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