1 /*
2 * Copyright (c) 2001, 2014, 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 verify_region_sets_optional();
1302
1303 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1304 collector_policy()->should_clear_all_soft_refs();
1305
1306 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1307
1308 {
1309 IsGCActiveMark x;
1310
1311 // Timing
1312 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1313 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1314 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1315
1316 {
1317 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1318 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1319 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1320
1321 double start = os::elapsedTime();
1322 g1_policy()->record_full_collection_start();
1323
1324 // Note: When we have a more flexible GC logging framework that
1325 // allows us to add optional attributes to a GC log record we
1326 // could consider timing and reporting how long we wait in the
1327 // following two methods.
1328 wait_while_free_regions_coming();
1329 // If we start the compaction before the CM threads finish
1330 // scanning the root regions we might trip them over as we'll
1331 // be moving objects / updating references. So let's wait until
1332 // they are done. By telling them to abort, they should complete
1333 // early.
1334 _cm->root_regions()->abort();
1335 _cm->root_regions()->wait_until_scan_finished();
1336 append_secondary_free_list_if_not_empty_with_lock();
1337
1338 gc_prologue(true);
1339 increment_total_collections(true /* full gc */);
1340 increment_old_marking_cycles_started();
1341
1342 assert(used() == recalculate_used(), "Should be equal");
1343
1344 verify_before_gc();
1345
1346 pre_full_gc_dump(gc_timer);
1347
1348 COMPILER2_PRESENT(DerivedPointerTable::clear());
1349
1350 // Disable discovery and empty the discovered lists
1351 // for the CM ref processor.
1352 ref_processor_cm()->disable_discovery();
1353 ref_processor_cm()->abandon_partial_discovery();
1354 ref_processor_cm()->verify_no_references_recorded();
1355
1356 // Abandon current iterations of concurrent marking and concurrent
1357 // refinement, if any are in progress. We have to do this before
1358 // wait_until_scan_finished() below.
1359 concurrent_mark()->abort();
1360
1361 // Make sure we'll choose a new allocation region afterwards.
1362 release_mutator_alloc_region();
1363 abandon_gc_alloc_regions();
1364 g1_rem_set()->cleanupHRRS();
1365
1366 // We should call this after we retire any currently active alloc
1367 // regions so that all the ALLOC / RETIRE events are generated
1368 // before the start GC event.
1369 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1370
1371 // We may have added regions to the current incremental collection
1372 // set between the last GC or pause and now. We need to clear the
1373 // incremental collection set and then start rebuilding it afresh
1374 // after this full GC.
1375 abandon_collection_set(g1_policy()->inc_cset_head());
1376 g1_policy()->clear_incremental_cset();
1377 g1_policy()->stop_incremental_cset_building();
1378
1379 tear_down_region_sets(false /* free_list_only */);
1380 g1_policy()->set_gcs_are_young(true);
1381
1382 // See the comments in g1CollectedHeap.hpp and
1383 // G1CollectedHeap::ref_processing_init() about
1384 // how reference processing currently works in G1.
1385
1386 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1387 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1388
1389 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1390 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1391
1392 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1393 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1394
1395 // Do collection work
1396 {
1397 HandleMark hm; // Discard invalid handles created during gc
1398 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1399 }
1400
1401 assert(free_regions() == 0, "we should not have added any free regions");
1402 rebuild_region_sets(false /* free_list_only */);
1403
1404 // Enqueue any discovered reference objects that have
1405 // not been removed from the discovered lists.
1406 ref_processor_stw()->enqueue_discovered_references();
1407
1408 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1409
1410 MemoryService::track_memory_usage();
1411
1412 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1413 ref_processor_stw()->verify_no_references_recorded();
1414
1415 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1416 ClassLoaderDataGraph::purge();
1417 MetaspaceAux::verify_metrics();
1418
1419 // Note: since we've just done a full GC, concurrent
1420 // marking is no longer active. Therefore we need not
1421 // re-enable reference discovery for the CM ref processor.
1422 // That will be done at the start of the next marking cycle.
1423 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1424 ref_processor_cm()->verify_no_references_recorded();
1425
1426 reset_gc_time_stamp();
1427 // Since everything potentially moved, we will clear all remembered
1428 // sets, and clear all cards. Later we will rebuild remembered
1429 // sets. We will also reset the GC time stamps of the regions.
1430 clear_rsets_post_compaction();
1431 check_gc_time_stamps();
1432
1433 // Resize the heap if necessary.
1434 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1435
1436 if (_hr_printer.is_active()) {
1437 // We should do this after we potentially resize the heap so
1438 // that all the COMMIT / UNCOMMIT events are generated before
1439 // the end GC event.
1440
1441 print_hrs_post_compaction();
1442 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1443 }
1444
1445 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1446 if (hot_card_cache->use_cache()) {
1447 hot_card_cache->reset_card_counts();
1448 hot_card_cache->reset_hot_cache();
1449 }
1450
1451 // Rebuild remembered sets of all regions.
1452 if (G1CollectedHeap::use_parallel_gc_threads()) {
1453 uint n_workers =
1454 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1455 workers()->active_workers(),
1456 Threads::number_of_non_daemon_threads());
1457 assert(UseDynamicNumberOfGCThreads ||
1458 n_workers == workers()->total_workers(),
1459 "If not dynamic should be using all the workers");
1460 workers()->set_active_workers(n_workers);
1461 // Set parallel threads in the heap (_n_par_threads) only
1462 // before a parallel phase and always reset it to 0 after
1463 // the phase so that the number of parallel threads does
1464 // no get carried forward to a serial phase where there
1465 // may be code that is "possibly_parallel".
1466 set_par_threads(n_workers);
1467
1468 ParRebuildRSTask rebuild_rs_task(this);
1469 assert(check_heap_region_claim_values(
1470 HeapRegion::InitialClaimValue), "sanity check");
1471 assert(UseDynamicNumberOfGCThreads ||
1472 workers()->active_workers() == workers()->total_workers(),
1473 "Unless dynamic should use total workers");
1474 // Use the most recent number of active workers
1475 assert(workers()->active_workers() > 0,
1476 "Active workers not properly set");
1477 set_par_threads(workers()->active_workers());
1478 workers()->run_task(&rebuild_rs_task);
1479 set_par_threads(0);
1480 assert(check_heap_region_claim_values(
1481 HeapRegion::RebuildRSClaimValue), "sanity check");
1482 reset_heap_region_claim_values();
1483 } else {
1484 RebuildRSOutOfRegionClosure rebuild_rs(this);
1485 heap_region_iterate(&rebuild_rs);
1486 }
1487
1488 // Rebuild the strong code root lists for each region
1489 rebuild_strong_code_roots();
1490
1491 if (true) { // FIXME
1492 MetaspaceGC::compute_new_size();
1493 }
1494
1495 #ifdef TRACESPINNING
1496 ParallelTaskTerminator::print_termination_counts();
1497 #endif
1498
1499 // Discard all rset updates
1500 JavaThread::dirty_card_queue_set().abandon_logs();
1501 assert(!G1DeferredRSUpdate
1502 || (G1DeferredRSUpdate &&
1503 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1504
1505 _young_list->reset_sampled_info();
1506 // At this point there should be no regions in the
1507 // entire heap tagged as young.
1508 assert(check_young_list_empty(true /* check_heap */),
1509 "young list should be empty at this point");
1510
1511 // Update the number of full collections that have been completed.
1512 increment_old_marking_cycles_completed(false /* concurrent */);
1513
1514 _hrs.verify_optional();
1515 verify_region_sets_optional();
1516
1517 verify_after_gc();
1518
1519 // Start a new incremental collection set for the next pause
1520 assert(g1_policy()->collection_set() == NULL, "must be");
1521 g1_policy()->start_incremental_cset_building();
1522
1523 // Clear the _cset_fast_test bitmap in anticipation of adding
1524 // regions to the incremental collection set for the next
1525 // evacuation pause.
1526 clear_cset_fast_test();
1527
1528 init_mutator_alloc_region();
1529
1530 double end = os::elapsedTime();
1531 g1_policy()->record_full_collection_end();
1532
1533 if (G1Log::fine()) {
1534 g1_policy()->print_heap_transition();
1535 }
1536
1537 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1538 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1539 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1540 // before any GC notifications are raised.
1541 g1mm()->update_sizes();
1542
1543 gc_epilogue(true);
1544 }
1545
1546 if (G1Log::finer()) {
1547 g1_policy()->print_detailed_heap_transition(true /* full */);
1548 }
1549
1550 print_heap_after_gc();
1551 trace_heap_after_gc(gc_tracer);
1552
1553 post_full_gc_dump(gc_timer);
1554
1555 gc_timer->register_gc_end();
1556 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1557 }
1558
1559 return true;
1560 }
1561
1562 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1563 // do_collection() will return whether it succeeded in performing
1564 // the GC. Currently, there is no facility on the
1565 // do_full_collection() API to notify the caller than the collection
1566 // did not succeed (e.g., because it was locked out by the GC
1567 // locker). So, right now, we'll ignore the return value.
1568 bool dummy = do_collection(true, /* explicit_gc */
1569 clear_all_soft_refs,
1570 0 /* word_size */);
1571 }
1572
1573 // This code is mostly copied from TenuredGeneration.
1574 void
1575 G1CollectedHeap::
1576 resize_if_necessary_after_full_collection(size_t word_size) {
1577 // Include the current allocation, if any, and bytes that will be
1578 // pre-allocated to support collections, as "used".
1579 const size_t used_after_gc = used();
1580 const size_t capacity_after_gc = capacity();
1581 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1582
1583 // This is enforced in arguments.cpp.
1584 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1585 "otherwise the code below doesn't make sense");
1586
1587 // We don't have floating point command-line arguments
1588 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1589 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1590 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1591 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1592
1593 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1594 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1595
1596 // We have to be careful here as these two calculations can overflow
1597 // 32-bit size_t's.
1598 double used_after_gc_d = (double) used_after_gc;
1599 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1600 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1601
1602 // Let's make sure that they are both under the max heap size, which
1603 // by default will make them fit into a size_t.
1604 double desired_capacity_upper_bound = (double) max_heap_size;
1605 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1606 desired_capacity_upper_bound);
1607 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1608 desired_capacity_upper_bound);
1609
1610 // We can now safely turn them into size_t's.
1611 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1612 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1613
1614 // This assert only makes sense here, before we adjust them
1615 // with respect to the min and max heap size.
1616 assert(minimum_desired_capacity <= maximum_desired_capacity,
1617 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1618 "maximum_desired_capacity = "SIZE_FORMAT,
1619 minimum_desired_capacity, maximum_desired_capacity));
1620
1621 // Should not be greater than the heap max size. No need to adjust
1622 // it with respect to the heap min size as it's a lower bound (i.e.,
1623 // we'll try to make the capacity larger than it, not smaller).
1624 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1625 // Should not be less than the heap min size. No need to adjust it
1626 // with respect to the heap max size as it's an upper bound (i.e.,
1627 // we'll try to make the capacity smaller than it, not greater).
1628 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1629
1630 if (capacity_after_gc < minimum_desired_capacity) {
1631 // Don't expand unless it's significant
1632 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1633 ergo_verbose4(ErgoHeapSizing,
1634 "attempt heap expansion",
1635 ergo_format_reason("capacity lower than "
1636 "min desired capacity after Full GC")
1637 ergo_format_byte("capacity")
1638 ergo_format_byte("occupancy")
1639 ergo_format_byte_perc("min desired capacity"),
1640 capacity_after_gc, used_after_gc,
1641 minimum_desired_capacity, (double) MinHeapFreeRatio);
1642 expand(expand_bytes);
1643
1644 // No expansion, now see if we want to shrink
1645 } else if (capacity_after_gc > maximum_desired_capacity) {
1646 // Capacity too large, compute shrinking size
1647 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1648 ergo_verbose4(ErgoHeapSizing,
1649 "attempt heap shrinking",
1650 ergo_format_reason("capacity higher than "
1651 "max desired capacity after Full GC")
1652 ergo_format_byte("capacity")
1653 ergo_format_byte("occupancy")
1654 ergo_format_byte_perc("max desired capacity"),
1655 capacity_after_gc, used_after_gc,
1656 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1657 shrink(shrink_bytes);
1658 }
1659 }
1660
1661
1662 HeapWord*
1663 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1664 bool* succeeded) {
1665 assert_at_safepoint(true /* should_be_vm_thread */);
1666
1667 *succeeded = true;
1668 // Let's attempt the allocation first.
1669 HeapWord* result =
1670 attempt_allocation_at_safepoint(word_size,
1671 false /* expect_null_mutator_alloc_region */);
1672 if (result != NULL) {
1673 assert(*succeeded, "sanity");
1674 return result;
1675 }
1676
1677 // In a G1 heap, we're supposed to keep allocation from failing by
1678 // incremental pauses. Therefore, at least for now, we'll favor
1679 // expansion over collection. (This might change in the future if we can
1680 // do something smarter than full collection to satisfy a failed alloc.)
1681 result = expand_and_allocate(word_size);
1682 if (result != NULL) {
1683 assert(*succeeded, "sanity");
1684 return result;
1685 }
1686
1687 // Expansion didn't work, we'll try to do a Full GC.
1688 bool gc_succeeded = do_collection(false, /* explicit_gc */
1689 false, /* clear_all_soft_refs */
1690 word_size);
1691 if (!gc_succeeded) {
1692 *succeeded = false;
1693 return NULL;
1694 }
1695
1696 // Retry the allocation
1697 result = attempt_allocation_at_safepoint(word_size,
1698 true /* expect_null_mutator_alloc_region */);
1699 if (result != NULL) {
1700 assert(*succeeded, "sanity");
1701 return result;
1702 }
1703
1704 // Then, try a Full GC that will collect all soft references.
1705 gc_succeeded = do_collection(false, /* explicit_gc */
1706 true, /* clear_all_soft_refs */
1707 word_size);
1708 if (!gc_succeeded) {
1709 *succeeded = false;
1710 return NULL;
1711 }
1712
1713 // Retry the allocation once more
1714 result = attempt_allocation_at_safepoint(word_size,
1715 true /* expect_null_mutator_alloc_region */);
1716 if (result != NULL) {
1717 assert(*succeeded, "sanity");
1718 return result;
1719 }
1720
1721 assert(!collector_policy()->should_clear_all_soft_refs(),
1722 "Flag should have been handled and cleared prior to this point");
1723
1724 // What else? We might try synchronous finalization later. If the total
1725 // space available is large enough for the allocation, then a more
1726 // complete compaction phase than we've tried so far might be
1727 // appropriate.
1728 assert(*succeeded, "sanity");
1729 return NULL;
1730 }
1731
1732 // Attempting to expand the heap sufficiently
1733 // to support an allocation of the given "word_size". If
1734 // successful, perform the allocation and return the address of the
1735 // allocated block, or else "NULL".
1736
1737 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1738 assert_at_safepoint(true /* should_be_vm_thread */);
1739
1740 verify_region_sets_optional();
1741
1742 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1743 ergo_verbose1(ErgoHeapSizing,
1744 "attempt heap expansion",
1745 ergo_format_reason("allocation request failed")
1746 ergo_format_byte("allocation request"),
1747 word_size * HeapWordSize);
1748 if (expand(expand_bytes)) {
1749 _hrs.verify_optional();
1750 verify_region_sets_optional();
1751 return attempt_allocation_at_safepoint(word_size,
1752 false /* expect_null_mutator_alloc_region */);
1753 }
1754 return NULL;
1755 }
1756
1757 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1758 HeapWord* new_end) {
1759 assert(old_end != new_end, "don't call this otherwise");
1760 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1761
1762 // Update the committed mem region.
1763 _g1_committed.set_end(new_end);
1764 // Tell the card table about the update.
1765 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1766 // Tell the BOT about the update.
1767 _bot_shared->resize(_g1_committed.word_size());
1768 // Tell the hot card cache about the update
1769 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1770 }
1771
1772 bool G1CollectedHeap::expand(size_t expand_bytes) {
1773 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1774 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1775 HeapRegion::GrainBytes);
1776 ergo_verbose2(ErgoHeapSizing,
1777 "expand the heap",
1778 ergo_format_byte("requested expansion amount")
1779 ergo_format_byte("attempted expansion amount"),
1780 expand_bytes, aligned_expand_bytes);
1781
1782 if (_g1_storage.uncommitted_size() == 0) {
1783 ergo_verbose0(ErgoHeapSizing,
1784 "did not expand the heap",
1785 ergo_format_reason("heap already fully expanded"));
1786 return false;
1787 }
1788
1789 // First commit the memory.
1790 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1791 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1792 if (successful) {
1793 // Then propagate this update to the necessary data structures.
1794 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1795 update_committed_space(old_end, new_end);
1796
1797 FreeRegionList expansion_list("Local Expansion List");
1798 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1799 assert(mr.start() == old_end, "post-condition");
1800 // mr might be a smaller region than what was requested if
1801 // expand_by() was unable to allocate the HeapRegion instances
1802 assert(mr.end() <= new_end, "post-condition");
1803
1804 size_t actual_expand_bytes = mr.byte_size();
1805 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1806 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1807 "post-condition");
1808 if (actual_expand_bytes < aligned_expand_bytes) {
1809 // We could not expand _hrs to the desired size. In this case we
1810 // need to shrink the committed space accordingly.
1811 assert(mr.end() < new_end, "invariant");
1812
1813 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1814 // First uncommit the memory.
1815 _g1_storage.shrink_by(diff_bytes);
1816 // Then propagate this update to the necessary data structures.
1817 update_committed_space(new_end, mr.end());
1818 }
1819 _free_list.add_as_tail(&expansion_list);
1820
1821 if (_hr_printer.is_active()) {
1822 HeapWord* curr = mr.start();
1823 while (curr < mr.end()) {
1824 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1825 _hr_printer.commit(curr, curr_end);
1826 curr = curr_end;
1827 }
1828 assert(curr == mr.end(), "post-condition");
1829 }
1830 g1_policy()->record_new_heap_size(n_regions());
1831 } else {
1832 ergo_verbose0(ErgoHeapSizing,
1833 "did not expand the heap",
1834 ergo_format_reason("heap expansion operation failed"));
1835 // The expansion of the virtual storage space was unsuccessful.
1836 // Let's see if it was because we ran out of swap.
1837 if (G1ExitOnExpansionFailure &&
1838 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1839 // We had head room...
1840 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1841 }
1842 }
1843 return successful;
1844 }
1845
1846 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1847 size_t aligned_shrink_bytes =
1848 ReservedSpace::page_align_size_down(shrink_bytes);
1849 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1850 HeapRegion::GrainBytes);
1851 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1852
1853 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1854 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1855 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1856
1857 ergo_verbose3(ErgoHeapSizing,
1858 "shrink the heap",
1859 ergo_format_byte("requested shrinking amount")
1860 ergo_format_byte("aligned shrinking amount")
1861 ergo_format_byte("attempted shrinking amount"),
1862 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1863 if (num_regions_removed > 0) {
1864 _g1_storage.shrink_by(shrunk_bytes);
1865 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1866
1867 if (_hr_printer.is_active()) {
1868 HeapWord* curr = old_end;
1869 while (curr > new_end) {
1870 HeapWord* curr_end = curr;
1871 curr -= HeapRegion::GrainWords;
1872 _hr_printer.uncommit(curr, curr_end);
1873 }
1874 }
1875
1876 _expansion_regions += num_regions_removed;
1877 update_committed_space(old_end, new_end);
1878 HeapRegionRemSet::shrink_heap(n_regions());
1879 g1_policy()->record_new_heap_size(n_regions());
1880 } else {
1881 ergo_verbose0(ErgoHeapSizing,
1882 "did not shrink the heap",
1883 ergo_format_reason("heap shrinking operation failed"));
1884 }
1885 }
1886
1887 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1888 verify_region_sets_optional();
1889
1890 // We should only reach here at the end of a Full GC which means we
1891 // should not not be holding to any GC alloc regions. The method
1892 // below will make sure of that and do any remaining clean up.
1893 abandon_gc_alloc_regions();
1894
1895 // Instead of tearing down / rebuilding the free lists here, we
1896 // could instead use the remove_all_pending() method on free_list to
1897 // remove only the ones that we need to remove.
1898 tear_down_region_sets(true /* free_list_only */);
1899 shrink_helper(shrink_bytes);
1900 rebuild_region_sets(true /* free_list_only */);
1901
1902 _hrs.verify_optional();
1903 verify_region_sets_optional();
1904 }
1905
1906 // Public methods.
1907
1908 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1909 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1910 #endif // _MSC_VER
1911
1912
1913 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1914 SharedHeap(policy_),
1915 _g1_policy(policy_),
1916 _dirty_card_queue_set(false),
1917 _into_cset_dirty_card_queue_set(false),
1918 _is_alive_closure_cm(this),
1919 _is_alive_closure_stw(this),
1920 _ref_processor_cm(NULL),
1921 _ref_processor_stw(NULL),
1922 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1923 _bot_shared(NULL),
1924 _evac_failure_scan_stack(NULL),
1925 _mark_in_progress(false),
1926 _cg1r(NULL), _summary_bytes_used(0),
1927 _g1mm(NULL),
1928 _refine_cte_cl(NULL),
1929 _full_collection(false),
1930 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1931 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1932 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1933 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1934 _free_regions_coming(false),
1935 _young_list(new YoungList(this)),
1936 _gc_time_stamp(0),
1937 _retained_old_gc_alloc_region(NULL),
1938 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1939 _old_plab_stats(OldPLABSize, PLABWeight),
1940 _expand_heap_after_alloc_failure(true),
1941 _surviving_young_words(NULL),
1942 _old_marking_cycles_started(0),
1943 _old_marking_cycles_completed(0),
1944 _concurrent_cycle_started(false),
1945 _in_cset_fast_test(NULL),
1946 _in_cset_fast_test_base(NULL),
1947 _dirty_cards_region_list(NULL),
1948 _worker_cset_start_region(NULL),
1949 _worker_cset_start_region_time_stamp(NULL),
1950 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1951 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1952 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1953 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1954
1955 _g1h = this;
1956 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1957 vm_exit_during_initialization("Failed necessary allocation.");
1958 }
1959
1960 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1961
1962 int n_queues = MAX2((int)ParallelGCThreads, 1);
1963 _task_queues = new RefToScanQueueSet(n_queues);
1964
1965 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1966 assert(n_rem_sets > 0, "Invariant.");
1967
1968 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1969 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1970 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1971
1972 for (int i = 0; i < n_queues; i++) {
1973 RefToScanQueue* q = new RefToScanQueue();
1974 q->initialize();
1975 _task_queues->register_queue(i, q);
1976 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1977 }
1978 clear_cset_start_regions();
1979
1980 // Initialize the G1EvacuationFailureALot counters and flags.
1981 NOT_PRODUCT(reset_evacuation_should_fail();)
1982
1983 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1984 }
1985
1986 jint G1CollectedHeap::initialize() {
1987 CollectedHeap::pre_initialize();
1988 os::enable_vtime();
1989
1990 G1Log::init();
1991
1992 // Necessary to satisfy locking discipline assertions.
1993
1994 MutexLocker x(Heap_lock);
1995
1996 // We have to initialize the printer before committing the heap, as
1997 // it will be used then.
1998 _hr_printer.set_active(G1PrintHeapRegions);
1999
2000 // While there are no constraints in the GC code that HeapWordSize
2001 // be any particular value, there are multiple other areas in the
2002 // system which believe this to be true (e.g. oop->object_size in some
2003 // cases incorrectly returns the size in wordSize units rather than
2004 // HeapWordSize).
2005 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2006
2007 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2008 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2009 size_t heap_alignment = collector_policy()->heap_alignment();
2010
2011 // Ensure that the sizes are properly aligned.
2012 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2013 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2014 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2015
2016 _cg1r = new ConcurrentG1Refine(this);
2017
2018 // Reserve the maximum.
2019
2020 // When compressed oops are enabled, the preferred heap base
2021 // is calculated by subtracting the requested size from the
2022 // 32Gb boundary and using the result as the base address for
2023 // heap reservation. If the requested size is not aligned to
2024 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2025 // into the ReservedHeapSpace constructor) then the actual
2026 // base of the reserved heap may end up differing from the
2027 // address that was requested (i.e. the preferred heap base).
2028 // If this happens then we could end up using a non-optimal
2029 // compressed oops mode.
2030
2031 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2032 heap_alignment);
2033
2034 // It is important to do this in a way such that concurrent readers can't
2035 // temporarily think something is in the heap. (I've actually seen this
2036 // happen in asserts: DLD.)
2037 _reserved.set_word_size(0);
2038 _reserved.set_start((HeapWord*)heap_rs.base());
2039 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2040
2041 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2042
2043 // Create the gen rem set (and barrier set) for the entire reserved region.
2044 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2045 set_barrier_set(rem_set()->bs());
2046 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2047 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2048 return JNI_ENOMEM;
2049 }
2050
2051 // Also create a G1 rem set.
2052 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2053
2054 // Carve out the G1 part of the heap.
2055
2056 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2057 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2058 g1_rs.size()/HeapWordSize);
2059
2060 _g1_storage.initialize(g1_rs, 0);
2061 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2062 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2063 (HeapWord*) _g1_reserved.end());
2064 assert(_hrs.max_length() == _expansion_regions,
2065 err_msg("max length: %u expansion regions: %u",
2066 _hrs.max_length(), _expansion_regions));
2067
2068 // Do later initialization work for concurrent refinement.
2069 _cg1r->init();
2070
2071 // 6843694 - ensure that the maximum region index can fit
2072 // in the remembered set structures.
2073 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2074 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2075
2076 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2077 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2078 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2079 "too many cards per region");
2080
2081 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2082
2083 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2084 heap_word_size(init_byte_size));
2085
2086 _g1h = this;
2087
2088 _in_cset_fast_test_length = max_regions();
2089 _in_cset_fast_test_base =
2090 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2091
2092 // We're biasing _in_cset_fast_test to avoid subtracting the
2093 // beginning of the heap every time we want to index; basically
2094 // it's the same with what we do with the card table.
2095 _in_cset_fast_test = _in_cset_fast_test_base -
2096 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2097
2098 // Clear the _cset_fast_test bitmap in anticipation of adding
2099 // regions to the incremental collection set for the first
2100 // evacuation pause.
2101 clear_cset_fast_test();
2102
2103 // Create the ConcurrentMark data structure and thread.
2104 // (Must do this late, so that "max_regions" is defined.)
2105 _cm = new ConcurrentMark(this, heap_rs);
2106 if (_cm == NULL || !_cm->completed_initialization()) {
2107 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2108 return JNI_ENOMEM;
2109 }
2110 _cmThread = _cm->cmThread();
2111
2112 // Initialize the from_card cache structure of HeapRegionRemSet.
2113 HeapRegionRemSet::init_heap(max_regions());
2114
2115 // Now expand into the initial heap size.
2116 if (!expand(init_byte_size)) {
2117 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2118 return JNI_ENOMEM;
2119 }
2120
2121 // Perform any initialization actions delegated to the policy.
2122 g1_policy()->init();
2123
2124 _refine_cte_cl =
2125 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2126 g1_rem_set(),
2127 concurrent_g1_refine());
2128 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2129
2130 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2131 SATB_Q_FL_lock,
2132 G1SATBProcessCompletedThreshold,
2133 Shared_SATB_Q_lock);
2134
2135 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2136 DirtyCardQ_FL_lock,
2137 concurrent_g1_refine()->yellow_zone(),
2138 concurrent_g1_refine()->red_zone(),
2139 Shared_DirtyCardQ_lock);
2140
2141 if (G1DeferredRSUpdate) {
2142 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2143 DirtyCardQ_FL_lock,
2144 -1, // never trigger processing
2145 -1, // no limit on length
2146 Shared_DirtyCardQ_lock,
2147 &JavaThread::dirty_card_queue_set());
2148 }
2149
2150 // Initialize the card queue set used to hold cards containing
2151 // references into the collection set.
2152 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2153 DirtyCardQ_FL_lock,
2154 -1, // never trigger processing
2155 -1, // no limit on length
2156 Shared_DirtyCardQ_lock,
2157 &JavaThread::dirty_card_queue_set());
2158
2159 // In case we're keeping closure specialization stats, initialize those
2160 // counts and that mechanism.
2161 SpecializationStats::clear();
2162
2163 // Here we allocate the dummy full region that is required by the
2164 // G1AllocRegion class. If we don't pass an address in the reserved
2165 // space here, lots of asserts fire.
2166
2167 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2168 _g1_reserved.start());
2169 // We'll re-use the same region whether the alloc region will
2170 // require BOT updates or not and, if it doesn't, then a non-young
2171 // region will complain that it cannot support allocations without
2172 // BOT updates. So we'll tag the dummy region as young to avoid that.
2173 dummy_region->set_young();
2174 // Make sure it's full.
2175 dummy_region->set_top(dummy_region->end());
2176 G1AllocRegion::setup(this, dummy_region);
2177
2178 init_mutator_alloc_region();
2179
2180 // Do create of the monitoring and management support so that
2181 // values in the heap have been properly initialized.
2182 _g1mm = new G1MonitoringSupport(this);
2183
2184 return JNI_OK;
2185 }
2186
2187 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2188 return HeapRegion::max_region_size();
2189 }
2190
2191 void G1CollectedHeap::ref_processing_init() {
2192 // Reference processing in G1 currently works as follows:
2193 //
2194 // * There are two reference processor instances. One is
2195 // used to record and process discovered references
2196 // during concurrent marking; the other is used to
2197 // record and process references during STW pauses
2198 // (both full and incremental).
2199 // * Both ref processors need to 'span' the entire heap as
2200 // the regions in the collection set may be dotted around.
2201 //
2202 // * For the concurrent marking ref processor:
2203 // * Reference discovery is enabled at initial marking.
2204 // * Reference discovery is disabled and the discovered
2205 // references processed etc during remarking.
2206 // * Reference discovery is MT (see below).
2207 // * Reference discovery requires a barrier (see below).
2208 // * Reference processing may or may not be MT
2209 // (depending on the value of ParallelRefProcEnabled
2210 // and ParallelGCThreads).
2211 // * A full GC disables reference discovery by the CM
2212 // ref processor and abandons any entries on it's
2213 // discovered lists.
2214 //
2215 // * For the STW processor:
2216 // * Non MT discovery is enabled at the start of a full GC.
2217 // * Processing and enqueueing during a full GC is non-MT.
2218 // * During a full GC, references are processed after marking.
2219 //
2220 // * Discovery (may or may not be MT) is enabled at the start
2221 // of an incremental evacuation pause.
2222 // * References are processed near the end of a STW evacuation pause.
2223 // * For both types of GC:
2224 // * Discovery is atomic - i.e. not concurrent.
2225 // * Reference discovery will not need a barrier.
2226
2227 SharedHeap::ref_processing_init();
2228 MemRegion mr = reserved_region();
2229
2230 // Concurrent Mark ref processor
2231 _ref_processor_cm =
2232 new ReferenceProcessor(mr, // span
2233 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2234 // mt processing
2235 (int) ParallelGCThreads,
2236 // degree of mt processing
2237 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2238 // mt discovery
2239 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2240 // degree of mt discovery
2241 false,
2242 // Reference discovery is not atomic
2243 &_is_alive_closure_cm,
2244 // is alive closure
2245 // (for efficiency/performance)
2246 true);
2247 // Setting next fields of discovered
2248 // lists requires a barrier.
2249
2250 // STW ref processor
2251 _ref_processor_stw =
2252 new ReferenceProcessor(mr, // span
2253 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2254 // mt processing
2255 MAX2((int)ParallelGCThreads, 1),
2256 // degree of mt processing
2257 (ParallelGCThreads > 1),
2258 // mt discovery
2259 MAX2((int)ParallelGCThreads, 1),
2260 // degree of mt discovery
2261 true,
2262 // Reference discovery is atomic
2263 &_is_alive_closure_stw,
2264 // is alive closure
2265 // (for efficiency/performance)
2266 false);
2267 // Setting next fields of discovered
2268 // lists does not require a barrier.
2269 }
2270
2271 size_t G1CollectedHeap::capacity() const {
2272 return _g1_committed.byte_size();
2273 }
2274
2275 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2276 assert(!hr->continuesHumongous(), "pre-condition");
2277 hr->reset_gc_time_stamp();
2278 if (hr->startsHumongous()) {
2279 uint first_index = hr->hrs_index() + 1;
2280 uint last_index = hr->last_hc_index();
2281 for (uint i = first_index; i < last_index; i += 1) {
2282 HeapRegion* chr = region_at(i);
2283 assert(chr->continuesHumongous(), "sanity");
2284 chr->reset_gc_time_stamp();
2285 }
2286 }
2287 }
2288
2289 #ifndef PRODUCT
2290 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2291 private:
2292 unsigned _gc_time_stamp;
2293 bool _failures;
2294
2295 public:
2296 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2297 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2298
2299 virtual bool doHeapRegion(HeapRegion* hr) {
2300 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2301 if (_gc_time_stamp != region_gc_time_stamp) {
2302 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2303 "expected %d", HR_FORMAT_PARAMS(hr),
2304 region_gc_time_stamp, _gc_time_stamp);
2305 _failures = true;
2306 }
2307 return false;
2308 }
2309
2310 bool failures() { return _failures; }
2311 };
2312
2313 void G1CollectedHeap::check_gc_time_stamps() {
2314 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2315 heap_region_iterate(&cl);
2316 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2317 }
2318 #endif // PRODUCT
2319
2320 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2321 DirtyCardQueue* into_cset_dcq,
2322 bool concurrent,
2323 int worker_i) {
2324 // Clean cards in the hot card cache
2325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2326 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2327
2328 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2329 int n_completed_buffers = 0;
2330 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2331 n_completed_buffers++;
2332 }
2333 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2334 dcqs.clear_n_completed_buffers();
2335 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2336 }
2337
2338
2339 // Computes the sum of the storage used by the various regions.
2340
2341 size_t G1CollectedHeap::used() const {
2342 assert(Heap_lock->owner() != NULL,
2343 "Should be owned on this thread's behalf.");
2344 size_t result = _summary_bytes_used;
2345 // Read only once in case it is set to NULL concurrently
2346 HeapRegion* hr = _mutator_alloc_region.get();
2347 if (hr != NULL)
2348 result += hr->used();
2349 return result;
2350 }
2351
2352 size_t G1CollectedHeap::used_unlocked() const {
2353 size_t result = _summary_bytes_used;
2354 return result;
2355 }
2356
2357 class SumUsedClosure: public HeapRegionClosure {
2358 size_t _used;
2359 public:
2360 SumUsedClosure() : _used(0) {}
2361 bool doHeapRegion(HeapRegion* r) {
2362 if (!r->continuesHumongous()) {
2363 _used += r->used();
2364 }
2365 return false;
2366 }
2367 size_t result() { return _used; }
2368 };
2369
2370 size_t G1CollectedHeap::recalculate_used() const {
2371 SumUsedClosure blk;
2372 heap_region_iterate(&blk);
2373 return blk.result();
2374 }
2375
2376 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2377 switch (cause) {
2378 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2379 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2380 case GCCause::_g1_humongous_allocation: return true;
2381 default: return false;
2382 }
2383 }
2384
2385 #ifndef PRODUCT
2386 void G1CollectedHeap::allocate_dummy_regions() {
2387 // Let's fill up most of the region
2388 size_t word_size = HeapRegion::GrainWords - 1024;
2389 // And as a result the region we'll allocate will be humongous.
2390 guarantee(isHumongous(word_size), "sanity");
2391
2392 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2393 // Let's use the existing mechanism for the allocation
2394 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2395 if (dummy_obj != NULL) {
2396 MemRegion mr(dummy_obj, word_size);
2397 CollectedHeap::fill_with_object(mr);
2398 } else {
2399 // If we can't allocate once, we probably cannot allocate
2400 // again. Let's get out of the loop.
2401 break;
2402 }
2403 }
2404 }
2405 #endif // !PRODUCT
2406
2407 void G1CollectedHeap::increment_old_marking_cycles_started() {
2408 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2409 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2410 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2411 _old_marking_cycles_started, _old_marking_cycles_completed));
2412
2413 _old_marking_cycles_started++;
2414 }
2415
2416 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2417 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2418
2419 // We assume that if concurrent == true, then the caller is a
2420 // concurrent thread that was joined the Suspendible Thread
2421 // Set. If there's ever a cheap way to check this, we should add an
2422 // assert here.
2423
2424 // Given that this method is called at the end of a Full GC or of a
2425 // concurrent cycle, and those can be nested (i.e., a Full GC can
2426 // interrupt a concurrent cycle), the number of full collections
2427 // completed should be either one (in the case where there was no
2428 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2429 // behind the number of full collections started.
2430
2431 // This is the case for the inner caller, i.e. a Full GC.
2432 assert(concurrent ||
2433 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2434 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2435 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2436 "is inconsistent with _old_marking_cycles_completed = %u",
2437 _old_marking_cycles_started, _old_marking_cycles_completed));
2438
2439 // This is the case for the outer caller, i.e. the concurrent cycle.
2440 assert(!concurrent ||
2441 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2442 err_msg("for outer caller (concurrent cycle): "
2443 "_old_marking_cycles_started = %u "
2444 "is inconsistent with _old_marking_cycles_completed = %u",
2445 _old_marking_cycles_started, _old_marking_cycles_completed));
2446
2447 _old_marking_cycles_completed += 1;
2448
2449 // We need to clear the "in_progress" flag in the CM thread before
2450 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2451 // is set) so that if a waiter requests another System.gc() it doesn't
2452 // incorrectly see that a marking cycle is still in progress.
2453 if (concurrent) {
2454 _cmThread->clear_in_progress();
2455 }
2456
2457 // This notify_all() will ensure that a thread that called
2458 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2459 // and it's waiting for a full GC to finish will be woken up. It is
2460 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2461 FullGCCount_lock->notify_all();
2462 }
2463
2464 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2465 _concurrent_cycle_started = true;
2466 _gc_timer_cm->register_gc_start(start_time);
2467
2468 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2469 trace_heap_before_gc(_gc_tracer_cm);
2470 }
2471
2472 void G1CollectedHeap::register_concurrent_cycle_end() {
2473 if (_concurrent_cycle_started) {
2474 if (_cm->has_aborted()) {
2475 _gc_tracer_cm->report_concurrent_mode_failure();
2476 }
2477
2478 _gc_timer_cm->register_gc_end();
2479 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2480
2481 _concurrent_cycle_started = false;
2482 }
2483 }
2484
2485 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2486 if (_concurrent_cycle_started) {
2487 trace_heap_after_gc(_gc_tracer_cm);
2488 }
2489 }
2490
2491 G1YCType G1CollectedHeap::yc_type() {
2492 bool is_young = g1_policy()->gcs_are_young();
2493 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2494 bool is_during_mark = mark_in_progress();
2495
2496 if (is_initial_mark) {
2497 return InitialMark;
2498 } else if (is_during_mark) {
2499 return DuringMark;
2500 } else if (is_young) {
2501 return Normal;
2502 } else {
2503 return Mixed;
2504 }
2505 }
2506
2507 void G1CollectedHeap::collect(GCCause::Cause cause) {
2508 assert_heap_not_locked();
2509
2510 unsigned int gc_count_before;
2511 unsigned int old_marking_count_before;
2512 bool retry_gc;
2513
2514 do {
2515 retry_gc = false;
2516
2517 {
2518 MutexLocker ml(Heap_lock);
2519
2520 // Read the GC count while holding the Heap_lock
2521 gc_count_before = total_collections();
2522 old_marking_count_before = _old_marking_cycles_started;
2523 }
2524
2525 if (should_do_concurrent_full_gc(cause)) {
2526 // Schedule an initial-mark evacuation pause that will start a
2527 // concurrent cycle. We're setting word_size to 0 which means that
2528 // we are not requesting a post-GC allocation.
2529 VM_G1IncCollectionPause op(gc_count_before,
2530 0, /* word_size */
2531 true, /* should_initiate_conc_mark */
2532 g1_policy()->max_pause_time_ms(),
2533 cause);
2534
2535 VMThread::execute(&op);
2536 if (!op.pause_succeeded()) {
2537 if (old_marking_count_before == _old_marking_cycles_started) {
2538 retry_gc = op.should_retry_gc();
2539 } else {
2540 // A Full GC happened while we were trying to schedule the
2541 // initial-mark GC. No point in starting a new cycle given
2542 // that the whole heap was collected anyway.
2543 }
2544
2545 if (retry_gc) {
2546 if (GC_locker::is_active_and_needs_gc()) {
2547 GC_locker::stall_until_clear();
2548 }
2549 }
2550 }
2551 } else {
2552 if (cause == GCCause::_gc_locker
2553 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2554
2555 // Schedule a standard evacuation pause. We're setting word_size
2556 // to 0 which means that we are not requesting a post-GC allocation.
2557 VM_G1IncCollectionPause op(gc_count_before,
2558 0, /* word_size */
2559 false, /* should_initiate_conc_mark */
2560 g1_policy()->max_pause_time_ms(),
2561 cause);
2562 VMThread::execute(&op);
2563 } else {
2564 // Schedule a Full GC.
2565 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2566 VMThread::execute(&op);
2567 }
2568 }
2569 } while (retry_gc);
2570 }
2571
2572 bool G1CollectedHeap::is_in(const void* p) const {
2573 if (_g1_committed.contains(p)) {
2574 // Given that we know that p is in the committed space,
2575 // heap_region_containing_raw() should successfully
2576 // return the containing region.
2577 HeapRegion* hr = heap_region_containing_raw(p);
2578 return hr->is_in(p);
2579 } else {
2580 return false;
2581 }
2582 }
2583
2584 // Iteration functions.
2585
2586 // Iterates an OopClosure over all ref-containing fields of objects
2587 // within a HeapRegion.
2588
2589 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2590 MemRegion _mr;
2591 ExtendedOopClosure* _cl;
2592 public:
2593 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2594 : _mr(mr), _cl(cl) {}
2595 bool doHeapRegion(HeapRegion* r) {
2596 if (!r->continuesHumongous()) {
2597 r->oop_iterate(_cl);
2598 }
2599 return false;
2600 }
2601 };
2602
2603 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2604 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2605 heap_region_iterate(&blk);
2606 }
2607
2608 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2609 IterateOopClosureRegionClosure blk(mr, cl);
2610 heap_region_iterate(&blk);
2611 }
2612
2613 // Iterates an ObjectClosure over all objects within a HeapRegion.
2614
2615 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2616 ObjectClosure* _cl;
2617 public:
2618 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2619 bool doHeapRegion(HeapRegion* r) {
2620 if (! r->continuesHumongous()) {
2621 r->object_iterate(_cl);
2622 }
2623 return false;
2624 }
2625 };
2626
2627 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2628 IterateObjectClosureRegionClosure blk(cl);
2629 heap_region_iterate(&blk);
2630 }
2631
2632 // Calls a SpaceClosure on a HeapRegion.
2633
2634 class SpaceClosureRegionClosure: public HeapRegionClosure {
2635 SpaceClosure* _cl;
2636 public:
2637 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2638 bool doHeapRegion(HeapRegion* r) {
2639 _cl->do_space(r);
2640 return false;
2641 }
2642 };
2643
2644 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2645 SpaceClosureRegionClosure blk(cl);
2646 heap_region_iterate(&blk);
2647 }
2648
2649 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2650 _hrs.iterate(cl);
2651 }
2652
2653 void
2654 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2655 uint worker_id,
2656 uint no_of_par_workers,
2657 jint claim_value) {
2658 const uint regions = n_regions();
2659 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2660 no_of_par_workers :
2661 1);
2662 assert(UseDynamicNumberOfGCThreads ||
2663 no_of_par_workers == workers()->total_workers(),
2664 "Non dynamic should use fixed number of workers");
2665 // try to spread out the starting points of the workers
2666 const HeapRegion* start_hr =
2667 start_region_for_worker(worker_id, no_of_par_workers);
2668 const uint start_index = start_hr->hrs_index();
2669
2670 // each worker will actually look at all regions
2671 for (uint count = 0; count < regions; ++count) {
2672 const uint index = (start_index + count) % regions;
2673 assert(0 <= index && index < regions, "sanity");
2674 HeapRegion* r = region_at(index);
2675 // we'll ignore "continues humongous" regions (we'll process them
2676 // when we come across their corresponding "start humongous"
2677 // region) and regions already claimed
2678 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2679 continue;
2680 }
2681 // OK, try to claim it
2682 if (r->claimHeapRegion(claim_value)) {
2683 // success!
2684 assert(!r->continuesHumongous(), "sanity");
2685 if (r->startsHumongous()) {
2686 // If the region is "starts humongous" we'll iterate over its
2687 // "continues humongous" first; in fact we'll do them
2688 // first. The order is important. In on case, calling the
2689 // closure on the "starts humongous" region might de-allocate
2690 // and clear all its "continues humongous" regions and, as a
2691 // result, we might end up processing them twice. So, we'll do
2692 // them first (notice: most closures will ignore them anyway) and
2693 // then we'll do the "starts humongous" region.
2694 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2695 HeapRegion* chr = region_at(ch_index);
2696
2697 // if the region has already been claimed or it's not
2698 // "continues humongous" we're done
2699 if (chr->claim_value() == claim_value ||
2700 !chr->continuesHumongous()) {
2701 break;
2702 }
2703
2704 // No one should have claimed it directly. We can given
2705 // that we claimed its "starts humongous" region.
2706 assert(chr->claim_value() != claim_value, "sanity");
2707 assert(chr->humongous_start_region() == r, "sanity");
2708
2709 if (chr->claimHeapRegion(claim_value)) {
2710 // we should always be able to claim it; no one else should
2711 // be trying to claim this region
2712
2713 bool res2 = cl->doHeapRegion(chr);
2714 assert(!res2, "Should not abort");
2715
2716 // Right now, this holds (i.e., no closure that actually
2717 // does something with "continues humongous" regions
2718 // clears them). We might have to weaken it in the future,
2719 // but let's leave these two asserts here for extra safety.
2720 assert(chr->continuesHumongous(), "should still be the case");
2721 assert(chr->humongous_start_region() == r, "sanity");
2722 } else {
2723 guarantee(false, "we should not reach here");
2724 }
2725 }
2726 }
2727
2728 assert(!r->continuesHumongous(), "sanity");
2729 bool res = cl->doHeapRegion(r);
2730 assert(!res, "Should not abort");
2731 }
2732 }
2733 }
2734
2735 class ResetClaimValuesClosure: public HeapRegionClosure {
2736 public:
2737 bool doHeapRegion(HeapRegion* r) {
2738 r->set_claim_value(HeapRegion::InitialClaimValue);
2739 return false;
2740 }
2741 };
2742
2743 void G1CollectedHeap::reset_heap_region_claim_values() {
2744 ResetClaimValuesClosure blk;
2745 heap_region_iterate(&blk);
2746 }
2747
2748 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2749 ResetClaimValuesClosure blk;
2750 collection_set_iterate(&blk);
2751 }
2752
2753 #ifdef ASSERT
2754 // This checks whether all regions in the heap have the correct claim
2755 // value. I also piggy-backed on this a check to ensure that the
2756 // humongous_start_region() information on "continues humongous"
2757 // regions is correct.
2758
2759 class CheckClaimValuesClosure : public HeapRegionClosure {
2760 private:
2761 jint _claim_value;
2762 uint _failures;
2763 HeapRegion* _sh_region;
2764
2765 public:
2766 CheckClaimValuesClosure(jint claim_value) :
2767 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2768 bool doHeapRegion(HeapRegion* r) {
2769 if (r->claim_value() != _claim_value) {
2770 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2771 "claim value = %d, should be %d",
2772 HR_FORMAT_PARAMS(r),
2773 r->claim_value(), _claim_value);
2774 ++_failures;
2775 }
2776 if (!r->isHumongous()) {
2777 _sh_region = NULL;
2778 } else if (r->startsHumongous()) {
2779 _sh_region = r;
2780 } else if (r->continuesHumongous()) {
2781 if (r->humongous_start_region() != _sh_region) {
2782 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2783 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2784 HR_FORMAT_PARAMS(r),
2785 r->humongous_start_region(),
2786 _sh_region);
2787 ++_failures;
2788 }
2789 }
2790 return false;
2791 }
2792 uint failures() { return _failures; }
2793 };
2794
2795 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2796 CheckClaimValuesClosure cl(claim_value);
2797 heap_region_iterate(&cl);
2798 return cl.failures() == 0;
2799 }
2800
2801 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2802 private:
2803 jint _claim_value;
2804 uint _failures;
2805
2806 public:
2807 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2808 _claim_value(claim_value), _failures(0) { }
2809
2810 uint failures() { return _failures; }
2811
2812 bool doHeapRegion(HeapRegion* hr) {
2813 assert(hr->in_collection_set(), "how?");
2814 assert(!hr->isHumongous(), "H-region in CSet");
2815 if (hr->claim_value() != _claim_value) {
2816 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2817 "claim value = %d, should be %d",
2818 HR_FORMAT_PARAMS(hr),
2819 hr->claim_value(), _claim_value);
2820 _failures += 1;
2821 }
2822 return false;
2823 }
2824 };
2825
2826 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2827 CheckClaimValuesInCSetHRClosure cl(claim_value);
2828 collection_set_iterate(&cl);
2829 return cl.failures() == 0;
2830 }
2831 #endif // ASSERT
2832
2833 // Clear the cached CSet starting regions and (more importantly)
2834 // the time stamps. Called when we reset the GC time stamp.
2835 void G1CollectedHeap::clear_cset_start_regions() {
2836 assert(_worker_cset_start_region != NULL, "sanity");
2837 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2838
2839 int n_queues = MAX2((int)ParallelGCThreads, 1);
2840 for (int i = 0; i < n_queues; i++) {
2841 _worker_cset_start_region[i] = NULL;
2842 _worker_cset_start_region_time_stamp[i] = 0;
2843 }
2844 }
2845
2846 // Given the id of a worker, obtain or calculate a suitable
2847 // starting region for iterating over the current collection set.
2848 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2849 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2850
2851 HeapRegion* result = NULL;
2852 unsigned gc_time_stamp = get_gc_time_stamp();
2853
2854 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2855 // Cached starting region for current worker was set
2856 // during the current pause - so it's valid.
2857 // Note: the cached starting heap region may be NULL
2858 // (when the collection set is empty).
2859 result = _worker_cset_start_region[worker_i];
2860 assert(result == NULL || result->in_collection_set(), "sanity");
2861 return result;
2862 }
2863
2864 // The cached entry was not valid so let's calculate
2865 // a suitable starting heap region for this worker.
2866
2867 // We want the parallel threads to start their collection
2868 // set iteration at different collection set regions to
2869 // avoid contention.
2870 // If we have:
2871 // n collection set regions
2872 // p threads
2873 // Then thread t will start at region floor ((t * n) / p)
2874
2875 result = g1_policy()->collection_set();
2876 if (G1CollectedHeap::use_parallel_gc_threads()) {
2877 uint cs_size = g1_policy()->cset_region_length();
2878 uint active_workers = workers()->active_workers();
2879 assert(UseDynamicNumberOfGCThreads ||
2880 active_workers == workers()->total_workers(),
2881 "Unless dynamic should use total workers");
2882
2883 uint end_ind = (cs_size * worker_i) / active_workers;
2884 uint start_ind = 0;
2885
2886 if (worker_i > 0 &&
2887 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2888 // Previous workers starting region is valid
2889 // so let's iterate from there
2890 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2891 result = _worker_cset_start_region[worker_i - 1];
2892 }
2893
2894 for (uint i = start_ind; i < end_ind; i++) {
2895 result = result->next_in_collection_set();
2896 }
2897 }
2898
2899 // Note: the calculated starting heap region may be NULL
2900 // (when the collection set is empty).
2901 assert(result == NULL || result->in_collection_set(), "sanity");
2902 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2903 "should be updated only once per pause");
2904 _worker_cset_start_region[worker_i] = result;
2905 OrderAccess::storestore();
2906 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2907 return result;
2908 }
2909
2910 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2911 uint no_of_par_workers) {
2912 uint worker_num =
2913 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2914 assert(UseDynamicNumberOfGCThreads ||
2915 no_of_par_workers == workers()->total_workers(),
2916 "Non dynamic should use fixed number of workers");
2917 const uint start_index = n_regions() * worker_i / worker_num;
2918 return region_at(start_index);
2919 }
2920
2921 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2922 HeapRegion* r = g1_policy()->collection_set();
2923 while (r != NULL) {
2924 HeapRegion* next = r->next_in_collection_set();
2925 if (cl->doHeapRegion(r)) {
2926 cl->incomplete();
2927 return;
2928 }
2929 r = next;
2930 }
2931 }
2932
2933 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2934 HeapRegionClosure *cl) {
2935 if (r == NULL) {
2936 // The CSet is empty so there's nothing to do.
2937 return;
2938 }
2939
2940 assert(r->in_collection_set(),
2941 "Start region must be a member of the collection set.");
2942 HeapRegion* cur = r;
2943 while (cur != NULL) {
2944 HeapRegion* next = cur->next_in_collection_set();
2945 if (cl->doHeapRegion(cur) && false) {
2946 cl->incomplete();
2947 return;
2948 }
2949 cur = next;
2950 }
2951 cur = g1_policy()->collection_set();
2952 while (cur != r) {
2953 HeapRegion* next = cur->next_in_collection_set();
2954 if (cl->doHeapRegion(cur) && false) {
2955 cl->incomplete();
2956 return;
2957 }
2958 cur = next;
2959 }
2960 }
2961
2962 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2963 return n_regions() > 0 ? region_at(0) : NULL;
2964 }
2965
2966
2967 Space* G1CollectedHeap::space_containing(const void* addr) const {
2968 Space* res = heap_region_containing(addr);
2969 return res;
2970 }
2971
2972 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2973 Space* sp = space_containing(addr);
2974 if (sp != NULL) {
2975 return sp->block_start(addr);
2976 }
2977 return NULL;
2978 }
2979
2980 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2981 Space* sp = space_containing(addr);
2982 assert(sp != NULL, "block_size of address outside of heap");
2983 return sp->block_size(addr);
2984 }
2985
2986 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2987 Space* sp = space_containing(addr);
2988 return sp->block_is_obj(addr);
2989 }
2990
2991 bool G1CollectedHeap::supports_tlab_allocation() const {
2992 return true;
2993 }
2994
2995 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2996 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2997 }
2998
2999 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
3000 return young_list()->eden_used_bytes();
3001 }
3002
3003 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3004 // must be smaller than the humongous object limit.
3005 size_t G1CollectedHeap::max_tlab_size() const {
3006 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3007 }
3008
3009 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3010 // Return the remaining space in the cur alloc region, but not less than
3011 // the min TLAB size.
3012
3013 // Also, this value can be at most the humongous object threshold,
3014 // since we can't allow tlabs to grow big enough to accommodate
3015 // humongous objects.
3016
3017 HeapRegion* hr = _mutator_alloc_region.get();
3018 size_t max_tlab = max_tlab_size() * wordSize;
3019 if (hr == NULL) {
3020 return max_tlab;
3021 } else {
3022 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3023 }
3024 }
3025
3026 size_t G1CollectedHeap::max_capacity() const {
3027 return _g1_reserved.byte_size();
3028 }
3029
3030 jlong G1CollectedHeap::millis_since_last_gc() {
3031 // assert(false, "NYI");
3032 return 0;
3033 }
3034
3035 void G1CollectedHeap::prepare_for_verify() {
3036 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3037 ensure_parsability(false);
3038 }
3039 g1_rem_set()->prepare_for_verify();
3040 }
3041
3042 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3043 VerifyOption vo) {
3044 switch (vo) {
3045 case VerifyOption_G1UsePrevMarking:
3046 return hr->obj_allocated_since_prev_marking(obj);
3047 case VerifyOption_G1UseNextMarking:
3048 return hr->obj_allocated_since_next_marking(obj);
3049 case VerifyOption_G1UseMarkWord:
3050 return false;
3051 default:
3052 ShouldNotReachHere();
3053 }
3054 return false; // keep some compilers happy
3055 }
3056
3057 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3058 switch (vo) {
3059 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3060 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3061 case VerifyOption_G1UseMarkWord: return NULL;
3062 default: ShouldNotReachHere();
3063 }
3064 return NULL; // keep some compilers happy
3065 }
3066
3067 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3068 switch (vo) {
3069 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3070 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3071 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3072 default: ShouldNotReachHere();
3073 }
3074 return false; // keep some compilers happy
3075 }
3076
3077 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3078 switch (vo) {
3079 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3080 case VerifyOption_G1UseNextMarking: return "NTAMS";
3081 case VerifyOption_G1UseMarkWord: return "NONE";
3082 default: ShouldNotReachHere();
3083 }
3084 return NULL; // keep some compilers happy
3085 }
3086
3087 class VerifyRootsClosure: public OopClosure {
3088 private:
3089 G1CollectedHeap* _g1h;
3090 VerifyOption _vo;
3091 bool _failures;
3092 public:
3093 // _vo == UsePrevMarking -> use "prev" marking information,
3094 // _vo == UseNextMarking -> use "next" marking information,
3095 // _vo == UseMarkWord -> use mark word from object header.
3096 VerifyRootsClosure(VerifyOption vo) :
3097 _g1h(G1CollectedHeap::heap()),
3098 _vo(vo),
3099 _failures(false) { }
3100
3101 bool failures() { return _failures; }
3102
3103 template <class T> void do_oop_nv(T* p) {
3104 T heap_oop = oopDesc::load_heap_oop(p);
3105 if (!oopDesc::is_null(heap_oop)) {
3106 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3107 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3108 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3109 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3110 if (_vo == VerifyOption_G1UseMarkWord) {
3111 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3112 }
3113 obj->print_on(gclog_or_tty);
3114 _failures = true;
3115 }
3116 }
3117 }
3118
3119 void do_oop(oop* p) { do_oop_nv(p); }
3120 void do_oop(narrowOop* p) { do_oop_nv(p); }
3121 };
3122
3123 class G1VerifyCodeRootOopClosure: public OopClosure {
3124 G1CollectedHeap* _g1h;
3125 OopClosure* _root_cl;
3126 nmethod* _nm;
3127 VerifyOption _vo;
3128 bool _failures;
3129
3130 template <class T> void do_oop_work(T* p) {
3131 // First verify that this root is live
3132 _root_cl->do_oop(p);
3133
3134 if (!G1VerifyHeapRegionCodeRoots) {
3135 // We're not verifying the code roots attached to heap region.
3136 return;
3137 }
3138
3139 // Don't check the code roots during marking verification in a full GC
3140 if (_vo == VerifyOption_G1UseMarkWord) {
3141 return;
3142 }
3143
3144 // Now verify that the current nmethod (which contains p) is
3145 // in the code root list of the heap region containing the
3146 // object referenced by p.
3147
3148 T heap_oop = oopDesc::load_heap_oop(p);
3149 if (!oopDesc::is_null(heap_oop)) {
3150 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3151
3152 // Now fetch the region containing the object
3153 HeapRegion* hr = _g1h->heap_region_containing(obj);
3154 HeapRegionRemSet* hrrs = hr->rem_set();
3155 // Verify that the strong code root list for this region
3156 // contains the nmethod
3157 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3158 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3159 "from nmethod "PTR_FORMAT" not in strong "
3160 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3161 p, _nm, hr->bottom(), hr->end());
3162 _failures = true;
3163 }
3164 }
3165 }
3166
3167 public:
3168 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3169 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3170
3171 void do_oop(oop* p) { do_oop_work(p); }
3172 void do_oop(narrowOop* p) { do_oop_work(p); }
3173
3174 void set_nmethod(nmethod* nm) { _nm = nm; }
3175 bool failures() { return _failures; }
3176 };
3177
3178 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3179 G1VerifyCodeRootOopClosure* _oop_cl;
3180
3181 public:
3182 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3183 _oop_cl(oop_cl) {}
3184
3185 void do_code_blob(CodeBlob* cb) {
3186 nmethod* nm = cb->as_nmethod_or_null();
3187 if (nm != NULL) {
3188 _oop_cl->set_nmethod(nm);
3189 nm->oops_do(_oop_cl);
3190 }
3191 }
3192 };
3193
3194 class YoungRefCounterClosure : public OopClosure {
3195 G1CollectedHeap* _g1h;
3196 int _count;
3197 public:
3198 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3199 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3200 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3201
3202 int count() { return _count; }
3203 void reset_count() { _count = 0; };
3204 };
3205
3206 class VerifyKlassClosure: public KlassClosure {
3207 YoungRefCounterClosure _young_ref_counter_closure;
3208 OopClosure *_oop_closure;
3209 public:
3210 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3211 void do_klass(Klass* k) {
3212 k->oops_do(_oop_closure);
3213
3214 _young_ref_counter_closure.reset_count();
3215 k->oops_do(&_young_ref_counter_closure);
3216 if (_young_ref_counter_closure.count() > 0) {
3217 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3218 }
3219 }
3220 };
3221
3222 class VerifyLivenessOopClosure: public OopClosure {
3223 G1CollectedHeap* _g1h;
3224 VerifyOption _vo;
3225 public:
3226 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3227 _g1h(g1h), _vo(vo)
3228 { }
3229 void do_oop(narrowOop *p) { do_oop_work(p); }
3230 void do_oop( oop *p) { do_oop_work(p); }
3231
3232 template <class T> void do_oop_work(T *p) {
3233 oop obj = oopDesc::load_decode_heap_oop(p);
3234 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3235 "Dead object referenced by a not dead object");
3236 }
3237 };
3238
3239 class VerifyObjsInRegionClosure: public ObjectClosure {
3240 private:
3241 G1CollectedHeap* _g1h;
3242 size_t _live_bytes;
3243 HeapRegion *_hr;
3244 VerifyOption _vo;
3245 public:
3246 // _vo == UsePrevMarking -> use "prev" marking information,
3247 // _vo == UseNextMarking -> use "next" marking information,
3248 // _vo == UseMarkWord -> use mark word from object header.
3249 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3250 : _live_bytes(0), _hr(hr), _vo(vo) {
3251 _g1h = G1CollectedHeap::heap();
3252 }
3253 void do_object(oop o) {
3254 VerifyLivenessOopClosure isLive(_g1h, _vo);
3255 assert(o != NULL, "Huh?");
3256 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3257 // If the object is alive according to the mark word,
3258 // then verify that the marking information agrees.
3259 // Note we can't verify the contra-positive of the
3260 // above: if the object is dead (according to the mark
3261 // word), it may not be marked, or may have been marked
3262 // but has since became dead, or may have been allocated
3263 // since the last marking.
3264 if (_vo == VerifyOption_G1UseMarkWord) {
3265 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3266 }
3267
3268 o->oop_iterate_no_header(&isLive);
3269 if (!_hr->obj_allocated_since_prev_marking(o)) {
3270 size_t obj_size = o->size(); // Make sure we don't overflow
3271 _live_bytes += (obj_size * HeapWordSize);
3272 }
3273 }
3274 }
3275 size_t live_bytes() { return _live_bytes; }
3276 };
3277
3278 class PrintObjsInRegionClosure : public ObjectClosure {
3279 HeapRegion *_hr;
3280 G1CollectedHeap *_g1;
3281 public:
3282 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3283 _g1 = G1CollectedHeap::heap();
3284 };
3285
3286 void do_object(oop o) {
3287 if (o != NULL) {
3288 HeapWord *start = (HeapWord *) o;
3289 size_t word_sz = o->size();
3290 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3291 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3292 (void*) o, word_sz,
3293 _g1->isMarkedPrev(o),
3294 _g1->isMarkedNext(o),
3295 _hr->obj_allocated_since_prev_marking(o));
3296 HeapWord *end = start + word_sz;
3297 HeapWord *cur;
3298 int *val;
3299 for (cur = start; cur < end; cur++) {
3300 val = (int *) cur;
3301 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3302 }
3303 }
3304 }
3305 };
3306
3307 class VerifyRegionClosure: public HeapRegionClosure {
3308 private:
3309 bool _par;
3310 VerifyOption _vo;
3311 bool _failures;
3312 public:
3313 // _vo == UsePrevMarking -> use "prev" marking information,
3314 // _vo == UseNextMarking -> use "next" marking information,
3315 // _vo == UseMarkWord -> use mark word from object header.
3316 VerifyRegionClosure(bool par, VerifyOption vo)
3317 : _par(par),
3318 _vo(vo),
3319 _failures(false) {}
3320
3321 bool failures() {
3322 return _failures;
3323 }
3324
3325 bool doHeapRegion(HeapRegion* r) {
3326 if (!r->continuesHumongous()) {
3327 bool failures = false;
3328 r->verify(_vo, &failures);
3329 if (failures) {
3330 _failures = true;
3331 } else {
3332 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3333 r->object_iterate(¬_dead_yet_cl);
3334 if (_vo != VerifyOption_G1UseNextMarking) {
3335 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3336 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3337 "max_live_bytes "SIZE_FORMAT" "
3338 "< calculated "SIZE_FORMAT,
3339 r->bottom(), r->end(),
3340 r->max_live_bytes(),
3341 not_dead_yet_cl.live_bytes());
3342 _failures = true;
3343 }
3344 } else {
3345 // When vo == UseNextMarking we cannot currently do a sanity
3346 // check on the live bytes as the calculation has not been
3347 // finalized yet.
3348 }
3349 }
3350 }
3351 return false; // stop the region iteration if we hit a failure
3352 }
3353 };
3354
3355 // This is the task used for parallel verification of the heap regions
3356
3357 class G1ParVerifyTask: public AbstractGangTask {
3358 private:
3359 G1CollectedHeap* _g1h;
3360 VerifyOption _vo;
3361 bool _failures;
3362
3363 public:
3364 // _vo == UsePrevMarking -> use "prev" marking information,
3365 // _vo == UseNextMarking -> use "next" marking information,
3366 // _vo == UseMarkWord -> use mark word from object header.
3367 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3368 AbstractGangTask("Parallel verify task"),
3369 _g1h(g1h),
3370 _vo(vo),
3371 _failures(false) { }
3372
3373 bool failures() {
3374 return _failures;
3375 }
3376
3377 void work(uint worker_id) {
3378 HandleMark hm;
3379 VerifyRegionClosure blk(true, _vo);
3380 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3381 _g1h->workers()->active_workers(),
3382 HeapRegion::ParVerifyClaimValue);
3383 if (blk.failures()) {
3384 _failures = true;
3385 }
3386 }
3387 };
3388
3389 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3390 if (SafepointSynchronize::is_at_safepoint()) {
3391 assert(Thread::current()->is_VM_thread(),
3392 "Expected to be executed serially by the VM thread at this point");
3393
3394 if (!silent) { gclog_or_tty->print("Roots "); }
3395 VerifyRootsClosure rootsCl(vo);
3396 VerifyKlassClosure klassCl(this, &rootsCl);
3397
3398 // We apply the relevant closures to all the oops in the
3399 // system dictionary, class loader data graph and the string table.
3400 // Don't verify the code cache here, since it's verified below.
3401 const int so = SO_AllClasses | SO_Strings;
3402
3403 // Need cleared claim bits for the strong roots processing
3404 ClassLoaderDataGraph::clear_claimed_marks();
3405
3406 process_strong_roots(true, // activate StrongRootsScope
3407 ScanningOption(so), // roots scanning options
3408 &rootsCl,
3409 &klassCl
3410 );
3411
3412 // Verify the nmethods in the code cache.
3413 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3414 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3415 CodeCache::blobs_do(&blobsCl);
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 verify_region_sets_optional();
3890 verify_dirty_young_regions();
3891
3892 // This call will decide whether this pause is an initial-mark
3893 // pause. If it is, during_initial_mark_pause() will return true
3894 // for the duration of this pause.
3895 g1_policy()->decide_on_conc_mark_initiation();
3896
3897 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3898 assert(!g1_policy()->during_initial_mark_pause() ||
3899 g1_policy()->gcs_are_young(), "sanity");
3900
3901 // We also do not allow mixed GCs during marking.
3902 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3903
3904 // Record whether this pause is an initial mark. When the current
3905 // thread has completed its logging output and it's safe to signal
3906 // the CM thread, the flag's value in the policy has been reset.
3907 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3908
3909 // Inner scope for scope based logging, timers, and stats collection
3910 {
3911 EvacuationInfo evacuation_info;
3912
3913 if (g1_policy()->during_initial_mark_pause()) {
3914 // We are about to start a marking cycle, so we increment the
3915 // full collection counter.
3916 increment_old_marking_cycles_started();
3917 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3918 }
3919
3920 _gc_tracer_stw->report_yc_type(yc_type());
3921
3922 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3923
3924 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3925 workers()->active_workers() : 1);
3926 double pause_start_sec = os::elapsedTime();
3927 g1_policy()->phase_times()->note_gc_start(active_workers);
3928 log_gc_header();
3929
3930 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3931 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3932
3933 // If the secondary_free_list is not empty, append it to the
3934 // free_list. No need to wait for the cleanup operation to finish;
3935 // the region allocation code will check the secondary_free_list
3936 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3937 // set, skip this step so that the region allocation code has to
3938 // get entries from the secondary_free_list.
3939 if (!G1StressConcRegionFreeing) {
3940 append_secondary_free_list_if_not_empty_with_lock();
3941 }
3942
3943 assert(check_young_list_well_formed(), "young list should be well formed");
3944 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3945 "sanity check");
3946
3947 // Don't dynamically change the number of GC threads this early. A value of
3948 // 0 is used to indicate serial work. When parallel work is done,
3949 // it will be set.
3950
3951 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3952 IsGCActiveMark x;
3953
3954 gc_prologue(false);
3955 increment_total_collections(false /* full gc */);
3956 increment_gc_time_stamp();
3957
3958 verify_before_gc();
3959
3960 COMPILER2_PRESENT(DerivedPointerTable::clear());
3961
3962 // Please see comment in g1CollectedHeap.hpp and
3963 // G1CollectedHeap::ref_processing_init() to see how
3964 // reference processing currently works in G1.
3965
3966 // Enable discovery in the STW reference processor
3967 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3968 true /*verify_no_refs*/);
3969
3970 {
3971 // We want to temporarily turn off discovery by the
3972 // CM ref processor, if necessary, and turn it back on
3973 // on again later if we do. Using a scoped
3974 // NoRefDiscovery object will do this.
3975 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3976
3977 // Forget the current alloc region (we might even choose it to be part
3978 // of the collection set!).
3979 release_mutator_alloc_region();
3980
3981 // We should call this after we retire the mutator alloc
3982 // region(s) so that all the ALLOC / RETIRE events are generated
3983 // before the start GC event.
3984 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3985
3986 // This timing is only used by the ergonomics to handle our pause target.
3987 // It is unclear why this should not include the full pause. We will
3988 // investigate this in CR 7178365.
3989 //
3990 // Preserving the old comment here if that helps the investigation:
3991 //
3992 // The elapsed time induced by the start time below deliberately elides
3993 // the possible verification above.
3994 double sample_start_time_sec = os::elapsedTime();
3995
3996 #if YOUNG_LIST_VERBOSE
3997 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3998 _young_list->print();
3999 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4000 #endif // YOUNG_LIST_VERBOSE
4001
4002 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4003
4004 double scan_wait_start = os::elapsedTime();
4005 // We have to wait until the CM threads finish scanning the
4006 // root regions as it's the only way to ensure that all the
4007 // objects on them have been correctly scanned before we start
4008 // moving them during the GC.
4009 bool waited = _cm->root_regions()->wait_until_scan_finished();
4010 double wait_time_ms = 0.0;
4011 if (waited) {
4012 double scan_wait_end = os::elapsedTime();
4013 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4014 }
4015 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4016
4017 #if YOUNG_LIST_VERBOSE
4018 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4019 _young_list->print();
4020 #endif // YOUNG_LIST_VERBOSE
4021
4022 if (g1_policy()->during_initial_mark_pause()) {
4023 concurrent_mark()->checkpointRootsInitialPre();
4024 }
4025
4026 #if YOUNG_LIST_VERBOSE
4027 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4028 _young_list->print();
4029 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4030 #endif // YOUNG_LIST_VERBOSE
4031
4032 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4033
4034 _cm->note_start_of_gc();
4035 // We should not verify the per-thread SATB buffers given that
4036 // we have not filtered them yet (we'll do so during the
4037 // GC). We also call this after finalize_cset() to
4038 // ensure that the CSet has been finalized.
4039 _cm->verify_no_cset_oops(true /* verify_stacks */,
4040 true /* verify_enqueued_buffers */,
4041 false /* verify_thread_buffers */,
4042 true /* verify_fingers */);
4043
4044 if (_hr_printer.is_active()) {
4045 HeapRegion* hr = g1_policy()->collection_set();
4046 while (hr != NULL) {
4047 G1HRPrinter::RegionType type;
4048 if (!hr->is_young()) {
4049 type = G1HRPrinter::Old;
4050 } else if (hr->is_survivor()) {
4051 type = G1HRPrinter::Survivor;
4052 } else {
4053 type = G1HRPrinter::Eden;
4054 }
4055 _hr_printer.cset(hr);
4056 hr = hr->next_in_collection_set();
4057 }
4058 }
4059
4060 #ifdef ASSERT
4061 VerifyCSetClosure cl;
4062 collection_set_iterate(&cl);
4063 #endif // ASSERT
4064
4065 setup_surviving_young_words();
4066
4067 // Initialize the GC alloc regions.
4068 init_gc_alloc_regions(evacuation_info);
4069
4070 // Actually do the work...
4071 evacuate_collection_set(evacuation_info);
4072
4073 // We do this to mainly verify the per-thread SATB buffers
4074 // (which have been filtered by now) since we didn't verify
4075 // them earlier. No point in re-checking the stacks / enqueued
4076 // buffers given that the CSet has not changed since last time
4077 // we checked.
4078 _cm->verify_no_cset_oops(false /* verify_stacks */,
4079 false /* verify_enqueued_buffers */,
4080 true /* verify_thread_buffers */,
4081 true /* verify_fingers */);
4082
4083 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4084 g1_policy()->clear_collection_set();
4085
4086 cleanup_surviving_young_words();
4087
4088 // Start a new incremental collection set for the next pause.
4089 g1_policy()->start_incremental_cset_building();
4090
4091 // Clear the _cset_fast_test bitmap in anticipation of adding
4092 // regions to the incremental collection set for the next
4093 // evacuation pause.
4094 clear_cset_fast_test();
4095
4096 _young_list->reset_sampled_info();
4097
4098 // Don't check the whole heap at this point as the
4099 // GC alloc regions from this pause have been tagged
4100 // as survivors and moved on to the survivor list.
4101 // Survivor regions will fail the !is_young() check.
4102 assert(check_young_list_empty(false /* check_heap */),
4103 "young list should be empty");
4104
4105 #if YOUNG_LIST_VERBOSE
4106 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4107 _young_list->print();
4108 #endif // YOUNG_LIST_VERBOSE
4109
4110 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4111 _young_list->first_survivor_region(),
4112 _young_list->last_survivor_region());
4113
4114 _young_list->reset_auxilary_lists();
4115
4116 if (evacuation_failed()) {
4117 _summary_bytes_used = recalculate_used();
4118 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4119 for (uint i = 0; i < n_queues; i++) {
4120 if (_evacuation_failed_info_array[i].has_failed()) {
4121 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4122 }
4123 }
4124 } else {
4125 // The "used" of the the collection set have already been subtracted
4126 // when they were freed. Add in the bytes evacuated.
4127 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4128 }
4129
4130 if (g1_policy()->during_initial_mark_pause()) {
4131 // We have to do this before we notify the CM threads that
4132 // they can start working to make sure that all the
4133 // appropriate initialization is done on the CM object.
4134 concurrent_mark()->checkpointRootsInitialPost();
4135 set_marking_started();
4136 // Note that we don't actually trigger the CM thread at
4137 // this point. We do that later when we're sure that
4138 // the current thread has completed its logging output.
4139 }
4140
4141 allocate_dummy_regions();
4142
4143 #if YOUNG_LIST_VERBOSE
4144 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4145 _young_list->print();
4146 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4147 #endif // YOUNG_LIST_VERBOSE
4148
4149 init_mutator_alloc_region();
4150
4151 {
4152 size_t expand_bytes = g1_policy()->expansion_amount();
4153 if (expand_bytes > 0) {
4154 size_t bytes_before = capacity();
4155 // No need for an ergo verbose message here,
4156 // expansion_amount() does this when it returns a value > 0.
4157 if (!expand(expand_bytes)) {
4158 // We failed to expand the heap so let's verify that
4159 // committed/uncommitted amount match the backing store
4160 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4161 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4162 }
4163 }
4164 }
4165
4166 // We redo the verification but now wrt to the new CSet which
4167 // has just got initialized after the previous CSet was freed.
4168 _cm->verify_no_cset_oops(true /* verify_stacks */,
4169 true /* verify_enqueued_buffers */,
4170 true /* verify_thread_buffers */,
4171 true /* verify_fingers */);
4172 _cm->note_end_of_gc();
4173
4174 // This timing is only used by the ergonomics to handle our pause target.
4175 // It is unclear why this should not include the full pause. We will
4176 // investigate this in CR 7178365.
4177 double sample_end_time_sec = os::elapsedTime();
4178 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4179 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4180
4181 MemoryService::track_memory_usage();
4182
4183 // In prepare_for_verify() below we'll need to scan the deferred
4184 // update buffers to bring the RSets up-to-date if
4185 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4186 // the update buffers we'll probably need to scan cards on the
4187 // regions we just allocated to (i.e., the GC alloc
4188 // regions). However, during the last GC we called
4189 // set_saved_mark() on all the GC alloc regions, so card
4190 // scanning might skip the [saved_mark_word()...top()] area of
4191 // those regions (i.e., the area we allocated objects into
4192 // during the last GC). But it shouldn't. Given that
4193 // saved_mark_word() is conditional on whether the GC time stamp
4194 // on the region is current or not, by incrementing the GC time
4195 // stamp here we invalidate all the GC time stamps on all the
4196 // regions and saved_mark_word() will simply return top() for
4197 // all the regions. This is a nicer way of ensuring this rather
4198 // than iterating over the regions and fixing them. In fact, the
4199 // GC time stamp increment here also ensures that
4200 // saved_mark_word() will return top() between pauses, i.e.,
4201 // during concurrent refinement. So we don't need the
4202 // is_gc_active() check to decided which top to use when
4203 // scanning cards (see CR 7039627).
4204 increment_gc_time_stamp();
4205
4206 verify_after_gc();
4207
4208 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4209 ref_processor_stw()->verify_no_references_recorded();
4210
4211 // CM reference discovery will be re-enabled if necessary.
4212 }
4213
4214 // We should do this after we potentially expand the heap so
4215 // that all the COMMIT events are generated before the end GC
4216 // event, and after we retire the GC alloc regions so that all
4217 // RETIRE events are generated before the end GC event.
4218 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4219
4220 if (mark_in_progress()) {
4221 concurrent_mark()->update_g1_committed();
4222 }
4223
4224 #ifdef TRACESPINNING
4225 ParallelTaskTerminator::print_termination_counts();
4226 #endif
4227
4228 gc_epilogue(false);
4229 }
4230
4231 // Print the remainder of the GC log output.
4232 log_gc_footer(os::elapsedTime() - pause_start_sec);
4233
4234 // It is not yet to safe to tell the concurrent mark to
4235 // start as we have some optional output below. We don't want the
4236 // output from the concurrent mark thread interfering with this
4237 // logging output either.
4238
4239 _hrs.verify_optional();
4240 verify_region_sets_optional();
4241
4242 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4243 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4244
4245 print_heap_after_gc();
4246 trace_heap_after_gc(_gc_tracer_stw);
4247
4248 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4249 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4250 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4251 // before any GC notifications are raised.
4252 g1mm()->update_sizes();
4253
4254 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4255 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4256 _gc_timer_stw->register_gc_end();
4257 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4258 }
4259 // It should now be safe to tell the concurrent mark thread to start
4260 // without its logging output interfering with the logging output
4261 // that came from the pause.
4262
4263 if (should_start_conc_mark) {
4264 // CAUTION: after the doConcurrentMark() call below,
4265 // the concurrent marking thread(s) could be running
4266 // concurrently with us. Make sure that anything after
4267 // this point does not assume that we are the only GC thread
4268 // running. Note: of course, the actual marking work will
4269 // not start until the safepoint itself is released in
4270 // ConcurrentGCThread::safepoint_desynchronize().
4271 doConcurrentMark();
4272 }
4273
4274 return true;
4275 }
4276
4277 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4278 {
4279 size_t gclab_word_size;
4280 switch (purpose) {
4281 case GCAllocForSurvived:
4282 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4283 break;
4284 case GCAllocForTenured:
4285 gclab_word_size = _old_plab_stats.desired_plab_sz();
4286 break;
4287 default:
4288 assert(false, "unknown GCAllocPurpose");
4289 gclab_word_size = _old_plab_stats.desired_plab_sz();
4290 break;
4291 }
4292
4293 // Prevent humongous PLAB sizes for two reasons:
4294 // * PLABs are allocated using a similar paths as oops, but should
4295 // never be in a humongous region
4296 // * Allowing humongous PLABs needlessly churns the region free lists
4297 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4298 }
4299
4300 void G1CollectedHeap::init_mutator_alloc_region() {
4301 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4302 _mutator_alloc_region.init();
4303 }
4304
4305 void G1CollectedHeap::release_mutator_alloc_region() {
4306 _mutator_alloc_region.release();
4307 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4308 }
4309
4310 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4311 assert_at_safepoint(true /* should_be_vm_thread */);
4312
4313 _survivor_gc_alloc_region.init();
4314 _old_gc_alloc_region.init();
4315 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4316 _retained_old_gc_alloc_region = NULL;
4317
4318 // We will discard the current GC alloc region if:
4319 // a) it's in the collection set (it can happen!),
4320 // b) it's already full (no point in using it),
4321 // c) it's empty (this means that it was emptied during
4322 // a cleanup and it should be on the free list now), or
4323 // d) it's humongous (this means that it was emptied
4324 // during a cleanup and was added to the free list, but
4325 // has been subsequently used to allocate a humongous
4326 // object that may be less than the region size).
4327 if (retained_region != NULL &&
4328 !retained_region->in_collection_set() &&
4329 !(retained_region->top() == retained_region->end()) &&
4330 !retained_region->is_empty() &&
4331 !retained_region->isHumongous()) {
4332 retained_region->set_saved_mark();
4333 // The retained region was added to the old region set when it was
4334 // retired. We have to remove it now, since we don't allow regions
4335 // we allocate to in the region sets. We'll re-add it later, when
4336 // it's retired again.
4337 _old_set.remove(retained_region);
4338 bool during_im = g1_policy()->during_initial_mark_pause();
4339 retained_region->note_start_of_copying(during_im);
4340 _old_gc_alloc_region.set(retained_region);
4341 _hr_printer.reuse(retained_region);
4342 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4343 }
4344 }
4345
4346 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4347 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4348 _old_gc_alloc_region.count());
4349 _survivor_gc_alloc_region.release();
4350 // If we have an old GC alloc region to release, we'll save it in
4351 // _retained_old_gc_alloc_region. If we don't
4352 // _retained_old_gc_alloc_region will become NULL. This is what we
4353 // want either way so no reason to check explicitly for either
4354 // condition.
4355 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4356
4357 if (ResizePLAB) {
4358 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4359 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4360 }
4361 }
4362
4363 void G1CollectedHeap::abandon_gc_alloc_regions() {
4364 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4365 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4366 _retained_old_gc_alloc_region = NULL;
4367 }
4368
4369 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4370 _drain_in_progress = false;
4371 set_evac_failure_closure(cl);
4372 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4373 }
4374
4375 void G1CollectedHeap::finalize_for_evac_failure() {
4376 assert(_evac_failure_scan_stack != NULL &&
4377 _evac_failure_scan_stack->length() == 0,
4378 "Postcondition");
4379 assert(!_drain_in_progress, "Postcondition");
4380 delete _evac_failure_scan_stack;
4381 _evac_failure_scan_stack = NULL;
4382 }
4383
4384 void G1CollectedHeap::remove_self_forwarding_pointers() {
4385 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4386
4387 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4388
4389 if (G1CollectedHeap::use_parallel_gc_threads()) {
4390 set_par_threads();
4391 workers()->run_task(&rsfp_task);
4392 set_par_threads(0);
4393 } else {
4394 rsfp_task.work(0);
4395 }
4396
4397 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4398
4399 // Reset the claim values in the regions in the collection set.
4400 reset_cset_heap_region_claim_values();
4401
4402 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4403
4404 // Now restore saved marks, if any.
4405 assert(_objs_with_preserved_marks.size() ==
4406 _preserved_marks_of_objs.size(), "Both or none.");
4407 while (!_objs_with_preserved_marks.is_empty()) {
4408 oop obj = _objs_with_preserved_marks.pop();
4409 markOop m = _preserved_marks_of_objs.pop();
4410 obj->set_mark(m);
4411 }
4412 _objs_with_preserved_marks.clear(true);
4413 _preserved_marks_of_objs.clear(true);
4414 }
4415
4416 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4417 _evac_failure_scan_stack->push(obj);
4418 }
4419
4420 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4421 assert(_evac_failure_scan_stack != NULL, "precondition");
4422
4423 while (_evac_failure_scan_stack->length() > 0) {
4424 oop obj = _evac_failure_scan_stack->pop();
4425 _evac_failure_closure->set_region(heap_region_containing(obj));
4426 obj->oop_iterate_backwards(_evac_failure_closure);
4427 }
4428 }
4429
4430 oop
4431 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4432 oop old) {
4433 assert(obj_in_cs(old),
4434 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4435 (HeapWord*) old));
4436 markOop m = old->mark();
4437 oop forward_ptr = old->forward_to_atomic(old);
4438 if (forward_ptr == NULL) {
4439 // Forward-to-self succeeded.
4440 assert(_par_scan_state != NULL, "par scan state");
4441 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4442 uint queue_num = _par_scan_state->queue_num();
4443
4444 _evacuation_failed = true;
4445 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4446 if (_evac_failure_closure != cl) {
4447 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4448 assert(!_drain_in_progress,
4449 "Should only be true while someone holds the lock.");
4450 // Set the global evac-failure closure to the current thread's.
4451 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4452 set_evac_failure_closure(cl);
4453 // Now do the common part.
4454 handle_evacuation_failure_common(old, m);
4455 // Reset to NULL.
4456 set_evac_failure_closure(NULL);
4457 } else {
4458 // The lock is already held, and this is recursive.
4459 assert(_drain_in_progress, "This should only be the recursive case.");
4460 handle_evacuation_failure_common(old, m);
4461 }
4462 return old;
4463 } else {
4464 // Forward-to-self failed. Either someone else managed to allocate
4465 // space for this object (old != forward_ptr) or they beat us in
4466 // self-forwarding it (old == forward_ptr).
4467 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4468 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4469 "should not be in the CSet",
4470 (HeapWord*) old, (HeapWord*) forward_ptr));
4471 return forward_ptr;
4472 }
4473 }
4474
4475 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4476 preserve_mark_if_necessary(old, m);
4477
4478 HeapRegion* r = heap_region_containing(old);
4479 if (!r->evacuation_failed()) {
4480 r->set_evacuation_failed(true);
4481 _hr_printer.evac_failure(r);
4482 }
4483
4484 push_on_evac_failure_scan_stack(old);
4485
4486 if (!_drain_in_progress) {
4487 // prevent recursion in copy_to_survivor_space()
4488 _drain_in_progress = true;
4489 drain_evac_failure_scan_stack();
4490 _drain_in_progress = false;
4491 }
4492 }
4493
4494 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4495 assert(evacuation_failed(), "Oversaving!");
4496 // We want to call the "for_promotion_failure" version only in the
4497 // case of a promotion failure.
4498 if (m->must_be_preserved_for_promotion_failure(obj)) {
4499 _objs_with_preserved_marks.push(obj);
4500 _preserved_marks_of_objs.push(m);
4501 }
4502 }
4503
4504 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4505 size_t word_size) {
4506 if (purpose == GCAllocForSurvived) {
4507 HeapWord* result = survivor_attempt_allocation(word_size);
4508 if (result != NULL) {
4509 return result;
4510 } else {
4511 // Let's try to allocate in the old gen in case we can fit the
4512 // object there.
4513 return old_attempt_allocation(word_size);
4514 }
4515 } else {
4516 assert(purpose == GCAllocForTenured, "sanity");
4517 HeapWord* result = old_attempt_allocation(word_size);
4518 if (result != NULL) {
4519 return result;
4520 } else {
4521 // Let's try to allocate in the survivors in case we can fit the
4522 // object there.
4523 return survivor_attempt_allocation(word_size);
4524 }
4525 }
4526
4527 ShouldNotReachHere();
4528 // Trying to keep some compilers happy.
4529 return NULL;
4530 }
4531
4532 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4533 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4534
4535 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4536 : _g1h(g1h),
4537 _refs(g1h->task_queue(queue_num)),
4538 _dcq(&g1h->dirty_card_queue_set()),
4539 _ct_bs(g1h->g1_barrier_set()),
4540 _g1_rem(g1h->g1_rem_set()),
4541 _hash_seed(17), _queue_num(queue_num),
4542 _term_attempts(0),
4543 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4544 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4545 _age_table(false), _scanner(g1h, this, rp),
4546 _strong_roots_time(0), _term_time(0),
4547 _alloc_buffer_waste(0), _undo_waste(0) {
4548 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4549 // we "sacrifice" entry 0 to keep track of surviving bytes for
4550 // non-young regions (where the age is -1)
4551 // We also add a few elements at the beginning and at the end in
4552 // an attempt to eliminate cache contention
4553 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4554 uint array_length = PADDING_ELEM_NUM +
4555 real_length +
4556 PADDING_ELEM_NUM;
4557 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4558 if (_surviving_young_words_base == NULL)
4559 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4560 "Not enough space for young surv histo.");
4561 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4562 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4563
4564 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4565 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4566
4567 _start = os::elapsedTime();
4568 }
4569
4570 void
4571 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4572 {
4573 st->print_raw_cr("GC Termination Stats");
4574 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4575 " ------waste (KiB)------");
4576 st->print_raw_cr("thr ms ms % ms % attempts"
4577 " total alloc undo");
4578 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4579 " ------- ------- -------");
4580 }
4581
4582 void
4583 G1ParScanThreadState::print_termination_stats(int i,
4584 outputStream* const st) const
4585 {
4586 const double elapsed_ms = elapsed_time() * 1000.0;
4587 const double s_roots_ms = strong_roots_time() * 1000.0;
4588 const double term_ms = term_time() * 1000.0;
4589 st->print_cr("%3d %9.2f %9.2f %6.2f "
4590 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4591 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4592 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4593 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4594 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4595 alloc_buffer_waste() * HeapWordSize / K,
4596 undo_waste() * HeapWordSize / K);
4597 }
4598
4599 #ifdef ASSERT
4600 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4601 assert(ref != NULL, "invariant");
4602 assert(UseCompressedOops, "sanity");
4603 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4604 oop p = oopDesc::load_decode_heap_oop(ref);
4605 assert(_g1h->is_in_g1_reserved(p),
4606 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4607 return true;
4608 }
4609
4610 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4611 assert(ref != NULL, "invariant");
4612 if (has_partial_array_mask(ref)) {
4613 // Must be in the collection set--it's already been copied.
4614 oop p = clear_partial_array_mask(ref);
4615 assert(_g1h->obj_in_cs(p),
4616 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4617 } else {
4618 oop p = oopDesc::load_decode_heap_oop(ref);
4619 assert(_g1h->is_in_g1_reserved(p),
4620 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4621 }
4622 return true;
4623 }
4624
4625 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4626 if (ref.is_narrow()) {
4627 return verify_ref((narrowOop*) ref);
4628 } else {
4629 return verify_ref((oop*) ref);
4630 }
4631 }
4632 #endif // ASSERT
4633
4634 void G1ParScanThreadState::trim_queue() {
4635 assert(_evac_cl != NULL, "not set");
4636 assert(_evac_failure_cl != NULL, "not set");
4637 assert(_partial_scan_cl != NULL, "not set");
4638
4639 StarTask ref;
4640 do {
4641 // Drain the overflow stack first, so other threads can steal.
4642 while (refs()->pop_overflow(ref)) {
4643 deal_with_reference(ref);
4644 }
4645
4646 while (refs()->pop_local(ref)) {
4647 deal_with_reference(ref);
4648 }
4649 } while (!refs()->is_empty());
4650 }
4651
4652 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4653 G1ParScanThreadState* par_scan_state) :
4654 _g1(g1), _par_scan_state(par_scan_state),
4655 _worker_id(par_scan_state->queue_num()) { }
4656
4657 void G1ParCopyHelper::mark_object(oop obj) {
4658 #ifdef ASSERT
4659 HeapRegion* hr = _g1->heap_region_containing(obj);
4660 assert(hr != NULL, "sanity");
4661 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4662 #endif // ASSERT
4663
4664 // We know that the object is not moving so it's safe to read its size.
4665 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4666 }
4667
4668 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4669 #ifdef ASSERT
4670 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4671 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4672 assert(from_obj != to_obj, "should not be self-forwarded");
4673
4674 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4675 assert(from_hr != NULL, "sanity");
4676 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4677
4678 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4679 assert(to_hr != NULL, "sanity");
4680 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4681 #endif // ASSERT
4682
4683 // The object might be in the process of being copied by another
4684 // worker so we cannot trust that its to-space image is
4685 // well-formed. So we have to read its size from its from-space
4686 // image which we know should not be changing.
4687 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4688 }
4689
4690 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4691 size_t word_sz = old->size();
4692 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4693 // +1 to make the -1 indexes valid...
4694 int young_index = from_region->young_index_in_cset()+1;
4695 assert( (from_region->is_young() && young_index > 0) ||
4696 (!from_region->is_young() && young_index == 0), "invariant" );
4697 G1CollectorPolicy* g1p = _g1h->g1_policy();
4698 markOop m = old->mark();
4699 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4700 : m->age();
4701 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4702 word_sz);
4703 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4704 #ifndef PRODUCT
4705 // Should this evacuation fail?
4706 if (_g1h->evacuation_should_fail()) {
4707 if (obj_ptr != NULL) {
4708 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4709 obj_ptr = NULL;
4710 }
4711 }
4712 #endif // !PRODUCT
4713
4714 if (obj_ptr == NULL) {
4715 // This will either forward-to-self, or detect that someone else has
4716 // installed a forwarding pointer.
4717 return _g1h->handle_evacuation_failure_par(this, old);
4718 }
4719
4720 oop obj = oop(obj_ptr);
4721
4722 // We're going to allocate linearly, so might as well prefetch ahead.
4723 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4724
4725 oop forward_ptr = old->forward_to_atomic(obj);
4726 if (forward_ptr == NULL) {
4727 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4728
4729 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4730 // we actually allocated from and update alloc_purpose accordingly
4731 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4732 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4733
4734 if (g1p->track_object_age(alloc_purpose)) {
4735 // We could simply do obj->incr_age(). However, this causes a
4736 // performance issue. obj->incr_age() will first check whether
4737 // the object has a displaced mark by checking its mark word;
4738 // getting the mark word from the new location of the object
4739 // stalls. So, given that we already have the mark word and we
4740 // are about to install it anyway, it's better to increase the
4741 // age on the mark word, when the object does not have a
4742 // displaced mark word. We're not expecting many objects to have
4743 // a displaced marked word, so that case is not optimized
4744 // further (it could be...) and we simply call obj->incr_age().
4745
4746 if (m->has_displaced_mark_helper()) {
4747 // in this case, we have to install the mark word first,
4748 // otherwise obj looks to be forwarded (the old mark word,
4749 // which contains the forward pointer, was copied)
4750 obj->set_mark(m);
4751 obj->incr_age();
4752 } else {
4753 m = m->incr_age();
4754 obj->set_mark(m);
4755 }
4756 age_table()->add(obj, word_sz);
4757 } else {
4758 obj->set_mark(m);
4759 }
4760
4761 size_t* surv_young_words = surviving_young_words();
4762 surv_young_words[young_index] += word_sz;
4763
4764 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4765 // We keep track of the next start index in the length field of
4766 // the to-space object. The actual length can be found in the
4767 // length field of the from-space object.
4768 arrayOop(obj)->set_length(0);
4769 oop* old_p = set_partial_array_mask(old);
4770 push_on_queue(old_p);
4771 } else {
4772 // No point in using the slower heap_region_containing() method,
4773 // given that we know obj is in the heap.
4774 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4775 obj->oop_iterate_backwards(&_scanner);
4776 }
4777 } else {
4778 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4779 obj = forward_ptr;
4780 }
4781 return obj;
4782 }
4783
4784 template <class T>
4785 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4786 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4787 _scanned_klass->record_modified_oops();
4788 }
4789 }
4790
4791 template <G1Barrier barrier, bool do_mark_object>
4792 template <class T>
4793 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4794 T heap_oop = oopDesc::load_heap_oop(p);
4795
4796 if (oopDesc::is_null(heap_oop)) {
4797 return;
4798 }
4799
4800 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4801
4802 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4803
4804 if (_g1->in_cset_fast_test(obj)) {
4805 oop forwardee;
4806 if (obj->is_forwarded()) {
4807 forwardee = obj->forwardee();
4808 } else {
4809 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4810 }
4811 assert(forwardee != NULL, "forwardee should not be NULL");
4812 oopDesc::encode_store_heap_oop(p, forwardee);
4813 if (do_mark_object && forwardee != obj) {
4814 // If the object is self-forwarded we don't need to explicitly
4815 // mark it, the evacuation failure protocol will do so.
4816 mark_forwarded_object(obj, forwardee);
4817 }
4818
4819 if (barrier == G1BarrierKlass) {
4820 do_klass_barrier(p, forwardee);
4821 }
4822 } else {
4823 // The object is not in collection set. If we're a root scanning
4824 // closure during an initial mark pause (i.e. do_mark_object will
4825 // be true) then attempt to mark the object.
4826 if (do_mark_object) {
4827 mark_object(obj);
4828 }
4829 }
4830
4831 if (barrier == G1BarrierEvac) {
4832 _par_scan_state->update_rs(_from, p, _worker_id);
4833 }
4834 }
4835
4836 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4837 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4838
4839 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4840 assert(has_partial_array_mask(p), "invariant");
4841 oop from_obj = clear_partial_array_mask(p);
4842
4843 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4844 assert(from_obj->is_objArray(), "must be obj array");
4845 objArrayOop from_obj_array = objArrayOop(from_obj);
4846 // The from-space object contains the real length.
4847 int length = 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 // We keep track of the next start index in the length field of the
4854 // to-space object.
4855 int next_index = to_obj_array->length();
4856 assert(0 <= next_index && next_index < length,
4857 err_msg("invariant, next index: %d, length: %d", next_index, length));
4858
4859 int start = next_index;
4860 int end = length;
4861 int remainder = end - start;
4862 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4863 if (remainder > 2 * ParGCArrayScanChunk) {
4864 end = start + ParGCArrayScanChunk;
4865 to_obj_array->set_length(end);
4866 // Push the remainder before we process the range in case another
4867 // worker has run out of things to do and can steal it.
4868 oop* from_obj_p = set_partial_array_mask(from_obj);
4869 _par_scan_state->push_on_queue(from_obj_p);
4870 } else {
4871 assert(length == end, "sanity");
4872 // We'll process the final range for this object. Restore the length
4873 // so that the heap remains parsable in case of evacuation failure.
4874 to_obj_array->set_length(end);
4875 }
4876 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4877 // Process indexes [start,end). It will also process the header
4878 // along with the first chunk (i.e., the chunk with start == 0).
4879 // Note that at this point the length field of to_obj_array is not
4880 // correct given that we are using it to keep track of the next
4881 // start index. oop_iterate_range() (thankfully!) ignores the length
4882 // field and only relies on the start / end parameters. It does
4883 // however return the size of the object which will be incorrect. So
4884 // we have to ignore it even if we wanted to use it.
4885 to_obj_array->oop_iterate_range(&_scanner, start, end);
4886 }
4887
4888 class G1ParEvacuateFollowersClosure : public VoidClosure {
4889 protected:
4890 G1CollectedHeap* _g1h;
4891 G1ParScanThreadState* _par_scan_state;
4892 RefToScanQueueSet* _queues;
4893 ParallelTaskTerminator* _terminator;
4894
4895 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4896 RefToScanQueueSet* queues() { return _queues; }
4897 ParallelTaskTerminator* terminator() { return _terminator; }
4898
4899 public:
4900 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4901 G1ParScanThreadState* par_scan_state,
4902 RefToScanQueueSet* queues,
4903 ParallelTaskTerminator* terminator)
4904 : _g1h(g1h), _par_scan_state(par_scan_state),
4905 _queues(queues), _terminator(terminator) {}
4906
4907 void do_void();
4908
4909 private:
4910 inline bool offer_termination();
4911 };
4912
4913 bool G1ParEvacuateFollowersClosure::offer_termination() {
4914 G1ParScanThreadState* const pss = par_scan_state();
4915 pss->start_term_time();
4916 const bool res = terminator()->offer_termination();
4917 pss->end_term_time();
4918 return res;
4919 }
4920
4921 void G1ParEvacuateFollowersClosure::do_void() {
4922 StarTask stolen_task;
4923 G1ParScanThreadState* const pss = par_scan_state();
4924 pss->trim_queue();
4925
4926 do {
4927 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4928 assert(pss->verify_task(stolen_task), "sanity");
4929 if (stolen_task.is_narrow()) {
4930 pss->deal_with_reference((narrowOop*) stolen_task);
4931 } else {
4932 pss->deal_with_reference((oop*) stolen_task);
4933 }
4934
4935 // We've just processed a reference and we might have made
4936 // available new entries on the queues. So we have to make sure
4937 // we drain the queues as necessary.
4938 pss->trim_queue();
4939 }
4940 } while (!offer_termination());
4941
4942 pss->retire_alloc_buffers();
4943 }
4944
4945 class G1KlassScanClosure : public KlassClosure {
4946 G1ParCopyHelper* _closure;
4947 bool _process_only_dirty;
4948 int _count;
4949 public:
4950 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4951 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4952 void do_klass(Klass* klass) {
4953 // If the klass has not been dirtied we know that there's
4954 // no references into the young gen and we can skip it.
4955 if (!_process_only_dirty || klass->has_modified_oops()) {
4956 // Clean the klass since we're going to scavenge all the metadata.
4957 klass->clear_modified_oops();
4958
4959 // Tell the closure that this klass is the Klass to scavenge
4960 // and is the one to dirty if oops are left pointing into the young gen.
4961 _closure->set_scanned_klass(klass);
4962
4963 klass->oops_do(_closure);
4964
4965 _closure->set_scanned_klass(NULL);
4966 }
4967 _count++;
4968 }
4969 };
4970
4971 class G1ParTask : public AbstractGangTask {
4972 protected:
4973 G1CollectedHeap* _g1h;
4974 RefToScanQueueSet *_queues;
4975 ParallelTaskTerminator _terminator;
4976 uint _n_workers;
4977
4978 Mutex _stats_lock;
4979 Mutex* stats_lock() { return &_stats_lock; }
4980
4981 size_t getNCards() {
4982 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4983 / G1BlockOffsetSharedArray::N_bytes;
4984 }
4985
4986 public:
4987 G1ParTask(G1CollectedHeap* g1h,
4988 RefToScanQueueSet *task_queues)
4989 : AbstractGangTask("G1 collection"),
4990 _g1h(g1h),
4991 _queues(task_queues),
4992 _terminator(0, _queues),
4993 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4994 {}
4995
4996 RefToScanQueueSet* queues() { return _queues; }
4997
4998 RefToScanQueue *work_queue(int i) {
4999 return queues()->queue(i);
5000 }
5001
5002 ParallelTaskTerminator* terminator() { return &_terminator; }
5003
5004 virtual void set_for_termination(int active_workers) {
5005 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5006 // in the young space (_par_seq_tasks) in the G1 heap
5007 // for SequentialSubTasksDone.
5008 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5009 // both of which need setting by set_n_termination().
5010 _g1h->SharedHeap::set_n_termination(active_workers);
5011 _g1h->set_n_termination(active_workers);
5012 terminator()->reset_for_reuse(active_workers);
5013 _n_workers = active_workers;
5014 }
5015
5016 void work(uint worker_id) {
5017 if (worker_id >= _n_workers) return; // no work needed this round
5018
5019 double start_time_ms = os::elapsedTime() * 1000.0;
5020 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5021
5022 {
5023 ResourceMark rm;
5024 HandleMark hm;
5025
5026 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5027
5028 G1ParScanThreadState pss(_g1h, worker_id, rp);
5029 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5030 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5031 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5032
5033 pss.set_evac_closure(&scan_evac_cl);
5034 pss.set_evac_failure_closure(&evac_failure_cl);
5035 pss.set_partial_scan_closure(&partial_scan_cl);
5036
5037 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5038 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5039
5040 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5041 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5042
5043 bool only_young = _g1h->g1_policy()->gcs_are_young();
5044 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5045 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5046
5047 OopClosure* scan_root_cl = &only_scan_root_cl;
5048 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5049
5050 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5051 // We also need to mark copied objects.
5052 scan_root_cl = &scan_mark_root_cl;
5053 scan_klasses_cl = &scan_mark_klasses_cl_s;
5054 }
5055
5056 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5057
5058 // Don't scan the scavengable methods in the code cache as part
5059 // of strong root scanning. The code roots that point into a
5060 // region in the collection set are scanned when we scan the
5061 // region's RSet.
5062 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5063
5064 pss.start_strong_roots();
5065 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5066 SharedHeap::ScanningOption(so),
5067 scan_root_cl,
5068 &push_heap_rs_cl,
5069 scan_klasses_cl,
5070 worker_id);
5071 pss.end_strong_roots();
5072
5073 {
5074 double start = os::elapsedTime();
5075 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5076 evac.do_void();
5077 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5078 double term_ms = pss.term_time()*1000.0;
5079 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5080 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5081 }
5082 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5083 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5084
5085 if (ParallelGCVerbose) {
5086 MutexLocker x(stats_lock());
5087 pss.print_termination_stats(worker_id);
5088 }
5089
5090 assert(pss.refs()->is_empty(), "should be empty");
5091
5092 // Close the inner scope so that the ResourceMark and HandleMark
5093 // destructors are executed here and are included as part of the
5094 // "GC Worker Time".
5095 }
5096
5097 double end_time_ms = os::elapsedTime() * 1000.0;
5098 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5099 }
5100 };
5101
5102 // *** Common G1 Evacuation Stuff
5103
5104 // This method is run in a GC worker.
5105
5106 void
5107 G1CollectedHeap::
5108 g1_process_strong_roots(bool is_scavenging,
5109 ScanningOption so,
5110 OopClosure* scan_non_heap_roots,
5111 OopsInHeapRegionClosure* scan_rs,
5112 G1KlassScanClosure* scan_klasses,
5113 int worker_i) {
5114
5115 // First scan the strong roots
5116 double ext_roots_start = os::elapsedTime();
5117 double closure_app_time_sec = 0.0;
5118
5119 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5120
5121 process_strong_roots(false, // no scoping; this is parallel code
5122 so,
5123 &buf_scan_non_heap_roots,
5124 scan_klasses
5125 );
5126
5127 // Now the CM ref_processor roots.
5128 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5129 // We need to treat the discovered reference lists of the
5130 // concurrent mark ref processor as roots and keep entries
5131 // (which are added by the marking threads) on them live
5132 // until they can be processed at the end of marking.
5133 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5134 }
5135
5136 // Finish up any enqueued closure apps (attributed as object copy time).
5137 buf_scan_non_heap_roots.done();
5138
5139 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5140
5141 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5142
5143 double ext_root_time_ms =
5144 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5145
5146 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5147
5148 // During conc marking we have to filter the per-thread SATB buffers
5149 // to make sure we remove any oops into the CSet (which will show up
5150 // as implicitly live).
5151 double satb_filtering_ms = 0.0;
5152 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5153 if (mark_in_progress()) {
5154 double satb_filter_start = os::elapsedTime();
5155
5156 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5157
5158 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5159 }
5160 }
5161 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5162
5163 // If this is an initial mark pause, and we're not scanning
5164 // the entire code cache, we need to mark the oops in the
5165 // strong code root lists for the regions that are not in
5166 // the collection set.
5167 // Note all threads participate in this set of root tasks.
5168 double mark_strong_code_roots_ms = 0.0;
5169 if (g1_policy()->during_initial_mark_pause() && !(so & SO_AllCodeCache)) {
5170 double mark_strong_roots_start = os::elapsedTime();
5171 mark_strong_code_roots(worker_i);
5172 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5173 }
5174 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5175
5176 // Now scan the complement of the collection set.
5177 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5178 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5179
5180 _process_strong_tasks->all_tasks_completed();
5181 }
5182
5183 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5184 private:
5185 BoolObjectClosure* _is_alive;
5186 int _initial_string_table_size;
5187 int _initial_symbol_table_size;
5188
5189 bool _process_strings;
5190 int _strings_processed;
5191 int _strings_removed;
5192
5193 bool _process_symbols;
5194 int _symbols_processed;
5195 int _symbols_removed;
5196
5197 bool _do_in_parallel;
5198 public:
5199 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5200 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5201 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5202 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5203 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5204
5205 _initial_string_table_size = StringTable::the_table()->table_size();
5206 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5207 if (process_strings) {
5208 StringTable::clear_parallel_claimed_index();
5209 }
5210 if (process_symbols) {
5211 SymbolTable::clear_parallel_claimed_index();
5212 }
5213 }
5214
5215 ~G1StringSymbolTableUnlinkTask() {
5216 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5217 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5218 StringTable::parallel_claimed_index(), _initial_string_table_size));
5219 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5220 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5221 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5222 }
5223
5224 void work(uint worker_id) {
5225 if (_do_in_parallel) {
5226 int strings_processed = 0;
5227 int strings_removed = 0;
5228 int symbols_processed = 0;
5229 int symbols_removed = 0;
5230 if (_process_strings) {
5231 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5232 Atomic::add(strings_processed, &_strings_processed);
5233 Atomic::add(strings_removed, &_strings_removed);
5234 }
5235 if (_process_symbols) {
5236 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5237 Atomic::add(symbols_processed, &_symbols_processed);
5238 Atomic::add(symbols_removed, &_symbols_removed);
5239 }
5240 } else {
5241 if (_process_strings) {
5242 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5243 }
5244 if (_process_symbols) {
5245 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5246 }
5247 }
5248 }
5249
5250 size_t strings_processed() const { return (size_t)_strings_processed; }
5251 size_t strings_removed() const { return (size_t)_strings_removed; }
5252
5253 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5254 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5255 };
5256
5257 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5258 bool process_strings, bool process_symbols) {
5259 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5260 _g1h->workers()->active_workers() : 1);
5261
5262 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5263 if (G1CollectedHeap::use_parallel_gc_threads()) {
5264 set_par_threads(n_workers);
5265 workers()->run_task(&g1_unlink_task);
5266 set_par_threads(0);
5267 } else {
5268 g1_unlink_task.work(0);
5269 }
5270 if (G1TraceStringSymbolTableScrubbing) {
5271 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5272 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5273 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5274 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5275 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5276 }
5277 }
5278
5279 // Weak Reference Processing support
5280
5281 // An always "is_alive" closure that is used to preserve referents.
5282 // If the object is non-null then it's alive. Used in the preservation
5283 // of referent objects that are pointed to by reference objects
5284 // discovered by the CM ref processor.
5285 class G1AlwaysAliveClosure: public BoolObjectClosure {
5286 G1CollectedHeap* _g1;
5287 public:
5288 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5289 bool do_object_b(oop p) {
5290 if (p != NULL) {
5291 return true;
5292 }
5293 return false;
5294 }
5295 };
5296
5297 bool G1STWIsAliveClosure::do_object_b(oop p) {
5298 // An object is reachable if it is outside the collection set,
5299 // or is inside and copied.
5300 return !_g1->obj_in_cs(p) || p->is_forwarded();
5301 }
5302
5303 // Non Copying Keep Alive closure
5304 class G1KeepAliveClosure: public OopClosure {
5305 G1CollectedHeap* _g1;
5306 public:
5307 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5308 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5309 void do_oop( oop* p) {
5310 oop obj = *p;
5311
5312 if (_g1->obj_in_cs(obj)) {
5313 assert( obj->is_forwarded(), "invariant" );
5314 *p = obj->forwardee();
5315 }
5316 }
5317 };
5318
5319 // Copying Keep Alive closure - can be called from both
5320 // serial and parallel code as long as different worker
5321 // threads utilize different G1ParScanThreadState instances
5322 // and different queues.
5323
5324 class G1CopyingKeepAliveClosure: public OopClosure {
5325 G1CollectedHeap* _g1h;
5326 OopClosure* _copy_non_heap_obj_cl;
5327 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5328 G1ParScanThreadState* _par_scan_state;
5329
5330 public:
5331 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5332 OopClosure* non_heap_obj_cl,
5333 OopsInHeapRegionClosure* metadata_obj_cl,
5334 G1ParScanThreadState* pss):
5335 _g1h(g1h),
5336 _copy_non_heap_obj_cl(non_heap_obj_cl),
5337 _copy_metadata_obj_cl(metadata_obj_cl),
5338 _par_scan_state(pss)
5339 {}
5340
5341 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5342 virtual void do_oop( oop* p) { do_oop_work(p); }
5343
5344 template <class T> void do_oop_work(T* p) {
5345 oop obj = oopDesc::load_decode_heap_oop(p);
5346
5347 if (_g1h->obj_in_cs(obj)) {
5348 // If the referent object has been forwarded (either copied
5349 // to a new location or to itself in the event of an
5350 // evacuation failure) then we need to update the reference
5351 // field and, if both reference and referent are in the G1
5352 // heap, update the RSet for the referent.
5353 //
5354 // If the referent has not been forwarded then we have to keep
5355 // it alive by policy. Therefore we have copy the referent.
5356 //
5357 // If the reference field is in the G1 heap then we can push
5358 // on the PSS queue. When the queue is drained (after each
5359 // phase of reference processing) the object and it's followers
5360 // will be copied, the reference field set to point to the
5361 // new location, and the RSet updated. Otherwise we need to
5362 // use the the non-heap or metadata closures directly to copy
5363 // the referent object and update the pointer, while avoiding
5364 // updating the RSet.
5365
5366 if (_g1h->is_in_g1_reserved(p)) {
5367 _par_scan_state->push_on_queue(p);
5368 } else {
5369 assert(!ClassLoaderDataGraph::contains((address)p),
5370 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5371 PTR_FORMAT, p));
5372 _copy_non_heap_obj_cl->do_oop(p);
5373 }
5374 }
5375 }
5376 };
5377
5378 // Serial drain queue closure. Called as the 'complete_gc'
5379 // closure for each discovered list in some of the
5380 // reference processing phases.
5381
5382 class G1STWDrainQueueClosure: public VoidClosure {
5383 protected:
5384 G1CollectedHeap* _g1h;
5385 G1ParScanThreadState* _par_scan_state;
5386
5387 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5388
5389 public:
5390 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5391 _g1h(g1h),
5392 _par_scan_state(pss)
5393 { }
5394
5395 void do_void() {
5396 G1ParScanThreadState* const pss = par_scan_state();
5397 pss->trim_queue();
5398 }
5399 };
5400
5401 // Parallel Reference Processing closures
5402
5403 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5404 // processing during G1 evacuation pauses.
5405
5406 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5407 private:
5408 G1CollectedHeap* _g1h;
5409 RefToScanQueueSet* _queues;
5410 FlexibleWorkGang* _workers;
5411 int _active_workers;
5412
5413 public:
5414 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5415 FlexibleWorkGang* workers,
5416 RefToScanQueueSet *task_queues,
5417 int n_workers) :
5418 _g1h(g1h),
5419 _queues(task_queues),
5420 _workers(workers),
5421 _active_workers(n_workers)
5422 {
5423 assert(n_workers > 0, "shouldn't call this otherwise");
5424 }
5425
5426 // Executes the given task using concurrent marking worker threads.
5427 virtual void execute(ProcessTask& task);
5428 virtual void execute(EnqueueTask& task);
5429 };
5430
5431 // Gang task for possibly parallel reference processing
5432
5433 class G1STWRefProcTaskProxy: public AbstractGangTask {
5434 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5435 ProcessTask& _proc_task;
5436 G1CollectedHeap* _g1h;
5437 RefToScanQueueSet *_task_queues;
5438 ParallelTaskTerminator* _terminator;
5439
5440 public:
5441 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5442 G1CollectedHeap* g1h,
5443 RefToScanQueueSet *task_queues,
5444 ParallelTaskTerminator* terminator) :
5445 AbstractGangTask("Process reference objects in parallel"),
5446 _proc_task(proc_task),
5447 _g1h(g1h),
5448 _task_queues(task_queues),
5449 _terminator(terminator)
5450 {}
5451
5452 virtual void work(uint worker_id) {
5453 // The reference processing task executed by a single worker.
5454 ResourceMark rm;
5455 HandleMark hm;
5456
5457 G1STWIsAliveClosure is_alive(_g1h);
5458
5459 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5460
5461 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5462 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5463 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5464
5465 pss.set_evac_closure(&scan_evac_cl);
5466 pss.set_evac_failure_closure(&evac_failure_cl);
5467 pss.set_partial_scan_closure(&partial_scan_cl);
5468
5469 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5470 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5471
5472 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5473 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5474
5475 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5476 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5477
5478 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5479 // We also need to mark copied objects.
5480 copy_non_heap_cl = ©_mark_non_heap_cl;
5481 copy_metadata_cl = ©_mark_metadata_cl;
5482 }
5483
5484 // Keep alive closure.
5485 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5486
5487 // Complete GC closure
5488 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5489
5490 // Call the reference processing task's work routine.
5491 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5492
5493 // Note we cannot assert that the refs array is empty here as not all
5494 // of the processing tasks (specifically phase2 - pp2_work) execute
5495 // the complete_gc closure (which ordinarily would drain the queue) so
5496 // the queue may not be empty.
5497 }
5498 };
5499
5500 // Driver routine for parallel reference processing.
5501 // Creates an instance of the ref processing gang
5502 // task and has the worker threads execute it.
5503 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5504 assert(_workers != NULL, "Need parallel worker threads.");
5505
5506 ParallelTaskTerminator terminator(_active_workers, _queues);
5507 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5508
5509 _g1h->set_par_threads(_active_workers);
5510 _workers->run_task(&proc_task_proxy);
5511 _g1h->set_par_threads(0);
5512 }
5513
5514 // Gang task for parallel reference enqueueing.
5515
5516 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5517 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5518 EnqueueTask& _enq_task;
5519
5520 public:
5521 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5522 AbstractGangTask("Enqueue reference objects in parallel"),
5523 _enq_task(enq_task)
5524 { }
5525
5526 virtual void work(uint worker_id) {
5527 _enq_task.work(worker_id);
5528 }
5529 };
5530
5531 // Driver routine for parallel reference enqueueing.
5532 // Creates an instance of the ref enqueueing gang
5533 // task and has the worker threads execute it.
5534
5535 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5536 assert(_workers != NULL, "Need parallel worker threads.");
5537
5538 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5539
5540 _g1h->set_par_threads(_active_workers);
5541 _workers->run_task(&enq_task_proxy);
5542 _g1h->set_par_threads(0);
5543 }
5544
5545 // End of weak reference support closures
5546
5547 // Abstract task used to preserve (i.e. copy) any referent objects
5548 // that are in the collection set and are pointed to by reference
5549 // objects discovered by the CM ref processor.
5550
5551 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5552 protected:
5553 G1CollectedHeap* _g1h;
5554 RefToScanQueueSet *_queues;
5555 ParallelTaskTerminator _terminator;
5556 uint _n_workers;
5557
5558 public:
5559 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5560 AbstractGangTask("ParPreserveCMReferents"),
5561 _g1h(g1h),
5562 _queues(task_queues),
5563 _terminator(workers, _queues),
5564 _n_workers(workers)
5565 { }
5566
5567 void work(uint worker_id) {
5568 ResourceMark rm;
5569 HandleMark hm;
5570
5571 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5572 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5573 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5574 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5575
5576 pss.set_evac_closure(&scan_evac_cl);
5577 pss.set_evac_failure_closure(&evac_failure_cl);
5578 pss.set_partial_scan_closure(&partial_scan_cl);
5579
5580 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5581
5582
5583 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5584 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5585
5586 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5587 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5588
5589 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5590 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5591
5592 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5593 // We also need to mark copied objects.
5594 copy_non_heap_cl = ©_mark_non_heap_cl;
5595 copy_metadata_cl = ©_mark_metadata_cl;
5596 }
5597
5598 // Is alive closure
5599 G1AlwaysAliveClosure always_alive(_g1h);
5600
5601 // Copying keep alive closure. Applied to referent objects that need
5602 // to be copied.
5603 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5604
5605 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5606
5607 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5608 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5609
5610 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5611 // So this must be true - but assert just in case someone decides to
5612 // change the worker ids.
5613 assert(0 <= worker_id && worker_id < limit, "sanity");
5614 assert(!rp->discovery_is_atomic(), "check this code");
5615
5616 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5617 for (uint idx = worker_id; idx < limit; idx += stride) {
5618 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5619
5620 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5621 while (iter.has_next()) {
5622 // Since discovery is not atomic for the CM ref processor, we
5623 // can see some null referent objects.
5624 iter.load_ptrs(DEBUG_ONLY(true));
5625 oop ref = iter.obj();
5626
5627 // This will filter nulls.
5628 if (iter.is_referent_alive()) {
5629 iter.make_referent_alive();
5630 }
5631 iter.move_to_next();
5632 }
5633 }
5634
5635 // Drain the queue - which may cause stealing
5636 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5637 drain_queue.do_void();
5638 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5639 assert(pss.refs()->is_empty(), "should be");
5640 }
5641 };
5642
5643 // Weak Reference processing during an evacuation pause (part 1).
5644 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5645 double ref_proc_start = os::elapsedTime();
5646
5647 ReferenceProcessor* rp = _ref_processor_stw;
5648 assert(rp->discovery_enabled(), "should have been enabled");
5649
5650 // Any reference objects, in the collection set, that were 'discovered'
5651 // by the CM ref processor should have already been copied (either by
5652 // applying the external root copy closure to the discovered lists, or
5653 // by following an RSet entry).
5654 //
5655 // But some of the referents, that are in the collection set, that these
5656 // reference objects point to may not have been copied: the STW ref
5657 // processor would have seen that the reference object had already
5658 // been 'discovered' and would have skipped discovering the reference,
5659 // but would not have treated the reference object as a regular oop.
5660 // As a result the copy closure would not have been applied to the
5661 // referent object.
5662 //
5663 // We need to explicitly copy these referent objects - the references
5664 // will be processed at the end of remarking.
5665 //
5666 // We also need to do this copying before we process the reference
5667 // objects discovered by the STW ref processor in case one of these
5668 // referents points to another object which is also referenced by an
5669 // object discovered by the STW ref processor.
5670
5671 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5672 no_of_gc_workers == workers()->active_workers(),
5673 "Need to reset active GC workers");
5674
5675 set_par_threads(no_of_gc_workers);
5676 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5677 no_of_gc_workers,
5678 _task_queues);
5679
5680 if (G1CollectedHeap::use_parallel_gc_threads()) {
5681 workers()->run_task(&keep_cm_referents);
5682 } else {
5683 keep_cm_referents.work(0);
5684 }
5685
5686 set_par_threads(0);
5687
5688 // Closure to test whether a referent is alive.
5689 G1STWIsAliveClosure is_alive(this);
5690
5691 // Even when parallel reference processing is enabled, the processing
5692 // of JNI refs is serial and performed serially by the current thread
5693 // rather than by a worker. The following PSS will be used for processing
5694 // JNI refs.
5695
5696 // Use only a single queue for this PSS.
5697 G1ParScanThreadState pss(this, 0, NULL);
5698
5699 // We do not embed a reference processor in the copying/scanning
5700 // closures while we're actually processing the discovered
5701 // reference objects.
5702 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5703 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5704 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5705
5706 pss.set_evac_closure(&scan_evac_cl);
5707 pss.set_evac_failure_closure(&evac_failure_cl);
5708 pss.set_partial_scan_closure(&partial_scan_cl);
5709
5710 assert(pss.refs()->is_empty(), "pre-condition");
5711
5712 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5713 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5714
5715 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5716 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5717
5718 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5719 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5720
5721 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5722 // We also need to mark copied objects.
5723 copy_non_heap_cl = ©_mark_non_heap_cl;
5724 copy_metadata_cl = ©_mark_metadata_cl;
5725 }
5726
5727 // Keep alive closure.
5728 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5729
5730 // Serial Complete GC closure
5731 G1STWDrainQueueClosure drain_queue(this, &pss);
5732
5733 // Setup the soft refs policy...
5734 rp->setup_policy(false);
5735
5736 ReferenceProcessorStats stats;
5737 if (!rp->processing_is_mt()) {
5738 // Serial reference processing...
5739 stats = rp->process_discovered_references(&is_alive,
5740 &keep_alive,
5741 &drain_queue,
5742 NULL,
5743 _gc_timer_stw);
5744 } else {
5745 // Parallel reference processing
5746 assert(rp->num_q() == no_of_gc_workers, "sanity");
5747 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5748
5749 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5750 stats = rp->process_discovered_references(&is_alive,
5751 &keep_alive,
5752 &drain_queue,
5753 &par_task_executor,
5754 _gc_timer_stw);
5755 }
5756
5757 _gc_tracer_stw->report_gc_reference_stats(stats);
5758 // We have completed copying any necessary live referent objects
5759 // (that were not copied during the actual pause) so we can
5760 // retire any active alloc buffers
5761 pss.retire_alloc_buffers();
5762 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5763
5764 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5765 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5766 }
5767
5768 // Weak Reference processing during an evacuation pause (part 2).
5769 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5770 double ref_enq_start = os::elapsedTime();
5771
5772 ReferenceProcessor* rp = _ref_processor_stw;
5773 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5774
5775 // Now enqueue any remaining on the discovered lists on to
5776 // the pending list.
5777 if (!rp->processing_is_mt()) {
5778 // Serial reference processing...
5779 rp->enqueue_discovered_references();
5780 } else {
5781 // Parallel reference enqueueing
5782
5783 assert(no_of_gc_workers == workers()->active_workers(),
5784 "Need to reset active workers");
5785 assert(rp->num_q() == no_of_gc_workers, "sanity");
5786 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5787
5788 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5789 rp->enqueue_discovered_references(&par_task_executor);
5790 }
5791
5792 rp->verify_no_references_recorded();
5793 assert(!rp->discovery_enabled(), "should have been disabled");
5794
5795 // FIXME
5796 // CM's reference processing also cleans up the string and symbol tables.
5797 // Should we do that here also? We could, but it is a serial operation
5798 // and could significantly increase the pause time.
5799
5800 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5801 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5802 }
5803
5804 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5805 _expand_heap_after_alloc_failure = true;
5806 _evacuation_failed = false;
5807
5808 // Should G1EvacuationFailureALot be in effect for this GC?
5809 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5810
5811 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5812
5813 // Disable the hot card cache.
5814 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5815 hot_card_cache->reset_hot_cache_claimed_index();
5816 hot_card_cache->set_use_cache(false);
5817
5818 uint n_workers;
5819 if (G1CollectedHeap::use_parallel_gc_threads()) {
5820 n_workers =
5821 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5822 workers()->active_workers(),
5823 Threads::number_of_non_daemon_threads());
5824 assert(UseDynamicNumberOfGCThreads ||
5825 n_workers == workers()->total_workers(),
5826 "If not dynamic should be using all the workers");
5827 workers()->set_active_workers(n_workers);
5828 set_par_threads(n_workers);
5829 } else {
5830 assert(n_par_threads() == 0,
5831 "Should be the original non-parallel value");
5832 n_workers = 1;
5833 }
5834
5835 G1ParTask g1_par_task(this, _task_queues);
5836
5837 init_for_evac_failure(NULL);
5838
5839 rem_set()->prepare_for_younger_refs_iterate(true);
5840
5841 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5842 double start_par_time_sec = os::elapsedTime();
5843 double end_par_time_sec;
5844
5845 {
5846 StrongRootsScope srs(this);
5847
5848 if (G1CollectedHeap::use_parallel_gc_threads()) {
5849 // The individual threads will set their evac-failure closures.
5850 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5851 // These tasks use ShareHeap::_process_strong_tasks
5852 assert(UseDynamicNumberOfGCThreads ||
5853 workers()->active_workers() == workers()->total_workers(),
5854 "If not dynamic should be using all the workers");
5855 workers()->run_task(&g1_par_task);
5856 } else {
5857 g1_par_task.set_for_termination(n_workers);
5858 g1_par_task.work(0);
5859 }
5860 end_par_time_sec = os::elapsedTime();
5861
5862 // Closing the inner scope will execute the destructor
5863 // for the StrongRootsScope object. We record the current
5864 // elapsed time before closing the scope so that time
5865 // taken for the SRS destructor is NOT included in the
5866 // reported parallel time.
5867 }
5868
5869 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5870 g1_policy()->phase_times()->record_par_time(par_time_ms);
5871
5872 double code_root_fixup_time_ms =
5873 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5874 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5875
5876 set_par_threads(0);
5877
5878 // Process any discovered reference objects - we have
5879 // to do this _before_ we retire the GC alloc regions
5880 // as we may have to copy some 'reachable' referent
5881 // objects (and their reachable sub-graphs) that were
5882 // not copied during the pause.
5883 process_discovered_references(n_workers);
5884
5885 // Weak root processing.
5886 {
5887 G1STWIsAliveClosure is_alive(this);
5888 G1KeepAliveClosure keep_alive(this);
5889 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5890 }
5891
5892 release_gc_alloc_regions(n_workers, evacuation_info);
5893 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5894
5895 // Reset and re-enable the hot card cache.
5896 // Note the counts for the cards in the regions in the
5897 // collection set are reset when the collection set is freed.
5898 hot_card_cache->reset_hot_cache();
5899 hot_card_cache->set_use_cache(true);
5900
5901 // Migrate the strong code roots attached to each region in
5902 // the collection set. Ideally we would like to do this
5903 // after we have finished the scanning/evacuation of the
5904 // strong code roots for a particular heap region.
5905 migrate_strong_code_roots();
5906
5907 if (g1_policy()->during_initial_mark_pause()) {
5908 // Reset the claim values set during marking the strong code roots
5909 reset_heap_region_claim_values();
5910 }
5911
5912 finalize_for_evac_failure();
5913
5914 if (evacuation_failed()) {
5915 remove_self_forwarding_pointers();
5916
5917 // Reset the G1EvacuationFailureALot counters and flags
5918 // Note: the values are reset only when an actual
5919 // evacuation failure occurs.
5920 NOT_PRODUCT(reset_evacuation_should_fail();)
5921 }
5922
5923 // Enqueue any remaining references remaining on the STW
5924 // reference processor's discovered lists. We need to do
5925 // this after the card table is cleaned (and verified) as
5926 // the act of enqueueing entries on to the pending list
5927 // will log these updates (and dirty their associated
5928 // cards). We need these updates logged to update any
5929 // RSets.
5930 enqueue_discovered_references(n_workers);
5931
5932 if (G1DeferredRSUpdate) {
5933 RedirtyLoggedCardTableEntryFastClosure redirty;
5934 dirty_card_queue_set().set_closure(&redirty);
5935 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5936
5937 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5938 dcq.merge_bufferlists(&dirty_card_queue_set());
5939 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5940 }
5941 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5942 }
5943
5944 void G1CollectedHeap::free_region(HeapRegion* hr,
5945 FreeRegionList* free_list,
5946 bool par) {
5947 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5948 assert(!hr->is_empty(), "the region should not be empty");
5949 assert(free_list != NULL, "pre-condition");
5950
5951 // Clear the card counts for this region.
5952 // Note: we only need to do this if the region is not young
5953 // (since we don't refine cards in young regions).
5954 if (!hr->is_young()) {
5955 _cg1r->hot_card_cache()->reset_card_counts(hr);
5956 }
5957 hr->hr_clear(par, true /* clear_space */);
5958 free_list->add_as_head(hr);
5959 }
5960
5961 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5962 FreeRegionList* free_list,
5963 bool par) {
5964 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5965 assert(free_list != NULL, "pre-condition");
5966
5967 size_t hr_capacity = hr->capacity();
5968 // We need to read this before we make the region non-humongous,
5969 // otherwise the information will be gone.
5970 uint last_index = hr->last_hc_index();
5971 hr->set_notHumongous();
5972 free_region(hr, free_list, par);
5973
5974 uint i = hr->hrs_index() + 1;
5975 while (i < last_index) {
5976 HeapRegion* curr_hr = region_at(i);
5977 assert(curr_hr->continuesHumongous(), "invariant");
5978 curr_hr->set_notHumongous();
5979 free_region(curr_hr, free_list, par);
5980 i += 1;
5981 }
5982 }
5983
5984 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5985 const HeapRegionSetCount& humongous_regions_removed) {
5986 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5987 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5988 _old_set.bulk_remove(old_regions_removed);
5989 _humongous_set.bulk_remove(humongous_regions_removed);
5990 }
5991
5992 }
5993
5994 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5995 assert(list != NULL, "list can't be null");
5996 if (!list->is_empty()) {
5997 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5998 _free_list.add_as_head(list);
5999 }
6000 }
6001
6002 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6003 assert(_summary_bytes_used >= bytes,
6004 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6005 _summary_bytes_used, bytes));
6006 _summary_bytes_used -= bytes;
6007 }
6008
6009 class G1ParCleanupCTTask : public AbstractGangTask {
6010 G1SATBCardTableModRefBS* _ct_bs;
6011 G1CollectedHeap* _g1h;
6012 HeapRegion* volatile _su_head;
6013 public:
6014 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6015 G1CollectedHeap* g1h) :
6016 AbstractGangTask("G1 Par Cleanup CT Task"),
6017 _ct_bs(ct_bs), _g1h(g1h) { }
6018
6019 void work(uint worker_id) {
6020 HeapRegion* r;
6021 while (r = _g1h->pop_dirty_cards_region()) {
6022 clear_cards(r);
6023 }
6024 }
6025
6026 void clear_cards(HeapRegion* r) {
6027 // Cards of the survivors should have already been dirtied.
6028 if (!r->is_survivor()) {
6029 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6030 }
6031 }
6032 };
6033
6034 #ifndef PRODUCT
6035 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6036 G1CollectedHeap* _g1h;
6037 G1SATBCardTableModRefBS* _ct_bs;
6038 public:
6039 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6040 : _g1h(g1h), _ct_bs(ct_bs) { }
6041 virtual bool doHeapRegion(HeapRegion* r) {
6042 if (r->is_survivor()) {
6043 _g1h->verify_dirty_region(r);
6044 } else {
6045 _g1h->verify_not_dirty_region(r);
6046 }
6047 return false;
6048 }
6049 };
6050
6051 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6052 // All of the region should be clean.
6053 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6054 MemRegion mr(hr->bottom(), hr->end());
6055 ct_bs->verify_not_dirty_region(mr);
6056 }
6057
6058 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6059 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6060 // dirty allocated blocks as they allocate them. The thread that
6061 // retires each region and replaces it with a new one will do a
6062 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6063 // not dirty that area (one less thing to have to do while holding
6064 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6065 // is dirty.
6066 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6067 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6068 if (hr->is_young()) {
6069 ct_bs->verify_g1_young_region(mr);
6070 } else {
6071 ct_bs->verify_dirty_region(mr);
6072 }
6073 }
6074
6075 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6076 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6077 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6078 verify_dirty_region(hr);
6079 }
6080 }
6081
6082 void G1CollectedHeap::verify_dirty_young_regions() {
6083 verify_dirty_young_list(_young_list->first_region());
6084 }
6085 #endif
6086
6087 void G1CollectedHeap::cleanUpCardTable() {
6088 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6089 double start = os::elapsedTime();
6090
6091 {
6092 // Iterate over the dirty cards region list.
6093 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6094
6095 if (G1CollectedHeap::use_parallel_gc_threads()) {
6096 set_par_threads();
6097 workers()->run_task(&cleanup_task);
6098 set_par_threads(0);
6099 } else {
6100 while (_dirty_cards_region_list) {
6101 HeapRegion* r = _dirty_cards_region_list;
6102 cleanup_task.clear_cards(r);
6103 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6104 if (_dirty_cards_region_list == r) {
6105 // The last region.
6106 _dirty_cards_region_list = NULL;
6107 }
6108 r->set_next_dirty_cards_region(NULL);
6109 }
6110 }
6111 #ifndef PRODUCT
6112 if (G1VerifyCTCleanup || VerifyAfterGC) {
6113 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6114 heap_region_iterate(&cleanup_verifier);
6115 }
6116 #endif
6117 }
6118
6119 double elapsed = os::elapsedTime() - start;
6120 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6121 }
6122
6123 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6124 size_t pre_used = 0;
6125 FreeRegionList local_free_list("Local List for CSet Freeing");
6126
6127 double young_time_ms = 0.0;
6128 double non_young_time_ms = 0.0;
6129
6130 // Since the collection set is a superset of the the young list,
6131 // all we need to do to clear the young list is clear its
6132 // head and length, and unlink any young regions in the code below
6133 _young_list->clear();
6134
6135 G1CollectorPolicy* policy = g1_policy();
6136
6137 double start_sec = os::elapsedTime();
6138 bool non_young = true;
6139
6140 HeapRegion* cur = cs_head;
6141 int age_bound = -1;
6142 size_t rs_lengths = 0;
6143
6144 while (cur != NULL) {
6145 assert(!is_on_master_free_list(cur), "sanity");
6146 if (non_young) {
6147 if (cur->is_young()) {
6148 double end_sec = os::elapsedTime();
6149 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6150 non_young_time_ms += elapsed_ms;
6151
6152 start_sec = os::elapsedTime();
6153 non_young = false;
6154 }
6155 } else {
6156 if (!cur->is_young()) {
6157 double end_sec = os::elapsedTime();
6158 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6159 young_time_ms += elapsed_ms;
6160
6161 start_sec = os::elapsedTime();
6162 non_young = true;
6163 }
6164 }
6165
6166 rs_lengths += cur->rem_set()->occupied();
6167
6168 HeapRegion* next = cur->next_in_collection_set();
6169 assert(cur->in_collection_set(), "bad CS");
6170 cur->set_next_in_collection_set(NULL);
6171 cur->set_in_collection_set(false);
6172
6173 if (cur->is_young()) {
6174 int index = cur->young_index_in_cset();
6175 assert(index != -1, "invariant");
6176 assert((uint) index < policy->young_cset_region_length(), "invariant");
6177 size_t words_survived = _surviving_young_words[index];
6178 cur->record_surv_words_in_group(words_survived);
6179
6180 // At this point the we have 'popped' cur from the collection set
6181 // (linked via next_in_collection_set()) but it is still in the
6182 // young list (linked via next_young_region()). Clear the
6183 // _next_young_region field.
6184 cur->set_next_young_region(NULL);
6185 } else {
6186 int index = cur->young_index_in_cset();
6187 assert(index == -1, "invariant");
6188 }
6189
6190 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6191 (!cur->is_young() && cur->young_index_in_cset() == -1),
6192 "invariant" );
6193
6194 if (!cur->evacuation_failed()) {
6195 MemRegion used_mr = cur->used_region();
6196
6197 // And the region is empty.
6198 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6199 pre_used += cur->used();
6200 free_region(cur, &local_free_list, false /* par */);
6201 } else {
6202 cur->uninstall_surv_rate_group();
6203 if (cur->is_young()) {
6204 cur->set_young_index_in_cset(-1);
6205 }
6206 cur->set_not_young();
6207 cur->set_evacuation_failed(false);
6208 // The region is now considered to be old.
6209 _old_set.add(cur);
6210 evacuation_info.increment_collectionset_used_after(cur->used());
6211 }
6212 cur = next;
6213 }
6214
6215 evacuation_info.set_regions_freed(local_free_list.length());
6216 policy->record_max_rs_lengths(rs_lengths);
6217 policy->cset_regions_freed();
6218
6219 double end_sec = os::elapsedTime();
6220 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6221
6222 if (non_young) {
6223 non_young_time_ms += elapsed_ms;
6224 } else {
6225 young_time_ms += elapsed_ms;
6226 }
6227
6228 prepend_to_freelist(&local_free_list);
6229 decrement_summary_bytes(pre_used);
6230 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6231 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6232 }
6233
6234 // This routine is similar to the above but does not record
6235 // any policy statistics or update free lists; we are abandoning
6236 // the current incremental collection set in preparation of a
6237 // full collection. After the full GC we will start to build up
6238 // the incremental collection set again.
6239 // This is only called when we're doing a full collection
6240 // and is immediately followed by the tearing down of the young list.
6241
6242 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6243 HeapRegion* cur = cs_head;
6244
6245 while (cur != NULL) {
6246 HeapRegion* next = cur->next_in_collection_set();
6247 assert(cur->in_collection_set(), "bad CS");
6248 cur->set_next_in_collection_set(NULL);
6249 cur->set_in_collection_set(false);
6250 cur->set_young_index_in_cset(-1);
6251 cur = next;
6252 }
6253 }
6254
6255 void G1CollectedHeap::set_free_regions_coming() {
6256 if (G1ConcRegionFreeingVerbose) {
6257 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6258 "setting free regions coming");
6259 }
6260
6261 assert(!free_regions_coming(), "pre-condition");
6262 _free_regions_coming = true;
6263 }
6264
6265 void G1CollectedHeap::reset_free_regions_coming() {
6266 assert(free_regions_coming(), "pre-condition");
6267
6268 {
6269 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6270 _free_regions_coming = false;
6271 SecondaryFreeList_lock->notify_all();
6272 }
6273
6274 if (G1ConcRegionFreeingVerbose) {
6275 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6276 "reset free regions coming");
6277 }
6278 }
6279
6280 void G1CollectedHeap::wait_while_free_regions_coming() {
6281 // Most of the time we won't have to wait, so let's do a quick test
6282 // first before we take the lock.
6283 if (!free_regions_coming()) {
6284 return;
6285 }
6286
6287 if (G1ConcRegionFreeingVerbose) {
6288 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6289 "waiting for free regions");
6290 }
6291
6292 {
6293 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6294 while (free_regions_coming()) {
6295 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6296 }
6297 }
6298
6299 if (G1ConcRegionFreeingVerbose) {
6300 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6301 "done waiting for free regions");
6302 }
6303 }
6304
6305 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6306 assert(heap_lock_held_for_gc(),
6307 "the heap lock should already be held by or for this thread");
6308 _young_list->push_region(hr);
6309 }
6310
6311 class NoYoungRegionsClosure: public HeapRegionClosure {
6312 private:
6313 bool _success;
6314 public:
6315 NoYoungRegionsClosure() : _success(true) { }
6316 bool doHeapRegion(HeapRegion* r) {
6317 if (r->is_young()) {
6318 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6319 r->bottom(), r->end());
6320 _success = false;
6321 }
6322 return false;
6323 }
6324 bool success() { return _success; }
6325 };
6326
6327 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6328 bool ret = _young_list->check_list_empty(check_sample);
6329
6330 if (check_heap) {
6331 NoYoungRegionsClosure closure;
6332 heap_region_iterate(&closure);
6333 ret = ret && closure.success();
6334 }
6335
6336 return ret;
6337 }
6338
6339 class TearDownRegionSetsClosure : public HeapRegionClosure {
6340 private:
6341 HeapRegionSet *_old_set;
6342
6343 public:
6344 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6345
6346 bool doHeapRegion(HeapRegion* r) {
6347 if (r->is_empty()) {
6348 // We ignore empty regions, we'll empty the free list afterwards
6349 } else if (r->is_young()) {
6350 // We ignore young regions, we'll empty the young list afterwards
6351 } else if (r->isHumongous()) {
6352 // We ignore humongous regions, we're not tearing down the
6353 // humongous region set
6354 } else {
6355 // The rest should be old
6356 _old_set->remove(r);
6357 }
6358 return false;
6359 }
6360
6361 ~TearDownRegionSetsClosure() {
6362 assert(_old_set->is_empty(), "post-condition");
6363 }
6364 };
6365
6366 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6367 assert_at_safepoint(true /* should_be_vm_thread */);
6368
6369 if (!free_list_only) {
6370 TearDownRegionSetsClosure cl(&_old_set);
6371 heap_region_iterate(&cl);
6372
6373 // Need to do this after the heap iteration to be able to
6374 // recognize the young regions and ignore them during the iteration.
6375 _young_list->empty_list();
6376 }
6377 _free_list.remove_all();
6378 }
6379
6380 class RebuildRegionSetsClosure : public HeapRegionClosure {
6381 private:
6382 bool _free_list_only;
6383 HeapRegionSet* _old_set;
6384 FreeRegionList* _free_list;
6385 size_t _total_used;
6386
6387 public:
6388 RebuildRegionSetsClosure(bool free_list_only,
6389 HeapRegionSet* old_set, FreeRegionList* free_list) :
6390 _free_list_only(free_list_only),
6391 _old_set(old_set), _free_list(free_list), _total_used(0) {
6392 assert(_free_list->is_empty(), "pre-condition");
6393 if (!free_list_only) {
6394 assert(_old_set->is_empty(), "pre-condition");
6395 }
6396 }
6397
6398 bool doHeapRegion(HeapRegion* r) {
6399 if (r->continuesHumongous()) {
6400 return false;
6401 }
6402
6403 if (r->is_empty()) {
6404 // Add free regions to the free list
6405 _free_list->add_as_tail(r);
6406 } else if (!_free_list_only) {
6407 assert(!r->is_young(), "we should not come across young regions");
6408
6409 if (r->isHumongous()) {
6410 // We ignore humongous regions, we left the humongous set unchanged
6411 } else {
6412 // The rest should be old, add them to the old set
6413 _old_set->add(r);
6414 }
6415 _total_used += r->used();
6416 }
6417
6418 return false;
6419 }
6420
6421 size_t total_used() {
6422 return _total_used;
6423 }
6424 };
6425
6426 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6427 assert_at_safepoint(true /* should_be_vm_thread */);
6428
6429 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6430 heap_region_iterate(&cl);
6431
6432 if (!free_list_only) {
6433 _summary_bytes_used = cl.total_used();
6434 }
6435 assert(_summary_bytes_used == recalculate_used(),
6436 err_msg("inconsistent _summary_bytes_used, "
6437 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6438 _summary_bytes_used, recalculate_used()));
6439 }
6440
6441 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6442 _refine_cte_cl->set_concurrent(concurrent);
6443 }
6444
6445 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6446 HeapRegion* hr = heap_region_containing(p);
6447 if (hr == NULL) {
6448 return false;
6449 } else {
6450 return hr->is_in(p);
6451 }
6452 }
6453
6454 // Methods for the mutator alloc region
6455
6456 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6457 bool force) {
6458 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6459 assert(!force || g1_policy()->can_expand_young_list(),
6460 "if force is true we should be able to expand the young list");
6461 bool young_list_full = g1_policy()->is_young_list_full();
6462 if (force || !young_list_full) {
6463 HeapRegion* new_alloc_region = new_region(word_size,
6464 false /* do_expand */);
6465 if (new_alloc_region != NULL) {
6466 set_region_short_lived_locked(new_alloc_region);
6467 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6468 return new_alloc_region;
6469 }
6470 }
6471 return NULL;
6472 }
6473
6474 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6475 size_t allocated_bytes) {
6476 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6477 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6478
6479 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6480 _summary_bytes_used += allocated_bytes;
6481 _hr_printer.retire(alloc_region);
6482 // We update the eden sizes here, when the region is retired,
6483 // instead of when it's allocated, since this is the point that its
6484 // used space has been recored in _summary_bytes_used.
6485 g1mm()->update_eden_size();
6486 }
6487
6488 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6489 bool force) {
6490 return _g1h->new_mutator_alloc_region(word_size, force);
6491 }
6492
6493 void G1CollectedHeap::set_par_threads() {
6494 // Don't change the number of workers. Use the value previously set
6495 // in the workgroup.
6496 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6497 uint n_workers = workers()->active_workers();
6498 assert(UseDynamicNumberOfGCThreads ||
6499 n_workers == workers()->total_workers(),
6500 "Otherwise should be using the total number of workers");
6501 if (n_workers == 0) {
6502 assert(false, "Should have been set in prior evacuation pause.");
6503 n_workers = ParallelGCThreads;
6504 workers()->set_active_workers(n_workers);
6505 }
6506 set_par_threads(n_workers);
6507 }
6508
6509 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6510 size_t allocated_bytes) {
6511 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6512 }
6513
6514 // Methods for the GC alloc regions
6515
6516 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6517 uint count,
6518 GCAllocPurpose ap) {
6519 assert(FreeList_lock->owned_by_self(), "pre-condition");
6520
6521 if (count < g1_policy()->max_regions(ap)) {
6522 HeapRegion* new_alloc_region = new_region(word_size,
6523 true /* do_expand */);
6524 if (new_alloc_region != NULL) {
6525 // We really only need to do this for old regions given that we
6526 // should never scan survivors. But it doesn't hurt to do it
6527 // for survivors too.
6528 new_alloc_region->set_saved_mark();
6529 if (ap == GCAllocForSurvived) {
6530 new_alloc_region->set_survivor();
6531 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6532 } else {
6533 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6534 }
6535 bool during_im = g1_policy()->during_initial_mark_pause();
6536 new_alloc_region->note_start_of_copying(during_im);
6537 return new_alloc_region;
6538 } else {
6539 g1_policy()->note_alloc_region_limit_reached(ap);
6540 }
6541 }
6542 return NULL;
6543 }
6544
6545 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6546 size_t allocated_bytes,
6547 GCAllocPurpose ap) {
6548 bool during_im = g1_policy()->during_initial_mark_pause();
6549 alloc_region->note_end_of_copying(during_im);
6550 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6551 if (ap == GCAllocForSurvived) {
6552 young_list()->add_survivor_region(alloc_region);
6553 } else {
6554 _old_set.add(alloc_region);
6555 }
6556 _hr_printer.retire(alloc_region);
6557 }
6558
6559 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6560 bool force) {
6561 assert(!force, "not supported for GC alloc regions");
6562 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6563 }
6564
6565 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6566 size_t allocated_bytes) {
6567 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6568 GCAllocForSurvived);
6569 }
6570
6571 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6572 bool force) {
6573 assert(!force, "not supported for GC alloc regions");
6574 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6575 }
6576
6577 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6578 size_t allocated_bytes) {
6579 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6580 GCAllocForTenured);
6581 }
6582 // Heap region set verification
6583
6584 class VerifyRegionListsClosure : public HeapRegionClosure {
6585 private:
6586 HeapRegionSet* _old_set;
6587 HeapRegionSet* _humongous_set;
6588 FreeRegionList* _free_list;
6589
6590 public:
6591 HeapRegionSetCount _old_count;
6592 HeapRegionSetCount _humongous_count;
6593 HeapRegionSetCount _free_count;
6594
6595 VerifyRegionListsClosure(HeapRegionSet* old_set,
6596 HeapRegionSet* humongous_set,
6597 FreeRegionList* free_list) :
6598 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6599 _old_count(), _humongous_count(), _free_count(){ }
6600
6601 bool doHeapRegion(HeapRegion* hr) {
6602 if (hr->continuesHumongous()) {
6603 return false;
6604 }
6605
6606 if (hr->is_young()) {
6607 // TODO
6608 } else if (hr->startsHumongous()) {
6609 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num()));
6610 _humongous_count.increment(1u, hr->capacity());
6611 } else if (hr->is_empty()) {
6612 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num()));
6613 _free_count.increment(1u, hr->capacity());
6614 } else {
6615 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num()));
6616 _old_count.increment(1u, hr->capacity());
6617 }
6618 return false;
6619 }
6620
6621 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6622 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6623 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6624 old_set->total_capacity_bytes(), _old_count.capacity()));
6625
6626 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6627 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6628 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6629
6630 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6631 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6632 free_list->total_capacity_bytes(), _free_count.capacity()));
6633 }
6634 };
6635
6636 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6637 HeapWord* bottom) {
6638 HeapWord* end = bottom + HeapRegion::GrainWords;
6639 MemRegion mr(bottom, end);
6640 assert(_g1_reserved.contains(mr), "invariant");
6641 // This might return NULL if the allocation fails
6642 return new HeapRegion(hrs_index, _bot_shared, mr);
6643 }
6644
6645 void G1CollectedHeap::verify_region_sets() {
6646 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6647
6648 // First, check the explicit lists.
6649 _free_list.verify_list();
6650 {
6651 // Given that a concurrent operation might be adding regions to
6652 // the secondary free list we have to take the lock before
6653 // verifying it.
6654 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6655 _secondary_free_list.verify_list();
6656 }
6657
6658 // If a concurrent region freeing operation is in progress it will
6659 // be difficult to correctly attributed any free regions we come
6660 // across to the correct free list given that they might belong to
6661 // one of several (free_list, secondary_free_list, any local lists,
6662 // etc.). So, if that's the case we will skip the rest of the
6663 // verification operation. Alternatively, waiting for the concurrent
6664 // operation to complete will have a non-trivial effect on the GC's
6665 // operation (no concurrent operation will last longer than the
6666 // interval between two calls to verification) and it might hide
6667 // any issues that we would like to catch during testing.
6668 if (free_regions_coming()) {
6669 return;
6670 }
6671
6672 // Make sure we append the secondary_free_list on the free_list so
6673 // that all free regions we will come across can be safely
6674 // attributed to the free_list.
6675 append_secondary_free_list_if_not_empty_with_lock();
6676
6677 // Finally, make sure that the region accounting in the lists is
6678 // consistent with what we see in the heap.
6679
6680 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6681 heap_region_iterate(&cl);
6682 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6683 }
6684
6685 // Optimized nmethod scanning
6686
6687 class RegisterNMethodOopClosure: public OopClosure {
6688 G1CollectedHeap* _g1h;
6689 nmethod* _nm;
6690
6691 template <class T> void do_oop_work(T* p) {
6692 T heap_oop = oopDesc::load_heap_oop(p);
6693 if (!oopDesc::is_null(heap_oop)) {
6694 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6695 HeapRegion* hr = _g1h->heap_region_containing(obj);
6696 assert(!hr->continuesHumongous(),
6697 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6698 " starting at "HR_FORMAT,
6699 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6700
6701 // HeapRegion::add_strong_code_root() avoids adding duplicate
6702 // entries but having duplicates is OK since we "mark" nmethods
6703 // as visited when we scan the strong code root lists during the GC.
6704 hr->add_strong_code_root(_nm);
6705 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6706 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6707 _nm, HR_FORMAT_PARAMS(hr)));
6708 }
6709 }
6710
6711 public:
6712 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6713 _g1h(g1h), _nm(nm) {}
6714
6715 void do_oop(oop* p) { do_oop_work(p); }
6716 void do_oop(narrowOop* p) { do_oop_work(p); }
6717 };
6718
6719 class UnregisterNMethodOopClosure: public OopClosure {
6720 G1CollectedHeap* _g1h;
6721 nmethod* _nm;
6722
6723 template <class T> void do_oop_work(T* p) {
6724 T heap_oop = oopDesc::load_heap_oop(p);
6725 if (!oopDesc::is_null(heap_oop)) {
6726 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6727 HeapRegion* hr = _g1h->heap_region_containing(obj);
6728 assert(!hr->continuesHumongous(),
6729 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6730 " starting at "HR_FORMAT,
6731 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6732
6733 hr->remove_strong_code_root(_nm);
6734 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6735 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6736 _nm, HR_FORMAT_PARAMS(hr)));
6737 }
6738 }
6739
6740 public:
6741 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6742 _g1h(g1h), _nm(nm) {}
6743
6744 void do_oop(oop* p) { do_oop_work(p); }
6745 void do_oop(narrowOop* p) { do_oop_work(p); }
6746 };
6747
6748 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6749 CollectedHeap::register_nmethod(nm);
6750
6751 guarantee(nm != NULL, "sanity");
6752 RegisterNMethodOopClosure reg_cl(this, nm);
6753 nm->oops_do(®_cl);
6754 }
6755
6756 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6757 CollectedHeap::unregister_nmethod(nm);
6758
6759 guarantee(nm != NULL, "sanity");
6760 UnregisterNMethodOopClosure reg_cl(this, nm);
6761 nm->oops_do(®_cl, true);
6762 }
6763
6764 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6765 public:
6766 bool doHeapRegion(HeapRegion *hr) {
6767 assert(!hr->isHumongous(),
6768 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6769 HR_FORMAT_PARAMS(hr)));
6770 hr->migrate_strong_code_roots();
6771 return false;
6772 }
6773 };
6774
6775 void G1CollectedHeap::migrate_strong_code_roots() {
6776 MigrateCodeRootsHeapRegionClosure cl;
6777 double migrate_start = os::elapsedTime();
6778 collection_set_iterate(&cl);
6779 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6780 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6781 }
6782
6783 // Mark all the code roots that point into regions *not* in the
6784 // collection set.
6785 //
6786 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6787 // walking the the code roots lists of regions not in the collection
6788 // set. Suppose we have an nmethod (M) that points to objects in two
6789 // separate regions - one in the collection set (R1) and one not (R2).
6790 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6791 // nmethod M when walking the code roots for R1. When we come to scan
6792 // the code roots for R2, we would see that M is already marked and it
6793 // would be skipped and the objects in R2 that are referenced from M
6794 // would not be evacuated.
6795
6796 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6797
6798 class MarkStrongCodeRootOopClosure: public OopClosure {
6799 ConcurrentMark* _cm;
6800 HeapRegion* _hr;
6801 uint _worker_id;
6802
6803 template <class T> void do_oop_work(T* p) {
6804 T heap_oop = oopDesc::load_heap_oop(p);
6805 if (!oopDesc::is_null(heap_oop)) {
6806 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6807 // Only mark objects in the region (which is assumed
6808 // to be not in the collection set).
6809 if (_hr->is_in(obj)) {
6810 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6811 }
6812 }
6813 }
6814
6815 public:
6816 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6817 _cm(cm), _hr(hr), _worker_id(worker_id) {
6818 assert(!_hr->in_collection_set(), "sanity");
6819 }
6820
6821 void do_oop(narrowOop* p) { do_oop_work(p); }
6822 void do_oop(oop* p) { do_oop_work(p); }
6823 };
6824
6825 MarkStrongCodeRootOopClosure _oop_cl;
6826
6827 public:
6828 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6829 _oop_cl(cm, hr, worker_id) {}
6830
6831 void do_code_blob(CodeBlob* cb) {
6832 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6833 if (nm != NULL) {
6834 nm->oops_do(&_oop_cl);
6835 }
6836 }
6837 };
6838
6839 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6840 G1CollectedHeap* _g1h;
6841 uint _worker_id;
6842
6843 public:
6844 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6845 _g1h(g1h), _worker_id(worker_id) {}
6846
6847 bool doHeapRegion(HeapRegion *hr) {
6848 HeapRegionRemSet* hrrs = hr->rem_set();
6849 if (hr->continuesHumongous()) {
6850 // Code roots should never be attached to a continuation of a humongous region
6851 assert(hrrs->strong_code_roots_list_length() == 0,
6852 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6853 " starting at "HR_FORMAT", but has "INT32_FORMAT,
6854 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6855 hrrs->strong_code_roots_list_length()));
6856 return false;
6857 }
6858
6859 if (hr->in_collection_set()) {
6860 // Don't mark code roots into regions in the collection set here.
6861 // They will be marked when we scan them.
6862 return false;
6863 }
6864
6865 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6866 hr->strong_code_roots_do(&cb_cl);
6867 return false;
6868 }
6869 };
6870
6871 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6872 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6873 if (G1CollectedHeap::use_parallel_gc_threads()) {
6874 heap_region_par_iterate_chunked(&cl,
6875 worker_id,
6876 workers()->active_workers(),
6877 HeapRegion::ParMarkRootClaimValue);
6878 } else {
6879 heap_region_iterate(&cl);
6880 }
6881 }
6882
6883 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6884 G1CollectedHeap* _g1h;
6885
6886 public:
6887 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6888 _g1h(g1h) {}
6889
6890 void do_code_blob(CodeBlob* cb) {
6891 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6892 if (nm == NULL) {
6893 return;
6894 }
6895
6896 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6897 _g1h->register_nmethod(nm);
6898 }
6899 }
6900 };
6901
6902 void G1CollectedHeap::rebuild_strong_code_roots() {
6903 RebuildStrongCodeRootClosure blob_cl(this);
6904 CodeCache::blobs_do(&blob_cl);
6905 }