print_on(st);
3542 }
3543
3544 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3545 print_on(st);
3546
3547 // Print the per-region information.
3548 st->cr();
3549 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3550 "HS=humongous(starts), HC=humongous(continues), "
3551 "CS=collection set, F=free, TS=gc time stamp, "
3552 "PTAMS=previous top-at-mark-start, "
3553 "NTAMS=next top-at-mark-start)");
3554 PrintRegionClosure blk(st);
3555 heap_region_iterate(&blk);
3556 }
3557
3558 void G1CollectedHeap::print_on_error(outputStream* st) const {
3559 this->CollectedHeap::print_on_error(st);
3560
3561 if (_cm != NULL) {
3562 st->cr();
3563 _cm->print_on_error(st);
3564 }
3565 }
3566
3567 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3568 if (G1CollectedHeap::use_parallel_gc_threads()) {
3569 workers()->print_worker_threads_on(st);
3570 }
3571 _cmThread->print_on(st);
3572 st->cr();
3573 _cm->print_worker_threads_on(st);
3574 _cg1r->print_worker_threads_on(st);
3575 }
3576
3577 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3578 if (G1CollectedHeap::use_parallel_gc_threads()) {
3579 workers()->threads_do(tc);
3580 }
3581 tc->do_thread(_cmThread);
3582 _cg1r->threads_do(tc);
3583 }
3584
3585 void G1CollectedHeap::print_tracing_info() const {
3586 // We'll overload this to mean "trace GC pause statistics."
3587 if (TraceGen0Time || TraceGen1Time) {
3588 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3589 // to that.
3590 g1_policy()->print_tracing_info();
3591 }
3592 if (G1SummarizeRSetStats) {
3593 g1_rem_set()->print_summary_info();
3594 }
3595 if (G1SummarizeConcMark) {
3596 concurrent_mark()->print_summary_info();
3597 }
3598 g1_policy()->print_yg_surv_rate_info();
3599 SpecializationStats::print();
3600 }
3601
3602 #ifndef PRODUCT
3603 // Helpful for debugging RSet issues.
3604
3605 class PrintRSetsClosure : public HeapRegionClosure {
3606 private:
3607 const char* _msg;
3608 size_t _occupied_sum;
3609
3610 public:
3611 bool doHeapRegion(HeapRegion* r) {
3612 HeapRegionRemSet* hrrs = r->rem_set();
3613 size_t occupied = hrrs->occupied();
3614 _occupied_sum += occupied;
3615
3616 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3617 HR_FORMAT_PARAMS(r));
3618 if (occupied == 0) {
3619 gclog_or_tty->print_cr(" RSet is empty");
3620 } else {
3621 hrrs->print();
3622 }
3623 gclog_or_tty->print_cr("----------");
3624 return false;
3625 }
3626
3627 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3628 gclog_or_tty->cr();
3629 gclog_or_tty->print_cr("========================================");
3630 gclog_or_tty->print_cr(msg);
3631 gclog_or_tty->cr();
3632 }
3633
3634 ~PrintRSetsClosure() {
3635 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3636 gclog_or_tty->print_cr("========================================");
3637 gclog_or_tty->cr();
3638 }
3639 };
3640
3641 void G1CollectedHeap::print_cset_rsets() {
3642 PrintRSetsClosure cl("Printing CSet RSets");
3643 collection_set_iterate(&cl);
3644 }
3645
3646 void G1CollectedHeap::print_all_rsets() {
3647 PrintRSetsClosure cl("Printing All RSets");;
3648 heap_region_iterate(&cl);
3649 }
3650 #endif // PRODUCT
3651
3652 G1CollectedHeap* G1CollectedHeap::heap() {
3653 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3654 "not a garbage-first heap");
3655 return _g1h;
3656 }
3657
3658 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3659 // always_do_update_barrier = false;
3660 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3661 // Fill TLAB's and such
3662 accumulate_statistics_all_tlabs();
3663 ensure_parsability(true);
3664
3665 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3666 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3667 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3668 }
3669 }
3670
3671 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3672
3673 if (G1SummarizeRSetStats &&
3674 (G1SummarizeRSetStatsPeriod > 0) &&
3675 // we are at the end of the GC. Total collections has already been increased.
3676 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3677 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3678 }
3679
3680 // FIXME: what is this about?
3681 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3682 // is set.
3683 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3684 "derived pointer present"));
3685 // always_do_update_barrier = true;
3686
3687 resize_all_tlabs();
3688
3689 // We have just completed a GC. Update the soft reference
3690 // policy with the new heap occupancy
3691 Universe::update_heap_info_at_gc();
3692 }
3693
3694 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3695 unsigned int gc_count_before,
3696 bool* succeeded,
3697 GCCause::Cause gc_cause) {
3698 assert_heap_not_locked_and_not_at_safepoint();
3699 g1_policy()->record_stop_world_start();
3700 VM_G1IncCollectionPause op(gc_count_before,
3701 word_size,
3702 false, /* should_initiate_conc_mark */
3703 g1_policy()->max_pause_time_ms(),
3704 gc_cause);
3705 VMThread::execute(&op);
3706
3707 HeapWord* result = op.result();
3708 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3709 assert(result == NULL || ret_succeeded,
3710 "the result should be NULL if the VM did not succeed");
3711 *succeeded = ret_succeeded;
3712
3713 assert_heap_not_locked();
3714 return result;
3715 }
3716
3717 void
3718 G1CollectedHeap::doConcurrentMark() {
3719 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3720 if (!_cmThread->in_progress()) {
3721 _cmThread->set_started();
3722 CGC_lock->notify();
3723 }
3724 }
3725
3726 size_t G1CollectedHeap::pending_card_num() {
3727 size_t extra_cards = 0;
3728 JavaThread *curr = Threads::first();
3729 while (curr != NULL) {
3730 DirtyCardQueue& dcq = curr->dirty_card_queue();
3731 extra_cards += dcq.size();
3732 curr = curr->next();
3733 }
3734 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3735 size_t buffer_size = dcqs.buffer_size();
3736 size_t buffer_num = dcqs.completed_buffers_num();
3737
3738 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3739 // in bytes - not the number of 'entries'. We need to convert
3740 // into a number of cards.
3741 return (buffer_size * buffer_num + extra_cards) / oopSize;
3742 }
3743
3744 size_t G1CollectedHeap::cards_scanned() {
3745 return g1_rem_set()->cardsScanned();
3746 }
3747
3748 void
3749 G1CollectedHeap::setup_surviving_young_words() {
3750 assert(_surviving_young_words == NULL, "pre-condition");
3751 uint array_length = g1_policy()->young_cset_region_length();
3752 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3753 if (_surviving_young_words == NULL) {
3754 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3755 "Not enough space for young surv words summary.");
3756 }
3757 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3758 #ifdef ASSERT
3759 for (uint i = 0; i < array_length; ++i) {
3760 assert( _surviving_young_words[i] == 0, "memset above" );
3761 }
3762 #endif // !ASSERT
3763 }
3764
3765 void
3766 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3767 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3768 uint array_length = g1_policy()->young_cset_region_length();
3769 for (uint i = 0; i < array_length; ++i) {
3770 _surviving_young_words[i] += surv_young_words[i];
3771 }
3772 }
3773
3774 void
3775 G1CollectedHeap::cleanup_surviving_young_words() {
3776 guarantee( _surviving_young_words != NULL, "pre-condition" );
3777 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3778 _surviving_young_words = NULL;
3779 }
3780
3781 #ifdef ASSERT
3782 class VerifyCSetClosure: public HeapRegionClosure {
3783 public:
3784 bool doHeapRegion(HeapRegion* hr) {
3785 // Here we check that the CSet region's RSet is ready for parallel
3786 // iteration. The fields that we'll verify are only manipulated
3787 // when the region is part of a CSet and is collected. Afterwards,
3788 // we reset these fields when we clear the region's RSet (when the
3789 // region is freed) so they are ready when the region is
3790 // re-allocated. The only exception to this is if there's an
3791 // evacuation failure and instead of freeing the region we leave
3792 // it in the heap. In that case, we reset these fields during
3793 // evacuation failure handling.
3794 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3795
3796 // Here's a good place to add any other checks we'd like to
3797 // perform on CSet regions.
3798 return false;
3799 }
3800 };
3801 #endif // ASSERT
3802
3803 #if TASKQUEUE_STATS
3804 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3805 st->print_raw_cr("GC Task Stats");
3806 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3807 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3808 }
3809
3810 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3811 print_taskqueue_stats_hdr(st);
3812
3813 TaskQueueStats totals;
3814 const int n = workers() != NULL ? workers()->total_workers() : 1;
3815 for (int i = 0; i < n; ++i) {
3816 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3817 totals += task_queue(i)->stats;
3818 }
3819 st->print_raw("tot "); totals.print(st); st->cr();
3820
3821 DEBUG_ONLY(totals.verify());
3822 }
3823
3824 void G1CollectedHeap::reset_taskqueue_stats() {
3825 const int n = workers() != NULL ? workers()->total_workers() : 1;
3826 for (int i = 0; i < n; ++i) {
3827 task_queue(i)->stats.reset();
3828 }
3829 }
3830 #endif // TASKQUEUE_STATS
3831
3832 void G1CollectedHeap::log_gc_header() {
3833 if (!G1Log::fine()) {
3834 return;
3835 }
3836
3837 gclog_or_tty->date_stamp(PrintGCDateStamps);
3838 gclog_or_tty->stamp(PrintGCTimeStamps);
3839
3840 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3841 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3842 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3843
3844 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3845 }
3846
3847 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3848 if (!G1Log::fine()) {
3849 return;
3850 }
3851
3852 if (G1Log::finer()) {
3853 if (evacuation_failed()) {
3854 gclog_or_tty->print(" (to-space exhausted)");
3855 }
3856 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3857 g1_policy()->phase_times()->note_gc_end();
3858 g1_policy()->phase_times()->print(pause_time_sec);
3859 g1_policy()->print_detailed_heap_transition();
3860 } else {
3861 if (evacuation_failed()) {
3862 gclog_or_tty->print("--");
3863 }
3864 g1_policy()->print_heap_transition();
3865 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3866 }
3867 gclog_or_tty->flush();
3868 }
3869
3870 bool
3871 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3872 assert_at_safepoint(true /* should_be_vm_thread */);
3873 guarantee(!is_gc_active(), "collection is not reentrant");
3874
3875 if (GC_locker::check_active_before_gc()) {
3876 return false;
3877 }
3878
3879 _gc_timer_stw->register_gc_start();
3880
3881 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3882
3883 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3884 ResourceMark rm;
3885
3886 print_heap_before_gc();
3887 trace_heap_before_gc(_gc_tracer_stw);
3888
3889 HRSPhaseSetter x(HRSPhaseEvacuation);
3890 verify_region_sets_optional();
3891 verify_dirty_young_regions();
3892
3893 // This call will decide whether this pause is an initial-mark
3894 // pause. If it is, during_initial_mark_pause() will return true
3895 // for the duration of this pause.
3896 g1_policy()->decide_on_conc_mark_initiation();
3897
3898 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3899 assert(!g1_policy()->during_initial_mark_pause() ||
3900 g1_policy()->gcs_are_young(), "sanity");
3901
3902 // We also do not allow mixed GCs during marking.
3903 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3904
3905 // Record whether this pause is an initial mark. When the current
3906 // thread has completed its logging output and it's safe to signal
3907 // the CM thread, the flag's value in the policy has been reset.
3908 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3909
3910 // Inner scope for scope based logging, timers, and stats collection
3911 {
3912 EvacuationInfo evacuation_info;
3913
3914 if (g1_policy()->during_initial_mark_pause()) {
3915 // We are about to start a marking cycle, so we increment the
3916 // full collection counter.
3917 increment_old_marking_cycles_started();
3918 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3919 }
3920
3921 _gc_tracer_stw->report_yc_type(yc_type());
3922
3923 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3924
3925 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3926 workers()->active_workers() : 1);
3927 double pause_start_sec = os::elapsedTime();
3928 g1_policy()->phase_times()->note_gc_start(active_workers);
3929 log_gc_header();
3930
3931 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3932 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3933
3934 // If the secondary_free_list is not empty, append it to the
3935 // free_list. No need to wait for the cleanup operation to finish;
3936 // the region allocation code will check the secondary_free_list
3937 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3938 // set, skip this step so that the region allocation code has to
3939 // get entries from the secondary_free_list.
3940 if (!G1StressConcRegionFreeing) {
3941 append_secondary_free_list_if_not_empty_with_lock();
3942 }
3943
3944 assert(check_young_list_well_formed(), "young list should be well formed");
3945 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3946 "sanity check");
3947
3948 // Don't dynamically change the number of GC threads this early. A value of
3949 // 0 is used to indicate serial work. When parallel work is done,
3950 // it will be set.
3951
3952 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3953 IsGCActiveMark x;
3954
3955 gc_prologue(false);
3956 increment_total_collections(false /* full gc */);
3957 increment_gc_time_stamp();
3958
3959 verify_before_gc();
3960
3961 COMPILER2_PRESENT(DerivedPointerTable::clear());
3962
3963 // Please see comment in g1CollectedHeap.hpp and
3964 // G1CollectedHeap::ref_processing_init() to see how
3965 // reference processing currently works in G1.
3966
3967 // Enable discovery in the STW reference processor
3968 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3969 true /*verify_no_refs*/);
3970
3971 {
3972 // We want to temporarily turn off discovery by the
3973 // CM ref processor, if necessary, and turn it back on
3974 // on again later if we do. Using a scoped
3975 // NoRefDiscovery object will do this.
3976 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3977
3978 // Forget the current alloc region (we might even choose it to be part
3979 // of the collection set!).
3980 release_mutator_alloc_region();
3981
3982 // We should call this after we retire the mutator alloc
3983 // region(s) so that all the ALLOC / RETIRE events are generated
3984 // before the start GC event.
3985 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3986
3987 // This timing is only used by the ergonomics to handle our pause target.
3988 // It is unclear why this should not include the full pause. We will
3989 // investigate this in CR 7178365.
3990 //
3991 // Preserving the old comment here if that helps the investigation:
3992 //
3993 // The elapsed time induced by the start time below deliberately elides
3994 // the possible verification above.
3995 double sample_start_time_sec = os::elapsedTime();
3996
3997 #if YOUNG_LIST_VERBOSE
3998 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3999 _young_list->print();
4000 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4001 #endif // YOUNG_LIST_VERBOSE
4002
4003 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4004
4005 double scan_wait_start = os::elapsedTime();
4006 // We have to wait until the CM threads finish scanning the
4007 // root regions as it's the only way to ensure that all the
4008 // objects on them have been correctly scanned before we start
4009 // moving them during the GC.
4010 bool waited = _cm->root_regions()->wait_until_scan_finished();
4011 double wait_time_ms = 0.0;
4012 if (waited) {
4013 double scan_wait_end = os::elapsedTime();
4014 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4015 }
4016 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4017
4018 #if YOUNG_LIST_VERBOSE
4019 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4020 _young_list->print();
4021 #endif // YOUNG_LIST_VERBOSE
4022
4023 if (g1_policy()->during_initial_mark_pause()) {
4024 concurrent_mark()->checkpointRootsInitialPre();
4025 }
4026
4027 #if YOUNG_LIST_VERBOSE
4028 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4029 _young_list->print();
4030 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4031 #endif // YOUNG_LIST_VERBOSE
4032
4033 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4034
4035 _cm->note_start_of_gc();
4036 // We should not verify the per-thread SATB buffers given that
4037 // we have not filtered them yet (we'll do so during the
4038 // GC). We also call this after finalize_cset() to
4039 // ensure that the CSet has been finalized.
4040 _cm->verify_no_cset_oops(true /* verify_stacks */,
4041 true /* verify_enqueued_buffers */,
4042 false /* verify_thread_buffers */,
4043 true /* verify_fingers */);
4044
4045 if (_hr_printer.is_active()) {
4046 HeapRegion* hr = g1_policy()->collection_set();
4047 while (hr != NULL) {
4048 G1HRPrinter::RegionType type;
4049 if (!hr->is_young()) {
4050 type = G1HRPrinter::Old;
4051 } else if (hr->is_survivor()) {
4052 type = G1HRPrinter::Survivor;
4053 } else {
4054 type = G1HRPrinter::Eden;
4055 }
4056 _hr_printer.cset(hr);
4057 hr = hr->next_in_collection_set();
4058 }
4059 }
4060
4061 #ifdef ASSERT
4062 VerifyCSetClosure cl;
4063 collection_set_iterate(&cl);
4064 #endif // ASSERT
4065
4066 setup_surviving_young_words();
4067
4068 // Initialize the GC alloc regions.
4069 init_gc_alloc_regions(evacuation_info);
4070
4071 // Actually do the work...
4072 evacuate_collection_set(evacuation_info);
4073
4074 // We do this to mainly verify the per-thread SATB buffers
4075 // (which have been filtered by now) since we didn't verify
4076 // them earlier. No point in re-checking the stacks / enqueued
4077 // buffers given that the CSet has not changed since last time
4078 // we checked.
4079 _cm->verify_no_cset_oops(false /* verify_stacks */,
4080 false /* verify_enqueued_buffers */,
4081 true /* verify_thread_buffers */,
4082 true /* verify_fingers */);
4083
4084 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4085 g1_policy()->clear_collection_set();
4086
4087 cleanup_surviving_young_words();
4088
4089 // Start a new incremental collection set for the next pause.
4090 g1_policy()->start_incremental_cset_building();
4091
4092 // Clear the _cset_fast_test bitmap in anticipation of adding
4093 // regions to the incremental collection set for the next
4094 // evacuation pause.
4095 clear_cset_fast_test();
4096
4097 _young_list->reset_sampled_info();
4098
4099 // Don't check the whole heap at this point as the
4100 // GC alloc regions from this pause have been tagged
4101 // as survivors and moved on to the survivor list.
4102 // Survivor regions will fail the !is_young() check.
4103 assert(check_young_list_empty(false /* check_heap */),
4104 "young list should be empty");
4105
4106 #if YOUNG_LIST_VERBOSE
4107 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4108 _young_list->print();
4109 #endif // YOUNG_LIST_VERBOSE
4110
4111 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4112 _young_list->first_survivor_region(),
4113 _young_list->last_survivor_region());
4114
4115 _young_list->reset_auxilary_lists();
4116
4117 if (evacuation_failed()) {
4118 _summary_bytes_used = recalculate_used();
4119 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4120 for (uint i = 0; i < n_queues; i++) {
4121 if (_evacuation_failed_info_array[i].has_failed()) {
4122 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4123 }
4124 }
4125 } else {
4126 // The "used" of the the collection set have already been subtracted
4127 // when they were freed. Add in the bytes evacuated.
4128 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4129 }
4130
4131 if (g1_policy()->during_initial_mark_pause()) {
4132 // We have to do this before we notify the CM threads that
4133 // they can start working to make sure that all the
4134 // appropriate initialization is done on the CM object.
4135 concurrent_mark()->checkpointRootsInitialPost();
4136 set_marking_started();
4137 // Note that we don't actually trigger the CM thread at
4138 // this point. We do that later when we're sure that
4139 // the current thread has completed its logging output.
4140 }
4141
4142 allocate_dummy_regions();
4143
4144 #if YOUNG_LIST_VERBOSE
4145 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4146 _young_list->print();
4147 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4148 #endif // YOUNG_LIST_VERBOSE
4149
4150 init_mutator_alloc_region();
4151
4152 {
4153 size_t expand_bytes = g1_policy()->expansion_amount();
4154 if (expand_bytes > 0) {
4155 size_t bytes_before = capacity();
4156 // No need for an ergo verbose message here,
4157 // expansion_amount() does this when it returns a value > 0.
4158 if (!expand(expand_bytes)) {
4159 // We failed to expand the heap so let's verify that
4160 // committed/uncommitted amount match the backing store
4161 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4162 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4163 }
4164 }
4165 }
4166
4167 // We redo the verification but now wrt to the new CSet which
4168 // has just got initialized after the previous CSet was freed.
4169 _cm->verify_no_cset_oops(true /* verify_stacks */,
4170 true /* verify_enqueued_buffers */,
4171 true /* verify_thread_buffers */,
4172 true /* verify_fingers */);
4173 _cm->note_end_of_gc();
4174
4175 // This timing is only used by the ergonomics to handle our pause target.
4176 // It is unclear why this should not include the full pause. We will
4177 // investigate this in CR 7178365.
4178 double sample_end_time_sec = os::elapsedTime();
4179 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4180 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4181
4182 MemoryService::track_memory_usage();
4183
4184 // In prepare_for_verify() below we'll need to scan the deferred
4185 // update buffers to bring the RSets up-to-date if
4186 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4187 // the update buffers we'll probably need to scan cards on the
4188 // regions we just allocated to (i.e., the GC alloc
4189 // regions). However, during the last GC we called
4190 // set_saved_mark() on all the GC alloc regions, so card
4191 // scanning might skip the [saved_mark_word()...top()] area of
4192 // those regions (i.e., the area we allocated objects into
4193 // during the last GC). But it shouldn't. Given that
4194 // saved_mark_word() is conditional on whether the GC time stamp
4195 // on the region is current or not, by incrementing the GC time
4196 // stamp here we invalidate all the GC time stamps on all the
4197 // regions and saved_mark_word() will simply return top() for
4198 // all the regions. This is a nicer way of ensuring this rather
4199 // than iterating over the regions and fixing them. In fact, the
4200 // GC time stamp increment here also ensures that
4201 // saved_mark_word() will return top() between pauses, i.e.,
4202 // during concurrent refinement. So we don't need the
4203 // is_gc_active() check to decided which top to use when
4204 // scanning cards (see CR 7039627).
4205 increment_gc_time_stamp();
4206
4207 verify_after_gc();
4208
4209 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4210 ref_processor_stw()->verify_no_references_recorded();
4211
4212 // CM reference discovery will be re-enabled if necessary.
4213 }
4214
4215 // We should do this after we potentially expand the heap so
4216 // that all the COMMIT events are generated before the end GC
4217 // event, and after we retire the GC alloc regions so that all
4218 // RETIRE events are generated before the end GC event.
4219 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4220
4221 if (mark_in_progress()) {
4222 concurrent_mark()->update_g1_committed();
4223 }
4224
4225 #ifdef TRACESPINNING
4226 ParallelTaskTerminator::print_termination_counts();
4227 #endif
4228
4229 gc_epilogue(false);
4230 }
4231
4232 // Print the remainder of the GC log output.
4233 log_gc_footer(os::elapsedTime() - pause_start_sec);
4234
4235 // It is not yet to safe to tell the concurrent mark to
4236 // start as we have some optional output below. We don't want the
4237 // output from the concurrent mark thread interfering with this
4238 // logging output either.
4239
4240 _hrs.verify_optional();
4241 verify_region_sets_optional();
4242
4243 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4244 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4245
4246 print_heap_after_gc();
4247 trace_heap_after_gc(_gc_tracer_stw);
4248
4249 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4250 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4251 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4252 // before any GC notifications are raised.
4253 g1mm()->update_sizes();
4254
4255 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4256 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4257 _gc_timer_stw->register_gc_end();
4258 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4259 }
4260 // It should now be safe to tell the concurrent mark thread to start
4261 // without its logging output interfering with the logging output
4262 // that came from the pause.
4263
4264 if (should_start_conc_mark) {
4265 // CAUTION: after the doConcurrentMark() call below,
4266 // the concurrent marking thread(s) could be running
4267 // concurrently with us. Make sure that anything after
4268 // this point does not assume that we are the only GC thread
4269 // running. Note: of course, the actual marking work will
4270 // not start until the safepoint itself is released in
4271 // ConcurrentGCThread::safepoint_desynchronize().
4272 doConcurrentMark();
4273 }
4274
4275 return true;
4276 }
4277
4278 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4279 {
4280 size_t gclab_word_size;
4281 switch (purpose) {
4282 case GCAllocForSurvived:
4283 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4284 break;
4285 case GCAllocForTenured:
4286 gclab_word_size = _old_plab_stats.desired_plab_sz();
4287 break;
4288 default:
4289 assert(false, "unknown GCAllocPurpose");
4290 gclab_word_size = _old_plab_stats.desired_plab_sz();
4291 break;
4292 }
4293
4294 // Prevent humongous PLAB sizes for two reasons:
4295 // * PLABs are allocated using a similar paths as oops, but should
4296 // never be in a humongous region
4297 // * Allowing humongous PLABs needlessly churns the region free lists
4298 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4299 }
4300
4301 void G1CollectedHeap::init_mutator_alloc_region() {
4302 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4303 _mutator_alloc_region.init();
4304 }
4305
4306 void G1CollectedHeap::release_mutator_alloc_region() {
4307 _mutator_alloc_region.release();
4308 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4309 }
4310
4311 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4312 assert_at_safepoint(true /* should_be_vm_thread */);
4313
4314 _survivor_gc_alloc_region.init();
4315 _old_gc_alloc_region.init();
4316 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4317 _retained_old_gc_alloc_region = NULL;
4318
4319 // We will discard the current GC alloc region if:
4320 // a) it's in the collection set (it can happen!),
4321 // b) it's already full (no point in using it),
4322 // c) it's empty (this means that it was emptied during
4323 // a cleanup and it should be on the free list now), or
4324 // d) it's humongous (this means that it was emptied
4325 // during a cleanup and was added to the free list, but
4326 // has been subsequently used to allocate a humongous
4327 // object that may be less than the region size).
4328 if (retained_region != NULL &&
4329 !retained_region->in_collection_set() &&
4330 !(retained_region->top() == retained_region->end()) &&
4331 !retained_region->is_empty() &&
4332 !retained_region->isHumongous()) {
4333 retained_region->set_saved_mark();
4334 // The retained region was added to the old region set when it was
4335 // retired. We have to remove it now, since we don't allow regions
4336 // we allocate to in the region sets. We'll re-add it later, when
4337 // it's retired again.
4338 _old_set.remove(retained_region);
4339 bool during_im = g1_policy()->during_initial_mark_pause();
4340 retained_region->note_start_of_copying(during_im);
4341 _old_gc_alloc_region.set(retained_region);
4342 _hr_printer.reuse(retained_region);
4343 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4344 }
4345 }
4346
4347 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4348 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4349 _old_gc_alloc_region.count());
4350 _survivor_gc_alloc_region.release();
4351 // If we have an old GC alloc region to release, we'll save it in
4352 // _retained_old_gc_alloc_region. If we don't
4353 // _retained_old_gc_alloc_region will become NULL. This is what we
4354 // want either way so no reason to check explicitly for either
4355 // condition.
4356 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4357
4358 if (ResizePLAB) {
4359 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4360 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4361 }
4362 }
4363
4364 void G1CollectedHeap::abandon_gc_alloc_regions() {
4365 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4366 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4367 _retained_old_gc_alloc_region = NULL;
4368 }
4369
4370 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4371 _drain_in_progress = false;
4372 set_evac_failure_closure(cl);
4373 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4374 }
4375
4376 void G1CollectedHeap::finalize_for_evac_failure() {
4377 assert(_evac_failure_scan_stack != NULL &&
4378 _evac_failure_scan_stack->length() == 0,
4379 "Postcondition");
4380 assert(!_drain_in_progress, "Postcondition");
4381 delete _evac_failure_scan_stack;
4382 _evac_failure_scan_stack = NULL;
4383 }
4384
4385 void G1CollectedHeap::remove_self_forwarding_pointers() {
4386 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4387
4388 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4389
4390 if (G1CollectedHeap::use_parallel_gc_threads()) {
4391 set_par_threads();
4392 workers()->run_task(&rsfp_task);
4393 set_par_threads(0);
4394 } else {
4395 rsfp_task.work(0);
4396 }
4397
4398 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4399
4400 // Reset the claim values in the regions in the collection set.
4401 reset_cset_heap_region_claim_values();
4402
4403 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4404
4405 // Now restore saved marks, if any.
4406 assert(_objs_with_preserved_marks.size() ==
4407 _preserved_marks_of_objs.size(), "Both or none.");
4408 while (!_objs_with_preserved_marks.is_empty()) {
4409 oop obj = _objs_with_preserved_marks.pop();
4410 markOop m = _preserved_marks_of_objs.pop();
4411 obj->set_mark(m);
4412 }
4413 _objs_with_preserved_marks.clear(true);
4414 _preserved_marks_of_objs.clear(true);
4415 }
4416
4417 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4418 _evac_failure_scan_stack->push(obj);
4419 }
4420
4421 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4422 assert(_evac_failure_scan_stack != NULL, "precondition");
4423
4424 while (_evac_failure_scan_stack->length() > 0) {
4425 oop obj = _evac_failure_scan_stack->pop();
4426 _evac_failure_closure->set_region(heap_region_containing(obj));
4427 obj->oop_iterate_backwards(_evac_failure_closure);
4428 }
4429 }
4430
4431 oop
4432 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4433 oop old) {
4434 assert(obj_in_cs(old),
4435 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4436 (HeapWord*) old));
4437 markOop m = old->mark();
4438 oop forward_ptr = old->forward_to_atomic(old);
4439 if (forward_ptr == NULL) {
4440 // Forward-to-self succeeded.
4441 assert(_par_scan_state != NULL, "par scan state");
4442 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4443 uint queue_num = _par_scan_state->queue_num();
4444
4445 _evacuation_failed = true;
4446 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4447 if (_evac_failure_closure != cl) {
4448 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4449 assert(!_drain_in_progress,
4450 "Should only be true while someone holds the lock.");
4451 // Set the global evac-failure closure to the current thread's.
4452 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4453 set_evac_failure_closure(cl);
4454 // Now do the common part.
4455 handle_evacuation_failure_common(old, m);
4456 // Reset to NULL.
4457 set_evac_failure_closure(NULL);
4458 } else {
4459 // The lock is already held, and this is recursive.
4460 assert(_drain_in_progress, "This should only be the recursive case.");
4461 handle_evacuation_failure_common(old, m);
4462 }
4463 return old;
4464 } else {
4465 // Forward-to-self failed. Either someone else managed to allocate
4466 // space for this object (old != forward_ptr) or they beat us in
4467 // self-forwarding it (old == forward_ptr).
4468 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4469 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4470 "should not be in the CSet",
4471 (HeapWord*) old, (HeapWord*) forward_ptr));
4472 return forward_ptr;
4473 }
4474 }
4475
4476 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4477 preserve_mark_if_necessary(old, m);
4478
4479 HeapRegion* r = heap_region_containing(old);
4480 if (!r->evacuation_failed()) {
4481 r->set_evacuation_failed(true);
4482 _hr_printer.evac_failure(r);
4483 }
4484
4485 push_on_evac_failure_scan_stack(old);
4486
4487 if (!_drain_in_progress) {
4488 // prevent recursion in copy_to_survivor_space()
4489 _drain_in_progress = true;
4490 drain_evac_failure_scan_stack();
4491 _drain_in_progress = false;
4492 }
4493 }
4494
4495 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4496 assert(evacuation_failed(), "Oversaving!");
4497 // We want to call the "for_promotion_failure" version only in the
4498 // case of a promotion failure.
4499 if (m->must_be_preserved_for_promotion_failure(obj)) {
4500 _objs_with_preserved_marks.push(obj);
4501 _preserved_marks_of_objs.push(m);
4502 }
4503 }
4504
4505 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4506 size_t word_size) {
4507 if (purpose == GCAllocForSurvived) {
4508 HeapWord* result = survivor_attempt_allocation(word_size);
4509 if (result != NULL) {
4510 return result;
4511 } else {
4512 // Let's try to allocate in the old gen in case we can fit the
4513 // object there.
4514 return old_attempt_allocation(word_size);
4515 }
4516 } else {
4517 assert(purpose == GCAllocForTenured, "sanity");
4518 HeapWord* result = old_attempt_allocation(word_size);
4519 if (result != NULL) {
4520 return result;
4521 } else {
4522 // Let's try to allocate in the survivors in case we can fit the
4523 // object there.
4524 return survivor_attempt_allocation(word_size);
4525 }
4526 }
4527
4528 ShouldNotReachHere();
4529 // Trying to keep some compilers happy.
4530 return NULL;
4531 }
4532
4533 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4534 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4535
4536 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4537 : _g1h(g1h),
4538 _refs(g1h->task_queue(queue_num)),
4539 _dcq(&g1h->dirty_card_queue_set()),
4540 _ct_bs(g1h->g1_barrier_set()),
4541 _g1_rem(g1h->g1_rem_set()),
4542 _hash_seed(17), _queue_num(queue_num),
4543 _term_attempts(0),
4544 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4545 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4546 _age_table(false),
4547 _strong_roots_time(0), _term_time(0),
4548 _alloc_buffer_waste(0), _undo_waste(0) {
4549 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4550 // we "sacrifice" entry 0 to keep track of surviving bytes for
4551 // non-young regions (where the age is -1)
4552 // We also add a few elements at the beginning and at the end in
4553 // an attempt to eliminate cache contention
4554 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4555 uint array_length = PADDING_ELEM_NUM +
4556 real_length +
4557 PADDING_ELEM_NUM;
4558 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4559 if (_surviving_young_words_base == NULL)
4560 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4561 "Not enough space for young surv histo.");
4562 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4563 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4564
4565 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4566 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4567
4568 _start = os::elapsedTime();
4569 }
4570
4571 void
4572 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4573 {
4574 st->print_raw_cr("GC Termination Stats");
4575 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4576 " ------waste (KiB)------");
4577 st->print_raw_cr("thr ms ms % ms % attempts"
4578 " total alloc undo");
4579 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4580 " ------- ------- -------");
4581 }
4582
4583 void
4584 G1ParScanThreadState::print_termination_stats(int i,
4585 outputStream* const st) const
4586 {
4587 const double elapsed_ms = elapsed_time() * 1000.0;
4588 const double s_roots_ms = strong_roots_time() * 1000.0;
4589 const double term_ms = term_time() * 1000.0;
4590 st->print_cr("%3d %9.2f %9.2f %6.2f "
4591 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4592 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4593 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4594 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4595 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4596 alloc_buffer_waste() * HeapWordSize / K,
4597 undo_waste() * HeapWordSize / K);
4598 }
4599
4600 #ifdef ASSERT
4601 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4602 assert(ref != NULL, "invariant");
4603 assert(UseCompressedOops, "sanity");
4604 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4605 oop p = oopDesc::load_decode_heap_oop(ref);
4606 assert(_g1h->is_in_g1_reserved(p),
4607 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4608 return true;
4609 }
4610
4611 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4612 assert(ref != NULL, "invariant");
4613 if (has_partial_array_mask(ref)) {
4614 // Must be in the collection set--it's already been copied.
4615 oop p = clear_partial_array_mask(ref);
4616 assert(_g1h->obj_in_cs(p),
4617 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4618 } else {
4619 oop p = oopDesc::load_decode_heap_oop(ref);
4620 assert(_g1h->is_in_g1_reserved(p),
4621 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4622 }
4623 return true;
4624 }
4625
4626 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4627 if (ref.is_narrow()) {
4628 return verify_ref((narrowOop*) ref);
4629 } else {
4630 return verify_ref((oop*) ref);
4631 }
4632 }
4633 #endif // ASSERT
4634
4635 void G1ParScanThreadState::trim_queue() {
4636 assert(_evac_cl != NULL, "not set");
4637 assert(_evac_failure_cl != NULL, "not set");
4638 assert(_partial_scan_cl != NULL, "not set");
4639
4640 StarTask ref;
4641 do {
4642 // Drain the overflow stack first, so other threads can steal.
4643 while (refs()->pop_overflow(ref)) {
4644 deal_with_reference(ref);
4645 }
4646
4647 while (refs()->pop_local(ref)) {
4648 deal_with_reference(ref);
4649 }
4650 } while (!refs()->is_empty());
4651 }
4652
4653 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4654 G1ParScanThreadState* par_scan_state) :
4655 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4656 _par_scan_state(par_scan_state),
4657 _worker_id(par_scan_state->queue_num()),
4658 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4659 _mark_in_progress(_g1->mark_in_progress()) { }
4660
4661 template <G1Barrier barrier, bool do_mark_object>
4662 void G1ParCopyClosure<barrier, do_mark_object>::mark_object(oop obj) {
4663 #ifdef ASSERT
4664 HeapRegion* hr = _g1->heap_region_containing(obj);
4665 assert(hr != NULL, "sanity");
4666 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4667 #endif // ASSERT
4668
4669 // We know that the object is not moving so it's safe to read its size.
4670 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4671 }
4672
4673 template <G1Barrier barrier, bool do_mark_object>
4674 void G1ParCopyClosure<barrier, do_mark_object>
4675 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4676 #ifdef ASSERT
4677 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4678 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4679 assert(from_obj != to_obj, "should not be self-forwarded");
4680
4681 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4682 assert(from_hr != NULL, "sanity");
4683 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4684
4685 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4686 assert(to_hr != NULL, "sanity");
4687 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4688 #endif // ASSERT
4689
4690 // The object might be in the process of being copied by another
4691 // worker so we cannot trust that its to-space image is
4692 // well-formed. So we have to read its size from its from-space
4693 // image which we know should not be changing.
4694 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4695 }
4696
4697 template <G1Barrier barrier, bool do_mark_object>
4698 oop G1ParCopyClosure<barrier, do_mark_object>
4699 ::copy_to_survivor_space(oop old) {
4700 size_t word_sz = old->size();
4701 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4702 // +1 to make the -1 indexes valid...
4703 int young_index = from_region->young_index_in_cset()+1;
4704 assert( (from_region->is_young() && young_index > 0) ||
4705 (!from_region->is_young() && young_index == 0), "invariant" );
4706 G1CollectorPolicy* g1p = _g1->g1_policy();
4707 markOop m = old->mark();
4708 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4709 : m->age();
4710 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4711 word_sz);
4712 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4713 #ifndef PRODUCT
4714 // Should this evacuation fail?
4715 if (_g1->evacuation_should_fail()) {
4716 if (obj_ptr != NULL) {
4717 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4718 obj_ptr = NULL;
4719 }
4720 }
4721 #endif // !PRODUCT
4722
4723 if (obj_ptr == NULL) {
4724 // This will either forward-to-self, or detect that someone else has
4725 // installed a forwarding pointer.
4726 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4727 }
4728
4729 oop obj = oop(obj_ptr);
4730
4731 // We're going to allocate linearly, so might as well prefetch ahead.
4732 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4733
4734 oop forward_ptr = old->forward_to_atomic(obj);
4735 if (forward_ptr == NULL) {
4736 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4737 if (g1p->track_object_age(alloc_purpose)) {
4738 // We could simply do obj->incr_age(). However, this causes a
4739 // performance issue. obj->incr_age() will first check whether
4740 // the object has a displaced mark by checking its mark word;
4741 // getting the mark word from the new location of the object
4742 // stalls. So, given that we already have the mark word and we
4743 // are about to install it anyway, it's better to increase the
4744 // age on the mark word, when the object does not have a
4745 // displaced mark word. We're not expecting many objects to have
4746 // a displaced marked word, so that case is not optimized
4747 // further (it could be...) and we simply call obj->incr_age().
4748
4749 if (m->has_displaced_mark_helper()) {
4750 // in this case, we have to install the mark word first,
4751 // otherwise obj looks to be forwarded (the old mark word,
4752 // which contains the forward pointer, was copied)
4753 obj->set_mark(m);
4754 obj->incr_age();
4755 } else {
4756 m = m->incr_age();
4757 obj->set_mark(m);
4758 }
4759 _par_scan_state->age_table()->add(obj, word_sz);
4760 } else {
4761 obj->set_mark(m);
4762 }
4763
4764 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4765 surv_young_words[young_index] += word_sz;
4766
4767 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4768 // We keep track of the next start index in the length field of
4769 // the from-space object. The actual length can be found in the
4770 // length field of the to-space object.
4771 arrayOop(old)->set_length(0);
4772 oop* old_p = set_partial_array_mask(old);
4773 _par_scan_state->push_on_queue(old_p);
4774 } else {
4775 // No point in using the slower heap_region_containing() method,
4776 // given that we know obj is in the heap.
4777 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4778 obj->oop_iterate_backwards(&_scanner);
4779 }
4780 } else {
4781 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4782 obj = forward_ptr;
4783 }
4784 return obj;
4785 }
4786
4787 template <class T>
4788 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4789 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4790 _scanned_klass->record_modified_oops();
4791 }
4792 }
4793
4794 template <G1Barrier barrier, bool do_mark_object>
4795 template <class T>
4796 void G1ParCopyClosure<barrier, do_mark_object>
4797 ::do_oop_work(T* p) {
4798 oop obj = oopDesc::load_decode_heap_oop(p);
4799
4800 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4801
4802 // here the null check is implicit in the cset_fast_test() test
4803 if (_g1->in_cset_fast_test(obj)) {
4804 oop forwardee;
4805 if (obj->is_forwarded()) {
4806 forwardee = obj->forwardee();
4807 } else {
4808 forwardee = copy_to_survivor_space(obj);
4809 }
4810 assert(forwardee != NULL, "forwardee should not be NULL");
4811 oopDesc::encode_store_heap_oop(p, forwardee);
4812 if (do_mark_object && forwardee != obj) {
4813 // If the object is self-forwarded we don't need to explicitly
4814 // mark it, the evacuation failure protocol will do so.
4815 mark_forwarded_object(obj, forwardee);
4816 }
4817
4818 if (barrier == G1BarrierKlass) {
4819 do_klass_barrier(p, forwardee);
4820 }
4821 } else {
4822 // The object is not in collection set. If we're a root scanning
4823 // closure during an initial mark pause (i.e. do_mark_object will
4824 // be true) then attempt to mark the object.
4825 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4826 mark_object(obj);
4827 }
4828 }
4829
4830 if (barrier == G1BarrierEvac && obj != NULL) {
4831 _par_scan_state->update_rs(_from, p, _worker_id);
4832 }
4833 }
4834
4835 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4836 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4837
4838 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4839 assert(has_partial_array_mask(p), "invariant");
4840 oop from_obj = clear_partial_array_mask(p);
4841
4842 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4843 assert(from_obj->is_objArray(), "must be obj array");
4844 objArrayOop from_obj_array = objArrayOop(from_obj);
4845 // We keep track of the next start index in the length field of the
4846 // from-space object.
4847 int next_index = from_obj_array->length();
4848
4849 assert(from_obj->is_forwarded(), "must be forwarded");
4850 oop to_obj = from_obj->forwardee();
4851 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4852 objArrayOop to_obj_array = objArrayOop(to_obj);
4853 // The to-space object contains the real length.
4854 int length = to_obj_array->length();
4855 assert(0 <= next_index && next_index < length,
4856 err_msg("invariant, next index: %d, length: %d", next_index, length));
4857
4858 int start = next_index;
4859 int end = length;
4860 int remainder = end - start;
4861 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4862 if (remainder > 2 * ParGCArrayScanChunk) {
4863 end = start + ParGCArrayScanChunk;
4864 from_obj_array->set_length(end);
4865 // Push the remainder before we process the range in case another
4866 // worker has run out of things to do and can steal it.
4867 oop* from_obj_p = set_partial_array_mask(from_obj);
4868 _par_scan_state->push_on_queue(from_obj_p);
4869 } else {
4870 assert(length == end, "sanity");
4871 // We'll process the final range for this object. Restore the length
4872 // so that the heap remains parsable in case of evacuation failure.
4873 from_obj_array->set_length(end);
4874 }
4875 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4876 // Process indexes [start,end). It will also process the header
4877 // along with the first chunk (i.e., the chunk with start == 0).
4878 // Note that at this point the length field of to_obj_array is not
4879 // correct given that we are using it to keep track of the next
4880 // start index. oop_iterate_range() (thankfully!) ignores the length
4881 // field and only relies on the start / end parameters. It does
4882 // however return the size of the object which will be incorrect. So
4883 // we have to ignore it even if we wanted to use it.
4884 to_obj_array->oop_iterate_range(&_scanner, start, end);
4885 }
4886
4887 class G1ParEvacuateFollowersClosure : public VoidClosure {
4888 protected:
4889 G1CollectedHeap* _g1h;
4890 G1ParScanThreadState* _par_scan_state;
4891 RefToScanQueueSet* _queues;
4892 ParallelTaskTerminator* _terminator;
4893
4894 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4895 RefToScanQueueSet* queues() { return _queues; }
4896 ParallelTaskTerminator* terminator() { return _terminator; }
4897
4898 public:
4899 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4900 G1ParScanThreadState* par_scan_state,
4901 RefToScanQueueSet* queues,
4902 ParallelTaskTerminator* terminator)
4903 : _g1h(g1h), _par_scan_state(par_scan_state),
4904 _queues(queues), _terminator(terminator) {}
4905
4906 void do_void();
4907
4908 private:
4909 inline bool offer_termination();
4910 };
4911
4912 bool G1ParEvacuateFollowersClosure::offer_termination() {
4913 G1ParScanThreadState* const pss = par_scan_state();
4914 pss->start_term_time();
4915 const bool res = terminator()->offer_termination();
4916 pss->end_term_time();
4917 return res;
4918 }
4919
4920 void G1ParEvacuateFollowersClosure::do_void() {
4921 StarTask stolen_task;
4922 G1ParScanThreadState* const pss = par_scan_state();
4923 pss->trim_queue();
4924
4925 do {
4926 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4927 assert(pss->verify_task(stolen_task), "sanity");
4928 if (stolen_task.is_narrow()) {
4929 pss->deal_with_reference((narrowOop*) stolen_task);
4930 } else {
4931 pss->deal_with_reference((oop*) stolen_task);
4932 }
4933
4934 // We've just processed a reference and we might have made
4935 // available new entries on the queues. So we have to make sure
4936 // we drain the queues as necessary.
4937 pss->trim_queue();
4938 }
4939 } while (!offer_termination());
4940
4941 pss->retire_alloc_buffers();
4942 }
4943
4944 class G1KlassScanClosure : public KlassClosure {
4945 G1ParCopyHelper* _closure;
4946 bool _process_only_dirty;
4947 int _count;
4948 public:
4949 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4950 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4951 void do_klass(Klass* klass) {
4952 // If the klass has not been dirtied we know that there's
4953 // no references into the young gen and we can skip it.
4954 if (!_process_only_dirty || klass->has_modified_oops()) {
4955 // Clean the klass since we're going to scavenge all the metadata.
4956 klass->clear_modified_oops();
4957
4958 // Tell the closure that this klass is the Klass to scavenge
4959 // and is the one to dirty if oops are left pointing into the young gen.
4960 _closure->set_scanned_klass(klass);
4961
4962 klass->oops_do(_closure);
4963
4964 _closure->set_scanned_klass(NULL);
4965 }
4966 _count++;
4967 }
4968 };
4969
4970 class G1ParTask : public AbstractGangTask {
4971 protected:
4972 G1CollectedHeap* _g1h;
4973 RefToScanQueueSet *_queues;
4974 ParallelTaskTerminator _terminator;
4975 uint _n_workers;
4976
4977 Mutex _stats_lock;
4978 Mutex* stats_lock() { return &_stats_lock; }
4979
4980 size_t getNCards() {
4981 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4982 / G1BlockOffsetSharedArray::N_bytes;
4983 }
4984
4985 public:
4986 G1ParTask(G1CollectedHeap* g1h,
4987 RefToScanQueueSet *task_queues)
4988 : AbstractGangTask("G1 collection"),
4989 _g1h(g1h),
4990 _queues(task_queues),
4991 _terminator(0, _queues),
4992 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4993 {}
4994
4995 RefToScanQueueSet* queues() { return _queues; }
4996
4997 RefToScanQueue *work_queue(int i) {
4998 return queues()->queue(i);
4999 }
5000
5001 ParallelTaskTerminator* terminator() { return &_terminator; }
5002
5003 virtual void set_for_termination(int active_workers) {
5004 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5005 // in the young space (_par_seq_tasks) in the G1 heap
5006 // for SequentialSubTasksDone.
5007 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5008 // both of which need setting by set_n_termination().
5009 _g1h->SharedHeap::set_n_termination(active_workers);
5010 _g1h->set_n_termination(active_workers);
5011 terminator()->reset_for_reuse(active_workers);
5012 _n_workers = active_workers;
5013 }
5014
5015 void work(uint worker_id) {
5016 if (worker_id >= _n_workers) return; // no work needed this round
5017
5018 double start_time_ms = os::elapsedTime() * 1000.0;
5019 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5020
5021 {
5022 ResourceMark rm;
5023 HandleMark hm;
5024
5025 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5026
5027 G1ParScanThreadState pss(_g1h, worker_id);
5028 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5029 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5030 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5031
5032 pss.set_evac_closure(&scan_evac_cl);
5033 pss.set_evac_failure_closure(&evac_failure_cl);
5034 pss.set_partial_scan_closure(&partial_scan_cl);
5035
5036 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5037 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5038
5039 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5040 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5041
5042 bool only_young = _g1h->g1_policy()->gcs_are_young();
5043 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5044 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5045
5046 OopClosure* scan_root_cl = &only_scan_root_cl;
5047 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5048
5049 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5050 // We also need to mark copied objects.
5051 scan_root_cl = &scan_mark_root_cl;
5052 scan_klasses_cl = &scan_mark_klasses_cl_s;
5053 }
5054
5055 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5056
5057 // Don't scan the scavengable methods in the code cache as part
5058 // of strong root scanning. The code roots that point into a
5059 // region in the collection set are scanned when we scan the
5060 // region's RSet.
5061 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5062
5063 pss.start_strong_roots();
5064 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5065 SharedHeap::ScanningOption(so),
5066 scan_root_cl,
5067 &push_heap_rs_cl,
5068 scan_klasses_cl,
5069 worker_id);
5070 pss.end_strong_roots();
5071
5072 {
5073 double start = os::elapsedTime();
5074 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5075 evac.do_void();
5076 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5077 double term_ms = pss.term_time()*1000.0;
5078 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5079 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5080 }
5081 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5082 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5083
5084 if (ParallelGCVerbose) {
5085 MutexLocker x(stats_lock());
5086 pss.print_termination_stats(worker_id);
5087 }
5088
5089 assert(pss.refs()->is_empty(), "should be empty");
5090
5091 // Close the inner scope so that the ResourceMark and HandleMark
5092 // destructors are executed here and are included as part of the
5093 // "GC Worker Time".
5094 }
5095
5096 double end_time_ms = os::elapsedTime() * 1000.0;
5097 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5098 }
5099 };
5100
5101 // *** Common G1 Evacuation Stuff
5102
5103 // This method is run in a GC worker.
5104
5105 void
5106 G1CollectedHeap::
5107 g1_process_strong_roots(bool is_scavenging,
5108 ScanningOption so,
5109 OopClosure* scan_non_heap_roots,
5110 OopsInHeapRegionClosure* scan_rs,
5111 G1KlassScanClosure* scan_klasses,
5112 int worker_i) {
5113
5114 // First scan the strong roots
5115 double ext_roots_start = os::elapsedTime();
5116 double closure_app_time_sec = 0.0;
5117
5118 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5119
5120 assert(so & SO_AllCodeCache || scan_rs != NULL, "must scan code roots somehow");
5121 // Walk the code cache/strong code roots w/o buffering, because StarTask
5122 // cannot handle unaligned oop locations.
5123 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5124
5125 process_strong_roots(false, // no scoping; this is parallel code
5126 so,
5127 &buf_scan_non_heap_roots,
5128 &eager_scan_code_roots,
5129 scan_klasses
5130 );
5131
5132 // Now the CM ref_processor roots.
5133 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5134 // We need to treat the discovered reference lists of the
5135 // concurrent mark ref processor as roots and keep entries
5136 // (which are added by the marking threads) on them live
5137 // until they can be processed at the end of marking.
5138 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5139 }
5140
5141 // Finish up any enqueued closure apps (attributed as object copy time).
5142 buf_scan_non_heap_roots.done();
5143
5144 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5145
5146 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5147
5148 double ext_root_time_ms =
5149 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5150
5151 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5152
5153 // During conc marking we have to filter the per-thread SATB buffers
5154 // to make sure we remove any oops into the CSet (which will show up
5155 // as implicitly live).
5156 double satb_filtering_ms = 0.0;
5157 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5158 if (mark_in_progress()) {
5159 double satb_filter_start = os::elapsedTime();
5160
5161 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5162
5163 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5164 }
5165 }
5166 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5167
5168 // If this is an initial mark pause, and we're not scanning
5169 // the entire code cache, we need to mark the oops in the
5170 // strong code root lists for the regions that are not in
5171 // the collection set.
5172 // Note all threads participate in this set of root tasks.
5173 double mark_strong_code_roots_ms = 0.0;
5174 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5175 double mark_strong_roots_start = os::elapsedTime();
5176 mark_strong_code_roots(worker_i);
5177 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5178 }
5179 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5180
5181 // Now scan the complement of the collection set.
5182 if (scan_rs != NULL) {
5183 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5184 }
5185 _process_strong_tasks->all_tasks_completed();
5186 }
5187
5188 void
5189 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5190 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5191 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5192 }
5193
5194 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5195 private:
5196 BoolObjectClosure* _is_alive;
5197 int _initial_string_table_size;
5198 int _initial_symbol_table_size;
5199
5200 bool _process_strings;
5201 int _strings_processed;
5202 int _strings_removed;
5203
5204 bool _process_symbols;
5205 int _symbols_processed;
5206 int _symbols_removed;
5207 public:
5208 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5209 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5210 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5211 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5212
5213 _initial_string_table_size = StringTable::the_table()->table_size();
5214 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5215 if (process_strings) {
5216 StringTable::clear_parallel_claimed_index();
5217 }
5218 if (process_symbols) {
5219 SymbolTable::clear_parallel_claimed_index();
5220 }
5221 }
5222
5223 ~G1StringSymbolTableUnlinkTask() {
5224 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5225 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5226 StringTable::parallel_claimed_index(), _initial_string_table_size));
5227 guarantee(!_process_strings || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5228 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5229 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5230 }
5231
5232 void work(uint worker_id) {
5233 if (G1CollectedHeap::use_parallel_gc_threads()) {
5234 int strings_processed = 0;
5235 int strings_removed = 0;
5236 int symbols_processed = 0;
5237 int symbols_removed = 0;
5238 if (_process_strings) {
5239 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5240 Atomic::add(strings_processed, &_strings_processed);
5241 Atomic::add(strings_removed, &_strings_removed);
5242 }
5243 if (_process_symbols) {
5244 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5245 Atomic::add(symbols_processed, &_symbols_processed);
5246 Atomic::add(symbols_removed, &_symbols_removed);
5247 }
5248 } else {
5249 if (_process_strings) {
5250 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5251 }
5252 if (_process_symbols) {
5253 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5254 }
5255 }
5256 }
5257
5258 size_t strings_processed() const { return (size_t)_strings_processed; }
5259 size_t strings_removed() const { return (size_t)_strings_removed; }
5260
5261 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5262 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5263 };
5264
5265 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5266 bool process_strings, bool process_symbols) {
5267 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5268 _g1h->workers()->active_workers() : 1);
5269
5270 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5271 if (G1CollectedHeap::use_parallel_gc_threads()) {
5272 set_par_threads(n_workers);
5273 workers()->run_task(&g1_unlink_task);
5274 set_par_threads(0);
5275 } else {
5276 g1_unlink_task.work(0);
5277 }
5278 if (G1TraceStringSymbolTableScrubbing) {
5279 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5280 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5281 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5282 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5283 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5284 }
5285 }
5286
5287 // Weak Reference Processing support
5288
5289 // An always "is_alive" closure that is used to preserve referents.
5290 // If the object is non-null then it's alive. Used in the preservation
5291 // of referent objects that are pointed to by reference objects
5292 // discovered by the CM ref processor.
5293 class G1AlwaysAliveClosure: public BoolObjectClosure {
5294 G1CollectedHeap* _g1;
5295 public:
5296 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5297 bool do_object_b(oop p) {
5298 if (p != NULL) {
5299 return true;
5300 }
5301 return false;
5302 }
5303 };
5304
5305 bool G1STWIsAliveClosure::do_object_b(oop p) {
5306 // An object is reachable if it is outside the collection set,
5307 // or is inside and copied.
5308 return !_g1->obj_in_cs(p) || p->is_forwarded();
5309 }
5310
5311 // Non Copying Keep Alive closure
5312 class G1KeepAliveClosure: public OopClosure {
5313 G1CollectedHeap* _g1;
5314 public:
5315 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5316 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5317 void do_oop( oop* p) {
5318 oop obj = *p;
5319
5320 if (_g1->obj_in_cs(obj)) {
5321 assert( obj->is_forwarded(), "invariant" );
5322 *p = obj->forwardee();
5323 }
5324 }
5325 };
5326
5327 // Copying Keep Alive closure - can be called from both
5328 // serial and parallel code as long as different worker
5329 // threads utilize different G1ParScanThreadState instances
5330 // and different queues.
5331
5332 class G1CopyingKeepAliveClosure: public OopClosure {
5333 G1CollectedHeap* _g1h;
5334 OopClosure* _copy_non_heap_obj_cl;
5335 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5336 G1ParScanThreadState* _par_scan_state;
5337
5338 public:
5339 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5340 OopClosure* non_heap_obj_cl,
5341 OopsInHeapRegionClosure* metadata_obj_cl,
5342 G1ParScanThreadState* pss):
5343 _g1h(g1h),
5344 _copy_non_heap_obj_cl(non_heap_obj_cl),
5345 _copy_metadata_obj_cl(metadata_obj_cl),
5346 _par_scan_state(pss)
5347 {}
5348
5349 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5350 virtual void do_oop( oop* p) { do_oop_work(p); }
5351
5352 template <class T> void do_oop_work(T* p) {
5353 oop obj = oopDesc::load_decode_heap_oop(p);
5354
5355 if (_g1h->obj_in_cs(obj)) {
5356 // If the referent object has been forwarded (either copied
5357 // to a new location or to itself in the event of an
5358 // evacuation failure) then we need to update the reference
5359 // field and, if both reference and referent are in the G1
5360 // heap, update the RSet for the referent.
5361 //
5362 // If the referent has not been forwarded then we have to keep
5363 // it alive by policy. Therefore we have copy the referent.
5364 //
5365 // If the reference field is in the G1 heap then we can push
5366 // on the PSS queue. When the queue is drained (after each
5367 // phase of reference processing) the object and it's followers
5368 // will be copied, the reference field set to point to the
5369 // new location, and the RSet updated. Otherwise we need to
5370 // use the the non-heap or metadata closures directly to copy
5371 // the referent object and update the pointer, while avoiding
5372 // updating the RSet.
5373
5374 if (_g1h->is_in_g1_reserved(p)) {
5375 _par_scan_state->push_on_queue(p);
5376 } else {
5377 assert(!ClassLoaderDataGraph::contains((address)p),
5378 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5379 PTR_FORMAT, p));
5380 _copy_non_heap_obj_cl->do_oop(p);
5381 }
5382 }
5383 }
5384 };
5385
5386 // Serial drain queue closure. Called as the 'complete_gc'
5387 // closure for each discovered list in some of the
5388 // reference processing phases.
5389
5390 class G1STWDrainQueueClosure: public VoidClosure {
5391 protected:
5392 G1CollectedHeap* _g1h;
5393 G1ParScanThreadState* _par_scan_state;
5394
5395 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5396
5397 public:
5398 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5399 _g1h(g1h),
5400 _par_scan_state(pss)
5401 { }
5402
5403 void do_void() {
5404 G1ParScanThreadState* const pss = par_scan_state();
5405 pss->trim_queue();
5406 }
5407 };
5408
5409 // Parallel Reference Processing closures
5410
5411 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5412 // processing during G1 evacuation pauses.
5413
5414 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5415 private:
5416 G1CollectedHeap* _g1h;
5417 RefToScanQueueSet* _queues;
5418 FlexibleWorkGang* _workers;
5419 int _active_workers;
5420
5421 public:
5422 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5423 FlexibleWorkGang* workers,
5424 RefToScanQueueSet *task_queues,
5425 int n_workers) :
5426 _g1h(g1h),
5427 _queues(task_queues),
5428 _workers(workers),
5429 _active_workers(n_workers)
5430 {
5431 assert(n_workers > 0, "shouldn't call this otherwise");
5432 }
5433
5434 // Executes the given task using concurrent marking worker threads.
5435 virtual void execute(ProcessTask& task);
5436 virtual void execute(EnqueueTask& task);
5437 };
5438
5439 // Gang task for possibly parallel reference processing
5440
5441 class G1STWRefProcTaskProxy: public AbstractGangTask {
5442 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5443 ProcessTask& _proc_task;
5444 G1CollectedHeap* _g1h;
5445 RefToScanQueueSet *_task_queues;
5446 ParallelTaskTerminator* _terminator;
5447
5448 public:
5449 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5450 G1CollectedHeap* g1h,
5451 RefToScanQueueSet *task_queues,
5452 ParallelTaskTerminator* terminator) :
5453 AbstractGangTask("Process reference objects in parallel"),
5454 _proc_task(proc_task),
5455 _g1h(g1h),
5456 _task_queues(task_queues),
5457 _terminator(terminator)
5458 {}
5459
5460 virtual void work(uint worker_id) {
5461 // The reference processing task executed by a single worker.
5462 ResourceMark rm;
5463 HandleMark hm;
5464
5465 G1STWIsAliveClosure is_alive(_g1h);
5466
5467 G1ParScanThreadState pss(_g1h, worker_id);
5468
5469 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5470 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5471 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5472
5473 pss.set_evac_closure(&scan_evac_cl);
5474 pss.set_evac_failure_closure(&evac_failure_cl);
5475 pss.set_partial_scan_closure(&partial_scan_cl);
5476
5477 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5478 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5479
5480 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5481 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5482
5483 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5484 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5485
5486 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5487 // We also need to mark copied objects.
5488 copy_non_heap_cl = ©_mark_non_heap_cl;
5489 copy_metadata_cl = ©_mark_metadata_cl;
5490 }
5491
5492 // Keep alive closure.
5493 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5494
5495 // Complete GC closure
5496 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5497
5498 // Call the reference processing task's work routine.
5499 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5500
5501 // Note we cannot assert that the refs array is empty here as not all
5502 // of the processing tasks (specifically phase2 - pp2_work) execute
5503 // the complete_gc closure (which ordinarily would drain the queue) so
5504 // the queue may not be empty.
5505 }
5506 };
5507
5508 // Driver routine for parallel reference processing.
5509 // Creates an instance of the ref processing gang
5510 // task and has the worker threads execute it.
5511 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5512 assert(_workers != NULL, "Need parallel worker threads.");
5513
5514 ParallelTaskTerminator terminator(_active_workers, _queues);
5515 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5516
5517 _g1h->set_par_threads(_active_workers);
5518 _workers->run_task(&proc_task_proxy);
5519 _g1h->set_par_threads(0);
5520 }
5521
5522 // Gang task for parallel reference enqueueing.
5523
5524 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5525 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5526 EnqueueTask& _enq_task;
5527
5528 public:
5529 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5530 AbstractGangTask("Enqueue reference objects in parallel"),
5531 _enq_task(enq_task)
5532 { }
5533
5534 virtual void work(uint worker_id) {
5535 _enq_task.work(worker_id);
5536 }
5537 };
5538
5539 // Driver routine for parallel reference enqueueing.
5540 // Creates an instance of the ref enqueueing gang
5541 // task and has the worker threads execute it.
5542
5543 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5544 assert(_workers != NULL, "Need parallel worker threads.");
5545
5546 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5547
5548 _g1h->set_par_threads(_active_workers);
5549 _workers->run_task(&enq_task_proxy);
5550 _g1h->set_par_threads(0);
5551 }
5552
5553 // End of weak reference support closures
5554
5555 // Abstract task used to preserve (i.e. copy) any referent objects
5556 // that are in the collection set and are pointed to by reference
5557 // objects discovered by the CM ref processor.
5558
5559 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5560 protected:
5561 G1CollectedHeap* _g1h;
5562 RefToScanQueueSet *_queues;
5563 ParallelTaskTerminator _terminator;
5564 uint _n_workers;
5565
5566 public:
5567 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5568 AbstractGangTask("ParPreserveCMReferents"),
5569 _g1h(g1h),
5570 _queues(task_queues),
5571 _terminator(workers, _queues),
5572 _n_workers(workers)
5573 { }
5574
5575 void work(uint worker_id) {
5576 ResourceMark rm;
5577 HandleMark hm;
5578
5579 G1ParScanThreadState pss(_g1h, worker_id);
5580 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5581 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5582 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5583
5584 pss.set_evac_closure(&scan_evac_cl);
5585 pss.set_evac_failure_closure(&evac_failure_cl);
5586 pss.set_partial_scan_closure(&partial_scan_cl);
5587
5588 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5589
5590
5591 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5592 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5593
5594 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5595 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5596
5597 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5598 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5599
5600 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5601 // We also need to mark copied objects.
5602 copy_non_heap_cl = ©_mark_non_heap_cl;
5603 copy_metadata_cl = ©_mark_metadata_cl;
5604 }
5605
5606 // Is alive closure
5607 G1AlwaysAliveClosure always_alive(_g1h);
5608
5609 // Copying keep alive closure. Applied to referent objects that need
5610 // to be copied.
5611 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5612
5613 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5614
5615 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5616 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5617
5618 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5619 // So this must be true - but assert just in case someone decides to
5620 // change the worker ids.
5621 assert(0 <= worker_id && worker_id < limit, "sanity");
5622 assert(!rp->discovery_is_atomic(), "check this code");
5623
5624 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5625 for (uint idx = worker_id; idx < limit; idx += stride) {
5626 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5627
5628 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5629 while (iter.has_next()) {
5630 // Since discovery is not atomic for the CM ref processor, we
5631 // can see some null referent objects.
5632 iter.load_ptrs(DEBUG_ONLY(true));
5633 oop ref = iter.obj();
5634
5635 // This will filter nulls.
5636 if (iter.is_referent_alive()) {
5637 iter.make_referent_alive();
5638 }
5639 iter.move_to_next();
5640 }
5641 }
5642
5643 // Drain the queue - which may cause stealing
5644 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5645 drain_queue.do_void();
5646 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5647 assert(pss.refs()->is_empty(), "should be");
5648 }
5649 };
5650
5651 // Weak Reference processing during an evacuation pause (part 1).
5652 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5653 double ref_proc_start = os::elapsedTime();
5654
5655 ReferenceProcessor* rp = _ref_processor_stw;
5656 assert(rp->discovery_enabled(), "should have been enabled");
5657
5658 // Any reference objects, in the collection set, that were 'discovered'
5659 // by the CM ref processor should have already been copied (either by
5660 // applying the external root copy closure to the discovered lists, or
5661 // by following an RSet entry).
5662 //
5663 // But some of the referents, that are in the collection set, that these
5664 // reference objects point to may not have been copied: the STW ref
5665 // processor would have seen that the reference object had already
5666 // been 'discovered' and would have skipped discovering the reference,
5667 // but would not have treated the reference object as a regular oop.
5668 // As a result the copy closure would not have been applied to the
5669 // referent object.
5670 //
5671 // We need to explicitly copy these referent objects - the references
5672 // will be processed at the end of remarking.
5673 //
5674 // We also need to do this copying before we process the reference
5675 // objects discovered by the STW ref processor in case one of these
5676 // referents points to another object which is also referenced by an
5677 // object discovered by the STW ref processor.
5678
5679 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5680 no_of_gc_workers == workers()->active_workers(),
5681 "Need to reset active GC workers");
5682
5683 set_par_threads(no_of_gc_workers);
5684 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5685 no_of_gc_workers,
5686 _task_queues);
5687
5688 if (G1CollectedHeap::use_parallel_gc_threads()) {
5689 workers()->run_task(&keep_cm_referents);
5690 } else {
5691 keep_cm_referents.work(0);
5692 }
5693
5694 set_par_threads(0);
5695
5696 // Closure to test whether a referent is alive.
5697 G1STWIsAliveClosure is_alive(this);
5698
5699 // Even when parallel reference processing is enabled, the processing
5700 // of JNI refs is serial and performed serially by the current thread
5701 // rather than by a worker. The following PSS will be used for processing
5702 // JNI refs.
5703
5704 // Use only a single queue for this PSS.
5705 G1ParScanThreadState pss(this, 0);
5706
5707 // We do not embed a reference processor in the copying/scanning
5708 // closures while we're actually processing the discovered
5709 // reference objects.
5710 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5711 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5712 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5713
5714 pss.set_evac_closure(&scan_evac_cl);
5715 pss.set_evac_failure_closure(&evac_failure_cl);
5716 pss.set_partial_scan_closure(&partial_scan_cl);
5717
5718 assert(pss.refs()->is_empty(), "pre-condition");
5719
5720 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5721 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5722
5723 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5724 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5725
5726 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5727 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5728
5729 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5730 // We also need to mark copied objects.
5731 copy_non_heap_cl = ©_mark_non_heap_cl;
5732 copy_metadata_cl = ©_mark_metadata_cl;
5733 }
5734
5735 // Keep alive closure.
5736 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5737
5738 // Serial Complete GC closure
5739 G1STWDrainQueueClosure drain_queue(this, &pss);
5740
5741 // Setup the soft refs policy...
5742 rp->setup_policy(false);
5743
5744 ReferenceProcessorStats stats;
5745 if (!rp->processing_is_mt()) {
5746 // Serial reference processing...
5747 stats = rp->process_discovered_references(&is_alive,
5748 &keep_alive,
5749 &drain_queue,
5750 NULL,
5751 _gc_timer_stw);
5752 } else {
5753 // Parallel reference processing
5754 assert(rp->num_q() == no_of_gc_workers, "sanity");
5755 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5756
5757 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5758 stats = rp->process_discovered_references(&is_alive,
5759 &keep_alive,
5760 &drain_queue,
5761 &par_task_executor,
5762 _gc_timer_stw);
5763 }
5764
5765 _gc_tracer_stw->report_gc_reference_stats(stats);
5766 // We have completed copying any necessary live referent objects
5767 // (that were not copied during the actual pause) so we can
5768 // retire any active alloc buffers
5769 pss.retire_alloc_buffers();
5770 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5771
5772 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5773 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5774 }
5775
5776 // Weak Reference processing during an evacuation pause (part 2).
5777 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5778 double ref_enq_start = os::elapsedTime();
5779
5780 ReferenceProcessor* rp = _ref_processor_stw;
5781 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5782
5783 // Now enqueue any remaining on the discovered lists on to
5784 // the pending list.
5785 if (!rp->processing_is_mt()) {
5786 // Serial reference processing...
5787 rp->enqueue_discovered_references();
5788 } else {
5789 // Parallel reference enqueueing
5790
5791 assert(no_of_gc_workers == workers()->active_workers(),
5792 "Need to reset active workers");
5793 assert(rp->num_q() == no_of_gc_workers, "sanity");
5794 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5795
5796 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5797 rp->enqueue_discovered_references(&par_task_executor);
5798 }
5799
5800 rp->verify_no_references_recorded();
5801 assert(!rp->discovery_enabled(), "should have been disabled");
5802
5803 // FIXME
5804 // CM's reference processing also cleans up the string and symbol tables.
5805 // Should we do that here also? We could, but it is a serial operation
5806 // and could significantly increase the pause time.
5807
5808 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5809 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5810 }
5811
5812 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5813 _expand_heap_after_alloc_failure = true;
5814 _evacuation_failed = false;
5815
5816 // Should G1EvacuationFailureALot be in effect for this GC?
5817 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5818
5819 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5820
5821 // Disable the hot card cache.
5822 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5823 hot_card_cache->reset_hot_cache_claimed_index();
5824 hot_card_cache->set_use_cache(false);
5825
5826 uint n_workers;
5827 if (G1CollectedHeap::use_parallel_gc_threads()) {
5828 n_workers =
5829 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5830 workers()->active_workers(),
5831 Threads::number_of_non_daemon_threads());
5832 assert(UseDynamicNumberOfGCThreads ||
5833 n_workers == workers()->total_workers(),
5834 "If not dynamic should be using all the workers");
5835 workers()->set_active_workers(n_workers);
5836 set_par_threads(n_workers);
5837 } else {
5838 assert(n_par_threads() == 0,
5839 "Should be the original non-parallel value");
5840 n_workers = 1;
5841 }
5842
5843 G1ParTask g1_par_task(this, _task_queues);
5844
5845 init_for_evac_failure(NULL);
5846
5847 rem_set()->prepare_for_younger_refs_iterate(true);
5848
5849 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5850 double start_par_time_sec = os::elapsedTime();
5851 double end_par_time_sec;
5852
5853 {
5854 StrongRootsScope srs(this);
5855
5856 if (G1CollectedHeap::use_parallel_gc_threads()) {
5857 // The individual threads will set their evac-failure closures.
5858 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5859 // These tasks use ShareHeap::_process_strong_tasks
5860 assert(UseDynamicNumberOfGCThreads ||
5861 workers()->active_workers() == workers()->total_workers(),
5862 "If not dynamic should be using all the workers");
5863 workers()->run_task(&g1_par_task);
5864 } else {
5865 g1_par_task.set_for_termination(n_workers);
5866 g1_par_task.work(0);
5867 }
5868 end_par_time_sec = os::elapsedTime();
5869
5870 // Closing the inner scope will execute the destructor
5871 // for the StrongRootsScope object. We record the current
5872 // elapsed time before closing the scope so that time
5873 // taken for the SRS destructor is NOT included in the
5874 // reported parallel time.
5875 }
5876
5877 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5878 g1_policy()->phase_times()->record_par_time(par_time_ms);
5879
5880 double code_root_fixup_time_ms =
5881 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5882 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5883
5884 set_par_threads(0);
5885
5886 // Process any discovered reference objects - we have
5887 // to do this _before_ we retire the GC alloc regions
5888 // as we may have to copy some 'reachable' referent
5889 // objects (and their reachable sub-graphs) that were
5890 // not copied during the pause.
5891 process_discovered_references(n_workers);
5892
5893 // Weak root processing.
5894 {
5895 G1STWIsAliveClosure is_alive(this);
5896 G1KeepAliveClosure keep_alive(this);
5897 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5898 }
5899
5900 release_gc_alloc_regions(n_workers, evacuation_info);
5901 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5902
5903 // Reset and re-enable the hot card cache.
5904 // Note the counts for the cards in the regions in the
5905 // collection set are reset when the collection set is freed.
5906 hot_card_cache->reset_hot_cache();
5907 hot_card_cache->set_use_cache(true);
5908
5909 // Migrate the strong code roots attached to each region in
5910 // the collection set. Ideally we would like to do this
5911 // after we have finished the scanning/evacuation of the
5912 // strong code roots for a particular heap region.
5913 migrate_strong_code_roots();
5914
5915 if (g1_policy()->during_initial_mark_pause()) {
5916 // Reset the claim values set during marking the strong code roots
5917 reset_heap_region_claim_values();
5918 }
5919
5920 finalize_for_evac_failure();
5921
5922 if (evacuation_failed()) {
5923 remove_self_forwarding_pointers();
5924
5925 // Reset the G1EvacuationFailureALot counters and flags
5926 // Note: the values are reset only when an actual
5927 // evacuation failure occurs.
5928 NOT_PRODUCT(reset_evacuation_should_fail();)
5929 }
5930
5931 // Enqueue any remaining references remaining on the STW
5932 // reference processor's discovered lists. We need to do
5933 // this after the card table is cleaned (and verified) as
5934 // the act of enqueueing entries on to the pending list
5935 // will log these updates (and dirty their associated
5936 // cards). We need these updates logged to update any
5937 // RSets.
5938 enqueue_discovered_references(n_workers);
5939
5940 if (G1DeferredRSUpdate) {
5941 RedirtyLoggedCardTableEntryFastClosure redirty;
5942 dirty_card_queue_set().set_closure(&redirty);
5943 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5944
5945 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5946 dcq.merge_bufferlists(&dirty_card_queue_set());
5947 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5948 }
5949 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5950 }
5951
5952 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5953 size_t* pre_used,
5954 FreeRegionList* free_list,
5955 OldRegionSet* old_proxy_set,
5956 HumongousRegionSet* humongous_proxy_set,
5957 HRRSCleanupTask* hrrs_cleanup_task,
5958 bool par) {
5959 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5960 if (hr->isHumongous()) {
5961 assert(hr->startsHumongous(), "we should only see starts humongous");
5962 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5963 } else {
5964 _old_set.remove_with_proxy(hr, old_proxy_set);
5965 free_region(hr, pre_used, free_list, par);
5966 }
5967 } else {
5968 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5969 }
5970 }
5971
5972 void G1CollectedHeap::free_region(HeapRegion* hr,
5973 size_t* pre_used,
5974 FreeRegionList* free_list,
5975 bool par) {
5976 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5977 assert(!hr->is_empty(), "the region should not be empty");
5978 assert(free_list != NULL, "pre-condition");
5979
5980 // Clear the card counts for this region.
5981 // Note: we only need to do this if the region is not young
5982 // (since we don't refine cards in young regions).
5983 if (!hr->is_young()) {
5984 _cg1r->hot_card_cache()->reset_card_counts(hr);
5985 }
5986 *pre_used += hr->used();
5987 hr->hr_clear(par, true /* clear_space */);
5988 free_list->add_as_head(hr);
5989 }
5990
5991 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5992 size_t* pre_used,
5993 FreeRegionList* free_list,
5994 HumongousRegionSet* humongous_proxy_set,
5995 bool par) {
5996 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5997 assert(free_list != NULL, "pre-condition");
5998 assert(humongous_proxy_set != NULL, "pre-condition");
5999
6000 size_t hr_used = hr->used();
6001 size_t hr_capacity = hr->capacity();
6002 size_t hr_pre_used = 0;
6003 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
6004 // We need to read this before we make the region non-humongous,
6005 // otherwise the information will be gone.
6006 uint last_index = hr->last_hc_index();
6007 hr->set_notHumongous();
6008 free_region(hr, &hr_pre_used, free_list, par);
6009
6010 uint i = hr->hrs_index() + 1;
6011 while (i < last_index) {
6012 HeapRegion* curr_hr = region_at(i);
6013 assert(curr_hr->continuesHumongous(), "invariant");
6014 curr_hr->set_notHumongous();
6015 free_region(curr_hr, &hr_pre_used, free_list, par);
6016 i += 1;
6017 }
6018 assert(hr_pre_used == hr_used,
6019 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
6020 "should be the same", hr_pre_used, hr_used));
6021 *pre_used += hr_pre_used;
6022 }
6023
6024 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
6025 FreeRegionList* free_list,
6026 OldRegionSet* old_proxy_set,
6027 HumongousRegionSet* humongous_proxy_set,
6028 bool par) {
6029 if (pre_used > 0) {
6030 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
6031 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
6032 assert(_summary_bytes_used >= pre_used,
6033 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
6034 "should be >= pre_used: "SIZE_FORMAT,
6035 _summary_bytes_used, pre_used));
6036 _summary_bytes_used -= pre_used;
6037 }
6038 if (free_list != NULL && !free_list->is_empty()) {
6039 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6040 _free_list.add_as_head(free_list);
6041 }
6042 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
6043 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6044 _old_set.update_from_proxy(old_proxy_set);
6045 }
6046 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
6047 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6048 _humongous_set.update_from_proxy(humongous_proxy_set);
6049 }
6050 }
6051
6052 class G1ParCleanupCTTask : public AbstractGangTask {
6053 G1SATBCardTableModRefBS* _ct_bs;
6054 G1CollectedHeap* _g1h;
6055 HeapRegion* volatile _su_head;
6056 public:
6057 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6058 G1CollectedHeap* g1h) :
6059 AbstractGangTask("G1 Par Cleanup CT Task"),
6060 _ct_bs(ct_bs), _g1h(g1h) { }
6061
6062 void work(uint worker_id) {
6063 HeapRegion* r;
6064 while (r = _g1h->pop_dirty_cards_region()) {
6065 clear_cards(r);
6066 }
6067 }
6068
6069 void clear_cards(HeapRegion* r) {
6070 // Cards of the survivors should have already been dirtied.
6071 if (!r->is_survivor()) {
6072 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6073 }
6074 }
6075 };
6076
6077 #ifndef PRODUCT
6078 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6079 G1CollectedHeap* _g1h;
6080 G1SATBCardTableModRefBS* _ct_bs;
6081 public:
6082 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6083 : _g1h(g1h), _ct_bs(ct_bs) { }
6084 virtual bool doHeapRegion(HeapRegion* r) {
6085 if (r->is_survivor()) {
6086 _g1h->verify_dirty_region(r);
6087 } else {
6088 _g1h->verify_not_dirty_region(r);
6089 }
6090 return false;
6091 }
6092 };
6093
6094 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6095 // All of the region should be clean.
6096 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6097 MemRegion mr(hr->bottom(), hr->end());
6098 ct_bs->verify_not_dirty_region(mr);
6099 }
6100
6101 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6102 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6103 // dirty allocated blocks as they allocate them. The thread that
6104 // retires each region and replaces it with a new one will do a
6105 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6106 // not dirty that area (one less thing to have to do while holding
6107 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6108 // is dirty.
6109 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6110 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6111 if (hr->is_young()) {
6112 ct_bs->verify_g1_young_region(mr);
6113 } else {
6114 ct_bs->verify_dirty_region(mr);
6115 }
6116 }
6117
6118 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6119 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6120 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6121 verify_dirty_region(hr);
6122 }
6123 }
6124
6125 void G1CollectedHeap::verify_dirty_young_regions() {
6126 verify_dirty_young_list(_young_list->first_region());
6127 }
6128 #endif
6129
6130 void G1CollectedHeap::cleanUpCardTable() {
6131 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6132 double start = os::elapsedTime();
6133
6134 {
6135 // Iterate over the dirty cards region list.
6136 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6137
6138 if (G1CollectedHeap::use_parallel_gc_threads()) {
6139 set_par_threads();
6140 workers()->run_task(&cleanup_task);
6141 set_par_threads(0);
6142 } else {
6143 while (_dirty_cards_region_list) {
6144 HeapRegion* r = _dirty_cards_region_list;
6145 cleanup_task.clear_cards(r);
6146 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6147 if (_dirty_cards_region_list == r) {
6148 // The last region.
6149 _dirty_cards_region_list = NULL;
6150 }
6151 r->set_next_dirty_cards_region(NULL);
6152 }
6153 }
6154 #ifndef PRODUCT
6155 if (G1VerifyCTCleanup || VerifyAfterGC) {
6156 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6157 heap_region_iterate(&cleanup_verifier);
6158 }
6159 #endif
6160 }
6161
6162 double elapsed = os::elapsedTime() - start;
6163 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6164 }
6165
6166 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6167 size_t pre_used = 0;
6168 FreeRegionList local_free_list("Local List for CSet Freeing");
6169
6170 double young_time_ms = 0.0;
6171 double non_young_time_ms = 0.0;
6172
6173 // Since the collection set is a superset of the the young list,
6174 // all we need to do to clear the young list is clear its
6175 // head and length, and unlink any young regions in the code below
6176 _young_list->clear();
6177
6178 G1CollectorPolicy* policy = g1_policy();
6179
6180 double start_sec = os::elapsedTime();
6181 bool non_young = true;
6182
6183 HeapRegion* cur = cs_head;
6184 int age_bound = -1;
6185 size_t rs_lengths = 0;
6186
6187 while (cur != NULL) {
6188 assert(!is_on_master_free_list(cur), "sanity");
6189 if (non_young) {
6190 if (cur->is_young()) {
6191 double end_sec = os::elapsedTime();
6192 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6193 non_young_time_ms += elapsed_ms;
6194
6195 start_sec = os::elapsedTime();
6196 non_young = false;
6197 }
6198 } else {
6199 if (!cur->is_young()) {
6200 double end_sec = os::elapsedTime();
6201 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6202 young_time_ms += elapsed_ms;
6203
6204 start_sec = os::elapsedTime();
6205 non_young = true;
6206 }
6207 }
6208
6209 rs_lengths += cur->rem_set()->occupied();
6210
6211 HeapRegion* next = cur->next_in_collection_set();
6212 assert(cur->in_collection_set(), "bad CS");
6213 cur->set_next_in_collection_set(NULL);
6214 cur->set_in_collection_set(false);
6215
6216 if (cur->is_young()) {
6217 int index = cur->young_index_in_cset();
6218 assert(index != -1, "invariant");
6219 assert((uint) index < policy->young_cset_region_length(), "invariant");
6220 size_t words_survived = _surviving_young_words[index];
6221 cur->record_surv_words_in_group(words_survived);
6222
6223 // At this point the we have 'popped' cur from the collection set
6224 // (linked via next_in_collection_set()) but it is still in the
6225 // young list (linked via next_young_region()). Clear the
6226 // _next_young_region field.
6227 cur->set_next_young_region(NULL);
6228 } else {
6229 int index = cur->young_index_in_cset();
6230 assert(index == -1, "invariant");
6231 }
6232
6233 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6234 (!cur->is_young() && cur->young_index_in_cset() == -1),
6235 "invariant" );
6236
6237 if (!cur->evacuation_failed()) {
6238 MemRegion used_mr = cur->used_region();
6239
6240 // And the region is empty.
6241 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6242 free_region(cur, &pre_used, &local_free_list, false /* par */);
6243 } else {
6244 cur->uninstall_surv_rate_group();
6245 if (cur->is_young()) {
6246 cur->set_young_index_in_cset(-1);
6247 }
6248 cur->set_not_young();
6249 cur->set_evacuation_failed(false);
6250 // The region is now considered to be old.
6251 _old_set.add(cur);
6252 evacuation_info.increment_collectionset_used_after(cur->used());
6253 }
6254 cur = next;
6255 }
6256
6257 evacuation_info.set_regions_freed(local_free_list.length());
6258 policy->record_max_rs_lengths(rs_lengths);
6259 policy->cset_regions_freed();
6260
6261 double end_sec = os::elapsedTime();
6262 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6263
6264 if (non_young) {
6265 non_young_time_ms += elapsed_ms;
6266 } else {
6267 young_time_ms += elapsed_ms;
6268 }
6269
6270 update_sets_after_freeing_regions(pre_used, &local_free_list,
6271 NULL /* old_proxy_set */,
6272 NULL /* humongous_proxy_set */,
6273 false /* par */);
6274 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6275 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6276 }
6277
6278 // This routine is similar to the above but does not record
6279 // any policy statistics or update free lists; we are abandoning
6280 // the current incremental collection set in preparation of a
6281 // full collection. After the full GC we will start to build up
6282 // the incremental collection set again.
6283 // This is only called when we're doing a full collection
6284 // and is immediately followed by the tearing down of the young list.
6285
6286 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6287 HeapRegion* cur = cs_head;
6288
6289 while (cur != NULL) {
6290 HeapRegion* next = cur->next_in_collection_set();
6291 assert(cur->in_collection_set(), "bad CS");
6292 cur->set_next_in_collection_set(NULL);
6293 cur->set_in_collection_set(false);
6294 cur->set_young_index_in_cset(-1);
6295 cur = next;
6296 }
6297 }
6298
6299 void G1CollectedHeap::set_free_regions_coming() {
6300 if (G1ConcRegionFreeingVerbose) {
6301 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6302 "setting free regions coming");
6303 }
6304
6305 assert(!free_regions_coming(), "pre-condition");
6306 _free_regions_coming = true;
6307 }
6308
6309 void G1CollectedHeap::reset_free_regions_coming() {
6310 assert(free_regions_coming(), "pre-condition");
6311
6312 {
6313 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6314 _free_regions_coming = false;
6315 SecondaryFreeList_lock->notify_all();
6316 }
6317
6318 if (G1ConcRegionFreeingVerbose) {
6319 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6320 "reset free regions coming");
6321 }
6322 }
6323
6324 void G1CollectedHeap::wait_while_free_regions_coming() {
6325 // Most of the time we won't have to wait, so let's do a quick test
6326 // first before we take the lock.
6327 if (!free_regions_coming()) {
6328 return;
6329 }
6330
6331 if (G1ConcRegionFreeingVerbose) {
6332 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6333 "waiting for free regions");
6334 }
6335
6336 {
6337 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6338 while (free_regions_coming()) {
6339 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6340 }
6341 }
6342
6343 if (G1ConcRegionFreeingVerbose) {
6344 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6345 "done waiting for free regions");
6346 }
6347 }
6348
6349 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6350 assert(heap_lock_held_for_gc(),
6351 "the heap lock should already be held by or for this thread");
6352 _young_list->push_region(hr);
6353 }
6354
6355 class NoYoungRegionsClosure: public HeapRegionClosure {
6356 private:
6357 bool _success;
6358 public:
6359 NoYoungRegionsClosure() : _success(true) { }
6360 bool doHeapRegion(HeapRegion* r) {
6361 if (r->is_young()) {
6362 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6363 r->bottom(), r->end());
6364 _success = false;
6365 }
6366 return false;
6367 }
6368 bool success() { return _success; }
6369 };
6370
6371 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6372 bool ret = _young_list->check_list_empty(check_sample);
6373
6374 if (check_heap) {
6375 NoYoungRegionsClosure closure;
6376 heap_region_iterate(&closure);
6377 ret = ret && closure.success();
6378 }
6379
6380 return ret;
6381 }
6382
6383 class TearDownRegionSetsClosure : public HeapRegionClosure {
6384 private:
6385 OldRegionSet *_old_set;
6386
6387 public:
6388 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6389
6390 bool doHeapRegion(HeapRegion* r) {
6391 if (r->is_empty()) {
6392 // We ignore empty regions, we'll empty the free list afterwards
6393 } else if (r->is_young()) {
6394 // We ignore young regions, we'll empty the young list afterwards
6395 } else if (r->isHumongous()) {
6396 // We ignore humongous regions, we're not tearing down the
6397 // humongous region set
6398 } else {
6399 // The rest should be old
6400 _old_set->remove(r);
6401 }
6402 return false;
6403 }
6404
6405 ~TearDownRegionSetsClosure() {
6406 assert(_old_set->is_empty(), "post-condition");
6407 }
6408 };
6409
6410 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6411 assert_at_safepoint(true /* should_be_vm_thread */);
6412
6413 if (!free_list_only) {
6414 TearDownRegionSetsClosure cl(&_old_set);
6415 heap_region_iterate(&cl);
6416
6417 // Need to do this after the heap iteration to be able to
6418 // recognize the young regions and ignore them during the iteration.
6419 _young_list->empty_list();
6420 }
6421 _free_list.remove_all();
6422 }
6423
6424 class RebuildRegionSetsClosure : public HeapRegionClosure {
6425 private:
6426 bool _free_list_only;
6427 OldRegionSet* _old_set;
6428 FreeRegionList* _free_list;
6429 size_t _total_used;
6430
6431 public:
6432 RebuildRegionSetsClosure(bool free_list_only,
6433 OldRegionSet* old_set, FreeRegionList* free_list) :
6434 _free_list_only(free_list_only),
6435 _old_set(old_set), _free_list(free_list), _total_used(0) {
6436 assert(_free_list->is_empty(), "pre-condition");
6437 if (!free_list_only) {
6438 assert(_old_set->is_empty(), "pre-condition");
6439 }
6440 }
6441
6442 bool doHeapRegion(HeapRegion* r) {
6443 if (r->continuesHumongous()) {
6444 return false;
6445 }
6446
6447 if (r->is_empty()) {
6448 // Add free regions to the free list
6449 _free_list->add_as_tail(r);
6450 } else if (!_free_list_only) {
6451 assert(!r->is_young(), "we should not come across young regions");
6452
6453 if (r->isHumongous()) {
6454 // We ignore humongous regions, we left the humongous set unchanged
6455 } else {
6456 // The rest should be old, add them to the old set
6457 _old_set->add(r);
6458 }
6459 _total_used += r->used();
6460 }
6461
6462 return false;
6463 }
6464
6465 size_t total_used() {
6466 return _total_used;
6467 }
6468 };
6469
6470 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6471 assert_at_safepoint(true /* should_be_vm_thread */);
6472
6473 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6474 heap_region_iterate(&cl);
6475
6476 if (!free_list_only) {
6477 _summary_bytes_used = cl.total_used();
6478 }
6479 assert(_summary_bytes_used == recalculate_used(),
6480 err_msg("inconsistent _summary_bytes_used, "
6481 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6482 _summary_bytes_used, recalculate_used()));
6483 }
6484
6485 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6486 _refine_cte_cl->set_concurrent(concurrent);
6487 }
6488
6489 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6490 HeapRegion* hr = heap_region_containing(p);
6491 if (hr == NULL) {
6492 return false;
6493 } else {
6494 return hr->is_in(p);
6495 }
6496 }
6497
6498 // Methods for the mutator alloc region
6499
6500 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6501 bool force) {
6502 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6503 assert(!force || g1_policy()->can_expand_young_list(),
6504 "if force is true we should be able to expand the young list");
6505 bool young_list_full = g1_policy()->is_young_list_full();
6506 if (force || !young_list_full) {
6507 HeapRegion* new_alloc_region = new_region(word_size,
6508 false /* do_expand */);
6509 if (new_alloc_region != NULL) {
6510 set_region_short_lived_locked(new_alloc_region);
6511 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6512 return new_alloc_region;
6513 }
6514 }
6515 return NULL;
6516 }
6517
6518 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6519 size_t allocated_bytes) {
6520 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6521 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6522
6523 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6524 _summary_bytes_used += allocated_bytes;
6525 _hr_printer.retire(alloc_region);
6526 // We update the eden sizes here, when the region is retired,
6527 // instead of when it's allocated, since this is the point that its
6528 // used space has been recored in _summary_bytes_used.
6529 g1mm()->update_eden_size();
6530 }
6531
6532 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6533 bool force) {
6534 return _g1h->new_mutator_alloc_region(word_size, force);
6535 }
6536
6537 void G1CollectedHeap::set_par_threads() {
6538 // Don't change the number of workers. Use the value previously set
6539 // in the workgroup.
6540 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6541 uint n_workers = workers()->active_workers();
6542 assert(UseDynamicNumberOfGCThreads ||
6543 n_workers == workers()->total_workers(),
6544 "Otherwise should be using the total number of workers");
6545 if (n_workers == 0) {
6546 assert(false, "Should have been set in prior evacuation pause.");
6547 n_workers = ParallelGCThreads;
6548 workers()->set_active_workers(n_workers);
6549 }
6550 set_par_threads(n_workers);
6551 }
6552
6553 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6554 size_t allocated_bytes) {
6555 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6556 }
6557
6558 // Methods for the GC alloc regions
6559
6560 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6561 uint count,
6562 GCAllocPurpose ap) {
6563 assert(FreeList_lock->owned_by_self(), "pre-condition");
6564
6565 if (count < g1_policy()->max_regions(ap)) {
6566 HeapRegion* new_alloc_region = new_region(word_size,
6567 true /* do_expand */);
6568 if (new_alloc_region != NULL) {
6569 // We really only need to do this for old regions given that we
6570 // should never scan survivors. But it doesn't hurt to do it
6571 // for survivors too.
6572 new_alloc_region->set_saved_mark();
6573 if (ap == GCAllocForSurvived) {
6574 new_alloc_region->set_survivor();
6575 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6576 } else {
6577 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6578 }
6579 bool during_im = g1_policy()->during_initial_mark_pause();
6580 new_alloc_region->note_start_of_copying(during_im);
6581 return new_alloc_region;
6582 } else {
6583 g1_policy()->note_alloc_region_limit_reached(ap);
6584 }
6585 }
6586 return NULL;
6587 }
6588
6589 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6590 size_t allocated_bytes,
6591 GCAllocPurpose ap) {
6592 bool during_im = g1_policy()->during_initial_mark_pause();
6593 alloc_region->note_end_of_copying(during_im);
6594 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6595 if (ap == GCAllocForSurvived) {
6596 young_list()->add_survivor_region(alloc_region);
6597 } else {
6598 _old_set.add(alloc_region);
6599 }
6600 _hr_printer.retire(alloc_region);
6601 }
6602
6603 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6604 bool force) {
6605 assert(!force, "not supported for GC alloc regions");
6606 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6607 }
6608
6609 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6610 size_t allocated_bytes) {
6611 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6612 GCAllocForSurvived);
6613 }
6614
6615 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6616 bool force) {
6617 assert(!force, "not supported for GC alloc regions");
6618 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6619 }
6620
6621 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6622 size_t allocated_bytes) {
6623 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6624 GCAllocForTenured);
6625 }
6626 // Heap region set verification
6627
6628 class VerifyRegionListsClosure : public HeapRegionClosure {
6629 private:
6630 FreeRegionList* _free_list;
6631 OldRegionSet* _old_set;
6632 HumongousRegionSet* _humongous_set;
6633 uint _region_count;
6634
6635 public:
6636 VerifyRegionListsClosure(OldRegionSet* old_set,
6637 HumongousRegionSet* humongous_set,
6638 FreeRegionList* free_list) :
6639 _old_set(old_set), _humongous_set(humongous_set),
6640 _free_list(free_list), _region_count(0) { }
6641
6642 uint region_count() { return _region_count; }
6643
6644 bool doHeapRegion(HeapRegion* hr) {
6645 _region_count += 1;
6646
6647 if (hr->continuesHumongous()) {
6648 return false;
6649 }
6650
6651 if (hr->is_young()) {
6652 // TODO
6653 } else if (hr->startsHumongous()) {
6654 _humongous_set->verify_next_region(hr);
6655 } else if (hr->is_empty()) {
6656 _free_list->verify_next_region(hr);
6657 } else {
6658 _old_set->verify_next_region(hr);
6659 }
6660 return false;
6661 }
6662 };
6663
6664 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6665 HeapWord* bottom) {
6666 HeapWord* end = bottom + HeapRegion::GrainWords;
6667 MemRegion mr(bottom, end);
6668 assert(_g1_reserved.contains(mr), "invariant");
6669 // This might return NULL if the allocation fails
6670 return new HeapRegion(hrs_index, _bot_shared, mr);
6671 }
6672
6673 void G1CollectedHeap::verify_region_sets() {
6674 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6675
6676 // First, check the explicit lists.
6677 _free_list.verify();
6678 {
6679 // Given that a concurrent operation might be adding regions to
6680 // the secondary free list we have to take the lock before
6681 // verifying it.
6682 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6683 _secondary_free_list.verify();
6684 }
6685 _old_set.verify();
6686 _humongous_set.verify();
6687
6688 // If a concurrent region freeing operation is in progress it will
6689 // be difficult to correctly attributed any free regions we come
6690 // across to the correct free list given that they might belong to
6691 // one of several (free_list, secondary_free_list, any local lists,
6692 // etc.). So, if that's the case we will skip the rest of the
6693 // verification operation. Alternatively, waiting for the concurrent
6694 // operation to complete will have a non-trivial effect on the GC's
6695 // operation (no concurrent operation will last longer than the
6696 // interval between two calls to verification) and it might hide
6697 // any issues that we would like to catch during testing.
6698 if (free_regions_coming()) {
6699 return;
6700 }
6701
6702 // Make sure we append the secondary_free_list on the free_list so
6703 // that all free regions we will come across can be safely
6704 // attributed to the free_list.
6705 append_secondary_free_list_if_not_empty_with_lock();
6706
6707 // Finally, make sure that the region accounting in the lists is
6708 // consistent with what we see in the heap.
6709 _old_set.verify_start();
6710 _humongous_set.verify_start();
6711 _free_list.verify_start();
6712
6713 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6714 heap_region_iterate(&cl);
6715
6716 _old_set.verify_end();
6717 _humongous_set.verify_end();
6718 _free_list.verify_end();
6719 }
6720
6721 // Optimized nmethod scanning
6722
6723 class RegisterNMethodOopClosure: public OopClosure {
6724 G1CollectedHeap* _g1h;
6725 nmethod* _nm;
6726
6727 template <class T> void do_oop_work(T* p) {
6728 T heap_oop = oopDesc::load_heap_oop(p);
6729 if (!oopDesc::is_null(heap_oop)) {
6730 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6731 HeapRegion* hr = _g1h->heap_region_containing(obj);
6732 assert(!hr->continuesHumongous(),
6733 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6734 " starting at "HR_FORMAT,
6735 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6736
6737 // HeapRegion::add_strong_code_root() avoids adding duplicate
6738 // entries but having duplicates is OK since we "mark" nmethods
6739 // as visited when we scan the strong code root lists during the GC.
6740 hr->add_strong_code_root(_nm);
6741 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6742 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6743 _nm, HR_FORMAT_PARAMS(hr)));
6744 }
6745 }
6746
6747 public:
6748 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6749 _g1h(g1h), _nm(nm) {}
6750
6751 void do_oop(oop* p) { do_oop_work(p); }
6752 void do_oop(narrowOop* p) { do_oop_work(p); }
6753 };
6754
6755 class UnregisterNMethodOopClosure: public OopClosure {
6756 G1CollectedHeap* _g1h;
6757 nmethod* _nm;
6758
6759 template <class T> void do_oop_work(T* p) {
6760 T heap_oop = oopDesc::load_heap_oop(p);
6761 if (!oopDesc::is_null(heap_oop)) {
6762 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6763 HeapRegion* hr = _g1h->heap_region_containing(obj);
6764 assert(!hr->continuesHumongous(),
6765 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6766 " starting at "HR_FORMAT,
6767 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6768
6769 hr->remove_strong_code_root(_nm);
6770 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6771 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6772 _nm, HR_FORMAT_PARAMS(hr)));
6773 }
6774 }
6775
6776 public:
6777 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6778 _g1h(g1h), _nm(nm) {}
6779
6780 void do_oop(oop* p) { do_oop_work(p); }
6781 void do_oop(narrowOop* p) { do_oop_work(p); }
6782 };
6783
6784 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6785 CollectedHeap::register_nmethod(nm);
6786
6787 guarantee(nm != NULL, "sanity");
6788 RegisterNMethodOopClosure reg_cl(this, nm);
6789 nm->oops_do(®_cl);
6790 }
6791
6792 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6793 CollectedHeap::unregister_nmethod(nm);
6794
6795 guarantee(nm != NULL, "sanity");
6796 UnregisterNMethodOopClosure reg_cl(this, nm);
6797 nm->oops_do(®_cl, true);
6798 }
6799
6800 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6801 public:
6802 bool doHeapRegion(HeapRegion *hr) {
6803 assert(!hr->isHumongous(),
6804 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6805 HR_FORMAT_PARAMS(hr)));
6806 hr->migrate_strong_code_roots();
6807 return false;
6808 }
6809 };
6810
6811 void G1CollectedHeap::migrate_strong_code_roots() {
6812 MigrateCodeRootsHeapRegionClosure cl;
6813 double migrate_start = os::elapsedTime();
6814 collection_set_iterate(&cl);
6815 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6816 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6817 }
6818
6819 // Mark all the code roots that point into regions *not* in the
6820 // collection set.
6821 //
6822 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6823 // walking the the code roots lists of regions not in the collection
6824 // set. Suppose we have an nmethod (M) that points to objects in two
6825 // separate regions - one in the collection set (R1) and one not (R2).
6826 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6827 // nmethod M when walking the code roots for R1. When we come to scan
6828 // the code roots for R2, we would see that M is already marked and it
6829 // would be skipped and the objects in R2 that are referenced from M
6830 // would not be evacuated.
6831
6832 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6833
6834 class MarkStrongCodeRootOopClosure: public OopClosure {
6835 ConcurrentMark* _cm;
6836 HeapRegion* _hr;
6837 uint _worker_id;
6838
6839 template <class T> void do_oop_work(T* p) {
6840 T heap_oop = oopDesc::load_heap_oop(p);
6841 if (!oopDesc::is_null(heap_oop)) {
6842 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6843 // Only mark objects in the region (which is assumed
6844 // to be not in the collection set).
6845 if (_hr->is_in(obj)) {
6846 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6847 }
6848 }
6849 }
6850
6851 public:
6852 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6853 _cm(cm), _hr(hr), _worker_id(worker_id) {
6854 assert(!_hr->in_collection_set(), "sanity");
6855 }
6856
6857 void do_oop(narrowOop* p) { do_oop_work(p); }
6858 void do_oop(oop* p) { do_oop_work(p); }
6859 };
6860
6861 MarkStrongCodeRootOopClosure _oop_cl;
6862
6863 public:
6864 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6865 _oop_cl(cm, hr, worker_id) {}
6866
6867 void do_code_blob(CodeBlob* cb) {
6868 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6869 if (nm != NULL) {
6870 nm->oops_do(&_oop_cl);
6871 }
6872 }
6873 };
6874
6875 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6876 G1CollectedHeap* _g1h;
6877 uint _worker_id;
6878
6879 public:
6880 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6881 _g1h(g1h), _worker_id(worker_id) {}
6882
6883 bool doHeapRegion(HeapRegion *hr) {
6884 HeapRegionRemSet* hrrs = hr->rem_set();
6885 if (hr->continuesHumongous()) {
6886 // Code roots should never be attached to a continuation of a humongous region
6887 assert(hrrs->strong_code_roots_list_length() == 0,
6888 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6889 " starting at "HR_FORMAT", but has "INT32_FORMAT,
6890 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6891 hrrs->strong_code_roots_list_length()));
6892 return false;
6893 }
6894
6895 if (hr->in_collection_set()) {
6896 // Don't mark code roots into regions in the collection set here.
6897 // They will be marked when we scan them.
6898 return false;
6899 }
6900
6901 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6902 hr->strong_code_roots_do(&cb_cl);
6903 return false;
6904 }
6905 };
6906
6907 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6908 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6909 if (G1CollectedHeap::use_parallel_gc_threads()) {
6910 heap_region_par_iterate_chunked(&cl,
6911 worker_id,
6912 workers()->active_workers(),
6913 HeapRegion::ParMarkRootClaimValue);
6914 } else {
6915 heap_region_iterate(&cl);
6916 }
6917 }
6918
6919 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6920 G1CollectedHeap* _g1h;
6921
6922 public:
6923 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6924 _g1h(g1h) {}
6925
6926 void do_code_blob(CodeBlob* cb) {
6927 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6928 if (nm == NULL) {
6929 return;
6930 }
6931
6932 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6933 _g1h->register_nmethod(nm);
6934 }
6935 }
6936 };
6937
6938 void G1CollectedHeap::rebuild_strong_code_roots() {
6939 RebuildStrongCodeRootClosure blob_cl(this);
6940 CodeCache::blobs_do(&blob_cl);
6941 }