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/vmThread.hpp"
59 #include "utilities/ticks.hpp"
60
61 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
62
63 // turn it on so that the contents of the young list (scan-only /
64 // to-be-collected) are printed at "strategic" points before / during
65 // / after the collection --- this is useful for debugging
66 #define YOUNG_LIST_VERBOSE 0
67 // CURRENT STATUS
68 // This file is under construction. Search for "FIXME".
69
70 // INVARIANTS/NOTES
71 //
72 // All allocation activity covered by the G1CollectedHeap interface is
73 // serialized by acquiring the HeapLock. This happens in mem_allocate
74 // and allocate_new_tlab, which are the "entry" points to the
75 // allocation code from the rest of the JVM. (Note that this does not
76 // apply to TLAB allocation, which is not part of this interface: it
77 // is done by clients of this interface.)
78
79 // Notes on implementation of parallelism in different tasks.
80 //
81 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
82 // The number of GC workers is passed to heap_region_par_iterate_chunked().
83 // It does use run_task() which sets _n_workers in the task.
84 // G1ParTask executes g1_process_strong_roots() ->
85 // SharedHeap::process_strong_roots() which calls eventually to
86 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
87 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
88 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
89 //
90
91 // Local to this file.
92
93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
94 SuspendibleThreadSet* _sts;
95 G1RemSet* _g1rs;
96 ConcurrentG1Refine* _cg1r;
97 bool _concurrent;
98 public:
99 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
100 G1RemSet* g1rs,
101 ConcurrentG1Refine* cg1r) :
102 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
103 {}
104 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
105 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
106 // This path is executed by the concurrent refine or mutator threads,
107 // concurrently, and so we do not care if card_ptr contains references
108 // that point into the collection set.
109 assert(!oops_into_cset, "should be");
110
111 if (_concurrent && _sts->should_yield()) {
112 // Caller will actually yield.
113 return false;
114 }
115 // Otherwise, we finished successfully; return true.
116 return true;
117 }
118 void set_concurrent(bool b) { _concurrent = b; }
119 };
120
121
122 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
123 int _calls;
124 G1CollectedHeap* _g1h;
125 CardTableModRefBS* _ctbs;
126 int _histo[256];
127 public:
128 ClearLoggedCardTableEntryClosure() :
129 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
130 {
131 for (int i = 0; i < 256; i++) _histo[i] = 0;
132 }
133 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
134 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
135 _calls++;
136 unsigned char* ujb = (unsigned char*)card_ptr;
137 int ind = (int)(*ujb);
138 _histo[ind]++;
139 *card_ptr = -1;
140 }
141 return true;
142 }
143 int calls() { return _calls; }
144 void print_histo() {
145 gclog_or_tty->print_cr("Card table value histogram:");
146 for (int i = 0; i < 256; i++) {
147 if (_histo[i] != 0) {
148 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
149 }
150 }
151 }
152 };
153
154 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
155 int _calls;
156 G1CollectedHeap* _g1h;
157 CardTableModRefBS* _ctbs;
158 public:
159 RedirtyLoggedCardTableEntryClosure() :
160 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
161
162 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
163 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
164 _calls++;
165 *card_ptr = 0;
166 }
167 return true;
168 }
169 int calls() { return _calls; }
170 };
171
172 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
173 public:
174 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
175 *card_ptr = CardTableModRefBS::dirty_card_val();
176 return true;
177 }
178 };
179
180 YoungList::YoungList(G1CollectedHeap* g1h) :
181 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
182 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
183 guarantee(check_list_empty(false), "just making sure...");
184 }
185
186 void YoungList::push_region(HeapRegion *hr) {
187 assert(!hr->is_young(), "should not already be young");
188 assert(hr->get_next_young_region() == NULL, "cause it should!");
189
190 hr->set_next_young_region(_head);
191 _head = hr;
192
193 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
194 ++_length;
195 }
196
197 void YoungList::add_survivor_region(HeapRegion* hr) {
198 assert(hr->is_survivor(), "should be flagged as survivor region");
199 assert(hr->get_next_young_region() == NULL, "cause it should!");
200
201 hr->set_next_young_region(_survivor_head);
202 if (_survivor_head == NULL) {
203 _survivor_tail = hr;
204 }
205 _survivor_head = hr;
206 ++_survivor_length;
207 }
208
209 void YoungList::empty_list(HeapRegion* list) {
210 while (list != NULL) {
211 HeapRegion* next = list->get_next_young_region();
212 list->set_next_young_region(NULL);
213 list->uninstall_surv_rate_group();
214 list->set_not_young();
215 list = next;
216 }
217 }
218
219 void YoungList::empty_list() {
220 assert(check_list_well_formed(), "young list should be well formed");
221
222 empty_list(_head);
223 _head = NULL;
224 _length = 0;
225
226 empty_list(_survivor_head);
227 _survivor_head = NULL;
228 _survivor_tail = NULL;
229 _survivor_length = 0;
230
231 _last_sampled_rs_lengths = 0;
232
233 assert(check_list_empty(false), "just making sure...");
234 }
235
236 bool YoungList::check_list_well_formed() {
237 bool ret = true;
238
239 uint length = 0;
240 HeapRegion* curr = _head;
241 HeapRegion* last = NULL;
242 while (curr != NULL) {
243 if (!curr->is_young()) {
244 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
245 "incorrectly tagged (y: %d, surv: %d)",
246 curr->bottom(), curr->end(),
247 curr->is_young(), curr->is_survivor());
248 ret = false;
249 }
250 ++length;
251 last = curr;
252 curr = curr->get_next_young_region();
253 }
254 ret = ret && (length == _length);
255
256 if (!ret) {
257 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
258 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
259 length, _length);
260 }
261
262 return ret;
263 }
264
265 bool YoungList::check_list_empty(bool check_sample) {
266 bool ret = true;
267
268 if (_length != 0) {
269 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
270 _length);
271 ret = false;
272 }
273 if (check_sample && _last_sampled_rs_lengths != 0) {
274 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
275 ret = false;
276 }
277 if (_head != NULL) {
278 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
279 ret = false;
280 }
281 if (!ret) {
282 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
283 }
284
285 return ret;
286 }
287
288 void
289 YoungList::rs_length_sampling_init() {
290 _sampled_rs_lengths = 0;
291 _curr = _head;
292 }
293
294 bool
295 YoungList::rs_length_sampling_more() {
296 return _curr != NULL;
297 }
298
299 void
300 YoungList::rs_length_sampling_next() {
301 assert( _curr != NULL, "invariant" );
302 size_t rs_length = _curr->rem_set()->occupied();
303
304 _sampled_rs_lengths += rs_length;
305
306 // The current region may not yet have been added to the
307 // incremental collection set (it gets added when it is
308 // retired as the current allocation region).
309 if (_curr->in_collection_set()) {
310 // Update the collection set policy information for this region
311 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
312 }
313
314 _curr = _curr->get_next_young_region();
315 if (_curr == NULL) {
316 _last_sampled_rs_lengths = _sampled_rs_lengths;
317 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
318 }
319 }
320
321 void
322 YoungList::reset_auxilary_lists() {
323 guarantee( is_empty(), "young list should be empty" );
324 assert(check_list_well_formed(), "young list should be well formed");
325
326 // Add survivor regions to SurvRateGroup.
327 _g1h->g1_policy()->note_start_adding_survivor_regions();
328 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
329
330 int young_index_in_cset = 0;
331 for (HeapRegion* curr = _survivor_head;
332 curr != NULL;
333 curr = curr->get_next_young_region()) {
334 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
335
336 // The region is a non-empty survivor so let's add it to
337 // the incremental collection set for the next evacuation
338 // pause.
339 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
340 young_index_in_cset += 1;
341 }
342 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
343 _g1h->g1_policy()->note_stop_adding_survivor_regions();
344
345 _head = _survivor_head;
346 _length = _survivor_length;
347 if (_survivor_head != NULL) {
348 assert(_survivor_tail != NULL, "cause it shouldn't be");
349 assert(_survivor_length > 0, "invariant");
350 _survivor_tail->set_next_young_region(NULL);
351 }
352
353 // Don't clear the survivor list handles until the start of
354 // the next evacuation pause - we need it in order to re-tag
355 // the survivor regions from this evacuation pause as 'young'
356 // at the start of the next.
357
358 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
359
360 assert(check_list_well_formed(), "young list should be well formed");
361 }
362
363 void YoungList::print() {
364 HeapRegion* lists[] = {_head, _survivor_head};
365 const char* names[] = {"YOUNG", "SURVIVOR"};
366
367 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
368 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
369 HeapRegion *curr = lists[list];
370 if (curr == NULL)
371 gclog_or_tty->print_cr(" empty");
372 while (curr != NULL) {
373 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
374 HR_FORMAT_PARAMS(curr),
375 curr->prev_top_at_mark_start(),
376 curr->next_top_at_mark_start(),
377 curr->age_in_surv_rate_group_cond());
378 curr = curr->get_next_young_region();
379 }
380 }
381
382 gclog_or_tty->print_cr("");
383 }
384
385 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
386 {
387 // Claim the right to put the region on the dirty cards region list
388 // by installing a self pointer.
389 HeapRegion* next = hr->get_next_dirty_cards_region();
390 if (next == NULL) {
391 HeapRegion* res = (HeapRegion*)
392 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
393 NULL);
394 if (res == NULL) {
395 HeapRegion* head;
396 do {
397 // Put the region to the dirty cards region list.
398 head = _dirty_cards_region_list;
399 next = (HeapRegion*)
400 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
401 if (next == head) {
402 assert(hr->get_next_dirty_cards_region() == hr,
403 "hr->get_next_dirty_cards_region() != hr");
404 if (next == NULL) {
405 // The last region in the list points to itself.
406 hr->set_next_dirty_cards_region(hr);
407 } else {
408 hr->set_next_dirty_cards_region(next);
409 }
410 }
411 } while (next != head);
412 }
413 }
414 }
415
416 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
417 {
418 HeapRegion* head;
419 HeapRegion* hr;
420 do {
421 head = _dirty_cards_region_list;
422 if (head == NULL) {
423 return NULL;
424 }
425 HeapRegion* new_head = head->get_next_dirty_cards_region();
426 if (head == new_head) {
427 // The last region.
428 new_head = NULL;
429 }
430 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
431 head);
432 } while (hr != head);
433 assert(hr != NULL, "invariant");
434 hr->set_next_dirty_cards_region(NULL);
435 return hr;
436 }
437
438 void G1CollectedHeap::stop_conc_gc_threads() {
439 _cg1r->stop();
440 _cmThread->stop();
441 }
442
443 #ifdef ASSERT
444 // A region is added to the collection set as it is retired
445 // so an address p can point to a region which will be in the
446 // collection set but has not yet been retired. This method
447 // therefore is only accurate during a GC pause after all
448 // regions have been retired. It is used for debugging
449 // to check if an nmethod has references to objects that can
450 // be move during a partial collection. Though it can be
451 // inaccurate, it is sufficient for G1 because the conservative
452 // implementation of is_scavengable() for G1 will indicate that
453 // all nmethods must be scanned during a partial collection.
454 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
455 HeapRegion* hr = heap_region_containing(p);
456 return hr != NULL && hr->in_collection_set();
457 }
458 #endif
459
460 // Returns true if the reference points to an object that
461 // can move in an incremental collection.
462 bool G1CollectedHeap::is_scavengable(const void* p) {
463 G1CollectedHeap* g1h = G1CollectedHeap::heap();
464 G1CollectorPolicy* g1p = g1h->g1_policy();
465 HeapRegion* hr = heap_region_containing(p);
466 if (hr == NULL) {
467 // null
468 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
469 return false;
470 } else {
471 return !hr->isHumongous();
472 }
473 }
474
475 void G1CollectedHeap::check_ct_logs_at_safepoint() {
476 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
477 CardTableModRefBS* ct_bs = g1_barrier_set();
478
479 // Count the dirty cards at the start.
480 CountNonCleanMemRegionClosure count1(this);
481 ct_bs->mod_card_iterate(&count1);
482 int orig_count = count1.n();
483
484 // First clear the logged cards.
485 ClearLoggedCardTableEntryClosure clear;
486 dcqs.set_closure(&clear);
487 dcqs.apply_closure_to_all_completed_buffers();
488 dcqs.iterate_closure_all_threads(false);
489 clear.print_histo();
490
491 // Now ensure that there's no dirty cards.
492 CountNonCleanMemRegionClosure count2(this);
493 ct_bs->mod_card_iterate(&count2);
494 if (count2.n() != 0) {
495 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
496 count2.n(), orig_count);
497 }
498 guarantee(count2.n() == 0, "Card table should be clean.");
499
500 RedirtyLoggedCardTableEntryClosure redirty;
501 JavaThread::dirty_card_queue_set().set_closure(&redirty);
502 dcqs.apply_closure_to_all_completed_buffers();
503 dcqs.iterate_closure_all_threads(false);
504 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
505 clear.calls(), orig_count);
506 guarantee(redirty.calls() == clear.calls(),
507 "Or else mechanism is broken.");
508
509 CountNonCleanMemRegionClosure count3(this);
510 ct_bs->mod_card_iterate(&count3);
511 if (count3.n() != orig_count) {
512 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
513 orig_count, count3.n());
514 guarantee(count3.n() >= orig_count, "Should have restored them all.");
515 }
516
517 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
518 }
519
520 // Private class members.
521
522 G1CollectedHeap* G1CollectedHeap::_g1h;
523
524 // Private methods.
525
526 HeapRegion*
527 G1CollectedHeap::new_region_try_secondary_free_list() {
528 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
529 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
530 if (!_secondary_free_list.is_empty()) {
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "secondary_free_list has %u entries",
534 _secondary_free_list.length());
535 }
536 // It looks as if there are free regions available on the
537 // secondary_free_list. Let's move them to the free_list and try
538 // again to allocate from it.
539 append_secondary_free_list();
540
541 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
542 "empty we should have moved at least one entry to the free_list");
543 HeapRegion* res = _free_list.remove_head();
544 if (G1ConcRegionFreeingVerbose) {
545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
546 "allocated "HR_FORMAT" from secondary_free_list",
547 HR_FORMAT_PARAMS(res));
548 }
549 return res;
550 }
551
552 // Wait here until we get notified either when (a) there are no
553 // more free regions coming or (b) some regions have been moved on
554 // the secondary_free_list.
555 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
556 }
557
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "could not allocate from secondary_free_list");
561 }
562 return NULL;
563 }
564
565 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
566 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
567 "the only time we use this to allocate a humongous region is "
568 "when we are allocating a single humongous region");
569
570 HeapRegion* res;
571 if (G1StressConcRegionFreeing) {
572 if (!_secondary_free_list.is_empty()) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "forced to look at the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list();
578 if (res != NULL) {
579 return res;
580 }
581 }
582 }
583 res = _free_list.remove_head_or_null();
584 if (res == NULL) {
585 if (G1ConcRegionFreeingVerbose) {
586 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
587 "res == NULL, trying the secondary_free_list");
588 }
589 res = new_region_try_secondary_free_list();
590 }
591 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
592 // Currently, only attempts to allocate GC alloc regions set
593 // do_expand to true. So, we should only reach here during a
594 // safepoint. If this assumption changes we might have to
595 // reconsider the use of _expand_heap_after_alloc_failure.
596 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
597
598 ergo_verbose1(ErgoHeapSizing,
599 "attempt heap expansion",
600 ergo_format_reason("region allocation request failed")
601 ergo_format_byte("allocation request"),
602 word_size * HeapWordSize);
603 if (expand(word_size * HeapWordSize)) {
604 // Given that expand() succeeded in expanding the heap, and we
605 // always expand the heap by an amount aligned to the heap
606 // region size, the free list should in theory not be empty. So
607 // it would probably be OK to use remove_head(). But the extra
608 // check for NULL is unlikely to be a performance issue here (we
609 // just expanded the heap!) so let's just be conservative and
610 // use remove_head_or_null().
611 res = _free_list.remove_head_or_null();
612 } else {
613 _expand_heap_after_alloc_failure = false;
614 }
615 }
616 return res;
617 }
618
619 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
620 size_t word_size) {
621 assert(isHumongous(word_size), "word_size should be humongous");
622 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
623
624 uint first = G1_NULL_HRS_INDEX;
625 if (num_regions == 1) {
626 // Only one region to allocate, no need to go through the slower
627 // path. The caller will attempt the expansion if this fails, so
628 // let's not try to expand here too.
629 HeapRegion* hr = new_region(word_size, false /* do_expand */);
630 if (hr != NULL) {
631 first = hr->hrs_index();
632 } else {
633 first = G1_NULL_HRS_INDEX;
634 }
635 } else {
636 // We can't allocate humongous regions while cleanupComplete() is
637 // running, since some of the regions we find to be empty might not
638 // yet be added to the free list and it is not straightforward to
639 // know which list they are on so that we can remove them. Note
640 // that we only need to do this if we need to allocate more than
641 // one region to satisfy the current humongous allocation
642 // request. If we are only allocating one region we use the common
643 // region allocation code (see above).
644 wait_while_free_regions_coming();
645 append_secondary_free_list_if_not_empty_with_lock();
646
647 if (free_regions() >= num_regions) {
648 first = _hrs.find_contiguous(num_regions);
649 if (first != G1_NULL_HRS_INDEX) {
650 for (uint i = first; i < first + num_regions; ++i) {
651 HeapRegion* hr = region_at(i);
652 assert(hr->is_empty(), "sanity");
653 assert(is_on_master_free_list(hr), "sanity");
654 hr->set_pending_removal(true);
655 }
656 _free_list.remove_all_pending(num_regions);
657 }
658 }
659 }
660 return first;
661 }
662
663 HeapWord*
664 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
665 uint num_regions,
666 size_t word_size) {
667 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
668 assert(isHumongous(word_size), "word_size should be humongous");
669 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
670
671 // Index of last region in the series + 1.
672 uint last = first + num_regions;
673
674 // We need to initialize the region(s) we just discovered. This is
675 // a bit tricky given that it can happen concurrently with
676 // refinement threads refining cards on these regions and
677 // potentially wanting to refine the BOT as they are scanning
678 // those cards (this can happen shortly after a cleanup; see CR
679 // 6991377). So we have to set up the region(s) carefully and in
680 // a specific order.
681
682 // The word size sum of all the regions we will allocate.
683 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
684 assert(word_size <= word_size_sum, "sanity");
685
686 // This will be the "starts humongous" region.
687 HeapRegion* first_hr = region_at(first);
688 // The header of the new object will be placed at the bottom of
689 // the first region.
690 HeapWord* new_obj = first_hr->bottom();
691 // This will be the new end of the first region in the series that
692 // should also match the end of the last region in the series.
693 HeapWord* new_end = new_obj + word_size_sum;
694 // This will be the new top of the first region that will reflect
695 // this allocation.
696 HeapWord* new_top = new_obj + word_size;
697
698 // First, we need to zero the header of the space that we will be
699 // allocating. When we update top further down, some refinement
700 // threads might try to scan the region. By zeroing the header we
701 // ensure that any thread that will try to scan the region will
702 // come across the zero klass word and bail out.
703 //
704 // NOTE: It would not have been correct to have used
705 // CollectedHeap::fill_with_object() and make the space look like
706 // an int array. The thread that is doing the allocation will
707 // later update the object header to a potentially different array
708 // type and, for a very short period of time, the klass and length
709 // fields will be inconsistent. This could cause a refinement
710 // thread to calculate the object size incorrectly.
711 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
712
713 // We will set up the first region as "starts humongous". This
714 // will also update the BOT covering all the regions to reflect
715 // that there is a single object that starts at the bottom of the
716 // first region.
717 first_hr->set_startsHumongous(new_top, new_end);
718
719 // Then, if there are any, we will set up the "continues
720 // humongous" regions.
721 HeapRegion* hr = NULL;
722 for (uint i = first + 1; i < last; ++i) {
723 hr = region_at(i);
724 hr->set_continuesHumongous(first_hr);
725 }
726 // If we have "continues humongous" regions (hr != NULL), then the
727 // end of the last one should match new_end.
728 assert(hr == NULL || hr->end() == new_end, "sanity");
729
730 // Up to this point no concurrent thread would have been able to
731 // do any scanning on any region in this series. All the top
732 // fields still point to bottom, so the intersection between
733 // [bottom,top] and [card_start,card_end] will be empty. Before we
734 // update the top fields, we'll do a storestore to make sure that
735 // no thread sees the update to top before the zeroing of the
736 // object header and the BOT initialization.
737 OrderAccess::storestore();
738
739 // Now that the BOT and the object header have been initialized,
740 // we can update top of the "starts humongous" region.
741 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
742 "new_top should be in this region");
743 first_hr->set_top(new_top);
744 if (_hr_printer.is_active()) {
745 HeapWord* bottom = first_hr->bottom();
746 HeapWord* end = first_hr->orig_end();
747 if ((first + 1) == last) {
748 // the series has a single humongous region
749 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
750 } else {
751 // the series has more than one humongous regions
752 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
753 }
754 }
755
756 // Now, we will update the top fields of the "continues humongous"
757 // regions. The reason we need to do this is that, otherwise,
758 // these regions would look empty and this will confuse parts of
759 // G1. For example, the code that looks for a consecutive number
760 // of empty regions will consider them empty and try to
761 // re-allocate them. We can extend is_empty() to also include
762 // !continuesHumongous(), but it is easier to just update the top
763 // fields here. The way we set top for all regions (i.e., top ==
764 // end for all regions but the last one, top == new_top for the
765 // last one) is actually used when we will free up the humongous
766 // region in free_humongous_region().
767 hr = NULL;
768 for (uint i = first + 1; i < last; ++i) {
769 hr = region_at(i);
770 if ((i + 1) == last) {
771 // last continues humongous region
772 assert(hr->bottom() < new_top && new_top <= hr->end(),
773 "new_top should fall on this region");
774 hr->set_top(new_top);
775 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
776 } else {
777 // not last one
778 assert(new_top > hr->end(), "new_top should be above this region");
779 hr->set_top(hr->end());
780 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
781 }
782 }
783 // If we have continues humongous regions (hr != NULL), then the
784 // end of the last one should match new_end and its top should
785 // match new_top.
786 assert(hr == NULL ||
787 (hr->end() == new_end && hr->top() == new_top), "sanity");
788
789 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
790 _summary_bytes_used += first_hr->used();
791 _humongous_set.add(first_hr);
792
793 return new_obj;
794 }
795
796 // If could fit into free regions w/o expansion, try.
797 // Otherwise, if can expand, do so.
798 // Otherwise, if using ex regions might help, try with ex given back.
799 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
800 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
801
802 verify_region_sets_optional();
803
804 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
805 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
806 uint x_num = expansion_regions();
807 uint fs = _hrs.free_suffix();
808 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
809 if (first == G1_NULL_HRS_INDEX) {
810 // The only thing we can do now is attempt expansion.
811 if (fs + x_num >= num_regions) {
812 // If the number of regions we're trying to allocate for this
813 // object is at most the number of regions in the free suffix,
814 // then the call to humongous_obj_allocate_find_first() above
815 // should have succeeded and we wouldn't be here.
816 //
817 // We should only be trying to expand when the free suffix is
818 // not sufficient for the object _and_ we have some expansion
819 // room available.
820 assert(num_regions > fs, "earlier allocation should have succeeded");
821
822 ergo_verbose1(ErgoHeapSizing,
823 "attempt heap expansion",
824 ergo_format_reason("humongous allocation request failed")
825 ergo_format_byte("allocation request"),
826 word_size * HeapWordSize);
827 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
828 // Even though the heap was expanded, it might not have
829 // reached the desired size. So, we cannot assume that the
830 // allocation will succeed.
831 first = humongous_obj_allocate_find_first(num_regions, word_size);
832 }
833 }
834 }
835
836 HeapWord* result = NULL;
837 if (first != G1_NULL_HRS_INDEX) {
838 result =
839 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
840 assert(result != NULL, "it should always return a valid result");
841
842 // A successful humongous object allocation changes the used space
843 // information of the old generation so we need to recalculate the
844 // sizes and update the jstat counters here.
845 g1mm()->update_sizes();
846 }
847
848 verify_region_sets_optional();
849
850 return result;
851 }
852
853 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
856
857 unsigned int dummy_gc_count_before;
858 int dummy_gclocker_retry_count = 0;
859 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
860 }
861
862 HeapWord*
863 G1CollectedHeap::mem_allocate(size_t word_size,
864 bool* gc_overhead_limit_was_exceeded) {
865 assert_heap_not_locked_and_not_at_safepoint();
866
867 // Loop until the allocation is satisfied, or unsatisfied after GC.
868 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
869 unsigned int gc_count_before;
870
871 HeapWord* result = NULL;
872 if (!isHumongous(word_size)) {
873 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
874 } else {
875 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
876 }
877 if (result != NULL) {
878 return result;
879 }
880
881 // Create the garbage collection operation...
882 VM_G1CollectForAllocation op(gc_count_before, word_size);
883 // ...and get the VM thread to execute it.
884 VMThread::execute(&op);
885
886 if (op.prologue_succeeded() && op.pause_succeeded()) {
887 // If the operation was successful we'll return the result even
888 // if it is NULL. If the allocation attempt failed immediately
889 // after a Full GC, it's unlikely we'll be able to allocate now.
890 HeapWord* result = op.result();
891 if (result != NULL && !isHumongous(word_size)) {
892 // Allocations that take place on VM operations do not do any
893 // card dirtying and we have to do it here. We only have to do
894 // this for non-humongous allocations, though.
895 dirty_young_block(result, word_size);
896 }
897 return result;
898 } else {
899 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
900 return NULL;
901 }
902 assert(op.result() == NULL,
903 "the result should be NULL if the VM op did not succeed");
904 }
905
906 // Give a warning if we seem to be looping forever.
907 if ((QueuedAllocationWarningCount > 0) &&
908 (try_count % QueuedAllocationWarningCount == 0)) {
909 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
910 }
911 }
912
913 ShouldNotReachHere();
914 return NULL;
915 }
916
917 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
918 unsigned int *gc_count_before_ret,
919 int* gclocker_retry_count_ret) {
920 // Make sure you read the note in attempt_allocation_humongous().
921
922 assert_heap_not_locked_and_not_at_safepoint();
923 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
924 "be called for humongous allocation requests");
925
926 // We should only get here after the first-level allocation attempt
927 // (attempt_allocation()) failed to allocate.
928
929 // We will loop until a) we manage to successfully perform the
930 // allocation or b) we successfully schedule a collection which
931 // fails to perform the allocation. b) is the only case when we'll
932 // return NULL.
933 HeapWord* result = NULL;
934 for (int try_count = 1; /* we'll return */; try_count += 1) {
935 bool should_try_gc;
936 unsigned int gc_count_before;
937
938 {
939 MutexLockerEx x(Heap_lock);
940
941 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
942 false /* bot_updates */);
943 if (result != NULL) {
944 return result;
945 }
946
947 // If we reach here, attempt_allocation_locked() above failed to
948 // allocate a new region. So the mutator alloc region should be NULL.
949 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
950
951 if (GC_locker::is_active_and_needs_gc()) {
952 if (g1_policy()->can_expand_young_list()) {
953 // No need for an ergo verbose message here,
954 // can_expand_young_list() does this when it returns true.
955 result = _mutator_alloc_region.attempt_allocation_force(word_size,
956 false /* bot_updates */);
957 if (result != NULL) {
958 return result;
959 }
960 }
961 should_try_gc = false;
962 } else {
963 // The GCLocker may not be active but the GCLocker initiated
964 // GC may not yet have been performed (GCLocker::needs_gc()
965 // returns true). In this case we do not try this GC and
966 // wait until the GCLocker initiated GC is performed, and
967 // then retry the allocation.
968 if (GC_locker::needs_gc()) {
969 should_try_gc = false;
970 } else {
971 // Read the GC count while still holding the Heap_lock.
972 gc_count_before = total_collections();
973 should_try_gc = true;
974 }
975 }
976 }
977
978 if (should_try_gc) {
979 bool succeeded;
980 result = do_collection_pause(word_size, gc_count_before, &succeeded,
981 GCCause::_g1_inc_collection_pause);
982 if (result != NULL) {
983 assert(succeeded, "only way to get back a non-NULL result");
984 return result;
985 }
986
987 if (succeeded) {
988 // If we get here we successfully scheduled a collection which
989 // failed to allocate. No point in trying to allocate
990 // further. We'll just return NULL.
991 MutexLockerEx x(Heap_lock);
992 *gc_count_before_ret = total_collections();
993 return NULL;
994 }
995 } else {
996 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
997 MutexLockerEx x(Heap_lock);
998 *gc_count_before_ret = total_collections();
999 return NULL;
1000 }
1001 // The GCLocker is either active or the GCLocker initiated
1002 // GC has not yet been performed. Stall until it is and
1003 // then retry the allocation.
1004 GC_locker::stall_until_clear();
1005 (*gclocker_retry_count_ret) += 1;
1006 }
1007
1008 // We can reach here if we were unsuccessful in scheduling a
1009 // collection (because another thread beat us to it) or if we were
1010 // stalled due to the GC locker. In either can we should retry the
1011 // allocation attempt in case another thread successfully
1012 // performed a collection and reclaimed enough space. We do the
1013 // first attempt (without holding the Heap_lock) here and the
1014 // follow-on attempt will be at the start of the next loop
1015 // iteration (after taking the Heap_lock).
1016 result = _mutator_alloc_region.attempt_allocation(word_size,
1017 false /* bot_updates */);
1018 if (result != NULL) {
1019 return result;
1020 }
1021
1022 // Give a warning if we seem to be looping forever.
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_slow() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1035 unsigned int * gc_count_before_ret,
1036 int* gclocker_retry_count_ret) {
1037 // The structure of this method has a lot of similarities to
1038 // attempt_allocation_slow(). The reason these two were not merged
1039 // into a single one is that such a method would require several "if
1040 // allocation is not humongous do this, otherwise do that"
1041 // conditional paths which would obscure its flow. In fact, an early
1042 // version of this code did use a unified method which was harder to
1043 // follow and, as a result, it had subtle bugs that were hard to
1044 // track down. So keeping these two methods separate allows each to
1045 // be more readable. It will be good to keep these two in sync as
1046 // much as possible.
1047
1048 assert_heap_not_locked_and_not_at_safepoint();
1049 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1050 "should only be called for humongous allocations");
1051
1052 // Humongous objects can exhaust the heap quickly, so we should check if we
1053 // need to start a marking cycle at each humongous object allocation. We do
1054 // the check before we do the actual allocation. The reason for doing it
1055 // before the allocation is that we avoid having to keep track of the newly
1056 // allocated memory while we do a GC.
1057 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1058 word_size)) {
1059 collect(GCCause::_g1_humongous_allocation);
1060 }
1061
1062 // We will loop until a) we manage to successfully perform the
1063 // allocation or b) we successfully schedule a collection which
1064 // fails to perform the allocation. b) is the only case when we'll
1065 // return NULL.
1066 HeapWord* result = NULL;
1067 for (int try_count = 1; /* we'll return */; try_count += 1) {
1068 bool should_try_gc;
1069 unsigned int gc_count_before;
1070
1071 {
1072 MutexLockerEx x(Heap_lock);
1073
1074 // Given that humongous objects are not allocated in young
1075 // regions, we'll first try to do the allocation without doing a
1076 // collection hoping that there's enough space in the heap.
1077 result = humongous_obj_allocate(word_size);
1078 if (result != NULL) {
1079 return result;
1080 }
1081
1082 if (GC_locker::is_active_and_needs_gc()) {
1083 should_try_gc = false;
1084 } else {
1085 // The GCLocker may not be active but the GCLocker initiated
1086 // GC may not yet have been performed (GCLocker::needs_gc()
1087 // returns true). In this case we do not try this GC and
1088 // wait until the GCLocker initiated GC is performed, and
1089 // then retry the allocation.
1090 if (GC_locker::needs_gc()) {
1091 should_try_gc = false;
1092 } else {
1093 // Read the GC count while still holding the Heap_lock.
1094 gc_count_before = total_collections();
1095 should_try_gc = true;
1096 }
1097 }
1098 }
1099
1100 if (should_try_gc) {
1101 // If we failed to allocate the humongous object, we should try to
1102 // do a collection pause (if we're allowed) in case it reclaims
1103 // enough space for the allocation to succeed after the pause.
1104
1105 bool succeeded;
1106 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1107 GCCause::_g1_humongous_allocation);
1108 if (result != NULL) {
1109 assert(succeeded, "only way to get back a non-NULL result");
1110 return result;
1111 }
1112
1113 if (succeeded) {
1114 // If we get here we successfully scheduled a collection which
1115 // failed to allocate. No point in trying to allocate
1116 // further. We'll just return NULL.
1117 MutexLockerEx x(Heap_lock);
1118 *gc_count_before_ret = total_collections();
1119 return NULL;
1120 }
1121 } else {
1122 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1123 MutexLockerEx x(Heap_lock);
1124 *gc_count_before_ret = total_collections();
1125 return NULL;
1126 }
1127 // The GCLocker is either active or the GCLocker initiated
1128 // GC has not yet been performed. Stall until it is and
1129 // then retry the allocation.
1130 GC_locker::stall_until_clear();
1131 (*gclocker_retry_count_ret) += 1;
1132 }
1133
1134 // We can reach here if we were unsuccessful in scheduling a
1135 // collection (because another thread beat us to it) or if we were
1136 // stalled due to the GC locker. In either can we should retry the
1137 // allocation attempt in case another thread successfully
1138 // performed a collection and reclaimed enough space. Give a
1139 // warning if we seem to be looping forever.
1140
1141 if ((QueuedAllocationWarningCount > 0) &&
1142 (try_count % QueuedAllocationWarningCount == 0)) {
1143 warning("G1CollectedHeap::attempt_allocation_humongous() "
1144 "retries %d times", try_count);
1145 }
1146 }
1147
1148 ShouldNotReachHere();
1149 return NULL;
1150 }
1151
1152 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1153 bool expect_null_mutator_alloc_region) {
1154 assert_at_safepoint(true /* should_be_vm_thread */);
1155 assert(_mutator_alloc_region.get() == NULL ||
1156 !expect_null_mutator_alloc_region,
1157 "the current alloc region was unexpectedly found to be non-NULL");
1158
1159 if (!isHumongous(word_size)) {
1160 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1161 false /* bot_updates */);
1162 } else {
1163 HeapWord* result = humongous_obj_allocate(word_size);
1164 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1165 g1_policy()->set_initiate_conc_mark_if_possible();
1166 }
1167 return result;
1168 }
1169
1170 ShouldNotReachHere();
1171 }
1172
1173 class PostMCRemSetClearClosure: public HeapRegionClosure {
1174 G1CollectedHeap* _g1h;
1175 ModRefBarrierSet* _mr_bs;
1176 public:
1177 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1178 _g1h(g1h), _mr_bs(mr_bs) {}
1179
1180 bool doHeapRegion(HeapRegion* r) {
1181 HeapRegionRemSet* hrrs = r->rem_set();
1182
1183 if (r->continuesHumongous()) {
1184 // We'll assert that the strong code root list and RSet is empty
1185 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1186 assert(hrrs->occupied() == 0, "RSet should be empty");
1187 return false;
1188 }
1189
1190 _g1h->reset_gc_time_stamps(r);
1191 hrrs->clear();
1192 // You might think here that we could clear just the cards
1193 // corresponding to the used region. But no: if we leave a dirty card
1194 // in a region we might allocate into, then it would prevent that card
1195 // from being enqueued, and cause it to be missed.
1196 // Re: the performance cost: we shouldn't be doing full GC anyway!
1197 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1198
1199 return false;
1200 }
1201 };
1202
1203 void G1CollectedHeap::clear_rsets_post_compaction() {
1204 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1205 heap_region_iterate(&rs_clear);
1206 }
1207
1208 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1209 G1CollectedHeap* _g1h;
1210 UpdateRSOopClosure _cl;
1211 int _worker_i;
1212 public:
1213 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1214 _cl(g1->g1_rem_set(), worker_i),
1215 _worker_i(worker_i),
1216 _g1h(g1)
1217 { }
1218
1219 bool doHeapRegion(HeapRegion* r) {
1220 if (!r->continuesHumongous()) {
1221 _cl.set_from(r);
1222 r->oop_iterate(&_cl);
1223 }
1224 return false;
1225 }
1226 };
1227
1228 class ParRebuildRSTask: public AbstractGangTask {
1229 G1CollectedHeap* _g1;
1230 public:
1231 ParRebuildRSTask(G1CollectedHeap* g1)
1232 : AbstractGangTask("ParRebuildRSTask"),
1233 _g1(g1)
1234 { }
1235
1236 void work(uint worker_id) {
1237 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1238 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1239 _g1->workers()->active_workers(),
1240 HeapRegion::RebuildRSClaimValue);
1241 }
1242 };
1243
1244 class PostCompactionPrinterClosure: public HeapRegionClosure {
1245 private:
1246 G1HRPrinter* _hr_printer;
1247 public:
1248 bool doHeapRegion(HeapRegion* hr) {
1249 assert(!hr->is_young(), "not expecting to find young regions");
1250 // We only generate output for non-empty regions.
1251 if (!hr->is_empty()) {
1252 if (!hr->isHumongous()) {
1253 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1254 } else if (hr->startsHumongous()) {
1255 if (hr->region_num() == 1) {
1256 // single humongous region
1257 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1258 } else {
1259 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1260 }
1261 } else {
1262 assert(hr->continuesHumongous(), "only way to get here");
1263 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1264 }
1265 }
1266 return false;
1267 }
1268
1269 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1270 : _hr_printer(hr_printer) { }
1271 };
1272
1273 void G1CollectedHeap::print_hrs_post_compaction() {
1274 PostCompactionPrinterClosure cl(hr_printer());
1275 heap_region_iterate(&cl);
1276 }
1277
1278 bool G1CollectedHeap::do_collection(bool explicit_gc,
1279 bool clear_all_soft_refs,
1280 size_t word_size) {
1281 assert_at_safepoint(true /* should_be_vm_thread */);
1282
1283 if (GC_locker::check_active_before_gc()) {
1284 return false;
1285 }
1286
1287 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1288 gc_timer->register_gc_start();
1289
1290 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1291 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1292
1293 SvcGCMarker sgcm(SvcGCMarker::FULL);
1294 ResourceMark rm;
1295
1296 print_heap_before_gc();
1297 trace_heap_before_gc(gc_tracer);
1298
1299 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1300
1301 HRSPhaseSetter x(HRSPhaseFullGC);
1302 verify_region_sets_optional();
1303
1304 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1305 collector_policy()->should_clear_all_soft_refs();
1306
1307 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1308
1309 {
1310 IsGCActiveMark x;
1311
1312 // Timing
1313 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1314 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1315 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1316
1317 {
1318 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL);
1319 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1320 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1321
1322 double start = os::elapsedTime();
1323 g1_policy()->record_full_collection_start();
1324
1325 // Note: When we have a more flexible GC logging framework that
1326 // allows us to add optional attributes to a GC log record we
1327 // could consider timing and reporting how long we wait in the
1328 // following two methods.
1329 wait_while_free_regions_coming();
1330 // If we start the compaction before the CM threads finish
1331 // scanning the root regions we might trip them over as we'll
1332 // be moving objects / updating references. So let's wait until
1333 // they are done. By telling them to abort, they should complete
1334 // early.
1335 _cm->root_regions()->abort();
1336 _cm->root_regions()->wait_until_scan_finished();
1337 append_secondary_free_list_if_not_empty_with_lock();
1338
1339 gc_prologue(true);
1340 increment_total_collections(true /* full gc */);
1341 increment_old_marking_cycles_started();
1342
1343 assert(used() == recalculate_used(), "Should be equal");
1344
1345 verify_before_gc();
1346
1347 pre_full_gc_dump(gc_timer);
1348
1349 COMPILER2_PRESENT(DerivedPointerTable::clear());
1350
1351 // Disable discovery and empty the discovered lists
1352 // for the CM ref processor.
1353 ref_processor_cm()->disable_discovery();
1354 ref_processor_cm()->abandon_partial_discovery();
1355 ref_processor_cm()->verify_no_references_recorded();
1356
1357 // Abandon current iterations of concurrent marking and concurrent
1358 // refinement, if any are in progress. We have to do this before
1359 // wait_until_scan_finished() below.
1360 concurrent_mark()->abort();
1361
1362 // Make sure we'll choose a new allocation region afterwards.
1363 release_mutator_alloc_region();
1364 abandon_gc_alloc_regions();
1365 g1_rem_set()->cleanupHRRS();
1366
1367 // We should call this after we retire any currently active alloc
1368 // regions so that all the ALLOC / RETIRE events are generated
1369 // before the start GC event.
1370 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1371
1372 // We may have added regions to the current incremental collection
1373 // set between the last GC or pause and now. We need to clear the
1374 // incremental collection set and then start rebuilding it afresh
1375 // after this full GC.
1376 abandon_collection_set(g1_policy()->inc_cset_head());
1377 g1_policy()->clear_incremental_cset();
1378 g1_policy()->stop_incremental_cset_building();
1379
1380 tear_down_region_sets(false /* free_list_only */);
1381 g1_policy()->set_gcs_are_young(true);
1382
1383 // See the comments in g1CollectedHeap.hpp and
1384 // G1CollectedHeap::ref_processing_init() about
1385 // how reference processing currently works in G1.
1386
1387 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1388 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1389
1390 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1391 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1392
1393 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1394 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1395
1396 // Do collection work
1397 {
1398 HandleMark hm; // Discard invalid handles created during gc
1399 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1400 }
1401
1402 assert(free_regions() == 0, "we should not have added any free regions");
1403 rebuild_region_sets(false /* free_list_only */);
1404
1405 // Enqueue any discovered reference objects that have
1406 // not been removed from the discovered lists.
1407 ref_processor_stw()->enqueue_discovered_references();
1408
1409 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1410
1411 MemoryService::track_memory_usage();
1412
1413 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1414 ref_processor_stw()->verify_no_references_recorded();
1415
1416 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1417 ClassLoaderDataGraph::purge();
1418 MetaspaceAux::verify_metrics();
1419
1420 // Note: since we've just done a full GC, concurrent
1421 // marking is no longer active. Therefore we need not
1422 // re-enable reference discovery for the CM ref processor.
1423 // That will be done at the start of the next marking cycle.
1424 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1425 ref_processor_cm()->verify_no_references_recorded();
1426
1427 reset_gc_time_stamp();
1428 // Since everything potentially moved, we will clear all remembered
1429 // sets, and clear all cards. Later we will rebuild remembered
1430 // sets. We will also reset the GC time stamps of the regions.
1431 clear_rsets_post_compaction();
1432 check_gc_time_stamps();
1433
1434 // Resize the heap if necessary.
1435 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1436
1437 if (_hr_printer.is_active()) {
1438 // We should do this after we potentially resize the heap so
1439 // that all the COMMIT / UNCOMMIT events are generated before
1440 // the end GC event.
1441
1442 print_hrs_post_compaction();
1443 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1444 }
1445
1446 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1447 if (hot_card_cache->use_cache()) {
1448 hot_card_cache->reset_card_counts();
1449 hot_card_cache->reset_hot_cache();
1450 }
1451
1452 // Rebuild remembered sets of all regions.
1453 if (G1CollectedHeap::use_parallel_gc_threads()) {
1454 uint n_workers =
1455 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1456 workers()->active_workers(),
1457 Threads::number_of_non_daemon_threads());
1458 assert(UseDynamicNumberOfGCThreads ||
1459 n_workers == workers()->total_workers(),
1460 "If not dynamic should be using all the workers");
1461 workers()->set_active_workers(n_workers);
1462 // Set parallel threads in the heap (_n_par_threads) only
1463 // before a parallel phase and always reset it to 0 after
1464 // the phase so that the number of parallel threads does
1465 // no get carried forward to a serial phase where there
1466 // may be code that is "possibly_parallel".
1467 set_par_threads(n_workers);
1468
1469 ParRebuildRSTask rebuild_rs_task(this);
1470 assert(check_heap_region_claim_values(
1471 HeapRegion::InitialClaimValue), "sanity check");
1472 assert(UseDynamicNumberOfGCThreads ||
1473 workers()->active_workers() == workers()->total_workers(),
1474 "Unless dynamic should use total workers");
1475 // Use the most recent number of active workers
1476 assert(workers()->active_workers() > 0,
1477 "Active workers not properly set");
1478 set_par_threads(workers()->active_workers());
1479 workers()->run_task(&rebuild_rs_task);
1480 set_par_threads(0);
1481 assert(check_heap_region_claim_values(
1482 HeapRegion::RebuildRSClaimValue), "sanity check");
1483 reset_heap_region_claim_values();
1484 } else {
1485 RebuildRSOutOfRegionClosure rebuild_rs(this);
1486 heap_region_iterate(&rebuild_rs);
1487 }
1488
1489 // Rebuild the strong code root lists for each region
1490 rebuild_strong_code_roots();
1491
1492 if (true) { // FIXME
1493 MetaspaceGC::compute_new_size();
1494 }
1495
1496 #ifdef TRACESPINNING
1497 ParallelTaskTerminator::print_termination_counts();
1498 #endif
1499
1500 // Discard all rset updates
1501 JavaThread::dirty_card_queue_set().abandon_logs();
1502 assert(!G1DeferredRSUpdate
1503 || (G1DeferredRSUpdate &&
1504 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1505
1506 _young_list->reset_sampled_info();
1507 // At this point there should be no regions in the
1508 // entire heap tagged as young.
1509 assert(check_young_list_empty(true /* check_heap */),
1510 "young list should be empty at this point");
1511
1512 // Update the number of full collections that have been completed.
1513 increment_old_marking_cycles_completed(false /* concurrent */);
1514
1515 _hrs.verify_optional();
1516 verify_region_sets_optional();
1517
1518 verify_after_gc();
1519
1520 // Start a new incremental collection set for the next pause
1521 assert(g1_policy()->collection_set() == NULL, "must be");
1522 g1_policy()->start_incremental_cset_building();
1523
1524 // Clear the _cset_fast_test bitmap in anticipation of adding
1525 // regions to the incremental collection set for the next
1526 // evacuation pause.
1527 clear_cset_fast_test();
1528
1529 init_mutator_alloc_region();
1530
1531 double end = os::elapsedTime();
1532 g1_policy()->record_full_collection_end();
1533
1534 if (G1Log::fine()) {
1535 g1_policy()->print_heap_transition();
1536 }
1537
1538 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1539 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1540 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1541 // before any GC notifications are raised.
1542 g1mm()->update_sizes();
1543
1544 gc_epilogue(true);
1545 }
1546
1547 if (G1Log::finer()) {
1548 g1_policy()->print_detailed_heap_transition(true /* full */);
1549 }
1550
1551 print_heap_after_gc();
1552 trace_heap_after_gc(gc_tracer);
1553
1554 post_full_gc_dump(gc_timer);
1555
1556 gc_timer->register_gc_end();
1557 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1558 }
1559
1560 return true;
1561 }
1562
1563 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1564 // do_collection() will return whether it succeeded in performing
1565 // the GC. Currently, there is no facility on the
1566 // do_full_collection() API to notify the caller than the collection
1567 // did not succeed (e.g., because it was locked out by the GC
1568 // locker). So, right now, we'll ignore the return value.
1569 bool dummy = do_collection(true, /* explicit_gc */
1570 clear_all_soft_refs,
1571 0 /* word_size */);
1572 }
1573
1574 // This code is mostly copied from TenuredGeneration.
1575 void
1576 G1CollectedHeap::
1577 resize_if_necessary_after_full_collection(size_t word_size) {
1578 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1579
1580 // Include the current allocation, if any, and bytes that will be
1581 // pre-allocated to support collections, as "used".
1582 const size_t used_after_gc = used();
1583 const size_t capacity_after_gc = capacity();
1584 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1585
1586 // This is enforced in arguments.cpp.
1587 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1588 "otherwise the code below doesn't make sense");
1589
1590 // We don't have floating point command-line arguments
1591 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1592 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1593 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1594 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1595
1596 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1597 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1598
1599 // We have to be careful here as these two calculations can overflow
1600 // 32-bit size_t's.
1601 double used_after_gc_d = (double) used_after_gc;
1602 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1603 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1604
1605 // Let's make sure that they are both under the max heap size, which
1606 // by default will make them fit into a size_t.
1607 double desired_capacity_upper_bound = (double) max_heap_size;
1608 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1609 desired_capacity_upper_bound);
1610 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1611 desired_capacity_upper_bound);
1612
1613 // We can now safely turn them into size_t's.
1614 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1615 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1616
1617 // This assert only makes sense here, before we adjust them
1618 // with respect to the min and max heap size.
1619 assert(minimum_desired_capacity <= maximum_desired_capacity,
1620 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1621 "maximum_desired_capacity = "SIZE_FORMAT,
1622 minimum_desired_capacity, maximum_desired_capacity));
1623
1624 // Should not be greater than the heap max size. No need to adjust
1625 // it with respect to the heap min size as it's a lower bound (i.e.,
1626 // we'll try to make the capacity larger than it, not smaller).
1627 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1628 // Should not be less than the heap min size. No need to adjust it
1629 // with respect to the heap max size as it's an upper bound (i.e.,
1630 // we'll try to make the capacity smaller than it, not greater).
1631 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1632
1633 if (capacity_after_gc < minimum_desired_capacity) {
1634 // Don't expand unless it's significant
1635 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1636 ergo_verbose4(ErgoHeapSizing,
1637 "attempt heap expansion",
1638 ergo_format_reason("capacity lower than "
1639 "min desired capacity after Full GC")
1640 ergo_format_byte("capacity")
1641 ergo_format_byte("occupancy")
1642 ergo_format_byte_perc("min desired capacity"),
1643 capacity_after_gc, used_after_gc,
1644 minimum_desired_capacity, (double) MinHeapFreeRatio);
1645 expand(expand_bytes);
1646
1647 // No expansion, now see if we want to shrink
1648 } else if (capacity_after_gc > maximum_desired_capacity) {
1649 // Capacity too large, compute shrinking size
1650 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1651 ergo_verbose4(ErgoHeapSizing,
1652 "attempt heap shrinking",
1653 ergo_format_reason("capacity higher than "
1654 "max desired capacity after Full GC")
1655 ergo_format_byte("capacity")
1656 ergo_format_byte("occupancy")
1657 ergo_format_byte_perc("max desired capacity"),
1658 capacity_after_gc, used_after_gc,
1659 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1660 shrink(shrink_bytes);
1661 }
1662 }
1663
1664
1665 HeapWord*
1666 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1667 bool* succeeded) {
1668 assert_at_safepoint(true /* should_be_vm_thread */);
1669
1670 *succeeded = true;
1671 // Let's attempt the allocation first.
1672 HeapWord* result =
1673 attempt_allocation_at_safepoint(word_size,
1674 false /* expect_null_mutator_alloc_region */);
1675 if (result != NULL) {
1676 assert(*succeeded, "sanity");
1677 return result;
1678 }
1679
1680 // In a G1 heap, we're supposed to keep allocation from failing by
1681 // incremental pauses. Therefore, at least for now, we'll favor
1682 // expansion over collection. (This might change in the future if we can
1683 // do something smarter than full collection to satisfy a failed alloc.)
1684 result = expand_and_allocate(word_size);
1685 if (result != NULL) {
1686 assert(*succeeded, "sanity");
1687 return result;
1688 }
1689
1690 // Expansion didn't work, we'll try to do a Full GC.
1691 bool gc_succeeded = do_collection(false, /* explicit_gc */
1692 false, /* clear_all_soft_refs */
1693 word_size);
1694 if (!gc_succeeded) {
1695 *succeeded = false;
1696 return NULL;
1697 }
1698
1699 // Retry the allocation
1700 result = attempt_allocation_at_safepoint(word_size,
1701 true /* expect_null_mutator_alloc_region */);
1702 if (result != NULL) {
1703 assert(*succeeded, "sanity");
1704 return result;
1705 }
1706
1707 // Then, try a Full GC that will collect all soft references.
1708 gc_succeeded = do_collection(false, /* explicit_gc */
1709 true, /* clear_all_soft_refs */
1710 word_size);
1711 if (!gc_succeeded) {
1712 *succeeded = false;
1713 return NULL;
1714 }
1715
1716 // Retry the allocation once more
1717 result = attempt_allocation_at_safepoint(word_size,
1718 true /* expect_null_mutator_alloc_region */);
1719 if (result != NULL) {
1720 assert(*succeeded, "sanity");
1721 return result;
1722 }
1723
1724 assert(!collector_policy()->should_clear_all_soft_refs(),
1725 "Flag should have been handled and cleared prior to this point");
1726
1727 // What else? We might try synchronous finalization later. If the total
1728 // space available is large enough for the allocation, then a more
1729 // complete compaction phase than we've tried so far might be
1730 // appropriate.
1731 assert(*succeeded, "sanity");
1732 return NULL;
1733 }
1734
1735 // Attempting to expand the heap sufficiently
1736 // to support an allocation of the given "word_size". If
1737 // successful, perform the allocation and return the address of the
1738 // allocated block, or else "NULL".
1739
1740 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1741 assert_at_safepoint(true /* should_be_vm_thread */);
1742
1743 verify_region_sets_optional();
1744
1745 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1746 ergo_verbose1(ErgoHeapSizing,
1747 "attempt heap expansion",
1748 ergo_format_reason("allocation request failed")
1749 ergo_format_byte("allocation request"),
1750 word_size * HeapWordSize);
1751 if (expand(expand_bytes)) {
1752 _hrs.verify_optional();
1753 verify_region_sets_optional();
1754 return attempt_allocation_at_safepoint(word_size,
1755 false /* expect_null_mutator_alloc_region */);
1756 }
1757 return NULL;
1758 }
1759
1760 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1761 HeapWord* new_end) {
1762 assert(old_end != new_end, "don't call this otherwise");
1763 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1764
1765 // Update the committed mem region.
1766 _g1_committed.set_end(new_end);
1767 // Tell the card table about the update.
1768 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1769 // Tell the BOT about the update.
1770 _bot_shared->resize(_g1_committed.word_size());
1771 // Tell the hot card cache about the update
1772 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1773 }
1774
1775 bool G1CollectedHeap::expand(size_t expand_bytes) {
1776 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1777 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1778 HeapRegion::GrainBytes);
1779 ergo_verbose2(ErgoHeapSizing,
1780 "expand the heap",
1781 ergo_format_byte("requested expansion amount")
1782 ergo_format_byte("attempted expansion amount"),
1783 expand_bytes, aligned_expand_bytes);
1784
1785 if (_g1_storage.uncommitted_size() == 0) {
1786 ergo_verbose0(ErgoHeapSizing,
1787 "did not expand the heap",
1788 ergo_format_reason("heap already fully expanded"));
1789 return false;
1790 }
1791
1792 // First commit the memory.
1793 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1794 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1795 if (successful) {
1796 // Then propagate this update to the necessary data structures.
1797 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1798 update_committed_space(old_end, new_end);
1799
1800 FreeRegionList expansion_list("Local Expansion List");
1801 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1802 assert(mr.start() == old_end, "post-condition");
1803 // mr might be a smaller region than what was requested if
1804 // expand_by() was unable to allocate the HeapRegion instances
1805 assert(mr.end() <= new_end, "post-condition");
1806
1807 size_t actual_expand_bytes = mr.byte_size();
1808 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1809 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1810 "post-condition");
1811 if (actual_expand_bytes < aligned_expand_bytes) {
1812 // We could not expand _hrs to the desired size. In this case we
1813 // need to shrink the committed space accordingly.
1814 assert(mr.end() < new_end, "invariant");
1815
1816 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1817 // First uncommit the memory.
1818 _g1_storage.shrink_by(diff_bytes);
1819 // Then propagate this update to the necessary data structures.
1820 update_committed_space(new_end, mr.end());
1821 }
1822 _free_list.add_as_tail(&expansion_list);
1823
1824 if (_hr_printer.is_active()) {
1825 HeapWord* curr = mr.start();
1826 while (curr < mr.end()) {
1827 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1828 _hr_printer.commit(curr, curr_end);
1829 curr = curr_end;
1830 }
1831 assert(curr == mr.end(), "post-condition");
1832 }
1833 g1_policy()->record_new_heap_size(n_regions());
1834 } else {
1835 ergo_verbose0(ErgoHeapSizing,
1836 "did not expand the heap",
1837 ergo_format_reason("heap expansion operation failed"));
1838 // The expansion of the virtual storage space was unsuccessful.
1839 // Let's see if it was because we ran out of swap.
1840 if (G1ExitOnExpansionFailure &&
1841 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1842 // We had head room...
1843 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1844 }
1845 }
1846 return successful;
1847 }
1848
1849 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1850 size_t aligned_shrink_bytes =
1851 ReservedSpace::page_align_size_down(shrink_bytes);
1852 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1853 HeapRegion::GrainBytes);
1854 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1855
1856 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1857 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1858 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1859
1860 ergo_verbose3(ErgoHeapSizing,
1861 "shrink the heap",
1862 ergo_format_byte("requested shrinking amount")
1863 ergo_format_byte("aligned shrinking amount")
1864 ergo_format_byte("attempted shrinking amount"),
1865 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1866 if (num_regions_removed > 0) {
1867 _g1_storage.shrink_by(shrunk_bytes);
1868 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1869
1870 if (_hr_printer.is_active()) {
1871 HeapWord* curr = old_end;
1872 while (curr > new_end) {
1873 HeapWord* curr_end = curr;
1874 curr -= HeapRegion::GrainWords;
1875 _hr_printer.uncommit(curr, curr_end);
1876 }
1877 }
1878
1879 _expansion_regions += num_regions_removed;
1880 update_committed_space(old_end, new_end);
1881 HeapRegionRemSet::shrink_heap(n_regions());
1882 g1_policy()->record_new_heap_size(n_regions());
1883 } else {
1884 ergo_verbose0(ErgoHeapSizing,
1885 "did not shrink the heap",
1886 ergo_format_reason("heap shrinking operation failed"));
1887 }
1888 }
1889
1890 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1891 verify_region_sets_optional();
1892
1893 // We should only reach here at the end of a Full GC which means we
1894 // should not not be holding to any GC alloc regions. The method
1895 // below will make sure of that and do any remaining clean up.
1896 abandon_gc_alloc_regions();
1897
1898 // Instead of tearing down / rebuilding the free lists here, we
1899 // could instead use the remove_all_pending() method on free_list to
1900 // remove only the ones that we need to remove.
1901 tear_down_region_sets(true /* free_list_only */);
1902 shrink_helper(shrink_bytes);
1903 rebuild_region_sets(true /* free_list_only */);
1904
1905 _hrs.verify_optional();
1906 verify_region_sets_optional();
1907 }
1908
1909 // Public methods.
1910
1911 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1912 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1913 #endif // _MSC_VER
1914
1915
1916 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1917 SharedHeap(policy_),
1918 _g1_policy(policy_),
1919 _dirty_card_queue_set(false),
1920 _into_cset_dirty_card_queue_set(false),
1921 _is_alive_closure_cm(this),
1922 _is_alive_closure_stw(this),
1923 _ref_processor_cm(NULL),
1924 _ref_processor_stw(NULL),
1925 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1926 _bot_shared(NULL),
1927 _evac_failure_scan_stack(NULL),
1928 _mark_in_progress(false),
1929 _cg1r(NULL), _summary_bytes_used(0),
1930 _g1mm(NULL),
1931 _refine_cte_cl(NULL),
1932 _full_collection(false),
1933 _free_list("Master Free List"),
1934 _secondary_free_list("Secondary Free List"),
1935 _old_set("Old Set"),
1936 _humongous_set("Master Humongous Set"),
1937 _free_regions_coming(false),
1938 _young_list(new YoungList(this)),
1939 _gc_time_stamp(0),
1940 _retained_old_gc_alloc_region(NULL),
1941 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1942 _old_plab_stats(OldPLABSize, PLABWeight),
1943 _expand_heap_after_alloc_failure(true),
1944 _surviving_young_words(NULL),
1945 _old_marking_cycles_started(0),
1946 _old_marking_cycles_completed(0),
1947 _concurrent_cycle_started(false),
1948 _in_cset_fast_test(NULL),
1949 _in_cset_fast_test_base(NULL),
1950 _dirty_cards_region_list(NULL),
1951 _worker_cset_start_region(NULL),
1952 _worker_cset_start_region_time_stamp(NULL),
1953 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1954 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1955 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1956 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1957
1958 _g1h = this;
1959 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1960 vm_exit_during_initialization("Failed necessary allocation.");
1961 }
1962
1963 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1964
1965 int n_queues = MAX2((int)ParallelGCThreads, 1);
1966 _task_queues = new RefToScanQueueSet(n_queues);
1967
1968 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1969 assert(n_rem_sets > 0, "Invariant.");
1970
1971 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1972 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1973 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1974
1975 for (int i = 0; i < n_queues; i++) {
1976 RefToScanQueue* q = new RefToScanQueue();
1977 q->initialize();
1978 _task_queues->register_queue(i, q);
1979 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1980 }
1981 clear_cset_start_regions();
1982
1983 // Initialize the G1EvacuationFailureALot counters and flags.
1984 NOT_PRODUCT(reset_evacuation_should_fail();)
1985
1986 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1987 }
1988
1989 jint G1CollectedHeap::initialize() {
1990 CollectedHeap::pre_initialize();
1991 os::enable_vtime();
1992
1993 G1Log::init();
1994
1995 // Necessary to satisfy locking discipline assertions.
1996
1997 MutexLocker x(Heap_lock);
1998
1999 // We have to initialize the printer before committing the heap, as
2000 // it will be used then.
2001 _hr_printer.set_active(G1PrintHeapRegions);
2002
2003 // While there are no constraints in the GC code that HeapWordSize
2004 // be any particular value, there are multiple other areas in the
2005 // system which believe this to be true (e.g. oop->object_size in some
2006 // cases incorrectly returns the size in wordSize units rather than
2007 // HeapWordSize).
2008 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2009
2010 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2011 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2012 size_t heap_alignment = collector_policy()->heap_alignment();
2013
2014 // Ensure that the sizes are properly aligned.
2015 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2016 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2017 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2018
2019 _cg1r = new ConcurrentG1Refine(this);
2020
2021 // Reserve the maximum.
2022
2023 // When compressed oops are enabled, the preferred heap base
2024 // is calculated by subtracting the requested size from the
2025 // 32Gb boundary and using the result as the base address for
2026 // heap reservation. If the requested size is not aligned to
2027 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2028 // into the ReservedHeapSpace constructor) then the actual
2029 // base of the reserved heap may end up differing from the
2030 // address that was requested (i.e. the preferred heap base).
2031 // If this happens then we could end up using a non-optimal
2032 // compressed oops mode.
2033
2034 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2035 heap_alignment);
2036
2037 // It is important to do this in a way such that concurrent readers can't
2038 // temporarily think something is in the heap. (I've actually seen this
2039 // happen in asserts: DLD.)
2040 _reserved.set_word_size(0);
2041 _reserved.set_start((HeapWord*)heap_rs.base());
2042 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2043
2044 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2045
2046 // Create the gen rem set (and barrier set) for the entire reserved region.
2047 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2048 set_barrier_set(rem_set()->bs());
2049 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2050 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2051 return JNI_ENOMEM;
2052 }
2053
2054 // Also create a G1 rem set.
2055 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2056
2057 // Carve out the G1 part of the heap.
2058
2059 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2060 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2061 g1_rs.size()/HeapWordSize);
2062
2063 _g1_storage.initialize(g1_rs, 0);
2064 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2065 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2066 (HeapWord*) _g1_reserved.end());
2067 assert(_hrs.max_length() == _expansion_regions,
2068 err_msg("max length: %u expansion regions: %u",
2069 _hrs.max_length(), _expansion_regions));
2070
2071 // Do later initialization work for concurrent refinement.
2072 _cg1r->init();
2073
2074 // 6843694 - ensure that the maximum region index can fit
2075 // in the remembered set structures.
2076 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2077 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2078
2079 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2080 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2081 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2082 "too many cards per region");
2083
2084 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2085
2086 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2087 heap_word_size(init_byte_size));
2088
2089 _g1h = this;
2090
2091 _in_cset_fast_test_length = max_regions();
2092 _in_cset_fast_test_base =
2093 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2094
2095 // We're biasing _in_cset_fast_test to avoid subtracting the
2096 // beginning of the heap every time we want to index; basically
2097 // it's the same with what we do with the card table.
2098 _in_cset_fast_test = _in_cset_fast_test_base -
2099 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2100
2101 // Clear the _cset_fast_test bitmap in anticipation of adding
2102 // regions to the incremental collection set for the first
2103 // evacuation pause.
2104 clear_cset_fast_test();
2105
2106 // Create the ConcurrentMark data structure and thread.
2107 // (Must do this late, so that "max_regions" is defined.)
2108 _cm = new ConcurrentMark(this, heap_rs);
2109 if (_cm == NULL || !_cm->completed_initialization()) {
2110 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2111 return JNI_ENOMEM;
2112 }
2113 _cmThread = _cm->cmThread();
2114
2115 // Initialize the from_card cache structure of HeapRegionRemSet.
2116 HeapRegionRemSet::init_heap(max_regions());
2117
2118 // Now expand into the initial heap size.
2119 if (!expand(init_byte_size)) {
2120 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2121 return JNI_ENOMEM;
2122 }
2123
2124 // Perform any initialization actions delegated to the policy.
2125 g1_policy()->init();
2126
2127 _refine_cte_cl =
2128 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2129 g1_rem_set(),
2130 concurrent_g1_refine());
2131 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2132
2133 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2134 SATB_Q_FL_lock,
2135 G1SATBProcessCompletedThreshold,
2136 Shared_SATB_Q_lock);
2137
2138 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2139 DirtyCardQ_FL_lock,
2140 concurrent_g1_refine()->yellow_zone(),
2141 concurrent_g1_refine()->red_zone(),
2142 Shared_DirtyCardQ_lock);
2143
2144 if (G1DeferredRSUpdate) {
2145 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2146 DirtyCardQ_FL_lock,
2147 -1, // never trigger processing
2148 -1, // no limit on length
2149 Shared_DirtyCardQ_lock,
2150 &JavaThread::dirty_card_queue_set());
2151 }
2152
2153 // Initialize the card queue set used to hold cards containing
2154 // references into the collection set.
2155 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2156 DirtyCardQ_FL_lock,
2157 -1, // never trigger processing
2158 -1, // no limit on length
2159 Shared_DirtyCardQ_lock,
2160 &JavaThread::dirty_card_queue_set());
2161
2162 // In case we're keeping closure specialization stats, initialize those
2163 // counts and that mechanism.
2164 SpecializationStats::clear();
2165
2166 // Here we allocate the dummy full region that is required by the
2167 // G1AllocRegion class. If we don't pass an address in the reserved
2168 // space here, lots of asserts fire.
2169
2170 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2171 _g1_reserved.start());
2172 // We'll re-use the same region whether the alloc region will
2173 // require BOT updates or not and, if it doesn't, then a non-young
2174 // region will complain that it cannot support allocations without
2175 // BOT updates. So we'll tag the dummy region as young to avoid that.
2176 dummy_region->set_young();
2177 // Make sure it's full.
2178 dummy_region->set_top(dummy_region->end());
2179 G1AllocRegion::setup(this, dummy_region);
2180
2181 init_mutator_alloc_region();
2182
2183 // Do create of the monitoring and management support so that
2184 // values in the heap have been properly initialized.
2185 _g1mm = new G1MonitoringSupport(this);
2186
2187 return JNI_OK;
2188 }
2189
2190 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2191 return HeapRegion::max_region_size();
2192 }
2193
2194 void G1CollectedHeap::ref_processing_init() {
2195 // Reference processing in G1 currently works as follows:
2196 //
2197 // * There are two reference processor instances. One is
2198 // used to record and process discovered references
2199 // during concurrent marking; the other is used to
2200 // record and process references during STW pauses
2201 // (both full and incremental).
2202 // * Both ref processors need to 'span' the entire heap as
2203 // the regions in the collection set may be dotted around.
2204 //
2205 // * For the concurrent marking ref processor:
2206 // * Reference discovery is enabled at initial marking.
2207 // * Reference discovery is disabled and the discovered
2208 // references processed etc during remarking.
2209 // * Reference discovery is MT (see below).
2210 // * Reference discovery requires a barrier (see below).
2211 // * Reference processing may or may not be MT
2212 // (depending on the value of ParallelRefProcEnabled
2213 // and ParallelGCThreads).
2214 // * A full GC disables reference discovery by the CM
2215 // ref processor and abandons any entries on it's
2216 // discovered lists.
2217 //
2218 // * For the STW processor:
2219 // * Non MT discovery is enabled at the start of a full GC.
2220 // * Processing and enqueueing during a full GC is non-MT.
2221 // * During a full GC, references are processed after marking.
2222 //
2223 // * Discovery (may or may not be MT) is enabled at the start
2224 // of an incremental evacuation pause.
2225 // * References are processed near the end of a STW evacuation pause.
2226 // * For both types of GC:
2227 // * Discovery is atomic - i.e. not concurrent.
2228 // * Reference discovery will not need a barrier.
2229
2230 SharedHeap::ref_processing_init();
2231 MemRegion mr = reserved_region();
2232
2233 // Concurrent Mark ref processor
2234 _ref_processor_cm =
2235 new ReferenceProcessor(mr, // span
2236 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2237 // mt processing
2238 (int) ParallelGCThreads,
2239 // degree of mt processing
2240 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2241 // mt discovery
2242 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2243 // degree of mt discovery
2244 false,
2245 // Reference discovery is not atomic
2246 &_is_alive_closure_cm,
2247 // is alive closure
2248 // (for efficiency/performance)
2249 true);
2250 // Setting next fields of discovered
2251 // lists requires a barrier.
2252
2253 // STW ref processor
2254 _ref_processor_stw =
2255 new ReferenceProcessor(mr, // span
2256 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2257 // mt processing
2258 MAX2((int)ParallelGCThreads, 1),
2259 // degree of mt processing
2260 (ParallelGCThreads > 1),
2261 // mt discovery
2262 MAX2((int)ParallelGCThreads, 1),
2263 // degree of mt discovery
2264 true,
2265 // Reference discovery is atomic
2266 &_is_alive_closure_stw,
2267 // is alive closure
2268 // (for efficiency/performance)
2269 false);
2270 // Setting next fields of discovered
2271 // lists requires a barrier.
2272 }
2273
2274 size_t G1CollectedHeap::capacity() const {
2275 return _g1_committed.byte_size();
2276 }
2277
2278 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2279 assert(!hr->continuesHumongous(), "pre-condition");
2280 hr->reset_gc_time_stamp();
2281 if (hr->startsHumongous()) {
2282 uint first_index = hr->hrs_index() + 1;
2283 uint last_index = hr->last_hc_index();
2284 for (uint i = first_index; i < last_index; i += 1) {
2285 HeapRegion* chr = region_at(i);
2286 assert(chr->continuesHumongous(), "sanity");
2287 chr->reset_gc_time_stamp();
2288 }
2289 }
2290 }
2291
2292 #ifndef PRODUCT
2293 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2294 private:
2295 unsigned _gc_time_stamp;
2296 bool _failures;
2297
2298 public:
2299 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2300 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2301
2302 virtual bool doHeapRegion(HeapRegion* hr) {
2303 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2304 if (_gc_time_stamp != region_gc_time_stamp) {
2305 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2306 "expected %d", HR_FORMAT_PARAMS(hr),
2307 region_gc_time_stamp, _gc_time_stamp);
2308 _failures = true;
2309 }
2310 return false;
2311 }
2312
2313 bool failures() { return _failures; }
2314 };
2315
2316 void G1CollectedHeap::check_gc_time_stamps() {
2317 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2318 heap_region_iterate(&cl);
2319 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2320 }
2321 #endif // PRODUCT
2322
2323 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2324 DirtyCardQueue* into_cset_dcq,
2325 bool concurrent,
2326 int worker_i) {
2327 // Clean cards in the hot card cache
2328 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2329 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2330
2331 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2332 int n_completed_buffers = 0;
2333 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2334 n_completed_buffers++;
2335 }
2336 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2337 dcqs.clear_n_completed_buffers();
2338 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2339 }
2340
2341
2342 // Computes the sum of the storage used by the various regions.
2343
2344 size_t G1CollectedHeap::used() const {
2345 assert(Heap_lock->owner() != NULL,
2346 "Should be owned on this thread's behalf.");
2347 size_t result = _summary_bytes_used;
2348 // Read only once in case it is set to NULL concurrently
2349 HeapRegion* hr = _mutator_alloc_region.get();
2350 if (hr != NULL)
2351 result += hr->used();
2352 return result;
2353 }
2354
2355 size_t G1CollectedHeap::used_unlocked() const {
2356 size_t result = _summary_bytes_used;
2357 return result;
2358 }
2359
2360 class SumUsedClosure: public HeapRegionClosure {
2361 size_t _used;
2362 public:
2363 SumUsedClosure() : _used(0) {}
2364 bool doHeapRegion(HeapRegion* r) {
2365 if (!r->continuesHumongous()) {
2366 _used += r->used();
2367 }
2368 return false;
2369 }
2370 size_t result() { return _used; }
2371 };
2372
2373 size_t G1CollectedHeap::recalculate_used() const {
2374 SumUsedClosure blk;
2375 heap_region_iterate(&blk);
2376 return blk.result();
2377 }
2378
2379 size_t G1CollectedHeap::unsafe_max_alloc() {
2380 if (free_regions() > 0) return HeapRegion::GrainBytes;
2381 // otherwise, is there space in the current allocation region?
2382
2383 // We need to store the current allocation region in a local variable
2384 // here. The problem is that this method doesn't take any locks and
2385 // there may be other threads which overwrite the current allocation
2386 // region field. attempt_allocation(), for example, sets it to NULL
2387 // and this can happen *after* the NULL check here but before the call
2388 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2389 // to be a problem in the optimized build, since the two loads of the
2390 // current allocation region field are optimized away.
2391 HeapRegion* hr = _mutator_alloc_region.get();
2392 if (hr == NULL) {
2393 return 0;
2394 }
2395 return hr->free();
2396 }
2397
2398 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2399 switch (cause) {
2400 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2401 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2402 case GCCause::_g1_humongous_allocation: return true;
2403 default: return false;
2404 }
2405 }
2406
2407 #ifndef PRODUCT
2408 void G1CollectedHeap::allocate_dummy_regions() {
2409 // Let's fill up most of the region
2410 size_t word_size = HeapRegion::GrainWords - 1024;
2411 // And as a result the region we'll allocate will be humongous.
2412 guarantee(isHumongous(word_size), "sanity");
2413
2414 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2415 // Let's use the existing mechanism for the allocation
2416 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2417 if (dummy_obj != NULL) {
2418 MemRegion mr(dummy_obj, word_size);
2419 CollectedHeap::fill_with_object(mr);
2420 } else {
2421 // If we can't allocate once, we probably cannot allocate
2422 // again. Let's get out of the loop.
2423 break;
2424 }
2425 }
2426 }
2427 #endif // !PRODUCT
2428
2429 void G1CollectedHeap::increment_old_marking_cycles_started() {
2430 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2431 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2432 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2433 _old_marking_cycles_started, _old_marking_cycles_completed));
2434
2435 _old_marking_cycles_started++;
2436 }
2437
2438 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2439 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2440
2441 // We assume that if concurrent == true, then the caller is a
2442 // concurrent thread that was joined the Suspendible Thread
2443 // Set. If there's ever a cheap way to check this, we should add an
2444 // assert here.
2445
2446 // Given that this method is called at the end of a Full GC or of a
2447 // concurrent cycle, and those can be nested (i.e., a Full GC can
2448 // interrupt a concurrent cycle), the number of full collections
2449 // completed should be either one (in the case where there was no
2450 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2451 // behind the number of full collections started.
2452
2453 // This is the case for the inner caller, i.e. a Full GC.
2454 assert(concurrent ||
2455 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2456 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2457 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2458 "is inconsistent with _old_marking_cycles_completed = %u",
2459 _old_marking_cycles_started, _old_marking_cycles_completed));
2460
2461 // This is the case for the outer caller, i.e. the concurrent cycle.
2462 assert(!concurrent ||
2463 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2464 err_msg("for outer caller (concurrent cycle): "
2465 "_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 _old_marking_cycles_completed += 1;
2470
2471 // We need to clear the "in_progress" flag in the CM thread before
2472 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2473 // is set) so that if a waiter requests another System.gc() it doesn't
2474 // incorrectly see that a marking cycle is still in progress.
2475 if (concurrent) {
2476 _cmThread->clear_in_progress();
2477 }
2478
2479 // This notify_all() will ensure that a thread that called
2480 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2481 // and it's waiting for a full GC to finish will be woken up. It is
2482 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2483 FullGCCount_lock->notify_all();
2484 }
2485
2486 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2487 _concurrent_cycle_started = true;
2488 _gc_timer_cm->register_gc_start(start_time);
2489
2490 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2491 trace_heap_before_gc(_gc_tracer_cm);
2492 }
2493
2494 void G1CollectedHeap::register_concurrent_cycle_end() {
2495 if (_concurrent_cycle_started) {
2496 if (_cm->has_aborted()) {
2497 _gc_tracer_cm->report_concurrent_mode_failure();
2498 }
2499
2500 _gc_timer_cm->register_gc_end();
2501 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2502
2503 _concurrent_cycle_started = false;
2504 }
2505 }
2506
2507 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2508 if (_concurrent_cycle_started) {
2509 trace_heap_after_gc(_gc_tracer_cm);
2510 }
2511 }
2512
2513 G1YCType G1CollectedHeap::yc_type() {
2514 bool is_young = g1_policy()->gcs_are_young();
2515 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2516 bool is_during_mark = mark_in_progress();
2517
2518 if (is_initial_mark) {
2519 return InitialMark;
2520 } else if (is_during_mark) {
2521 return DuringMark;
2522 } else if (is_young) {
2523 return Normal;
2524 } else {
2525 return Mixed;
2526 }
2527 }
2528
2529 void G1CollectedHeap::collect(GCCause::Cause cause) {
2530 assert_heap_not_locked();
2531
2532 unsigned int gc_count_before;
2533 unsigned int old_marking_count_before;
2534 bool retry_gc;
2535
2536 do {
2537 retry_gc = false;
2538
2539 {
2540 MutexLocker ml(Heap_lock);
2541
2542 // Read the GC count while holding the Heap_lock
2543 gc_count_before = total_collections();
2544 old_marking_count_before = _old_marking_cycles_started;
2545 }
2546
2547 if (should_do_concurrent_full_gc(cause)) {
2548 // Schedule an initial-mark evacuation pause that will start a
2549 // concurrent cycle. We're setting word_size to 0 which means that
2550 // we are not requesting a post-GC allocation.
2551 VM_G1IncCollectionPause op(gc_count_before,
2552 0, /* word_size */
2553 true, /* should_initiate_conc_mark */
2554 g1_policy()->max_pause_time_ms(),
2555 cause);
2556
2557 VMThread::execute(&op);
2558 if (!op.pause_succeeded()) {
2559 if (old_marking_count_before == _old_marking_cycles_started) {
2560 retry_gc = op.should_retry_gc();
2561 } else {
2562 // A Full GC happened while we were trying to schedule the
2563 // initial-mark GC. No point in starting a new cycle given
2564 // that the whole heap was collected anyway.
2565 }
2566
2567 if (retry_gc) {
2568 if (GC_locker::is_active_and_needs_gc()) {
2569 GC_locker::stall_until_clear();
2570 }
2571 }
2572 }
2573 } else {
2574 if (cause == GCCause::_gc_locker
2575 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2576
2577 // Schedule a standard evacuation pause. We're setting word_size
2578 // to 0 which means that we are not requesting a post-GC allocation.
2579 VM_G1IncCollectionPause op(gc_count_before,
2580 0, /* word_size */
2581 false, /* should_initiate_conc_mark */
2582 g1_policy()->max_pause_time_ms(),
2583 cause);
2584 VMThread::execute(&op);
2585 } else {
2586 // Schedule a Full GC.
2587 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2588 VMThread::execute(&op);
2589 }
2590 }
2591 } while (retry_gc);
2592 }
2593
2594 bool G1CollectedHeap::is_in(const void* p) const {
2595 if (_g1_committed.contains(p)) {
2596 // Given that we know that p is in the committed space,
2597 // heap_region_containing_raw() should successfully
2598 // return the containing region.
2599 HeapRegion* hr = heap_region_containing_raw(p);
2600 return hr->is_in(p);
2601 } else {
2602 return false;
2603 }
2604 }
2605
2606 // Iteration functions.
2607
2608 // Iterates an OopClosure over all ref-containing fields of objects
2609 // within a HeapRegion.
2610
2611 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2612 MemRegion _mr;
2613 ExtendedOopClosure* _cl;
2614 public:
2615 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2616 : _mr(mr), _cl(cl) {}
2617 bool doHeapRegion(HeapRegion* r) {
2618 if (!r->continuesHumongous()) {
2619 r->oop_iterate(_cl);
2620 }
2621 return false;
2622 }
2623 };
2624
2625 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2626 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2627 heap_region_iterate(&blk);
2628 }
2629
2630 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2631 IterateOopClosureRegionClosure blk(mr, cl);
2632 heap_region_iterate(&blk);
2633 }
2634
2635 // Iterates an ObjectClosure over all objects within a HeapRegion.
2636
2637 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2638 ObjectClosure* _cl;
2639 public:
2640 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2641 bool doHeapRegion(HeapRegion* r) {
2642 if (! r->continuesHumongous()) {
2643 r->object_iterate(_cl);
2644 }
2645 return false;
2646 }
2647 };
2648
2649 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2650 IterateObjectClosureRegionClosure blk(cl);
2651 heap_region_iterate(&blk);
2652 }
2653
2654 // Calls a SpaceClosure on a HeapRegion.
2655
2656 class SpaceClosureRegionClosure: public HeapRegionClosure {
2657 SpaceClosure* _cl;
2658 public:
2659 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2660 bool doHeapRegion(HeapRegion* r) {
2661 _cl->do_space(r);
2662 return false;
2663 }
2664 };
2665
2666 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2667 SpaceClosureRegionClosure blk(cl);
2668 heap_region_iterate(&blk);
2669 }
2670
2671 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2672 _hrs.iterate(cl);
2673 }
2674
2675 void
2676 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2677 uint worker_id,
2678 uint no_of_par_workers,
2679 jint claim_value) {
2680 const uint regions = n_regions();
2681 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2682 no_of_par_workers :
2683 1);
2684 assert(UseDynamicNumberOfGCThreads ||
2685 no_of_par_workers == workers()->total_workers(),
2686 "Non dynamic should use fixed number of workers");
2687 // try to spread out the starting points of the workers
2688 const HeapRegion* start_hr =
2689 start_region_for_worker(worker_id, no_of_par_workers);
2690 const uint start_index = start_hr->hrs_index();
2691
2692 // each worker will actually look at all regions
2693 for (uint count = 0; count < regions; ++count) {
2694 const uint index = (start_index + count) % regions;
2695 assert(0 <= index && index < regions, "sanity");
2696 HeapRegion* r = region_at(index);
2697 // we'll ignore "continues humongous" regions (we'll process them
2698 // when we come across their corresponding "start humongous"
2699 // region) and regions already claimed
2700 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2701 continue;
2702 }
2703 // OK, try to claim it
2704 if (r->claimHeapRegion(claim_value)) {
2705 // success!
2706 assert(!r->continuesHumongous(), "sanity");
2707 if (r->startsHumongous()) {
2708 // If the region is "starts humongous" we'll iterate over its
2709 // "continues humongous" first; in fact we'll do them
2710 // first. The order is important. In on case, calling the
2711 // closure on the "starts humongous" region might de-allocate
2712 // and clear all its "continues humongous" regions and, as a
2713 // result, we might end up processing them twice. So, we'll do
2714 // them first (notice: most closures will ignore them anyway) and
2715 // then we'll do the "starts humongous" region.
2716 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2717 HeapRegion* chr = region_at(ch_index);
2718
2719 // if the region has already been claimed or it's not
2720 // "continues humongous" we're done
2721 if (chr->claim_value() == claim_value ||
2722 !chr->continuesHumongous()) {
2723 break;
2724 }
2725
2726 // No one should have claimed it directly. We can given
2727 // that we claimed its "starts humongous" region.
2728 assert(chr->claim_value() != claim_value, "sanity");
2729 assert(chr->humongous_start_region() == r, "sanity");
2730
2731 if (chr->claimHeapRegion(claim_value)) {
2732 // we should always be able to claim it; no one else should
2733 // be trying to claim this region
2734
2735 bool res2 = cl->doHeapRegion(chr);
2736 assert(!res2, "Should not abort");
2737
2738 // Right now, this holds (i.e., no closure that actually
2739 // does something with "continues humongous" regions
2740 // clears them). We might have to weaken it in the future,
2741 // but let's leave these two asserts here for extra safety.
2742 assert(chr->continuesHumongous(), "should still be the case");
2743 assert(chr->humongous_start_region() == r, "sanity");
2744 } else {
2745 guarantee(false, "we should not reach here");
2746 }
2747 }
2748 }
2749
2750 assert(!r->continuesHumongous(), "sanity");
2751 bool res = cl->doHeapRegion(r);
2752 assert(!res, "Should not abort");
2753 }
2754 }
2755 }
2756
2757 class ResetClaimValuesClosure: public HeapRegionClosure {
2758 public:
2759 bool doHeapRegion(HeapRegion* r) {
2760 r->set_claim_value(HeapRegion::InitialClaimValue);
2761 return false;
2762 }
2763 };
2764
2765 void G1CollectedHeap::reset_heap_region_claim_values() {
2766 ResetClaimValuesClosure blk;
2767 heap_region_iterate(&blk);
2768 }
2769
2770 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2771 ResetClaimValuesClosure blk;
2772 collection_set_iterate(&blk);
2773 }
2774
2775 #ifdef ASSERT
2776 // This checks whether all regions in the heap have the correct claim
2777 // value. I also piggy-backed on this a check to ensure that the
2778 // humongous_start_region() information on "continues humongous"
2779 // regions is correct.
2780
2781 class CheckClaimValuesClosure : public HeapRegionClosure {
2782 private:
2783 jint _claim_value;
2784 uint _failures;
2785 HeapRegion* _sh_region;
2786
2787 public:
2788 CheckClaimValuesClosure(jint claim_value) :
2789 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2790 bool doHeapRegion(HeapRegion* r) {
2791 if (r->claim_value() != _claim_value) {
2792 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2793 "claim value = %d, should be %d",
2794 HR_FORMAT_PARAMS(r),
2795 r->claim_value(), _claim_value);
2796 ++_failures;
2797 }
2798 if (!r->isHumongous()) {
2799 _sh_region = NULL;
2800 } else if (r->startsHumongous()) {
2801 _sh_region = r;
2802 } else if (r->continuesHumongous()) {
2803 if (r->humongous_start_region() != _sh_region) {
2804 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2805 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2806 HR_FORMAT_PARAMS(r),
2807 r->humongous_start_region(),
2808 _sh_region);
2809 ++_failures;
2810 }
2811 }
2812 return false;
2813 }
2814 uint failures() { return _failures; }
2815 };
2816
2817 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2818 CheckClaimValuesClosure cl(claim_value);
2819 heap_region_iterate(&cl);
2820 return cl.failures() == 0;
2821 }
2822
2823 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2824 private:
2825 jint _claim_value;
2826 uint _failures;
2827
2828 public:
2829 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2830 _claim_value(claim_value), _failures(0) { }
2831
2832 uint failures() { return _failures; }
2833
2834 bool doHeapRegion(HeapRegion* hr) {
2835 assert(hr->in_collection_set(), "how?");
2836 assert(!hr->isHumongous(), "H-region in CSet");
2837 if (hr->claim_value() != _claim_value) {
2838 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2839 "claim value = %d, should be %d",
2840 HR_FORMAT_PARAMS(hr),
2841 hr->claim_value(), _claim_value);
2842 _failures += 1;
2843 }
2844 return false;
2845 }
2846 };
2847
2848 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2849 CheckClaimValuesInCSetHRClosure cl(claim_value);
2850 collection_set_iterate(&cl);
2851 return cl.failures() == 0;
2852 }
2853 #endif // ASSERT
2854
2855 // Clear the cached CSet starting regions and (more importantly)
2856 // the time stamps. Called when we reset the GC time stamp.
2857 void G1CollectedHeap::clear_cset_start_regions() {
2858 assert(_worker_cset_start_region != NULL, "sanity");
2859 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2860
2861 int n_queues = MAX2((int)ParallelGCThreads, 1);
2862 for (int i = 0; i < n_queues; i++) {
2863 _worker_cset_start_region[i] = NULL;
2864 _worker_cset_start_region_time_stamp[i] = 0;
2865 }
2866 }
2867
2868 // Given the id of a worker, obtain or calculate a suitable
2869 // starting region for iterating over the current collection set.
2870 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2871 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2872
2873 HeapRegion* result = NULL;
2874 unsigned gc_time_stamp = get_gc_time_stamp();
2875
2876 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2877 // Cached starting region for current worker was set
2878 // during the current pause - so it's valid.
2879 // Note: the cached starting heap region may be NULL
2880 // (when the collection set is empty).
2881 result = _worker_cset_start_region[worker_i];
2882 assert(result == NULL || result->in_collection_set(), "sanity");
2883 return result;
2884 }
2885
2886 // The cached entry was not valid so let's calculate
2887 // a suitable starting heap region for this worker.
2888
2889 // We want the parallel threads to start their collection
2890 // set iteration at different collection set regions to
2891 // avoid contention.
2892 // If we have:
2893 // n collection set regions
2894 // p threads
2895 // Then thread t will start at region floor ((t * n) / p)
2896
2897 result = g1_policy()->collection_set();
2898 if (G1CollectedHeap::use_parallel_gc_threads()) {
2899 uint cs_size = g1_policy()->cset_region_length();
2900 uint active_workers = workers()->active_workers();
2901 assert(UseDynamicNumberOfGCThreads ||
2902 active_workers == workers()->total_workers(),
2903 "Unless dynamic should use total workers");
2904
2905 uint end_ind = (cs_size * worker_i) / active_workers;
2906 uint start_ind = 0;
2907
2908 if (worker_i > 0 &&
2909 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2910 // Previous workers starting region is valid
2911 // so let's iterate from there
2912 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2913 result = _worker_cset_start_region[worker_i - 1];
2914 }
2915
2916 for (uint i = start_ind; i < end_ind; i++) {
2917 result = result->next_in_collection_set();
2918 }
2919 }
2920
2921 // Note: the calculated starting heap region may be NULL
2922 // (when the collection set is empty).
2923 assert(result == NULL || result->in_collection_set(), "sanity");
2924 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2925 "should be updated only once per pause");
2926 _worker_cset_start_region[worker_i] = result;
2927 OrderAccess::storestore();
2928 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2929 return result;
2930 }
2931
2932 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2933 uint no_of_par_workers) {
2934 uint worker_num =
2935 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2936 assert(UseDynamicNumberOfGCThreads ||
2937 no_of_par_workers == workers()->total_workers(),
2938 "Non dynamic should use fixed number of workers");
2939 const uint start_index = n_regions() * worker_i / worker_num;
2940 return region_at(start_index);
2941 }
2942
2943 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2944 HeapRegion* r = g1_policy()->collection_set();
2945 while (r != NULL) {
2946 HeapRegion* next = r->next_in_collection_set();
2947 if (cl->doHeapRegion(r)) {
2948 cl->incomplete();
2949 return;
2950 }
2951 r = next;
2952 }
2953 }
2954
2955 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2956 HeapRegionClosure *cl) {
2957 if (r == NULL) {
2958 // The CSet is empty so there's nothing to do.
2959 return;
2960 }
2961
2962 assert(r->in_collection_set(),
2963 "Start region must be a member of the collection set.");
2964 HeapRegion* cur = r;
2965 while (cur != NULL) {
2966 HeapRegion* next = cur->next_in_collection_set();
2967 if (cl->doHeapRegion(cur) && false) {
2968 cl->incomplete();
2969 return;
2970 }
2971 cur = next;
2972 }
2973 cur = g1_policy()->collection_set();
2974 while (cur != r) {
2975 HeapRegion* next = cur->next_in_collection_set();
2976 if (cl->doHeapRegion(cur) && false) {
2977 cl->incomplete();
2978 return;
2979 }
2980 cur = next;
2981 }
2982 }
2983
2984 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2985 return n_regions() > 0 ? region_at(0) : NULL;
2986 }
2987
2988
2989 Space* G1CollectedHeap::space_containing(const void* addr) const {
2990 Space* res = heap_region_containing(addr);
2991 return res;
2992 }
2993
2994 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2995 Space* sp = space_containing(addr);
2996 if (sp != NULL) {
2997 return sp->block_start(addr);
2998 }
2999 return NULL;
3000 }
3001
3002 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
3003 Space* sp = space_containing(addr);
3004 assert(sp != NULL, "block_size of address outside of heap");
3005 return sp->block_size(addr);
3006 }
3007
3008 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
3009 Space* sp = space_containing(addr);
3010 return sp->block_is_obj(addr);
3011 }
3012
3013 bool G1CollectedHeap::supports_tlab_allocation() const {
3014 return true;
3015 }
3016
3017 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
3018 return HeapRegion::GrainBytes;
3019 }
3020
3021 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3022 // Return the remaining space in the cur alloc region, but not less than
3023 // the min TLAB size.
3024
3025 // Also, this value can be at most the humongous object threshold,
3026 // since we can't allow tlabs to grow big enough to accommodate
3027 // humongous objects.
3028
3029 HeapRegion* hr = _mutator_alloc_region.get();
3030 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
3031 if (hr == NULL) {
3032 return max_tlab_size;
3033 } else {
3034 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
3035 }
3036 }
3037
3038 size_t G1CollectedHeap::max_capacity() const {
3039 return _g1_reserved.byte_size();
3040 }
3041
3042 jlong G1CollectedHeap::millis_since_last_gc() {
3043 // assert(false, "NYI");
3044 return 0;
3045 }
3046
3047 void G1CollectedHeap::prepare_for_verify() {
3048 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3049 ensure_parsability(false);
3050 }
3051 g1_rem_set()->prepare_for_verify();
3052 }
3053
3054 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3055 VerifyOption vo) {
3056 switch (vo) {
3057 case VerifyOption_G1UsePrevMarking:
3058 return hr->obj_allocated_since_prev_marking(obj);
3059 case VerifyOption_G1UseNextMarking:
3060 return hr->obj_allocated_since_next_marking(obj);
3061 case VerifyOption_G1UseMarkWord:
3062 return false;
3063 default:
3064 ShouldNotReachHere();
3065 }
3066 return false; // keep some compilers happy
3067 }
3068
3069 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3070 switch (vo) {
3071 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3072 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3073 case VerifyOption_G1UseMarkWord: return NULL;
3074 default: ShouldNotReachHere();
3075 }
3076 return NULL; // keep some compilers happy
3077 }
3078
3079 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3080 switch (vo) {
3081 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3082 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3083 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3084 default: ShouldNotReachHere();
3085 }
3086 return false; // keep some compilers happy
3087 }
3088
3089 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3090 switch (vo) {
3091 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3092 case VerifyOption_G1UseNextMarking: return "NTAMS";
3093 case VerifyOption_G1UseMarkWord: return "NONE";
3094 default: ShouldNotReachHere();
3095 }
3096 return NULL; // keep some compilers happy
3097 }
3098
3099 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3100 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3101 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3102 // we can change this closure to extend the simpler OopClosure.
3103 class VerifyRootsClosure: public OopsInGenClosure {
3104 private:
3105 G1CollectedHeap* _g1h;
3106 VerifyOption _vo;
3107 bool _failures;
3108 public:
3109 // _vo == UsePrevMarking -> use "prev" marking information,
3110 // _vo == UseNextMarking -> use "next" marking information,
3111 // _vo == UseMarkWord -> use mark word from object header.
3112 VerifyRootsClosure(VerifyOption vo) :
3113 _g1h(G1CollectedHeap::heap()),
3114 _vo(vo),
3115 _failures(false) { }
3116
3117 bool failures() { return _failures; }
3118
3119 template <class T> void do_oop_nv(T* p) {
3120 T heap_oop = oopDesc::load_heap_oop(p);
3121 if (!oopDesc::is_null(heap_oop)) {
3122 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3123 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3124 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3125 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3126 if (_vo == VerifyOption_G1UseMarkWord) {
3127 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3128 }
3129 obj->print_on(gclog_or_tty);
3130 _failures = true;
3131 }
3132 }
3133 }
3134
3135 void do_oop(oop* p) { do_oop_nv(p); }
3136 void do_oop(narrowOop* p) { do_oop_nv(p); }
3137 };
3138
3139 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3140 G1CollectedHeap* _g1h;
3141 OopClosure* _root_cl;
3142 nmethod* _nm;
3143 VerifyOption _vo;
3144 bool _failures;
3145
3146 template <class T> void do_oop_work(T* p) {
3147 // First verify that this root is live
3148 _root_cl->do_oop(p);
3149
3150 if (!G1VerifyHeapRegionCodeRoots) {
3151 // We're not verifying the code roots attached to heap region.
3152 return;
3153 }
3154
3155 // Don't check the code roots during marking verification in a full GC
3156 if (_vo == VerifyOption_G1UseMarkWord) {
3157 return;
3158 }
3159
3160 // Now verify that the current nmethod (which contains p) is
3161 // in the code root list of the heap region containing the
3162 // object referenced by p.
3163
3164 T heap_oop = oopDesc::load_heap_oop(p);
3165 if (!oopDesc::is_null(heap_oop)) {
3166 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3167
3168 // Now fetch the region containing the object
3169 HeapRegion* hr = _g1h->heap_region_containing(obj);
3170 HeapRegionRemSet* hrrs = hr->rem_set();
3171 // Verify that the strong code root list for this region
3172 // contains the nmethod
3173 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3174 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3175 "from nmethod "PTR_FORMAT" not in strong "
3176 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3177 p, _nm, hr->bottom(), hr->end());
3178 _failures = true;
3179 }
3180 }
3181 }
3182
3183 public:
3184 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3185 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3186
3187 void do_oop(oop* p) { do_oop_work(p); }
3188 void do_oop(narrowOop* p) { do_oop_work(p); }
3189
3190 void set_nmethod(nmethod* nm) { _nm = nm; }
3191 bool failures() { return _failures; }
3192 };
3193
3194 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3195 G1VerifyCodeRootOopClosure* _oop_cl;
3196
3197 public:
3198 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3199 _oop_cl(oop_cl) {}
3200
3201 void do_code_blob(CodeBlob* cb) {
3202 nmethod* nm = cb->as_nmethod_or_null();
3203 if (nm != NULL) {
3204 _oop_cl->set_nmethod(nm);
3205 nm->oops_do(_oop_cl);
3206 }
3207 }
3208 };
3209
3210 class YoungRefCounterClosure : public OopClosure {
3211 G1CollectedHeap* _g1h;
3212 int _count;
3213 public:
3214 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3215 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3216 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3217
3218 int count() { return _count; }
3219 void reset_count() { _count = 0; };
3220 };
3221
3222 class VerifyKlassClosure: public KlassClosure {
3223 YoungRefCounterClosure _young_ref_counter_closure;
3224 OopClosure *_oop_closure;
3225 public:
3226 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3227 void do_klass(Klass* k) {
3228 k->oops_do(_oop_closure);
3229
3230 _young_ref_counter_closure.reset_count();
3231 k->oops_do(&_young_ref_counter_closure);
3232 if (_young_ref_counter_closure.count() > 0) {
3233 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3234 }
3235 }
3236 };
3237
3238 class VerifyLivenessOopClosure: public OopClosure {
3239 G1CollectedHeap* _g1h;
3240 VerifyOption _vo;
3241 public:
3242 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3243 _g1h(g1h), _vo(vo)
3244 { }
3245 void do_oop(narrowOop *p) { do_oop_work(p); }
3246 void do_oop( oop *p) { do_oop_work(p); }
3247
3248 template <class T> void do_oop_work(T *p) {
3249 oop obj = oopDesc::load_decode_heap_oop(p);
3250 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3251 "Dead object referenced by a not dead object");
3252 }
3253 };
3254
3255 class VerifyObjsInRegionClosure: public ObjectClosure {
3256 private:
3257 G1CollectedHeap* _g1h;
3258 size_t _live_bytes;
3259 HeapRegion *_hr;
3260 VerifyOption _vo;
3261 public:
3262 // _vo == UsePrevMarking -> use "prev" marking information,
3263 // _vo == UseNextMarking -> use "next" marking information,
3264 // _vo == UseMarkWord -> use mark word from object header.
3265 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3266 : _live_bytes(0), _hr(hr), _vo(vo) {
3267 _g1h = G1CollectedHeap::heap();
3268 }
3269 void do_object(oop o) {
3270 VerifyLivenessOopClosure isLive(_g1h, _vo);
3271 assert(o != NULL, "Huh?");
3272 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3273 // If the object is alive according to the mark word,
3274 // then verify that the marking information agrees.
3275 // Note we can't verify the contra-positive of the
3276 // above: if the object is dead (according to the mark
3277 // word), it may not be marked, or may have been marked
3278 // but has since became dead, or may have been allocated
3279 // since the last marking.
3280 if (_vo == VerifyOption_G1UseMarkWord) {
3281 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3282 }
3283
3284 o->oop_iterate_no_header(&isLive);
3285 if (!_hr->obj_allocated_since_prev_marking(o)) {
3286 size_t obj_size = o->size(); // Make sure we don't overflow
3287 _live_bytes += (obj_size * HeapWordSize);
3288 }
3289 }
3290 }
3291 size_t live_bytes() { return _live_bytes; }
3292 };
3293
3294 class PrintObjsInRegionClosure : public ObjectClosure {
3295 HeapRegion *_hr;
3296 G1CollectedHeap *_g1;
3297 public:
3298 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3299 _g1 = G1CollectedHeap::heap();
3300 };
3301
3302 void do_object(oop o) {
3303 if (o != NULL) {
3304 HeapWord *start = (HeapWord *) o;
3305 size_t word_sz = o->size();
3306 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3307 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3308 (void*) o, word_sz,
3309 _g1->isMarkedPrev(o),
3310 _g1->isMarkedNext(o),
3311 _hr->obj_allocated_since_prev_marking(o));
3312 HeapWord *end = start + word_sz;
3313 HeapWord *cur;
3314 int *val;
3315 for (cur = start; cur < end; cur++) {
3316 val = (int *) cur;
3317 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3318 }
3319 }
3320 }
3321 };
3322
3323 class VerifyRegionClosure: public HeapRegionClosure {
3324 private:
3325 bool _par;
3326 VerifyOption _vo;
3327 bool _failures;
3328 public:
3329 // _vo == UsePrevMarking -> use "prev" marking information,
3330 // _vo == UseNextMarking -> use "next" marking information,
3331 // _vo == UseMarkWord -> use mark word from object header.
3332 VerifyRegionClosure(bool par, VerifyOption vo)
3333 : _par(par),
3334 _vo(vo),
3335 _failures(false) {}
3336
3337 bool failures() {
3338 return _failures;
3339 }
3340
3341 bool doHeapRegion(HeapRegion* r) {
3342 if (!r->continuesHumongous()) {
3343 bool failures = false;
3344 r->verify(_vo, &failures);
3345 if (failures) {
3346 _failures = true;
3347 } else {
3348 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3349 r->object_iterate(¬_dead_yet_cl);
3350 if (_vo != VerifyOption_G1UseNextMarking) {
3351 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3352 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3353 "max_live_bytes "SIZE_FORMAT" "
3354 "< calculated "SIZE_FORMAT,
3355 r->bottom(), r->end(),
3356 r->max_live_bytes(),
3357 not_dead_yet_cl.live_bytes());
3358 _failures = true;
3359 }
3360 } else {
3361 // When vo == UseNextMarking we cannot currently do a sanity
3362 // check on the live bytes as the calculation has not been
3363 // finalized yet.
3364 }
3365 }
3366 }
3367 return false; // stop the region iteration if we hit a failure
3368 }
3369 };
3370
3371 // This is the task used for parallel verification of the heap regions
3372
3373 class G1ParVerifyTask: public AbstractGangTask {
3374 private:
3375 G1CollectedHeap* _g1h;
3376 VerifyOption _vo;
3377 bool _failures;
3378
3379 public:
3380 // _vo == UsePrevMarking -> use "prev" marking information,
3381 // _vo == UseNextMarking -> use "next" marking information,
3382 // _vo == UseMarkWord -> use mark word from object header.
3383 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3384 AbstractGangTask("Parallel verify task"),
3385 _g1h(g1h),
3386 _vo(vo),
3387 _failures(false) { }
3388
3389 bool failures() {
3390 return _failures;
3391 }
3392
3393 void work(uint worker_id) {
3394 HandleMark hm;
3395 VerifyRegionClosure blk(true, _vo);
3396 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3397 _g1h->workers()->active_workers(),
3398 HeapRegion::ParVerifyClaimValue);
3399 if (blk.failures()) {
3400 _failures = true;
3401 }
3402 }
3403 };
3404
3405 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3406 if (SafepointSynchronize::is_at_safepoint()) {
3407 assert(Thread::current()->is_VM_thread(),
3408 "Expected to be executed serially by the VM thread at this point");
3409
3410 if (!silent) { gclog_or_tty->print("Roots "); }
3411 VerifyRootsClosure rootsCl(vo);
3412 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3413 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3414 VerifyKlassClosure klassCl(this, &rootsCl);
3415
3416 // We apply the relevant closures to all the oops in the
3417 // system dictionary, the string table and the code cache.
3418 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3419
3420 // Need cleared claim bits for the strong roots processing
3421 ClassLoaderDataGraph::clear_claimed_marks();
3422
3423 process_strong_roots(true, // activate StrongRootsScope
3424 false, // we set "is scavenging" to false,
3425 // so we don't reset the dirty cards.
3426 ScanningOption(so), // roots scanning options
3427 &rootsCl,
3428 &blobsCl,
3429 &klassCl
3430 );
3431
3432 bool failures = rootsCl.failures() || codeRootsCl.failures();
3433
3434 if (vo != VerifyOption_G1UseMarkWord) {
3435 // If we're verifying during a full GC then the region sets
3436 // will have been torn down at the start of the GC. Therefore
3437 // verifying the region sets will fail. So we only verify
3438 // the region sets when not in a full GC.
3439 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3440 verify_region_sets();
3441 }
3442
3443 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3444 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3445 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3446 "sanity check");
3447
3448 G1ParVerifyTask task(this, vo);
3449 assert(UseDynamicNumberOfGCThreads ||
3450 workers()->active_workers() == workers()->total_workers(),
3451 "If not dynamic should be using all the workers");
3452 int n_workers = workers()->active_workers();
3453 set_par_threads(n_workers);
3454 workers()->run_task(&task);
3455 set_par_threads(0);
3456 if (task.failures()) {
3457 failures = true;
3458 }
3459
3460 // Checks that the expected amount of parallel work was done.
3461 // The implication is that n_workers is > 0.
3462 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3463 "sanity check");
3464
3465 reset_heap_region_claim_values();
3466
3467 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3468 "sanity check");
3469 } else {
3470 VerifyRegionClosure blk(false, vo);
3471 heap_region_iterate(&blk);
3472 if (blk.failures()) {
3473 failures = true;
3474 }
3475 }
3476 if (!silent) gclog_or_tty->print("RemSet ");
3477 rem_set()->verify();
3478
3479 if (failures) {
3480 gclog_or_tty->print_cr("Heap:");
3481 // It helps to have the per-region information in the output to
3482 // help us track down what went wrong. This is why we call
3483 // print_extended_on() instead of print_on().
3484 print_extended_on(gclog_or_tty);
3485 gclog_or_tty->print_cr("");
3486 #ifndef PRODUCT
3487 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3488 concurrent_mark()->print_reachable("at-verification-failure",
3489 vo, false /* all */);
3490 }
3491 #endif
3492 gclog_or_tty->flush();
3493 }
3494 guarantee(!failures, "there should not have been any failures");
3495 } else {
3496 if (!silent)
3497 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3498 }
3499 }
3500
3501 void G1CollectedHeap::verify(bool silent) {
3502 verify(silent, VerifyOption_G1UsePrevMarking);
3503 }
3504
3505 double G1CollectedHeap::verify(bool guard, const char* msg) {
3506 double verify_time_ms = 0.0;
3507
3508 if (guard && total_collections() >= VerifyGCStartAt) {
3509 double verify_start = os::elapsedTime();
3510 HandleMark hm; // Discard invalid handles created during verification
3511 prepare_for_verify();
3512 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3513 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3514 }
3515
3516 return verify_time_ms;
3517 }
3518
3519 void G1CollectedHeap::verify_before_gc() {
3520 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3521 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3522 }
3523
3524 void G1CollectedHeap::verify_after_gc() {
3525 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3526 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3527 }
3528
3529 class PrintRegionClosure: public HeapRegionClosure {
3530 outputStream* _st;
3531 public:
3532 PrintRegionClosure(outputStream* st) : _st(st) {}
3533 bool doHeapRegion(HeapRegion* r) {
3534 r->print_on(_st);
3535 return false;
3536 }
3537 };
3538
3539 void G1CollectedHeap::print_on(outputStream* st) const {
3540 st->print(" %-20s", "garbage-first heap");
3541 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3542 capacity()/K, used_unlocked()/K);
3543 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3544 _g1_storage.low_boundary(),
3545 _g1_storage.high(),
3546 _g1_storage.high_boundary());
3547 st->cr();
3548 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3549 uint young_regions = _young_list->length();
3550 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3551 (size_t) young_regions * HeapRegion::GrainBytes / K);
3552 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3553 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3554 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3555 st->cr();
3556 MetaspaceAux::print_on(st);
3557 }
3558
3559 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3560 print_on(st);
3561
3562 // Print the per-region information.
3563 st->cr();
3564 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3565 "HS=humongous(starts), HC=humongous(continues), "
3566 "CS=collection set, F=free, TS=gc time stamp, "
3567 "PTAMS=previous top-at-mark-start, "
3568 "NTAMS=next top-at-mark-start)");
3569 PrintRegionClosure blk(st);
3570 heap_region_iterate(&blk);
3571 }
3572
3573 void G1CollectedHeap::print_on_error(outputStream* st) const {
3574 this->CollectedHeap::print_on_error(st);
3575
3576 if (_cm != NULL) {
3577 st->cr();
3578 _cm->print_on_error(st);
3579 }
3580 }
3581
3582 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3583 if (G1CollectedHeap::use_parallel_gc_threads()) {
3584 workers()->print_worker_threads_on(st);
3585 }
3586 _cmThread->print_on(st);
3587 st->cr();
3588 _cm->print_worker_threads_on(st);
3589 _cg1r->print_worker_threads_on(st);
3590 }
3591
3592 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3593 if (G1CollectedHeap::use_parallel_gc_threads()) {
3594 workers()->threads_do(tc);
3595 }
3596 tc->do_thread(_cmThread);
3597 _cg1r->threads_do(tc);
3598 }
3599
3600 void G1CollectedHeap::print_tracing_info() const {
3601 // We'll overload this to mean "trace GC pause statistics."
3602 if (TraceGen0Time || TraceGen1Time) {
3603 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3604 // to that.
3605 g1_policy()->print_tracing_info();
3606 }
3607 if (G1SummarizeRSetStats) {
3608 g1_rem_set()->print_summary_info();
3609 }
3610 if (G1SummarizeConcMark) {
3611 concurrent_mark()->print_summary_info();
3612 }
3613 g1_policy()->print_yg_surv_rate_info();
3614 SpecializationStats::print();
3615 }
3616
3617 #ifndef PRODUCT
3618 // Helpful for debugging RSet issues.
3619
3620 class PrintRSetsClosure : public HeapRegionClosure {
3621 private:
3622 const char* _msg;
3623 size_t _occupied_sum;
3624
3625 public:
3626 bool doHeapRegion(HeapRegion* r) {
3627 HeapRegionRemSet* hrrs = r->rem_set();
3628 size_t occupied = hrrs->occupied();
3629 _occupied_sum += occupied;
3630
3631 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3632 HR_FORMAT_PARAMS(r));
3633 if (occupied == 0) {
3634 gclog_or_tty->print_cr(" RSet is empty");
3635 } else {
3636 hrrs->print();
3637 }
3638 gclog_or_tty->print_cr("----------");
3639 return false;
3640 }
3641
3642 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3643 gclog_or_tty->cr();
3644 gclog_or_tty->print_cr("========================================");
3645 gclog_or_tty->print_cr(msg);
3646 gclog_or_tty->cr();
3647 }
3648
3649 ~PrintRSetsClosure() {
3650 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3651 gclog_or_tty->print_cr("========================================");
3652 gclog_or_tty->cr();
3653 }
3654 };
3655
3656 void G1CollectedHeap::print_cset_rsets() {
3657 PrintRSetsClosure cl("Printing CSet RSets");
3658 collection_set_iterate(&cl);
3659 }
3660
3661 void G1CollectedHeap::print_all_rsets() {
3662 PrintRSetsClosure cl("Printing All RSets");;
3663 heap_region_iterate(&cl);
3664 }
3665 #endif // PRODUCT
3666
3667 G1CollectedHeap* G1CollectedHeap::heap() {
3668 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3669 "not a garbage-first heap");
3670 return _g1h;
3671 }
3672
3673 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3674 // always_do_update_barrier = false;
3675 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3676 // Fill TLAB's and such
3677 ensure_parsability(true);
3678
3679 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3680 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3681 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3682 }
3683 }
3684
3685 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3686
3687 if (G1SummarizeRSetStats &&
3688 (G1SummarizeRSetStatsPeriod > 0) &&
3689 // we are at the end of the GC. Total collections has already been increased.
3690 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3691 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3692 }
3693
3694 // FIXME: what is this about?
3695 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3696 // is set.
3697 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3698 "derived pointer present"));
3699 // always_do_update_barrier = true;
3700
3701 // We have just completed a GC. Update the soft reference
3702 // policy with the new heap occupancy
3703 Universe::update_heap_info_at_gc();
3704 }
3705
3706 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3707 unsigned int gc_count_before,
3708 bool* succeeded,
3709 GCCause::Cause gc_cause) {
3710 assert_heap_not_locked_and_not_at_safepoint();
3711 g1_policy()->record_stop_world_start();
3712 VM_G1IncCollectionPause op(gc_count_before,
3713 word_size,
3714 false, /* should_initiate_conc_mark */
3715 g1_policy()->max_pause_time_ms(),
3716 gc_cause);
3717 VMThread::execute(&op);
3718
3719 HeapWord* result = op.result();
3720 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3721 assert(result == NULL || ret_succeeded,
3722 "the result should be NULL if the VM did not succeed");
3723 *succeeded = ret_succeeded;
3724
3725 assert_heap_not_locked();
3726 return result;
3727 }
3728
3729 void
3730 G1CollectedHeap::doConcurrentMark() {
3731 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3732 if (!_cmThread->in_progress()) {
3733 _cmThread->set_started();
3734 CGC_lock->notify();
3735 }
3736 }
3737
3738 size_t G1CollectedHeap::pending_card_num() {
3739 size_t extra_cards = 0;
3740 JavaThread *curr = Threads::first();
3741 while (curr != NULL) {
3742 DirtyCardQueue& dcq = curr->dirty_card_queue();
3743 extra_cards += dcq.size();
3744 curr = curr->next();
3745 }
3746 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3747 size_t buffer_size = dcqs.buffer_size();
3748 size_t buffer_num = dcqs.completed_buffers_num();
3749
3750 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3751 // in bytes - not the number of 'entries'. We need to convert
3752 // into a number of cards.
3753 return (buffer_size * buffer_num + extra_cards) / oopSize;
3754 }
3755
3756 size_t G1CollectedHeap::cards_scanned() {
3757 return g1_rem_set()->cardsScanned();
3758 }
3759
3760 void
3761 G1CollectedHeap::setup_surviving_young_words() {
3762 assert(_surviving_young_words == NULL, "pre-condition");
3763 uint array_length = g1_policy()->young_cset_region_length();
3764 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3765 if (_surviving_young_words == NULL) {
3766 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3767 "Not enough space for young surv words summary.");
3768 }
3769 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3770 #ifdef ASSERT
3771 for (uint i = 0; i < array_length; ++i) {
3772 assert( _surviving_young_words[i] == 0, "memset above" );
3773 }
3774 #endif // !ASSERT
3775 }
3776
3777 void
3778 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3779 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3780 uint array_length = g1_policy()->young_cset_region_length();
3781 for (uint i = 0; i < array_length; ++i) {
3782 _surviving_young_words[i] += surv_young_words[i];
3783 }
3784 }
3785
3786 void
3787 G1CollectedHeap::cleanup_surviving_young_words() {
3788 guarantee( _surviving_young_words != NULL, "pre-condition" );
3789 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3790 _surviving_young_words = NULL;
3791 }
3792
3793 #ifdef ASSERT
3794 class VerifyCSetClosure: public HeapRegionClosure {
3795 public:
3796 bool doHeapRegion(HeapRegion* hr) {
3797 // Here we check that the CSet region's RSet is ready for parallel
3798 // iteration. The fields that we'll verify are only manipulated
3799 // when the region is part of a CSet and is collected. Afterwards,
3800 // we reset these fields when we clear the region's RSet (when the
3801 // region is freed) so they are ready when the region is
3802 // re-allocated. The only exception to this is if there's an
3803 // evacuation failure and instead of freeing the region we leave
3804 // it in the heap. In that case, we reset these fields during
3805 // evacuation failure handling.
3806 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3807
3808 // Here's a good place to add any other checks we'd like to
3809 // perform on CSet regions.
3810 return false;
3811 }
3812 };
3813 #endif // ASSERT
3814
3815 #if TASKQUEUE_STATS
3816 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3817 st->print_raw_cr("GC Task Stats");
3818 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3819 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3820 }
3821
3822 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3823 print_taskqueue_stats_hdr(st);
3824
3825 TaskQueueStats totals;
3826 const int n = workers() != NULL ? workers()->total_workers() : 1;
3827 for (int i = 0; i < n; ++i) {
3828 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3829 totals += task_queue(i)->stats;
3830 }
3831 st->print_raw("tot "); totals.print(st); st->cr();
3832
3833 DEBUG_ONLY(totals.verify());
3834 }
3835
3836 void G1CollectedHeap::reset_taskqueue_stats() {
3837 const int n = workers() != NULL ? workers()->total_workers() : 1;
3838 for (int i = 0; i < n; ++i) {
3839 task_queue(i)->stats.reset();
3840 }
3841 }
3842 #endif // TASKQUEUE_STATS
3843
3844 void G1CollectedHeap::log_gc_header() {
3845 if (!G1Log::fine()) {
3846 return;
3847 }
3848
3849 gclog_or_tty->date_stamp(PrintGCDateStamps);
3850 gclog_or_tty->stamp(PrintGCTimeStamps);
3851
3852 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3853 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3854 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3855
3856 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3857 }
3858
3859 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3860 if (!G1Log::fine()) {
3861 return;
3862 }
3863
3864 if (G1Log::finer()) {
3865 if (evacuation_failed()) {
3866 gclog_or_tty->print(" (to-space exhausted)");
3867 }
3868 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3869 g1_policy()->phase_times()->note_gc_end();
3870 g1_policy()->phase_times()->print(pause_time_sec);
3871 g1_policy()->print_detailed_heap_transition();
3872 } else {
3873 if (evacuation_failed()) {
3874 gclog_or_tty->print("--");
3875 }
3876 g1_policy()->print_heap_transition();
3877 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3878 }
3879 gclog_or_tty->flush();
3880 }
3881
3882 bool
3883 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3884 assert_at_safepoint(true /* should_be_vm_thread */);
3885 guarantee(!is_gc_active(), "collection is not reentrant");
3886
3887 if (GC_locker::check_active_before_gc()) {
3888 return false;
3889 }
3890
3891 _gc_timer_stw->register_gc_start();
3892
3893 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3894
3895 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3896 ResourceMark rm;
3897
3898 print_heap_before_gc();
3899 trace_heap_before_gc(_gc_tracer_stw);
3900
3901 HRSPhaseSetter x(HRSPhaseEvacuation);
3902 verify_region_sets_optional();
3903 verify_dirty_young_regions();
3904
3905 // This call will decide whether this pause is an initial-mark
3906 // pause. If it is, during_initial_mark_pause() will return true
3907 // for the duration of this pause.
3908 g1_policy()->decide_on_conc_mark_initiation();
3909
3910 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3911 assert(!g1_policy()->during_initial_mark_pause() ||
3912 g1_policy()->gcs_are_young(), "sanity");
3913
3914 // We also do not allow mixed GCs during marking.
3915 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3916
3917 // Record whether this pause is an initial mark. When the current
3918 // thread has completed its logging output and it's safe to signal
3919 // the CM thread, the flag's value in the policy has been reset.
3920 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3921
3922 // Inner scope for scope based logging, timers, and stats collection
3923 {
3924 EvacuationInfo evacuation_info;
3925
3926 if (g1_policy()->during_initial_mark_pause()) {
3927 // We are about to start a marking cycle, so we increment the
3928 // full collection counter.
3929 increment_old_marking_cycles_started();
3930 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3931 }
3932
3933 _gc_tracer_stw->report_yc_type(yc_type());
3934
3935 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3936
3937 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3938 workers()->active_workers() : 1);
3939 double pause_start_sec = os::elapsedTime();
3940 g1_policy()->phase_times()->note_gc_start(active_workers);
3941 log_gc_header();
3942
3943 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3944 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3945
3946 // If the secondary_free_list is not empty, append it to the
3947 // free_list. No need to wait for the cleanup operation to finish;
3948 // the region allocation code will check the secondary_free_list
3949 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3950 // set, skip this step so that the region allocation code has to
3951 // get entries from the secondary_free_list.
3952 if (!G1StressConcRegionFreeing) {
3953 append_secondary_free_list_if_not_empty_with_lock();
3954 }
3955
3956 assert(check_young_list_well_formed(), "young list should be well formed");
3957 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3958 "sanity check");
3959
3960 // Don't dynamically change the number of GC threads this early. A value of
3961 // 0 is used to indicate serial work. When parallel work is done,
3962 // it will be set.
3963
3964 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3965 IsGCActiveMark x;
3966
3967 gc_prologue(false);
3968 increment_total_collections(false /* full gc */);
3969 increment_gc_time_stamp();
3970
3971 verify_before_gc();
3972
3973 COMPILER2_PRESENT(DerivedPointerTable::clear());
3974
3975 // Please see comment in g1CollectedHeap.hpp and
3976 // G1CollectedHeap::ref_processing_init() to see how
3977 // reference processing currently works in G1.
3978
3979 // Enable discovery in the STW reference processor
3980 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3981 true /*verify_no_refs*/);
3982
3983 {
3984 // We want to temporarily turn off discovery by the
3985 // CM ref processor, if necessary, and turn it back on
3986 // on again later if we do. Using a scoped
3987 // NoRefDiscovery object will do this.
3988 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3989
3990 // Forget the current alloc region (we might even choose it to be part
3991 // of the collection set!).
3992 release_mutator_alloc_region();
3993
3994 // We should call this after we retire the mutator alloc
3995 // region(s) so that all the ALLOC / RETIRE events are generated
3996 // before the start GC event.
3997 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3998
3999 // This timing is only used by the ergonomics to handle our pause target.
4000 // It is unclear why this should not include the full pause. We will
4001 // investigate this in CR 7178365.
4002 //
4003 // Preserving the old comment here if that helps the investigation:
4004 //
4005 // The elapsed time induced by the start time below deliberately elides
4006 // the possible verification above.
4007 double sample_start_time_sec = os::elapsedTime();
4008
4009 #if YOUNG_LIST_VERBOSE
4010 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4011 _young_list->print();
4012 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4013 #endif // YOUNG_LIST_VERBOSE
4014
4015 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4016
4017 double scan_wait_start = os::elapsedTime();
4018 // We have to wait until the CM threads finish scanning the
4019 // root regions as it's the only way to ensure that all the
4020 // objects on them have been correctly scanned before we start
4021 // moving them during the GC.
4022 bool waited = _cm->root_regions()->wait_until_scan_finished();
4023 double wait_time_ms = 0.0;
4024 if (waited) {
4025 double scan_wait_end = os::elapsedTime();
4026 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4027 }
4028 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4029
4030 #if YOUNG_LIST_VERBOSE
4031 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4032 _young_list->print();
4033 #endif // YOUNG_LIST_VERBOSE
4034
4035 if (g1_policy()->during_initial_mark_pause()) {
4036 concurrent_mark()->checkpointRootsInitialPre();
4037 }
4038
4039 #if YOUNG_LIST_VERBOSE
4040 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4041 _young_list->print();
4042 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4043 #endif // YOUNG_LIST_VERBOSE
4044
4045 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4046
4047 _cm->note_start_of_gc();
4048 // We should not verify the per-thread SATB buffers given that
4049 // we have not filtered them yet (we'll do so during the
4050 // GC). We also call this after finalize_cset() to
4051 // ensure that the CSet has been finalized.
4052 _cm->verify_no_cset_oops(true /* verify_stacks */,
4053 true /* verify_enqueued_buffers */,
4054 false /* verify_thread_buffers */,
4055 true /* verify_fingers */);
4056
4057 if (_hr_printer.is_active()) {
4058 HeapRegion* hr = g1_policy()->collection_set();
4059 while (hr != NULL) {
4060 G1HRPrinter::RegionType type;
4061 if (!hr->is_young()) {
4062 type = G1HRPrinter::Old;
4063 } else if (hr->is_survivor()) {
4064 type = G1HRPrinter::Survivor;
4065 } else {
4066 type = G1HRPrinter::Eden;
4067 }
4068 _hr_printer.cset(hr);
4069 hr = hr->next_in_collection_set();
4070 }
4071 }
4072
4073 #ifdef ASSERT
4074 VerifyCSetClosure cl;
4075 collection_set_iterate(&cl);
4076 #endif // ASSERT
4077
4078 setup_surviving_young_words();
4079
4080 // Initialize the GC alloc regions.
4081 init_gc_alloc_regions(evacuation_info);
4082
4083 // Actually do the work...
4084 evacuate_collection_set(evacuation_info);
4085
4086 // We do this to mainly verify the per-thread SATB buffers
4087 // (which have been filtered by now) since we didn't verify
4088 // them earlier. No point in re-checking the stacks / enqueued
4089 // buffers given that the CSet has not changed since last time
4090 // we checked.
4091 _cm->verify_no_cset_oops(false /* verify_stacks */,
4092 false /* verify_enqueued_buffers */,
4093 true /* verify_thread_buffers */,
4094 true /* verify_fingers */);
4095
4096 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4097 g1_policy()->clear_collection_set();
4098
4099 cleanup_surviving_young_words();
4100
4101 // Start a new incremental collection set for the next pause.
4102 g1_policy()->start_incremental_cset_building();
4103
4104 // Clear the _cset_fast_test bitmap in anticipation of adding
4105 // regions to the incremental collection set for the next
4106 // evacuation pause.
4107 clear_cset_fast_test();
4108
4109 _young_list->reset_sampled_info();
4110
4111 // Don't check the whole heap at this point as the
4112 // GC alloc regions from this pause have been tagged
4113 // as survivors and moved on to the survivor list.
4114 // Survivor regions will fail the !is_young() check.
4115 assert(check_young_list_empty(false /* check_heap */),
4116 "young list should be empty");
4117
4118 #if YOUNG_LIST_VERBOSE
4119 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4120 _young_list->print();
4121 #endif // YOUNG_LIST_VERBOSE
4122
4123 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4124 _young_list->first_survivor_region(),
4125 _young_list->last_survivor_region());
4126
4127 _young_list->reset_auxilary_lists();
4128
4129 if (evacuation_failed()) {
4130 _summary_bytes_used = recalculate_used();
4131 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4132 for (uint i = 0; i < n_queues; i++) {
4133 if (_evacuation_failed_info_array[i].has_failed()) {
4134 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4135 }
4136 }
4137 } else {
4138 // The "used" of the the collection set have already been subtracted
4139 // when they were freed. Add in the bytes evacuated.
4140 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4141 }
4142
4143 if (g1_policy()->during_initial_mark_pause()) {
4144 // We have to do this before we notify the CM threads that
4145 // they can start working to make sure that all the
4146 // appropriate initialization is done on the CM object.
4147 concurrent_mark()->checkpointRootsInitialPost();
4148 set_marking_started();
4149 // Note that we don't actually trigger the CM thread at
4150 // this point. We do that later when we're sure that
4151 // the current thread has completed its logging output.
4152 }
4153
4154 allocate_dummy_regions();
4155
4156 #if YOUNG_LIST_VERBOSE
4157 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4158 _young_list->print();
4159 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4160 #endif // YOUNG_LIST_VERBOSE
4161
4162 init_mutator_alloc_region();
4163
4164 {
4165 size_t expand_bytes = g1_policy()->expansion_amount();
4166 if (expand_bytes > 0) {
4167 size_t bytes_before = capacity();
4168 // No need for an ergo verbose message here,
4169 // expansion_amount() does this when it returns a value > 0.
4170 if (!expand(expand_bytes)) {
4171 // We failed to expand the heap so let's verify that
4172 // committed/uncommitted amount match the backing store
4173 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4174 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4175 }
4176 }
4177 }
4178
4179 // We redo the verification but now wrt to the new CSet which
4180 // has just got initialized after the previous CSet was freed.
4181 _cm->verify_no_cset_oops(true /* verify_stacks */,
4182 true /* verify_enqueued_buffers */,
4183 true /* verify_thread_buffers */,
4184 true /* verify_fingers */);
4185 _cm->note_end_of_gc();
4186
4187 // This timing is only used by the ergonomics to handle our pause target.
4188 // It is unclear why this should not include the full pause. We will
4189 // investigate this in CR 7178365.
4190 double sample_end_time_sec = os::elapsedTime();
4191 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4192 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4193
4194 MemoryService::track_memory_usage();
4195
4196 // In prepare_for_verify() below we'll need to scan the deferred
4197 // update buffers to bring the RSets up-to-date if
4198 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4199 // the update buffers we'll probably need to scan cards on the
4200 // regions we just allocated to (i.e., the GC alloc
4201 // regions). However, during the last GC we called
4202 // set_saved_mark() on all the GC alloc regions, so card
4203 // scanning might skip the [saved_mark_word()...top()] area of
4204 // those regions (i.e., the area we allocated objects into
4205 // during the last GC). But it shouldn't. Given that
4206 // saved_mark_word() is conditional on whether the GC time stamp
4207 // on the region is current or not, by incrementing the GC time
4208 // stamp here we invalidate all the GC time stamps on all the
4209 // regions and saved_mark_word() will simply return top() for
4210 // all the regions. This is a nicer way of ensuring this rather
4211 // than iterating over the regions and fixing them. In fact, the
4212 // GC time stamp increment here also ensures that
4213 // saved_mark_word() will return top() between pauses, i.e.,
4214 // during concurrent refinement. So we don't need the
4215 // is_gc_active() check to decided which top to use when
4216 // scanning cards (see CR 7039627).
4217 increment_gc_time_stamp();
4218
4219 verify_after_gc();
4220
4221 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4222 ref_processor_stw()->verify_no_references_recorded();
4223
4224 // CM reference discovery will be re-enabled if necessary.
4225 }
4226
4227 // We should do this after we potentially expand the heap so
4228 // that all the COMMIT events are generated before the end GC
4229 // event, and after we retire the GC alloc regions so that all
4230 // RETIRE events are generated before the end GC event.
4231 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4232
4233 if (mark_in_progress()) {
4234 concurrent_mark()->update_g1_committed();
4235 }
4236
4237 #ifdef TRACESPINNING
4238 ParallelTaskTerminator::print_termination_counts();
4239 #endif
4240
4241 gc_epilogue(false);
4242 }
4243
4244 // Print the remainder of the GC log output.
4245 log_gc_footer(os::elapsedTime() - pause_start_sec);
4246
4247 // It is not yet to safe to tell the concurrent mark to
4248 // start as we have some optional output below. We don't want the
4249 // output from the concurrent mark thread interfering with this
4250 // logging output either.
4251
4252 _hrs.verify_optional();
4253 verify_region_sets_optional();
4254
4255 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4256 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4257
4258 print_heap_after_gc();
4259 trace_heap_after_gc(_gc_tracer_stw);
4260
4261 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4262 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4263 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4264 // before any GC notifications are raised.
4265 g1mm()->update_sizes();
4266
4267 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4268 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4269 _gc_timer_stw->register_gc_end();
4270 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4271 }
4272 // It should now be safe to tell the concurrent mark thread to start
4273 // without its logging output interfering with the logging output
4274 // that came from the pause.
4275
4276 if (should_start_conc_mark) {
4277 // CAUTION: after the doConcurrentMark() call below,
4278 // the concurrent marking thread(s) could be running
4279 // concurrently with us. Make sure that anything after
4280 // this point does not assume that we are the only GC thread
4281 // running. Note: of course, the actual marking work will
4282 // not start until the safepoint itself is released in
4283 // ConcurrentGCThread::safepoint_desynchronize().
4284 doConcurrentMark();
4285 }
4286
4287 return true;
4288 }
4289
4290 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4291 {
4292 size_t gclab_word_size;
4293 switch (purpose) {
4294 case GCAllocForSurvived:
4295 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4296 break;
4297 case GCAllocForTenured:
4298 gclab_word_size = _old_plab_stats.desired_plab_sz();
4299 break;
4300 default:
4301 assert(false, "unknown GCAllocPurpose");
4302 gclab_word_size = _old_plab_stats.desired_plab_sz();
4303 break;
4304 }
4305
4306 // Prevent humongous PLAB sizes for two reasons:
4307 // * PLABs are allocated using a similar paths as oops, but should
4308 // never be in a humongous region
4309 // * Allowing humongous PLABs needlessly churns the region free lists
4310 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4311 }
4312
4313 void G1CollectedHeap::init_mutator_alloc_region() {
4314 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4315 _mutator_alloc_region.init();
4316 }
4317
4318 void G1CollectedHeap::release_mutator_alloc_region() {
4319 _mutator_alloc_region.release();
4320 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4321 }
4322
4323 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4324 assert_at_safepoint(true /* should_be_vm_thread */);
4325
4326 _survivor_gc_alloc_region.init();
4327 _old_gc_alloc_region.init();
4328 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4329 _retained_old_gc_alloc_region = NULL;
4330
4331 // We will discard the current GC alloc region if:
4332 // a) it's in the collection set (it can happen!),
4333 // b) it's already full (no point in using it),
4334 // c) it's empty (this means that it was emptied during
4335 // a cleanup and it should be on the free list now), or
4336 // d) it's humongous (this means that it was emptied
4337 // during a cleanup and was added to the free list, but
4338 // has been subsequently used to allocate a humongous
4339 // object that may be less than the region size).
4340 if (retained_region != NULL &&
4341 !retained_region->in_collection_set() &&
4342 !(retained_region->top() == retained_region->end()) &&
4343 !retained_region->is_empty() &&
4344 !retained_region->isHumongous()) {
4345 retained_region->set_saved_mark();
4346 // The retained region was added to the old region set when it was
4347 // retired. We have to remove it now, since we don't allow regions
4348 // we allocate to in the region sets. We'll re-add it later, when
4349 // it's retired again.
4350 _old_set.remove(retained_region);
4351 bool during_im = g1_policy()->during_initial_mark_pause();
4352 retained_region->note_start_of_copying(during_im);
4353 _old_gc_alloc_region.set(retained_region);
4354 _hr_printer.reuse(retained_region);
4355 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4356 }
4357 }
4358
4359 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4360 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4361 _old_gc_alloc_region.count());
4362 _survivor_gc_alloc_region.release();
4363 // If we have an old GC alloc region to release, we'll save it in
4364 // _retained_old_gc_alloc_region. If we don't
4365 // _retained_old_gc_alloc_region will become NULL. This is what we
4366 // want either way so no reason to check explicitly for either
4367 // condition.
4368 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4369
4370 if (ResizePLAB) {
4371 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4372 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4373 }
4374 }
4375
4376 void G1CollectedHeap::abandon_gc_alloc_regions() {
4377 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4378 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4379 _retained_old_gc_alloc_region = NULL;
4380 }
4381
4382 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4383 _drain_in_progress = false;
4384 set_evac_failure_closure(cl);
4385 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4386 }
4387
4388 void G1CollectedHeap::finalize_for_evac_failure() {
4389 assert(_evac_failure_scan_stack != NULL &&
4390 _evac_failure_scan_stack->length() == 0,
4391 "Postcondition");
4392 assert(!_drain_in_progress, "Postcondition");
4393 delete _evac_failure_scan_stack;
4394 _evac_failure_scan_stack = NULL;
4395 }
4396
4397 void G1CollectedHeap::remove_self_forwarding_pointers() {
4398 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4399
4400 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4401
4402 if (G1CollectedHeap::use_parallel_gc_threads()) {
4403 set_par_threads();
4404 workers()->run_task(&rsfp_task);
4405 set_par_threads(0);
4406 } else {
4407 rsfp_task.work(0);
4408 }
4409
4410 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4411
4412 // Reset the claim values in the regions in the collection set.
4413 reset_cset_heap_region_claim_values();
4414
4415 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4416
4417 // Now restore saved marks, if any.
4418 assert(_objs_with_preserved_marks.size() ==
4419 _preserved_marks_of_objs.size(), "Both or none.");
4420 while (!_objs_with_preserved_marks.is_empty()) {
4421 oop obj = _objs_with_preserved_marks.pop();
4422 markOop m = _preserved_marks_of_objs.pop();
4423 obj->set_mark(m);
4424 }
4425 _objs_with_preserved_marks.clear(true);
4426 _preserved_marks_of_objs.clear(true);
4427 }
4428
4429 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4430 _evac_failure_scan_stack->push(obj);
4431 }
4432
4433 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4434 assert(_evac_failure_scan_stack != NULL, "precondition");
4435
4436 while (_evac_failure_scan_stack->length() > 0) {
4437 oop obj = _evac_failure_scan_stack->pop();
4438 _evac_failure_closure->set_region(heap_region_containing(obj));
4439 obj->oop_iterate_backwards(_evac_failure_closure);
4440 }
4441 }
4442
4443 oop
4444 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4445 oop old) {
4446 assert(obj_in_cs(old),
4447 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4448 (HeapWord*) old));
4449 markOop m = old->mark();
4450 oop forward_ptr = old->forward_to_atomic(old);
4451 if (forward_ptr == NULL) {
4452 // Forward-to-self succeeded.
4453 assert(_par_scan_state != NULL, "par scan state");
4454 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4455 uint queue_num = _par_scan_state->queue_num();
4456
4457 _evacuation_failed = true;
4458 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4459 if (_evac_failure_closure != cl) {
4460 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4461 assert(!_drain_in_progress,
4462 "Should only be true while someone holds the lock.");
4463 // Set the global evac-failure closure to the current thread's.
4464 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4465 set_evac_failure_closure(cl);
4466 // Now do the common part.
4467 handle_evacuation_failure_common(old, m);
4468 // Reset to NULL.
4469 set_evac_failure_closure(NULL);
4470 } else {
4471 // The lock is already held, and this is recursive.
4472 assert(_drain_in_progress, "This should only be the recursive case.");
4473 handle_evacuation_failure_common(old, m);
4474 }
4475 return old;
4476 } else {
4477 // Forward-to-self failed. Either someone else managed to allocate
4478 // space for this object (old != forward_ptr) or they beat us in
4479 // self-forwarding it (old == forward_ptr).
4480 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4481 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4482 "should not be in the CSet",
4483 (HeapWord*) old, (HeapWord*) forward_ptr));
4484 return forward_ptr;
4485 }
4486 }
4487
4488 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4489 preserve_mark_if_necessary(old, m);
4490
4491 HeapRegion* r = heap_region_containing(old);
4492 if (!r->evacuation_failed()) {
4493 r->set_evacuation_failed(true);
4494 _hr_printer.evac_failure(r);
4495 }
4496
4497 push_on_evac_failure_scan_stack(old);
4498
4499 if (!_drain_in_progress) {
4500 // prevent recursion in copy_to_survivor_space()
4501 _drain_in_progress = true;
4502 drain_evac_failure_scan_stack();
4503 _drain_in_progress = false;
4504 }
4505 }
4506
4507 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4508 assert(evacuation_failed(), "Oversaving!");
4509 // We want to call the "for_promotion_failure" version only in the
4510 // case of a promotion failure.
4511 if (m->must_be_preserved_for_promotion_failure(obj)) {
4512 _objs_with_preserved_marks.push(obj);
4513 _preserved_marks_of_objs.push(m);
4514 }
4515 }
4516
4517 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4518 size_t word_size) {
4519 if (purpose == GCAllocForSurvived) {
4520 HeapWord* result = survivor_attempt_allocation(word_size);
4521 if (result != NULL) {
4522 return result;
4523 } else {
4524 // Let's try to allocate in the old gen in case we can fit the
4525 // object there.
4526 return old_attempt_allocation(word_size);
4527 }
4528 } else {
4529 assert(purpose == GCAllocForTenured, "sanity");
4530 HeapWord* result = old_attempt_allocation(word_size);
4531 if (result != NULL) {
4532 return result;
4533 } else {
4534 // Let's try to allocate in the survivors in case we can fit the
4535 // object there.
4536 return survivor_attempt_allocation(word_size);
4537 }
4538 }
4539
4540 ShouldNotReachHere();
4541 // Trying to keep some compilers happy.
4542 return NULL;
4543 }
4544
4545 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4546 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4547
4548 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4549 : _g1h(g1h),
4550 _refs(g1h->task_queue(queue_num)),
4551 _dcq(&g1h->dirty_card_queue_set()),
4552 _ct_bs(g1h->g1_barrier_set()),
4553 _g1_rem(g1h->g1_rem_set()),
4554 _hash_seed(17), _queue_num(queue_num),
4555 _term_attempts(0),
4556 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4557 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4558 _age_table(false),
4559 _strong_roots_time(0), _term_time(0),
4560 _alloc_buffer_waste(0), _undo_waste(0) {
4561 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4562 // we "sacrifice" entry 0 to keep track of surviving bytes for
4563 // non-young regions (where the age is -1)
4564 // We also add a few elements at the beginning and at the end in
4565 // an attempt to eliminate cache contention
4566 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4567 uint array_length = PADDING_ELEM_NUM +
4568 real_length +
4569 PADDING_ELEM_NUM;
4570 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4571 if (_surviving_young_words_base == NULL)
4572 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4573 "Not enough space for young surv histo.");
4574 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4575 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4576
4577 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4578 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4579
4580 _start = os::elapsedTime();
4581 }
4582
4583 void
4584 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4585 {
4586 st->print_raw_cr("GC Termination Stats");
4587 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4588 " ------waste (KiB)------");
4589 st->print_raw_cr("thr ms ms % ms % attempts"
4590 " total alloc undo");
4591 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4592 " ------- ------- -------");
4593 }
4594
4595 void
4596 G1ParScanThreadState::print_termination_stats(int i,
4597 outputStream* const st) const
4598 {
4599 const double elapsed_ms = elapsed_time() * 1000.0;
4600 const double s_roots_ms = strong_roots_time() * 1000.0;
4601 const double term_ms = term_time() * 1000.0;
4602 st->print_cr("%3d %9.2f %9.2f %6.2f "
4603 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4604 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4605 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4606 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4607 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4608 alloc_buffer_waste() * HeapWordSize / K,
4609 undo_waste() * HeapWordSize / K);
4610 }
4611
4612 #ifdef ASSERT
4613 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4614 assert(ref != NULL, "invariant");
4615 assert(UseCompressedOops, "sanity");
4616 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4617 oop p = oopDesc::load_decode_heap_oop(ref);
4618 assert(_g1h->is_in_g1_reserved(p),
4619 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4620 return true;
4621 }
4622
4623 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4624 assert(ref != NULL, "invariant");
4625 if (has_partial_array_mask(ref)) {
4626 // Must be in the collection set--it's already been copied.
4627 oop p = clear_partial_array_mask(ref);
4628 assert(_g1h->obj_in_cs(p),
4629 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4630 } else {
4631 oop p = oopDesc::load_decode_heap_oop(ref);
4632 assert(_g1h->is_in_g1_reserved(p),
4633 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4634 }
4635 return true;
4636 }
4637
4638 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4639 if (ref.is_narrow()) {
4640 return verify_ref((narrowOop*) ref);
4641 } else {
4642 return verify_ref((oop*) ref);
4643 }
4644 }
4645 #endif // ASSERT
4646
4647 void G1ParScanThreadState::trim_queue() {
4648 assert(_evac_cl != NULL, "not set");
4649 assert(_evac_failure_cl != NULL, "not set");
4650 assert(_partial_scan_cl != NULL, "not set");
4651
4652 StarTask ref;
4653 do {
4654 // Drain the overflow stack first, so other threads can steal.
4655 while (refs()->pop_overflow(ref)) {
4656 deal_with_reference(ref);
4657 }
4658
4659 while (refs()->pop_local(ref)) {
4660 deal_with_reference(ref);
4661 }
4662 } while (!refs()->is_empty());
4663 }
4664
4665 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4666 G1ParScanThreadState* par_scan_state) :
4667 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4668 _par_scan_state(par_scan_state),
4669 _worker_id(par_scan_state->queue_num()),
4670 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4671 _mark_in_progress(_g1->mark_in_progress()) { }
4672
4673 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4674 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4675 #ifdef ASSERT
4676 HeapRegion* hr = _g1->heap_region_containing(obj);
4677 assert(hr != NULL, "sanity");
4678 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4679 #endif // ASSERT
4680
4681 // We know that the object is not moving so it's safe to read its size.
4682 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4683 }
4684
4685 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4686 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4687 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4688 #ifdef ASSERT
4689 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4690 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4691 assert(from_obj != to_obj, "should not be self-forwarded");
4692
4693 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4694 assert(from_hr != NULL, "sanity");
4695 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4696
4697 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4698 assert(to_hr != NULL, "sanity");
4699 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4700 #endif // ASSERT
4701
4702 // The object might be in the process of being copied by another
4703 // worker so we cannot trust that its to-space image is
4704 // well-formed. So we have to read its size from its from-space
4705 // image which we know should not be changing.
4706 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4707 }
4708
4709 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4710 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4711 ::copy_to_survivor_space(oop old) {
4712 size_t word_sz = old->size();
4713 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4714 // +1 to make the -1 indexes valid...
4715 int young_index = from_region->young_index_in_cset()+1;
4716 assert( (from_region->is_young() && young_index > 0) ||
4717 (!from_region->is_young() && young_index == 0), "invariant" );
4718 G1CollectorPolicy* g1p = _g1->g1_policy();
4719 markOop m = old->mark();
4720 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4721 : m->age();
4722 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4723 word_sz);
4724 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4725 #ifndef PRODUCT
4726 // Should this evacuation fail?
4727 if (_g1->evacuation_should_fail()) {
4728 if (obj_ptr != NULL) {
4729 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4730 obj_ptr = NULL;
4731 }
4732 }
4733 #endif // !PRODUCT
4734
4735 if (obj_ptr == NULL) {
4736 // This will either forward-to-self, or detect that someone else has
4737 // installed a forwarding pointer.
4738 return _g1->handle_evacuation_failure_par(_par_scan_state, old);
4739 }
4740
4741 oop obj = oop(obj_ptr);
4742
4743 // We're going to allocate linearly, so might as well prefetch ahead.
4744 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4745
4746 oop forward_ptr = old->forward_to_atomic(obj);
4747 if (forward_ptr == NULL) {
4748 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4749 if (g1p->track_object_age(alloc_purpose)) {
4750 // We could simply do obj->incr_age(). However, this causes a
4751 // performance issue. obj->incr_age() will first check whether
4752 // the object has a displaced mark by checking its mark word;
4753 // getting the mark word from the new location of the object
4754 // stalls. So, given that we already have the mark word and we
4755 // are about to install it anyway, it's better to increase the
4756 // age on the mark word, when the object does not have a
4757 // displaced mark word. We're not expecting many objects to have
4758 // a displaced marked word, so that case is not optimized
4759 // further (it could be...) and we simply call obj->incr_age().
4760
4761 if (m->has_displaced_mark_helper()) {
4762 // in this case, we have to install the mark word first,
4763 // otherwise obj looks to be forwarded (the old mark word,
4764 // which contains the forward pointer, was copied)
4765 obj->set_mark(m);
4766 obj->incr_age();
4767 } else {
4768 m = m->incr_age();
4769 obj->set_mark(m);
4770 }
4771 _par_scan_state->age_table()->add(obj, word_sz);
4772 } else {
4773 obj->set_mark(m);
4774 }
4775
4776 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4777 surv_young_words[young_index] += word_sz;
4778
4779 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4780 // We keep track of the next start index in the length field of
4781 // the to-space object. The actual length can be found in the
4782 // length field of the from-space object.
4783 arrayOop(obj)->set_length(0);
4784 oop* old_p = set_partial_array_mask(old);
4785 _par_scan_state->push_on_queue(old_p);
4786 } else {
4787 // No point in using the slower heap_region_containing() method,
4788 // given that we know obj is in the heap.
4789 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4790 obj->oop_iterate_backwards(&_scanner);
4791 }
4792 } else {
4793 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4794 obj = forward_ptr;
4795 }
4796 return obj;
4797 }
4798
4799 template <class T>
4800 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4801 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4802 _scanned_klass->record_modified_oops();
4803 }
4804 }
4805
4806 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4807 template <class T>
4808 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4809 ::do_oop_work(T* p) {
4810 oop obj = oopDesc::load_decode_heap_oop(p);
4811 assert(barrier != G1BarrierRS || obj != NULL,
4812 "Precondition: G1BarrierRS implies obj is non-NULL");
4813
4814 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4815
4816 // here the null check is implicit in the cset_fast_test() test
4817 if (_g1->in_cset_fast_test(obj)) {
4818 oop forwardee;
4819 if (obj->is_forwarded()) {
4820 forwardee = obj->forwardee();
4821 } else {
4822 forwardee = copy_to_survivor_space(obj);
4823 }
4824 assert(forwardee != NULL, "forwardee should not be NULL");
4825 oopDesc::encode_store_heap_oop(p, forwardee);
4826 if (do_mark_object && forwardee != obj) {
4827 // If the object is self-forwarded we don't need to explicitly
4828 // mark it, the evacuation failure protocol will do so.
4829 mark_forwarded_object(obj, forwardee);
4830 }
4831
4832 // When scanning the RS, we only care about objs in CS.
4833 if (barrier == G1BarrierRS) {
4834 _par_scan_state->update_rs(_from, p, _worker_id);
4835 } else if (barrier == G1BarrierKlass) {
4836 do_klass_barrier(p, forwardee);
4837 }
4838 } else {
4839 // The object is not in collection set. If we're a root scanning
4840 // closure during an initial mark pause (i.e. do_mark_object will
4841 // be true) then attempt to mark the object.
4842 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4843 mark_object(obj);
4844 }
4845 }
4846
4847 if (barrier == G1BarrierEvac && obj != NULL) {
4848 _par_scan_state->update_rs(_from, p, _worker_id);
4849 }
4850
4851 if (do_gen_barrier && obj != NULL) {
4852 par_do_barrier(p);
4853 }
4854 }
4855
4856 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4857 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4858
4859 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4860 assert(has_partial_array_mask(p), "invariant");
4861 oop from_obj = clear_partial_array_mask(p);
4862
4863 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4864 assert(from_obj->is_objArray(), "must be obj array");
4865 objArrayOop from_obj_array = objArrayOop(from_obj);
4866 // The from-space object contains the real length.
4867 int length = from_obj_array->length();
4868
4869 assert(from_obj->is_forwarded(), "must be forwarded");
4870 oop to_obj = from_obj->forwardee();
4871 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4872 objArrayOop to_obj_array = objArrayOop(to_obj);
4873 // We keep track of the next start index in the length field of the
4874 // to-space object.
4875 int next_index = to_obj_array->length();
4876 assert(0 <= next_index && next_index < length,
4877 err_msg("invariant, next index: %d, length: %d", next_index, length));
4878
4879 int start = next_index;
4880 int end = length;
4881 int remainder = end - start;
4882 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4883 if (remainder > 2 * ParGCArrayScanChunk) {
4884 end = start + ParGCArrayScanChunk;
4885 to_obj_array->set_length(end);
4886 // Push the remainder before we process the range in case another
4887 // worker has run out of things to do and can steal it.
4888 oop* from_obj_p = set_partial_array_mask(from_obj);
4889 _par_scan_state->push_on_queue(from_obj_p);
4890 } else {
4891 assert(length == end, "sanity");
4892 // We'll process the final range for this object. Restore the length
4893 // so that the heap remains parsable in case of evacuation failure.
4894 to_obj_array->set_length(end);
4895 }
4896 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4897 // Process indexes [start,end). It will also process the header
4898 // along with the first chunk (i.e., the chunk with start == 0).
4899 // Note that at this point the length field of to_obj_array is not
4900 // correct given that we are using it to keep track of the next
4901 // start index. oop_iterate_range() (thankfully!) ignores the length
4902 // field and only relies on the start / end parameters. It does
4903 // however return the size of the object which will be incorrect. So
4904 // we have to ignore it even if we wanted to use it.
4905 to_obj_array->oop_iterate_range(&_scanner, start, end);
4906 }
4907
4908 class G1ParEvacuateFollowersClosure : public VoidClosure {
4909 protected:
4910 G1CollectedHeap* _g1h;
4911 G1ParScanThreadState* _par_scan_state;
4912 RefToScanQueueSet* _queues;
4913 ParallelTaskTerminator* _terminator;
4914
4915 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4916 RefToScanQueueSet* queues() { return _queues; }
4917 ParallelTaskTerminator* terminator() { return _terminator; }
4918
4919 public:
4920 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4921 G1ParScanThreadState* par_scan_state,
4922 RefToScanQueueSet* queues,
4923 ParallelTaskTerminator* terminator)
4924 : _g1h(g1h), _par_scan_state(par_scan_state),
4925 _queues(queues), _terminator(terminator) {}
4926
4927 void do_void();
4928
4929 private:
4930 inline bool offer_termination();
4931 };
4932
4933 bool G1ParEvacuateFollowersClosure::offer_termination() {
4934 G1ParScanThreadState* const pss = par_scan_state();
4935 pss->start_term_time();
4936 const bool res = terminator()->offer_termination();
4937 pss->end_term_time();
4938 return res;
4939 }
4940
4941 void G1ParEvacuateFollowersClosure::do_void() {
4942 StarTask stolen_task;
4943 G1ParScanThreadState* const pss = par_scan_state();
4944 pss->trim_queue();
4945
4946 do {
4947 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4948 assert(pss->verify_task(stolen_task), "sanity");
4949 if (stolen_task.is_narrow()) {
4950 pss->deal_with_reference((narrowOop*) stolen_task);
4951 } else {
4952 pss->deal_with_reference((oop*) stolen_task);
4953 }
4954
4955 // We've just processed a reference and we might have made
4956 // available new entries on the queues. So we have to make sure
4957 // we drain the queues as necessary.
4958 pss->trim_queue();
4959 }
4960 } while (!offer_termination());
4961
4962 pss->retire_alloc_buffers();
4963 }
4964
4965 class G1KlassScanClosure : public KlassClosure {
4966 G1ParCopyHelper* _closure;
4967 bool _process_only_dirty;
4968 int _count;
4969 public:
4970 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4971 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4972 void do_klass(Klass* klass) {
4973 // If the klass has not been dirtied we know that there's
4974 // no references into the young gen and we can skip it.
4975 if (!_process_only_dirty || klass->has_modified_oops()) {
4976 // Clean the klass since we're going to scavenge all the metadata.
4977 klass->clear_modified_oops();
4978
4979 // Tell the closure that this klass is the Klass to scavenge
4980 // and is the one to dirty if oops are left pointing into the young gen.
4981 _closure->set_scanned_klass(klass);
4982
4983 klass->oops_do(_closure);
4984
4985 _closure->set_scanned_klass(NULL);
4986 }
4987 _count++;
4988 }
4989 };
4990
4991 class G1ParTask : public AbstractGangTask {
4992 protected:
4993 G1CollectedHeap* _g1h;
4994 RefToScanQueueSet *_queues;
4995 ParallelTaskTerminator _terminator;
4996 uint _n_workers;
4997
4998 Mutex _stats_lock;
4999 Mutex* stats_lock() { return &_stats_lock; }
5000
5001 size_t getNCards() {
5002 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
5003 / G1BlockOffsetSharedArray::N_bytes;
5004 }
5005
5006 public:
5007 G1ParTask(G1CollectedHeap* g1h,
5008 RefToScanQueueSet *task_queues)
5009 : AbstractGangTask("G1 collection"),
5010 _g1h(g1h),
5011 _queues(task_queues),
5012 _terminator(0, _queues),
5013 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
5014 {}
5015
5016 RefToScanQueueSet* queues() { return _queues; }
5017
5018 RefToScanQueue *work_queue(int i) {
5019 return queues()->queue(i);
5020 }
5021
5022 ParallelTaskTerminator* terminator() { return &_terminator; }
5023
5024 virtual void set_for_termination(int active_workers) {
5025 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
5026 // in the young space (_par_seq_tasks) in the G1 heap
5027 // for SequentialSubTasksDone.
5028 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
5029 // both of which need setting by set_n_termination().
5030 _g1h->SharedHeap::set_n_termination(active_workers);
5031 _g1h->set_n_termination(active_workers);
5032 terminator()->reset_for_reuse(active_workers);
5033 _n_workers = active_workers;
5034 }
5035
5036 void work(uint worker_id) {
5037 if (worker_id >= _n_workers) return; // no work needed this round
5038
5039 double start_time_ms = os::elapsedTime() * 1000.0;
5040 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5041
5042 {
5043 ResourceMark rm;
5044 HandleMark hm;
5045
5046 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5047
5048 G1ParScanThreadState pss(_g1h, worker_id);
5049 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
5050 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5051 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
5052
5053 pss.set_evac_closure(&scan_evac_cl);
5054 pss.set_evac_failure_closure(&evac_failure_cl);
5055 pss.set_partial_scan_closure(&partial_scan_cl);
5056
5057 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5058 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5059
5060 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5061 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5062
5063 bool only_young = _g1h->g1_policy()->gcs_are_young();
5064 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5065 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5066
5067 OopClosure* scan_root_cl = &only_scan_root_cl;
5068 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5069
5070 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5071 // We also need to mark copied objects.
5072 scan_root_cl = &scan_mark_root_cl;
5073 scan_klasses_cl = &scan_mark_klasses_cl_s;
5074 }
5075
5076 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5077
5078 // Don't scan the scavengable methods in the code cache as part
5079 // of strong root scanning. The code roots that point into a
5080 // region in the collection set are scanned when we scan the
5081 // region's RSet.
5082 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5083
5084 pss.start_strong_roots();
5085 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5086 SharedHeap::ScanningOption(so),
5087 scan_root_cl,
5088 &push_heap_rs_cl,
5089 scan_klasses_cl,
5090 worker_id);
5091 pss.end_strong_roots();
5092
5093 {
5094 double start = os::elapsedTime();
5095 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5096 evac.do_void();
5097 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5098 double term_ms = pss.term_time()*1000.0;
5099 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5100 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5101 }
5102 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5103 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5104
5105 if (ParallelGCVerbose) {
5106 MutexLocker x(stats_lock());
5107 pss.print_termination_stats(worker_id);
5108 }
5109
5110 assert(pss.refs()->is_empty(), "should be empty");
5111
5112 // Close the inner scope so that the ResourceMark and HandleMark
5113 // destructors are executed here and are included as part of the
5114 // "GC Worker Time".
5115 }
5116
5117 double end_time_ms = os::elapsedTime() * 1000.0;
5118 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5119 }
5120 };
5121
5122 // *** Common G1 Evacuation Stuff
5123
5124 // This method is run in a GC worker.
5125
5126 void
5127 G1CollectedHeap::
5128 g1_process_strong_roots(bool is_scavenging,
5129 ScanningOption so,
5130 OopClosure* scan_non_heap_roots,
5131 OopsInHeapRegionClosure* scan_rs,
5132 G1KlassScanClosure* scan_klasses,
5133 int worker_i) {
5134
5135 // First scan the strong roots
5136 double ext_roots_start = os::elapsedTime();
5137 double closure_app_time_sec = 0.0;
5138
5139 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5140
5141 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5142 // Walk the code cache/strong code roots w/o buffering, because StarTask
5143 // cannot handle unaligned oop locations.
5144 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5145
5146 process_strong_roots(false, // no scoping; this is parallel code
5147 is_scavenging, so,
5148 &buf_scan_non_heap_roots,
5149 &eager_scan_code_roots,
5150 scan_klasses
5151 );
5152
5153 // Now the CM ref_processor roots.
5154 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5155 // We need to treat the discovered reference lists of the
5156 // concurrent mark ref processor as roots and keep entries
5157 // (which are added by the marking threads) on them live
5158 // until they can be processed at the end of marking.
5159 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5160 }
5161
5162 // Finish up any enqueued closure apps (attributed as object copy time).
5163 buf_scan_non_heap_roots.done();
5164
5165 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5166
5167 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5168
5169 double ext_root_time_ms =
5170 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5171
5172 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5173
5174 // During conc marking we have to filter the per-thread SATB buffers
5175 // to make sure we remove any oops into the CSet (which will show up
5176 // as implicitly live).
5177 double satb_filtering_ms = 0.0;
5178 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5179 if (mark_in_progress()) {
5180 double satb_filter_start = os::elapsedTime();
5181
5182 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5183
5184 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5185 }
5186 }
5187 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5188
5189 // If this is an initial mark pause, and we're not scanning
5190 // the entire code cache, we need to mark the oops in the
5191 // strong code root lists for the regions that are not in
5192 // the collection set.
5193 // Note all threads participate in this set of root tasks.
5194 double mark_strong_code_roots_ms = 0.0;
5195 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5196 double mark_strong_roots_start = os::elapsedTime();
5197 mark_strong_code_roots(worker_i);
5198 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5199 }
5200 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5201
5202 // Now scan the complement of the collection set.
5203 if (scan_rs != NULL) {
5204 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5205 }
5206 _process_strong_tasks->all_tasks_completed();
5207 }
5208
5209 void
5210 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5211 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5212 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5213 }
5214
5215 // Weak Reference Processing support
5216
5217 // An always "is_alive" closure that is used to preserve referents.
5218 // If the object is non-null then it's alive. Used in the preservation
5219 // of referent objects that are pointed to by reference objects
5220 // discovered by the CM ref processor.
5221 class G1AlwaysAliveClosure: public BoolObjectClosure {
5222 G1CollectedHeap* _g1;
5223 public:
5224 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5225 bool do_object_b(oop p) {
5226 if (p != NULL) {
5227 return true;
5228 }
5229 return false;
5230 }
5231 };
5232
5233 bool G1STWIsAliveClosure::do_object_b(oop p) {
5234 // An object is reachable if it is outside the collection set,
5235 // or is inside and copied.
5236 return !_g1->obj_in_cs(p) || p->is_forwarded();
5237 }
5238
5239 // Non Copying Keep Alive closure
5240 class G1KeepAliveClosure: public OopClosure {
5241 G1CollectedHeap* _g1;
5242 public:
5243 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5244 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5245 void do_oop( oop* p) {
5246 oop obj = *p;
5247
5248 if (_g1->obj_in_cs(obj)) {
5249 assert( obj->is_forwarded(), "invariant" );
5250 *p = obj->forwardee();
5251 }
5252 }
5253 };
5254
5255 // Copying Keep Alive closure - can be called from both
5256 // serial and parallel code as long as different worker
5257 // threads utilize different G1ParScanThreadState instances
5258 // and different queues.
5259
5260 class G1CopyingKeepAliveClosure: public OopClosure {
5261 G1CollectedHeap* _g1h;
5262 OopClosure* _copy_non_heap_obj_cl;
5263 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5264 G1ParScanThreadState* _par_scan_state;
5265
5266 public:
5267 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5268 OopClosure* non_heap_obj_cl,
5269 OopsInHeapRegionClosure* metadata_obj_cl,
5270 G1ParScanThreadState* pss):
5271 _g1h(g1h),
5272 _copy_non_heap_obj_cl(non_heap_obj_cl),
5273 _copy_metadata_obj_cl(metadata_obj_cl),
5274 _par_scan_state(pss)
5275 {}
5276
5277 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5278 virtual void do_oop( oop* p) { do_oop_work(p); }
5279
5280 template <class T> void do_oop_work(T* p) {
5281 oop obj = oopDesc::load_decode_heap_oop(p);
5282
5283 if (_g1h->obj_in_cs(obj)) {
5284 // If the referent object has been forwarded (either copied
5285 // to a new location or to itself in the event of an
5286 // evacuation failure) then we need to update the reference
5287 // field and, if both reference and referent are in the G1
5288 // heap, update the RSet for the referent.
5289 //
5290 // If the referent has not been forwarded then we have to keep
5291 // it alive by policy. Therefore we have copy the referent.
5292 //
5293 // If the reference field is in the G1 heap then we can push
5294 // on the PSS queue. When the queue is drained (after each
5295 // phase of reference processing) the object and it's followers
5296 // will be copied, the reference field set to point to the
5297 // new location, and the RSet updated. Otherwise we need to
5298 // use the the non-heap or metadata closures directly to copy
5299 // the referent object and update the pointer, while avoiding
5300 // updating the RSet.
5301
5302 if (_g1h->is_in_g1_reserved(p)) {
5303 _par_scan_state->push_on_queue(p);
5304 } else {
5305 assert(!ClassLoaderDataGraph::contains((address)p),
5306 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5307 PTR_FORMAT, p));
5308 _copy_non_heap_obj_cl->do_oop(p);
5309 }
5310 }
5311 }
5312 };
5313
5314 // Serial drain queue closure. Called as the 'complete_gc'
5315 // closure for each discovered list in some of the
5316 // reference processing phases.
5317
5318 class G1STWDrainQueueClosure: public VoidClosure {
5319 protected:
5320 G1CollectedHeap* _g1h;
5321 G1ParScanThreadState* _par_scan_state;
5322
5323 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5324
5325 public:
5326 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5327 _g1h(g1h),
5328 _par_scan_state(pss)
5329 { }
5330
5331 void do_void() {
5332 G1ParScanThreadState* const pss = par_scan_state();
5333 pss->trim_queue();
5334 }
5335 };
5336
5337 // Parallel Reference Processing closures
5338
5339 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5340 // processing during G1 evacuation pauses.
5341
5342 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5343 private:
5344 G1CollectedHeap* _g1h;
5345 RefToScanQueueSet* _queues;
5346 FlexibleWorkGang* _workers;
5347 int _active_workers;
5348
5349 public:
5350 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5351 FlexibleWorkGang* workers,
5352 RefToScanQueueSet *task_queues,
5353 int n_workers) :
5354 _g1h(g1h),
5355 _queues(task_queues),
5356 _workers(workers),
5357 _active_workers(n_workers)
5358 {
5359 assert(n_workers > 0, "shouldn't call this otherwise");
5360 }
5361
5362 // Executes the given task using concurrent marking worker threads.
5363 virtual void execute(ProcessTask& task);
5364 virtual void execute(EnqueueTask& task);
5365 };
5366
5367 // Gang task for possibly parallel reference processing
5368
5369 class G1STWRefProcTaskProxy: public AbstractGangTask {
5370 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5371 ProcessTask& _proc_task;
5372 G1CollectedHeap* _g1h;
5373 RefToScanQueueSet *_task_queues;
5374 ParallelTaskTerminator* _terminator;
5375
5376 public:
5377 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5378 G1CollectedHeap* g1h,
5379 RefToScanQueueSet *task_queues,
5380 ParallelTaskTerminator* terminator) :
5381 AbstractGangTask("Process reference objects in parallel"),
5382 _proc_task(proc_task),
5383 _g1h(g1h),
5384 _task_queues(task_queues),
5385 _terminator(terminator)
5386 {}
5387
5388 virtual void work(uint worker_id) {
5389 // The reference processing task executed by a single worker.
5390 ResourceMark rm;
5391 HandleMark hm;
5392
5393 G1STWIsAliveClosure is_alive(_g1h);
5394
5395 G1ParScanThreadState pss(_g1h, worker_id);
5396
5397 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5398 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5399 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5400
5401 pss.set_evac_closure(&scan_evac_cl);
5402 pss.set_evac_failure_closure(&evac_failure_cl);
5403 pss.set_partial_scan_closure(&partial_scan_cl);
5404
5405 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5406 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5407
5408 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5409 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5410
5411 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5412 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5413
5414 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5415 // We also need to mark copied objects.
5416 copy_non_heap_cl = ©_mark_non_heap_cl;
5417 copy_metadata_cl = ©_mark_metadata_cl;
5418 }
5419
5420 // Keep alive closure.
5421 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5422
5423 // Complete GC closure
5424 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5425
5426 // Call the reference processing task's work routine.
5427 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5428
5429 // Note we cannot assert that the refs array is empty here as not all
5430 // of the processing tasks (specifically phase2 - pp2_work) execute
5431 // the complete_gc closure (which ordinarily would drain the queue) so
5432 // the queue may not be empty.
5433 }
5434 };
5435
5436 // Driver routine for parallel reference processing.
5437 // Creates an instance of the ref processing gang
5438 // task and has the worker threads execute it.
5439 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5440 assert(_workers != NULL, "Need parallel worker threads.");
5441
5442 ParallelTaskTerminator terminator(_active_workers, _queues);
5443 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5444
5445 _g1h->set_par_threads(_active_workers);
5446 _workers->run_task(&proc_task_proxy);
5447 _g1h->set_par_threads(0);
5448 }
5449
5450 // Gang task for parallel reference enqueueing.
5451
5452 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5453 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5454 EnqueueTask& _enq_task;
5455
5456 public:
5457 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5458 AbstractGangTask("Enqueue reference objects in parallel"),
5459 _enq_task(enq_task)
5460 { }
5461
5462 virtual void work(uint worker_id) {
5463 _enq_task.work(worker_id);
5464 }
5465 };
5466
5467 // Driver routine for parallel reference enqueueing.
5468 // Creates an instance of the ref enqueueing gang
5469 // task and has the worker threads execute it.
5470
5471 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5472 assert(_workers != NULL, "Need parallel worker threads.");
5473
5474 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5475
5476 _g1h->set_par_threads(_active_workers);
5477 _workers->run_task(&enq_task_proxy);
5478 _g1h->set_par_threads(0);
5479 }
5480
5481 // End of weak reference support closures
5482
5483 // Abstract task used to preserve (i.e. copy) any referent objects
5484 // that are in the collection set and are pointed to by reference
5485 // objects discovered by the CM ref processor.
5486
5487 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5488 protected:
5489 G1CollectedHeap* _g1h;
5490 RefToScanQueueSet *_queues;
5491 ParallelTaskTerminator _terminator;
5492 uint _n_workers;
5493
5494 public:
5495 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5496 AbstractGangTask("ParPreserveCMReferents"),
5497 _g1h(g1h),
5498 _queues(task_queues),
5499 _terminator(workers, _queues),
5500 _n_workers(workers)
5501 { }
5502
5503 void work(uint worker_id) {
5504 ResourceMark rm;
5505 HandleMark hm;
5506
5507 G1ParScanThreadState pss(_g1h, worker_id);
5508 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5509 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5510 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5511
5512 pss.set_evac_closure(&scan_evac_cl);
5513 pss.set_evac_failure_closure(&evac_failure_cl);
5514 pss.set_partial_scan_closure(&partial_scan_cl);
5515
5516 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5517
5518
5519 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5520 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5521
5522 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5523 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5524
5525 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5526 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5527
5528 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5529 // We also need to mark copied objects.
5530 copy_non_heap_cl = ©_mark_non_heap_cl;
5531 copy_metadata_cl = ©_mark_metadata_cl;
5532 }
5533
5534 // Is alive closure
5535 G1AlwaysAliveClosure always_alive(_g1h);
5536
5537 // Copying keep alive closure. Applied to referent objects that need
5538 // to be copied.
5539 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5540
5541 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5542
5543 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5544 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5545
5546 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5547 // So this must be true - but assert just in case someone decides to
5548 // change the worker ids.
5549 assert(0 <= worker_id && worker_id < limit, "sanity");
5550 assert(!rp->discovery_is_atomic(), "check this code");
5551
5552 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5553 for (uint idx = worker_id; idx < limit; idx += stride) {
5554 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5555
5556 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5557 while (iter.has_next()) {
5558 // Since discovery is not atomic for the CM ref processor, we
5559 // can see some null referent objects.
5560 iter.load_ptrs(DEBUG_ONLY(true));
5561 oop ref = iter.obj();
5562
5563 // This will filter nulls.
5564 if (iter.is_referent_alive()) {
5565 iter.make_referent_alive();
5566 }
5567 iter.move_to_next();
5568 }
5569 }
5570
5571 // Drain the queue - which may cause stealing
5572 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5573 drain_queue.do_void();
5574 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5575 assert(pss.refs()->is_empty(), "should be");
5576 }
5577 };
5578
5579 // Weak Reference processing during an evacuation pause (part 1).
5580 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5581 double ref_proc_start = os::elapsedTime();
5582
5583 ReferenceProcessor* rp = _ref_processor_stw;
5584 assert(rp->discovery_enabled(), "should have been enabled");
5585
5586 // Any reference objects, in the collection set, that were 'discovered'
5587 // by the CM ref processor should have already been copied (either by
5588 // applying the external root copy closure to the discovered lists, or
5589 // by following an RSet entry).
5590 //
5591 // But some of the referents, that are in the collection set, that these
5592 // reference objects point to may not have been copied: the STW ref
5593 // processor would have seen that the reference object had already
5594 // been 'discovered' and would have skipped discovering the reference,
5595 // but would not have treated the reference object as a regular oop.
5596 // As a result the copy closure would not have been applied to the
5597 // referent object.
5598 //
5599 // We need to explicitly copy these referent objects - the references
5600 // will be processed at the end of remarking.
5601 //
5602 // We also need to do this copying before we process the reference
5603 // objects discovered by the STW ref processor in case one of these
5604 // referents points to another object which is also referenced by an
5605 // object discovered by the STW ref processor.
5606
5607 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5608 no_of_gc_workers == workers()->active_workers(),
5609 "Need to reset active GC workers");
5610
5611 set_par_threads(no_of_gc_workers);
5612 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5613 no_of_gc_workers,
5614 _task_queues);
5615
5616 if (G1CollectedHeap::use_parallel_gc_threads()) {
5617 workers()->run_task(&keep_cm_referents);
5618 } else {
5619 keep_cm_referents.work(0);
5620 }
5621
5622 set_par_threads(0);
5623
5624 // Closure to test whether a referent is alive.
5625 G1STWIsAliveClosure is_alive(this);
5626
5627 // Even when parallel reference processing is enabled, the processing
5628 // of JNI refs is serial and performed serially by the current thread
5629 // rather than by a worker. The following PSS will be used for processing
5630 // JNI refs.
5631
5632 // Use only a single queue for this PSS.
5633 G1ParScanThreadState pss(this, 0);
5634
5635 // We do not embed a reference processor in the copying/scanning
5636 // closures while we're actually processing the discovered
5637 // reference objects.
5638 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5639 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5640 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5641
5642 pss.set_evac_closure(&scan_evac_cl);
5643 pss.set_evac_failure_closure(&evac_failure_cl);
5644 pss.set_partial_scan_closure(&partial_scan_cl);
5645
5646 assert(pss.refs()->is_empty(), "pre-condition");
5647
5648 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5649 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5650
5651 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5652 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5653
5654 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5655 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5656
5657 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5658 // We also need to mark copied objects.
5659 copy_non_heap_cl = ©_mark_non_heap_cl;
5660 copy_metadata_cl = ©_mark_metadata_cl;
5661 }
5662
5663 // Keep alive closure.
5664 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5665
5666 // Serial Complete GC closure
5667 G1STWDrainQueueClosure drain_queue(this, &pss);
5668
5669 // Setup the soft refs policy...
5670 rp->setup_policy(false);
5671
5672 ReferenceProcessorStats stats;
5673 if (!rp->processing_is_mt()) {
5674 // Serial reference processing...
5675 stats = rp->process_discovered_references(&is_alive,
5676 &keep_alive,
5677 &drain_queue,
5678 NULL,
5679 _gc_timer_stw);
5680 } else {
5681 // Parallel reference processing
5682 assert(rp->num_q() == no_of_gc_workers, "sanity");
5683 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5684
5685 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5686 stats = rp->process_discovered_references(&is_alive,
5687 &keep_alive,
5688 &drain_queue,
5689 &par_task_executor,
5690 _gc_timer_stw);
5691 }
5692
5693 _gc_tracer_stw->report_gc_reference_stats(stats);
5694 // We have completed copying any necessary live referent objects
5695 // (that were not copied during the actual pause) so we can
5696 // retire any active alloc buffers
5697 pss.retire_alloc_buffers();
5698 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5699
5700 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5701 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5702 }
5703
5704 // Weak Reference processing during an evacuation pause (part 2).
5705 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5706 double ref_enq_start = os::elapsedTime();
5707
5708 ReferenceProcessor* rp = _ref_processor_stw;
5709 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5710
5711 // Now enqueue any remaining on the discovered lists on to
5712 // the pending list.
5713 if (!rp->processing_is_mt()) {
5714 // Serial reference processing...
5715 rp->enqueue_discovered_references();
5716 } else {
5717 // Parallel reference enqueueing
5718
5719 assert(no_of_gc_workers == workers()->active_workers(),
5720 "Need to reset active workers");
5721 assert(rp->num_q() == no_of_gc_workers, "sanity");
5722 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5723
5724 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5725 rp->enqueue_discovered_references(&par_task_executor);
5726 }
5727
5728 rp->verify_no_references_recorded();
5729 assert(!rp->discovery_enabled(), "should have been disabled");
5730
5731 // FIXME
5732 // CM's reference processing also cleans up the string and symbol tables.
5733 // Should we do that here also? We could, but it is a serial operation
5734 // and could significantly increase the pause time.
5735
5736 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5737 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5738 }
5739
5740 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5741 _expand_heap_after_alloc_failure = true;
5742 _evacuation_failed = false;
5743
5744 // Should G1EvacuationFailureALot be in effect for this GC?
5745 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5746
5747 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5748
5749 // Disable the hot card cache.
5750 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5751 hot_card_cache->reset_hot_cache_claimed_index();
5752 hot_card_cache->set_use_cache(false);
5753
5754 uint n_workers;
5755 if (G1CollectedHeap::use_parallel_gc_threads()) {
5756 n_workers =
5757 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5758 workers()->active_workers(),
5759 Threads::number_of_non_daemon_threads());
5760 assert(UseDynamicNumberOfGCThreads ||
5761 n_workers == workers()->total_workers(),
5762 "If not dynamic should be using all the workers");
5763 workers()->set_active_workers(n_workers);
5764 set_par_threads(n_workers);
5765 } else {
5766 assert(n_par_threads() == 0,
5767 "Should be the original non-parallel value");
5768 n_workers = 1;
5769 }
5770
5771 G1ParTask g1_par_task(this, _task_queues);
5772
5773 init_for_evac_failure(NULL);
5774
5775 rem_set()->prepare_for_younger_refs_iterate(true);
5776
5777 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5778 double start_par_time_sec = os::elapsedTime();
5779 double end_par_time_sec;
5780
5781 {
5782 StrongRootsScope srs(this);
5783
5784 if (G1CollectedHeap::use_parallel_gc_threads()) {
5785 // The individual threads will set their evac-failure closures.
5786 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5787 // These tasks use ShareHeap::_process_strong_tasks
5788 assert(UseDynamicNumberOfGCThreads ||
5789 workers()->active_workers() == workers()->total_workers(),
5790 "If not dynamic should be using all the workers");
5791 workers()->run_task(&g1_par_task);
5792 } else {
5793 g1_par_task.set_for_termination(n_workers);
5794 g1_par_task.work(0);
5795 }
5796 end_par_time_sec = os::elapsedTime();
5797
5798 // Closing the inner scope will execute the destructor
5799 // for the StrongRootsScope object. We record the current
5800 // elapsed time before closing the scope so that time
5801 // taken for the SRS destructor is NOT included in the
5802 // reported parallel time.
5803 }
5804
5805 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5806 g1_policy()->phase_times()->record_par_time(par_time_ms);
5807
5808 double code_root_fixup_time_ms =
5809 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5810 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5811
5812 set_par_threads(0);
5813
5814 // Process any discovered reference objects - we have
5815 // to do this _before_ we retire the GC alloc regions
5816 // as we may have to copy some 'reachable' referent
5817 // objects (and their reachable sub-graphs) that were
5818 // not copied during the pause.
5819 process_discovered_references(n_workers);
5820
5821 // Weak root processing.
5822 {
5823 G1STWIsAliveClosure is_alive(this);
5824 G1KeepAliveClosure keep_alive(this);
5825 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5826 }
5827
5828 release_gc_alloc_regions(n_workers, evacuation_info);
5829 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5830
5831 // Reset and re-enable the hot card cache.
5832 // Note the counts for the cards in the regions in the
5833 // collection set are reset when the collection set is freed.
5834 hot_card_cache->reset_hot_cache();
5835 hot_card_cache->set_use_cache(true);
5836
5837 // Migrate the strong code roots attached to each region in
5838 // the collection set. Ideally we would like to do this
5839 // after we have finished the scanning/evacuation of the
5840 // strong code roots for a particular heap region.
5841 migrate_strong_code_roots();
5842
5843 if (g1_policy()->during_initial_mark_pause()) {
5844 // Reset the claim values set during marking the strong code roots
5845 reset_heap_region_claim_values();
5846 }
5847
5848 finalize_for_evac_failure();
5849
5850 if (evacuation_failed()) {
5851 remove_self_forwarding_pointers();
5852
5853 // Reset the G1EvacuationFailureALot counters and flags
5854 // Note: the values are reset only when an actual
5855 // evacuation failure occurs.
5856 NOT_PRODUCT(reset_evacuation_should_fail();)
5857 }
5858
5859 // Enqueue any remaining references remaining on the STW
5860 // reference processor's discovered lists. We need to do
5861 // this after the card table is cleaned (and verified) as
5862 // the act of enqueueing entries on to the pending list
5863 // will log these updates (and dirty their associated
5864 // cards). We need these updates logged to update any
5865 // RSets.
5866 enqueue_discovered_references(n_workers);
5867
5868 if (G1DeferredRSUpdate) {
5869 RedirtyLoggedCardTableEntryFastClosure redirty;
5870 dirty_card_queue_set().set_closure(&redirty);
5871 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5872
5873 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5874 dcq.merge_bufferlists(&dirty_card_queue_set());
5875 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5876 }
5877 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5878 }
5879
5880 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5881 size_t* pre_used,
5882 FreeRegionList* free_list,
5883 OldRegionSet* old_proxy_set,
5884 HumongousRegionSet* humongous_proxy_set,
5885 HRRSCleanupTask* hrrs_cleanup_task,
5886 bool par) {
5887 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5888 if (hr->isHumongous()) {
5889 assert(hr->startsHumongous(), "we should only see starts humongous");
5890 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5891 } else {
5892 _old_set.remove_with_proxy(hr, old_proxy_set);
5893 free_region(hr, pre_used, free_list, par);
5894 }
5895 } else {
5896 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5897 }
5898 }
5899
5900 void G1CollectedHeap::free_region(HeapRegion* hr,
5901 size_t* pre_used,
5902 FreeRegionList* free_list,
5903 bool par) {
5904 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5905 assert(!hr->is_empty(), "the region should not be empty");
5906 assert(free_list != NULL, "pre-condition");
5907
5908 // Clear the card counts for this region.
5909 // Note: we only need to do this if the region is not young
5910 // (since we don't refine cards in young regions).
5911 if (!hr->is_young()) {
5912 _cg1r->hot_card_cache()->reset_card_counts(hr);
5913 }
5914 *pre_used += hr->used();
5915 hr->hr_clear(par, true /* clear_space */);
5916 free_list->add_as_head(hr);
5917 }
5918
5919 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5920 size_t* pre_used,
5921 FreeRegionList* free_list,
5922 HumongousRegionSet* humongous_proxy_set,
5923 bool par) {
5924 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5925 assert(free_list != NULL, "pre-condition");
5926 assert(humongous_proxy_set != NULL, "pre-condition");
5927
5928 size_t hr_used = hr->used();
5929 size_t hr_capacity = hr->capacity();
5930 size_t hr_pre_used = 0;
5931 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5932 // We need to read this before we make the region non-humongous,
5933 // otherwise the information will be gone.
5934 uint last_index = hr->last_hc_index();
5935 hr->set_notHumongous();
5936 free_region(hr, &hr_pre_used, free_list, par);
5937
5938 uint i = hr->hrs_index() + 1;
5939 while (i < last_index) {
5940 HeapRegion* curr_hr = region_at(i);
5941 assert(curr_hr->continuesHumongous(), "invariant");
5942 curr_hr->set_notHumongous();
5943 free_region(curr_hr, &hr_pre_used, free_list, par);
5944 i += 1;
5945 }
5946 assert(hr_pre_used == hr_used,
5947 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5948 "should be the same", hr_pre_used, hr_used));
5949 *pre_used += hr_pre_used;
5950 }
5951
5952 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5953 FreeRegionList* free_list,
5954 OldRegionSet* old_proxy_set,
5955 HumongousRegionSet* humongous_proxy_set,
5956 bool par) {
5957 if (pre_used > 0) {
5958 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5959 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5960 assert(_summary_bytes_used >= pre_used,
5961 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5962 "should be >= pre_used: "SIZE_FORMAT,
5963 _summary_bytes_used, pre_used));
5964 _summary_bytes_used -= pre_used;
5965 }
5966 if (free_list != NULL && !free_list->is_empty()) {
5967 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5968 _free_list.add_as_head(free_list);
5969 }
5970 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5971 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5972 _old_set.update_from_proxy(old_proxy_set);
5973 }
5974 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5975 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5976 _humongous_set.update_from_proxy(humongous_proxy_set);
5977 }
5978 }
5979
5980 class G1ParCleanupCTTask : public AbstractGangTask {
5981 G1SATBCardTableModRefBS* _ct_bs;
5982 G1CollectedHeap* _g1h;
5983 HeapRegion* volatile _su_head;
5984 public:
5985 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5986 G1CollectedHeap* g1h) :
5987 AbstractGangTask("G1 Par Cleanup CT Task"),
5988 _ct_bs(ct_bs), _g1h(g1h) { }
5989
5990 void work(uint worker_id) {
5991 HeapRegion* r;
5992 while (r = _g1h->pop_dirty_cards_region()) {
5993 clear_cards(r);
5994 }
5995 }
5996
5997 void clear_cards(HeapRegion* r) {
5998 // Cards of the survivors should have already been dirtied.
5999 if (!r->is_survivor()) {
6000 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6001 }
6002 }
6003 };
6004
6005 #ifndef PRODUCT
6006 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6007 G1CollectedHeap* _g1h;
6008 G1SATBCardTableModRefBS* _ct_bs;
6009 public:
6010 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6011 : _g1h(g1h), _ct_bs(ct_bs) { }
6012 virtual bool doHeapRegion(HeapRegion* r) {
6013 if (r->is_survivor()) {
6014 _g1h->verify_dirty_region(r);
6015 } else {
6016 _g1h->verify_not_dirty_region(r);
6017 }
6018 return false;
6019 }
6020 };
6021
6022 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6023 // All of the region should be clean.
6024 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6025 MemRegion mr(hr->bottom(), hr->end());
6026 ct_bs->verify_not_dirty_region(mr);
6027 }
6028
6029 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6030 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6031 // dirty allocated blocks as they allocate them. The thread that
6032 // retires each region and replaces it with a new one will do a
6033 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6034 // not dirty that area (one less thing to have to do while holding
6035 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6036 // is dirty.
6037 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6038 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6039 if (hr->is_young()) {
6040 ct_bs->verify_g1_young_region(mr);
6041 } else {
6042 ct_bs->verify_dirty_region(mr);
6043 }
6044 }
6045
6046 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6047 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6048 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6049 verify_dirty_region(hr);
6050 }
6051 }
6052
6053 void G1CollectedHeap::verify_dirty_young_regions() {
6054 verify_dirty_young_list(_young_list->first_region());
6055 }
6056 #endif
6057
6058 void G1CollectedHeap::cleanUpCardTable() {
6059 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6060 double start = os::elapsedTime();
6061
6062 {
6063 // Iterate over the dirty cards region list.
6064 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6065
6066 if (G1CollectedHeap::use_parallel_gc_threads()) {
6067 set_par_threads();
6068 workers()->run_task(&cleanup_task);
6069 set_par_threads(0);
6070 } else {
6071 while (_dirty_cards_region_list) {
6072 HeapRegion* r = _dirty_cards_region_list;
6073 cleanup_task.clear_cards(r);
6074 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6075 if (_dirty_cards_region_list == r) {
6076 // The last region.
6077 _dirty_cards_region_list = NULL;
6078 }
6079 r->set_next_dirty_cards_region(NULL);
6080 }
6081 }
6082 #ifndef PRODUCT
6083 if (G1VerifyCTCleanup || VerifyAfterGC) {
6084 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6085 heap_region_iterate(&cleanup_verifier);
6086 }
6087 #endif
6088 }
6089
6090 double elapsed = os::elapsedTime() - start;
6091 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6092 }
6093
6094 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6095 size_t pre_used = 0;
6096 FreeRegionList local_free_list("Local List for CSet Freeing");
6097
6098 double young_time_ms = 0.0;
6099 double non_young_time_ms = 0.0;
6100
6101 // Since the collection set is a superset of the the young list,
6102 // all we need to do to clear the young list is clear its
6103 // head and length, and unlink any young regions in the code below
6104 _young_list->clear();
6105
6106 G1CollectorPolicy* policy = g1_policy();
6107
6108 double start_sec = os::elapsedTime();
6109 bool non_young = true;
6110
6111 HeapRegion* cur = cs_head;
6112 int age_bound = -1;
6113 size_t rs_lengths = 0;
6114
6115 while (cur != NULL) {
6116 assert(!is_on_master_free_list(cur), "sanity");
6117 if (non_young) {
6118 if (cur->is_young()) {
6119 double end_sec = os::elapsedTime();
6120 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6121 non_young_time_ms += elapsed_ms;
6122
6123 start_sec = os::elapsedTime();
6124 non_young = false;
6125 }
6126 } else {
6127 if (!cur->is_young()) {
6128 double end_sec = os::elapsedTime();
6129 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6130 young_time_ms += elapsed_ms;
6131
6132 start_sec = os::elapsedTime();
6133 non_young = true;
6134 }
6135 }
6136
6137 rs_lengths += cur->rem_set()->occupied();
6138
6139 HeapRegion* next = cur->next_in_collection_set();
6140 assert(cur->in_collection_set(), "bad CS");
6141 cur->set_next_in_collection_set(NULL);
6142 cur->set_in_collection_set(false);
6143
6144 if (cur->is_young()) {
6145 int index = cur->young_index_in_cset();
6146 assert(index != -1, "invariant");
6147 assert((uint) index < policy->young_cset_region_length(), "invariant");
6148 size_t words_survived = _surviving_young_words[index];
6149 cur->record_surv_words_in_group(words_survived);
6150
6151 // At this point the we have 'popped' cur from the collection set
6152 // (linked via next_in_collection_set()) but it is still in the
6153 // young list (linked via next_young_region()). Clear the
6154 // _next_young_region field.
6155 cur->set_next_young_region(NULL);
6156 } else {
6157 int index = cur->young_index_in_cset();
6158 assert(index == -1, "invariant");
6159 }
6160
6161 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6162 (!cur->is_young() && cur->young_index_in_cset() == -1),
6163 "invariant" );
6164
6165 if (!cur->evacuation_failed()) {
6166 MemRegion used_mr = cur->used_region();
6167
6168 // And the region is empty.
6169 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6170 free_region(cur, &pre_used, &local_free_list, false /* par */);
6171 } else {
6172 cur->uninstall_surv_rate_group();
6173 if (cur->is_young()) {
6174 cur->set_young_index_in_cset(-1);
6175 }
6176 cur->set_not_young();
6177 cur->set_evacuation_failed(false);
6178 // The region is now considered to be old.
6179 _old_set.add(cur);
6180 evacuation_info.increment_collectionset_used_after(cur->used());
6181 }
6182 cur = next;
6183 }
6184
6185 evacuation_info.set_regions_freed(local_free_list.length());
6186 policy->record_max_rs_lengths(rs_lengths);
6187 policy->cset_regions_freed();
6188
6189 double end_sec = os::elapsedTime();
6190 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6191
6192 if (non_young) {
6193 non_young_time_ms += elapsed_ms;
6194 } else {
6195 young_time_ms += elapsed_ms;
6196 }
6197
6198 update_sets_after_freeing_regions(pre_used, &local_free_list,
6199 NULL /* old_proxy_set */,
6200 NULL /* humongous_proxy_set */,
6201 false /* par */);
6202 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6203 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6204 }
6205
6206 // This routine is similar to the above but does not record
6207 // any policy statistics or update free lists; we are abandoning
6208 // the current incremental collection set in preparation of a
6209 // full collection. After the full GC we will start to build up
6210 // the incremental collection set again.
6211 // This is only called when we're doing a full collection
6212 // and is immediately followed by the tearing down of the young list.
6213
6214 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6215 HeapRegion* cur = cs_head;
6216
6217 while (cur != NULL) {
6218 HeapRegion* next = cur->next_in_collection_set();
6219 assert(cur->in_collection_set(), "bad CS");
6220 cur->set_next_in_collection_set(NULL);
6221 cur->set_in_collection_set(false);
6222 cur->set_young_index_in_cset(-1);
6223 cur = next;
6224 }
6225 }
6226
6227 void G1CollectedHeap::set_free_regions_coming() {
6228 if (G1ConcRegionFreeingVerbose) {
6229 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6230 "setting free regions coming");
6231 }
6232
6233 assert(!free_regions_coming(), "pre-condition");
6234 _free_regions_coming = true;
6235 }
6236
6237 void G1CollectedHeap::reset_free_regions_coming() {
6238 assert(free_regions_coming(), "pre-condition");
6239
6240 {
6241 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6242 _free_regions_coming = false;
6243 SecondaryFreeList_lock->notify_all();
6244 }
6245
6246 if (G1ConcRegionFreeingVerbose) {
6247 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6248 "reset free regions coming");
6249 }
6250 }
6251
6252 void G1CollectedHeap::wait_while_free_regions_coming() {
6253 // Most of the time we won't have to wait, so let's do a quick test
6254 // first before we take the lock.
6255 if (!free_regions_coming()) {
6256 return;
6257 }
6258
6259 if (G1ConcRegionFreeingVerbose) {
6260 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6261 "waiting for free regions");
6262 }
6263
6264 {
6265 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6266 while (free_regions_coming()) {
6267 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6268 }
6269 }
6270
6271 if (G1ConcRegionFreeingVerbose) {
6272 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6273 "done waiting for free regions");
6274 }
6275 }
6276
6277 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6278 assert(heap_lock_held_for_gc(),
6279 "the heap lock should already be held by or for this thread");
6280 _young_list->push_region(hr);
6281 }
6282
6283 class NoYoungRegionsClosure: public HeapRegionClosure {
6284 private:
6285 bool _success;
6286 public:
6287 NoYoungRegionsClosure() : _success(true) { }
6288 bool doHeapRegion(HeapRegion* r) {
6289 if (r->is_young()) {
6290 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6291 r->bottom(), r->end());
6292 _success = false;
6293 }
6294 return false;
6295 }
6296 bool success() { return _success; }
6297 };
6298
6299 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6300 bool ret = _young_list->check_list_empty(check_sample);
6301
6302 if (check_heap) {
6303 NoYoungRegionsClosure closure;
6304 heap_region_iterate(&closure);
6305 ret = ret && closure.success();
6306 }
6307
6308 return ret;
6309 }
6310
6311 class TearDownRegionSetsClosure : public HeapRegionClosure {
6312 private:
6313 OldRegionSet *_old_set;
6314
6315 public:
6316 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6317
6318 bool doHeapRegion(HeapRegion* r) {
6319 if (r->is_empty()) {
6320 // We ignore empty regions, we'll empty the free list afterwards
6321 } else if (r->is_young()) {
6322 // We ignore young regions, we'll empty the young list afterwards
6323 } else if (r->isHumongous()) {
6324 // We ignore humongous regions, we're not tearing down the
6325 // humongous region set
6326 } else {
6327 // The rest should be old
6328 _old_set->remove(r);
6329 }
6330 return false;
6331 }
6332
6333 ~TearDownRegionSetsClosure() {
6334 assert(_old_set->is_empty(), "post-condition");
6335 }
6336 };
6337
6338 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6339 assert_at_safepoint(true /* should_be_vm_thread */);
6340
6341 if (!free_list_only) {
6342 TearDownRegionSetsClosure cl(&_old_set);
6343 heap_region_iterate(&cl);
6344
6345 // Need to do this after the heap iteration to be able to
6346 // recognize the young regions and ignore them during the iteration.
6347 _young_list->empty_list();
6348 }
6349 _free_list.remove_all();
6350 }
6351
6352 class RebuildRegionSetsClosure : public HeapRegionClosure {
6353 private:
6354 bool _free_list_only;
6355 OldRegionSet* _old_set;
6356 FreeRegionList* _free_list;
6357 size_t _total_used;
6358
6359 public:
6360 RebuildRegionSetsClosure(bool free_list_only,
6361 OldRegionSet* old_set, FreeRegionList* free_list) :
6362 _free_list_only(free_list_only),
6363 _old_set(old_set), _free_list(free_list), _total_used(0) {
6364 assert(_free_list->is_empty(), "pre-condition");
6365 if (!free_list_only) {
6366 assert(_old_set->is_empty(), "pre-condition");
6367 }
6368 }
6369
6370 bool doHeapRegion(HeapRegion* r) {
6371 if (r->continuesHumongous()) {
6372 return false;
6373 }
6374
6375 if (r->is_empty()) {
6376 // Add free regions to the free list
6377 _free_list->add_as_tail(r);
6378 } else if (!_free_list_only) {
6379 assert(!r->is_young(), "we should not come across young regions");
6380
6381 if (r->isHumongous()) {
6382 // We ignore humongous regions, we left the humongous set unchanged
6383 } else {
6384 // The rest should be old, add them to the old set
6385 _old_set->add(r);
6386 }
6387 _total_used += r->used();
6388 }
6389
6390 return false;
6391 }
6392
6393 size_t total_used() {
6394 return _total_used;
6395 }
6396 };
6397
6398 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6399 assert_at_safepoint(true /* should_be_vm_thread */);
6400
6401 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6402 heap_region_iterate(&cl);
6403
6404 if (!free_list_only) {
6405 _summary_bytes_used = cl.total_used();
6406 }
6407 assert(_summary_bytes_used == recalculate_used(),
6408 err_msg("inconsistent _summary_bytes_used, "
6409 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6410 _summary_bytes_used, recalculate_used()));
6411 }
6412
6413 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6414 _refine_cte_cl->set_concurrent(concurrent);
6415 }
6416
6417 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6418 HeapRegion* hr = heap_region_containing(p);
6419 if (hr == NULL) {
6420 return false;
6421 } else {
6422 return hr->is_in(p);
6423 }
6424 }
6425
6426 // Methods for the mutator alloc region
6427
6428 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6429 bool force) {
6430 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6431 assert(!force || g1_policy()->can_expand_young_list(),
6432 "if force is true we should be able to expand the young list");
6433 bool young_list_full = g1_policy()->is_young_list_full();
6434 if (force || !young_list_full) {
6435 HeapRegion* new_alloc_region = new_region(word_size,
6436 false /* do_expand */);
6437 if (new_alloc_region != NULL) {
6438 set_region_short_lived_locked(new_alloc_region);
6439 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6440 return new_alloc_region;
6441 }
6442 }
6443 return NULL;
6444 }
6445
6446 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6447 size_t allocated_bytes) {
6448 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6449 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6450
6451 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6452 _summary_bytes_used += allocated_bytes;
6453 _hr_printer.retire(alloc_region);
6454 // We update the eden sizes here, when the region is retired,
6455 // instead of when it's allocated, since this is the point that its
6456 // used space has been recored in _summary_bytes_used.
6457 g1mm()->update_eden_size();
6458 }
6459
6460 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6461 bool force) {
6462 return _g1h->new_mutator_alloc_region(word_size, force);
6463 }
6464
6465 void G1CollectedHeap::set_par_threads() {
6466 // Don't change the number of workers. Use the value previously set
6467 // in the workgroup.
6468 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6469 uint n_workers = workers()->active_workers();
6470 assert(UseDynamicNumberOfGCThreads ||
6471 n_workers == workers()->total_workers(),
6472 "Otherwise should be using the total number of workers");
6473 if (n_workers == 0) {
6474 assert(false, "Should have been set in prior evacuation pause.");
6475 n_workers = ParallelGCThreads;
6476 workers()->set_active_workers(n_workers);
6477 }
6478 set_par_threads(n_workers);
6479 }
6480
6481 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6482 size_t allocated_bytes) {
6483 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6484 }
6485
6486 // Methods for the GC alloc regions
6487
6488 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6489 uint count,
6490 GCAllocPurpose ap) {
6491 assert(FreeList_lock->owned_by_self(), "pre-condition");
6492
6493 if (count < g1_policy()->max_regions(ap)) {
6494 HeapRegion* new_alloc_region = new_region(word_size,
6495 true /* do_expand */);
6496 if (new_alloc_region != NULL) {
6497 // We really only need to do this for old regions given that we
6498 // should never scan survivors. But it doesn't hurt to do it
6499 // for survivors too.
6500 new_alloc_region->set_saved_mark();
6501 if (ap == GCAllocForSurvived) {
6502 new_alloc_region->set_survivor();
6503 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6504 } else {
6505 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6506 }
6507 bool during_im = g1_policy()->during_initial_mark_pause();
6508 new_alloc_region->note_start_of_copying(during_im);
6509 return new_alloc_region;
6510 } else {
6511 g1_policy()->note_alloc_region_limit_reached(ap);
6512 }
6513 }
6514 return NULL;
6515 }
6516
6517 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6518 size_t allocated_bytes,
6519 GCAllocPurpose ap) {
6520 bool during_im = g1_policy()->during_initial_mark_pause();
6521 alloc_region->note_end_of_copying(during_im);
6522 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6523 if (ap == GCAllocForSurvived) {
6524 young_list()->add_survivor_region(alloc_region);
6525 } else {
6526 _old_set.add(alloc_region);
6527 }
6528 _hr_printer.retire(alloc_region);
6529 }
6530
6531 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6532 bool force) {
6533 assert(!force, "not supported for GC alloc regions");
6534 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6535 }
6536
6537 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6538 size_t allocated_bytes) {
6539 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6540 GCAllocForSurvived);
6541 }
6542
6543 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6544 bool force) {
6545 assert(!force, "not supported for GC alloc regions");
6546 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6547 }
6548
6549 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6550 size_t allocated_bytes) {
6551 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6552 GCAllocForTenured);
6553 }
6554 // Heap region set verification
6555
6556 class VerifyRegionListsClosure : public HeapRegionClosure {
6557 private:
6558 FreeRegionList* _free_list;
6559 OldRegionSet* _old_set;
6560 HumongousRegionSet* _humongous_set;
6561 uint _region_count;
6562
6563 public:
6564 VerifyRegionListsClosure(OldRegionSet* old_set,
6565 HumongousRegionSet* humongous_set,
6566 FreeRegionList* free_list) :
6567 _old_set(old_set), _humongous_set(humongous_set),
6568 _free_list(free_list), _region_count(0) { }
6569
6570 uint region_count() { return _region_count; }
6571
6572 bool doHeapRegion(HeapRegion* hr) {
6573 _region_count += 1;
6574
6575 if (hr->continuesHumongous()) {
6576 return false;
6577 }
6578
6579 if (hr->is_young()) {
6580 // TODO
6581 } else if (hr->startsHumongous()) {
6582 _humongous_set->verify_next_region(hr);
6583 } else if (hr->is_empty()) {
6584 _free_list->verify_next_region(hr);
6585 } else {
6586 _old_set->verify_next_region(hr);
6587 }
6588 return false;
6589 }
6590 };
6591
6592 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6593 HeapWord* bottom) {
6594 HeapWord* end = bottom + HeapRegion::GrainWords;
6595 MemRegion mr(bottom, end);
6596 assert(_g1_reserved.contains(mr), "invariant");
6597 // This might return NULL if the allocation fails
6598 return new HeapRegion(hrs_index, _bot_shared, mr);
6599 }
6600
6601 void G1CollectedHeap::verify_region_sets() {
6602 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6603
6604 // First, check the explicit lists.
6605 _free_list.verify();
6606 {
6607 // Given that a concurrent operation might be adding regions to
6608 // the secondary free list we have to take the lock before
6609 // verifying it.
6610 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6611 _secondary_free_list.verify();
6612 }
6613 _old_set.verify();
6614 _humongous_set.verify();
6615
6616 // If a concurrent region freeing operation is in progress it will
6617 // be difficult to correctly attributed any free regions we come
6618 // across to the correct free list given that they might belong to
6619 // one of several (free_list, secondary_free_list, any local lists,
6620 // etc.). So, if that's the case we will skip the rest of the
6621 // verification operation. Alternatively, waiting for the concurrent
6622 // operation to complete will have a non-trivial effect on the GC's
6623 // operation (no concurrent operation will last longer than the
6624 // interval between two calls to verification) and it might hide
6625 // any issues that we would like to catch during testing.
6626 if (free_regions_coming()) {
6627 return;
6628 }
6629
6630 // Make sure we append the secondary_free_list on the free_list so
6631 // that all free regions we will come across can be safely
6632 // attributed to the free_list.
6633 append_secondary_free_list_if_not_empty_with_lock();
6634
6635 // Finally, make sure that the region accounting in the lists is
6636 // consistent with what we see in the heap.
6637 _old_set.verify_start();
6638 _humongous_set.verify_start();
6639 _free_list.verify_start();
6640
6641 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6642 heap_region_iterate(&cl);
6643
6644 _old_set.verify_end();
6645 _humongous_set.verify_end();
6646 _free_list.verify_end();
6647 }
6648
6649 // Optimized nmethod scanning
6650
6651 class RegisterNMethodOopClosure: public OopClosure {
6652 G1CollectedHeap* _g1h;
6653 nmethod* _nm;
6654
6655 template <class T> void do_oop_work(T* p) {
6656 T heap_oop = oopDesc::load_heap_oop(p);
6657 if (!oopDesc::is_null(heap_oop)) {
6658 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6659 HeapRegion* hr = _g1h->heap_region_containing(obj);
6660 assert(!hr->continuesHumongous(),
6661 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6662 " starting at "HR_FORMAT,
6663 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6664
6665 // HeapRegion::add_strong_code_root() avoids adding duplicate
6666 // entries but having duplicates is OK since we "mark" nmethods
6667 // as visited when we scan the strong code root lists during the GC.
6668 hr->add_strong_code_root(_nm);
6669 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6670 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6671 _nm, HR_FORMAT_PARAMS(hr)));
6672 }
6673 }
6674
6675 public:
6676 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6677 _g1h(g1h), _nm(nm) {}
6678
6679 void do_oop(oop* p) { do_oop_work(p); }
6680 void do_oop(narrowOop* p) { do_oop_work(p); }
6681 };
6682
6683 class UnregisterNMethodOopClosure: public OopClosure {
6684 G1CollectedHeap* _g1h;
6685 nmethod* _nm;
6686
6687 template <class T> void do_oop_work(T* p) {
6688 T heap_oop = oopDesc::load_heap_oop(p);
6689 if (!oopDesc::is_null(heap_oop)) {
6690 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6691 HeapRegion* hr = _g1h->heap_region_containing(obj);
6692 assert(!hr->continuesHumongous(),
6693 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6694 " starting at "HR_FORMAT,
6695 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6696
6697 hr->remove_strong_code_root(_nm);
6698 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6699 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6700 _nm, HR_FORMAT_PARAMS(hr)));
6701 }
6702 }
6703
6704 public:
6705 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6706 _g1h(g1h), _nm(nm) {}
6707
6708 void do_oop(oop* p) { do_oop_work(p); }
6709 void do_oop(narrowOop* p) { do_oop_work(p); }
6710 };
6711
6712 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6713 CollectedHeap::register_nmethod(nm);
6714
6715 guarantee(nm != NULL, "sanity");
6716 RegisterNMethodOopClosure reg_cl(this, nm);
6717 nm->oops_do(®_cl);
6718 }
6719
6720 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6721 CollectedHeap::unregister_nmethod(nm);
6722
6723 guarantee(nm != NULL, "sanity");
6724 UnregisterNMethodOopClosure reg_cl(this, nm);
6725 nm->oops_do(®_cl, true);
6726 }
6727
6728 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6729 public:
6730 bool doHeapRegion(HeapRegion *hr) {
6731 assert(!hr->isHumongous(),
6732 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6733 HR_FORMAT_PARAMS(hr)));
6734 hr->migrate_strong_code_roots();
6735 return false;
6736 }
6737 };
6738
6739 void G1CollectedHeap::migrate_strong_code_roots() {
6740 MigrateCodeRootsHeapRegionClosure cl;
6741 double migrate_start = os::elapsedTime();
6742 collection_set_iterate(&cl);
6743 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6744 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6745 }
6746
6747 // Mark all the code roots that point into regions *not* in the
6748 // collection set.
6749 //
6750 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6751 // walking the the code roots lists of regions not in the collection
6752 // set. Suppose we have an nmethod (M) that points to objects in two
6753 // separate regions - one in the collection set (R1) and one not (R2).
6754 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6755 // nmethod M when walking the code roots for R1. When we come to scan
6756 // the code roots for R2, we would see that M is already marked and it
6757 // would be skipped and the objects in R2 that are referenced from M
6758 // would not be evacuated.
6759
6760 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6761
6762 class MarkStrongCodeRootOopClosure: public OopClosure {
6763 ConcurrentMark* _cm;
6764 HeapRegion* _hr;
6765 uint _worker_id;
6766
6767 template <class T> void do_oop_work(T* p) {
6768 T heap_oop = oopDesc::load_heap_oop(p);
6769 if (!oopDesc::is_null(heap_oop)) {
6770 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6771 // Only mark objects in the region (which is assumed
6772 // to be not in the collection set).
6773 if (_hr->is_in(obj)) {
6774 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6775 }
6776 }
6777 }
6778
6779 public:
6780 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6781 _cm(cm), _hr(hr), _worker_id(worker_id) {
6782 assert(!_hr->in_collection_set(), "sanity");
6783 }
6784
6785 void do_oop(narrowOop* p) { do_oop_work(p); }
6786 void do_oop(oop* p) { do_oop_work(p); }
6787 };
6788
6789 MarkStrongCodeRootOopClosure _oop_cl;
6790
6791 public:
6792 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6793 _oop_cl(cm, hr, worker_id) {}
6794
6795 void do_code_blob(CodeBlob* cb) {
6796 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6797 if (nm != NULL) {
6798 nm->oops_do(&_oop_cl);
6799 }
6800 }
6801 };
6802
6803 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6804 G1CollectedHeap* _g1h;
6805 uint _worker_id;
6806
6807 public:
6808 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6809 _g1h(g1h), _worker_id(worker_id) {}
6810
6811 bool doHeapRegion(HeapRegion *hr) {
6812 HeapRegionRemSet* hrrs = hr->rem_set();
6813 if (hr->continuesHumongous()) {
6814 // Code roots should never be attached to a continuation of a humongous region
6815 assert(hrrs->strong_code_roots_list_length() == 0,
6816 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6817 " starting at "HR_FORMAT", but has "INT32_FORMAT,
6818 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6819 hrrs->strong_code_roots_list_length()));
6820 return false;
6821 }
6822
6823 if (hr->in_collection_set()) {
6824 // Don't mark code roots into regions in the collection set here.
6825 // They will be marked when we scan them.
6826 return false;
6827 }
6828
6829 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6830 hr->strong_code_roots_do(&cb_cl);
6831 return false;
6832 }
6833 };
6834
6835 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6836 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6837 if (G1CollectedHeap::use_parallel_gc_threads()) {
6838 heap_region_par_iterate_chunked(&cl,
6839 worker_id,
6840 workers()->active_workers(),
6841 HeapRegion::ParMarkRootClaimValue);
6842 } else {
6843 heap_region_iterate(&cl);
6844 }
6845 }
6846
6847 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6848 G1CollectedHeap* _g1h;
6849
6850 public:
6851 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6852 _g1h(g1h) {}
6853
6854 void do_code_blob(CodeBlob* cb) {
6855 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6856 if (nm == NULL) {
6857 return;
6858 }
6859
6860 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6861 _g1h->register_nmethod(nm);
6862 }
6863 }
6864 };
6865
6866 void G1CollectedHeap::rebuild_strong_code_roots() {
6867 RebuildStrongCodeRootClosure blob_cl(this);
6868 CodeCache::blobs_do(&blob_cl);
6869 }