1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/codeCache.hpp"
27 #include "code/icBuffer.hpp"
28 #include "gc_implementation/g1/bufferingOopClosure.hpp"
29 #include "gc_implementation/g1/concurrentG1Refine.hpp"
30 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
31 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
32 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
33 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
34 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
35 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
36 #include "gc_implementation/g1/g1EvacFailure.hpp"
37 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
38 #include "gc_implementation/g1/g1Log.hpp"
39 #include "gc_implementation/g1/g1MarkSweep.hpp"
40 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
41 #include "gc_implementation/g1/g1RemSet.inline.hpp"
42 #include "gc_implementation/g1/g1YCTypes.hpp"
43 #include "gc_implementation/g1/heapRegion.inline.hpp"
44 #include "gc_implementation/g1/heapRegionRemSet.hpp"
45 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
46 #include "gc_implementation/g1/vm_operations_g1.hpp"
47 #include "gc_implementation/shared/gcHeapSummary.hpp"
48 #include "gc_implementation/shared/gcTimer.hpp"
49 #include "gc_implementation/shared/gcTrace.hpp"
50 #include "gc_implementation/shared/gcTraceTime.hpp"
51 #include "gc_implementation/shared/isGCActiveMark.hpp"
52 #include "memory/gcLocker.inline.hpp"
53 #include "memory/genOopClosures.inline.hpp"
54 #include "memory/generationSpec.hpp"
55 #include "memory/referenceProcessor.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "oops/oop.pcgc.inline.hpp"
58 #include "runtime/aprofiler.hpp"
59 #include "runtime/vmThread.hpp"
60 #include "utilities/ticks.hpp"
61
62 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
63
64 // turn it on so that the contents of the young list (scan-only /
65 // to-be-collected) are printed at "strategic" points before / during
66 // / after the collection --- this is useful for debugging
67 #define YOUNG_LIST_VERBOSE 0
68 // CURRENT STATUS
69 // This file is under construction. Search for "FIXME".
70
71 // INVARIANTS/NOTES
72 //
73 // All allocation activity covered by the G1CollectedHeap interface is
74 // serialized by acquiring the HeapLock. This happens in mem_allocate
75 // and allocate_new_tlab, which are the "entry" points to the
76 // allocation code from the rest of the JVM. (Note that this does not
77 // apply to TLAB allocation, which is not part of this interface: it
78 // is done by clients of this interface.)
79
80 // Notes on implementation of parallelism in different tasks.
81 //
82 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
83 // The number of GC workers is passed to heap_region_par_iterate_chunked().
84 // It does use run_task() which sets _n_workers in the task.
85 // G1ParTask executes g1_process_strong_roots() ->
86 // SharedHeap::process_strong_roots() which calls eventually to
87 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
88 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
89 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
90 //
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 SuspendibleThreadSet* _sts;
96 G1RemSet* _g1rs;
97 ConcurrentG1Refine* _cg1r;
98 bool _concurrent;
99 public:
100 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
101 G1RemSet* g1rs,
102 ConcurrentG1Refine* cg1r) :
103 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
104 {}
105 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
106 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
107 // This path is executed by the concurrent refine or mutator threads,
108 // concurrently, and so we do not care if card_ptr contains references
109 // that point into the collection set.
110 assert(!oops_into_cset, "should be");
111
112 if (_concurrent && _sts->should_yield()) {
113 // Caller will actually yield.
114 return false;
115 }
116 // Otherwise, we finished successfully; return true.
117 return true;
118 }
119 void set_concurrent(bool b) { _concurrent = b; }
120 };
121
122
123 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
124 int _calls;
125 G1CollectedHeap* _g1h;
126 CardTableModRefBS* _ctbs;
127 int _histo[256];
128 public:
129 ClearLoggedCardTableEntryClosure() :
130 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
131 {
132 for (int i = 0; i < 256; i++) _histo[i] = 0;
133 }
134 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
135 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
136 _calls++;
137 unsigned char* ujb = (unsigned char*)card_ptr;
138 int ind = (int)(*ujb);
139 _histo[ind]++;
140 *card_ptr = -1;
141 }
142 return true;
143 }
144 int calls() { return _calls; }
145 void print_histo() {
146 gclog_or_tty->print_cr("Card table value histogram:");
147 for (int i = 0; i < 256; i++) {
148 if (_histo[i] != 0) {
149 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
150 }
151 }
152 }
153 };
154
155 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
156 int _calls;
157 G1CollectedHeap* _g1h;
158 CardTableModRefBS* _ctbs;
159 public:
160 RedirtyLoggedCardTableEntryClosure() :
161 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
162
163 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
164 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
165 _calls++;
166 *card_ptr = 0;
167 }
168 return true;
169 }
170 int calls() { return _calls; }
171 };
172
173 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
174 public:
175 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
176 *card_ptr = CardTableModRefBS::dirty_card_val();
177 return true;
178 }
179 };
180
181 YoungList::YoungList(G1CollectedHeap* g1h) :
182 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
183 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
184 guarantee(check_list_empty(false), "just making sure...");
185 }
186
187 void YoungList::push_region(HeapRegion *hr) {
188 assert(!hr->is_young(), "should not already be young");
189 assert(hr->get_next_young_region() == NULL, "cause it should!");
190
191 hr->set_next_young_region(_head);
192 _head = hr;
193
194 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
195 ++_length;
196 }
197
198 void YoungList::add_survivor_region(HeapRegion* hr) {
199 assert(hr->is_survivor(), "should be flagged as survivor region");
200 assert(hr->get_next_young_region() == NULL, "cause it should!");
201
202 hr->set_next_young_region(_survivor_head);
203 if (_survivor_head == NULL) {
204 _survivor_tail = hr;
205 }
206 _survivor_head = hr;
207 ++_survivor_length;
208 }
209
210 void YoungList::empty_list(HeapRegion* list) {
211 while (list != NULL) {
212 HeapRegion* next = list->get_next_young_region();
213 list->set_next_young_region(NULL);
214 list->uninstall_surv_rate_group();
215 list->set_not_young();
216 list = next;
217 }
218 }
219
220 void YoungList::empty_list() {
221 assert(check_list_well_formed(), "young list should be well formed");
222
223 empty_list(_head);
224 _head = NULL;
225 _length = 0;
226
227 empty_list(_survivor_head);
228 _survivor_head = NULL;
229 _survivor_tail = NULL;
230 _survivor_length = 0;
231
232 _last_sampled_rs_lengths = 0;
233
234 assert(check_list_empty(false), "just making sure...");
235 }
236
237 bool YoungList::check_list_well_formed() {
238 bool ret = true;
239
240 uint length = 0;
241 HeapRegion* curr = _head;
242 HeapRegion* last = NULL;
243 while (curr != NULL) {
244 if (!curr->is_young()) {
245 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
246 "incorrectly tagged (y: %d, surv: %d)",
247 curr->bottom(), curr->end(),
248 curr->is_young(), curr->is_survivor());
249 ret = false;
250 }
251 ++length;
252 last = curr;
253 curr = curr->get_next_young_region();
254 }
255 ret = ret && (length == _length);
256
257 if (!ret) {
258 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
259 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
260 length, _length);
261 }
262
263 return ret;
264 }
265
266 bool YoungList::check_list_empty(bool check_sample) {
267 bool ret = true;
268
269 if (_length != 0) {
270 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
271 _length);
272 ret = false;
273 }
274 if (check_sample && _last_sampled_rs_lengths != 0) {
275 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
276 ret = false;
277 }
278 if (_head != NULL) {
279 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
280 ret = false;
281 }
282 if (!ret) {
283 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
284 }
285
286 return ret;
287 }
288
289 void
290 YoungList::rs_length_sampling_init() {
291 _sampled_rs_lengths = 0;
292 _curr = _head;
293 }
294
295 bool
296 YoungList::rs_length_sampling_more() {
297 return _curr != NULL;
298 }
299
300 void
301 YoungList::rs_length_sampling_next() {
302 assert( _curr != NULL, "invariant" );
303 size_t rs_length = _curr->rem_set()->occupied();
304
305 _sampled_rs_lengths += rs_length;
306
307 // The current region may not yet have been added to the
308 // incremental collection set (it gets added when it is
309 // retired as the current allocation region).
310 if (_curr->in_collection_set()) {
311 // Update the collection set policy information for this region
312 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
313 }
314
315 _curr = _curr->get_next_young_region();
316 if (_curr == NULL) {
317 _last_sampled_rs_lengths = _sampled_rs_lengths;
318 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
319 }
320 }
321
322 void
323 YoungList::reset_auxilary_lists() {
324 guarantee( is_empty(), "young list should be empty" );
325 assert(check_list_well_formed(), "young list should be well formed");
326
327 // Add survivor regions to SurvRateGroup.
328 _g1h->g1_policy()->note_start_adding_survivor_regions();
329 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
330
331 int young_index_in_cset = 0;
332 for (HeapRegion* curr = _survivor_head;
333 curr != NULL;
334 curr = curr->get_next_young_region()) {
335 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
336
337 // The region is a non-empty survivor so let's add it to
338 // the incremental collection set for the next evacuation
339 // pause.
340 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
341 young_index_in_cset += 1;
342 }
343 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
344 _g1h->g1_policy()->note_stop_adding_survivor_regions();
345
346 _head = _survivor_head;
347 _length = _survivor_length;
348 if (_survivor_head != NULL) {
349 assert(_survivor_tail != NULL, "cause it shouldn't be");
350 assert(_survivor_length > 0, "invariant");
351 _survivor_tail->set_next_young_region(NULL);
352 }
353
354 // Don't clear the survivor list handles until the start of
355 // the next evacuation pause - we need it in order to re-tag
356 // the survivor regions from this evacuation pause as 'young'
357 // at the start of the next.
358
359 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
360
361 assert(check_list_well_formed(), "young list should be well formed");
362 }
363
364 void YoungList::print() {
365 HeapRegion* lists[] = {_head, _survivor_head};
366 const char* names[] = {"YOUNG", "SURVIVOR"};
367
368 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
369 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
370 HeapRegion *curr = lists[list];
371 if (curr == NULL)
372 gclog_or_tty->print_cr(" empty");
373 while (curr != NULL) {
374 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
375 HR_FORMAT_PARAMS(curr),
376 curr->prev_top_at_mark_start(),
377 curr->next_top_at_mark_start(),
378 curr->age_in_surv_rate_group_cond());
379 curr = curr->get_next_young_region();
380 }
381 }
382
383 gclog_or_tty->print_cr("");
384 }
385
386 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
387 {
388 // Claim the right to put the region on the dirty cards region list
389 // by installing a self pointer.
390 HeapRegion* next = hr->get_next_dirty_cards_region();
391 if (next == NULL) {
392 HeapRegion* res = (HeapRegion*)
393 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
394 NULL);
395 if (res == NULL) {
396 HeapRegion* head;
397 do {
398 // Put the region to the dirty cards region list.
399 head = _dirty_cards_region_list;
400 next = (HeapRegion*)
401 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
402 if (next == head) {
403 assert(hr->get_next_dirty_cards_region() == hr,
404 "hr->get_next_dirty_cards_region() != hr");
405 if (next == NULL) {
406 // The last region in the list points to itself.
407 hr->set_next_dirty_cards_region(hr);
408 } else {
409 hr->set_next_dirty_cards_region(next);
410 }
411 }
412 } while (next != head);
413 }
414 }
415 }
416
417 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
418 {
419 HeapRegion* head;
420 HeapRegion* hr;
421 do {
422 head = _dirty_cards_region_list;
423 if (head == NULL) {
424 return NULL;
425 }
426 HeapRegion* new_head = head->get_next_dirty_cards_region();
427 if (head == new_head) {
428 // The last region.
429 new_head = NULL;
430 }
431 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
432 head);
433 } while (hr != head);
434 assert(hr != NULL, "invariant");
435 hr->set_next_dirty_cards_region(NULL);
436 return hr;
437 }
438
439 void G1CollectedHeap::stop_conc_gc_threads() {
440 _cg1r->stop();
441 _cmThread->stop();
442 }
443
444 #ifdef ASSERT
445 // A region is added to the collection set as it is retired
446 // so an address p can point to a region which will be in the
447 // collection set but has not yet been retired. This method
448 // therefore is only accurate during a GC pause after all
449 // regions have been retired. It is used for debugging
450 // to check if an nmethod has references to objects that can
451 // be move during a partial collection. Though it can be
452 // inaccurate, it is sufficient for G1 because the conservative
453 // implementation of is_scavengable() for G1 will indicate that
454 // all nmethods must be scanned during a partial collection.
455 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
456 HeapRegion* hr = heap_region_containing(p);
457 return hr != NULL && hr->in_collection_set();
458 }
459 #endif
460
461 // Returns true if the reference points to an object that
462 // can move in an incremental collection.
463 bool G1CollectedHeap::is_scavengable(const void* p) {
464 G1CollectedHeap* g1h = G1CollectedHeap::heap();
465 G1CollectorPolicy* g1p = g1h->g1_policy();
466 HeapRegion* hr = heap_region_containing(p);
467 if (hr == NULL) {
468 // perm gen (or null)
469 return false;
470 } else {
471 return !hr->isHumongous();
472 }
473 }
474
475 void G1CollectedHeap::check_ct_logs_at_safepoint() {
476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
477 CardTableModRefBS* ct_bs = g1_barrier_set();
478
479 // Count the dirty cards at the start.
480 CountNonCleanMemRegionClosure count1(this);
481 ct_bs->mod_card_iterate(&count1);
482 int orig_count = count1.n();
483
484 // First clear the logged cards.
485 ClearLoggedCardTableEntryClosure clear;
486 dcqs.set_closure(&clear);
487 dcqs.apply_closure_to_all_completed_buffers();
488 dcqs.iterate_closure_all_threads(false);
489 clear.print_histo();
490
491 // Now ensure that there's no dirty cards.
492 CountNonCleanMemRegionClosure count2(this);
493 ct_bs->mod_card_iterate(&count2);
494 if (count2.n() != 0) {
495 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
496 count2.n(), orig_count);
497 }
498 guarantee(count2.n() == 0, "Card table should be clean.");
499
500 RedirtyLoggedCardTableEntryClosure redirty;
501 JavaThread::dirty_card_queue_set().set_closure(&redirty);
502 dcqs.apply_closure_to_all_completed_buffers();
503 dcqs.iterate_closure_all_threads(false);
504 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
505 clear.calls(), orig_count);
506 guarantee(redirty.calls() == clear.calls(),
507 "Or else mechanism is broken.");
508
509 CountNonCleanMemRegionClosure count3(this);
510 ct_bs->mod_card_iterate(&count3);
511 if (count3.n() != orig_count) {
512 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
513 orig_count, count3.n());
514 guarantee(count3.n() >= orig_count, "Should have restored them all.");
515 }
516
517 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
518 }
519
520 // Private class members.
521
522 G1CollectedHeap* G1CollectedHeap::_g1h;
523
524 // Private methods.
525
526 HeapRegion*
527 G1CollectedHeap::new_region_try_secondary_free_list() {
528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
529 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
530 if (!_secondary_free_list.is_empty()) {
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "secondary_free_list has %u entries",
534 _secondary_free_list.length());
535 }
536 // It looks as if there are free regions available on the
537 // secondary_free_list. Let's move them to the free_list and try
538 // again to allocate from it.
539 append_secondary_free_list();
540
541 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
542 "empty we should have moved at least one entry to the free_list");
543 HeapRegion* res = _free_list.remove_head();
544 if (G1ConcRegionFreeingVerbose) {
545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
546 "allocated "HR_FORMAT" from secondary_free_list",
547 HR_FORMAT_PARAMS(res));
548 }
549 return res;
550 }
551
552 // Wait here until we get notified either when (a) there are no
553 // more free regions coming or (b) some regions have been moved on
554 // the secondary_free_list.
555 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
556 }
557
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "could not allocate from secondary_free_list");
561 }
562 return NULL;
563 }
564
565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
566 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
567 "the only time we use this to allocate a humongous region is "
568 "when we are allocating a single humongous region");
569
570 HeapRegion* res;
571 if (G1StressConcRegionFreeing) {
572 if (!_secondary_free_list.is_empty()) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "forced to look at the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list();
578 if (res != NULL) {
579 return res;
580 }
581 }
582 }
583 res = _free_list.remove_head_or_null();
584 if (res == NULL) {
585 if (G1ConcRegionFreeingVerbose) {
586 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
587 "res == NULL, trying the secondary_free_list");
588 }
589 res = new_region_try_secondary_free_list();
590 }
591 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
592 // Currently, only attempts to allocate GC alloc regions set
593 // do_expand to true. So, we should only reach here during a
594 // safepoint. If this assumption changes we might have to
595 // reconsider the use of _expand_heap_after_alloc_failure.
596 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
597
598 ergo_verbose1(ErgoHeapSizing,
599 "attempt heap expansion",
600 ergo_format_reason("region allocation request failed")
601 ergo_format_byte("allocation request"),
602 word_size * HeapWordSize);
603 if (expand(word_size * HeapWordSize)) {
604 // Given that expand() succeeded in expanding the heap, and we
605 // always expand the heap by an amount aligned to the heap
606 // region size, the free list should in theory not be empty. So
607 // it would probably be OK to use remove_head(). But the extra
608 // check for NULL is unlikely to be a performance issue here (we
609 // just expanded the heap!) so let's just be conservative and
610 // use remove_head_or_null().
611 res = _free_list.remove_head_or_null();
612 } else {
613 _expand_heap_after_alloc_failure = false;
614 }
615 }
616 return res;
617 }
618
619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
620 size_t word_size) {
621 assert(isHumongous(word_size), "word_size should be humongous");
622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
623
624 uint first = G1_NULL_HRS_INDEX;
625 if (num_regions == 1) {
626 // Only one region to allocate, no need to go through the slower
627 // path. The caller will attempt the expansion if this fails, so
628 // let's not try to expand here too.
629 HeapRegion* hr = new_region(word_size, false /* do_expand */);
630 if (hr != NULL) {
631 first = hr->hrs_index();
632 } else {
633 first = G1_NULL_HRS_INDEX;
634 }
635 } else {
636 // We can't allocate humongous regions while cleanupComplete() is
637 // running, since some of the regions we find to be empty might not
638 // yet be added to the free list and it is not straightforward to
639 // know which list they are on so that we can remove them. Note
640 // that we only need to do this if we need to allocate more than
641 // one region to satisfy the current humongous allocation
642 // request. If we are only allocating one region we use the common
643 // region allocation code (see above).
644 wait_while_free_regions_coming();
645 append_secondary_free_list_if_not_empty_with_lock();
646
647 if (free_regions() >= num_regions) {
648 first = _hrs.find_contiguous(num_regions);
649 if (first != G1_NULL_HRS_INDEX) {
650 for (uint i = first; i < first + num_regions; ++i) {
651 HeapRegion* hr = region_at(i);
652 assert(hr->is_empty(), "sanity");
653 assert(is_on_master_free_list(hr), "sanity");
654 hr->set_pending_removal(true);
655 }
656 _free_list.remove_all_pending(num_regions);
657 }
658 }
659 }
660 return first;
661 }
662
663 HeapWord*
664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
665 uint num_regions,
666 size_t word_size) {
667 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
668 assert(isHumongous(word_size), "word_size should be humongous");
669 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
670
671 // Index of last region in the series + 1.
672 uint last = first + num_regions;
673
674 // We need to initialize the region(s) we just discovered. This is
675 // a bit tricky given that it can happen concurrently with
676 // refinement threads refining cards on these regions and
677 // potentially wanting to refine the BOT as they are scanning
678 // those cards (this can happen shortly after a cleanup; see CR
679 // 6991377). So we have to set up the region(s) carefully and in
680 // a specific order.
681
682 // The word size sum of all the regions we will allocate.
683 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
684 assert(word_size <= word_size_sum, "sanity");
685
686 // This will be the "starts humongous" region.
687 HeapRegion* first_hr = region_at(first);
688 // The header of the new object will be placed at the bottom of
689 // the first region.
690 HeapWord* new_obj = first_hr->bottom();
691 // This will be the new end of the first region in the series that
692 // should also match the end of the last region in the series.
693 HeapWord* new_end = new_obj + word_size_sum;
694 // This will be the new top of the first region that will reflect
695 // this allocation.
696 HeapWord* new_top = new_obj + word_size;
697
698 // First, we need to zero the header of the space that we will be
699 // allocating. When we update top further down, some refinement
700 // threads might try to scan the region. By zeroing the header we
701 // ensure that any thread that will try to scan the region will
702 // come across the zero klass word and bail out.
703 //
704 // NOTE: It would not have been correct to have used
705 // CollectedHeap::fill_with_object() and make the space look like
706 // an int array. The thread that is doing the allocation will
707 // later update the object header to a potentially different array
708 // type and, for a very short period of time, the klass and length
709 // fields will be inconsistent. This could cause a refinement
710 // thread to calculate the object size incorrectly.
711 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
712
713 // We will set up the first region as "starts humongous". This
714 // will also update the BOT covering all the regions to reflect
715 // that there is a single object that starts at the bottom of the
716 // first region.
717 first_hr->set_startsHumongous(new_top, new_end);
718
719 // Then, if there are any, we will set up the "continues
720 // humongous" regions.
721 HeapRegion* hr = NULL;
722 for (uint i = first + 1; i < last; ++i) {
723 hr = region_at(i);
724 hr->set_continuesHumongous(first_hr);
725 }
726 // If we have "continues humongous" regions (hr != NULL), then the
727 // end of the last one should match new_end.
728 assert(hr == NULL || hr->end() == new_end, "sanity");
729
730 // Up to this point no concurrent thread would have been able to
731 // do any scanning on any region in this series. All the top
732 // fields still point to bottom, so the intersection between
733 // [bottom,top] and [card_start,card_end] will be empty. Before we
734 // update the top fields, we'll do a storestore to make sure that
735 // no thread sees the update to top before the zeroing of the
736 // object header and the BOT initialization.
737 OrderAccess::storestore();
738
739 // Now that the BOT and the object header have been initialized,
740 // we can update top of the "starts humongous" region.
741 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
742 "new_top should be in this region");
743 first_hr->set_top(new_top);
744 if (_hr_printer.is_active()) {
745 HeapWord* bottom = first_hr->bottom();
746 HeapWord* end = first_hr->orig_end();
747 if ((first + 1) == last) {
748 // the series has a single humongous region
749 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
750 } else {
751 // the series has more than one humongous regions
752 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
753 }
754 }
755
756 // Now, we will update the top fields of the "continues humongous"
757 // regions. The reason we need to do this is that, otherwise,
758 // these regions would look empty and this will confuse parts of
759 // G1. For example, the code that looks for a consecutive number
760 // of empty regions will consider them empty and try to
761 // re-allocate them. We can extend is_empty() to also include
762 // !continuesHumongous(), but it is easier to just update the top
763 // fields here. The way we set top for all regions (i.e., top ==
764 // end for all regions but the last one, top == new_top for the
765 // last one) is actually used when we will free up the humongous
766 // region in free_humongous_region().
767 hr = NULL;
768 for (uint i = first + 1; i < last; ++i) {
769 hr = region_at(i);
770 if ((i + 1) == last) {
771 // last continues humongous region
772 assert(hr->bottom() < new_top && new_top <= hr->end(),
773 "new_top should fall on this region");
774 hr->set_top(new_top);
775 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
776 } else {
777 // not last one
778 assert(new_top > hr->end(), "new_top should be above this region");
779 hr->set_top(hr->end());
780 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
781 }
782 }
783 // If we have continues humongous regions (hr != NULL), then the
784 // end of the last one should match new_end and its top should
785 // match new_top.
786 assert(hr == NULL ||
787 (hr->end() == new_end && hr->top() == new_top), "sanity");
788
789 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
790 _summary_bytes_used += first_hr->used();
791 _humongous_set.add(first_hr);
792
793 return new_obj;
794 }
795
796 // If could fit into free regions w/o expansion, try.
797 // Otherwise, if can expand, do so.
798 // Otherwise, if using ex regions might help, try with ex given back.
799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
800 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
801
802 verify_region_sets_optional();
803
804 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
805 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
806 uint x_num = expansion_regions();
807 uint fs = _hrs.free_suffix();
808 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
809 if (first == G1_NULL_HRS_INDEX) {
810 // The only thing we can do now is attempt expansion.
811 if (fs + x_num >= num_regions) {
812 // If the number of regions we're trying to allocate for this
813 // object is at most the number of regions in the free suffix,
814 // then the call to humongous_obj_allocate_find_first() above
815 // should have succeeded and we wouldn't be here.
816 //
817 // We should only be trying to expand when the free suffix is
818 // not sufficient for the object _and_ we have some expansion
819 // room available.
820 assert(num_regions > fs, "earlier allocation should have succeeded");
821
822 ergo_verbose1(ErgoHeapSizing,
823 "attempt heap expansion",
824 ergo_format_reason("humongous allocation request failed")
825 ergo_format_byte("allocation request"),
826 word_size * HeapWordSize);
827 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
828 // Even though the heap was expanded, it might not have
829 // reached the desired size. So, we cannot assume that the
830 // allocation will succeed.
831 first = humongous_obj_allocate_find_first(num_regions, word_size);
832 }
833 }
834 }
835
836 HeapWord* result = NULL;
837 if (first != G1_NULL_HRS_INDEX) {
838 result =
839 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
840 assert(result != NULL, "it should always return a valid result");
841
842 // A successful humongous object allocation changes the used space
843 // information of the old generation so we need to recalculate the
844 // sizes and update the jstat counters here.
845 g1mm()->update_sizes();
846 }
847
848 verify_region_sets_optional();
849
850 return result;
851 }
852
853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
856
857 unsigned int dummy_gc_count_before;
858 return attempt_allocation(word_size, &dummy_gc_count_before);
859 }
860
861 HeapWord*
862 G1CollectedHeap::mem_allocate(size_t word_size,
863 bool* gc_overhead_limit_was_exceeded) {
864 assert_heap_not_locked_and_not_at_safepoint();
865
866 // Loop until the allocation is satisfied, or unsatisfied after GC.
867 for (int try_count = 1; /* we'll return */; try_count += 1) {
868 unsigned int gc_count_before;
869
870 HeapWord* result = NULL;
871 if (!isHumongous(word_size)) {
872 result = attempt_allocation(word_size, &gc_count_before);
873 } else {
874 result = attempt_allocation_humongous(word_size, &gc_count_before);
875 }
876 if (result != NULL) {
877 return result;
878 }
879
880 // Create the garbage collection operation...
881 VM_G1CollectForAllocation op(gc_count_before, word_size);
882 // ...and get the VM thread to execute it.
883 VMThread::execute(&op);
884
885 if (op.prologue_succeeded() && op.pause_succeeded()) {
886 // If the operation was successful we'll return the result even
887 // if it is NULL. If the allocation attempt failed immediately
888 // after a Full GC, it's unlikely we'll be able to allocate now.
889 HeapWord* result = op.result();
890 if (result != NULL && !isHumongous(word_size)) {
891 // Allocations that take place on VM operations do not do any
892 // card dirtying and we have to do it here. We only have to do
893 // this for non-humongous allocations, though.
894 dirty_young_block(result, word_size);
895 }
896 return result;
897 } else {
898 assert(op.result() == NULL,
899 "the result should be NULL if the VM op did not succeed");
900 }
901
902 // Give a warning if we seem to be looping forever.
903 if ((QueuedAllocationWarningCount > 0) &&
904 (try_count % QueuedAllocationWarningCount == 0)) {
905 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
906 }
907 }
908
909 ShouldNotReachHere();
910 return NULL;
911 }
912
913 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
914 unsigned int *gc_count_before_ret) {
915 // Make sure you read the note in attempt_allocation_humongous().
916
917 assert_heap_not_locked_and_not_at_safepoint();
918 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
919 "be called for humongous allocation requests");
920
921 // We should only get here after the first-level allocation attempt
922 // (attempt_allocation()) failed to allocate.
923
924 // We will loop until a) we manage to successfully perform the
925 // allocation or b) we successfully schedule a collection which
926 // fails to perform the allocation. b) is the only case when we'll
927 // return NULL.
928 HeapWord* result = NULL;
929 for (int try_count = 1; /* we'll return */; try_count += 1) {
930 bool should_try_gc;
931 unsigned int gc_count_before;
932
933 {
934 MutexLockerEx x(Heap_lock);
935
936 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
937 false /* bot_updates */);
938 if (result != NULL) {
939 return result;
940 }
941
942 // If we reach here, attempt_allocation_locked() above failed to
943 // allocate a new region. So the mutator alloc region should be NULL.
944 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
945
946 if (GC_locker::is_active_and_needs_gc()) {
947 if (g1_policy()->can_expand_young_list()) {
948 // No need for an ergo verbose message here,
949 // can_expand_young_list() does this when it returns true.
950 result = _mutator_alloc_region.attempt_allocation_force(word_size,
951 false /* bot_updates */);
952 if (result != NULL) {
953 return result;
954 }
955 }
956 should_try_gc = false;
957 } else {
958 // The GCLocker may not be active but the GCLocker initiated
959 // GC may not yet have been performed (GCLocker::needs_gc()
960 // returns true). In this case we do not try this GC and
961 // wait until the GCLocker initiated GC is performed, and
962 // then retry the allocation.
963 if (GC_locker::needs_gc()) {
964 should_try_gc = false;
965 } else {
966 // Read the GC count while still holding the Heap_lock.
967 gc_count_before = total_collections();
968 should_try_gc = true;
969 }
970 }
971 }
972
973 if (should_try_gc) {
974 bool succeeded;
975 result = do_collection_pause(word_size, gc_count_before, &succeeded);
976 if (result != NULL) {
977 assert(succeeded, "only way to get back a non-NULL result");
978 return result;
979 }
980
981 if (succeeded) {
982 // If we get here we successfully scheduled a collection which
983 // failed to allocate. No point in trying to allocate
984 // further. We'll just return NULL.
985 MutexLockerEx x(Heap_lock);
986 *gc_count_before_ret = total_collections();
987 return NULL;
988 }
989 } else {
990 // The GCLocker is either active or the GCLocker initiated
991 // GC has not yet been performed. Stall until it is and
992 // then retry the allocation.
993 GC_locker::stall_until_clear();
994 }
995
996 // We can reach here if we were unsuccessful in scheduling a
997 // collection (because another thread beat us to it) or if we were
998 // stalled due to the GC locker. In either can we should retry the
999 // allocation attempt in case another thread successfully
1000 // performed a collection and reclaimed enough space. We do the
1001 // first attempt (without holding the Heap_lock) here and the
1002 // follow-on attempt will be at the start of the next loop
1003 // iteration (after taking the Heap_lock).
1004 result = _mutator_alloc_region.attempt_allocation(word_size,
1005 false /* bot_updates */);
1006 if (result != NULL) {
1007 return result;
1008 }
1009
1010 // Give a warning if we seem to be looping forever.
1011 if ((QueuedAllocationWarningCount > 0) &&
1012 (try_count % QueuedAllocationWarningCount == 0)) {
1013 warning("G1CollectedHeap::attempt_allocation_slow() "
1014 "retries %d times", try_count);
1015 }
1016 }
1017
1018 ShouldNotReachHere();
1019 return NULL;
1020 }
1021
1022 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1023 unsigned int * gc_count_before_ret) {
1024 // The structure of this method has a lot of similarities to
1025 // attempt_allocation_slow(). The reason these two were not merged
1026 // into a single one is that such a method would require several "if
1027 // allocation is not humongous do this, otherwise do that"
1028 // conditional paths which would obscure its flow. In fact, an early
1029 // version of this code did use a unified method which was harder to
1030 // follow and, as a result, it had subtle bugs that were hard to
1031 // track down. So keeping these two methods separate allows each to
1032 // be more readable. It will be good to keep these two in sync as
1033 // much as possible.
1034
1035 assert_heap_not_locked_and_not_at_safepoint();
1036 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1037 "should only be called for humongous allocations");
1038
1039 // Humongous objects can exhaust the heap quickly, so we should check if we
1040 // need to start a marking cycle at each humongous object allocation. We do
1041 // the check before we do the actual allocation. The reason for doing it
1042 // before the allocation is that we avoid having to keep track of the newly
1043 // allocated memory while we do a GC.
1044 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1045 word_size)) {
1046 collect(GCCause::_g1_humongous_allocation);
1047 }
1048
1049 // We will loop until a) we manage to successfully perform the
1050 // allocation or b) we successfully schedule a collection which
1051 // fails to perform the allocation. b) is the only case when we'll
1052 // return NULL.
1053 HeapWord* result = NULL;
1054 for (int try_count = 1; /* we'll return */; try_count += 1) {
1055 bool should_try_gc;
1056 unsigned int gc_count_before;
1057
1058 {
1059 MutexLockerEx x(Heap_lock);
1060
1061 // Given that humongous objects are not allocated in young
1062 // regions, we'll first try to do the allocation without doing a
1063 // collection hoping that there's enough space in the heap.
1064 result = humongous_obj_allocate(word_size);
1065 if (result != NULL) {
1066 return result;
1067 }
1068
1069 if (GC_locker::is_active_and_needs_gc()) {
1070 should_try_gc = false;
1071 } else {
1072 // The GCLocker may not be active but the GCLocker initiated
1073 // GC may not yet have been performed (GCLocker::needs_gc()
1074 // returns true). In this case we do not try this GC and
1075 // wait until the GCLocker initiated GC is performed, and
1076 // then retry the allocation.
1077 if (GC_locker::needs_gc()) {
1078 should_try_gc = false;
1079 } else {
1080 // Read the GC count while still holding the Heap_lock.
1081 gc_count_before = total_collections();
1082 should_try_gc = true;
1083 }
1084 }
1085 }
1086
1087 if (should_try_gc) {
1088 // If we failed to allocate the humongous object, we should try to
1089 // do a collection pause (if we're allowed) in case it reclaims
1090 // enough space for the allocation to succeed after the pause.
1091
1092 bool succeeded;
1093 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1094 if (result != NULL) {
1095 assert(succeeded, "only way to get back a non-NULL result");
1096 return result;
1097 }
1098
1099 if (succeeded) {
1100 // If we get here we successfully scheduled a collection which
1101 // failed to allocate. No point in trying to allocate
1102 // further. We'll just return NULL.
1103 MutexLockerEx x(Heap_lock);
1104 *gc_count_before_ret = total_collections();
1105 return NULL;
1106 }
1107 } else {
1108 // The GCLocker is either active or the GCLocker initiated
1109 // GC has not yet been performed. Stall until it is and
1110 // then retry the allocation.
1111 GC_locker::stall_until_clear();
1112 }
1113
1114 // We can reach here if we were unsuccessful in scheduling a
1115 // collection (because another thread beat us to it) or if we were
1116 // stalled due to the GC locker. In either can we should retry the
1117 // allocation attempt in case another thread successfully
1118 // performed a collection and reclaimed enough space. Give a
1119 // warning if we seem to be looping forever.
1120
1121 if ((QueuedAllocationWarningCount > 0) &&
1122 (try_count % QueuedAllocationWarningCount == 0)) {
1123 warning("G1CollectedHeap::attempt_allocation_humongous() "
1124 "retries %d times", try_count);
1125 }
1126 }
1127
1128 ShouldNotReachHere();
1129 return NULL;
1130 }
1131
1132 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1133 bool expect_null_mutator_alloc_region) {
1134 assert_at_safepoint(true /* should_be_vm_thread */);
1135 assert(_mutator_alloc_region.get() == NULL ||
1136 !expect_null_mutator_alloc_region,
1137 "the current alloc region was unexpectedly found to be non-NULL");
1138
1139 if (!isHumongous(word_size)) {
1140 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1141 false /* bot_updates */);
1142 } else {
1143 HeapWord* result = humongous_obj_allocate(word_size);
1144 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1145 g1_policy()->set_initiate_conc_mark_if_possible();
1146 }
1147 return result;
1148 }
1149
1150 ShouldNotReachHere();
1151 }
1152
1153 class PostMCRemSetClearClosure: public HeapRegionClosure {
1154 G1CollectedHeap* _g1h;
1155 ModRefBarrierSet* _mr_bs;
1156 public:
1157 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1158 _g1h(g1h), _mr_bs(mr_bs) {}
1159
1160 bool doHeapRegion(HeapRegion* r) {
1161 HeapRegionRemSet* hrrs = r->rem_set();
1162
1163 if (r->continuesHumongous()) {
1164 // We'll assert that the strong code root list and RSet is empty
1165 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1166 assert(hrrs->occupied() == 0, "RSet should be empty");
1167 return false;
1168 }
1169
1170 _g1h->reset_gc_time_stamps(r);
1171 hrrs->clear();
1172 // You might think here that we could clear just the cards
1173 // corresponding to the used region. But no: if we leave a dirty card
1174 // in a region we might allocate into, then it would prevent that card
1175 // from being enqueued, and cause it to be missed.
1176 // Re: the performance cost: we shouldn't be doing full GC anyway!
1177 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1178
1179 return false;
1180 }
1181 };
1182
1183 void G1CollectedHeap::clear_rsets_post_compaction() {
1184 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1185 heap_region_iterate(&rs_clear);
1186 }
1187
1188 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1189 G1CollectedHeap* _g1h;
1190 UpdateRSOopClosure _cl;
1191 int _worker_i;
1192 public:
1193 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1194 _cl(g1->g1_rem_set(), worker_i),
1195 _worker_i(worker_i),
1196 _g1h(g1)
1197 { }
1198
1199 bool doHeapRegion(HeapRegion* r) {
1200 if (!r->continuesHumongous()) {
1201 _cl.set_from(r);
1202 r->oop_iterate(&_cl);
1203 }
1204 return false;
1205 }
1206 };
1207
1208 class ParRebuildRSTask: public AbstractGangTask {
1209 G1CollectedHeap* _g1;
1210 public:
1211 ParRebuildRSTask(G1CollectedHeap* g1)
1212 : AbstractGangTask("ParRebuildRSTask"),
1213 _g1(g1)
1214 { }
1215
1216 void work(uint worker_id) {
1217 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1218 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1219 _g1->workers()->active_workers(),
1220 HeapRegion::RebuildRSClaimValue);
1221 }
1222 };
1223
1224 class PostCompactionPrinterClosure: public HeapRegionClosure {
1225 private:
1226 G1HRPrinter* _hr_printer;
1227 public:
1228 bool doHeapRegion(HeapRegion* hr) {
1229 assert(!hr->is_young(), "not expecting to find young regions");
1230 // We only generate output for non-empty regions.
1231 if (!hr->is_empty()) {
1232 if (!hr->isHumongous()) {
1233 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1234 } else if (hr->startsHumongous()) {
1235 if (hr->region_num() == 1) {
1236 // single humongous region
1237 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1238 } else {
1239 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1240 }
1241 } else {
1242 assert(hr->continuesHumongous(), "only way to get here");
1243 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1244 }
1245 }
1246 return false;
1247 }
1248
1249 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1250 : _hr_printer(hr_printer) { }
1251 };
1252
1253 void G1CollectedHeap::print_hrs_post_compaction() {
1254 PostCompactionPrinterClosure cl(hr_printer());
1255 heap_region_iterate(&cl);
1256 }
1257
1258 bool G1CollectedHeap::do_collection(bool explicit_gc,
1259 bool clear_all_soft_refs,
1260 size_t word_size) {
1261 assert_at_safepoint(true /* should_be_vm_thread */);
1262
1263 if (GC_locker::check_active_before_gc()) {
1264 return false;
1265 }
1266
1267 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1268 gc_timer->register_gc_start();
1269
1270 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1271 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1272
1273 SvcGCMarker sgcm(SvcGCMarker::FULL);
1274 ResourceMark rm;
1275
1276 print_heap_before_gc();
1277 trace_heap_before_gc(gc_tracer);
1278
1279 HRSPhaseSetter x(HRSPhaseFullGC);
1280 verify_region_sets_optional();
1281
1282 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1283 collector_policy()->should_clear_all_soft_refs();
1284
1285 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1286
1287 {
1288 IsGCActiveMark x;
1289
1290 // Timing
1291 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1292 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1293
1294 {
1295 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1296 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1297 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1298
1299 double start = os::elapsedTime();
1300 g1_policy()->record_full_collection_start();
1301
1302 // Note: When we have a more flexible GC logging framework that
1303 // allows us to add optional attributes to a GC log record we
1304 // could consider timing and reporting how long we wait in the
1305 // following two methods.
1306 wait_while_free_regions_coming();
1307 // If we start the compaction before the CM threads finish
1308 // scanning the root regions we might trip them over as we'll
1309 // be moving objects / updating references. So let's wait until
1310 // they are done. By telling them to abort, they should complete
1311 // early.
1312 _cm->root_regions()->abort();
1313 _cm->root_regions()->wait_until_scan_finished();
1314 append_secondary_free_list_if_not_empty_with_lock();
1315
1316 gc_prologue(true);
1317 increment_total_collections(true /* full gc */);
1318 increment_old_marking_cycles_started();
1319
1320 assert(used() == recalculate_used(), "Should be equal");
1321
1322 verify_before_gc();
1323
1324 pre_full_gc_dump(gc_timer);
1325
1326 COMPILER2_PRESENT(DerivedPointerTable::clear());
1327
1328 // Disable discovery and empty the discovered lists
1329 // for the CM ref processor.
1330 ref_processor_cm()->disable_discovery();
1331 ref_processor_cm()->abandon_partial_discovery();
1332 ref_processor_cm()->verify_no_references_recorded();
1333
1334 // Abandon current iterations of concurrent marking and concurrent
1335 // refinement, if any are in progress. We have to do this before
1336 // wait_until_scan_finished() below.
1337 concurrent_mark()->abort();
1338
1339 // Make sure we'll choose a new allocation region afterwards.
1340 release_mutator_alloc_region();
1341 abandon_gc_alloc_regions();
1342 g1_rem_set()->cleanupHRRS();
1343
1344 // We should call this after we retire any currently active alloc
1345 // regions so that all the ALLOC / RETIRE events are generated
1346 // before the start GC event.
1347 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1348
1349 // We may have added regions to the current incremental collection
1350 // set between the last GC or pause and now. We need to clear the
1351 // incremental collection set and then start rebuilding it afresh
1352 // after this full GC.
1353 abandon_collection_set(g1_policy()->inc_cset_head());
1354 g1_policy()->clear_incremental_cset();
1355 g1_policy()->stop_incremental_cset_building();
1356
1357 tear_down_region_sets(false /* free_list_only */);
1358 g1_policy()->set_gcs_are_young(true);
1359
1360 // See the comments in g1CollectedHeap.hpp and
1361 // G1CollectedHeap::ref_processing_init() about
1362 // how reference processing currently works in G1.
1363
1364 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1365 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1366
1367 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1368 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1369
1370 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1371 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1372
1373 // Do collection work
1374 {
1375 HandleMark hm; // Discard invalid handles created during gc
1376 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1377 }
1378
1379 assert(free_regions() == 0, "we should not have added any free regions");
1380 rebuild_region_sets(false /* free_list_only */);
1381
1382 // Enqueue any discovered reference objects that have
1383 // not been removed from the discovered lists.
1384 ref_processor_stw()->enqueue_discovered_references();
1385
1386 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1387
1388 MemoryService::track_memory_usage();
1389
1390 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1391 ref_processor_stw()->verify_no_references_recorded();
1392
1393 // Note: since we've just done a full GC, concurrent
1394 // marking is no longer active. Therefore we need not
1395 // re-enable reference discovery for the CM ref processor.
1396 // That will be done at the start of the next marking cycle.
1397 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1398 ref_processor_cm()->verify_no_references_recorded();
1399
1400 reset_gc_time_stamp();
1401 // Since everything potentially moved, we will clear all remembered
1402 // sets, and clear all cards. Later we will rebuild remembered
1403 // sets. We will also reset the GC time stamps of the regions.
1404 clear_rsets_post_compaction();
1405 check_gc_time_stamps();
1406
1407 // Resize the heap if necessary.
1408 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1409
1410 if (_hr_printer.is_active()) {
1411 // We should do this after we potentially resize the heap so
1412 // that all the COMMIT / UNCOMMIT events are generated before
1413 // the end GC event.
1414
1415 print_hrs_post_compaction();
1416 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1417 }
1418
1419 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1420 if (hot_card_cache->use_cache()) {
1421 hot_card_cache->reset_card_counts();
1422 hot_card_cache->reset_hot_cache();
1423 }
1424
1425 // Rebuild remembered sets of all regions.
1426 if (G1CollectedHeap::use_parallel_gc_threads()) {
1427 uint n_workers =
1428 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1429 workers()->active_workers(),
1430 Threads::number_of_non_daemon_threads());
1431 assert(UseDynamicNumberOfGCThreads ||
1432 n_workers == workers()->total_workers(),
1433 "If not dynamic should be using all the workers");
1434 workers()->set_active_workers(n_workers);
1435 // Set parallel threads in the heap (_n_par_threads) only
1436 // before a parallel phase and always reset it to 0 after
1437 // the phase so that the number of parallel threads does
1438 // no get carried forward to a serial phase where there
1439 // may be code that is "possibly_parallel".
1440 set_par_threads(n_workers);
1441
1442 ParRebuildRSTask rebuild_rs_task(this);
1443 assert(check_heap_region_claim_values(
1444 HeapRegion::InitialClaimValue), "sanity check");
1445 assert(UseDynamicNumberOfGCThreads ||
1446 workers()->active_workers() == workers()->total_workers(),
1447 "Unless dynamic should use total workers");
1448 // Use the most recent number of active workers
1449 assert(workers()->active_workers() > 0,
1450 "Active workers not properly set");
1451 set_par_threads(workers()->active_workers());
1452 workers()->run_task(&rebuild_rs_task);
1453 set_par_threads(0);
1454 assert(check_heap_region_claim_values(
1455 HeapRegion::RebuildRSClaimValue), "sanity check");
1456 reset_heap_region_claim_values();
1457 } else {
1458 RebuildRSOutOfRegionClosure rebuild_rs(this);
1459 heap_region_iterate(&rebuild_rs);
1460 }
1461
1462 // Rebuild the strong code root lists for each region
1463 rebuild_strong_code_roots();
1464
1465 if (true) { // FIXME
1466 // Ask the permanent generation to adjust size for full collections
1467 perm()->compute_new_size();
1468 }
1469
1470 #ifdef TRACESPINNING
1471 ParallelTaskTerminator::print_termination_counts();
1472 #endif
1473
1474 // Discard all rset updates
1475 JavaThread::dirty_card_queue_set().abandon_logs();
1476 assert(!G1DeferredRSUpdate
1477 || (G1DeferredRSUpdate &&
1478 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1479
1480 _young_list->reset_sampled_info();
1481 // At this point there should be no regions in the
1482 // entire heap tagged as young.
1483 assert(check_young_list_empty(true /* check_heap */),
1484 "young list should be empty at this point");
1485
1486 // Update the number of full collections that have been completed.
1487 increment_old_marking_cycles_completed(false /* concurrent */);
1488
1489 _hrs.verify_optional();
1490 verify_region_sets_optional();
1491
1492 verify_after_gc();
1493
1494 // Start a new incremental collection set for the next pause
1495 assert(g1_policy()->collection_set() == NULL, "must be");
1496 g1_policy()->start_incremental_cset_building();
1497
1498 // Clear the _cset_fast_test bitmap in anticipation of adding
1499 // regions to the incremental collection set for the next
1500 // evacuation pause.
1501 clear_cset_fast_test();
1502
1503 init_mutator_alloc_region();
1504
1505 double end = os::elapsedTime();
1506 g1_policy()->record_full_collection_end();
1507
1508 if (G1Log::fine()) {
1509 g1_policy()->print_heap_transition();
1510 }
1511
1512 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1513 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1514 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1515 // before any GC notifications are raised.
1516 g1mm()->update_sizes();
1517
1518 gc_epilogue(true);
1519 }
1520
1521 if (G1Log::finer()) {
1522 g1_policy()->print_detailed_heap_transition();
1523 }
1524
1525 print_heap_after_gc();
1526 trace_heap_after_gc(gc_tracer);
1527
1528 post_full_gc_dump(gc_timer);
1529 }
1530
1531 gc_timer->register_gc_end();
1532 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1533
1534 return true;
1535 }
1536
1537 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1538 // do_collection() will return whether it succeeded in performing
1539 // the GC. Currently, there is no facility on the
1540 // do_full_collection() API to notify the caller than the collection
1541 // did not succeed (e.g., because it was locked out by the GC
1542 // locker). So, right now, we'll ignore the return value.
1543 bool dummy = do_collection(true, /* explicit_gc */
1544 clear_all_soft_refs,
1545 0 /* word_size */);
1546 }
1547
1548 // This code is mostly copied from TenuredGeneration.
1549 void
1550 G1CollectedHeap::
1551 resize_if_necessary_after_full_collection(size_t word_size) {
1552 // Include the current allocation, if any, and bytes that will be
1553 // pre-allocated to support collections, as "used".
1554 const size_t used_after_gc = used();
1555 const size_t capacity_after_gc = capacity();
1556 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1557
1558 // This is enforced in arguments.cpp.
1559 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1560 "otherwise the code below doesn't make sense");
1561
1562 // We don't have floating point command-line arguments
1563 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1564 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1565 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1566 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1567
1568 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1569 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1570
1571 // We have to be careful here as these two calculations can overflow
1572 // 32-bit size_t's.
1573 double used_after_gc_d = (double) used_after_gc;
1574 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1575 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1576
1577 // Let's make sure that they are both under the max heap size, which
1578 // by default will make them fit into a size_t.
1579 double desired_capacity_upper_bound = (double) max_heap_size;
1580 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1581 desired_capacity_upper_bound);
1582 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1583 desired_capacity_upper_bound);
1584
1585 // We can now safely turn them into size_t's.
1586 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1587 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1588
1589 // This assert only makes sense here, before we adjust them
1590 // with respect to the min and max heap size.
1591 assert(minimum_desired_capacity <= maximum_desired_capacity,
1592 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1593 "maximum_desired_capacity = "SIZE_FORMAT,
1594 minimum_desired_capacity, maximum_desired_capacity));
1595
1596 // Should not be greater than the heap max size. No need to adjust
1597 // it with respect to the heap min size as it's a lower bound (i.e.,
1598 // we'll try to make the capacity larger than it, not smaller).
1599 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1600 // Should not be less than the heap min size. No need to adjust it
1601 // with respect to the heap max size as it's an upper bound (i.e.,
1602 // we'll try to make the capacity smaller than it, not greater).
1603 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1604
1605 if (capacity_after_gc < minimum_desired_capacity) {
1606 // Don't expand unless it's significant
1607 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1608 ergo_verbose4(ErgoHeapSizing,
1609 "attempt heap expansion",
1610 ergo_format_reason("capacity lower than "
1611 "min desired capacity after Full GC")
1612 ergo_format_byte("capacity")
1613 ergo_format_byte("occupancy")
1614 ergo_format_byte_perc("min desired capacity"),
1615 capacity_after_gc, used_after_gc,
1616 minimum_desired_capacity, (double) MinHeapFreeRatio);
1617 expand(expand_bytes);
1618
1619 // No expansion, now see if we want to shrink
1620 } else if (capacity_after_gc > maximum_desired_capacity) {
1621 // Capacity too large, compute shrinking size
1622 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1623 ergo_verbose4(ErgoHeapSizing,
1624 "attempt heap shrinking",
1625 ergo_format_reason("capacity higher than "
1626 "max desired capacity after Full GC")
1627 ergo_format_byte("capacity")
1628 ergo_format_byte("occupancy")
1629 ergo_format_byte_perc("max desired capacity"),
1630 capacity_after_gc, used_after_gc,
1631 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1632 shrink(shrink_bytes);
1633 }
1634 }
1635
1636
1637 HeapWord*
1638 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1639 bool* succeeded) {
1640 assert_at_safepoint(true /* should_be_vm_thread */);
1641
1642 *succeeded = true;
1643 // Let's attempt the allocation first.
1644 HeapWord* result =
1645 attempt_allocation_at_safepoint(word_size,
1646 false /* expect_null_mutator_alloc_region */);
1647 if (result != NULL) {
1648 assert(*succeeded, "sanity");
1649 return result;
1650 }
1651
1652 // In a G1 heap, we're supposed to keep allocation from failing by
1653 // incremental pauses. Therefore, at least for now, we'll favor
1654 // expansion over collection. (This might change in the future if we can
1655 // do something smarter than full collection to satisfy a failed alloc.)
1656 result = expand_and_allocate(word_size);
1657 if (result != NULL) {
1658 assert(*succeeded, "sanity");
1659 return result;
1660 }
1661
1662 // Expansion didn't work, we'll try to do a Full GC.
1663 bool gc_succeeded = do_collection(false, /* explicit_gc */
1664 false, /* clear_all_soft_refs */
1665 word_size);
1666 if (!gc_succeeded) {
1667 *succeeded = false;
1668 return NULL;
1669 }
1670
1671 // Retry the allocation
1672 result = attempt_allocation_at_safepoint(word_size,
1673 true /* expect_null_mutator_alloc_region */);
1674 if (result != NULL) {
1675 assert(*succeeded, "sanity");
1676 return result;
1677 }
1678
1679 // Then, try a Full GC that will collect all soft references.
1680 gc_succeeded = do_collection(false, /* explicit_gc */
1681 true, /* clear_all_soft_refs */
1682 word_size);
1683 if (!gc_succeeded) {
1684 *succeeded = false;
1685 return NULL;
1686 }
1687
1688 // Retry the allocation once more
1689 result = attempt_allocation_at_safepoint(word_size,
1690 true /* expect_null_mutator_alloc_region */);
1691 if (result != NULL) {
1692 assert(*succeeded, "sanity");
1693 return result;
1694 }
1695
1696 assert(!collector_policy()->should_clear_all_soft_refs(),
1697 "Flag should have been handled and cleared prior to this point");
1698
1699 // What else? We might try synchronous finalization later. If the total
1700 // space available is large enough for the allocation, then a more
1701 // complete compaction phase than we've tried so far might be
1702 // appropriate.
1703 assert(*succeeded, "sanity");
1704 return NULL;
1705 }
1706
1707 // Attempting to expand the heap sufficiently
1708 // to support an allocation of the given "word_size". If
1709 // successful, perform the allocation and return the address of the
1710 // allocated block, or else "NULL".
1711
1712 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1713 assert_at_safepoint(true /* should_be_vm_thread */);
1714
1715 verify_region_sets_optional();
1716
1717 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1718 ergo_verbose1(ErgoHeapSizing,
1719 "attempt heap expansion",
1720 ergo_format_reason("allocation request failed")
1721 ergo_format_byte("allocation request"),
1722 word_size * HeapWordSize);
1723 if (expand(expand_bytes)) {
1724 _hrs.verify_optional();
1725 verify_region_sets_optional();
1726 return attempt_allocation_at_safepoint(word_size,
1727 false /* expect_null_mutator_alloc_region */);
1728 }
1729 return NULL;
1730 }
1731
1732 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1733 HeapWord* new_end) {
1734 assert(old_end != new_end, "don't call this otherwise");
1735 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1736
1737 // Update the committed mem region.
1738 _g1_committed.set_end(new_end);
1739 // Tell the card table about the update.
1740 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1741 // Tell the BOT about the update.
1742 _bot_shared->resize(_g1_committed.word_size());
1743 // Tell the hot card cache about the update
1744 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1745 }
1746
1747 bool G1CollectedHeap::expand(size_t expand_bytes) {
1748 size_t old_mem_size = _g1_storage.committed_size();
1749 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1750 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1751 HeapRegion::GrainBytes);
1752 ergo_verbose2(ErgoHeapSizing,
1753 "expand the heap",
1754 ergo_format_byte("requested expansion amount")
1755 ergo_format_byte("attempted expansion amount"),
1756 expand_bytes, aligned_expand_bytes);
1757
1758 // First commit the memory.
1759 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1760 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1761 if (successful) {
1762 // Then propagate this update to the necessary data structures.
1763 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1764 update_committed_space(old_end, new_end);
1765
1766 FreeRegionList expansion_list("Local Expansion List");
1767 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1768 assert(mr.start() == old_end, "post-condition");
1769 // mr might be a smaller region than what was requested if
1770 // expand_by() was unable to allocate the HeapRegion instances
1771 assert(mr.end() <= new_end, "post-condition");
1772
1773 size_t actual_expand_bytes = mr.byte_size();
1774 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1775 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1776 "post-condition");
1777 if (actual_expand_bytes < aligned_expand_bytes) {
1778 // We could not expand _hrs to the desired size. In this case we
1779 // need to shrink the committed space accordingly.
1780 assert(mr.end() < new_end, "invariant");
1781
1782 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1783 // First uncommit the memory.
1784 _g1_storage.shrink_by(diff_bytes);
1785 // Then propagate this update to the necessary data structures.
1786 update_committed_space(new_end, mr.end());
1787 }
1788 _free_list.add_as_tail(&expansion_list);
1789
1790 if (_hr_printer.is_active()) {
1791 HeapWord* curr = mr.start();
1792 while (curr < mr.end()) {
1793 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1794 _hr_printer.commit(curr, curr_end);
1795 curr = curr_end;
1796 }
1797 assert(curr == mr.end(), "post-condition");
1798 }
1799 g1_policy()->record_new_heap_size(n_regions());
1800 } else {
1801 ergo_verbose0(ErgoHeapSizing,
1802 "did not expand the heap",
1803 ergo_format_reason("heap expansion operation failed"));
1804 // The expansion of the virtual storage space was unsuccessful.
1805 // Let's see if it was because we ran out of swap.
1806 if (G1ExitOnExpansionFailure &&
1807 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1808 // We had head room...
1809 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1810 }
1811 }
1812 return successful;
1813 }
1814
1815 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1816 size_t old_mem_size = _g1_storage.committed_size();
1817 size_t aligned_shrink_bytes =
1818 ReservedSpace::page_align_size_down(shrink_bytes);
1819 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1820 HeapRegion::GrainBytes);
1821 uint num_regions_deleted = 0;
1822 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1823 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1824 assert(mr.end() == old_end, "post-condition");
1825
1826 ergo_verbose3(ErgoHeapSizing,
1827 "shrink the heap",
1828 ergo_format_byte("requested shrinking amount")
1829 ergo_format_byte("aligned shrinking amount")
1830 ergo_format_byte("attempted shrinking amount"),
1831 shrink_bytes, aligned_shrink_bytes, mr.byte_size());
1832 if (mr.byte_size() > 0) {
1833 if (_hr_printer.is_active()) {
1834 HeapWord* curr = mr.end();
1835 while (curr > mr.start()) {
1836 HeapWord* curr_end = curr;
1837 curr -= HeapRegion::GrainWords;
1838 _hr_printer.uncommit(curr, curr_end);
1839 }
1840 assert(curr == mr.start(), "post-condition");
1841 }
1842
1843 _g1_storage.shrink_by(mr.byte_size());
1844 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1845 assert(mr.start() == new_end, "post-condition");
1846
1847 _expansion_regions += num_regions_deleted;
1848 update_committed_space(old_end, new_end);
1849 HeapRegionRemSet::shrink_heap(n_regions());
1850 g1_policy()->record_new_heap_size(n_regions());
1851 } else {
1852 ergo_verbose0(ErgoHeapSizing,
1853 "did not shrink the heap",
1854 ergo_format_reason("heap shrinking operation failed"));
1855 }
1856 }
1857
1858 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1859 verify_region_sets_optional();
1860
1861 // We should only reach here at the end of a Full GC which means we
1862 // should not not be holding to any GC alloc regions. The method
1863 // below will make sure of that and do any remaining clean up.
1864 abandon_gc_alloc_regions();
1865
1866 // Instead of tearing down / rebuilding the free lists here, we
1867 // could instead use the remove_all_pending() method on free_list to
1868 // remove only the ones that we need to remove.
1869 tear_down_region_sets(true /* free_list_only */);
1870 shrink_helper(shrink_bytes);
1871 rebuild_region_sets(true /* free_list_only */);
1872
1873 _hrs.verify_optional();
1874 verify_region_sets_optional();
1875 }
1876
1877 // Public methods.
1878
1879 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1880 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1881 #endif // _MSC_VER
1882
1883
1884 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1885 SharedHeap(policy_),
1886 _g1_policy(policy_),
1887 _dirty_card_queue_set(false),
1888 _into_cset_dirty_card_queue_set(false),
1889 _is_alive_closure_cm(this),
1890 _is_alive_closure_stw(this),
1891 _ref_processor_cm(NULL),
1892 _ref_processor_stw(NULL),
1893 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1894 _bot_shared(NULL),
1895 _evac_failure_scan_stack(NULL),
1896 _mark_in_progress(false),
1897 _cg1r(NULL), _summary_bytes_used(0),
1898 _g1mm(NULL),
1899 _refine_cte_cl(NULL),
1900 _full_collection(false),
1901 _free_list("Master Free List"),
1902 _secondary_free_list("Secondary Free List"),
1903 _old_set("Old Set"),
1904 _humongous_set("Master Humongous Set"),
1905 _free_regions_coming(false),
1906 _young_list(new YoungList(this)),
1907 _gc_time_stamp(0),
1908 _retained_old_gc_alloc_region(NULL),
1909 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1910 _old_plab_stats(OldPLABSize, PLABWeight),
1911 _expand_heap_after_alloc_failure(true),
1912 _surviving_young_words(NULL),
1913 _old_marking_cycles_started(0),
1914 _old_marking_cycles_completed(0),
1915 _concurrent_cycle_started(false),
1916 _in_cset_fast_test(NULL),
1917 _in_cset_fast_test_base(NULL),
1918 _dirty_cards_region_list(NULL),
1919 _worker_cset_start_region(NULL),
1920 _worker_cset_start_region_time_stamp(NULL),
1921 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1922 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1923 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1924 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1925
1926 _g1h = this;
1927 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1928 vm_exit_during_initialization("Failed necessary allocation.");
1929 }
1930
1931 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1932
1933 int n_queues = MAX2((int)ParallelGCThreads, 1);
1934 _task_queues = new RefToScanQueueSet(n_queues);
1935
1936 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1937 assert(n_rem_sets > 0, "Invariant.");
1938
1939 HeapRegionRemSetIterator** iter_arr = NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues, mtGC);
1940 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1941 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1942 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1943
1944 for (int i = 0; i < n_queues; i++) {
1945 RefToScanQueue* q = new RefToScanQueue();
1946 q->initialize();
1947 _task_queues->register_queue(i, q);
1948 iter_arr[i] = new HeapRegionRemSetIterator();
1949 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1950 }
1951 _rem_set_iterator = iter_arr;
1952
1953 clear_cset_start_regions();
1954
1955 // Initialize the G1EvacuationFailureALot counters and flags.
1956 NOT_PRODUCT(reset_evacuation_should_fail();)
1957
1958 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1959 }
1960
1961 jint G1CollectedHeap::initialize() {
1962 CollectedHeap::pre_initialize();
1963 os::enable_vtime();
1964
1965 G1Log::init();
1966
1967 // Necessary to satisfy locking discipline assertions.
1968
1969 MutexLocker x(Heap_lock);
1970
1971 // We have to initialize the printer before committing the heap, as
1972 // it will be used then.
1973 _hr_printer.set_active(G1PrintHeapRegions);
1974
1975 // While there are no constraints in the GC code that HeapWordSize
1976 // be any particular value, there are multiple other areas in the
1977 // system which believe this to be true (e.g. oop->object_size in some
1978 // cases incorrectly returns the size in wordSize units rather than
1979 // HeapWordSize).
1980 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1981
1982 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1983 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1984 size_t heap_alignment = collector_policy()->max_alignment();
1985
1986 // Ensure that the sizes are properly aligned.
1987 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1988 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1989 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1990
1991 _cg1r = new ConcurrentG1Refine(this);
1992
1993 // Reserve the maximum.
1994 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1995 // Includes the perm-gen.
1996
1997 // When compressed oops are enabled, the preferred heap base
1998 // is calculated by subtracting the requested size from the
1999 // 32Gb boundary and using the result as the base address for
2000 // heap reservation. If the requested size is not aligned to
2001 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2002 // into the ReservedHeapSpace constructor) then the actual
2003 // base of the reserved heap may end up differing from the
2004 // address that was requested (i.e. the preferred heap base).
2005 // If this happens then we could end up using a non-optimal
2006 // compressed oops mode.
2007
2008 // Since max_byte_size is aligned to the size of a heap region (checked
2009 // above), we also need to align the perm gen size as it might not be.
2010 size_t total_reserved = 0;
2011
2012 total_reserved = add_and_check_overflow(total_reserved, max_byte_size);
2013 size_t pg_max_size = (size_t) align_size_up(pgs->max_size(), heap_alignment);
2014 total_reserved = add_and_check_overflow(total_reserved, pg_max_size);
2015
2016 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
2017
2018 char* addr = Universe::preferred_heap_base(total_reserved, heap_alignment, Universe::UnscaledNarrowOop);
2019
2020 ReservedHeapSpace heap_rs(total_reserved, heap_alignment,
2021 UseLargePages, addr);
2022
2023 if (UseCompressedOops) {
2024 if (addr != NULL && !heap_rs.is_reserved()) {
2025 // Failed to reserve at specified address - the requested memory
2026 // region is taken already, for example, by 'java' launcher.
2027 // Try again to reserver heap higher.
2028 addr = Universe::preferred_heap_base(total_reserved, heap_alignment, Universe::ZeroBasedNarrowOop);
2029
2030 ReservedHeapSpace heap_rs0(total_reserved, heap_alignment,
2031 UseLargePages, addr);
2032
2033 if (addr != NULL && !heap_rs0.is_reserved()) {
2034 // Failed to reserve at specified address again - give up.
2035 addr = Universe::preferred_heap_base(total_reserved, heap_alignment, Universe::HeapBasedNarrowOop);
2036 assert(addr == NULL, "");
2037
2038 ReservedHeapSpace heap_rs1(total_reserved, heap_alignment,
2039 UseLargePages, addr);
2040 heap_rs = heap_rs1;
2041 } else {
2042 heap_rs = heap_rs0;
2043 }
2044 }
2045 }
2046
2047 if (!heap_rs.is_reserved()) {
2048 vm_exit_during_initialization("Could not reserve enough space for object heap");
2049 return JNI_ENOMEM;
2050 }
2051
2052 // It is important to do this in a way such that concurrent readers can't
2053 // temporarily think something is in the heap. (I've actually seen this
2054 // happen in asserts: DLD.)
2055 _reserved.set_word_size(0);
2056 _reserved.set_start((HeapWord*)heap_rs.base());
2057 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2058
2059 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2060
2061 // Create the gen rem set (and barrier set) for the entire reserved region.
2062 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2063 set_barrier_set(rem_set()->bs());
2064 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2065 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2066 return JNI_ENOMEM;
2067 }
2068
2069 // Also create a G1 rem set.
2070 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2071
2072 // Carve out the G1 part of the heap.
2073
2074 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2075 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2076 g1_rs.size()/HeapWordSize);
2077 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
2078
2079 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2080
2081 _g1_storage.initialize(g1_rs, 0);
2082 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2083 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2084 (HeapWord*) _g1_reserved.end(),
2085 _expansion_regions);
2086
2087 // Do later initialization work for concurrent refinement.
2088 _cg1r->init();
2089
2090 // 6843694 - ensure that the maximum region index can fit
2091 // in the remembered set structures.
2092 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2093 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2094
2095 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2096 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2097 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2098 "too many cards per region");
2099
2100 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2101
2102 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2103 heap_word_size(init_byte_size));
2104
2105 _g1h = this;
2106
2107 _in_cset_fast_test_length = max_regions();
2108 _in_cset_fast_test_base =
2109 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2110
2111 // We're biasing _in_cset_fast_test to avoid subtracting the
2112 // beginning of the heap every time we want to index; basically
2113 // it's the same with what we do with the card table.
2114 _in_cset_fast_test = _in_cset_fast_test_base -
2115 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2116
2117 // Clear the _cset_fast_test bitmap in anticipation of adding
2118 // regions to the incremental collection set for the first
2119 // evacuation pause.
2120 clear_cset_fast_test();
2121
2122 // Create the ConcurrentMark data structure and thread.
2123 // (Must do this late, so that "max_regions" is defined.)
2124 _cm = new ConcurrentMark(heap_rs, max_regions());
2125 _cmThread = _cm->cmThread();
2126
2127 // Initialize the from_card cache structure of HeapRegionRemSet.
2128 HeapRegionRemSet::init_heap(max_regions());
2129
2130 // Now expand into the initial heap size.
2131 if (!expand(init_byte_size)) {
2132 vm_exit_during_initialization("Failed to allocate initial heap.");
2133 return JNI_ENOMEM;
2134 }
2135
2136 // Perform any initialization actions delegated to the policy.
2137 g1_policy()->init();
2138
2139 _refine_cte_cl =
2140 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2141 g1_rem_set(),
2142 concurrent_g1_refine());
2143 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2144
2145 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2146 SATB_Q_FL_lock,
2147 G1SATBProcessCompletedThreshold,
2148 Shared_SATB_Q_lock);
2149
2150 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2151 DirtyCardQ_FL_lock,
2152 concurrent_g1_refine()->yellow_zone(),
2153 concurrent_g1_refine()->red_zone(),
2154 Shared_DirtyCardQ_lock);
2155
2156 if (G1DeferredRSUpdate) {
2157 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2158 DirtyCardQ_FL_lock,
2159 -1, // never trigger processing
2160 -1, // no limit on length
2161 Shared_DirtyCardQ_lock,
2162 &JavaThread::dirty_card_queue_set());
2163 }
2164
2165 // Initialize the card queue set used to hold cards containing
2166 // references into the collection set.
2167 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2168 DirtyCardQ_FL_lock,
2169 -1, // never trigger processing
2170 -1, // no limit on length
2171 Shared_DirtyCardQ_lock,
2172 &JavaThread::dirty_card_queue_set());
2173
2174 // In case we're keeping closure specialization stats, initialize those
2175 // counts and that mechanism.
2176 SpecializationStats::clear();
2177
2178 // Here we allocate the dummy full region that is required by the
2179 // G1AllocRegion class. If we don't pass an address in the reserved
2180 // space here, lots of asserts fire.
2181
2182 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2183 _g1_reserved.start());
2184 // We'll re-use the same region whether the alloc region will
2185 // require BOT updates or not and, if it doesn't, then a non-young
2186 // region will complain that it cannot support allocations without
2187 // BOT updates. So we'll tag the dummy region as young to avoid that.
2188 dummy_region->set_young();
2189 // Make sure it's full.
2190 dummy_region->set_top(dummy_region->end());
2191 G1AllocRegion::setup(this, dummy_region);
2192
2193 init_mutator_alloc_region();
2194
2195 // Do create of the monitoring and management support so that
2196 // values in the heap have been properly initialized.
2197 _g1mm = new G1MonitoringSupport(this);
2198
2199 return JNI_OK;
2200 }
2201
2202 void G1CollectedHeap::ref_processing_init() {
2203 // Reference processing in G1 currently works as follows:
2204 //
2205 // * There are two reference processor instances. One is
2206 // used to record and process discovered references
2207 // during concurrent marking; the other is used to
2208 // record and process references during STW pauses
2209 // (both full and incremental).
2210 // * Both ref processors need to 'span' the entire heap as
2211 // the regions in the collection set may be dotted around.
2212 //
2213 // * For the concurrent marking ref processor:
2214 // * Reference discovery is enabled at initial marking.
2215 // * Reference discovery is disabled and the discovered
2216 // references processed etc during remarking.
2217 // * Reference discovery is MT (see below).
2218 // * Reference discovery requires a barrier (see below).
2219 // * Reference processing may or may not be MT
2220 // (depending on the value of ParallelRefProcEnabled
2221 // and ParallelGCThreads).
2222 // * A full GC disables reference discovery by the CM
2223 // ref processor and abandons any entries on it's
2224 // discovered lists.
2225 //
2226 // * For the STW processor:
2227 // * Non MT discovery is enabled at the start of a full GC.
2228 // * Processing and enqueueing during a full GC is non-MT.
2229 // * During a full GC, references are processed after marking.
2230 //
2231 // * Discovery (may or may not be MT) is enabled at the start
2232 // of an incremental evacuation pause.
2233 // * References are processed near the end of a STW evacuation pause.
2234 // * For both types of GC:
2235 // * Discovery is atomic - i.e. not concurrent.
2236 // * Reference discovery will not need a barrier.
2237
2238 SharedHeap::ref_processing_init();
2239 MemRegion mr = reserved_region();
2240
2241 // Concurrent Mark ref processor
2242 _ref_processor_cm =
2243 new ReferenceProcessor(mr, // span
2244 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2245 // mt processing
2246 (int) ParallelGCThreads,
2247 // degree of mt processing
2248 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2249 // mt discovery
2250 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2251 // degree of mt discovery
2252 false,
2253 // Reference discovery is not atomic
2254 &_is_alive_closure_cm,
2255 // is alive closure
2256 // (for efficiency/performance)
2257 true);
2258 // Setting next fields of discovered
2259 // lists requires a barrier.
2260
2261 // STW ref processor
2262 _ref_processor_stw =
2263 new ReferenceProcessor(mr, // span
2264 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2265 // mt processing
2266 MAX2((int)ParallelGCThreads, 1),
2267 // degree of mt processing
2268 (ParallelGCThreads > 1),
2269 // mt discovery
2270 MAX2((int)ParallelGCThreads, 1),
2271 // degree of mt discovery
2272 true,
2273 // Reference discovery is atomic
2274 &_is_alive_closure_stw,
2275 // is alive closure
2276 // (for efficiency/performance)
2277 false);
2278 // Setting next fields of discovered
2279 // lists requires a barrier.
2280 }
2281
2282 size_t G1CollectedHeap::capacity() const {
2283 return _g1_committed.byte_size();
2284 }
2285
2286 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2287 assert(!hr->continuesHumongous(), "pre-condition");
2288 hr->reset_gc_time_stamp();
2289 if (hr->startsHumongous()) {
2290 uint first_index = hr->hrs_index() + 1;
2291 uint last_index = hr->last_hc_index();
2292 for (uint i = first_index; i < last_index; i += 1) {
2293 HeapRegion* chr = region_at(i);
2294 assert(chr->continuesHumongous(), "sanity");
2295 chr->reset_gc_time_stamp();
2296 }
2297 }
2298 }
2299
2300 #ifndef PRODUCT
2301 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2302 private:
2303 unsigned _gc_time_stamp;
2304 bool _failures;
2305
2306 public:
2307 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2308 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2309
2310 virtual bool doHeapRegion(HeapRegion* hr) {
2311 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2312 if (_gc_time_stamp != region_gc_time_stamp) {
2313 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2314 "expected %d", HR_FORMAT_PARAMS(hr),
2315 region_gc_time_stamp, _gc_time_stamp);
2316 _failures = true;
2317 }
2318 return false;
2319 }
2320
2321 bool failures() { return _failures; }
2322 };
2323
2324 void G1CollectedHeap::check_gc_time_stamps() {
2325 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2326 heap_region_iterate(&cl);
2327 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2328 }
2329 #endif // PRODUCT
2330
2331 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2332 DirtyCardQueue* into_cset_dcq,
2333 bool concurrent,
2334 int worker_i) {
2335 // Clean cards in the hot card cache
2336 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2337 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2338
2339 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2340 int n_completed_buffers = 0;
2341 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2342 n_completed_buffers++;
2343 }
2344 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2345 dcqs.clear_n_completed_buffers();
2346 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2347 }
2348
2349
2350 // Computes the sum of the storage used by the various regions.
2351
2352 size_t G1CollectedHeap::used() const {
2353 assert(Heap_lock->owner() != NULL,
2354 "Should be owned on this thread's behalf.");
2355 size_t result = _summary_bytes_used;
2356 // Read only once in case it is set to NULL concurrently
2357 HeapRegion* hr = _mutator_alloc_region.get();
2358 if (hr != NULL)
2359 result += hr->used();
2360 return result;
2361 }
2362
2363 size_t G1CollectedHeap::used_unlocked() const {
2364 size_t result = _summary_bytes_used;
2365 return result;
2366 }
2367
2368 class SumUsedClosure: public HeapRegionClosure {
2369 size_t _used;
2370 public:
2371 SumUsedClosure() : _used(0) {}
2372 bool doHeapRegion(HeapRegion* r) {
2373 if (!r->continuesHumongous()) {
2374 _used += r->used();
2375 }
2376 return false;
2377 }
2378 size_t result() { return _used; }
2379 };
2380
2381 size_t G1CollectedHeap::recalculate_used() const {
2382 SumUsedClosure blk;
2383 heap_region_iterate(&blk);
2384 return blk.result();
2385 }
2386
2387 size_t G1CollectedHeap::unsafe_max_alloc() {
2388 if (free_regions() > 0) return HeapRegion::GrainBytes;
2389 // otherwise, is there space in the current allocation region?
2390
2391 // We need to store the current allocation region in a local variable
2392 // here. The problem is that this method doesn't take any locks and
2393 // there may be other threads which overwrite the current allocation
2394 // region field. attempt_allocation(), for example, sets it to NULL
2395 // and this can happen *after* the NULL check here but before the call
2396 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2397 // to be a problem in the optimized build, since the two loads of the
2398 // current allocation region field are optimized away.
2399 HeapRegion* hr = _mutator_alloc_region.get();
2400 if (hr == NULL) {
2401 return 0;
2402 }
2403 return hr->free();
2404 }
2405
2406 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2407 switch (cause) {
2408 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2409 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2410 case GCCause::_g1_humongous_allocation: return true;
2411 default: return false;
2412 }
2413 }
2414
2415 #ifndef PRODUCT
2416 void G1CollectedHeap::allocate_dummy_regions() {
2417 // Let's fill up most of the region
2418 size_t word_size = HeapRegion::GrainWords - 1024;
2419 // And as a result the region we'll allocate will be humongous.
2420 guarantee(isHumongous(word_size), "sanity");
2421
2422 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2423 // Let's use the existing mechanism for the allocation
2424 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2425 if (dummy_obj != NULL) {
2426 MemRegion mr(dummy_obj, word_size);
2427 CollectedHeap::fill_with_object(mr);
2428 } else {
2429 // If we can't allocate once, we probably cannot allocate
2430 // again. Let's get out of the loop.
2431 break;
2432 }
2433 }
2434 }
2435 #endif // !PRODUCT
2436
2437 void G1CollectedHeap::increment_old_marking_cycles_started() {
2438 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2439 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2440 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2441 _old_marking_cycles_started, _old_marking_cycles_completed));
2442
2443 _old_marking_cycles_started++;
2444 }
2445
2446 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2447 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2448
2449 // We assume that if concurrent == true, then the caller is a
2450 // concurrent thread that was joined the Suspendible Thread
2451 // Set. If there's ever a cheap way to check this, we should add an
2452 // assert here.
2453
2454 // Given that this method is called at the end of a Full GC or of a
2455 // concurrent cycle, and those can be nested (i.e., a Full GC can
2456 // interrupt a concurrent cycle), the number of full collections
2457 // completed should be either one (in the case where there was no
2458 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2459 // behind the number of full collections started.
2460
2461 // This is the case for the inner caller, i.e. a Full GC.
2462 assert(concurrent ||
2463 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2464 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2465 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2466 "is inconsistent with _old_marking_cycles_completed = %u",
2467 _old_marking_cycles_started, _old_marking_cycles_completed));
2468
2469 // This is the case for the outer caller, i.e. the concurrent cycle.
2470 assert(!concurrent ||
2471 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2472 err_msg("for outer caller (concurrent cycle): "
2473 "_old_marking_cycles_started = %u "
2474 "is inconsistent with _old_marking_cycles_completed = %u",
2475 _old_marking_cycles_started, _old_marking_cycles_completed));
2476
2477 _old_marking_cycles_completed += 1;
2478
2479 // We need to clear the "in_progress" flag in the CM thread before
2480 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2481 // is set) so that if a waiter requests another System.gc() it doesn't
2482 // incorrectly see that a marking cycle is still in progress.
2483 if (concurrent) {
2484 _cmThread->clear_in_progress();
2485 }
2486
2487 // This notify_all() will ensure that a thread that called
2488 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2489 // and it's waiting for a full GC to finish will be woken up. It is
2490 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2491 FullGCCount_lock->notify_all();
2492 }
2493
2494 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2495 _concurrent_cycle_started = true;
2496 _gc_timer_cm->register_gc_start(start_time);
2497
2498 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2499 trace_heap_before_gc(_gc_tracer_cm);
2500 }
2501
2502 void G1CollectedHeap::register_concurrent_cycle_end() {
2503 if (_concurrent_cycle_started) {
2504 _gc_timer_cm->register_gc_end();
2505
2506 if (_cm->has_aborted()) {
2507 _gc_tracer_cm->report_concurrent_mode_failure();
2508 }
2509 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2510
2511 _concurrent_cycle_started = false;
2512 }
2513 }
2514
2515 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2516 if (_concurrent_cycle_started) {
2517 trace_heap_after_gc(_gc_tracer_cm);
2518 }
2519 }
2520
2521 G1YCType G1CollectedHeap::yc_type() {
2522 bool is_young = g1_policy()->gcs_are_young();
2523 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2524 bool is_during_mark = mark_in_progress();
2525
2526 if (is_initial_mark) {
2527 return InitialMark;
2528 } else if (is_during_mark) {
2529 return DuringMark;
2530 } else if (is_young) {
2531 return Normal;
2532 } else {
2533 return Mixed;
2534 }
2535 }
2536
2537 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2538 assert_at_safepoint(true /* should_be_vm_thread */);
2539 GCCauseSetter gcs(this, cause);
2540 switch (cause) {
2541 case GCCause::_heap_inspection:
2542 case GCCause::_heap_dump: {
2543 HandleMark hm;
2544 do_full_collection(false); // don't clear all soft refs
2545 break;
2546 }
2547 default: // XXX FIX ME
2548 ShouldNotReachHere(); // Unexpected use of this function
2549 }
2550 }
2551
2552 void G1CollectedHeap::collect(GCCause::Cause cause) {
2553 assert_heap_not_locked();
2554
2555 unsigned int gc_count_before;
2556 unsigned int old_marking_count_before;
2557 bool retry_gc;
2558
2559 do {
2560 retry_gc = false;
2561
2562 {
2563 MutexLocker ml(Heap_lock);
2564
2565 // Read the GC count while holding the Heap_lock
2566 gc_count_before = total_collections();
2567 old_marking_count_before = _old_marking_cycles_started;
2568 }
2569
2570 if (should_do_concurrent_full_gc(cause)) {
2571 // Schedule an initial-mark evacuation pause that will start a
2572 // concurrent cycle. We're setting word_size to 0 which means that
2573 // we are not requesting a post-GC allocation.
2574 VM_G1IncCollectionPause op(gc_count_before,
2575 0, /* word_size */
2576 true, /* should_initiate_conc_mark */
2577 g1_policy()->max_pause_time_ms(),
2578 cause);
2579
2580 VMThread::execute(&op);
2581 if (!op.pause_succeeded()) {
2582 if (old_marking_count_before == _old_marking_cycles_started) {
2583 retry_gc = op.should_retry_gc();
2584 } else {
2585 // A Full GC happened while we were trying to schedule the
2586 // initial-mark GC. No point in starting a new cycle given
2587 // that the whole heap was collected anyway.
2588 }
2589
2590 if (retry_gc) {
2591 if (GC_locker::is_active_and_needs_gc()) {
2592 GC_locker::stall_until_clear();
2593 }
2594 }
2595 }
2596 } else {
2597 if (cause == GCCause::_gc_locker
2598 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2599
2600 // Schedule a standard evacuation pause. We're setting word_size
2601 // to 0 which means that we are not requesting a post-GC allocation.
2602 VM_G1IncCollectionPause op(gc_count_before,
2603 0, /* word_size */
2604 false, /* should_initiate_conc_mark */
2605 g1_policy()->max_pause_time_ms(),
2606 cause);
2607 VMThread::execute(&op);
2608 } else {
2609 // Schedule a Full GC.
2610 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2611 VMThread::execute(&op);
2612 }
2613 }
2614 } while (retry_gc);
2615 }
2616
2617 bool G1CollectedHeap::is_in(const void* p) const {
2618 if (_g1_committed.contains(p)) {
2619 // Given that we know that p is in the committed space,
2620 // heap_region_containing_raw() should successfully
2621 // return the containing region.
2622 HeapRegion* hr = heap_region_containing_raw(p);
2623 return hr->is_in(p);
2624 } else {
2625 return _perm_gen->as_gen()->is_in(p);
2626 }
2627 }
2628
2629 // Iteration functions.
2630
2631 // Iterates an OopClosure over all ref-containing fields of objects
2632 // within a HeapRegion.
2633
2634 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2635 MemRegion _mr;
2636 OopClosure* _cl;
2637 public:
2638 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2639 : _mr(mr), _cl(cl) {}
2640 bool doHeapRegion(HeapRegion* r) {
2641 if (!r->continuesHumongous()) {
2642 r->oop_iterate(_cl);
2643 }
2644 return false;
2645 }
2646 };
2647
2648 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2649 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2650 heap_region_iterate(&blk);
2651 if (do_perm) {
2652 perm_gen()->oop_iterate(cl);
2653 }
2654 }
2655
2656 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2657 IterateOopClosureRegionClosure blk(mr, cl);
2658 heap_region_iterate(&blk);
2659 if (do_perm) {
2660 perm_gen()->oop_iterate(cl);
2661 }
2662 }
2663
2664 // Iterates an ObjectClosure over all objects within a HeapRegion.
2665
2666 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2667 ObjectClosure* _cl;
2668 public:
2669 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2670 bool doHeapRegion(HeapRegion* r) {
2671 if (! r->continuesHumongous()) {
2672 r->object_iterate(_cl);
2673 }
2674 return false;
2675 }
2676 };
2677
2678 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2679 IterateObjectClosureRegionClosure blk(cl);
2680 heap_region_iterate(&blk);
2681 if (do_perm) {
2682 perm_gen()->object_iterate(cl);
2683 }
2684 }
2685
2686 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2687 // FIXME: is this right?
2688 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2689 }
2690
2691 // Calls a SpaceClosure on a HeapRegion.
2692
2693 class SpaceClosureRegionClosure: public HeapRegionClosure {
2694 SpaceClosure* _cl;
2695 public:
2696 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2697 bool doHeapRegion(HeapRegion* r) {
2698 _cl->do_space(r);
2699 return false;
2700 }
2701 };
2702
2703 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2704 SpaceClosureRegionClosure blk(cl);
2705 heap_region_iterate(&blk);
2706 }
2707
2708 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2709 _hrs.iterate(cl);
2710 }
2711
2712 void
2713 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2714 uint worker_id,
2715 uint no_of_par_workers,
2716 jint claim_value) {
2717 const uint regions = n_regions();
2718 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2719 no_of_par_workers :
2720 1);
2721 assert(UseDynamicNumberOfGCThreads ||
2722 no_of_par_workers == workers()->total_workers(),
2723 "Non dynamic should use fixed number of workers");
2724 // try to spread out the starting points of the workers
2725 const HeapRegion* start_hr =
2726 start_region_for_worker(worker_id, no_of_par_workers);
2727 const uint start_index = start_hr->hrs_index();
2728
2729 // each worker will actually look at all regions
2730 for (uint count = 0; count < regions; ++count) {
2731 const uint index = (start_index + count) % regions;
2732 assert(0 <= index && index < regions, "sanity");
2733 HeapRegion* r = region_at(index);
2734 // we'll ignore "continues humongous" regions (we'll process them
2735 // when we come across their corresponding "start humongous"
2736 // region) and regions already claimed
2737 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2738 continue;
2739 }
2740 // OK, try to claim it
2741 if (r->claimHeapRegion(claim_value)) {
2742 // success!
2743 assert(!r->continuesHumongous(), "sanity");
2744 if (r->startsHumongous()) {
2745 // If the region is "starts humongous" we'll iterate over its
2746 // "continues humongous" first; in fact we'll do them
2747 // first. The order is important. In on case, calling the
2748 // closure on the "starts humongous" region might de-allocate
2749 // and clear all its "continues humongous" regions and, as a
2750 // result, we might end up processing them twice. So, we'll do
2751 // them first (notice: most closures will ignore them anyway) and
2752 // then we'll do the "starts humongous" region.
2753 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2754 HeapRegion* chr = region_at(ch_index);
2755
2756 // if the region has already been claimed or it's not
2757 // "continues humongous" we're done
2758 if (chr->claim_value() == claim_value ||
2759 !chr->continuesHumongous()) {
2760 break;
2761 }
2762
2763 // Noone should have claimed it directly. We can given
2764 // that we claimed its "starts humongous" region.
2765 assert(chr->claim_value() != claim_value, "sanity");
2766 assert(chr->humongous_start_region() == r, "sanity");
2767
2768 if (chr->claimHeapRegion(claim_value)) {
2769 // we should always be able to claim it; noone else should
2770 // be trying to claim this region
2771
2772 bool res2 = cl->doHeapRegion(chr);
2773 assert(!res2, "Should not abort");
2774
2775 // Right now, this holds (i.e., no closure that actually
2776 // does something with "continues humongous" regions
2777 // clears them). We might have to weaken it in the future,
2778 // but let's leave these two asserts here for extra safety.
2779 assert(chr->continuesHumongous(), "should still be the case");
2780 assert(chr->humongous_start_region() == r, "sanity");
2781 } else {
2782 guarantee(false, "we should not reach here");
2783 }
2784 }
2785 }
2786
2787 assert(!r->continuesHumongous(), "sanity");
2788 bool res = cl->doHeapRegion(r);
2789 assert(!res, "Should not abort");
2790 }
2791 }
2792 }
2793
2794 class ResetClaimValuesClosure: public HeapRegionClosure {
2795 public:
2796 bool doHeapRegion(HeapRegion* r) {
2797 r->set_claim_value(HeapRegion::InitialClaimValue);
2798 return false;
2799 }
2800 };
2801
2802 void G1CollectedHeap::reset_heap_region_claim_values() {
2803 ResetClaimValuesClosure blk;
2804 heap_region_iterate(&blk);
2805 }
2806
2807 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2808 ResetClaimValuesClosure blk;
2809 collection_set_iterate(&blk);
2810 }
2811
2812 #ifdef ASSERT
2813 // This checks whether all regions in the heap have the correct claim
2814 // value. I also piggy-backed on this a check to ensure that the
2815 // humongous_start_region() information on "continues humongous"
2816 // regions is correct.
2817
2818 class CheckClaimValuesClosure : public HeapRegionClosure {
2819 private:
2820 jint _claim_value;
2821 uint _failures;
2822 HeapRegion* _sh_region;
2823
2824 public:
2825 CheckClaimValuesClosure(jint claim_value) :
2826 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2827 bool doHeapRegion(HeapRegion* r) {
2828 if (r->claim_value() != _claim_value) {
2829 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2830 "claim value = %d, should be %d",
2831 HR_FORMAT_PARAMS(r),
2832 r->claim_value(), _claim_value);
2833 ++_failures;
2834 }
2835 if (!r->isHumongous()) {
2836 _sh_region = NULL;
2837 } else if (r->startsHumongous()) {
2838 _sh_region = r;
2839 } else if (r->continuesHumongous()) {
2840 if (r->humongous_start_region() != _sh_region) {
2841 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2842 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2843 HR_FORMAT_PARAMS(r),
2844 r->humongous_start_region(),
2845 _sh_region);
2846 ++_failures;
2847 }
2848 }
2849 return false;
2850 }
2851 uint failures() { return _failures; }
2852 };
2853
2854 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2855 CheckClaimValuesClosure cl(claim_value);
2856 heap_region_iterate(&cl);
2857 return cl.failures() == 0;
2858 }
2859
2860 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2861 private:
2862 jint _claim_value;
2863 uint _failures;
2864
2865 public:
2866 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2867 _claim_value(claim_value), _failures(0) { }
2868
2869 uint failures() { return _failures; }
2870
2871 bool doHeapRegion(HeapRegion* hr) {
2872 assert(hr->in_collection_set(), "how?");
2873 assert(!hr->isHumongous(), "H-region in CSet");
2874 if (hr->claim_value() != _claim_value) {
2875 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2876 "claim value = %d, should be %d",
2877 HR_FORMAT_PARAMS(hr),
2878 hr->claim_value(), _claim_value);
2879 _failures += 1;
2880 }
2881 return false;
2882 }
2883 };
2884
2885 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2886 CheckClaimValuesInCSetHRClosure cl(claim_value);
2887 collection_set_iterate(&cl);
2888 return cl.failures() == 0;
2889 }
2890 #endif // ASSERT
2891
2892 // Clear the cached CSet starting regions and (more importantly)
2893 // the time stamps. Called when we reset the GC time stamp.
2894 void G1CollectedHeap::clear_cset_start_regions() {
2895 assert(_worker_cset_start_region != NULL, "sanity");
2896 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2897
2898 int n_queues = MAX2((int)ParallelGCThreads, 1);
2899 for (int i = 0; i < n_queues; i++) {
2900 _worker_cset_start_region[i] = NULL;
2901 _worker_cset_start_region_time_stamp[i] = 0;
2902 }
2903 }
2904
2905 // Given the id of a worker, obtain or calculate a suitable
2906 // starting region for iterating over the current collection set.
2907 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2908 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2909
2910 HeapRegion* result = NULL;
2911 unsigned gc_time_stamp = get_gc_time_stamp();
2912
2913 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2914 // Cached starting region for current worker was set
2915 // during the current pause - so it's valid.
2916 // Note: the cached starting heap region may be NULL
2917 // (when the collection set is empty).
2918 result = _worker_cset_start_region[worker_i];
2919 assert(result == NULL || result->in_collection_set(), "sanity");
2920 return result;
2921 }
2922
2923 // The cached entry was not valid so let's calculate
2924 // a suitable starting heap region for this worker.
2925
2926 // We want the parallel threads to start their collection
2927 // set iteration at different collection set regions to
2928 // avoid contention.
2929 // If we have:
2930 // n collection set regions
2931 // p threads
2932 // Then thread t will start at region floor ((t * n) / p)
2933
2934 result = g1_policy()->collection_set();
2935 if (G1CollectedHeap::use_parallel_gc_threads()) {
2936 uint cs_size = g1_policy()->cset_region_length();
2937 uint active_workers = workers()->active_workers();
2938 assert(UseDynamicNumberOfGCThreads ||
2939 active_workers == workers()->total_workers(),
2940 "Unless dynamic should use total workers");
2941
2942 uint end_ind = (cs_size * worker_i) / active_workers;
2943 uint start_ind = 0;
2944
2945 if (worker_i > 0 &&
2946 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2947 // Previous workers starting region is valid
2948 // so let's iterate from there
2949 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2950 result = _worker_cset_start_region[worker_i - 1];
2951 }
2952
2953 for (uint i = start_ind; i < end_ind; i++) {
2954 result = result->next_in_collection_set();
2955 }
2956 }
2957
2958 // Note: the calculated starting heap region may be NULL
2959 // (when the collection set is empty).
2960 assert(result == NULL || result->in_collection_set(), "sanity");
2961 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2962 "should be updated only once per pause");
2963 _worker_cset_start_region[worker_i] = result;
2964 OrderAccess::storestore();
2965 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2966 return result;
2967 }
2968
2969 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2970 uint no_of_par_workers) {
2971 uint worker_num =
2972 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2973 assert(UseDynamicNumberOfGCThreads ||
2974 no_of_par_workers == workers()->total_workers(),
2975 "Non dynamic should use fixed number of workers");
2976 const uint start_index = n_regions() * worker_i / worker_num;
2977 return region_at(start_index);
2978 }
2979
2980 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2981 HeapRegion* r = g1_policy()->collection_set();
2982 while (r != NULL) {
2983 HeapRegion* next = r->next_in_collection_set();
2984 if (cl->doHeapRegion(r)) {
2985 cl->incomplete();
2986 return;
2987 }
2988 r = next;
2989 }
2990 }
2991
2992 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2993 HeapRegionClosure *cl) {
2994 if (r == NULL) {
2995 // The CSet is empty so there's nothing to do.
2996 return;
2997 }
2998
2999 assert(r->in_collection_set(),
3000 "Start region must be a member of the collection set.");
3001 HeapRegion* cur = r;
3002 while (cur != NULL) {
3003 HeapRegion* next = cur->next_in_collection_set();
3004 if (cl->doHeapRegion(cur) && false) {
3005 cl->incomplete();
3006 return;
3007 }
3008 cur = next;
3009 }
3010 cur = g1_policy()->collection_set();
3011 while (cur != r) {
3012 HeapRegion* next = cur->next_in_collection_set();
3013 if (cl->doHeapRegion(cur) && false) {
3014 cl->incomplete();
3015 return;
3016 }
3017 cur = next;
3018 }
3019 }
3020
3021 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
3022 return n_regions() > 0 ? region_at(0) : NULL;
3023 }
3024
3025
3026 Space* G1CollectedHeap::space_containing(const void* addr) const {
3027 Space* res = heap_region_containing(addr);
3028 if (res == NULL)
3029 res = perm_gen()->space_containing(addr);
3030 return res;
3031 }
3032
3033 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
3034 Space* sp = space_containing(addr);
3035 if (sp != NULL) {
3036 return sp->block_start(addr);
3037 }
3038 return NULL;
3039 }
3040
3041 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3042 Space* sp = space_containing(addr);
3043 assert(sp != NULL, "block_size of address outside of heap");
3044 return sp->block_size(addr);
3045 }
3046
3047 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3048 Space* sp = space_containing(addr);
3049 return sp->block_is_obj(addr);
3050 }
3051
3052 bool G1CollectedHeap::supports_tlab_allocation() const {
3053 return true;
3054 }
3055
3056 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3057 return HeapRegion::GrainBytes;
3058 }
3059
3060 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3061 // Return the remaining space in the cur alloc region, but not less than
3062 // the min TLAB size.
3063
3064 // Also, this value can be at most the humongous object threshold,
3065 // since we can't allow tlabs to grow big enough to accommodate
3066 // humongous objects.
3067
3068 HeapRegion* hr = _mutator_alloc_region.get();
3069 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3070 if (hr == NULL) {
3071 return max_tlab_size;
3072 } else {
3073 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3074 }
3075 }
3076
3077 size_t G1CollectedHeap::max_capacity() const {
3078 return _g1_reserved.byte_size();
3079 }
3080
3081 jlong G1CollectedHeap::millis_since_last_gc() {
3082 // assert(false, "NYI");
3083 return 0;
3084 }
3085
3086 void G1CollectedHeap::prepare_for_verify() {
3087 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3088 ensure_parsability(false);
3089 }
3090 g1_rem_set()->prepare_for_verify();
3091 }
3092
3093 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3094 VerifyOption vo) {
3095 switch (vo) {
3096 case VerifyOption_G1UsePrevMarking:
3097 return hr->obj_allocated_since_prev_marking(obj);
3098 case VerifyOption_G1UseNextMarking:
3099 return hr->obj_allocated_since_next_marking(obj);
3100 case VerifyOption_G1UseMarkWord:
3101 return false;
3102 default:
3103 ShouldNotReachHere();
3104 }
3105 return false; // keep some compilers happy
3106 }
3107
3108 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3109 switch (vo) {
3110 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3111 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3112 case VerifyOption_G1UseMarkWord: return NULL;
3113 default: ShouldNotReachHere();
3114 }
3115 return NULL; // keep some compilers happy
3116 }
3117
3118 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3119 switch (vo) {
3120 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3121 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3122 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3123 default: ShouldNotReachHere();
3124 }
3125 return false; // keep some compilers happy
3126 }
3127
3128 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3129 switch (vo) {
3130 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3131 case VerifyOption_G1UseNextMarking: return "NTAMS";
3132 case VerifyOption_G1UseMarkWord: return "NONE";
3133 default: ShouldNotReachHere();
3134 }
3135 return NULL; // keep some compilers happy
3136 }
3137
3138 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3139 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3140 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3141 // we can change this closure to extend the simpler OopClosure.
3142 class VerifyRootsClosure: public OopsInGenClosure {
3143 private:
3144 G1CollectedHeap* _g1h;
3145 VerifyOption _vo;
3146 bool _failures;
3147 public:
3148 // _vo == UsePrevMarking -> use "prev" marking information,
3149 // _vo == UseNextMarking -> use "next" marking information,
3150 // _vo == UseMarkWord -> use mark word from object header.
3151 VerifyRootsClosure(VerifyOption vo) :
3152 _g1h(G1CollectedHeap::heap()),
3153 _vo(vo),
3154 _failures(false) { }
3155
3156 bool failures() { return _failures; }
3157
3158 template <class T> void do_oop_nv(T* p) {
3159 T heap_oop = oopDesc::load_heap_oop(p);
3160 if (!oopDesc::is_null(heap_oop)) {
3161 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3162 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3163 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3164 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3165 if (_vo == VerifyOption_G1UseMarkWord) {
3166 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3167 }
3168 obj->print_on(gclog_or_tty);
3169 _failures = true;
3170 }
3171 }
3172 }
3173
3174 void do_oop(oop* p) { do_oop_nv(p); }
3175 void do_oop(narrowOop* p) { do_oop_nv(p); }
3176 };
3177
3178 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3179 G1CollectedHeap* _g1h;
3180 OopClosure* _root_cl;
3181 nmethod* _nm;
3182 VerifyOption _vo;
3183 bool _failures;
3184
3185 template <class T> void do_oop_work(T* p) {
3186 // First verify that this root is live
3187 _root_cl->do_oop(p);
3188
3189 if (!G1VerifyHeapRegionCodeRoots) {
3190 // We're not verifying the code roots attached to heap region.
3191 return;
3192 }
3193
3194 // Don't check the code roots during marking verification in a full GC
3195 if (_vo == VerifyOption_G1UseMarkWord) {
3196 return;
3197 }
3198
3199 // Now verify that the current nmethod (which contains p) is
3200 // in the code root list of the heap region containing the
3201 // object referenced by p.
3202
3203 T heap_oop = oopDesc::load_heap_oop(p);
3204 if (!oopDesc::is_null(heap_oop)) {
3205 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3206
3207 if (_g1h->is_in_g1_reserved(obj)) {
3208 // Now fetch the region containing the object
3209 HeapRegion* hr = _g1h->heap_region_containing(obj);
3210 HeapRegionRemSet* hrrs = hr->rem_set();
3211 // Verify that the strong code root list for this region
3212 // contains the nmethod
3213 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3214 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3215 "from nmethod "PTR_FORMAT" not in strong "
3216 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3217 p, _nm, hr->bottom(), hr->end());
3218 _failures = true;
3219 }
3220 }
3221 }
3222 }
3223
3224 public:
3225 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3226 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3227
3228 void do_oop(oop* p) { do_oop_work(p); }
3229 void do_oop(narrowOop* p) { do_oop_work(p); }
3230
3231 void set_nmethod(nmethod* nm) { _nm = nm; }
3232 bool failures() { return _failures; }
3233 };
3234
3235 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3236 G1VerifyCodeRootOopClosure* _oop_cl;
3237
3238 public:
3239 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3240 _oop_cl(oop_cl) {}
3241
3242 void do_code_blob(CodeBlob* cb) {
3243 nmethod* nm = cb->as_nmethod_or_null();
3244 if (nm != NULL) {
3245 _oop_cl->set_nmethod(nm);
3246 nm->oops_do(_oop_cl);
3247 }
3248 }
3249 };
3250
3251 class VerifyLivenessOopClosure: public OopClosure {
3252 G1CollectedHeap* _g1h;
3253 VerifyOption _vo;
3254 public:
3255 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3256 _g1h(g1h), _vo(vo)
3257 { }
3258 void do_oop(narrowOop *p) { do_oop_work(p); }
3259 void do_oop( oop *p) { do_oop_work(p); }
3260
3261 template <class T> void do_oop_work(T *p) {
3262 oop obj = oopDesc::load_decode_heap_oop(p);
3263 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3264 "Dead object referenced by a not dead object");
3265 }
3266 };
3267
3268 class VerifyObjsInRegionClosure: public ObjectClosure {
3269 private:
3270 G1CollectedHeap* _g1h;
3271 size_t _live_bytes;
3272 HeapRegion *_hr;
3273 VerifyOption _vo;
3274 public:
3275 // _vo == UsePrevMarking -> use "prev" marking information,
3276 // _vo == UseNextMarking -> use "next" marking information,
3277 // _vo == UseMarkWord -> use mark word from object header.
3278 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3279 : _live_bytes(0), _hr(hr), _vo(vo) {
3280 _g1h = G1CollectedHeap::heap();
3281 }
3282 void do_object(oop o) {
3283 VerifyLivenessOopClosure isLive(_g1h, _vo);
3284 assert(o != NULL, "Huh?");
3285 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3286 // If the object is alive according to the mark word,
3287 // then verify that the marking information agrees.
3288 // Note we can't verify the contra-positive of the
3289 // above: if the object is dead (according to the mark
3290 // word), it may not be marked, or may have been marked
3291 // but has since became dead, or may have been allocated
3292 // since the last marking.
3293 if (_vo == VerifyOption_G1UseMarkWord) {
3294 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3295 }
3296
3297 o->oop_iterate(&isLive);
3298 if (!_hr->obj_allocated_since_prev_marking(o)) {
3299 size_t obj_size = o->size(); // Make sure we don't overflow
3300 _live_bytes += (obj_size * HeapWordSize);
3301 }
3302 }
3303 }
3304 size_t live_bytes() { return _live_bytes; }
3305 };
3306
3307 class PrintObjsInRegionClosure : public ObjectClosure {
3308 HeapRegion *_hr;
3309 G1CollectedHeap *_g1;
3310 public:
3311 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3312 _g1 = G1CollectedHeap::heap();
3313 };
3314
3315 void do_object(oop o) {
3316 if (o != NULL) {
3317 HeapWord *start = (HeapWord *) o;
3318 size_t word_sz = o->size();
3319 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3320 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3321 (void*) o, word_sz,
3322 _g1->isMarkedPrev(o),
3323 _g1->isMarkedNext(o),
3324 _hr->obj_allocated_since_prev_marking(o));
3325 HeapWord *end = start + word_sz;
3326 HeapWord *cur;
3327 int *val;
3328 for (cur = start; cur < end; cur++) {
3329 val = (int *) cur;
3330 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3331 }
3332 }
3333 }
3334 };
3335
3336 class VerifyRegionClosure: public HeapRegionClosure {
3337 private:
3338 bool _par;
3339 VerifyOption _vo;
3340 bool _failures;
3341 public:
3342 // _vo == UsePrevMarking -> use "prev" marking information,
3343 // _vo == UseNextMarking -> use "next" marking information,
3344 // _vo == UseMarkWord -> use mark word from object header.
3345 VerifyRegionClosure(bool par, VerifyOption vo)
3346 : _par(par),
3347 _vo(vo),
3348 _failures(false) {}
3349
3350 bool failures() {
3351 return _failures;
3352 }
3353
3354 bool doHeapRegion(HeapRegion* r) {
3355 if (!r->continuesHumongous()) {
3356 bool failures = false;
3357 r->verify(_vo, &failures);
3358 if (failures) {
3359 _failures = true;
3360 } else {
3361 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3362 r->object_iterate(¬_dead_yet_cl);
3363 if (_vo != VerifyOption_G1UseNextMarking) {
3364 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3365 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3366 "max_live_bytes "SIZE_FORMAT" "
3367 "< calculated "SIZE_FORMAT,
3368 r->bottom(), r->end(),
3369 r->max_live_bytes(),
3370 not_dead_yet_cl.live_bytes());
3371 _failures = true;
3372 }
3373 } else {
3374 // When vo == UseNextMarking we cannot currently do a sanity
3375 // check on the live bytes as the calculation has not been
3376 // finalized yet.
3377 }
3378 }
3379 }
3380 return false; // stop the region iteration if we hit a failure
3381 }
3382 };
3383
3384 // This is the task used for parallel heap verification.
3385
3386 class G1ParVerifyTask: public AbstractGangTask {
3387 private:
3388 G1CollectedHeap* _g1h;
3389 VerifyOption _vo;
3390 bool _failures;
3391
3392 public:
3393 // _vo == UsePrevMarking -> use "prev" marking information,
3394 // _vo == UseNextMarking -> use "next" marking information,
3395 // _vo == UseMarkWord -> use mark word from object header.
3396 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3397 AbstractGangTask("Parallel verify task"),
3398 _g1h(g1h),
3399 _vo(vo),
3400 _failures(false) { }
3401
3402 bool failures() {
3403 return _failures;
3404 }
3405
3406 void work(uint worker_id) {
3407 HandleMark hm;
3408 VerifyRegionClosure blk(true, _vo);
3409 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3410 _g1h->workers()->active_workers(),
3411 HeapRegion::ParVerifyClaimValue);
3412 if (blk.failures()) {
3413 _failures = true;
3414 }
3415 }
3416 };
3417
3418 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3419 if (SafepointSynchronize::is_at_safepoint()) {
3420 assert(Thread::current()->is_VM_thread(),
3421 "Expected to be executed serially by the VM thread at this point");
3422
3423 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3424 VerifyRootsClosure rootsCl(vo);
3425
3426 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3427 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3428 // We apply the relevant closures to all the oops in the
3429 // system dictionary, the string table and the code cache.
3430 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3431
3432 process_strong_roots(true, // activate StrongRootsScope
3433 true, // we set "collecting perm gen" to true,
3434 // so we don't reset the dirty cards in the perm gen.
3435 ScanningOption(so), // roots scanning options
3436 &rootsCl,
3437 &blobsCl,
3438 &rootsCl);
3439
3440 // If we're verifying after the marking phase of a Full GC then we can't
3441 // treat the perm gen as roots into the G1 heap. Some of the objects in
3442 // the perm gen may be dead and hence not marked. If one of these dead
3443 // objects is considered to be a root then we may end up with a false
3444 // "Root location <x> points to dead ob <y>" failure.
3445 if (vo != VerifyOption_G1UseMarkWord) {
3446 // Since we used "collecting_perm_gen" == true above, we will not have
3447 // checked the refs from perm into the G1-collected heap. We check those
3448 // references explicitly below. Whether the relevant cards are dirty
3449 // is checked further below in the rem set verification.
3450 if (!silent) { gclog_or_tty->print("Permgen roots "); }
3451 perm_gen()->oop_iterate(&rootsCl);
3452 }
3453 bool failures = rootsCl.failures();
3454
3455 if (vo != VerifyOption_G1UseMarkWord) {
3456 // If we're verifying during a full GC then the region sets
3457 // will have been torn down at the start of the GC. Therefore
3458 // verifying the region sets will fail. So we only verify
3459 // the region sets when not in a full GC.
3460 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3461 verify_region_sets();
3462 }
3463
3464 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3465 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3466 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3467 "sanity check");
3468
3469 G1ParVerifyTask task(this, vo);
3470 assert(UseDynamicNumberOfGCThreads ||
3471 workers()->active_workers() == workers()->total_workers(),
3472 "If not dynamic should be using all the workers");
3473 int n_workers = workers()->active_workers();
3474 set_par_threads(n_workers);
3475 workers()->run_task(&task);
3476 set_par_threads(0);
3477 if (task.failures()) {
3478 failures = true;
3479 }
3480
3481 // Checks that the expected amount of parallel work was done.
3482 // The implication is that n_workers is > 0.
3483 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3484 "sanity check");
3485
3486 reset_heap_region_claim_values();
3487
3488 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3489 "sanity check");
3490 } else {
3491 VerifyRegionClosure blk(false, vo);
3492 heap_region_iterate(&blk);
3493 if (blk.failures()) {
3494 failures = true;
3495 }
3496 }
3497 if (!silent) gclog_or_tty->print("RemSet ");
3498 rem_set()->verify();
3499
3500 if (failures) {
3501 gclog_or_tty->print_cr("Heap:");
3502 // It helps to have the per-region information in the output to
3503 // help us track down what went wrong. This is why we call
3504 // print_extended_on() instead of print_on().
3505 print_extended_on(gclog_or_tty);
3506 gclog_or_tty->print_cr("");
3507 #ifndef PRODUCT
3508 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3509 concurrent_mark()->print_reachable("at-verification-failure",
3510 vo, false /* all */);
3511 }
3512 #endif
3513 gclog_or_tty->flush();
3514 }
3515 guarantee(!failures, "there should not have been any failures");
3516 } else {
3517 if (!silent)
3518 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3519 }
3520 }
3521
3522 void G1CollectedHeap::verify(bool silent) {
3523 verify(silent, VerifyOption_G1UsePrevMarking);
3524 }
3525
3526 double G1CollectedHeap::verify(bool guard, const char* msg) {
3527 double verify_time_ms = 0.0;
3528
3529 if (guard && total_collections() >= VerifyGCStartAt) {
3530 double verify_start = os::elapsedTime();
3531 HandleMark hm; // Discard invalid handles created during verification
3532 prepare_for_verify();
3533 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3534 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3535 }
3536
3537 return verify_time_ms;
3538 }
3539
3540 void G1CollectedHeap::verify_before_gc() {
3541 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3542 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3543 }
3544
3545 void G1CollectedHeap::verify_after_gc() {
3546 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3547 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3548 }
3549
3550 class PrintRegionClosure: public HeapRegionClosure {
3551 outputStream* _st;
3552 public:
3553 PrintRegionClosure(outputStream* st) : _st(st) {}
3554 bool doHeapRegion(HeapRegion* r) {
3555 r->print_on(_st);
3556 return false;
3557 }
3558 };
3559
3560 void G1CollectedHeap::print_on(outputStream* st) const {
3561 st->print(" %-20s", "garbage-first heap");
3562 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3563 capacity()/K, used_unlocked()/K);
3564 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3565 _g1_storage.low_boundary(),
3566 _g1_storage.high(),
3567 _g1_storage.high_boundary());
3568 st->cr();
3569 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3570 uint young_regions = _young_list->length();
3571 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3572 (size_t) young_regions * HeapRegion::GrainBytes / K);
3573 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3574 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3575 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3576 st->cr();
3577 perm()->as_gen()->print_on(st);
3578 }
3579
3580 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3581 print_on(st);
3582
3583 // Print the per-region information.
3584 st->cr();
3585 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3586 "HS=humongous(starts), HC=humongous(continues), "
3587 "CS=collection set, F=free, TS=gc time stamp, "
3588 "PTAMS=previous top-at-mark-start, "
3589 "NTAMS=next top-at-mark-start)");
3590 PrintRegionClosure blk(st);
3591 heap_region_iterate(&blk);
3592 }
3593
3594 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3595 if (G1CollectedHeap::use_parallel_gc_threads()) {
3596 workers()->print_worker_threads_on(st);
3597 }
3598 _cmThread->print_on(st);
3599 st->cr();
3600 _cm->print_worker_threads_on(st);
3601 _cg1r->print_worker_threads_on(st);
3602 st->cr();
3603 }
3604
3605 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3606 if (G1CollectedHeap::use_parallel_gc_threads()) {
3607 workers()->threads_do(tc);
3608 }
3609 tc->do_thread(_cmThread);
3610 _cg1r->threads_do(tc);
3611 }
3612
3613 void G1CollectedHeap::print_tracing_info() const {
3614 // We'll overload this to mean "trace GC pause statistics."
3615 if (TraceGen0Time || TraceGen1Time) {
3616 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3617 // to that.
3618 g1_policy()->print_tracing_info();
3619 }
3620 if (G1SummarizeRSetStats) {
3621 g1_rem_set()->print_summary_info();
3622 }
3623 if (G1SummarizeConcMark) {
3624 concurrent_mark()->print_summary_info();
3625 }
3626 g1_policy()->print_yg_surv_rate_info();
3627 SpecializationStats::print();
3628 }
3629
3630 #ifndef PRODUCT
3631 // Helpful for debugging RSet issues.
3632
3633 class PrintRSetsClosure : public HeapRegionClosure {
3634 private:
3635 const char* _msg;
3636 size_t _occupied_sum;
3637
3638 public:
3639 bool doHeapRegion(HeapRegion* r) {
3640 HeapRegionRemSet* hrrs = r->rem_set();
3641 size_t occupied = hrrs->occupied();
3642 _occupied_sum += occupied;
3643
3644 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3645 HR_FORMAT_PARAMS(r));
3646 if (occupied == 0) {
3647 gclog_or_tty->print_cr(" RSet is empty");
3648 } else {
3649 hrrs->print();
3650 }
3651 gclog_or_tty->print_cr("----------");
3652 return false;
3653 }
3654
3655 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3656 gclog_or_tty->cr();
3657 gclog_or_tty->print_cr("========================================");
3658 gclog_or_tty->print_cr(msg);
3659 gclog_or_tty->cr();
3660 }
3661
3662 ~PrintRSetsClosure() {
3663 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3664 gclog_or_tty->print_cr("========================================");
3665 gclog_or_tty->cr();
3666 }
3667 };
3668
3669 void G1CollectedHeap::print_cset_rsets() {
3670 PrintRSetsClosure cl("Printing CSet RSets");
3671 collection_set_iterate(&cl);
3672 }
3673
3674 void G1CollectedHeap::print_all_rsets() {
3675 PrintRSetsClosure cl("Printing All RSets");;
3676 heap_region_iterate(&cl);
3677 }
3678 #endif // PRODUCT
3679
3680 G1CollectedHeap* G1CollectedHeap::heap() {
3681 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3682 "not a garbage-first heap");
3683 return _g1h;
3684 }
3685
3686 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3687 // always_do_update_barrier = false;
3688 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3689 // Call allocation profiler
3690 AllocationProfiler::iterate_since_last_gc();
3691 // Fill TLAB's and such
3692 ensure_parsability(true);
3693
3694 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3695 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3696 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3697 }
3698 }
3699
3700 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3701
3702 if (G1SummarizeRSetStats &&
3703 (G1SummarizeRSetStatsPeriod > 0) &&
3704 // we are at the end of the GC. Total collections has already been increased.
3705 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3706 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3707 }
3708
3709 // FIXME: what is this about?
3710 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3711 // is set.
3712 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3713 "derived pointer present"));
3714 // always_do_update_barrier = true;
3715
3716 // We have just completed a GC. Update the soft reference
3717 // policy with the new heap occupancy
3718 Universe::update_heap_info_at_gc();
3719 }
3720
3721 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3722 unsigned int gc_count_before,
3723 bool* succeeded) {
3724 assert_heap_not_locked_and_not_at_safepoint();
3725 g1_policy()->record_stop_world_start();
3726 VM_G1IncCollectionPause op(gc_count_before,
3727 word_size,
3728 false, /* should_initiate_conc_mark */
3729 g1_policy()->max_pause_time_ms(),
3730 GCCause::_g1_inc_collection_pause);
3731 VMThread::execute(&op);
3732
3733 HeapWord* result = op.result();
3734 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3735 assert(result == NULL || ret_succeeded,
3736 "the result should be NULL if the VM did not succeed");
3737 *succeeded = ret_succeeded;
3738
3739 assert_heap_not_locked();
3740 return result;
3741 }
3742
3743 void
3744 G1CollectedHeap::doConcurrentMark() {
3745 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3746 if (!_cmThread->in_progress()) {
3747 _cmThread->set_started();
3748 CGC_lock->notify();
3749 }
3750 }
3751
3752 size_t G1CollectedHeap::pending_card_num() {
3753 size_t extra_cards = 0;
3754 JavaThread *curr = Threads::first();
3755 while (curr != NULL) {
3756 DirtyCardQueue& dcq = curr->dirty_card_queue();
3757 extra_cards += dcq.size();
3758 curr = curr->next();
3759 }
3760 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3761 size_t buffer_size = dcqs.buffer_size();
3762 size_t buffer_num = dcqs.completed_buffers_num();
3763
3764 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3765 // in bytes - not the number of 'entries'. We need to convert
3766 // into a number of cards.
3767 return (buffer_size * buffer_num + extra_cards) / oopSize;
3768 }
3769
3770 size_t G1CollectedHeap::cards_scanned() {
3771 return g1_rem_set()->cardsScanned();
3772 }
3773
3774 void
3775 G1CollectedHeap::setup_surviving_young_words() {
3776 assert(_surviving_young_words == NULL, "pre-condition");
3777 uint array_length = g1_policy()->young_cset_region_length();
3778 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3779 if (_surviving_young_words == NULL) {
3780 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3781 "Not enough space for young surv words summary.");
3782 }
3783 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3784 #ifdef ASSERT
3785 for (uint i = 0; i < array_length; ++i) {
3786 assert( _surviving_young_words[i] == 0, "memset above" );
3787 }
3788 #endif // !ASSERT
3789 }
3790
3791 void
3792 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3793 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3794 uint array_length = g1_policy()->young_cset_region_length();
3795 for (uint i = 0; i < array_length; ++i) {
3796 _surviving_young_words[i] += surv_young_words[i];
3797 }
3798 }
3799
3800 void
3801 G1CollectedHeap::cleanup_surviving_young_words() {
3802 guarantee( _surviving_young_words != NULL, "pre-condition" );
3803 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3804 _surviving_young_words = NULL;
3805 }
3806
3807 #ifdef ASSERT
3808 class VerifyCSetClosure: public HeapRegionClosure {
3809 public:
3810 bool doHeapRegion(HeapRegion* hr) {
3811 // Here we check that the CSet region's RSet is ready for parallel
3812 // iteration. The fields that we'll verify are only manipulated
3813 // when the region is part of a CSet and is collected. Afterwards,
3814 // we reset these fields when we clear the region's RSet (when the
3815 // region is freed) so they are ready when the region is
3816 // re-allocated. The only exception to this is if there's an
3817 // evacuation failure and instead of freeing the region we leave
3818 // it in the heap. In that case, we reset these fields during
3819 // evacuation failure handling.
3820 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3821
3822 // Here's a good place to add any other checks we'd like to
3823 // perform on CSet regions.
3824 return false;
3825 }
3826 };
3827 #endif // ASSERT
3828
3829 #if TASKQUEUE_STATS
3830 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3831 st->print_raw_cr("GC Task Stats");
3832 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3833 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3834 }
3835
3836 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3837 print_taskqueue_stats_hdr(st);
3838
3839 TaskQueueStats totals;
3840 const int n = workers() != NULL ? workers()->total_workers() : 1;
3841 for (int i = 0; i < n; ++i) {
3842 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3843 totals += task_queue(i)->stats;
3844 }
3845 st->print_raw("tot "); totals.print(st); st->cr();
3846
3847 DEBUG_ONLY(totals.verify());
3848 }
3849
3850 void G1CollectedHeap::reset_taskqueue_stats() {
3851 const int n = workers() != NULL ? workers()->total_workers() : 1;
3852 for (int i = 0; i < n; ++i) {
3853 task_queue(i)->stats.reset();
3854 }
3855 }
3856 #endif // TASKQUEUE_STATS
3857
3858 void G1CollectedHeap::log_gc_header() {
3859 if (!G1Log::fine()) {
3860 return;
3861 }
3862
3863 gclog_or_tty->date_stamp(PrintGCDateStamps);
3864 gclog_or_tty->stamp(PrintGCTimeStamps);
3865
3866 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3867 .append(g1_policy()->gcs_are_young() ? " (young)" : " (mixed)")
3868 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3869
3870 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3871 }
3872
3873 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3874 if (!G1Log::fine()) {
3875 return;
3876 }
3877
3878 if (G1Log::finer()) {
3879 if (evacuation_failed()) {
3880 gclog_or_tty->print(" (to-space exhausted)");
3881 }
3882 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3883 g1_policy()->phase_times()->note_gc_end();
3884 g1_policy()->phase_times()->print(pause_time_sec);
3885 g1_policy()->print_detailed_heap_transition();
3886 } else {
3887 if (evacuation_failed()) {
3888 gclog_or_tty->print("--");
3889 }
3890 g1_policy()->print_heap_transition();
3891 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3892 }
3893 gclog_or_tty->flush();
3894 }
3895
3896 bool
3897 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3898 assert_at_safepoint(true /* should_be_vm_thread */);
3899 guarantee(!is_gc_active(), "collection is not reentrant");
3900
3901 if (GC_locker::check_active_before_gc()) {
3902 return false;
3903 }
3904
3905 _gc_timer_stw->register_gc_start();
3906
3907 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3908
3909 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3910 ResourceMark rm;
3911
3912 print_heap_before_gc();
3913 trace_heap_before_gc(_gc_tracer_stw);
3914
3915 HRSPhaseSetter x(HRSPhaseEvacuation);
3916 verify_region_sets_optional();
3917 verify_dirty_young_regions();
3918
3919 // This call will decide whether this pause is an initial-mark
3920 // pause. If it is, during_initial_mark_pause() will return true
3921 // for the duration of this pause.
3922 g1_policy()->decide_on_conc_mark_initiation();
3923
3924 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3925 assert(!g1_policy()->during_initial_mark_pause() ||
3926 g1_policy()->gcs_are_young(), "sanity");
3927
3928 // We also do not allow mixed GCs during marking.
3929 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3930
3931 // Record whether this pause is an initial mark. When the current
3932 // thread has completed its logging output and it's safe to signal
3933 // the CM thread, the flag's value in the policy has been reset.
3934 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3935
3936 // Inner scope for scope based logging, timers, and stats collection
3937 {
3938 EvacuationInfo evacuation_info;
3939
3940 if (g1_policy()->during_initial_mark_pause()) {
3941 // We are about to start a marking cycle, so we increment the
3942 // full collection counter.
3943 increment_old_marking_cycles_started();
3944 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3945 }
3946
3947 _gc_tracer_stw->report_yc_type(yc_type());
3948
3949 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3950
3951 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3952 workers()->active_workers() : 1);
3953 double pause_start_sec = os::elapsedTime();
3954 g1_policy()->phase_times()->note_gc_start(active_workers);
3955 log_gc_header();
3956
3957 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3958 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3959
3960 // If the secondary_free_list is not empty, append it to the
3961 // free_list. No need to wait for the cleanup operation to finish;
3962 // the region allocation code will check the secondary_free_list
3963 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3964 // set, skip this step so that the region allocation code has to
3965 // get entries from the secondary_free_list.
3966 if (!G1StressConcRegionFreeing) {
3967 append_secondary_free_list_if_not_empty_with_lock();
3968 }
3969
3970 assert(check_young_list_well_formed(), "young list should be well formed");
3971 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3972 "sanity check");
3973
3974 // Don't dynamically change the number of GC threads this early. A value of
3975 // 0 is used to indicate serial work. When parallel work is done,
3976 // it will be set.
3977
3978 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3979 IsGCActiveMark x;
3980
3981 gc_prologue(false);
3982 increment_total_collections(false /* full gc */);
3983 increment_gc_time_stamp();
3984
3985 verify_before_gc();
3986
3987 COMPILER2_PRESENT(DerivedPointerTable::clear());
3988
3989 // Please see comment in g1CollectedHeap.hpp and
3990 // G1CollectedHeap::ref_processing_init() to see how
3991 // reference processing currently works in G1.
3992
3993 // Enable discovery in the STW reference processor
3994 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3995 true /*verify_no_refs*/);
3996
3997 {
3998 // We want to temporarily turn off discovery by the
3999 // CM ref processor, if necessary, and turn it back on
4000 // on again later if we do. Using a scoped
4001 // NoRefDiscovery object will do this.
4002 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4003
4004 // Forget the current alloc region (we might even choose it to be part
4005 // of the collection set!).
4006 release_mutator_alloc_region();
4007
4008 // We should call this after we retire the mutator alloc
4009 // region(s) so that all the ALLOC / RETIRE events are generated
4010 // before the start GC event.
4011 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4012
4013 // This timing is only used by the ergonomics to handle our pause target.
4014 // It is unclear why this should not include the full pause. We will
4015 // investigate this in CR 7178365.
4016 //
4017 // Preserving the old comment here if that helps the investigation:
4018 //
4019 // The elapsed time induced by the start time below deliberately elides
4020 // the possible verification above.
4021 double sample_start_time_sec = os::elapsedTime();
4022
4023 #if YOUNG_LIST_VERBOSE
4024 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4025 _young_list->print();
4026 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4027 #endif // YOUNG_LIST_VERBOSE
4028
4029 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4030
4031 double scan_wait_start = os::elapsedTime();
4032 // We have to wait until the CM threads finish scanning the
4033 // root regions as it's the only way to ensure that all the
4034 // objects on them have been correctly scanned before we start
4035 // moving them during the GC.
4036 bool waited = _cm->root_regions()->wait_until_scan_finished();
4037 double wait_time_ms = 0.0;
4038 if (waited) {
4039 double scan_wait_end = os::elapsedTime();
4040 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4041 }
4042 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4043
4044 #if YOUNG_LIST_VERBOSE
4045 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4046 _young_list->print();
4047 #endif // YOUNG_LIST_VERBOSE
4048
4049 if (g1_policy()->during_initial_mark_pause()) {
4050 concurrent_mark()->checkpointRootsInitialPre();
4051 }
4052 perm_gen()->save_marks();
4053
4054 #if YOUNG_LIST_VERBOSE
4055 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4056 _young_list->print();
4057 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4058 #endif // YOUNG_LIST_VERBOSE
4059
4060 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4061
4062 _cm->note_start_of_gc();
4063 // We should not verify the per-thread SATB buffers given that
4064 // we have not filtered them yet (we'll do so during the
4065 // GC). We also call this after finalize_cset() to
4066 // ensure that the CSet has been finalized.
4067 _cm->verify_no_cset_oops(true /* verify_stacks */,
4068 true /* verify_enqueued_buffers */,
4069 false /* verify_thread_buffers */,
4070 true /* verify_fingers */);
4071
4072 if (_hr_printer.is_active()) {
4073 HeapRegion* hr = g1_policy()->collection_set();
4074 while (hr != NULL) {
4075 G1HRPrinter::RegionType type;
4076 if (!hr->is_young()) {
4077 type = G1HRPrinter::Old;
4078 } else if (hr->is_survivor()) {
4079 type = G1HRPrinter::Survivor;
4080 } else {
4081 type = G1HRPrinter::Eden;
4082 }
4083 _hr_printer.cset(hr);
4084 hr = hr->next_in_collection_set();
4085 }
4086 }
4087
4088 #ifdef ASSERT
4089 VerifyCSetClosure cl;
4090 collection_set_iterate(&cl);
4091 #endif // ASSERT
4092
4093 setup_surviving_young_words();
4094
4095 // Initialize the GC alloc regions.
4096 init_gc_alloc_regions(evacuation_info);
4097
4098 // Actually do the work...
4099 evacuate_collection_set(evacuation_info);
4100
4101 // We do this to mainly verify the per-thread SATB buffers
4102 // (which have been filtered by now) since we didn't verify
4103 // them earlier. No point in re-checking the stacks / enqueued
4104 // buffers given that the CSet has not changed since last time
4105 // we checked.
4106 _cm->verify_no_cset_oops(false /* verify_stacks */,
4107 false /* verify_enqueued_buffers */,
4108 true /* verify_thread_buffers */,
4109 true /* verify_fingers */);
4110
4111 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4112 g1_policy()->clear_collection_set();
4113
4114 cleanup_surviving_young_words();
4115
4116 // Start a new incremental collection set for the next pause.
4117 g1_policy()->start_incremental_cset_building();
4118
4119 // Clear the _cset_fast_test bitmap in anticipation of adding
4120 // regions to the incremental collection set for the next
4121 // evacuation pause.
4122 clear_cset_fast_test();
4123
4124 _young_list->reset_sampled_info();
4125
4126 // Don't check the whole heap at this point as the
4127 // GC alloc regions from this pause have been tagged
4128 // as survivors and moved on to the survivor list.
4129 // Survivor regions will fail the !is_young() check.
4130 assert(check_young_list_empty(false /* check_heap */),
4131 "young list should be empty");
4132
4133 #if YOUNG_LIST_VERBOSE
4134 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4135 _young_list->print();
4136 #endif // YOUNG_LIST_VERBOSE
4137
4138 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4139 _young_list->first_survivor_region(),
4140 _young_list->last_survivor_region());
4141
4142 _young_list->reset_auxilary_lists();
4143
4144 if (evacuation_failed()) {
4145 _summary_bytes_used = recalculate_used();
4146 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4147 for (uint i = 0; i < n_queues; i++) {
4148 if (_evacuation_failed_info_array[i].has_failed()) {
4149 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4150 }
4151 }
4152 } else {
4153 // The "used" of the the collection set have already been subtracted
4154 // when they were freed. Add in the bytes evacuated.
4155 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4156 }
4157
4158 if (g1_policy()->during_initial_mark_pause()) {
4159 // We have to do this before we notify the CM threads that
4160 // they can start working to make sure that all the
4161 // appropriate initialization is done on the CM object.
4162 concurrent_mark()->checkpointRootsInitialPost();
4163 set_marking_started();
4164 // Note that we don't actually trigger the CM thread at
4165 // this point. We do that later when we're sure that
4166 // the current thread has completed its logging output.
4167 }
4168
4169 allocate_dummy_regions();
4170
4171 #if YOUNG_LIST_VERBOSE
4172 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4173 _young_list->print();
4174 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4175 #endif // YOUNG_LIST_VERBOSE
4176
4177 init_mutator_alloc_region();
4178
4179 {
4180 size_t expand_bytes = g1_policy()->expansion_amount();
4181 if (expand_bytes > 0) {
4182 size_t bytes_before = capacity();
4183 // No need for an ergo verbose message here,
4184 // expansion_amount() does this when it returns a value > 0.
4185 if (!expand(expand_bytes)) {
4186 // We failed to expand the heap so let's verify that
4187 // committed/uncommitted amount match the backing store
4188 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4189 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4190 }
4191 }
4192 }
4193
4194 // We redo the verification but now wrt to the new CSet which
4195 // has just got initialized after the previous CSet was freed.
4196 _cm->verify_no_cset_oops(true /* verify_stacks */,
4197 true /* verify_enqueued_buffers */,
4198 true /* verify_thread_buffers */,
4199 true /* verify_fingers */);
4200 _cm->note_end_of_gc();
4201
4202 // This timing is only used by the ergonomics to handle our pause target.
4203 // It is unclear why this should not include the full pause. We will
4204 // investigate this in CR 7178365.
4205 double sample_end_time_sec = os::elapsedTime();
4206 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4207 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4208
4209 MemoryService::track_memory_usage();
4210
4211 // In prepare_for_verify() below we'll need to scan the deferred
4212 // update buffers to bring the RSets up-to-date if
4213 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4214 // the update buffers we'll probably need to scan cards on the
4215 // regions we just allocated to (i.e., the GC alloc
4216 // regions). However, during the last GC we called
4217 // set_saved_mark() on all the GC alloc regions, so card
4218 // scanning might skip the [saved_mark_word()...top()] area of
4219 // those regions (i.e., the area we allocated objects into
4220 // during the last GC). But it shouldn't. Given that
4221 // saved_mark_word() is conditional on whether the GC time stamp
4222 // on the region is current or not, by incrementing the GC time
4223 // stamp here we invalidate all the GC time stamps on all the
4224 // regions and saved_mark_word() will simply return top() for
4225 // all the regions. This is a nicer way of ensuring this rather
4226 // than iterating over the regions and fixing them. In fact, the
4227 // GC time stamp increment here also ensures that
4228 // saved_mark_word() will return top() between pauses, i.e.,
4229 // during concurrent refinement. So we don't need the
4230 // is_gc_active() check to decided which top to use when
4231 // scanning cards (see CR 7039627).
4232 increment_gc_time_stamp();
4233
4234 verify_after_gc();
4235
4236 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4237 ref_processor_stw()->verify_no_references_recorded();
4238
4239 // CM reference discovery will be re-enabled if necessary.
4240 }
4241
4242 // We should do this after we potentially expand the heap so
4243 // that all the COMMIT events are generated before the end GC
4244 // event, and after we retire the GC alloc regions so that all
4245 // RETIRE events are generated before the end GC event.
4246 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4247
4248 if (mark_in_progress()) {
4249 concurrent_mark()->update_g1_committed();
4250 }
4251
4252 #ifdef TRACESPINNING
4253 ParallelTaskTerminator::print_termination_counts();
4254 #endif
4255
4256 gc_epilogue(false);
4257 }
4258
4259 // Print the remainder of the GC log output.
4260 log_gc_footer(os::elapsedTime() - pause_start_sec);
4261
4262 // It is not yet to safe to tell the concurrent mark to
4263 // start as we have some optional output below. We don't want the
4264 // output from the concurrent mark thread interfering with this
4265 // logging output either.
4266
4267 _hrs.verify_optional();
4268 verify_region_sets_optional();
4269
4270 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4271 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4272
4273 print_heap_after_gc();
4274 trace_heap_after_gc(_gc_tracer_stw);
4275
4276 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4277 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4278 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4279 // before any GC notifications are raised.
4280 g1mm()->update_sizes();
4281
4282 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4283 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4284 _gc_timer_stw->register_gc_end();
4285 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4286 }
4287
4288 // It should now be safe to tell the concurrent mark thread to start
4289 // without its logging output interfering with the logging output
4290 // that came from the pause.
4291
4292 if (should_start_conc_mark) {
4293 // CAUTION: after the doConcurrentMark() call below,
4294 // the concurrent marking thread(s) could be running
4295 // concurrently with us. Make sure that anything after
4296 // this point does not assume that we are the only GC thread
4297 // running. Note: of course, the actual marking work will
4298 // not start until the safepoint itself is released in
4299 // ConcurrentGCThread::safepoint_desynchronize().
4300 doConcurrentMark();
4301 }
4302
4303 return true;
4304 }
4305
4306 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4307 {
4308 size_t gclab_word_size;
4309 switch (purpose) {
4310 case GCAllocForSurvived:
4311 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4312 break;
4313 case GCAllocForTenured:
4314 gclab_word_size = _old_plab_stats.desired_plab_sz();
4315 break;
4316 default:
4317 assert(false, "unknown GCAllocPurpose");
4318 gclab_word_size = _old_plab_stats.desired_plab_sz();
4319 break;
4320 }
4321
4322 // Prevent humongous PLAB sizes for two reasons:
4323 // * PLABs are allocated using a similar paths as oops, but should
4324 // never be in a humongous region
4325 // * Allowing humongous PLABs needlessly churns the region free lists
4326 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4327 }
4328
4329 void G1CollectedHeap::init_mutator_alloc_region() {
4330 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4331 _mutator_alloc_region.init();
4332 }
4333
4334 void G1CollectedHeap::release_mutator_alloc_region() {
4335 _mutator_alloc_region.release();
4336 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4337 }
4338
4339 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4340 assert_at_safepoint(true /* should_be_vm_thread */);
4341
4342 _survivor_gc_alloc_region.init();
4343 _old_gc_alloc_region.init();
4344 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4345 _retained_old_gc_alloc_region = NULL;
4346
4347 // We will discard the current GC alloc region if:
4348 // a) it's in the collection set (it can happen!),
4349 // b) it's already full (no point in using it),
4350 // c) it's empty (this means that it was emptied during
4351 // a cleanup and it should be on the free list now), or
4352 // d) it's humongous (this means that it was emptied
4353 // during a cleanup and was added to the free list, but
4354 // has been subsequently used to allocate a humongous
4355 // object that may be less than the region size).
4356 if (retained_region != NULL &&
4357 !retained_region->in_collection_set() &&
4358 !(retained_region->top() == retained_region->end()) &&
4359 !retained_region->is_empty() &&
4360 !retained_region->isHumongous()) {
4361 retained_region->set_saved_mark();
4362 // The retained region was added to the old region set when it was
4363 // retired. We have to remove it now, since we don't allow regions
4364 // we allocate to in the region sets. We'll re-add it later, when
4365 // it's retired again.
4366 _old_set.remove(retained_region);
4367 bool during_im = g1_policy()->during_initial_mark_pause();
4368 retained_region->note_start_of_copying(during_im);
4369 _old_gc_alloc_region.set(retained_region);
4370 _hr_printer.reuse(retained_region);
4371 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4372 }
4373 }
4374
4375 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4376 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4377 _old_gc_alloc_region.count());
4378 _survivor_gc_alloc_region.release();
4379 // If we have an old GC alloc region to release, we'll save it in
4380 // _retained_old_gc_alloc_region. If we don't
4381 // _retained_old_gc_alloc_region will become NULL. This is what we
4382 // want either way so no reason to check explicitly for either
4383 // condition.
4384 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4385
4386 if (ResizePLAB) {
4387 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4388 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4389 }
4390 }
4391
4392 void G1CollectedHeap::abandon_gc_alloc_regions() {
4393 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4394 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4395 _retained_old_gc_alloc_region = NULL;
4396 }
4397
4398 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4399 _drain_in_progress = false;
4400 set_evac_failure_closure(cl);
4401 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4402 }
4403
4404 void G1CollectedHeap::finalize_for_evac_failure() {
4405 assert(_evac_failure_scan_stack != NULL &&
4406 _evac_failure_scan_stack->length() == 0,
4407 "Postcondition");
4408 assert(!_drain_in_progress, "Postcondition");
4409 delete _evac_failure_scan_stack;
4410 _evac_failure_scan_stack = NULL;
4411 }
4412
4413 void G1CollectedHeap::remove_self_forwarding_pointers() {
4414 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4415
4416 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4417
4418 if (G1CollectedHeap::use_parallel_gc_threads()) {
4419 set_par_threads();
4420 workers()->run_task(&rsfp_task);
4421 set_par_threads(0);
4422 } else {
4423 rsfp_task.work(0);
4424 }
4425
4426 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4427
4428 // Reset the claim values in the regions in the collection set.
4429 reset_cset_heap_region_claim_values();
4430
4431 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4432
4433 // Now restore saved marks, if any.
4434 assert(_objs_with_preserved_marks.size() ==
4435 _preserved_marks_of_objs.size(), "Both or none.");
4436 while (!_objs_with_preserved_marks.is_empty()) {
4437 oop obj = _objs_with_preserved_marks.pop();
4438 markOop m = _preserved_marks_of_objs.pop();
4439 obj->set_mark(m);
4440 }
4441 _objs_with_preserved_marks.clear(true);
4442 _preserved_marks_of_objs.clear(true);
4443 }
4444
4445 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4446 _evac_failure_scan_stack->push(obj);
4447 }
4448
4449 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4450 assert(_evac_failure_scan_stack != NULL, "precondition");
4451
4452 while (_evac_failure_scan_stack->length() > 0) {
4453 oop obj = _evac_failure_scan_stack->pop();
4454 _evac_failure_closure->set_region(heap_region_containing(obj));
4455 obj->oop_iterate_backwards(_evac_failure_closure);
4456 }
4457 }
4458
4459 oop
4460 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4461 oop old) {
4462 assert(obj_in_cs(old),
4463 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4464 (HeapWord*) old));
4465 markOop m = old->mark();
4466 oop forward_ptr = old->forward_to_atomic(old);
4467 if (forward_ptr == NULL) {
4468 // Forward-to-self succeeded.
4469 assert(_par_scan_state != NULL, "par scan state");
4470 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4471 uint queue_num = _par_scan_state->queue_num();
4472
4473 _evacuation_failed = true;
4474 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4475 if (_evac_failure_closure != cl) {
4476 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4477 assert(!_drain_in_progress,
4478 "Should only be true while someone holds the lock.");
4479 // Set the global evac-failure closure to the current thread's.
4480 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4481 set_evac_failure_closure(cl);
4482 // Now do the common part.
4483 handle_evacuation_failure_common(old, m);
4484 // Reset to NULL.
4485 set_evac_failure_closure(NULL);
4486 } else {
4487 // The lock is already held, and this is recursive.
4488 assert(_drain_in_progress, "This should only be the recursive case.");
4489 handle_evacuation_failure_common(old, m);
4490 }
4491 return old;
4492 } else {
4493 // Forward-to-self failed. Either someone else managed to allocate
4494 // space for this object (old != forward_ptr) or they beat us in
4495 // self-forwarding it (old == forward_ptr).
4496 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4497 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4498 "should not be in the CSet",
4499 (HeapWord*) old, (HeapWord*) forward_ptr));
4500 return forward_ptr;
4501 }
4502 }
4503
4504 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4505 preserve_mark_if_necessary(old, m);
4506
4507 HeapRegion* r = heap_region_containing(old);
4508 if (!r->evacuation_failed()) {
4509 r->set_evacuation_failed(true);
4510 _hr_printer.evac_failure(r);
4511 }
4512
4513 push_on_evac_failure_scan_stack(old);
4514
4515 if (!_drain_in_progress) {
4516 // prevent recursion in copy_to_survivor_space()
4517 _drain_in_progress = true;
4518 drain_evac_failure_scan_stack();
4519 _drain_in_progress = false;
4520 }
4521 }
4522
4523 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4524 assert(evacuation_failed(), "Oversaving!");
4525 // We want to call the "for_promotion_failure" version only in the
4526 // case of a promotion failure.
4527 if (m->must_be_preserved_for_promotion_failure(obj)) {
4528 _objs_with_preserved_marks.push(obj);
4529 _preserved_marks_of_objs.push(m);
4530 }
4531 }
4532
4533 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4534 size_t word_size) {
4535 if (purpose == GCAllocForSurvived) {
4536 HeapWord* result = survivor_attempt_allocation(word_size);
4537 if (result != NULL) {
4538 return result;
4539 } else {
4540 // Let's try to allocate in the old gen in case we can fit the
4541 // object there.
4542 return old_attempt_allocation(word_size);
4543 }
4544 } else {
4545 assert(purpose == GCAllocForTenured, "sanity");
4546 HeapWord* result = old_attempt_allocation(word_size);
4547 if (result != NULL) {
4548 return result;
4549 } else {
4550 // Let's try to allocate in the survivors in case we can fit the
4551 // object there.
4552 return survivor_attempt_allocation(word_size);
4553 }
4554 }
4555
4556 ShouldNotReachHere();
4557 // Trying to keep some compilers happy.
4558 return NULL;
4559 }
4560
4561 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4562 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4563
4564 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4565 : _g1h(g1h),
4566 _refs(g1h->task_queue(queue_num)),
4567 _dcq(&g1h->dirty_card_queue_set()),
4568 _ct_bs(g1h->g1_barrier_set()),
4569 _g1_rem(g1h->g1_rem_set()),
4570 _hash_seed(17), _queue_num(queue_num),
4571 _term_attempts(0),
4572 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4573 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4574 _age_table(false),
4575 _strong_roots_time(0), _term_time(0),
4576 _alloc_buffer_waste(0), _undo_waste(0) {
4577 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4578 // we "sacrifice" entry 0 to keep track of surviving bytes for
4579 // non-young regions (where the age is -1)
4580 // We also add a few elements at the beginning and at the end in
4581 // an attempt to eliminate cache contention
4582 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4583 uint array_length = PADDING_ELEM_NUM +
4584 real_length +
4585 PADDING_ELEM_NUM;
4586 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4587 if (_surviving_young_words_base == NULL)
4588 vm_exit_out_of_memory(array_length * sizeof(size_t),
4589 "Not enough space for young surv histo.");
4590 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4591 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4592
4593 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4594 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4595
4596 _start = os::elapsedTime();
4597 }
4598
4599 void
4600 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4601 {
4602 st->print_raw_cr("GC Termination Stats");
4603 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4604 " ------waste (KiB)------");
4605 st->print_raw_cr("thr ms ms % ms % attempts"
4606 " total alloc undo");
4607 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4608 " ------- ------- -------");
4609 }
4610
4611 void
4612 G1ParScanThreadState::print_termination_stats(int i,
4613 outputStream* const st) const
4614 {
4615 const double elapsed_ms = elapsed_time() * 1000.0;
4616 const double s_roots_ms = strong_roots_time() * 1000.0;
4617 const double term_ms = term_time() * 1000.0;
4618 st->print_cr("%3d %9.2f %9.2f %6.2f "
4619 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4620 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4621 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4622 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4623 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4624 alloc_buffer_waste() * HeapWordSize / K,
4625 undo_waste() * HeapWordSize / K);
4626 }
4627
4628 #ifdef ASSERT
4629 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4630 assert(ref != NULL, "invariant");
4631 assert(UseCompressedOops, "sanity");
4632 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4633 oop p = oopDesc::load_decode_heap_oop(ref);
4634 assert(_g1h->is_in_g1_reserved(p),
4635 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4636 return true;
4637 }
4638
4639 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4640 assert(ref != NULL, "invariant");
4641 if (has_partial_array_mask(ref)) {
4642 // Must be in the collection set--it's already been copied.
4643 oop p = clear_partial_array_mask(ref);
4644 assert(_g1h->obj_in_cs(p),
4645 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4646 } else {
4647 oop p = oopDesc::load_decode_heap_oop(ref);
4648 assert(_g1h->is_in_g1_reserved(p),
4649 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4650 }
4651 return true;
4652 }
4653
4654 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4655 if (ref.is_narrow()) {
4656 return verify_ref((narrowOop*) ref);
4657 } else {
4658 return verify_ref((oop*) ref);
4659 }
4660 }
4661 #endif // ASSERT
4662
4663 void G1ParScanThreadState::trim_queue() {
4664 assert(_evac_cl != NULL, "not set");
4665 assert(_evac_failure_cl != NULL, "not set");
4666 assert(_partial_scan_cl != NULL, "not set");
4667
4668 StarTask ref;
4669 do {
4670 // Drain the overflow stack first, so other threads can steal.
4671 while (refs()->pop_overflow(ref)) {
4672 deal_with_reference(ref);
4673 }
4674
4675 while (refs()->pop_local(ref)) {
4676 deal_with_reference(ref);
4677 }
4678 } while (!refs()->is_empty());
4679 }
4680
4681 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4682 G1ParScanThreadState* par_scan_state) :
4683 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4684 _par_scan_state(par_scan_state),
4685 _worker_id(par_scan_state->queue_num()),
4686 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4687 _mark_in_progress(_g1->mark_in_progress()) { }
4688
4689 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4690 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4691 #ifdef ASSERT
4692 HeapRegion* hr = _g1->heap_region_containing(obj);
4693 assert(hr != NULL, "sanity");
4694 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4695 #endif // ASSERT
4696
4697 // We know that the object is not moving so it's safe to read its size.
4698 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4699 }
4700
4701 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4702 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4703 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4704 #ifdef ASSERT
4705 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4706 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4707 assert(from_obj != to_obj, "should not be self-forwarded");
4708
4709 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4710 assert(from_hr != NULL, "sanity");
4711 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4712
4713 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4714 assert(to_hr != NULL, "sanity");
4715 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4716 #endif // ASSERT
4717
4718 // The object might be in the process of being copied by another
4719 // worker so we cannot trust that its to-space image is
4720 // well-formed. So we have to read its size from its from-space
4721 // image which we know should not be changing.
4722 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4723 }
4724
4725 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4726 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4727 ::copy_to_survivor_space(oop old) {
4728 size_t word_sz = old->size();
4729 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4730 // +1 to make the -1 indexes valid...
4731 int young_index = from_region->young_index_in_cset()+1;
4732 assert( (from_region->is_young() && young_index > 0) ||
4733 (!from_region->is_young() && young_index == 0), "invariant" );
4734 G1CollectorPolicy* g1p = _g1->g1_policy();
4735 markOop m = old->mark();
4736 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4737 : m->age();
4738 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4739 word_sz);
4740 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4741 #ifndef PRODUCT
4742 // Should this evacuation fail?
4743 if (_g1->evacuation_should_fail()) {
4744 if (obj_ptr != NULL) {
4745 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4746 obj_ptr = NULL;
4747 }
4748 }
4749 #endif // !PRODUCT
4750
4751 if (obj_ptr == NULL) {
4752 // This will either forward-to-self, or detect that someone else has
4753 // installed a forwarding pointer.
4754 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4755 }
4756
4757 oop obj = oop(obj_ptr);
4758
4759 // We're going to allocate linearly, so might as well prefetch ahead.
4760 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4761
4762 oop forward_ptr = old->forward_to_atomic(obj);
4763 if (forward_ptr == NULL) {
4764 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4765 if (g1p->track_object_age(alloc_purpose)) {
4766 // We could simply do obj->incr_age(). However, this causes a
4767 // performance issue. obj->incr_age() will first check whether
4768 // the object has a displaced mark by checking its mark word;
4769 // getting the mark word from the new location of the object
4770 // stalls. So, given that we already have the mark word and we
4771 // are about to install it anyway, it's better to increase the
4772 // age on the mark word, when the object does not have a
4773 // displaced mark word. We're not expecting many objects to have
4774 // a displaced marked word, so that case is not optimized
4775 // further (it could be...) and we simply call obj->incr_age().
4776
4777 if (m->has_displaced_mark_helper()) {
4778 // in this case, we have to install the mark word first,
4779 // otherwise obj looks to be forwarded (the old mark word,
4780 // which contains the forward pointer, was copied)
4781 obj->set_mark(m);
4782 obj->incr_age();
4783 } else {
4784 m = m->incr_age();
4785 obj->set_mark(m);
4786 }
4787 _par_scan_state->age_table()->add(obj, word_sz);
4788 } else {
4789 obj->set_mark(m);
4790 }
4791
4792 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4793 surv_young_words[young_index] += word_sz;
4794
4795 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4796 // We keep track of the next start index in the length field of
4797 // the to-space object. The actual length can be found in the
4798 // length field of the from-space object.
4799 arrayOop(obj)->set_length(0);
4800 oop* old_p = set_partial_array_mask(old);
4801 _par_scan_state->push_on_queue(old_p);
4802 } else {
4803 // No point in using the slower heap_region_containing() method,
4804 // given that we know obj is in the heap.
4805 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4806 obj->oop_iterate_backwards(&_scanner);
4807 }
4808 } else {
4809 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4810 obj = forward_ptr;
4811 }
4812 return obj;
4813 }
4814
4815 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4816 template <class T>
4817 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4818 ::do_oop_work(T* p) {
4819 oop obj = oopDesc::load_decode_heap_oop(p);
4820 assert(barrier != G1BarrierRS || obj != NULL,
4821 "Precondition: G1BarrierRS implies obj is non-NULL");
4822
4823 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4824
4825 // here the null check is implicit in the cset_fast_test() test
4826 if (_g1->in_cset_fast_test(obj)) {
4827 oop forwardee;
4828 if (obj->is_forwarded()) {
4829 forwardee = obj->forwardee();
4830 } else {
4831 forwardee = copy_to_survivor_space(obj);
4832 }
4833 assert(forwardee != NULL, "forwardee should not be NULL");
4834 oopDesc::encode_store_heap_oop(p, forwardee);
4835 if (do_mark_object && forwardee != obj) {
4836 // If the object is self-forwarded we don't need to explicitly
4837 // mark it, the evacuation failure protocol will do so.
4838 mark_forwarded_object(obj, forwardee);
4839 }
4840
4841 // When scanning the RS, we only care about objs in CS.
4842 if (barrier == G1BarrierRS) {
4843 _par_scan_state->update_rs(_from, p, _worker_id);
4844 }
4845 } else {
4846 // The object is not in collection set. If we're a root scanning
4847 // closure during an initial mark pause (i.e. do_mark_object will
4848 // be true) then attempt to mark the object.
4849 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4850 mark_object(obj);
4851 }
4852 }
4853
4854 if (barrier == G1BarrierEvac && obj != NULL) {
4855 _par_scan_state->update_rs(_from, p, _worker_id);
4856 }
4857
4858 if (do_gen_barrier && obj != NULL) {
4859 par_do_barrier(p);
4860 }
4861 }
4862
4863 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4864 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4865
4866 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4867 assert(has_partial_array_mask(p), "invariant");
4868 oop from_obj = clear_partial_array_mask(p);
4869
4870 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4871 assert(from_obj->is_objArray(), "must be obj array");
4872 objArrayOop from_obj_array = objArrayOop(from_obj);
4873 // The from-space object contains the real length.
4874 int length = from_obj_array->length();
4875
4876 assert(from_obj->is_forwarded(), "must be forwarded");
4877 oop to_obj = from_obj->forwardee();
4878 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4879 objArrayOop to_obj_array = objArrayOop(to_obj);
4880 // We keep track of the next start index in the length field of the
4881 // to-space object.
4882 int next_index = to_obj_array->length();
4883 assert(0 <= next_index && next_index < length,
4884 err_msg("invariant, next index: %d, length: %d", next_index, length));
4885
4886 int start = next_index;
4887 int end = length;
4888 int remainder = end - start;
4889 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4890 if (remainder > 2 * ParGCArrayScanChunk) {
4891 end = start + ParGCArrayScanChunk;
4892 to_obj_array->set_length(end);
4893 // Push the remainder before we process the range in case another
4894 // worker has run out of things to do and can steal it.
4895 oop* from_obj_p = set_partial_array_mask(from_obj);
4896 _par_scan_state->push_on_queue(from_obj_p);
4897 } else {
4898 assert(length == end, "sanity");
4899 // We'll process the final range for this object. Restore the length
4900 // so that the heap remains parsable in case of evacuation failure.
4901 to_obj_array->set_length(end);
4902 }
4903 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4904 // Process indexes [start,end). It will also process the header
4905 // along with the first chunk (i.e., the chunk with start == 0).
4906 // Note that at this point the length field of to_obj_array is not
4907 // correct given that we are using it to keep track of the next
4908 // start index. oop_iterate_range() (thankfully!) ignores the length
4909 // field and only relies on the start / end parameters. It does
4910 // however return the size of the object which will be incorrect. So
4911 // we have to ignore it even if we wanted to use it.
4912 to_obj_array->oop_iterate_range(&_scanner, start, end);
4913 }
4914
4915 class G1ParEvacuateFollowersClosure : public VoidClosure {
4916 protected:
4917 G1CollectedHeap* _g1h;
4918 G1ParScanThreadState* _par_scan_state;
4919 RefToScanQueueSet* _queues;
4920 ParallelTaskTerminator* _terminator;
4921
4922 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4923 RefToScanQueueSet* queues() { return _queues; }
4924 ParallelTaskTerminator* terminator() { return _terminator; }
4925
4926 public:
4927 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4928 G1ParScanThreadState* par_scan_state,
4929 RefToScanQueueSet* queues,
4930 ParallelTaskTerminator* terminator)
4931 : _g1h(g1h), _par_scan_state(par_scan_state),
4932 _queues(queues), _terminator(terminator) {}
4933
4934 void do_void();
4935
4936 private:
4937 inline bool offer_termination();
4938 };
4939
4940 bool G1ParEvacuateFollowersClosure::offer_termination() {
4941 G1ParScanThreadState* const pss = par_scan_state();
4942 pss->start_term_time();
4943 const bool res = terminator()->offer_termination();
4944 pss->end_term_time();
4945 return res;
4946 }
4947
4948 void G1ParEvacuateFollowersClosure::do_void() {
4949 StarTask stolen_task;
4950 G1ParScanThreadState* const pss = par_scan_state();
4951 pss->trim_queue();
4952
4953 do {
4954 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4955 assert(pss->verify_task(stolen_task), "sanity");
4956 if (stolen_task.is_narrow()) {
4957 pss->deal_with_reference((narrowOop*) stolen_task);
4958 } else {
4959 pss->deal_with_reference((oop*) stolen_task);
4960 }
4961
4962 // We've just processed a reference and we might have made
4963 // available new entries on the queues. So we have to make sure
4964 // we drain the queues as necessary.
4965 pss->trim_queue();
4966 }
4967 } while (!offer_termination());
4968
4969 pss->retire_alloc_buffers();
4970 }
4971
4972 class G1ParTask : public AbstractGangTask {
4973 protected:
4974 G1CollectedHeap* _g1h;
4975 RefToScanQueueSet *_queues;
4976 ParallelTaskTerminator _terminator;
4977 uint _n_workers;
4978
4979 Mutex _stats_lock;
4980 Mutex* stats_lock() { return &_stats_lock; }
4981
4982 size_t getNCards() {
4983 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4984 / G1BlockOffsetSharedArray::N_bytes;
4985 }
4986
4987 public:
4988 G1ParTask(G1CollectedHeap* g1h,
4989 RefToScanQueueSet *task_queues)
4990 : AbstractGangTask("G1 collection"),
4991 _g1h(g1h),
4992 _queues(task_queues),
4993 _terminator(0, _queues),
4994 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4995 {}
4996
4997 RefToScanQueueSet* queues() { return _queues; }
4998
4999 RefToScanQueue *work_queue(int i) {
5000 return queues()->queue(i);
5001 }
5002
5003 ParallelTaskTerminator* terminator() { return &_terminator; }
5004
5005 virtual void set_for_termination(int active_workers) {
5006 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5007 // in the young space (_par_seq_tasks) in the G1 heap
5008 // for SequentialSubTasksDone.
5009 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5010 // both of which need setting by set_n_termination().
5011 _g1h->SharedHeap::set_n_termination(active_workers);
5012 _g1h->set_n_termination(active_workers);
5013 terminator()->reset_for_reuse(active_workers);
5014 _n_workers = active_workers;
5015 }
5016
5017 void work(uint worker_id) {
5018 if (worker_id >= _n_workers) return; // no work needed this round
5019
5020 double start_time_ms = os::elapsedTime() * 1000.0;
5021 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5022
5023 {
5024 ResourceMark rm;
5025 HandleMark hm;
5026
5027 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5028
5029 G1ParScanThreadState pss(_g1h, worker_id);
5030 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5031 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5032 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5033
5034 pss.set_evac_closure(&scan_evac_cl);
5035 pss.set_evac_failure_closure(&evac_failure_cl);
5036 pss.set_partial_scan_closure(&partial_scan_cl);
5037
5038 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5039 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp);
5040
5041 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5042 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp);
5043
5044 OopClosure* scan_root_cl = &only_scan_root_cl;
5045 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl;
5046
5047 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5048 // We also need to mark copied objects.
5049 scan_root_cl = &scan_mark_root_cl;
5050 scan_perm_cl = &scan_mark_perm_cl;
5051 }
5052
5053 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5054
5055 pss.start_strong_roots();
5056 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
5057 SharedHeap::SO_AllClasses,
5058 scan_root_cl,
5059 &push_heap_rs_cl,
5060 scan_perm_cl,
5061 worker_id,
5062 /* manages_code_roots */ true);
5063 pss.end_strong_roots();
5064
5065 {
5066 double start = os::elapsedTime();
5067 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5068 evac.do_void();
5069 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5070 double term_ms = pss.term_time()*1000.0;
5071 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5072 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5073 }
5074 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5075 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5076
5077 if (ParallelGCVerbose) {
5078 MutexLocker x(stats_lock());
5079 pss.print_termination_stats(worker_id);
5080 }
5081
5082 assert(pss.refs()->is_empty(), "should be empty");
5083
5084 // Close the inner scope so that the ResourceMark and HandleMark
5085 // destructors are executed here and are included as part of the
5086 // "GC Worker Time".
5087 }
5088
5089 double end_time_ms = os::elapsedTime() * 1000.0;
5090 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5091 }
5092 };
5093
5094 // *** Common G1 Evacuation Stuff
5095
5096 // This method is run in a GC worker.
5097
5098 void
5099 G1CollectedHeap::
5100 g1_process_strong_roots(bool collecting_perm_gen,
5101 ScanningOption so,
5102 OopClosure* scan_non_heap_roots,
5103 OopsInHeapRegionClosure* scan_rs,
5104 OopsInGenClosure* scan_perm,
5105 int worker_i,
5106 bool manages_code_roots) {
5107
5108 // First scan the strong roots, including the perm gen.
5109 double ext_roots_start = os::elapsedTime();
5110 double closure_app_time_sec = 0.0;
5111
5112 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5113 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
5114 buf_scan_perm.set_generation(perm_gen());
5115
5116 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5117 // Walk the code cache/strong code roots w/o buffering, because StarTask
5118 // cannot handle unaligned oop locations.
5119 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5120
5121 process_strong_roots(false, // no scoping; this is parallel code
5122 collecting_perm_gen, so,
5123 &buf_scan_non_heap_roots,
5124 &eager_scan_code_roots,
5125 &buf_scan_perm,
5126 manages_code_roots);
5127
5128 // Now the CM ref_processor roots.
5129 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5130 // We need to treat the discovered reference lists of the
5131 // concurrent mark ref processor as roots and keep entries
5132 // (which are added by the marking threads) on them live
5133 // until they can be processed at the end of marking.
5134 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5135 }
5136
5137 // Finish up any enqueued closure apps (attributed as object copy time).
5138 buf_scan_non_heap_roots.done();
5139 buf_scan_perm.done();
5140
5141 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
5142 buf_scan_non_heap_roots.closure_app_seconds();
5143 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5144
5145 double ext_root_time_ms =
5146 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5147
5148 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5149
5150 // During conc marking we have to filter the per-thread SATB buffers
5151 // to make sure we remove any oops into the CSet (which will show up
5152 // as implicitly live).
5153 double satb_filtering_ms = 0.0;
5154 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5155 if (mark_in_progress()) {
5156 double satb_filter_start = os::elapsedTime();
5157
5158 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5159
5160 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5161 }
5162 }
5163 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5164
5165 // If this is an initial mark pause, and we're not scanning
5166 // the entire code cache, we need to mark the oops in the
5167 // strong code root lists for the regions that are not in
5168 // the collection set.
5169 // Note all threads participate in this set of root tasks.
5170 double mark_strong_code_roots_ms = 0.0;
5171 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5172 double mark_strong_roots_start = os::elapsedTime();
5173 mark_strong_code_roots(worker_i);
5174 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5175 }
5176 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5177
5178 // Now scan the complement of the collection set.
5179 if (scan_rs != NULL) {
5180 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5181 }
5182
5183 _process_strong_tasks->all_tasks_completed();
5184 }
5185
5186 void
5187 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
5188 OopClosure* non_root_closure) {
5189 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5190 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
5191 }
5192
5193 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5194 private:
5195 BoolObjectClosure* _is_alive;
5196 int _initial_string_table_size;
5197 int _initial_symbol_table_size;
5198
5199 bool _process_strings;
5200 int _strings_processed;
5201 int _strings_removed;
5202
5203 bool _process_symbols;
5204 int _symbols_processed;
5205 int _symbols_removed;
5206
5207 bool _do_in_parallel;
5208 public:
5209 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5210 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5211 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5212 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5213 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5214
5215 _initial_string_table_size = StringTable::the_table()->table_size();
5216 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5217 if (process_strings) {
5218 StringTable::clear_parallel_claimed_index();
5219 }
5220 if (process_symbols) {
5221 SymbolTable::clear_parallel_claimed_index();
5222 }
5223 }
5224
5225 ~G1StringSymbolTableUnlinkTask() {
5226 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5227 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5228 StringTable::parallel_claimed_index(), _initial_string_table_size));
5229 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5230 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5231 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5232 }
5233
5234 void work(uint worker_id) {
5235 if (_do_in_parallel) {
5236 int strings_processed = 0;
5237 int strings_removed = 0;
5238 int symbols_processed = 0;
5239 int symbols_removed = 0;
5240 if (_process_strings) {
5241 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5242 Atomic::add(strings_processed, &_strings_processed);
5243 Atomic::add(strings_removed, &_strings_removed);
5244 }
5245 if (_process_symbols) {
5246 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5247 Atomic::add(symbols_processed, &_symbols_processed);
5248 Atomic::add(symbols_removed, &_symbols_removed);
5249 }
5250 } else {
5251 if (_process_strings) {
5252 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5253 }
5254 if (_process_symbols) {
5255 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5256 }
5257 }
5258 }
5259
5260 size_t strings_processed() const { return (size_t)_strings_processed; }
5261 size_t strings_removed() const { return (size_t)_strings_removed; }
5262
5263 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5264 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5265 };
5266
5267 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5268 bool process_strings, bool process_symbols) {
5269 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5270 _g1h->workers()->active_workers() : 1);
5271
5272 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5273 if (G1CollectedHeap::use_parallel_gc_threads()) {
5274 set_par_threads(n_workers);
5275 workers()->run_task(&g1_unlink_task);
5276 set_par_threads(0);
5277 } else {
5278 g1_unlink_task.work(0);
5279 }
5280 if (G1TraceStringSymbolTableScrubbing) {
5281 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5282 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5283 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5284 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5285 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5286 }
5287 }
5288
5289 // Weak Reference Processing support
5290
5291 // An always "is_alive" closure that is used to preserve referents.
5292 // If the object is non-null then it's alive. Used in the preservation
5293 // of referent objects that are pointed to by reference objects
5294 // discovered by the CM ref processor.
5295 class G1AlwaysAliveClosure: public BoolObjectClosure {
5296 G1CollectedHeap* _g1;
5297 public:
5298 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5299 void do_object(oop p) { assert(false, "Do not call."); }
5300 bool do_object_b(oop p) {
5301 if (p != NULL) {
5302 return true;
5303 }
5304 return false;
5305 }
5306 };
5307
5308 bool G1STWIsAliveClosure::do_object_b(oop p) {
5309 // An object is reachable if it is outside the collection set,
5310 // or is inside and copied.
5311 return !_g1->obj_in_cs(p) || p->is_forwarded();
5312 }
5313
5314 // Non Copying Keep Alive closure
5315 class G1KeepAliveClosure: public OopClosure {
5316 G1CollectedHeap* _g1;
5317 public:
5318 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5319 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5320 void do_oop( oop* p) {
5321 oop obj = *p;
5322
5323 if (_g1->obj_in_cs(obj)) {
5324 assert( obj->is_forwarded(), "invariant" );
5325 *p = obj->forwardee();
5326 }
5327 }
5328 };
5329
5330 // Copying Keep Alive closure - can be called from both
5331 // serial and parallel code as long as different worker
5332 // threads utilize different G1ParScanThreadState instances
5333 // and different queues.
5334
5335 class G1CopyingKeepAliveClosure: public OopClosure {
5336 G1CollectedHeap* _g1h;
5337 OopClosure* _copy_non_heap_obj_cl;
5338 OopsInHeapRegionClosure* _copy_perm_obj_cl;
5339 G1ParScanThreadState* _par_scan_state;
5340
5341 public:
5342 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5343 OopClosure* non_heap_obj_cl,
5344 OopsInHeapRegionClosure* perm_obj_cl,
5345 G1ParScanThreadState* pss):
5346 _g1h(g1h),
5347 _copy_non_heap_obj_cl(non_heap_obj_cl),
5348 _copy_perm_obj_cl(perm_obj_cl),
5349 _par_scan_state(pss)
5350 {}
5351
5352 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5353 virtual void do_oop( oop* p) { do_oop_work(p); }
5354
5355 template <class T> void do_oop_work(T* p) {
5356 oop obj = oopDesc::load_decode_heap_oop(p);
5357
5358 if (_g1h->obj_in_cs(obj)) {
5359 // If the referent object has been forwarded (either copied
5360 // to a new location or to itself in the event of an
5361 // evacuation failure) then we need to update the reference
5362 // field and, if both reference and referent are in the G1
5363 // heap, update the RSet for the referent.
5364 //
5365 // If the referent has not been forwarded then we have to keep
5366 // it alive by policy. Therefore we have copy the referent.
5367 //
5368 // If the reference field is in the G1 heap then we can push
5369 // on the PSS queue. When the queue is drained (after each
5370 // phase of reference processing) the object and it's followers
5371 // will be copied, the reference field set to point to the
5372 // new location, and the RSet updated. Otherwise we need to
5373 // use the the non-heap or perm closures directly to copy
5374 // the referent object and update the pointer, while avoiding
5375 // updating the RSet.
5376
5377 if (_g1h->is_in_g1_reserved(p)) {
5378 _par_scan_state->push_on_queue(p);
5379 } else {
5380 // The reference field is not in the G1 heap.
5381 if (_g1h->perm_gen()->is_in(p)) {
5382 _copy_perm_obj_cl->do_oop(p);
5383 } else {
5384 _copy_non_heap_obj_cl->do_oop(p);
5385 }
5386 }
5387 }
5388 }
5389 };
5390
5391 // Serial drain queue closure. Called as the 'complete_gc'
5392 // closure for each discovered list in some of the
5393 // reference processing phases.
5394
5395 class G1STWDrainQueueClosure: public VoidClosure {
5396 protected:
5397 G1CollectedHeap* _g1h;
5398 G1ParScanThreadState* _par_scan_state;
5399
5400 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5401
5402 public:
5403 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5404 _g1h(g1h),
5405 _par_scan_state(pss)
5406 { }
5407
5408 void do_void() {
5409 G1ParScanThreadState* const pss = par_scan_state();
5410 pss->trim_queue();
5411 }
5412 };
5413
5414 // Parallel Reference Processing closures
5415
5416 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5417 // processing during G1 evacuation pauses.
5418
5419 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5420 private:
5421 G1CollectedHeap* _g1h;
5422 RefToScanQueueSet* _queues;
5423 FlexibleWorkGang* _workers;
5424 int _active_workers;
5425
5426 public:
5427 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5428 FlexibleWorkGang* workers,
5429 RefToScanQueueSet *task_queues,
5430 int n_workers) :
5431 _g1h(g1h),
5432 _queues(task_queues),
5433 _workers(workers),
5434 _active_workers(n_workers)
5435 {
5436 assert(n_workers > 0, "shouldn't call this otherwise");
5437 }
5438
5439 // Executes the given task using concurrent marking worker threads.
5440 virtual void execute(ProcessTask& task);
5441 virtual void execute(EnqueueTask& task);
5442 };
5443
5444 // Gang task for possibly parallel reference processing
5445
5446 class G1STWRefProcTaskProxy: public AbstractGangTask {
5447 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5448 ProcessTask& _proc_task;
5449 G1CollectedHeap* _g1h;
5450 RefToScanQueueSet *_task_queues;
5451 ParallelTaskTerminator* _terminator;
5452
5453 public:
5454 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5455 G1CollectedHeap* g1h,
5456 RefToScanQueueSet *task_queues,
5457 ParallelTaskTerminator* terminator) :
5458 AbstractGangTask("Process reference objects in parallel"),
5459 _proc_task(proc_task),
5460 _g1h(g1h),
5461 _task_queues(task_queues),
5462 _terminator(terminator)
5463 {}
5464
5465 virtual void work(uint worker_id) {
5466 // The reference processing task executed by a single worker.
5467 ResourceMark rm;
5468 HandleMark hm;
5469
5470 G1STWIsAliveClosure is_alive(_g1h);
5471
5472 G1ParScanThreadState pss(_g1h, worker_id);
5473
5474 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5475 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5476 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5477
5478 pss.set_evac_closure(&scan_evac_cl);
5479 pss.set_evac_failure_closure(&evac_failure_cl);
5480 pss.set_partial_scan_closure(&partial_scan_cl);
5481
5482 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5483 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5484
5485 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5486 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5487
5488 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5489 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5490
5491 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5492 // We also need to mark copied objects.
5493 copy_non_heap_cl = ©_mark_non_heap_cl;
5494 copy_perm_cl = ©_mark_perm_cl;
5495 }
5496
5497 // Keep alive closure.
5498 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5499
5500 // Complete GC closure
5501 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5502
5503 // Call the reference processing task's work routine.
5504 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5505
5506 // Note we cannot assert that the refs array is empty here as not all
5507 // of the processing tasks (specifically phase2 - pp2_work) execute
5508 // the complete_gc closure (which ordinarily would drain the queue) so
5509 // the queue may not be empty.
5510 }
5511 };
5512
5513 // Driver routine for parallel reference processing.
5514 // Creates an instance of the ref processing gang
5515 // task and has the worker threads execute it.
5516 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5517 assert(_workers != NULL, "Need parallel worker threads.");
5518
5519 ParallelTaskTerminator terminator(_active_workers, _queues);
5520 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5521
5522 _g1h->set_par_threads(_active_workers);
5523 _workers->run_task(&proc_task_proxy);
5524 _g1h->set_par_threads(0);
5525 }
5526
5527 // Gang task for parallel reference enqueueing.
5528
5529 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5530 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5531 EnqueueTask& _enq_task;
5532
5533 public:
5534 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5535 AbstractGangTask("Enqueue reference objects in parallel"),
5536 _enq_task(enq_task)
5537 { }
5538
5539 virtual void work(uint worker_id) {
5540 _enq_task.work(worker_id);
5541 }
5542 };
5543
5544 // Driver routine for parallel reference enqueueing.
5545 // Creates an instance of the ref enqueueing gang
5546 // task and has the worker threads execute it.
5547
5548 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5549 assert(_workers != NULL, "Need parallel worker threads.");
5550
5551 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5552
5553 _g1h->set_par_threads(_active_workers);
5554 _workers->run_task(&enq_task_proxy);
5555 _g1h->set_par_threads(0);
5556 }
5557
5558 // End of weak reference support closures
5559
5560 // Abstract task used to preserve (i.e. copy) any referent objects
5561 // that are in the collection set and are pointed to by reference
5562 // objects discovered by the CM ref processor.
5563
5564 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5565 protected:
5566 G1CollectedHeap* _g1h;
5567 RefToScanQueueSet *_queues;
5568 ParallelTaskTerminator _terminator;
5569 uint _n_workers;
5570
5571 public:
5572 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5573 AbstractGangTask("ParPreserveCMReferents"),
5574 _g1h(g1h),
5575 _queues(task_queues),
5576 _terminator(workers, _queues),
5577 _n_workers(workers)
5578 { }
5579
5580 void work(uint worker_id) {
5581 ResourceMark rm;
5582 HandleMark hm;
5583
5584 G1ParScanThreadState pss(_g1h, worker_id);
5585 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5586 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5587 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5588
5589 pss.set_evac_closure(&scan_evac_cl);
5590 pss.set_evac_failure_closure(&evac_failure_cl);
5591 pss.set_partial_scan_closure(&partial_scan_cl);
5592
5593 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5594
5595
5596 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5597 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5598
5599 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5600 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5601
5602 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5603 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5604
5605 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5606 // We also need to mark copied objects.
5607 copy_non_heap_cl = ©_mark_non_heap_cl;
5608 copy_perm_cl = ©_mark_perm_cl;
5609 }
5610
5611 // Is alive closure
5612 G1AlwaysAliveClosure always_alive(_g1h);
5613
5614 // Copying keep alive closure. Applied to referent objects that need
5615 // to be copied.
5616 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5617
5618 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5619
5620 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5621 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5622
5623 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5624 // So this must be true - but assert just in case someone decides to
5625 // change the worker ids.
5626 assert(0 <= worker_id && worker_id < limit, "sanity");
5627 assert(!rp->discovery_is_atomic(), "check this code");
5628
5629 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5630 for (uint idx = worker_id; idx < limit; idx += stride) {
5631 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5632
5633 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5634 while (iter.has_next()) {
5635 // Since discovery is not atomic for the CM ref processor, we
5636 // can see some null referent objects.
5637 iter.load_ptrs(DEBUG_ONLY(true));
5638 oop ref = iter.obj();
5639
5640 // This will filter nulls.
5641 if (iter.is_referent_alive()) {
5642 iter.make_referent_alive();
5643 }
5644 iter.move_to_next();
5645 }
5646 }
5647
5648 // Drain the queue - which may cause stealing
5649 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5650 drain_queue.do_void();
5651 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5652 assert(pss.refs()->is_empty(), "should be");
5653 }
5654 };
5655
5656 // Weak Reference processing during an evacuation pause (part 1).
5657 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5658 double ref_proc_start = os::elapsedTime();
5659
5660 ReferenceProcessor* rp = _ref_processor_stw;
5661 assert(rp->discovery_enabled(), "should have been enabled");
5662
5663 // Any reference objects, in the collection set, that were 'discovered'
5664 // by the CM ref processor should have already been copied (either by
5665 // applying the external root copy closure to the discovered lists, or
5666 // by following an RSet entry).
5667 //
5668 // But some of the referents, that are in the collection set, that these
5669 // reference objects point to may not have been copied: the STW ref
5670 // processor would have seen that the reference object had already
5671 // been 'discovered' and would have skipped discovering the reference,
5672 // but would not have treated the reference object as a regular oop.
5673 // As a result the copy closure would not have been applied to the
5674 // referent object.
5675 //
5676 // We need to explicitly copy these referent objects - the references
5677 // will be processed at the end of remarking.
5678 //
5679 // We also need to do this copying before we process the reference
5680 // objects discovered by the STW ref processor in case one of these
5681 // referents points to another object which is also referenced by an
5682 // object discovered by the STW ref processor.
5683
5684 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5685 no_of_gc_workers == workers()->active_workers(),
5686 "Need to reset active GC workers");
5687
5688 set_par_threads(no_of_gc_workers);
5689 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5690 no_of_gc_workers,
5691 _task_queues);
5692
5693 if (G1CollectedHeap::use_parallel_gc_threads()) {
5694 workers()->run_task(&keep_cm_referents);
5695 } else {
5696 keep_cm_referents.work(0);
5697 }
5698
5699 set_par_threads(0);
5700
5701 // Closure to test whether a referent is alive.
5702 G1STWIsAliveClosure is_alive(this);
5703
5704 // Even when parallel reference processing is enabled, the processing
5705 // of JNI refs is serial and performed serially by the current thread
5706 // rather than by a worker. The following PSS will be used for processing
5707 // JNI refs.
5708
5709 // Use only a single queue for this PSS.
5710 G1ParScanThreadState pss(this, 0);
5711
5712 // We do not embed a reference processor in the copying/scanning
5713 // closures while we're actually processing the discovered
5714 // reference objects.
5715 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5716 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5717 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5718
5719 pss.set_evac_closure(&scan_evac_cl);
5720 pss.set_evac_failure_closure(&evac_failure_cl);
5721 pss.set_partial_scan_closure(&partial_scan_cl);
5722
5723 assert(pss.refs()->is_empty(), "pre-condition");
5724
5725 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5726 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL);
5727
5728 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5729 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL);
5730
5731 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5732 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5733
5734 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5735 // We also need to mark copied objects.
5736 copy_non_heap_cl = ©_mark_non_heap_cl;
5737 copy_perm_cl = ©_mark_perm_cl;
5738 }
5739
5740 // Keep alive closure.
5741 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5742
5743 // Serial Complete GC closure
5744 G1STWDrainQueueClosure drain_queue(this, &pss);
5745
5746 // Setup the soft refs policy...
5747 rp->setup_policy(false);
5748
5749 ReferenceProcessorStats stats;
5750 if (!rp->processing_is_mt()) {
5751 // Serial reference processing...
5752 stats = rp->process_discovered_references(&is_alive,
5753 &keep_alive,
5754 &drain_queue,
5755 NULL,
5756 _gc_timer_stw);
5757 } else {
5758 // Parallel reference processing
5759 assert(rp->num_q() == no_of_gc_workers, "sanity");
5760 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5761
5762 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5763 stats = rp->process_discovered_references(&is_alive,
5764 &keep_alive,
5765 &drain_queue,
5766 &par_task_executor,
5767 _gc_timer_stw);
5768 }
5769
5770 _gc_tracer_stw->report_gc_reference_stats(stats);
5771 // We have completed copying any necessary live referent objects
5772 // (that were not copied during the actual pause) so we can
5773 // retire any active alloc buffers
5774 pss.retire_alloc_buffers();
5775 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5776
5777 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5778 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5779 }
5780
5781 // Weak Reference processing during an evacuation pause (part 2).
5782 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5783 double ref_enq_start = os::elapsedTime();
5784
5785 ReferenceProcessor* rp = _ref_processor_stw;
5786 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5787
5788 // Now enqueue any remaining on the discovered lists on to
5789 // the pending list.
5790 if (!rp->processing_is_mt()) {
5791 // Serial reference processing...
5792 rp->enqueue_discovered_references();
5793 } else {
5794 // Parallel reference enqueueing
5795
5796 assert(no_of_gc_workers == workers()->active_workers(),
5797 "Need to reset active workers");
5798 assert(rp->num_q() == no_of_gc_workers, "sanity");
5799 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5800
5801 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5802 rp->enqueue_discovered_references(&par_task_executor);
5803 }
5804
5805 rp->verify_no_references_recorded();
5806 assert(!rp->discovery_enabled(), "should have been disabled");
5807
5808 // FIXME
5809 // CM's reference processing also cleans up the string and symbol tables.
5810 // Should we do that here also? We could, but it is a serial operation
5811 // and could significantly increase the pause time.
5812
5813 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5814 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5815 }
5816
5817 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5818 _expand_heap_after_alloc_failure = true;
5819 _evacuation_failed = false;
5820
5821 // Should G1EvacuationFailureALot be in effect for this GC?
5822 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5823
5824 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5825
5826 // Disable the hot card cache.
5827 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5828 hot_card_cache->reset_hot_cache_claimed_index();
5829 hot_card_cache->set_use_cache(false);
5830
5831 uint n_workers;
5832 if (G1CollectedHeap::use_parallel_gc_threads()) {
5833 n_workers =
5834 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5835 workers()->active_workers(),
5836 Threads::number_of_non_daemon_threads());
5837 assert(UseDynamicNumberOfGCThreads ||
5838 n_workers == workers()->total_workers(),
5839 "If not dynamic should be using all the workers");
5840 workers()->set_active_workers(n_workers);
5841 set_par_threads(n_workers);
5842 } else {
5843 assert(n_par_threads() == 0,
5844 "Should be the original non-parallel value");
5845 n_workers = 1;
5846 }
5847
5848 G1ParTask g1_par_task(this, _task_queues);
5849
5850 init_for_evac_failure(NULL);
5851
5852 rem_set()->prepare_for_younger_refs_iterate(true);
5853
5854 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5855 double start_par_time_sec = os::elapsedTime();
5856 double end_par_time_sec;
5857
5858 {
5859 StrongRootsScope srs(this);
5860
5861 if (G1CollectedHeap::use_parallel_gc_threads()) {
5862 // The individual threads will set their evac-failure closures.
5863 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5864 // These tasks use ShareHeap::_process_strong_tasks
5865 assert(UseDynamicNumberOfGCThreads ||
5866 workers()->active_workers() == workers()->total_workers(),
5867 "If not dynamic should be using all the workers");
5868 workers()->run_task(&g1_par_task);
5869 } else {
5870 g1_par_task.set_for_termination(n_workers);
5871 g1_par_task.work(0);
5872 }
5873 end_par_time_sec = os::elapsedTime();
5874
5875 // Closing the inner scope will execute the destructor
5876 // for the StrongRootsScope object. We record the current
5877 // elapsed time before closing the scope so that time
5878 // taken for the SRS destructor is NOT included in the
5879 // reported parallel time.
5880 }
5881
5882 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5883 g1_policy()->phase_times()->record_par_time(par_time_ms);
5884
5885 double code_root_fixup_time_ms =
5886 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5887 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5888
5889 set_par_threads(0);
5890
5891 // Process any discovered reference objects - we have
5892 // to do this _before_ we retire the GC alloc regions
5893 // as we may have to copy some 'reachable' referent
5894 // objects (and their reachable sub-graphs) that were
5895 // not copied during the pause.
5896 process_discovered_references(n_workers);
5897
5898 // Weak root processing.
5899 {
5900 G1STWIsAliveClosure is_alive(this);
5901 G1KeepAliveClosure keep_alive(this);
5902 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5903 }
5904
5905 release_gc_alloc_regions(n_workers, evacuation_info);
5906 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5907
5908 // Reset and re-enable the hot card cache.
5909 // Note the counts for the cards in the regions in the
5910 // collection set are reset when the collection set is freed.
5911 hot_card_cache->reset_hot_cache();
5912 hot_card_cache->set_use_cache(true);
5913
5914 // Migrate the strong code roots attached to each region in
5915 // the collection set. Ideally we would like to do this
5916 // after we have finished the scanning/evacuation of the
5917 // strong code roots for a particular heap region.
5918 migrate_strong_code_roots();
5919
5920 if (g1_policy()->during_initial_mark_pause()) {
5921 // Reset the claim values set during marking the strong code roots
5922 reset_heap_region_claim_values();
5923 }
5924
5925 finalize_for_evac_failure();
5926
5927 if (evacuation_failed()) {
5928 remove_self_forwarding_pointers();
5929
5930 // Reset the G1EvacuationFailureALot counters and flags
5931 // Note: the values are reset only when an actual
5932 // evacuation failure occurs.
5933 NOT_PRODUCT(reset_evacuation_should_fail();)
5934 }
5935
5936 // Enqueue any remaining references remaining on the STW
5937 // reference processor's discovered lists. We need to do
5938 // this after the card table is cleaned (and verified) as
5939 // the act of enqueueing entries on to the pending list
5940 // will log these updates (and dirty their associated
5941 // cards). We need these updates logged to update any
5942 // RSets.
5943 enqueue_discovered_references(n_workers);
5944
5945 if (G1DeferredRSUpdate) {
5946 RedirtyLoggedCardTableEntryFastClosure redirty;
5947 dirty_card_queue_set().set_closure(&redirty);
5948 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5949
5950 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5951 dcq.merge_bufferlists(&dirty_card_queue_set());
5952 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5953 }
5954 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5955 }
5956
5957 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5958 size_t* pre_used,
5959 FreeRegionList* free_list,
5960 OldRegionSet* old_proxy_set,
5961 HumongousRegionSet* humongous_proxy_set,
5962 HRRSCleanupTask* hrrs_cleanup_task,
5963 bool par) {
5964 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5965 if (hr->isHumongous()) {
5966 assert(hr->startsHumongous(), "we should only see starts humongous");
5967 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5968 } else {
5969 _old_set.remove_with_proxy(hr, old_proxy_set);
5970 free_region(hr, pre_used, free_list, par);
5971 }
5972 } else {
5973 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5974 }
5975 }
5976
5977 void G1CollectedHeap::free_region(HeapRegion* hr,
5978 size_t* pre_used,
5979 FreeRegionList* free_list,
5980 bool par) {
5981 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5982 assert(!hr->is_empty(), "the region should not be empty");
5983 assert(free_list != NULL, "pre-condition");
5984
5985 // Clear the card counts for this region.
5986 // Note: we only need to do this if the region is not young
5987 // (since we don't refine cards in young regions).
5988 if (!hr->is_young()) {
5989 _cg1r->hot_card_cache()->reset_card_counts(hr);
5990 }
5991 *pre_used += hr->used();
5992 hr->hr_clear(par, true /* clear_space */);
5993 free_list->add_as_head(hr);
5994 }
5995
5996 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5997 size_t* pre_used,
5998 FreeRegionList* free_list,
5999 HumongousRegionSet* humongous_proxy_set,
6000 bool par) {
6001 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6002 assert(free_list != NULL, "pre-condition");
6003 assert(humongous_proxy_set != NULL, "pre-condition");
6004
6005 size_t hr_used = hr->used();
6006 size_t hr_capacity = hr->capacity();
6007 size_t hr_pre_used = 0;
6008 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
6009 // We need to read this before we make the region non-humongous,
6010 // otherwise the information will be gone.
6011 uint last_index = hr->last_hc_index();
6012 hr->set_notHumongous();
6013 free_region(hr, &hr_pre_used, free_list, par);
6014
6015 uint i = hr->hrs_index() + 1;
6016 while (i < last_index) {
6017 HeapRegion* curr_hr = region_at(i);
6018 assert(curr_hr->continuesHumongous(), "invariant");
6019 curr_hr->set_notHumongous();
6020 free_region(curr_hr, &hr_pre_used, free_list, par);
6021 i += 1;
6022 }
6023 assert(hr_pre_used == hr_used,
6024 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
6025 "should be the same", hr_pre_used, hr_used));
6026 *pre_used += hr_pre_used;
6027 }
6028
6029 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
6030 FreeRegionList* free_list,
6031 OldRegionSet* old_proxy_set,
6032 HumongousRegionSet* humongous_proxy_set,
6033 bool par) {
6034 if (pre_used > 0) {
6035 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
6036 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
6037 assert(_summary_bytes_used >= pre_used,
6038 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
6039 "should be >= pre_used: "SIZE_FORMAT,
6040 _summary_bytes_used, pre_used));
6041 _summary_bytes_used -= pre_used;
6042 }
6043 if (free_list != NULL && !free_list->is_empty()) {
6044 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6045 _free_list.add_as_head(free_list);
6046 }
6047 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
6048 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6049 _old_set.update_from_proxy(old_proxy_set);
6050 }
6051 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
6052 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6053 _humongous_set.update_from_proxy(humongous_proxy_set);
6054 }
6055 }
6056
6057 class G1ParCleanupCTTask : public AbstractGangTask {
6058 G1SATBCardTableModRefBS* _ct_bs;
6059 G1CollectedHeap* _g1h;
6060 HeapRegion* volatile _su_head;
6061 public:
6062 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6063 G1CollectedHeap* g1h) :
6064 AbstractGangTask("G1 Par Cleanup CT Task"),
6065 _ct_bs(ct_bs), _g1h(g1h) { }
6066
6067 void work(uint worker_id) {
6068 HeapRegion* r;
6069 while (r = _g1h->pop_dirty_cards_region()) {
6070 clear_cards(r);
6071 }
6072 }
6073
6074 void clear_cards(HeapRegion* r) {
6075 // Cards of the survivors should have already been dirtied.
6076 if (!r->is_survivor()) {
6077 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6078 }
6079 }
6080 };
6081
6082 #ifndef PRODUCT
6083 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6084 G1CollectedHeap* _g1h;
6085 G1SATBCardTableModRefBS* _ct_bs;
6086 public:
6087 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6088 : _g1h(g1h), _ct_bs(ct_bs) { }
6089 virtual bool doHeapRegion(HeapRegion* r) {
6090 if (r->is_survivor()) {
6091 _g1h->verify_dirty_region(r);
6092 } else {
6093 _g1h->verify_not_dirty_region(r);
6094 }
6095 return false;
6096 }
6097 };
6098
6099 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6100 // All of the region should be clean.
6101 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6102 MemRegion mr(hr->bottom(), hr->end());
6103 ct_bs->verify_not_dirty_region(mr);
6104 }
6105
6106 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6107 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6108 // dirty allocated blocks as they allocate them. The thread that
6109 // retires each region and replaces it with a new one will do a
6110 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6111 // not dirty that area (one less thing to have to do while holding
6112 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6113 // is dirty.
6114 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6115 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6116 if (hr->is_young()) {
6117 ct_bs->verify_g1_young_region(mr);
6118 } else {
6119 ct_bs->verify_dirty_region(mr);
6120 }
6121 }
6122
6123 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6124 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6125 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6126 verify_dirty_region(hr);
6127 }
6128 }
6129
6130 void G1CollectedHeap::verify_dirty_young_regions() {
6131 verify_dirty_young_list(_young_list->first_region());
6132 }
6133 #endif
6134
6135 void G1CollectedHeap::cleanUpCardTable() {
6136 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6137 double start = os::elapsedTime();
6138
6139 {
6140 // Iterate over the dirty cards region list.
6141 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6142
6143 if (G1CollectedHeap::use_parallel_gc_threads()) {
6144 set_par_threads();
6145 workers()->run_task(&cleanup_task);
6146 set_par_threads(0);
6147 } else {
6148 while (_dirty_cards_region_list) {
6149 HeapRegion* r = _dirty_cards_region_list;
6150 cleanup_task.clear_cards(r);
6151 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6152 if (_dirty_cards_region_list == r) {
6153 // The last region.
6154 _dirty_cards_region_list = NULL;
6155 }
6156 r->set_next_dirty_cards_region(NULL);
6157 }
6158 }
6159 #ifndef PRODUCT
6160 if (G1VerifyCTCleanup || VerifyAfterGC) {
6161 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6162 heap_region_iterate(&cleanup_verifier);
6163 }
6164 #endif
6165 }
6166
6167 double elapsed = os::elapsedTime() - start;
6168 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6169 }
6170
6171 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6172 size_t pre_used = 0;
6173 FreeRegionList local_free_list("Local List for CSet Freeing");
6174
6175 double young_time_ms = 0.0;
6176 double non_young_time_ms = 0.0;
6177
6178 // Since the collection set is a superset of the the young list,
6179 // all we need to do to clear the young list is clear its
6180 // head and length, and unlink any young regions in the code below
6181 _young_list->clear();
6182
6183 G1CollectorPolicy* policy = g1_policy();
6184
6185 double start_sec = os::elapsedTime();
6186 bool non_young = true;
6187
6188 HeapRegion* cur = cs_head;
6189 int age_bound = -1;
6190 size_t rs_lengths = 0;
6191
6192 while (cur != NULL) {
6193 assert(!is_on_master_free_list(cur), "sanity");
6194 if (non_young) {
6195 if (cur->is_young()) {
6196 double end_sec = os::elapsedTime();
6197 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6198 non_young_time_ms += elapsed_ms;
6199
6200 start_sec = os::elapsedTime();
6201 non_young = false;
6202 }
6203 } else {
6204 if (!cur->is_young()) {
6205 double end_sec = os::elapsedTime();
6206 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6207 young_time_ms += elapsed_ms;
6208
6209 start_sec = os::elapsedTime();
6210 non_young = true;
6211 }
6212 }
6213
6214 rs_lengths += cur->rem_set()->occupied();
6215
6216 HeapRegion* next = cur->next_in_collection_set();
6217 assert(cur->in_collection_set(), "bad CS");
6218 cur->set_next_in_collection_set(NULL);
6219 cur->set_in_collection_set(false);
6220
6221 if (cur->is_young()) {
6222 int index = cur->young_index_in_cset();
6223 assert(index != -1, "invariant");
6224 assert((uint) index < policy->young_cset_region_length(), "invariant");
6225 size_t words_survived = _surviving_young_words[index];
6226 cur->record_surv_words_in_group(words_survived);
6227
6228 // At this point the we have 'popped' cur from the collection set
6229 // (linked via next_in_collection_set()) but it is still in the
6230 // young list (linked via next_young_region()). Clear the
6231 // _next_young_region field.
6232 cur->set_next_young_region(NULL);
6233 } else {
6234 int index = cur->young_index_in_cset();
6235 assert(index == -1, "invariant");
6236 }
6237
6238 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6239 (!cur->is_young() && cur->young_index_in_cset() == -1),
6240 "invariant" );
6241
6242 if (!cur->evacuation_failed()) {
6243 MemRegion used_mr = cur->used_region();
6244
6245 // And the region is empty.
6246 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6247 free_region(cur, &pre_used, &local_free_list, false /* par */);
6248 } else {
6249 cur->uninstall_surv_rate_group();
6250 if (cur->is_young()) {
6251 cur->set_young_index_in_cset(-1);
6252 }
6253 cur->set_not_young();
6254 cur->set_evacuation_failed(false);
6255 // The region is now considered to be old.
6256 _old_set.add(cur);
6257 evacuation_info.increment_collectionset_used_after(cur->used());
6258 }
6259 cur = next;
6260 }
6261
6262 evacuation_info.set_regions_freed(local_free_list.length());
6263 policy->record_max_rs_lengths(rs_lengths);
6264 policy->cset_regions_freed();
6265
6266 double end_sec = os::elapsedTime();
6267 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6268
6269 if (non_young) {
6270 non_young_time_ms += elapsed_ms;
6271 } else {
6272 young_time_ms += elapsed_ms;
6273 }
6274
6275 update_sets_after_freeing_regions(pre_used, &local_free_list,
6276 NULL /* old_proxy_set */,
6277 NULL /* humongous_proxy_set */,
6278 false /* par */);
6279 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6280 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6281 }
6282
6283 // This routine is similar to the above but does not record
6284 // any policy statistics or update free lists; we are abandoning
6285 // the current incremental collection set in preparation of a
6286 // full collection. After the full GC we will start to build up
6287 // the incremental collection set again.
6288 // This is only called when we're doing a full collection
6289 // and is immediately followed by the tearing down of the young list.
6290
6291 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6292 HeapRegion* cur = cs_head;
6293
6294 while (cur != NULL) {
6295 HeapRegion* next = cur->next_in_collection_set();
6296 assert(cur->in_collection_set(), "bad CS");
6297 cur->set_next_in_collection_set(NULL);
6298 cur->set_in_collection_set(false);
6299 cur->set_young_index_in_cset(-1);
6300 cur = next;
6301 }
6302 }
6303
6304 void G1CollectedHeap::set_free_regions_coming() {
6305 if (G1ConcRegionFreeingVerbose) {
6306 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6307 "setting free regions coming");
6308 }
6309
6310 assert(!free_regions_coming(), "pre-condition");
6311 _free_regions_coming = true;
6312 }
6313
6314 void G1CollectedHeap::reset_free_regions_coming() {
6315 assert(free_regions_coming(), "pre-condition");
6316
6317 {
6318 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6319 _free_regions_coming = false;
6320 SecondaryFreeList_lock->notify_all();
6321 }
6322
6323 if (G1ConcRegionFreeingVerbose) {
6324 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6325 "reset free regions coming");
6326 }
6327 }
6328
6329 void G1CollectedHeap::wait_while_free_regions_coming() {
6330 // Most of the time we won't have to wait, so let's do a quick test
6331 // first before we take the lock.
6332 if (!free_regions_coming()) {
6333 return;
6334 }
6335
6336 if (G1ConcRegionFreeingVerbose) {
6337 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6338 "waiting for free regions");
6339 }
6340
6341 {
6342 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6343 while (free_regions_coming()) {
6344 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6345 }
6346 }
6347
6348 if (G1ConcRegionFreeingVerbose) {
6349 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6350 "done waiting for free regions");
6351 }
6352 }
6353
6354 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6355 assert(heap_lock_held_for_gc(),
6356 "the heap lock should already be held by or for this thread");
6357 _young_list->push_region(hr);
6358 }
6359
6360 class NoYoungRegionsClosure: public HeapRegionClosure {
6361 private:
6362 bool _success;
6363 public:
6364 NoYoungRegionsClosure() : _success(true) { }
6365 bool doHeapRegion(HeapRegion* r) {
6366 if (r->is_young()) {
6367 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6368 r->bottom(), r->end());
6369 _success = false;
6370 }
6371 return false;
6372 }
6373 bool success() { return _success; }
6374 };
6375
6376 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6377 bool ret = _young_list->check_list_empty(check_sample);
6378
6379 if (check_heap) {
6380 NoYoungRegionsClosure closure;
6381 heap_region_iterate(&closure);
6382 ret = ret && closure.success();
6383 }
6384
6385 return ret;
6386 }
6387
6388 class TearDownRegionSetsClosure : public HeapRegionClosure {
6389 private:
6390 OldRegionSet *_old_set;
6391
6392 public:
6393 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6394
6395 bool doHeapRegion(HeapRegion* r) {
6396 if (r->is_empty()) {
6397 // We ignore empty regions, we'll empty the free list afterwards
6398 } else if (r->is_young()) {
6399 // We ignore young regions, we'll empty the young list afterwards
6400 } else if (r->isHumongous()) {
6401 // We ignore humongous regions, we're not tearing down the
6402 // humongous region set
6403 } else {
6404 // The rest should be old
6405 _old_set->remove(r);
6406 }
6407 return false;
6408 }
6409
6410 ~TearDownRegionSetsClosure() {
6411 assert(_old_set->is_empty(), "post-condition");
6412 }
6413 };
6414
6415 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6416 assert_at_safepoint(true /* should_be_vm_thread */);
6417
6418 if (!free_list_only) {
6419 TearDownRegionSetsClosure cl(&_old_set);
6420 heap_region_iterate(&cl);
6421
6422 // Need to do this after the heap iteration to be able to
6423 // recognize the young regions and ignore them during the iteration.
6424 _young_list->empty_list();
6425 }
6426 _free_list.remove_all();
6427 }
6428
6429 class RebuildRegionSetsClosure : public HeapRegionClosure {
6430 private:
6431 bool _free_list_only;
6432 OldRegionSet* _old_set;
6433 FreeRegionList* _free_list;
6434 size_t _total_used;
6435
6436 public:
6437 RebuildRegionSetsClosure(bool free_list_only,
6438 OldRegionSet* old_set, FreeRegionList* free_list) :
6439 _free_list_only(free_list_only),
6440 _old_set(old_set), _free_list(free_list), _total_used(0) {
6441 assert(_free_list->is_empty(), "pre-condition");
6442 if (!free_list_only) {
6443 assert(_old_set->is_empty(), "pre-condition");
6444 }
6445 }
6446
6447 bool doHeapRegion(HeapRegion* r) {
6448 if (r->continuesHumongous()) {
6449 return false;
6450 }
6451
6452 if (r->is_empty()) {
6453 // Add free regions to the free list
6454 _free_list->add_as_tail(r);
6455 } else if (!_free_list_only) {
6456 assert(!r->is_young(), "we should not come across young regions");
6457
6458 if (r->isHumongous()) {
6459 // We ignore humongous regions, we left the humongous set unchanged
6460 } else {
6461 // The rest should be old, add them to the old set
6462 _old_set->add(r);
6463 }
6464 _total_used += r->used();
6465 }
6466
6467 return false;
6468 }
6469
6470 size_t total_used() {
6471 return _total_used;
6472 }
6473 };
6474
6475 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6476 assert_at_safepoint(true /* should_be_vm_thread */);
6477
6478 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6479 heap_region_iterate(&cl);
6480
6481 if (!free_list_only) {
6482 _summary_bytes_used = cl.total_used();
6483 }
6484 assert(_summary_bytes_used == recalculate_used(),
6485 err_msg("inconsistent _summary_bytes_used, "
6486 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6487 _summary_bytes_used, recalculate_used()));
6488 }
6489
6490 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6491 _refine_cte_cl->set_concurrent(concurrent);
6492 }
6493
6494 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6495 HeapRegion* hr = heap_region_containing(p);
6496 if (hr == NULL) {
6497 return is_in_permanent(p);
6498 } else {
6499 return hr->is_in(p);
6500 }
6501 }
6502
6503 // Methods for the mutator alloc region
6504
6505 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6506 bool force) {
6507 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6508 assert(!force || g1_policy()->can_expand_young_list(),
6509 "if force is true we should be able to expand the young list");
6510 bool young_list_full = g1_policy()->is_young_list_full();
6511 if (force || !young_list_full) {
6512 HeapRegion* new_alloc_region = new_region(word_size,
6513 false /* do_expand */);
6514 if (new_alloc_region != NULL) {
6515 set_region_short_lived_locked(new_alloc_region);
6516 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6517 return new_alloc_region;
6518 }
6519 }
6520 return NULL;
6521 }
6522
6523 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6524 size_t allocated_bytes) {
6525 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6526 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6527
6528 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6529 _summary_bytes_used += allocated_bytes;
6530 _hr_printer.retire(alloc_region);
6531 // We update the eden sizes here, when the region is retired,
6532 // instead of when it's allocated, since this is the point that its
6533 // used space has been recored in _summary_bytes_used.
6534 g1mm()->update_eden_size();
6535 }
6536
6537 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6538 bool force) {
6539 return _g1h->new_mutator_alloc_region(word_size, force);
6540 }
6541
6542 void G1CollectedHeap::set_par_threads() {
6543 // Don't change the number of workers. Use the value previously set
6544 // in the workgroup.
6545 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6546 uint n_workers = workers()->active_workers();
6547 assert(UseDynamicNumberOfGCThreads ||
6548 n_workers == workers()->total_workers(),
6549 "Otherwise should be using the total number of workers");
6550 if (n_workers == 0) {
6551 assert(false, "Should have been set in prior evacuation pause.");
6552 n_workers = ParallelGCThreads;
6553 workers()->set_active_workers(n_workers);
6554 }
6555 set_par_threads(n_workers);
6556 }
6557
6558 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6559 size_t allocated_bytes) {
6560 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6561 }
6562
6563 // Methods for the GC alloc regions
6564
6565 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6566 uint count,
6567 GCAllocPurpose ap) {
6568 assert(FreeList_lock->owned_by_self(), "pre-condition");
6569
6570 if (count < g1_policy()->max_regions(ap)) {
6571 HeapRegion* new_alloc_region = new_region(word_size,
6572 true /* do_expand */);
6573 if (new_alloc_region != NULL) {
6574 // We really only need to do this for old regions given that we
6575 // should never scan survivors. But it doesn't hurt to do it
6576 // for survivors too.
6577 new_alloc_region->set_saved_mark();
6578 if (ap == GCAllocForSurvived) {
6579 new_alloc_region->set_survivor();
6580 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6581 } else {
6582 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6583 }
6584 bool during_im = g1_policy()->during_initial_mark_pause();
6585 new_alloc_region->note_start_of_copying(during_im);
6586 return new_alloc_region;
6587 } else {
6588 g1_policy()->note_alloc_region_limit_reached(ap);
6589 }
6590 }
6591 return NULL;
6592 }
6593
6594 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6595 size_t allocated_bytes,
6596 GCAllocPurpose ap) {
6597 bool during_im = g1_policy()->during_initial_mark_pause();
6598 alloc_region->note_end_of_copying(during_im);
6599 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6600 if (ap == GCAllocForSurvived) {
6601 young_list()->add_survivor_region(alloc_region);
6602 } else {
6603 _old_set.add(alloc_region);
6604 }
6605 _hr_printer.retire(alloc_region);
6606 }
6607
6608 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6609 bool force) {
6610 assert(!force, "not supported for GC alloc regions");
6611 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6612 }
6613
6614 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6615 size_t allocated_bytes) {
6616 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6617 GCAllocForSurvived);
6618 }
6619
6620 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6621 bool force) {
6622 assert(!force, "not supported for GC alloc regions");
6623 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6624 }
6625
6626 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6627 size_t allocated_bytes) {
6628 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6629 GCAllocForTenured);
6630 }
6631 // Heap region set verification
6632
6633 class VerifyRegionListsClosure : public HeapRegionClosure {
6634 private:
6635 FreeRegionList* _free_list;
6636 OldRegionSet* _old_set;
6637 HumongousRegionSet* _humongous_set;
6638 uint _region_count;
6639
6640 public:
6641 VerifyRegionListsClosure(OldRegionSet* old_set,
6642 HumongousRegionSet* humongous_set,
6643 FreeRegionList* free_list) :
6644 _old_set(old_set), _humongous_set(humongous_set),
6645 _free_list(free_list), _region_count(0) { }
6646
6647 uint region_count() { return _region_count; }
6648
6649 bool doHeapRegion(HeapRegion* hr) {
6650 _region_count += 1;
6651
6652 if (hr->continuesHumongous()) {
6653 return false;
6654 }
6655
6656 if (hr->is_young()) {
6657 // TODO
6658 } else if (hr->startsHumongous()) {
6659 _humongous_set->verify_next_region(hr);
6660 } else if (hr->is_empty()) {
6661 _free_list->verify_next_region(hr);
6662 } else {
6663 _old_set->verify_next_region(hr);
6664 }
6665 return false;
6666 }
6667 };
6668
6669 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6670 HeapWord* bottom) {
6671 HeapWord* end = bottom + HeapRegion::GrainWords;
6672 MemRegion mr(bottom, end);
6673 assert(_g1_reserved.contains(mr), "invariant");
6674 // This might return NULL if the allocation fails
6675 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6676 }
6677
6678 void G1CollectedHeap::verify_region_sets() {
6679 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6680
6681 // First, check the explicit lists.
6682 _free_list.verify();
6683 {
6684 // Given that a concurrent operation might be adding regions to
6685 // the secondary free list we have to take the lock before
6686 // verifying it.
6687 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6688 _secondary_free_list.verify();
6689 }
6690 _old_set.verify();
6691 _humongous_set.verify();
6692
6693 // If a concurrent region freeing operation is in progress it will
6694 // be difficult to correctly attributed any free regions we come
6695 // across to the correct free list given that they might belong to
6696 // one of several (free_list, secondary_free_list, any local lists,
6697 // etc.). So, if that's the case we will skip the rest of the
6698 // verification operation. Alternatively, waiting for the concurrent
6699 // operation to complete will have a non-trivial effect on the GC's
6700 // operation (no concurrent operation will last longer than the
6701 // interval between two calls to verification) and it might hide
6702 // any issues that we would like to catch during testing.
6703 if (free_regions_coming()) {
6704 return;
6705 }
6706
6707 // Make sure we append the secondary_free_list on the free_list so
6708 // that all free regions we will come across can be safely
6709 // attributed to the free_list.
6710 append_secondary_free_list_if_not_empty_with_lock();
6711
6712 // Finally, make sure that the region accounting in the lists is
6713 // consistent with what we see in the heap.
6714 _old_set.verify_start();
6715 _humongous_set.verify_start();
6716 _free_list.verify_start();
6717
6718 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6719 heap_region_iterate(&cl);
6720
6721 _old_set.verify_end();
6722 _humongous_set.verify_end();
6723 _free_list.verify_end();
6724 }
6725
6726 // Optimized nmethod scanning
6727
6728 class RegisterNMethodOopClosure: public OopClosure {
6729 G1CollectedHeap* _g1h;
6730 nmethod* _nm;
6731
6732 template <class T> void do_oop_work(T* p) {
6733 T heap_oop = oopDesc::load_heap_oop(p);
6734 if (!oopDesc::is_null(heap_oop)) {
6735 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6736 HeapRegion* hr = _g1h->heap_region_containing(obj);
6737 if (hr == NULL) {
6738 // reference into perm gen - ignore.
6739 assert(_g1h->is_in_permanent(obj), "must be a reference into perm gen");
6740 return;
6741 }
6742 assert(!hr->continuesHumongous(),
6743 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6744 " starting at "HR_FORMAT,
6745 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6746
6747 // HeapRegion::add_strong_code_root() avoids adding duplicate
6748 // entries but having duplicates is OK since we "mark" nmethods
6749 // as visited when we scan the strong code root lists during the GC.
6750 hr->add_strong_code_root(_nm);
6751 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6752 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6753 _nm, HR_FORMAT_PARAMS(hr)));
6754 }
6755 }
6756
6757 public:
6758 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6759 _g1h(g1h), _nm(nm) {}
6760
6761 void do_oop(oop* p) { do_oop_work(p); }
6762 void do_oop(narrowOop* p) { do_oop_work(p); }
6763 };
6764
6765 class UnregisterNMethodOopClosure: public OopClosure {
6766 G1CollectedHeap* _g1h;
6767 nmethod* _nm;
6768
6769 template <class T> void do_oop_work(T* p) {
6770 T heap_oop = oopDesc::load_heap_oop(p);
6771 if (!oopDesc::is_null(heap_oop)) {
6772 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6773 HeapRegion* hr = _g1h->heap_region_containing(obj);
6774 if (hr == NULL) {
6775 // reference into perm gen - ignore.
6776 assert(_g1h->is_in_permanent(obj), "must be a reference into perm gen");
6777 return;
6778 }
6779 assert(!hr->continuesHumongous(),
6780 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6781 " starting at "HR_FORMAT,
6782 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6783
6784 hr->remove_strong_code_root(_nm);
6785 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6786 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6787 _nm, HR_FORMAT_PARAMS(hr))); }
6788 }
6789
6790 public:
6791 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6792 _g1h(g1h), _nm(nm) {}
6793
6794 void do_oop(oop* p) { do_oop_work(p); }
6795 void do_oop(narrowOop* p) { do_oop_work(p); }
6796 };
6797
6798 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6799 CollectedHeap::register_nmethod(nm);
6800
6801 guarantee(nm != NULL, "sanity");
6802 RegisterNMethodOopClosure reg_cl(this, nm);
6803 nm->oops_do(®_cl);
6804 }
6805
6806 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6807 CollectedHeap::unregister_nmethod(nm);
6808
6809 guarantee(nm != NULL, "sanity");
6810 UnregisterNMethodOopClosure reg_cl(this, nm);
6811 nm->oops_do(®_cl, false, true);
6812 }
6813
6814 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6815 public:
6816 bool doHeapRegion(HeapRegion *hr) {
6817 assert(!hr->isHumongous(),
6818 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6819 HR_FORMAT_PARAMS(hr)));
6820 hr->migrate_strong_code_roots();
6821 return false;
6822 }
6823 };
6824
6825 void G1CollectedHeap::migrate_strong_code_roots() {
6826 MigrateCodeRootsHeapRegionClosure cl;
6827 double migrate_start = os::elapsedTime();
6828 collection_set_iterate(&cl);
6829 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6830 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6831 }
6832
6833 // Mark all the code roots that point into regions *not* in the
6834 // collection set.
6835 //
6836 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6837 // walking the the code roots lists of regions not in the collection
6838 // set. Suppose we have an nmethod (M) that points to objects in two
6839 // separate regions - one in the collection set (R1) and one not (R2).
6840 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6841 // nmethod M when walking the code roots for R1. When we come to scan
6842 // the code roots for R2, we would see that M is already marked and it
6843 // would be skipped and the objects in R2 that are referenced from M
6844 // would not be evacuated.
6845
6846 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6847
6848 class MarkStrongCodeRootOopClosure: public OopClosure {
6849 ConcurrentMark* _cm;
6850 HeapRegion* _hr;
6851 uint _worker_id;
6852
6853 template <class T> void do_oop_work(T* p) {
6854 T heap_oop = oopDesc::load_heap_oop(p);
6855 if (!oopDesc::is_null(heap_oop)) {
6856 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6857 // Only mark objects in the region (which is assumed
6858 // to be not in the collection set).
6859 if (_hr->is_in(obj)) {
6860 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6861 }
6862 }
6863 }
6864
6865 public:
6866 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6867 _cm(cm), _hr(hr), _worker_id(worker_id) {
6868 assert(!_hr->in_collection_set(), "sanity");
6869 }
6870
6871 void do_oop(narrowOop* p) { do_oop_work(p); }
6872 void do_oop(oop* p) { do_oop_work(p); }
6873 };
6874
6875 MarkStrongCodeRootOopClosure _oop_cl;
6876
6877 public:
6878 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6879 _oop_cl(cm, hr, worker_id) {}
6880
6881 void do_code_blob(CodeBlob* cb) {
6882 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6883 if (nm != NULL) {
6884 nm->oops_do(&_oop_cl);
6885 }
6886 }
6887 };
6888
6889 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6890 G1CollectedHeap* _g1h;
6891 uint _worker_id;
6892
6893 public:
6894 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6895 _g1h(g1h), _worker_id(worker_id) {}
6896
6897 bool doHeapRegion(HeapRegion *hr) {
6898 HeapRegionRemSet* hrrs = hr->rem_set();
6899 if (hr->continuesHumongous()) {
6900 // Code roots should never be attached to a continuation of a humongous region
6901 assert(hrrs->strong_code_roots_list_length() == 0,
6902 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6903 " starting at "HR_FORMAT", but has "INT32_FORMAT,
6904 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6905 hrrs->strong_code_roots_list_length()));
6906 return false;
6907 }
6908
6909 if (hr->in_collection_set()) {
6910 // Don't mark code roots into regions in the collection set here.
6911 // They will be marked when we scan them.
6912 return false;
6913 }
6914
6915 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6916 hr->strong_code_roots_do(&cb_cl);
6917 return false;
6918 }
6919 };
6920
6921 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6922 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6923 if (G1CollectedHeap::use_parallel_gc_threads()) {
6924 heap_region_par_iterate_chunked(&cl,
6925 worker_id,
6926 workers()->active_workers(),
6927 HeapRegion::ParMarkRootClaimValue);
6928 } else {
6929 heap_region_iterate(&cl);
6930 }
6931 }
6932
6933 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6934 G1CollectedHeap* _g1h;
6935
6936 public:
6937 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6938 _g1h(g1h) {}
6939
6940 void do_code_blob(CodeBlob* cb) {
6941 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6942 if (nm == NULL) {
6943 return;
6944 }
6945
6946 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6947 _g1h->register_nmethod(nm);
6948 }
6949 }
6950 };
6951
6952 void G1CollectedHeap::rebuild_strong_code_roots() {
6953 RebuildStrongCodeRootClosure blob_cl(this);
6954 CodeCache::blobs_do(&blob_cl);
6955 }