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/heapRegion.inline.hpp"
43 #include "gc_implementation/g1/heapRegionRemSet.hpp"
44 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
45 #include "gc_implementation/g1/vm_operations_g1.hpp"
46 #include "gc_implementation/shared/isGCActiveMark.hpp"
47 #include "memory/gcLocker.inline.hpp"
48 #include "memory/genOopClosures.inline.hpp"
49 #include "memory/generationSpec.hpp"
50 #include "memory/referenceProcessor.hpp"
51 #include "oops/oop.inline.hpp"
52 #include "oops/oop.pcgc.inline.hpp"
53 #include "runtime/aprofiler.hpp"
54 #include "runtime/vmThread.hpp"
55
56 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
57
58 // turn it on so that the contents of the young list (scan-only /
59 // to-be-collected) are printed at "strategic" points before / during
60 // / after the collection --- this is useful for debugging
61 #define YOUNG_LIST_VERBOSE 0
62 // CURRENT STATUS
63 // This file is under construction. Search for "FIXME".
64
65 // INVARIANTS/NOTES
66 //
67 // All allocation activity covered by the G1CollectedHeap interface is
68 // serialized by acquiring the HeapLock. This happens in mem_allocate
69 // and allocate_new_tlab, which are the "entry" points to the
70 // allocation code from the rest of the JVM. (Note that this does not
71 // apply to TLAB allocation, which is not part of this interface: it
72 // is done by clients of this interface.)
73
74 // Notes on implementation of parallelism in different tasks.
75 //
76 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
77 // The number of GC workers is passed to heap_region_par_iterate_chunked().
78 // It does use run_task() which sets _n_workers in the task.
79 // G1ParTask executes g1_process_strong_roots() ->
80 // SharedHeap::process_strong_roots() which calls eventuall to
81 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
82 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
83 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
84 //
85
86 // Local to this file.
87
88 class RefineCardTableEntryClosure: public CardTableEntryClosure {
89 SuspendibleThreadSet* _sts;
90 G1RemSet* _g1rs;
91 ConcurrentG1Refine* _cg1r;
92 bool _concurrent;
93 public:
94 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
95 G1RemSet* g1rs,
96 ConcurrentG1Refine* cg1r) :
97 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
98 {}
99 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
100 bool oops_into_cset = _g1rs->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && _sts->should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113 void set_concurrent(bool b) { _concurrent = b; }
114 };
115
116
117 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
118 int _calls;
119 G1CollectedHeap* _g1h;
120 CardTableModRefBS* _ctbs;
121 int _histo[256];
122 public:
123 ClearLoggedCardTableEntryClosure() :
124 _calls(0)
125 {
126 _g1h = G1CollectedHeap::heap();
127 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
128 for (int i = 0; i < 256; i++) _histo[i] = 0;
129 }
130 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
131 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
132 _calls++;
133 unsigned char* ujb = (unsigned char*)card_ptr;
134 int ind = (int)(*ujb);
135 _histo[ind]++;
136 *card_ptr = -1;
137 }
138 return true;
139 }
140 int calls() { return _calls; }
141 void print_histo() {
142 gclog_or_tty->print_cr("Card table value histogram:");
143 for (int i = 0; i < 256; i++) {
144 if (_histo[i] != 0) {
145 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
146 }
147 }
148 }
149 };
150
151 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
152 int _calls;
153 G1CollectedHeap* _g1h;
154 CardTableModRefBS* _ctbs;
155 public:
156 RedirtyLoggedCardTableEntryClosure() :
157 _calls(0)
158 {
159 _g1h = G1CollectedHeap::heap();
160 _ctbs = (CardTableModRefBS*)_g1h->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 collecction.
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 = (CardTableModRefBS*)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 notifed 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 expasion 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 seriers.
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 satisified, 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 if (result != NULL) {
982 assert(succeeded, "only way to get back a non-NULL result");
983 return result;
984 }
985
986 if (succeeded) {
987 // If we get here we successfully scheduled a collection which
988 // failed to allocate. No point in trying to allocate
989 // further. We'll just return NULL.
990 MutexLockerEx x(Heap_lock);
991 *gc_count_before_ret = total_collections();
992 return NULL;
993 }
994 } else {
995 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
996 MutexLockerEx x(Heap_lock);
997 *gc_count_before_ret = total_collections();
998 return NULL;
999 }
1000 // The GCLocker is either active or the GCLocker initiated
1001 // GC has not yet been performed. Stall until it is and
1002 // then retry the allocation.
1003 GC_locker::stall_until_clear();
1004 (*gclocker_retry_count_ret) += 1;
1005 }
1006
1007 // We can reach here if we were unsuccessul in scheduling a
1008 // collection (because another thread beat us to it) or if we were
1009 // stalled due to the GC locker. In either can we should retry the
1010 // allocation attempt in case another thread successfully
1011 // performed a collection and reclaimed enough space. We do the
1012 // first attempt (without holding the Heap_lock) here and the
1013 // follow-on attempt will be at the start of the next loop
1014 // iteration (after taking the Heap_lock).
1015 result = _mutator_alloc_region.attempt_allocation(word_size,
1016 false /* bot_updates */);
1017 if (result != NULL) {
1018 return result;
1019 }
1020
1021 // Give a warning if we seem to be looping forever.
1022 if ((QueuedAllocationWarningCount > 0) &&
1023 (try_count % QueuedAllocationWarningCount == 0)) {
1024 warning("G1CollectedHeap::attempt_allocation_slow() "
1025 "retries %d times", try_count);
1026 }
1027 }
1028
1029 ShouldNotReachHere();
1030 return NULL;
1031 }
1032
1033 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1034 unsigned int * gc_count_before_ret,
1035 int* gclocker_retry_count_ret) {
1036 // The structure of this method has a lot of similarities to
1037 // attempt_allocation_slow(). The reason these two were not merged
1038 // into a single one is that such a method would require several "if
1039 // allocation is not humongous do this, otherwise do that"
1040 // conditional paths which would obscure its flow. In fact, an early
1041 // version of this code did use a unified method which was harder to
1042 // follow and, as a result, it had subtle bugs that were hard to
1043 // track down. So keeping these two methods separate allows each to
1044 // be more readable. It will be good to keep these two in sync as
1045 // much as possible.
1046
1047 assert_heap_not_locked_and_not_at_safepoint();
1048 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1049 "should only be called for humongous allocations");
1050
1051 // Humongous objects can exhaust the heap quickly, so we should check if we
1052 // need to start a marking cycle at each humongous object allocation. We do
1053 // the check before we do the actual allocation. The reason for doing it
1054 // before the allocation is that we avoid having to keep track of the newly
1055 // allocated memory while we do a GC.
1056 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1057 word_size)) {
1058 collect(GCCause::_g1_humongous_allocation);
1059 }
1060
1061 // We will loop until a) we manage to successfully perform the
1062 // allocation or b) we successfully schedule a collection which
1063 // fails to perform the allocation. b) is the only case when we'll
1064 // return NULL.
1065 HeapWord* result = NULL;
1066 for (int try_count = 1; /* we'll return */; try_count += 1) {
1067 bool should_try_gc;
1068 unsigned int gc_count_before;
1069
1070 {
1071 MutexLockerEx x(Heap_lock);
1072
1073 // Given that humongous objects are not allocated in young
1074 // regions, we'll first try to do the allocation without doing a
1075 // collection hoping that there's enough space in the heap.
1076 result = humongous_obj_allocate(word_size);
1077 if (result != NULL) {
1078 return result;
1079 }
1080
1081 if (GC_locker::is_active_and_needs_gc()) {
1082 should_try_gc = false;
1083 } else {
1084 // The GCLocker may not be active but the GCLocker initiated
1085 // GC may not yet have been performed (GCLocker::needs_gc()
1086 // returns true). In this case we do not try this GC and
1087 // wait until the GCLocker initiated GC is performed, and
1088 // then retry the allocation.
1089 if (GC_locker::needs_gc()) {
1090 should_try_gc = false;
1091 } else {
1092 // Read the GC count while still holding the Heap_lock.
1093 gc_count_before = total_collections();
1094 should_try_gc = true;
1095 }
1096 }
1097 }
1098
1099 if (should_try_gc) {
1100 // If we failed to allocate the humongous object, we should try to
1101 // do a collection pause (if we're allowed) in case it reclaims
1102 // enough space for the allocation to succeed after the pause.
1103
1104 bool succeeded;
1105 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1106 if (result != NULL) {
1107 assert(succeeded, "only way to get back a non-NULL result");
1108 return result;
1109 }
1110
1111 if (succeeded) {
1112 // If we get here we successfully scheduled a collection which
1113 // failed to allocate. No point in trying to allocate
1114 // further. We'll just return NULL.
1115 MutexLockerEx x(Heap_lock);
1116 *gc_count_before_ret = total_collections();
1117 return NULL;
1118 }
1119 } else {
1120 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1121 MutexLockerEx x(Heap_lock);
1122 *gc_count_before_ret = total_collections();
1123 return NULL;
1124 }
1125 // The GCLocker is either active or the GCLocker initiated
1126 // GC has not yet been performed. Stall until it is and
1127 // then retry the allocation.
1128 GC_locker::stall_until_clear();
1129 (*gclocker_retry_count_ret) += 1;
1130 }
1131
1132 // We can reach here if we were unsuccessul in scheduling a
1133 // collection (because another thread beat us to it) or if we were
1134 // stalled due to the GC locker. In either can we should retry the
1135 // allocation attempt in case another thread successfully
1136 // performed a collection and reclaimed enough space. Give a
1137 // warning if we seem to be looping forever.
1138
1139 if ((QueuedAllocationWarningCount > 0) &&
1140 (try_count % QueuedAllocationWarningCount == 0)) {
1141 warning("G1CollectedHeap::attempt_allocation_humongous() "
1142 "retries %d times", try_count);
1143 }
1144 }
1145
1146 ShouldNotReachHere();
1147 return NULL;
1148 }
1149
1150 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1151 bool expect_null_mutator_alloc_region) {
1152 assert_at_safepoint(true /* should_be_vm_thread */);
1153 assert(_mutator_alloc_region.get() == NULL ||
1154 !expect_null_mutator_alloc_region,
1155 "the current alloc region was unexpectedly found to be non-NULL");
1156
1157 if (!isHumongous(word_size)) {
1158 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1159 false /* bot_updates */);
1160 } else {
1161 HeapWord* result = humongous_obj_allocate(word_size);
1162 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1163 g1_policy()->set_initiate_conc_mark_if_possible();
1164 }
1165 return result;
1166 }
1167
1168 ShouldNotReachHere();
1169 }
1170
1171 class PostMCRemSetClearClosure: public HeapRegionClosure {
1172 G1CollectedHeap* _g1h;
1173 ModRefBarrierSet* _mr_bs;
1174 public:
1175 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1176 _g1h(g1h), _mr_bs(mr_bs) {}
1177
1178 bool doHeapRegion(HeapRegion* r) {
1179 HeapRegionRemSet* hrrs = r->rem_set();
1180
1181 if (r->continuesHumongous()) {
1182 // We'll assert that the strong code root list is empty
1183 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1184 return false;
1185 }
1186
1187 _g1h->reset_gc_time_stamps(r);
1188 hrrs->clear();
1189 // You might think here that we could clear just the cards
1190 // corresponding to the used region. But no: if we leave a dirty card
1191 // in a region we might allocate into, then it would prevent that card
1192 // from being enqueued, and cause it to be missed.
1193 // Re: the performance cost: we shouldn't be doing full GC anyway!
1194 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1195
1196 return false;
1197 }
1198 };
1199
1200 void G1CollectedHeap::clear_rsets_post_compaction() {
1201 PostMCRemSetClearClosure rs_clear(this, mr_bs());
1202 heap_region_iterate(&rs_clear);
1203 }
1204
1205 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1206 G1CollectedHeap* _g1h;
1207 UpdateRSOopClosure _cl;
1208 int _worker_i;
1209 public:
1210 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1211 _cl(g1->g1_rem_set(), worker_i),
1212 _worker_i(worker_i),
1213 _g1h(g1)
1214 { }
1215
1216 bool doHeapRegion(HeapRegion* r) {
1217 if (!r->continuesHumongous()) {
1218 _cl.set_from(r);
1219 r->oop_iterate(&_cl);
1220 }
1221 return false;
1222 }
1223 };
1224
1225 class ParRebuildRSTask: public AbstractGangTask {
1226 G1CollectedHeap* _g1;
1227 public:
1228 ParRebuildRSTask(G1CollectedHeap* g1)
1229 : AbstractGangTask("ParRebuildRSTask"),
1230 _g1(g1)
1231 { }
1232
1233 void work(uint worker_id) {
1234 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1235 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1236 _g1->workers()->active_workers(),
1237 HeapRegion::RebuildRSClaimValue);
1238 }
1239 };
1240
1241 class PostCompactionPrinterClosure: public HeapRegionClosure {
1242 private:
1243 G1HRPrinter* _hr_printer;
1244 public:
1245 bool doHeapRegion(HeapRegion* hr) {
1246 assert(!hr->is_young(), "not expecting to find young regions");
1247 // We only generate output for non-empty regions.
1248 if (!hr->is_empty()) {
1249 if (!hr->isHumongous()) {
1250 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1251 } else if (hr->startsHumongous()) {
1252 if (hr->region_num() == 1) {
1253 // single humongous region
1254 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1255 } else {
1256 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1257 }
1258 } else {
1259 assert(hr->continuesHumongous(), "only way to get here");
1260 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1261 }
1262 }
1263 return false;
1264 }
1265
1266 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1267 : _hr_printer(hr_printer) { }
1268 };
1269
1270 void G1CollectedHeap::print_hrs_post_compaction() {
1271 PostCompactionPrinterClosure cl(hr_printer());
1272 heap_region_iterate(&cl);
1273 }
1274
1275 bool G1CollectedHeap::do_collection(bool explicit_gc,
1276 bool clear_all_soft_refs,
1277 size_t word_size) {
1278 assert_at_safepoint(true /* should_be_vm_thread */);
1279
1280 if (GC_locker::check_active_before_gc()) {
1281 return false;
1282 }
1283
1284 SvcGCMarker sgcm(SvcGCMarker::FULL);
1285 ResourceMark rm;
1286
1287 print_heap_before_gc();
1288
1289 size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
1290
1291 HRSPhaseSetter x(HRSPhaseFullGC);
1292 verify_region_sets_optional();
1293
1294 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1295 collector_policy()->should_clear_all_soft_refs();
1296
1297 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1298
1299 {
1300 IsGCActiveMark x;
1301
1302 // Timing
1303 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1304 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1305 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1306
1307 {
1308 TraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, gclog_or_tty);
1309 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1310 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1311
1312 double start = os::elapsedTime();
1313 g1_policy()->record_full_collection_start();
1314
1315 // Note: When we have a more flexible GC logging framework that
1316 // allows us to add optional attributes to a GC log record we
1317 // could consider timing and reporting how long we wait in the
1318 // following two methods.
1319 wait_while_free_regions_coming();
1320 // If we start the compaction before the CM threads finish
1321 // scanning the root regions we might trip them over as we'll
1322 // be moving objects / updating references. So let's wait until
1323 // they are done. By telling them to abort, they should complete
1324 // early.
1325 _cm->root_regions()->abort();
1326 _cm->root_regions()->wait_until_scan_finished();
1327 append_secondary_free_list_if_not_empty_with_lock();
1328
1329 gc_prologue(true);
1330 increment_total_collections(true /* full gc */);
1331 increment_old_marking_cycles_started();
1332
1333 assert(used() == recalculate_used(), "Should be equal");
1334
1335 verify_before_gc();
1336
1337 pre_full_gc_dump();
1338
1339 COMPILER2_PRESENT(DerivedPointerTable::clear());
1340
1341 // Disable discovery and empty the discovered lists
1342 // for the CM ref processor.
1343 ref_processor_cm()->disable_discovery();
1344 ref_processor_cm()->abandon_partial_discovery();
1345 ref_processor_cm()->verify_no_references_recorded();
1346
1347 // Abandon current iterations of concurrent marking and concurrent
1348 // refinement, if any are in progress. We have to do this before
1349 // wait_until_scan_finished() below.
1350 concurrent_mark()->abort();
1351
1352 // Make sure we'll choose a new allocation region afterwards.
1353 release_mutator_alloc_region();
1354 abandon_gc_alloc_regions();
1355 g1_rem_set()->cleanupHRRS();
1356
1357 // We should call this after we retire any currently active alloc
1358 // regions so that all the ALLOC / RETIRE events are generated
1359 // before the start GC event.
1360 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1361
1362 // We may have added regions to the current incremental collection
1363 // set between the last GC or pause and now. We need to clear the
1364 // incremental collection set and then start rebuilding it afresh
1365 // after this full GC.
1366 abandon_collection_set(g1_policy()->inc_cset_head());
1367 g1_policy()->clear_incremental_cset();
1368 g1_policy()->stop_incremental_cset_building();
1369
1370 tear_down_region_sets(false /* free_list_only */);
1371 g1_policy()->set_gcs_are_young(true);
1372
1373 // See the comments in g1CollectedHeap.hpp and
1374 // G1CollectedHeap::ref_processing_init() about
1375 // how reference processing currently works in G1.
1376
1377 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1378 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1379
1380 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1381 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1382
1383 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1384 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1385
1386 // Do collection work
1387 {
1388 HandleMark hm; // Discard invalid handles created during gc
1389 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1390 }
1391
1392 assert(free_regions() == 0, "we should not have added any free regions");
1393 rebuild_region_sets(false /* free_list_only */);
1394
1395 // Enqueue any discovered reference objects that have
1396 // not been removed from the discovered lists.
1397 ref_processor_stw()->enqueue_discovered_references();
1398
1399 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1400
1401 MemoryService::track_memory_usage();
1402
1403 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1404 ref_processor_stw()->verify_no_references_recorded();
1405
1406 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1407 ClassLoaderDataGraph::purge();
1408 MetaspaceAux::verify_metrics();
1409
1410 // Note: since we've just done a full GC, concurrent
1411 // marking is no longer active. Therefore we need not
1412 // re-enable reference discovery for the CM ref processor.
1413 // That will be done at the start of the next marking cycle.
1414 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1415 ref_processor_cm()->verify_no_references_recorded();
1416
1417 reset_gc_time_stamp();
1418 // Since everything potentially moved, we will clear all remembered
1419 // sets, and clear all cards. Later we will rebuild remebered
1420 // sets. We will also reset the GC time stamps of the regions.
1421 clear_rsets_post_compaction();
1422 check_gc_time_stamps();
1423
1424 // Resize the heap if necessary.
1425 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1426
1427 if (_hr_printer.is_active()) {
1428 // We should do this after we potentially resize the heap so
1429 // that all the COMMIT / UNCOMMIT events are generated before
1430 // the end GC event.
1431
1432 print_hrs_post_compaction();
1433 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1434 }
1435
1436 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1437 if (hot_card_cache->use_cache()) {
1438 hot_card_cache->reset_card_counts();
1439 hot_card_cache->reset_hot_cache();
1440 }
1441
1442 // Rebuild remembered sets of all regions.
1443 if (G1CollectedHeap::use_parallel_gc_threads()) {
1444 uint n_workers =
1445 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1446 workers()->active_workers(),
1447 Threads::number_of_non_daemon_threads());
1448 assert(UseDynamicNumberOfGCThreads ||
1449 n_workers == workers()->total_workers(),
1450 "If not dynamic should be using all the workers");
1451 workers()->set_active_workers(n_workers);
1452 // Set parallel threads in the heap (_n_par_threads) only
1453 // before a parallel phase and always reset it to 0 after
1454 // the phase so that the number of parallel threads does
1455 // no get carried forward to a serial phase where there
1456 // may be code that is "possibly_parallel".
1457 set_par_threads(n_workers);
1458
1459 ParRebuildRSTask rebuild_rs_task(this);
1460 assert(check_heap_region_claim_values(
1461 HeapRegion::InitialClaimValue), "sanity check");
1462 assert(UseDynamicNumberOfGCThreads ||
1463 workers()->active_workers() == workers()->total_workers(),
1464 "Unless dynamic should use total workers");
1465 // Use the most recent number of active workers
1466 assert(workers()->active_workers() > 0,
1467 "Active workers not properly set");
1468 set_par_threads(workers()->active_workers());
1469 workers()->run_task(&rebuild_rs_task);
1470 set_par_threads(0);
1471 assert(check_heap_region_claim_values(
1472 HeapRegion::RebuildRSClaimValue), "sanity check");
1473 reset_heap_region_claim_values();
1474 } else {
1475 RebuildRSOutOfRegionClosure rebuild_rs(this);
1476 heap_region_iterate(&rebuild_rs);
1477 }
1478
1479 // Rebuild the strong code root lists for each region
1480 rebuild_strong_code_roots();
1481
1482 if (true) { // FIXME
1483 MetaspaceGC::compute_new_size();
1484 }
1485
1486 #ifdef TRACESPINNING
1487 ParallelTaskTerminator::print_termination_counts();
1488 #endif
1489
1490 // Discard all rset updates
1491 JavaThread::dirty_card_queue_set().abandon_logs();
1492 assert(!G1DeferredRSUpdate
1493 || (G1DeferredRSUpdate &&
1494 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1495
1496 _young_list->reset_sampled_info();
1497 // At this point there should be no regions in the
1498 // entire heap tagged as young.
1499 assert(check_young_list_empty(true /* check_heap */),
1500 "young list should be empty at this point");
1501
1502 // Update the number of full collections that have been completed.
1503 increment_old_marking_cycles_completed(false /* concurrent */);
1504
1505 _hrs.verify_optional();
1506 verify_region_sets_optional();
1507
1508 verify_after_gc();
1509
1510 // Start a new incremental collection set for the next pause
1511 assert(g1_policy()->collection_set() == NULL, "must be");
1512 g1_policy()->start_incremental_cset_building();
1513
1514 // Clear the _cset_fast_test bitmap in anticipation of adding
1515 // regions to the incremental collection set for the next
1516 // evacuation pause.
1517 clear_cset_fast_test();
1518
1519 init_mutator_alloc_region();
1520
1521 double end = os::elapsedTime();
1522 g1_policy()->record_full_collection_end();
1523
1524 if (G1Log::fine()) {
1525 g1_policy()->print_heap_transition();
1526 }
1527
1528 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1529 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1530 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1531 // before any GC notifications are raised.
1532 g1mm()->update_sizes();
1533
1534 gc_epilogue(true);
1535 }
1536
1537 if (G1Log::finer()) {
1538 g1_policy()->print_detailed_heap_transition(true /* full */);
1539 }
1540
1541 print_heap_after_gc();
1542
1543 post_full_gc_dump();
1544 }
1545
1546 return true;
1547 }
1548
1549 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1550 // do_collection() will return whether it succeeded in performing
1551 // the GC. Currently, there is no facility on the
1552 // do_full_collection() API to notify the caller than the collection
1553 // did not succeed (e.g., because it was locked out by the GC
1554 // locker). So, right now, we'll ignore the return value.
1555 bool dummy = do_collection(true, /* explicit_gc */
1556 clear_all_soft_refs,
1557 0 /* word_size */);
1558 }
1559
1560 // This code is mostly copied from TenuredGeneration.
1561 void
1562 G1CollectedHeap::
1563 resize_if_necessary_after_full_collection(size_t word_size) {
1564 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1565
1566 // Include the current allocation, if any, and bytes that will be
1567 // pre-allocated to support collections, as "used".
1568 const size_t used_after_gc = used();
1569 const size_t capacity_after_gc = capacity();
1570 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1571
1572 // This is enforced in arguments.cpp.
1573 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1574 "otherwise the code below doesn't make sense");
1575
1576 // We don't have floating point command-line arguments
1577 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1578 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1579 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1580 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1581
1582 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1583 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1584
1585 // We have to be careful here as these two calculations can overflow
1586 // 32-bit size_t's.
1587 double used_after_gc_d = (double) used_after_gc;
1588 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1589 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1590
1591 // Let's make sure that they are both under the max heap size, which
1592 // by default will make them fit into a size_t.
1593 double desired_capacity_upper_bound = (double) max_heap_size;
1594 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1595 desired_capacity_upper_bound);
1596 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1597 desired_capacity_upper_bound);
1598
1599 // We can now safely turn them into size_t's.
1600 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1601 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1602
1603 // This assert only makes sense here, before we adjust them
1604 // with respect to the min and max heap size.
1605 assert(minimum_desired_capacity <= maximum_desired_capacity,
1606 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1607 "maximum_desired_capacity = "SIZE_FORMAT,
1608 minimum_desired_capacity, maximum_desired_capacity));
1609
1610 // Should not be greater than the heap max size. No need to adjust
1611 // it with respect to the heap min size as it's a lower bound (i.e.,
1612 // we'll try to make the capacity larger than it, not smaller).
1613 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1614 // Should not be less than the heap min size. No need to adjust it
1615 // with respect to the heap max size as it's an upper bound (i.e.,
1616 // we'll try to make the capacity smaller than it, not greater).
1617 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1618
1619 if (capacity_after_gc < minimum_desired_capacity) {
1620 // Don't expand unless it's significant
1621 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1622 ergo_verbose4(ErgoHeapSizing,
1623 "attempt heap expansion",
1624 ergo_format_reason("capacity lower than "
1625 "min desired capacity after Full GC")
1626 ergo_format_byte("capacity")
1627 ergo_format_byte("occupancy")
1628 ergo_format_byte_perc("min desired capacity"),
1629 capacity_after_gc, used_after_gc,
1630 minimum_desired_capacity, (double) MinHeapFreeRatio);
1631 expand(expand_bytes);
1632
1633 // No expansion, now see if we want to shrink
1634 } else if (capacity_after_gc > maximum_desired_capacity) {
1635 // Capacity too large, compute shrinking size
1636 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1637 ergo_verbose4(ErgoHeapSizing,
1638 "attempt heap shrinking",
1639 ergo_format_reason("capacity higher than "
1640 "max desired capacity after Full GC")
1641 ergo_format_byte("capacity")
1642 ergo_format_byte("occupancy")
1643 ergo_format_byte_perc("max desired capacity"),
1644 capacity_after_gc, used_after_gc,
1645 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1646 shrink(shrink_bytes);
1647 }
1648 }
1649
1650
1651 HeapWord*
1652 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1653 bool* succeeded) {
1654 assert_at_safepoint(true /* should_be_vm_thread */);
1655
1656 *succeeded = true;
1657 // Let's attempt the allocation first.
1658 HeapWord* result =
1659 attempt_allocation_at_safepoint(word_size,
1660 false /* expect_null_mutator_alloc_region */);
1661 if (result != NULL) {
1662 assert(*succeeded, "sanity");
1663 return result;
1664 }
1665
1666 // In a G1 heap, we're supposed to keep allocation from failing by
1667 // incremental pauses. Therefore, at least for now, we'll favor
1668 // expansion over collection. (This might change in the future if we can
1669 // do something smarter than full collection to satisfy a failed alloc.)
1670 result = expand_and_allocate(word_size);
1671 if (result != NULL) {
1672 assert(*succeeded, "sanity");
1673 return result;
1674 }
1675
1676 // Expansion didn't work, we'll try to do a Full GC.
1677 bool gc_succeeded = do_collection(false, /* explicit_gc */
1678 false, /* clear_all_soft_refs */
1679 word_size);
1680 if (!gc_succeeded) {
1681 *succeeded = false;
1682 return NULL;
1683 }
1684
1685 // Retry the allocation
1686 result = attempt_allocation_at_safepoint(word_size,
1687 true /* expect_null_mutator_alloc_region */);
1688 if (result != NULL) {
1689 assert(*succeeded, "sanity");
1690 return result;
1691 }
1692
1693 // Then, try a Full GC that will collect all soft references.
1694 gc_succeeded = do_collection(false, /* explicit_gc */
1695 true, /* clear_all_soft_refs */
1696 word_size);
1697 if (!gc_succeeded) {
1698 *succeeded = false;
1699 return NULL;
1700 }
1701
1702 // Retry the allocation once more
1703 result = attempt_allocation_at_safepoint(word_size,
1704 true /* expect_null_mutator_alloc_region */);
1705 if (result != NULL) {
1706 assert(*succeeded, "sanity");
1707 return result;
1708 }
1709
1710 assert(!collector_policy()->should_clear_all_soft_refs(),
1711 "Flag should have been handled and cleared prior to this point");
1712
1713 // What else? We might try synchronous finalization later. If the total
1714 // space available is large enough for the allocation, then a more
1715 // complete compaction phase than we've tried so far might be
1716 // appropriate.
1717 assert(*succeeded, "sanity");
1718 return NULL;
1719 }
1720
1721 // Attempting to expand the heap sufficiently
1722 // to support an allocation of the given "word_size". If
1723 // successful, perform the allocation and return the address of the
1724 // allocated block, or else "NULL".
1725
1726 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1727 assert_at_safepoint(true /* should_be_vm_thread */);
1728
1729 verify_region_sets_optional();
1730
1731 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1732 ergo_verbose1(ErgoHeapSizing,
1733 "attempt heap expansion",
1734 ergo_format_reason("allocation request failed")
1735 ergo_format_byte("allocation request"),
1736 word_size * HeapWordSize);
1737 if (expand(expand_bytes)) {
1738 _hrs.verify_optional();
1739 verify_region_sets_optional();
1740 return attempt_allocation_at_safepoint(word_size,
1741 false /* expect_null_mutator_alloc_region */);
1742 }
1743 return NULL;
1744 }
1745
1746 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1747 HeapWord* new_end) {
1748 assert(old_end != new_end, "don't call this otherwise");
1749 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1750
1751 // Update the committed mem region.
1752 _g1_committed.set_end(new_end);
1753 // Tell the card table about the update.
1754 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1755 // Tell the BOT about the update.
1756 _bot_shared->resize(_g1_committed.word_size());
1757 // Tell the hot card cache about the update
1758 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1759 }
1760
1761 bool G1CollectedHeap::expand(size_t expand_bytes) {
1762 size_t old_mem_size = _g1_storage.committed_size();
1763 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1764 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1765 HeapRegion::GrainBytes);
1766 ergo_verbose2(ErgoHeapSizing,
1767 "expand the heap",
1768 ergo_format_byte("requested expansion amount")
1769 ergo_format_byte("attempted expansion amount"),
1770 expand_bytes, aligned_expand_bytes);
1771
1772 // First commit the memory.
1773 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1774 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1775 if (successful) {
1776 // Then propagate this update to the necessary data structures.
1777 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1778 update_committed_space(old_end, new_end);
1779
1780 FreeRegionList expansion_list("Local Expansion List");
1781 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1782 assert(mr.start() == old_end, "post-condition");
1783 // mr might be a smaller region than what was requested if
1784 // expand_by() was unable to allocate the HeapRegion instances
1785 assert(mr.end() <= new_end, "post-condition");
1786
1787 size_t actual_expand_bytes = mr.byte_size();
1788 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1789 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1790 "post-condition");
1791 if (actual_expand_bytes < aligned_expand_bytes) {
1792 // We could not expand _hrs to the desired size. In this case we
1793 // need to shrink the committed space accordingly.
1794 assert(mr.end() < new_end, "invariant");
1795
1796 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1797 // First uncommit the memory.
1798 _g1_storage.shrink_by(diff_bytes);
1799 // Then propagate this update to the necessary data structures.
1800 update_committed_space(new_end, mr.end());
1801 }
1802 _free_list.add_as_tail(&expansion_list);
1803
1804 if (_hr_printer.is_active()) {
1805 HeapWord* curr = mr.start();
1806 while (curr < mr.end()) {
1807 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1808 _hr_printer.commit(curr, curr_end);
1809 curr = curr_end;
1810 }
1811 assert(curr == mr.end(), "post-condition");
1812 }
1813 g1_policy()->record_new_heap_size(n_regions());
1814 } else {
1815 ergo_verbose0(ErgoHeapSizing,
1816 "did not expand the heap",
1817 ergo_format_reason("heap expansion operation failed"));
1818 // The expansion of the virtual storage space was unsuccessful.
1819 // Let's see if it was because we ran out of swap.
1820 if (G1ExitOnExpansionFailure &&
1821 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1822 // We had head room...
1823 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1824 }
1825 }
1826 return successful;
1827 }
1828
1829 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1830 size_t old_mem_size = _g1_storage.committed_size();
1831 size_t aligned_shrink_bytes =
1832 ReservedSpace::page_align_size_down(shrink_bytes);
1833 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1834 HeapRegion::GrainBytes);
1835 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1836
1837 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1838 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1839 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1840
1841 ergo_verbose3(ErgoHeapSizing,
1842 "shrink the heap",
1843 ergo_format_byte("requested shrinking amount")
1844 ergo_format_byte("aligned shrinking amount")
1845 ergo_format_byte("attempted shrinking amount"),
1846 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1847 if (num_regions_removed > 0) {
1848 _g1_storage.shrink_by(shrunk_bytes);
1849 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1850
1851 if (_hr_printer.is_active()) {
1852 HeapWord* curr = old_end;
1853 while (curr > new_end) {
1854 HeapWord* curr_end = curr;
1855 curr -= HeapRegion::GrainWords;
1856 _hr_printer.uncommit(curr, curr_end);
1857 }
1858 }
1859
1860 _expansion_regions += num_regions_removed;
1861 update_committed_space(old_end, new_end);
1862 HeapRegionRemSet::shrink_heap(n_regions());
1863 g1_policy()->record_new_heap_size(n_regions());
1864 } else {
1865 ergo_verbose0(ErgoHeapSizing,
1866 "did not shrink the heap",
1867 ergo_format_reason("heap shrinking operation failed"));
1868 }
1869 }
1870
1871 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1872 verify_region_sets_optional();
1873
1874 // We should only reach here at the end of a Full GC which means we
1875 // should not not be holding to any GC alloc regions. The method
1876 // below will make sure of that and do any remaining clean up.
1877 abandon_gc_alloc_regions();
1878
1879 // Instead of tearing down / rebuilding the free lists here, we
1880 // could instead use the remove_all_pending() method on free_list to
1881 // remove only the ones that we need to remove.
1882 tear_down_region_sets(true /* free_list_only */);
1883 shrink_helper(shrink_bytes);
1884 rebuild_region_sets(true /* free_list_only */);
1885
1886 _hrs.verify_optional();
1887 verify_region_sets_optional();
1888 }
1889
1890 // Public methods.
1891
1892 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1893 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1894 #endif // _MSC_VER
1895
1896
1897 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1898 SharedHeap(policy_),
1899 _g1_policy(policy_),
1900 _dirty_card_queue_set(false),
1901 _into_cset_dirty_card_queue_set(false),
1902 _is_alive_closure_cm(this),
1903 _is_alive_closure_stw(this),
1904 _ref_processor_cm(NULL),
1905 _ref_processor_stw(NULL),
1906 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1907 _bot_shared(NULL),
1908 _evac_failure_scan_stack(NULL) ,
1909 _mark_in_progress(false),
1910 _cg1r(NULL), _summary_bytes_used(0),
1911 _g1mm(NULL),
1912 _refine_cte_cl(NULL),
1913 _full_collection(false),
1914 _free_list("Master Free List"),
1915 _secondary_free_list("Secondary Free List"),
1916 _old_set("Old Set"),
1917 _humongous_set("Master Humongous Set"),
1918 _free_regions_coming(false),
1919 _young_list(new YoungList(this)),
1920 _gc_time_stamp(0),
1921 _retained_old_gc_alloc_region(NULL),
1922 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1923 _old_plab_stats(OldPLABSize, PLABWeight),
1924 _expand_heap_after_alloc_failure(true),
1925 _surviving_young_words(NULL),
1926 _old_marking_cycles_started(0),
1927 _old_marking_cycles_completed(0),
1928 _in_cset_fast_test(NULL),
1929 _in_cset_fast_test_base(NULL),
1930 _dirty_cards_region_list(NULL),
1931 _worker_cset_start_region(NULL),
1932 _worker_cset_start_region_time_stamp(NULL) {
1933 _g1h = this; // To catch bugs.
1934 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1935 vm_exit_during_initialization("Failed necessary allocation.");
1936 }
1937
1938 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1939
1940 int n_queues = MAX2((int)ParallelGCThreads, 1);
1941 _task_queues = new RefToScanQueueSet(n_queues);
1942
1943 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1944 assert(n_rem_sets > 0, "Invariant.");
1945
1946 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1947 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1948
1949 for (int i = 0; i < n_queues; i++) {
1950 RefToScanQueue* q = new RefToScanQueue();
1951 q->initialize();
1952 _task_queues->register_queue(i, q);
1953 }
1954
1955 clear_cset_start_regions();
1956
1957 // Initialize the G1EvacuationFailureALot counters and flags.
1958 NOT_PRODUCT(reset_evacuation_should_fail();)
1959
1960 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1961 }
1962
1963 jint G1CollectedHeap::initialize() {
1964 CollectedHeap::pre_initialize();
1965 os::enable_vtime();
1966
1967 G1Log::init();
1968
1969 // Necessary to satisfy locking discipline assertions.
1970
1971 MutexLocker x(Heap_lock);
1972
1973 // We have to initialize the printer before committing the heap, as
1974 // it will be used then.
1975 _hr_printer.set_active(G1PrintHeapRegions);
1976
1977 // While there are no constraints in the GC code that HeapWordSize
1978 // be any particular value, there are multiple other areas in the
1979 // system which believe this to be true (e.g. oop->object_size in some
1980 // cases incorrectly returns the size in wordSize units rather than
1981 // HeapWordSize).
1982 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1983
1984 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1985 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1986
1987 // Ensure that the sizes are properly aligned.
1988 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1989 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1990
1991 _cg1r = new ConcurrentG1Refine(this);
1992
1993 // Reserve the maximum.
1994
1995 // When compressed oops are enabled, the preferred heap base
1996 // is calculated by subtracting the requested size from the
1997 // 32Gb boundary and using the result as the base address for
1998 // heap reservation. If the requested size is not aligned to
1999 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2000 // into the ReservedHeapSpace constructor) then the actual
2001 // base of the reserved heap may end up differing from the
2002 // address that was requested (i.e. the preferred heap base).
2003 // If this happens then we could end up using a non-optimal
2004 // compressed oops mode.
2005
2006 // Since max_byte_size is aligned to the size of a heap region (checked
2007 // above).
2008 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2009
2010 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2011 HeapRegion::GrainBytes);
2012
2013 // It is important to do this in a way such that concurrent readers can't
2014 // temporarily think somethings in the heap. (I've actually seen this
2015 // happen in asserts: DLD.)
2016 _reserved.set_word_size(0);
2017 _reserved.set_start((HeapWord*)heap_rs.base());
2018 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2019
2020 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2021
2022 // Create the gen rem set (and barrier set) for the entire reserved region.
2023 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2024 set_barrier_set(rem_set()->bs());
2025 if (barrier_set()->is_a(BarrierSet::ModRef)) {
2026 _mr_bs = (ModRefBarrierSet*)_barrier_set;
2027 } else {
2028 vm_exit_during_initialization("G1 requires a mod ref bs.");
2029 return JNI_ENOMEM;
2030 }
2031
2032 // Also create a G1 rem set.
2033 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
2034 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
2035 } else {
2036 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
2037 return JNI_ENOMEM;
2038 }
2039
2040 // Carve out the G1 part of the heap.
2041
2042 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2043 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2044 g1_rs.size()/HeapWordSize);
2045
2046 _g1_storage.initialize(g1_rs, 0);
2047 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2048 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2049 (HeapWord*) _g1_reserved.end(),
2050 _expansion_regions);
2051
2052 // Do later initialization work for concurrent refinement.
2053 _cg1r->init();
2054
2055 // 6843694 - ensure that the maximum region index can fit
2056 // in the remembered set structures.
2057 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2058 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2059
2060 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2061 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2062 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2063 "too many cards per region");
2064
2065 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2066
2067 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2068 heap_word_size(init_byte_size));
2069
2070 _g1h = this;
2071
2072 _in_cset_fast_test_length = max_regions();
2073 _in_cset_fast_test_base =
2074 NEW_C_HEAP_ARRAY(bool, (size_t) _in_cset_fast_test_length, mtGC);
2075
2076 // We're biasing _in_cset_fast_test to avoid subtracting the
2077 // beginning of the heap every time we want to index; basically
2078 // it's the same with what we do with the card table.
2079 _in_cset_fast_test = _in_cset_fast_test_base -
2080 ((uintx) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2081
2082 // Clear the _cset_fast_test bitmap in anticipation of adding
2083 // regions to the incremental collection set for the first
2084 // evacuation pause.
2085 clear_cset_fast_test();
2086
2087 // Create the ConcurrentMark data structure and thread.
2088 // (Must do this late, so that "max_regions" is defined.)
2089 _cm = new ConcurrentMark(this, heap_rs);
2090 if (_cm == NULL || !_cm->completed_initialization()) {
2091 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2092 return JNI_ENOMEM;
2093 }
2094 _cmThread = _cm->cmThread();
2095
2096 // Initialize the from_card cache structure of HeapRegionRemSet.
2097 HeapRegionRemSet::init_heap(max_regions());
2098
2099 // Now expand into the initial heap size.
2100 if (!expand(init_byte_size)) {
2101 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2102 return JNI_ENOMEM;
2103 }
2104
2105 // Perform any initialization actions delegated to the policy.
2106 g1_policy()->init();
2107
2108 _refine_cte_cl =
2109 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2110 g1_rem_set(),
2111 concurrent_g1_refine());
2112 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2113
2114 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2115 SATB_Q_FL_lock,
2116 G1SATBProcessCompletedThreshold,
2117 Shared_SATB_Q_lock);
2118
2119 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2120 DirtyCardQ_FL_lock,
2121 concurrent_g1_refine()->yellow_zone(),
2122 concurrent_g1_refine()->red_zone(),
2123 Shared_DirtyCardQ_lock);
2124
2125 if (G1DeferredRSUpdate) {
2126 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2127 DirtyCardQ_FL_lock,
2128 -1, // never trigger processing
2129 -1, // no limit on length
2130 Shared_DirtyCardQ_lock,
2131 &JavaThread::dirty_card_queue_set());
2132 }
2133
2134 // Initialize the card queue set used to hold cards containing
2135 // references into the collection set.
2136 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2137 DirtyCardQ_FL_lock,
2138 -1, // never trigger processing
2139 -1, // no limit on length
2140 Shared_DirtyCardQ_lock,
2141 &JavaThread::dirty_card_queue_set());
2142
2143 // In case we're keeping closure specialization stats, initialize those
2144 // counts and that mechanism.
2145 SpecializationStats::clear();
2146
2147 // Here we allocate the dummy full region that is required by the
2148 // G1AllocRegion class. If we don't pass an address in the reserved
2149 // space here, lots of asserts fire.
2150
2151 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2152 _g1_reserved.start());
2153 // We'll re-use the same region whether the alloc region will
2154 // require BOT updates or not and, if it doesn't, then a non-young
2155 // region will complain that it cannot support allocations without
2156 // BOT updates. So we'll tag the dummy region as young to avoid that.
2157 dummy_region->set_young();
2158 // Make sure it's full.
2159 dummy_region->set_top(dummy_region->end());
2160 G1AllocRegion::setup(this, dummy_region);
2161
2162 init_mutator_alloc_region();
2163
2164 // Do create of the monitoring and management support so that
2165 // values in the heap have been properly initialized.
2166 _g1mm = new G1MonitoringSupport(this);
2167
2168 return JNI_OK;
2169 }
2170
2171 void G1CollectedHeap::ref_processing_init() {
2172 // Reference processing in G1 currently works as follows:
2173 //
2174 // * There are two reference processor instances. One is
2175 // used to record and process discovered references
2176 // during concurrent marking; the other is used to
2177 // record and process references during STW pauses
2178 // (both full and incremental).
2179 // * Both ref processors need to 'span' the entire heap as
2180 // the regions in the collection set may be dotted around.
2181 //
2182 // * For the concurrent marking ref processor:
2183 // * Reference discovery is enabled at initial marking.
2184 // * Reference discovery is disabled and the discovered
2185 // references processed etc during remarking.
2186 // * Reference discovery is MT (see below).
2187 // * Reference discovery requires a barrier (see below).
2188 // * Reference processing may or may not be MT
2189 // (depending on the value of ParallelRefProcEnabled
2190 // and ParallelGCThreads).
2191 // * A full GC disables reference discovery by the CM
2192 // ref processor and abandons any entries on it's
2193 // discovered lists.
2194 //
2195 // * For the STW processor:
2196 // * Non MT discovery is enabled at the start of a full GC.
2197 // * Processing and enqueueing during a full GC is non-MT.
2198 // * During a full GC, references are processed after marking.
2199 //
2200 // * Discovery (may or may not be MT) is enabled at the start
2201 // of an incremental evacuation pause.
2202 // * References are processed near the end of a STW evacuation pause.
2203 // * For both types of GC:
2204 // * Discovery is atomic - i.e. not concurrent.
2205 // * Reference discovery will not need a barrier.
2206
2207 SharedHeap::ref_processing_init();
2208 MemRegion mr = reserved_region();
2209
2210 // Concurrent Mark ref processor
2211 _ref_processor_cm =
2212 new ReferenceProcessor(mr, // span
2213 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2214 // mt processing
2215 (int) ParallelGCThreads,
2216 // degree of mt processing
2217 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2218 // mt discovery
2219 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2220 // degree of mt discovery
2221 false,
2222 // Reference discovery is not atomic
2223 &_is_alive_closure_cm,
2224 // is alive closure
2225 // (for efficiency/performance)
2226 true);
2227 // Setting next fields of discovered
2228 // lists requires a barrier.
2229
2230 // STW ref processor
2231 _ref_processor_stw =
2232 new ReferenceProcessor(mr, // span
2233 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2234 // mt processing
2235 MAX2((int)ParallelGCThreads, 1),
2236 // degree of mt processing
2237 (ParallelGCThreads > 1),
2238 // mt discovery
2239 MAX2((int)ParallelGCThreads, 1),
2240 // degree of mt discovery
2241 true,
2242 // Reference discovery is atomic
2243 &_is_alive_closure_stw,
2244 // is alive closure
2245 // (for efficiency/performance)
2246 false);
2247 // Setting next fields of discovered
2248 // lists requires a barrier.
2249 }
2250
2251 size_t G1CollectedHeap::capacity() const {
2252 return _g1_committed.byte_size();
2253 }
2254
2255 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2256 assert(!hr->continuesHumongous(), "pre-condition");
2257 hr->reset_gc_time_stamp();
2258 if (hr->startsHumongous()) {
2259 uint first_index = hr->hrs_index() + 1;
2260 uint last_index = hr->last_hc_index();
2261 for (uint i = first_index; i < last_index; i += 1) {
2262 HeapRegion* chr = region_at(i);
2263 assert(chr->continuesHumongous(), "sanity");
2264 chr->reset_gc_time_stamp();
2265 }
2266 }
2267 }
2268
2269 #ifndef PRODUCT
2270 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2271 private:
2272 unsigned _gc_time_stamp;
2273 bool _failures;
2274
2275 public:
2276 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2277 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2278
2279 virtual bool doHeapRegion(HeapRegion* hr) {
2280 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2281 if (_gc_time_stamp != region_gc_time_stamp) {
2282 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2283 "expected %d", HR_FORMAT_PARAMS(hr),
2284 region_gc_time_stamp, _gc_time_stamp);
2285 _failures = true;
2286 }
2287 return false;
2288 }
2289
2290 bool failures() { return _failures; }
2291 };
2292
2293 void G1CollectedHeap::check_gc_time_stamps() {
2294 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2295 heap_region_iterate(&cl);
2296 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2297 }
2298 #endif // PRODUCT
2299
2300 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2301 DirtyCardQueue* into_cset_dcq,
2302 bool concurrent,
2303 int worker_i) {
2304 // Clean cards in the hot card cache
2305 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2306 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2307
2308 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2309 int n_completed_buffers = 0;
2310 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2311 n_completed_buffers++;
2312 }
2313 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2314 dcqs.clear_n_completed_buffers();
2315 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2316 }
2317
2318
2319 // Computes the sum of the storage used by the various regions.
2320
2321 size_t G1CollectedHeap::used() const {
2322 assert(Heap_lock->owner() != NULL,
2323 "Should be owned on this thread's behalf.");
2324 size_t result = _summary_bytes_used;
2325 // Read only once in case it is set to NULL concurrently
2326 HeapRegion* hr = _mutator_alloc_region.get();
2327 if (hr != NULL)
2328 result += hr->used();
2329 return result;
2330 }
2331
2332 size_t G1CollectedHeap::used_unlocked() const {
2333 size_t result = _summary_bytes_used;
2334 return result;
2335 }
2336
2337 class SumUsedClosure: public HeapRegionClosure {
2338 size_t _used;
2339 public:
2340 SumUsedClosure() : _used(0) {}
2341 bool doHeapRegion(HeapRegion* r) {
2342 if (!r->continuesHumongous()) {
2343 _used += r->used();
2344 }
2345 return false;
2346 }
2347 size_t result() { return _used; }
2348 };
2349
2350 size_t G1CollectedHeap::recalculate_used() const {
2351 SumUsedClosure blk;
2352 heap_region_iterate(&blk);
2353 return blk.result();
2354 }
2355
2356 size_t G1CollectedHeap::unsafe_max_alloc() {
2357 if (free_regions() > 0) return HeapRegion::GrainBytes;
2358 // otherwise, is there space in the current allocation region?
2359
2360 // We need to store the current allocation region in a local variable
2361 // here. The problem is that this method doesn't take any locks and
2362 // there may be other threads which overwrite the current allocation
2363 // region field. attempt_allocation(), for example, sets it to NULL
2364 // and this can happen *after* the NULL check here but before the call
2365 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2366 // to be a problem in the optimized build, since the two loads of the
2367 // current allocation region field are optimized away.
2368 HeapRegion* hr = _mutator_alloc_region.get();
2369 if (hr == NULL) {
2370 return 0;
2371 }
2372 return hr->free();
2373 }
2374
2375 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2376 switch (cause) {
2377 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2378 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2379 case GCCause::_g1_humongous_allocation: return true;
2380 default: return false;
2381 }
2382 }
2383
2384 #ifndef PRODUCT
2385 void G1CollectedHeap::allocate_dummy_regions() {
2386 // Let's fill up most of the region
2387 size_t word_size = HeapRegion::GrainWords - 1024;
2388 // And as a result the region we'll allocate will be humongous.
2389 guarantee(isHumongous(word_size), "sanity");
2390
2391 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2392 // Let's use the existing mechanism for the allocation
2393 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2394 if (dummy_obj != NULL) {
2395 MemRegion mr(dummy_obj, word_size);
2396 CollectedHeap::fill_with_object(mr);
2397 } else {
2398 // If we can't allocate once, we probably cannot allocate
2399 // again. Let's get out of the loop.
2400 break;
2401 }
2402 }
2403 }
2404 #endif // !PRODUCT
2405
2406 void G1CollectedHeap::increment_old_marking_cycles_started() {
2407 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2408 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2409 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2410 _old_marking_cycles_started, _old_marking_cycles_completed));
2411
2412 _old_marking_cycles_started++;
2413 }
2414
2415 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2416 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2417
2418 // We assume that if concurrent == true, then the caller is a
2419 // concurrent thread that was joined the Suspendible Thread
2420 // Set. If there's ever a cheap way to check this, we should add an
2421 // assert here.
2422
2423 // Given that this method is called at the end of a Full GC or of a
2424 // concurrent cycle, and those can be nested (i.e., a Full GC can
2425 // interrupt a concurrent cycle), the number of full collections
2426 // completed should be either one (in the case where there was no
2427 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2428 // behind the number of full collections started.
2429
2430 // This is the case for the inner caller, i.e. a Full GC.
2431 assert(concurrent ||
2432 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2433 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2434 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2435 "is inconsistent with _old_marking_cycles_completed = %u",
2436 _old_marking_cycles_started, _old_marking_cycles_completed));
2437
2438 // This is the case for the outer caller, i.e. the concurrent cycle.
2439 assert(!concurrent ||
2440 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2441 err_msg("for outer caller (concurrent cycle): "
2442 "_old_marking_cycles_started = %u "
2443 "is inconsistent with _old_marking_cycles_completed = %u",
2444 _old_marking_cycles_started, _old_marking_cycles_completed));
2445
2446 _old_marking_cycles_completed += 1;
2447
2448 // We need to clear the "in_progress" flag in the CM thread before
2449 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2450 // is set) so that if a waiter requests another System.gc() it doesn't
2451 // incorrectly see that a marking cyle is still in progress.
2452 if (concurrent) {
2453 _cmThread->clear_in_progress();
2454 }
2455
2456 // This notify_all() will ensure that a thread that called
2457 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2458 // and it's waiting for a full GC to finish will be woken up. It is
2459 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2460 FullGCCount_lock->notify_all();
2461 }
2462
2463 void G1CollectedHeap::collect(GCCause::Cause cause) {
2464 assert_heap_not_locked();
2465
2466 unsigned int gc_count_before;
2467 unsigned int old_marking_count_before;
2468 bool retry_gc;
2469
2470 do {
2471 retry_gc = false;
2472
2473 {
2474 MutexLocker ml(Heap_lock);
2475
2476 // Read the GC count while holding the Heap_lock
2477 gc_count_before = total_collections();
2478 old_marking_count_before = _old_marking_cycles_started;
2479 }
2480
2481 if (should_do_concurrent_full_gc(cause)) {
2482 // Schedule an initial-mark evacuation pause that will start a
2483 // concurrent cycle. We're setting word_size to 0 which means that
2484 // we are not requesting a post-GC allocation.
2485 VM_G1IncCollectionPause op(gc_count_before,
2486 0, /* word_size */
2487 true, /* should_initiate_conc_mark */
2488 g1_policy()->max_pause_time_ms(),
2489 cause);
2490
2491 VMThread::execute(&op);
2492 if (!op.pause_succeeded()) {
2493 if (old_marking_count_before == _old_marking_cycles_started) {
2494 retry_gc = op.should_retry_gc();
2495 } else {
2496 // A Full GC happened while we were trying to schedule the
2497 // initial-mark GC. No point in starting a new cycle given
2498 // that the whole heap was collected anyway.
2499 }
2500
2501 if (retry_gc) {
2502 if (GC_locker::is_active_and_needs_gc()) {
2503 GC_locker::stall_until_clear();
2504 }
2505 }
2506 }
2507 } else {
2508 if (cause == GCCause::_gc_locker
2509 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2510
2511 // Schedule a standard evacuation pause. We're setting word_size
2512 // to 0 which means that we are not requesting a post-GC allocation.
2513 VM_G1IncCollectionPause op(gc_count_before,
2514 0, /* word_size */
2515 false, /* should_initiate_conc_mark */
2516 g1_policy()->max_pause_time_ms(),
2517 cause);
2518 VMThread::execute(&op);
2519 } else {
2520 // Schedule a Full GC.
2521 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2522 VMThread::execute(&op);
2523 }
2524 }
2525 } while (retry_gc);
2526 }
2527
2528 bool G1CollectedHeap::is_in(const void* p) const {
2529 if (_g1_committed.contains(p)) {
2530 // Given that we know that p is in the committed space,
2531 // heap_region_containing_raw() should successfully
2532 // return the containing region.
2533 HeapRegion* hr = heap_region_containing_raw(p);
2534 return hr->is_in(p);
2535 } else {
2536 return false;
2537 }
2538 }
2539
2540 // Iteration functions.
2541
2542 // Iterates an OopClosure over all ref-containing fields of objects
2543 // within a HeapRegion.
2544
2545 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2546 MemRegion _mr;
2547 ExtendedOopClosure* _cl;
2548 public:
2549 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2550 : _mr(mr), _cl(cl) {}
2551 bool doHeapRegion(HeapRegion* r) {
2552 if (!r->continuesHumongous()) {
2553 r->oop_iterate(_cl);
2554 }
2555 return false;
2556 }
2557 };
2558
2559 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2560 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2561 heap_region_iterate(&blk);
2562 }
2563
2564 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2565 IterateOopClosureRegionClosure blk(mr, cl);
2566 heap_region_iterate(&blk);
2567 }
2568
2569 // Iterates an ObjectClosure over all objects within a HeapRegion.
2570
2571 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2572 ObjectClosure* _cl;
2573 public:
2574 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2575 bool doHeapRegion(HeapRegion* r) {
2576 if (! r->continuesHumongous()) {
2577 r->object_iterate(_cl);
2578 }
2579 return false;
2580 }
2581 };
2582
2583 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2584 IterateObjectClosureRegionClosure blk(cl);
2585 heap_region_iterate(&blk);
2586 }
2587
2588 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2589 // FIXME: is this right?
2590 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2591 }
2592
2593 // Calls a SpaceClosure on a HeapRegion.
2594
2595 class SpaceClosureRegionClosure: public HeapRegionClosure {
2596 SpaceClosure* _cl;
2597 public:
2598 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2599 bool doHeapRegion(HeapRegion* r) {
2600 _cl->do_space(r);
2601 return false;
2602 }
2603 };
2604
2605 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2606 SpaceClosureRegionClosure blk(cl);
2607 heap_region_iterate(&blk);
2608 }
2609
2610 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2611 _hrs.iterate(cl);
2612 }
2613
2614 void
2615 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2616 uint worker_id,
2617 uint no_of_par_workers,
2618 jint claim_value) {
2619 const uint regions = n_regions();
2620 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2621 no_of_par_workers :
2622 1);
2623 assert(UseDynamicNumberOfGCThreads ||
2624 no_of_par_workers == workers()->total_workers(),
2625 "Non dynamic should use fixed number of workers");
2626 // try to spread out the starting points of the workers
2627 const HeapRegion* start_hr =
2628 start_region_for_worker(worker_id, no_of_par_workers);
2629 const uint start_index = start_hr->hrs_index();
2630
2631 // each worker will actually look at all regions
2632 for (uint count = 0; count < regions; ++count) {
2633 const uint index = (start_index + count) % regions;
2634 assert(0 <= index && index < regions, "sanity");
2635 HeapRegion* r = region_at(index);
2636 // we'll ignore "continues humongous" regions (we'll process them
2637 // when we come across their corresponding "start humongous"
2638 // region) and regions already claimed
2639 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2640 continue;
2641 }
2642 // OK, try to claim it
2643 if (r->claimHeapRegion(claim_value)) {
2644 // success!
2645 assert(!r->continuesHumongous(), "sanity");
2646 if (r->startsHumongous()) {
2647 // If the region is "starts humongous" we'll iterate over its
2648 // "continues humongous" first; in fact we'll do them
2649 // first. The order is important. In on case, calling the
2650 // closure on the "starts humongous" region might de-allocate
2651 // and clear all its "continues humongous" regions and, as a
2652 // result, we might end up processing them twice. So, we'll do
2653 // them first (notice: most closures will ignore them anyway) and
2654 // then we'll do the "starts humongous" region.
2655 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2656 HeapRegion* chr = region_at(ch_index);
2657
2658 // if the region has already been claimed or it's not
2659 // "continues humongous" we're done
2660 if (chr->claim_value() == claim_value ||
2661 !chr->continuesHumongous()) {
2662 break;
2663 }
2664
2665 // Noone should have claimed it directly. We can given
2666 // that we claimed its "starts humongous" region.
2667 assert(chr->claim_value() != claim_value, "sanity");
2668 assert(chr->humongous_start_region() == r, "sanity");
2669
2670 if (chr->claimHeapRegion(claim_value)) {
2671 // we should always be able to claim it; noone else should
2672 // be trying to claim this region
2673
2674 bool res2 = cl->doHeapRegion(chr);
2675 assert(!res2, "Should not abort");
2676
2677 // Right now, this holds (i.e., no closure that actually
2678 // does something with "continues humongous" regions
2679 // clears them). We might have to weaken it in the future,
2680 // but let's leave these two asserts here for extra safety.
2681 assert(chr->continuesHumongous(), "should still be the case");
2682 assert(chr->humongous_start_region() == r, "sanity");
2683 } else {
2684 guarantee(false, "we should not reach here");
2685 }
2686 }
2687 }
2688
2689 assert(!r->continuesHumongous(), "sanity");
2690 bool res = cl->doHeapRegion(r);
2691 assert(!res, "Should not abort");
2692 }
2693 }
2694 }
2695
2696 class ResetClaimValuesClosure: public HeapRegionClosure {
2697 public:
2698 bool doHeapRegion(HeapRegion* r) {
2699 r->set_claim_value(HeapRegion::InitialClaimValue);
2700 return false;
2701 }
2702 };
2703
2704 void G1CollectedHeap::reset_heap_region_claim_values() {
2705 ResetClaimValuesClosure blk;
2706 heap_region_iterate(&blk);
2707 }
2708
2709 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2710 ResetClaimValuesClosure blk;
2711 collection_set_iterate(&blk);
2712 }
2713
2714 #ifdef ASSERT
2715 // This checks whether all regions in the heap have the correct claim
2716 // value. I also piggy-backed on this a check to ensure that the
2717 // humongous_start_region() information on "continues humongous"
2718 // regions is correct.
2719
2720 class CheckClaimValuesClosure : public HeapRegionClosure {
2721 private:
2722 jint _claim_value;
2723 uint _failures;
2724 HeapRegion* _sh_region;
2725
2726 public:
2727 CheckClaimValuesClosure(jint claim_value) :
2728 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2729 bool doHeapRegion(HeapRegion* r) {
2730 if (r->claim_value() != _claim_value) {
2731 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2732 "claim value = %d, should be %d",
2733 HR_FORMAT_PARAMS(r),
2734 r->claim_value(), _claim_value);
2735 ++_failures;
2736 }
2737 if (!r->isHumongous()) {
2738 _sh_region = NULL;
2739 } else if (r->startsHumongous()) {
2740 _sh_region = r;
2741 } else if (r->continuesHumongous()) {
2742 if (r->humongous_start_region() != _sh_region) {
2743 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2744 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2745 HR_FORMAT_PARAMS(r),
2746 r->humongous_start_region(),
2747 _sh_region);
2748 ++_failures;
2749 }
2750 }
2751 return false;
2752 }
2753 uint failures() { return _failures; }
2754 };
2755
2756 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2757 CheckClaimValuesClosure cl(claim_value);
2758 heap_region_iterate(&cl);
2759 return cl.failures() == 0;
2760 }
2761
2762 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2763 private:
2764 jint _claim_value;
2765 uint _failures;
2766
2767 public:
2768 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2769 _claim_value(claim_value), _failures(0) { }
2770
2771 uint failures() { return _failures; }
2772
2773 bool doHeapRegion(HeapRegion* hr) {
2774 assert(hr->in_collection_set(), "how?");
2775 assert(!hr->isHumongous(), "H-region in CSet");
2776 if (hr->claim_value() != _claim_value) {
2777 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2778 "claim value = %d, should be %d",
2779 HR_FORMAT_PARAMS(hr),
2780 hr->claim_value(), _claim_value);
2781 _failures += 1;
2782 }
2783 return false;
2784 }
2785 };
2786
2787 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2788 CheckClaimValuesInCSetHRClosure cl(claim_value);
2789 collection_set_iterate(&cl);
2790 return cl.failures() == 0;
2791 }
2792 #endif // ASSERT
2793
2794 // Clear the cached CSet starting regions and (more importantly)
2795 // the time stamps. Called when we reset the GC time stamp.
2796 void G1CollectedHeap::clear_cset_start_regions() {
2797 assert(_worker_cset_start_region != NULL, "sanity");
2798 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2799
2800 int n_queues = MAX2((int)ParallelGCThreads, 1);
2801 for (int i = 0; i < n_queues; i++) {
2802 _worker_cset_start_region[i] = NULL;
2803 _worker_cset_start_region_time_stamp[i] = 0;
2804 }
2805 }
2806
2807 // Given the id of a worker, obtain or calculate a suitable
2808 // starting region for iterating over the current collection set.
2809 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(int worker_i) {
2810 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2811
2812 HeapRegion* result = NULL;
2813 unsigned gc_time_stamp = get_gc_time_stamp();
2814
2815 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2816 // Cached starting region for current worker was set
2817 // during the current pause - so it's valid.
2818 // Note: the cached starting heap region may be NULL
2819 // (when the collection set is empty).
2820 result = _worker_cset_start_region[worker_i];
2821 assert(result == NULL || result->in_collection_set(), "sanity");
2822 return result;
2823 }
2824
2825 // The cached entry was not valid so let's calculate
2826 // a suitable starting heap region for this worker.
2827
2828 // We want the parallel threads to start their collection
2829 // set iteration at different collection set regions to
2830 // avoid contention.
2831 // If we have:
2832 // n collection set regions
2833 // p threads
2834 // Then thread t will start at region floor ((t * n) / p)
2835
2836 result = g1_policy()->collection_set();
2837 if (G1CollectedHeap::use_parallel_gc_threads()) {
2838 uint cs_size = g1_policy()->cset_region_length();
2839 uint active_workers = workers()->active_workers();
2840 assert(UseDynamicNumberOfGCThreads ||
2841 active_workers == workers()->total_workers(),
2842 "Unless dynamic should use total workers");
2843
2844 uint end_ind = (cs_size * worker_i) / active_workers;
2845 uint start_ind = 0;
2846
2847 if (worker_i > 0 &&
2848 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2849 // Previous workers starting region is valid
2850 // so let's iterate from there
2851 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2852 result = _worker_cset_start_region[worker_i - 1];
2853 }
2854
2855 for (uint i = start_ind; i < end_ind; i++) {
2856 result = result->next_in_collection_set();
2857 }
2858 }
2859
2860 // Note: the calculated starting heap region may be NULL
2861 // (when the collection set is empty).
2862 assert(result == NULL || result->in_collection_set(), "sanity");
2863 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2864 "should be updated only once per pause");
2865 _worker_cset_start_region[worker_i] = result;
2866 OrderAccess::storestore();
2867 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2868 return result;
2869 }
2870
2871 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2872 uint no_of_par_workers) {
2873 uint worker_num =
2874 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2875 assert(UseDynamicNumberOfGCThreads ||
2876 no_of_par_workers == workers()->total_workers(),
2877 "Non dynamic should use fixed number of workers");
2878 const uint start_index = n_regions() * worker_i / worker_num;
2879 return region_at(start_index);
2880 }
2881
2882 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2883 HeapRegion* r = g1_policy()->collection_set();
2884 while (r != NULL) {
2885 HeapRegion* next = r->next_in_collection_set();
2886 if (cl->doHeapRegion(r)) {
2887 cl->incomplete();
2888 return;
2889 }
2890 r = next;
2891 }
2892 }
2893
2894 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2895 HeapRegionClosure *cl) {
2896 if (r == NULL) {
2897 // The CSet is empty so there's nothing to do.
2898 return;
2899 }
2900
2901 assert(r->in_collection_set(),
2902 "Start region must be a member of the collection set.");
2903 HeapRegion* cur = r;
2904 while (cur != NULL) {
2905 HeapRegion* next = cur->next_in_collection_set();
2906 if (cl->doHeapRegion(cur) && false) {
2907 cl->incomplete();
2908 return;
2909 }
2910 cur = next;
2911 }
2912 cur = g1_policy()->collection_set();
2913 while (cur != r) {
2914 HeapRegion* next = cur->next_in_collection_set();
2915 if (cl->doHeapRegion(cur) && false) {
2916 cl->incomplete();
2917 return;
2918 }
2919 cur = next;
2920 }
2921 }
2922
2923 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2924 return n_regions() > 0 ? region_at(0) : NULL;
2925 }
2926
2927
2928 Space* G1CollectedHeap::space_containing(const void* addr) const {
2929 Space* res = heap_region_containing(addr);
2930 return res;
2931 }
2932
2933 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2934 Space* sp = space_containing(addr);
2935 if (sp != NULL) {
2936 return sp->block_start(addr);
2937 }
2938 return NULL;
2939 }
2940
2941 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2942 Space* sp = space_containing(addr);
2943 assert(sp != NULL, "block_size of address outside of heap");
2944 return sp->block_size(addr);
2945 }
2946
2947 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2948 Space* sp = space_containing(addr);
2949 return sp->block_is_obj(addr);
2950 }
2951
2952 bool G1CollectedHeap::supports_tlab_allocation() const {
2953 return true;
2954 }
2955
2956 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2957 return HeapRegion::GrainBytes;
2958 }
2959
2960 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2961 // Return the remaining space in the cur alloc region, but not less than
2962 // the min TLAB size.
2963
2964 // Also, this value can be at most the humongous object threshold,
2965 // since we can't allow tlabs to grow big enough to accomodate
2966 // humongous objects.
2967
2968 HeapRegion* hr = _mutator_alloc_region.get();
2969 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2970 if (hr == NULL) {
2971 return max_tlab_size;
2972 } else {
2973 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2974 }
2975 }
2976
2977 size_t G1CollectedHeap::max_capacity() const {
2978 return _g1_reserved.byte_size();
2979 }
2980
2981 jlong G1CollectedHeap::millis_since_last_gc() {
2982 // assert(false, "NYI");
2983 return 0;
2984 }
2985
2986 void G1CollectedHeap::prepare_for_verify() {
2987 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2988 ensure_parsability(false);
2989 }
2990 g1_rem_set()->prepare_for_verify();
2991 }
2992
2993 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2994 VerifyOption vo) {
2995 switch (vo) {
2996 case VerifyOption_G1UsePrevMarking:
2997 return hr->obj_allocated_since_prev_marking(obj);
2998 case VerifyOption_G1UseNextMarking:
2999 return hr->obj_allocated_since_next_marking(obj);
3000 case VerifyOption_G1UseMarkWord:
3001 return false;
3002 default:
3003 ShouldNotReachHere();
3004 }
3005 return false; // keep some compilers happy
3006 }
3007
3008 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3009 switch (vo) {
3010 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3011 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3012 case VerifyOption_G1UseMarkWord: return NULL;
3013 default: ShouldNotReachHere();
3014 }
3015 return NULL; // keep some compilers happy
3016 }
3017
3018 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3019 switch (vo) {
3020 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3021 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3022 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3023 default: ShouldNotReachHere();
3024 }
3025 return false; // keep some compilers happy
3026 }
3027
3028 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3029 switch (vo) {
3030 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3031 case VerifyOption_G1UseNextMarking: return "NTAMS";
3032 case VerifyOption_G1UseMarkWord: return "NONE";
3033 default: ShouldNotReachHere();
3034 }
3035 return NULL; // keep some compilers happy
3036 }
3037
3038 // TODO: VerifyRootsClosure extends OopsInGenClosure so that we can
3039 // pass it as the perm_blk to SharedHeap::process_strong_roots.
3040 // When process_strong_roots stop calling perm_blk->younger_refs_iterate
3041 // we can change this closure to extend the simpler OopClosure.
3042 class VerifyRootsClosure: public OopsInGenClosure {
3043 private:
3044 G1CollectedHeap* _g1h;
3045 VerifyOption _vo;
3046 bool _failures;
3047 public:
3048 // _vo == UsePrevMarking -> use "prev" marking information,
3049 // _vo == UseNextMarking -> use "next" marking information,
3050 // _vo == UseMarkWord -> use mark word from object header.
3051 VerifyRootsClosure(VerifyOption vo) :
3052 _g1h(G1CollectedHeap::heap()),
3053 _vo(vo),
3054 _failures(false) { }
3055
3056 bool failures() { return _failures; }
3057
3058 template <class T> void do_oop_nv(T* p) {
3059 T heap_oop = oopDesc::load_heap_oop(p);
3060 if (!oopDesc::is_null(heap_oop)) {
3061 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3062 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3063 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3064 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3065 if (_vo == VerifyOption_G1UseMarkWord) {
3066 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3067 }
3068 obj->print_on(gclog_or_tty);
3069 _failures = true;
3070 }
3071 }
3072 }
3073
3074 void do_oop(oop* p) { do_oop_nv(p); }
3075 void do_oop(narrowOop* p) { do_oop_nv(p); }
3076 };
3077
3078 class G1VerifyCodeRootOopClosure: public OopsInGenClosure {
3079 G1CollectedHeap* _g1h;
3080 OopClosure* _root_cl;
3081 nmethod* _nm;
3082 VerifyOption _vo;
3083 bool _failures;
3084
3085 template <class T> void do_oop_work(T* p) {
3086 // First verify that this root is live
3087 _root_cl->do_oop(p);
3088
3089 if (!G1VerifyHeapRegionCodeRoots) {
3090 // We're not verifying the code roots attached to heap region.
3091 return;
3092 }
3093
3094 // Don't check the code roots during marking verification in a full GC
3095 if (_vo == VerifyOption_G1UseMarkWord) {
3096 return;
3097 }
3098
3099 // Now verify that the current nmethod (which contains p) is
3100 // in the code root list of the heap region containing the
3101 // object referenced by p.
3102
3103 T heap_oop = oopDesc::load_heap_oop(p);
3104 if (!oopDesc::is_null(heap_oop)) {
3105 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3106
3107 // Now fetch the region containing the object
3108 HeapRegion* hr = _g1h->heap_region_containing(obj);
3109 HeapRegionRemSet* hrrs = hr->rem_set();
3110 // Verify that the strong code root list for this region
3111 // contains the nmethod
3112 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3113 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3114 "from nmethod "PTR_FORMAT" not in strong "
3115 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3116 p, _nm, hr->bottom(), hr->end());
3117 _failures = true;
3118 }
3119 }
3120 }
3121
3122 public:
3123 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3124 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3125
3126 void do_oop(oop* p) { do_oop_work(p); }
3127 void do_oop(narrowOop* p) { do_oop_work(p); }
3128
3129 void set_nmethod(nmethod* nm) { _nm = nm; }
3130 bool failures() { return _failures; }
3131 };
3132
3133 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3134 G1VerifyCodeRootOopClosure* _oop_cl;
3135
3136 public:
3137 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3138 _oop_cl(oop_cl) {}
3139
3140 void do_code_blob(CodeBlob* cb) {
3141 nmethod* nm = cb->as_nmethod_or_null();
3142 if (nm != NULL) {
3143 _oop_cl->set_nmethod(nm);
3144 nm->oops_do(_oop_cl);
3145 }
3146 }
3147 };
3148
3149 class YoungRefCounterClosure : public OopClosure {
3150 G1CollectedHeap* _g1h;
3151 int _count;
3152 public:
3153 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3154 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3155 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3156
3157 int count() { return _count; }
3158 void reset_count() { _count = 0; };
3159 };
3160
3161 class VerifyKlassClosure: public KlassClosure {
3162 YoungRefCounterClosure _young_ref_counter_closure;
3163 OopClosure *_oop_closure;
3164 public:
3165 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3166 void do_klass(Klass* k) {
3167 k->oops_do(_oop_closure);
3168
3169 _young_ref_counter_closure.reset_count();
3170 k->oops_do(&_young_ref_counter_closure);
3171 if (_young_ref_counter_closure.count() > 0) {
3172 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3173 }
3174 }
3175 };
3176
3177 class VerifyLivenessOopClosure: public OopClosure {
3178 G1CollectedHeap* _g1h;
3179 VerifyOption _vo;
3180 public:
3181 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3182 _g1h(g1h), _vo(vo)
3183 { }
3184 void do_oop(narrowOop *p) { do_oop_work(p); }
3185 void do_oop( oop *p) { do_oop_work(p); }
3186
3187 template <class T> void do_oop_work(T *p) {
3188 oop obj = oopDesc::load_decode_heap_oop(p);
3189 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3190 "Dead object referenced by a not dead object");
3191 }
3192 };
3193
3194 class VerifyObjsInRegionClosure: public ObjectClosure {
3195 private:
3196 G1CollectedHeap* _g1h;
3197 size_t _live_bytes;
3198 HeapRegion *_hr;
3199 VerifyOption _vo;
3200 public:
3201 // _vo == UsePrevMarking -> use "prev" marking information,
3202 // _vo == UseNextMarking -> use "next" marking information,
3203 // _vo == UseMarkWord -> use mark word from object header.
3204 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3205 : _live_bytes(0), _hr(hr), _vo(vo) {
3206 _g1h = G1CollectedHeap::heap();
3207 }
3208 void do_object(oop o) {
3209 VerifyLivenessOopClosure isLive(_g1h, _vo);
3210 assert(o != NULL, "Huh?");
3211 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3212 // If the object is alive according to the mark word,
3213 // then verify that the marking information agrees.
3214 // Note we can't verify the contra-positive of the
3215 // above: if the object is dead (according to the mark
3216 // word), it may not be marked, or may have been marked
3217 // but has since became dead, or may have been allocated
3218 // since the last marking.
3219 if (_vo == VerifyOption_G1UseMarkWord) {
3220 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3221 }
3222
3223 o->oop_iterate_no_header(&isLive);
3224 if (!_hr->obj_allocated_since_prev_marking(o)) {
3225 size_t obj_size = o->size(); // Make sure we don't overflow
3226 _live_bytes += (obj_size * HeapWordSize);
3227 }
3228 }
3229 }
3230 size_t live_bytes() { return _live_bytes; }
3231 };
3232
3233 class PrintObjsInRegionClosure : public ObjectClosure {
3234 HeapRegion *_hr;
3235 G1CollectedHeap *_g1;
3236 public:
3237 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3238 _g1 = G1CollectedHeap::heap();
3239 };
3240
3241 void do_object(oop o) {
3242 if (o != NULL) {
3243 HeapWord *start = (HeapWord *) o;
3244 size_t word_sz = o->size();
3245 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3246 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3247 (void*) o, word_sz,
3248 _g1->isMarkedPrev(o),
3249 _g1->isMarkedNext(o),
3250 _hr->obj_allocated_since_prev_marking(o));
3251 HeapWord *end = start + word_sz;
3252 HeapWord *cur;
3253 int *val;
3254 for (cur = start; cur < end; cur++) {
3255 val = (int *) cur;
3256 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3257 }
3258 }
3259 }
3260 };
3261
3262 class VerifyRegionClosure: public HeapRegionClosure {
3263 private:
3264 bool _par;
3265 VerifyOption _vo;
3266 bool _failures;
3267 public:
3268 // _vo == UsePrevMarking -> use "prev" marking information,
3269 // _vo == UseNextMarking -> use "next" marking information,
3270 // _vo == UseMarkWord -> use mark word from object header.
3271 VerifyRegionClosure(bool par, VerifyOption vo)
3272 : _par(par),
3273 _vo(vo),
3274 _failures(false) {}
3275
3276 bool failures() {
3277 return _failures;
3278 }
3279
3280 bool doHeapRegion(HeapRegion* r) {
3281 if (!r->continuesHumongous()) {
3282 bool failures = false;
3283 r->verify(_vo, &failures);
3284 if (failures) {
3285 _failures = true;
3286 } else {
3287 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3288 r->object_iterate(¬_dead_yet_cl);
3289 if (_vo != VerifyOption_G1UseNextMarking) {
3290 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3291 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3292 "max_live_bytes "SIZE_FORMAT" "
3293 "< calculated "SIZE_FORMAT,
3294 r->bottom(), r->end(),
3295 r->max_live_bytes(),
3296 not_dead_yet_cl.live_bytes());
3297 _failures = true;
3298 }
3299 } else {
3300 // When vo == UseNextMarking we cannot currently do a sanity
3301 // check on the live bytes as the calculation has not been
3302 // finalized yet.
3303 }
3304 }
3305 }
3306 return false; // stop the region iteration if we hit a failure
3307 }
3308 };
3309
3310 // This is the task used for parallel verification of the heap regions
3311
3312 class G1ParVerifyTask: public AbstractGangTask {
3313 private:
3314 G1CollectedHeap* _g1h;
3315 VerifyOption _vo;
3316 bool _failures;
3317
3318 public:
3319 // _vo == UsePrevMarking -> use "prev" marking information,
3320 // _vo == UseNextMarking -> use "next" marking information,
3321 // _vo == UseMarkWord -> use mark word from object header.
3322 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3323 AbstractGangTask("Parallel verify task"),
3324 _g1h(g1h),
3325 _vo(vo),
3326 _failures(false) { }
3327
3328 bool failures() {
3329 return _failures;
3330 }
3331
3332 void work(uint worker_id) {
3333 HandleMark hm;
3334 VerifyRegionClosure blk(true, _vo);
3335 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3336 _g1h->workers()->active_workers(),
3337 HeapRegion::ParVerifyClaimValue);
3338 if (blk.failures()) {
3339 _failures = true;
3340 }
3341 }
3342 };
3343
3344 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3345 if (SafepointSynchronize::is_at_safepoint()) {
3346 assert(Thread::current()->is_VM_thread(),
3347 "Expected to be executed serially by the VM thread at this point");
3348
3349 if (!silent) { gclog_or_tty->print("Roots "); }
3350 VerifyRootsClosure rootsCl(vo);
3351 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3352 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3353 VerifyKlassClosure klassCl(this, &rootsCl);
3354
3355 // We apply the relevant closures to all the oops in the
3356 // system dictionary, the string table and the code cache.
3357 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3358
3359 // Need cleared claim bits for the strong roots processing
3360 ClassLoaderDataGraph::clear_claimed_marks();
3361
3362 process_strong_roots(true, // activate StrongRootsScope
3363 false, // we set "is scavenging" to false,
3364 // so we don't reset the dirty cards.
3365 ScanningOption(so), // roots scanning options
3366 &rootsCl,
3367 &blobsCl,
3368 &klassCl
3369 );
3370
3371 bool failures = rootsCl.failures() || codeRootsCl.failures();
3372
3373 if (vo != VerifyOption_G1UseMarkWord) {
3374 // If we're verifying during a full GC then the region sets
3375 // will have been torn down at the start of the GC. Therefore
3376 // verifying the region sets will fail. So we only verify
3377 // the region sets when not in a full GC.
3378 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3379 verify_region_sets();
3380 }
3381
3382 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3383 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3384 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3385 "sanity check");
3386
3387 G1ParVerifyTask task(this, vo);
3388 assert(UseDynamicNumberOfGCThreads ||
3389 workers()->active_workers() == workers()->total_workers(),
3390 "If not dynamic should be using all the workers");
3391 int n_workers = workers()->active_workers();
3392 set_par_threads(n_workers);
3393 workers()->run_task(&task);
3394 set_par_threads(0);
3395 if (task.failures()) {
3396 failures = true;
3397 }
3398
3399 // Checks that the expected amount of parallel work was done.
3400 // The implication is that n_workers is > 0.
3401 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3402 "sanity check");
3403
3404 reset_heap_region_claim_values();
3405
3406 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3407 "sanity check");
3408 } else {
3409 VerifyRegionClosure blk(false, vo);
3410 heap_region_iterate(&blk);
3411 if (blk.failures()) {
3412 failures = true;
3413 }
3414 }
3415 if (!silent) gclog_or_tty->print("RemSet ");
3416 rem_set()->verify();
3417
3418 if (failures) {
3419 gclog_or_tty->print_cr("Heap:");
3420 // It helps to have the per-region information in the output to
3421 // help us track down what went wrong. This is why we call
3422 // print_extended_on() instead of print_on().
3423 print_extended_on(gclog_or_tty);
3424 gclog_or_tty->print_cr("");
3425 #ifndef PRODUCT
3426 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3427 concurrent_mark()->print_reachable("at-verification-failure",
3428 vo, false /* all */);
3429 }
3430 #endif
3431 gclog_or_tty->flush();
3432 }
3433 guarantee(!failures, "there should not have been any failures");
3434 } else {
3435 if (!silent)
3436 gclog_or_tty->print("(SKIPPING roots, heapRegionSets, heapRegions, remset) ");
3437 }
3438 }
3439
3440 void G1CollectedHeap::verify(bool silent) {
3441 verify(silent, VerifyOption_G1UsePrevMarking);
3442 }
3443
3444 double G1CollectedHeap::verify(bool guard, const char* msg) {
3445 double verify_time_ms = 0.0;
3446
3447 if (guard && total_collections() >= VerifyGCStartAt) {
3448 double verify_start = os::elapsedTime();
3449 HandleMark hm; // Discard invalid handles created during verification
3450 prepare_for_verify();
3451 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3452 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3453 }
3454
3455 return verify_time_ms;
3456 }
3457
3458 void G1CollectedHeap::verify_before_gc() {
3459 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3460 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3461 }
3462
3463 void G1CollectedHeap::verify_after_gc() {
3464 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3465 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3466 }
3467
3468 class PrintRegionClosure: public HeapRegionClosure {
3469 outputStream* _st;
3470 public:
3471 PrintRegionClosure(outputStream* st) : _st(st) {}
3472 bool doHeapRegion(HeapRegion* r) {
3473 r->print_on(_st);
3474 return false;
3475 }
3476 };
3477
3478 void G1CollectedHeap::print_on(outputStream* st) const {
3479 st->print(" %-20s", "garbage-first heap");
3480 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3481 capacity()/K, used_unlocked()/K);
3482 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3483 _g1_storage.low_boundary(),
3484 _g1_storage.high(),
3485 _g1_storage.high_boundary());
3486 st->cr();
3487 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3488 uint young_regions = _young_list->length();
3489 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3490 (size_t) young_regions * HeapRegion::GrainBytes / K);
3491 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3492 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3493 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3494 st->cr();
3495 MetaspaceAux::print_on(st);
3496 }
3497
3498 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3499 print_on(st);
3500
3501 // Print the per-region information.
3502 st->cr();
3503 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3504 "HS=humongous(starts), HC=humongous(continues), "
3505 "CS=collection set, F=free, TS=gc time stamp, "
3506 "PTAMS=previous top-at-mark-start, "
3507 "NTAMS=next top-at-mark-start)");
3508 PrintRegionClosure blk(st);
3509 heap_region_iterate(&blk);
3510 }
3511
3512 void G1CollectedHeap::print_on_error(outputStream* st) const {
3513 this->CollectedHeap::print_on_error(st);
3514
3515 if (_cm != NULL) {
3516 st->cr();
3517 _cm->print_on_error(st);
3518 }
3519 }
3520
3521 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3522 if (G1CollectedHeap::use_parallel_gc_threads()) {
3523 workers()->print_worker_threads_on(st);
3524 }
3525 _cmThread->print_on(st);
3526 st->cr();
3527 _cm->print_worker_threads_on(st);
3528 _cg1r->print_worker_threads_on(st);
3529 }
3530
3531 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3532 if (G1CollectedHeap::use_parallel_gc_threads()) {
3533 workers()->threads_do(tc);
3534 }
3535 tc->do_thread(_cmThread);
3536 _cg1r->threads_do(tc);
3537 }
3538
3539 void G1CollectedHeap::print_tracing_info() const {
3540 // We'll overload this to mean "trace GC pause statistics."
3541 if (TraceGen0Time || TraceGen1Time) {
3542 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3543 // to that.
3544 g1_policy()->print_tracing_info();
3545 }
3546 if (G1SummarizeRSetStats) {
3547 g1_rem_set()->print_summary_info();
3548 }
3549 if (G1SummarizeConcMark) {
3550 concurrent_mark()->print_summary_info();
3551 }
3552 g1_policy()->print_yg_surv_rate_info();
3553 SpecializationStats::print();
3554 }
3555
3556 #ifndef PRODUCT
3557 // Helpful for debugging RSet issues.
3558
3559 class PrintRSetsClosure : public HeapRegionClosure {
3560 private:
3561 const char* _msg;
3562 size_t _occupied_sum;
3563
3564 public:
3565 bool doHeapRegion(HeapRegion* r) {
3566 HeapRegionRemSet* hrrs = r->rem_set();
3567 size_t occupied = hrrs->occupied();
3568 _occupied_sum += occupied;
3569
3570 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3571 HR_FORMAT_PARAMS(r));
3572 if (occupied == 0) {
3573 gclog_or_tty->print_cr(" RSet is empty");
3574 } else {
3575 hrrs->print();
3576 }
3577 gclog_or_tty->print_cr("----------");
3578 return false;
3579 }
3580
3581 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3582 gclog_or_tty->cr();
3583 gclog_or_tty->print_cr("========================================");
3584 gclog_or_tty->print_cr(msg);
3585 gclog_or_tty->cr();
3586 }
3587
3588 ~PrintRSetsClosure() {
3589 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3590 gclog_or_tty->print_cr("========================================");
3591 gclog_or_tty->cr();
3592 }
3593 };
3594
3595 void G1CollectedHeap::print_cset_rsets() {
3596 PrintRSetsClosure cl("Printing CSet RSets");
3597 collection_set_iterate(&cl);
3598 }
3599
3600 void G1CollectedHeap::print_all_rsets() {
3601 PrintRSetsClosure cl("Printing All RSets");;
3602 heap_region_iterate(&cl);
3603 }
3604 #endif // PRODUCT
3605
3606 G1CollectedHeap* G1CollectedHeap::heap() {
3607 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3608 "not a garbage-first heap");
3609 return _g1h;
3610 }
3611
3612 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3613 // always_do_update_barrier = false;
3614 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3615 // Call allocation profiler
3616 AllocationProfiler::iterate_since_last_gc();
3617 // Fill TLAB's and such
3618 ensure_parsability(true);
3619 }
3620
3621 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3622
3623 if (G1SummarizeRSetStats &&
3624 (G1SummarizeRSetStatsPeriod > 0) &&
3625 // we are at the end of the GC. Total collections has already been increased.
3626 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3627 g1_rem_set()->print_periodic_summary_info();
3628 }
3629
3630 // FIXME: what is this about?
3631 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3632 // is set.
3633 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3634 "derived pointer present"));
3635 // always_do_update_barrier = true;
3636
3637 // We have just completed a GC. Update the soft reference
3638 // policy with the new heap occupancy
3639 Universe::update_heap_info_at_gc();
3640 }
3641
3642 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3643 unsigned int gc_count_before,
3644 bool* succeeded) {
3645 assert_heap_not_locked_and_not_at_safepoint();
3646 g1_policy()->record_stop_world_start();
3647 VM_G1IncCollectionPause op(gc_count_before,
3648 word_size,
3649 false, /* should_initiate_conc_mark */
3650 g1_policy()->max_pause_time_ms(),
3651 GCCause::_g1_inc_collection_pause);
3652 VMThread::execute(&op);
3653
3654 HeapWord* result = op.result();
3655 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3656 assert(result == NULL || ret_succeeded,
3657 "the result should be NULL if the VM did not succeed");
3658 *succeeded = ret_succeeded;
3659
3660 assert_heap_not_locked();
3661 return result;
3662 }
3663
3664 void
3665 G1CollectedHeap::doConcurrentMark() {
3666 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3667 if (!_cmThread->in_progress()) {
3668 _cmThread->set_started();
3669 CGC_lock->notify();
3670 }
3671 }
3672
3673 size_t G1CollectedHeap::pending_card_num() {
3674 size_t extra_cards = 0;
3675 JavaThread *curr = Threads::first();
3676 while (curr != NULL) {
3677 DirtyCardQueue& dcq = curr->dirty_card_queue();
3678 extra_cards += dcq.size();
3679 curr = curr->next();
3680 }
3681 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3682 size_t buffer_size = dcqs.buffer_size();
3683 size_t buffer_num = dcqs.completed_buffers_num();
3684
3685 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3686 // in bytes - not the number of 'entries'. We need to convert
3687 // into a number of cards.
3688 return (buffer_size * buffer_num + extra_cards) / oopSize;
3689 }
3690
3691 size_t G1CollectedHeap::cards_scanned() {
3692 return g1_rem_set()->cardsScanned();
3693 }
3694
3695 void
3696 G1CollectedHeap::setup_surviving_young_words() {
3697 assert(_surviving_young_words == NULL, "pre-condition");
3698 uint array_length = g1_policy()->young_cset_region_length();
3699 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3700 if (_surviving_young_words == NULL) {
3701 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3702 "Not enough space for young surv words summary.");
3703 }
3704 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3705 #ifdef ASSERT
3706 for (uint i = 0; i < array_length; ++i) {
3707 assert( _surviving_young_words[i] == 0, "memset above" );
3708 }
3709 #endif // !ASSERT
3710 }
3711
3712 void
3713 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3714 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3715 uint array_length = g1_policy()->young_cset_region_length();
3716 for (uint i = 0; i < array_length; ++i) {
3717 _surviving_young_words[i] += surv_young_words[i];
3718 }
3719 }
3720
3721 void
3722 G1CollectedHeap::cleanup_surviving_young_words() {
3723 guarantee( _surviving_young_words != NULL, "pre-condition" );
3724 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3725 _surviving_young_words = NULL;
3726 }
3727
3728 #ifdef ASSERT
3729 class VerifyCSetClosure: public HeapRegionClosure {
3730 public:
3731 bool doHeapRegion(HeapRegion* hr) {
3732 // Here we check that the CSet region's RSet is ready for parallel
3733 // iteration. The fields that we'll verify are only manipulated
3734 // when the region is part of a CSet and is collected. Afterwards,
3735 // we reset these fields when we clear the region's RSet (when the
3736 // region is freed) so they are ready when the region is
3737 // re-allocated. The only exception to this is if there's an
3738 // evacuation failure and instead of freeing the region we leave
3739 // it in the heap. In that case, we reset these fields during
3740 // evacuation failure handling.
3741 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3742
3743 // Here's a good place to add any other checks we'd like to
3744 // perform on CSet regions.
3745 return false;
3746 }
3747 };
3748 #endif // ASSERT
3749
3750 #if TASKQUEUE_STATS
3751 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3752 st->print_raw_cr("GC Task Stats");
3753 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3754 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3755 }
3756
3757 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3758 print_taskqueue_stats_hdr(st);
3759
3760 TaskQueueStats totals;
3761 const int n = workers() != NULL ? workers()->total_workers() : 1;
3762 for (int i = 0; i < n; ++i) {
3763 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3764 totals += task_queue(i)->stats;
3765 }
3766 st->print_raw("tot "); totals.print(st); st->cr();
3767
3768 DEBUG_ONLY(totals.verify());
3769 }
3770
3771 void G1CollectedHeap::reset_taskqueue_stats() {
3772 const int n = workers() != NULL ? workers()->total_workers() : 1;
3773 for (int i = 0; i < n; ++i) {
3774 task_queue(i)->stats.reset();
3775 }
3776 }
3777 #endif // TASKQUEUE_STATS
3778
3779 void G1CollectedHeap::log_gc_header() {
3780 if (!G1Log::fine()) {
3781 return;
3782 }
3783
3784 gclog_or_tty->date_stamp(PrintGCDateStamps);
3785 gclog_or_tty->stamp(PrintGCTimeStamps);
3786
3787 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3788 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3789 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3790
3791 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3792 }
3793
3794 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3795 if (!G1Log::fine()) {
3796 return;
3797 }
3798
3799 if (G1Log::finer()) {
3800 if (evacuation_failed()) {
3801 gclog_or_tty->print(" (to-space exhausted)");
3802 }
3803 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3804 g1_policy()->phase_times()->note_gc_end();
3805 g1_policy()->phase_times()->print(pause_time_sec);
3806 g1_policy()->print_detailed_heap_transition();
3807 } else {
3808 if (evacuation_failed()) {
3809 gclog_or_tty->print("--");
3810 }
3811 g1_policy()->print_heap_transition();
3812 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3813 }
3814 gclog_or_tty->flush();
3815 }
3816
3817 bool
3818 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3819 assert_at_safepoint(true /* should_be_vm_thread */);
3820 guarantee(!is_gc_active(), "collection is not reentrant");
3821
3822 if (GC_locker::check_active_before_gc()) {
3823 return false;
3824 }
3825
3826 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3827 ResourceMark rm;
3828
3829 print_heap_before_gc();
3830
3831 HRSPhaseSetter x(HRSPhaseEvacuation);
3832 verify_region_sets_optional();
3833 verify_dirty_young_regions();
3834
3835 // This call will decide whether this pause is an initial-mark
3836 // pause. If it is, during_initial_mark_pause() will return true
3837 // for the duration of this pause.
3838 g1_policy()->decide_on_conc_mark_initiation();
3839
3840 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3841 assert(!g1_policy()->during_initial_mark_pause() ||
3842 g1_policy()->gcs_are_young(), "sanity");
3843
3844 // We also do not allow mixed GCs during marking.
3845 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3846
3847 // Record whether this pause is an initial mark. When the current
3848 // thread has completed its logging output and it's safe to signal
3849 // the CM thread, the flag's value in the policy has been reset.
3850 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3851
3852 // Inner scope for scope based logging, timers, and stats collection
3853 {
3854 if (g1_policy()->during_initial_mark_pause()) {
3855 // We are about to start a marking cycle, so we increment the
3856 // full collection counter.
3857 increment_old_marking_cycles_started();
3858 }
3859 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3860
3861 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3862 workers()->active_workers() : 1);
3863 double pause_start_sec = os::elapsedTime();
3864 g1_policy()->phase_times()->note_gc_start(active_workers);
3865 log_gc_header();
3866
3867 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3868 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3869
3870 // If the secondary_free_list is not empty, append it to the
3871 // free_list. No need to wait for the cleanup operation to finish;
3872 // the region allocation code will check the secondary_free_list
3873 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3874 // set, skip this step so that the region allocation code has to
3875 // get entries from the secondary_free_list.
3876 if (!G1StressConcRegionFreeing) {
3877 append_secondary_free_list_if_not_empty_with_lock();
3878 }
3879
3880 assert(check_young_list_well_formed(), "young list should be well formed");
3881 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3882 "sanity check");
3883
3884 // Don't dynamically change the number of GC threads this early. A value of
3885 // 0 is used to indicate serial work. When parallel work is done,
3886 // it will be set.
3887
3888 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3889 IsGCActiveMark x;
3890
3891 gc_prologue(false);
3892 increment_total_collections(false /* full gc */);
3893 increment_gc_time_stamp();
3894
3895 verify_before_gc();
3896
3897 COMPILER2_PRESENT(DerivedPointerTable::clear());
3898
3899 // Please see comment in g1CollectedHeap.hpp and
3900 // G1CollectedHeap::ref_processing_init() to see how
3901 // reference processing currently works in G1.
3902
3903 // Enable discovery in the STW reference processor
3904 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3905 true /*verify_no_refs*/);
3906
3907 {
3908 // We want to temporarily turn off discovery by the
3909 // CM ref processor, if necessary, and turn it back on
3910 // on again later if we do. Using a scoped
3911 // NoRefDiscovery object will do this.
3912 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3913
3914 // Forget the current alloc region (we might even choose it to be part
3915 // of the collection set!).
3916 release_mutator_alloc_region();
3917
3918 // We should call this after we retire the mutator alloc
3919 // region(s) so that all the ALLOC / RETIRE events are generated
3920 // before the start GC event.
3921 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3922
3923 // This timing is only used by the ergonomics to handle our pause target.
3924 // It is unclear why this should not include the full pause. We will
3925 // investigate this in CR 7178365.
3926 //
3927 // Preserving the old comment here if that helps the investigation:
3928 //
3929 // The elapsed time induced by the start time below deliberately elides
3930 // the possible verification above.
3931 double sample_start_time_sec = os::elapsedTime();
3932
3933 #if YOUNG_LIST_VERBOSE
3934 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3935 _young_list->print();
3936 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3937 #endif // YOUNG_LIST_VERBOSE
3938
3939 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3940
3941 double scan_wait_start = os::elapsedTime();
3942 // We have to wait until the CM threads finish scanning the
3943 // root regions as it's the only way to ensure that all the
3944 // objects on them have been correctly scanned before we start
3945 // moving them during the GC.
3946 bool waited = _cm->root_regions()->wait_until_scan_finished();
3947 double wait_time_ms = 0.0;
3948 if (waited) {
3949 double scan_wait_end = os::elapsedTime();
3950 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3951 }
3952 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3953
3954 #if YOUNG_LIST_VERBOSE
3955 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3956 _young_list->print();
3957 #endif // YOUNG_LIST_VERBOSE
3958
3959 if (g1_policy()->during_initial_mark_pause()) {
3960 concurrent_mark()->checkpointRootsInitialPre();
3961 }
3962
3963 #if YOUNG_LIST_VERBOSE
3964 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3965 _young_list->print();
3966 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3967 #endif // YOUNG_LIST_VERBOSE
3968
3969 g1_policy()->finalize_cset(target_pause_time_ms);
3970
3971 _cm->note_start_of_gc();
3972 // We should not verify the per-thread SATB buffers given that
3973 // we have not filtered them yet (we'll do so during the
3974 // GC). We also call this after finalize_cset() to
3975 // ensure that the CSet has been finalized.
3976 _cm->verify_no_cset_oops(true /* verify_stacks */,
3977 true /* verify_enqueued_buffers */,
3978 false /* verify_thread_buffers */,
3979 true /* verify_fingers */);
3980
3981 if (_hr_printer.is_active()) {
3982 HeapRegion* hr = g1_policy()->collection_set();
3983 while (hr != NULL) {
3984 G1HRPrinter::RegionType type;
3985 if (!hr->is_young()) {
3986 type = G1HRPrinter::Old;
3987 } else if (hr->is_survivor()) {
3988 type = G1HRPrinter::Survivor;
3989 } else {
3990 type = G1HRPrinter::Eden;
3991 }
3992 _hr_printer.cset(hr);
3993 hr = hr->next_in_collection_set();
3994 }
3995 }
3996
3997 #ifdef ASSERT
3998 VerifyCSetClosure cl;
3999 collection_set_iterate(&cl);
4000 #endif // ASSERT
4001
4002 setup_surviving_young_words();
4003
4004 // Initialize the GC alloc regions.
4005 init_gc_alloc_regions();
4006
4007 // Actually do the work...
4008 evacuate_collection_set();
4009
4010 // We do this to mainly verify the per-thread SATB buffers
4011 // (which have been filtered by now) since we didn't verify
4012 // them earlier. No point in re-checking the stacks / enqueued
4013 // buffers given that the CSet has not changed since last time
4014 // we checked.
4015 _cm->verify_no_cset_oops(false /* verify_stacks */,
4016 false /* verify_enqueued_buffers */,
4017 true /* verify_thread_buffers */,
4018 true /* verify_fingers */);
4019
4020 free_collection_set(g1_policy()->collection_set());
4021 g1_policy()->clear_collection_set();
4022
4023 cleanup_surviving_young_words();
4024
4025 // Start a new incremental collection set for the next pause.
4026 g1_policy()->start_incremental_cset_building();
4027
4028 // Clear the _cset_fast_test bitmap in anticipation of adding
4029 // regions to the incremental collection set for the next
4030 // evacuation pause.
4031 clear_cset_fast_test();
4032
4033 _young_list->reset_sampled_info();
4034
4035 // Don't check the whole heap at this point as the
4036 // GC alloc regions from this pause have been tagged
4037 // as survivors and moved on to the survivor list.
4038 // Survivor regions will fail the !is_young() check.
4039 assert(check_young_list_empty(false /* check_heap */),
4040 "young list should be empty");
4041
4042 #if YOUNG_LIST_VERBOSE
4043 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4044 _young_list->print();
4045 #endif // YOUNG_LIST_VERBOSE
4046
4047 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4048 _young_list->first_survivor_region(),
4049 _young_list->last_survivor_region());
4050
4051 _young_list->reset_auxilary_lists();
4052
4053 if (evacuation_failed()) {
4054 _summary_bytes_used = recalculate_used();
4055 } else {
4056 // The "used" of the the collection set have already been subtracted
4057 // when they were freed. Add in the bytes evacuated.
4058 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4059 }
4060
4061 if (g1_policy()->during_initial_mark_pause()) {
4062 // We have to do this before we notify the CM threads that
4063 // they can start working to make sure that all the
4064 // appropriate initialization is done on the CM object.
4065 concurrent_mark()->checkpointRootsInitialPost();
4066 set_marking_started();
4067 // Note that we don't actually trigger the CM thread at
4068 // this point. We do that later when we're sure that
4069 // the current thread has completed its logging output.
4070 }
4071
4072 allocate_dummy_regions();
4073
4074 #if YOUNG_LIST_VERBOSE
4075 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4076 _young_list->print();
4077 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4078 #endif // YOUNG_LIST_VERBOSE
4079
4080 init_mutator_alloc_region();
4081
4082 {
4083 size_t expand_bytes = g1_policy()->expansion_amount();
4084 if (expand_bytes > 0) {
4085 size_t bytes_before = capacity();
4086 // No need for an ergo verbose message here,
4087 // expansion_amount() does this when it returns a value > 0.
4088 if (!expand(expand_bytes)) {
4089 // We failed to expand the heap so let's verify that
4090 // committed/uncommitted amount match the backing store
4091 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4092 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4093 }
4094 }
4095 }
4096
4097 // We redo the verificaiton but now wrt to the new CSet which
4098 // has just got initialized after the previous CSet was freed.
4099 _cm->verify_no_cset_oops(true /* verify_stacks */,
4100 true /* verify_enqueued_buffers */,
4101 true /* verify_thread_buffers */,
4102 true /* verify_fingers */);
4103 _cm->note_end_of_gc();
4104
4105 // This timing is only used by the ergonomics to handle our pause target.
4106 // It is unclear why this should not include the full pause. We will
4107 // investigate this in CR 7178365.
4108 double sample_end_time_sec = os::elapsedTime();
4109 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4110 g1_policy()->record_collection_pause_end(pause_time_ms);
4111
4112 MemoryService::track_memory_usage();
4113
4114 // In prepare_for_verify() below we'll need to scan the deferred
4115 // update buffers to bring the RSets up-to-date if
4116 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4117 // the update buffers we'll probably need to scan cards on the
4118 // regions we just allocated to (i.e., the GC alloc
4119 // regions). However, during the last GC we called
4120 // set_saved_mark() on all the GC alloc regions, so card
4121 // scanning might skip the [saved_mark_word()...top()] area of
4122 // those regions (i.e., the area we allocated objects into
4123 // during the last GC). But it shouldn't. Given that
4124 // saved_mark_word() is conditional on whether the GC time stamp
4125 // on the region is current or not, by incrementing the GC time
4126 // stamp here we invalidate all the GC time stamps on all the
4127 // regions and saved_mark_word() will simply return top() for
4128 // all the regions. This is a nicer way of ensuring this rather
4129 // than iterating over the regions and fixing them. In fact, the
4130 // GC time stamp increment here also ensures that
4131 // saved_mark_word() will return top() between pauses, i.e.,
4132 // during concurrent refinement. So we don't need the
4133 // is_gc_active() check to decided which top to use when
4134 // scanning cards (see CR 7039627).
4135 increment_gc_time_stamp();
4136
4137 verify_after_gc();
4138
4139 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4140 ref_processor_stw()->verify_no_references_recorded();
4141
4142 // CM reference discovery will be re-enabled if necessary.
4143 }
4144
4145 // We should do this after we potentially expand the heap so
4146 // that all the COMMIT events are generated before the end GC
4147 // event, and after we retire the GC alloc regions so that all
4148 // RETIRE events are generated before the end GC event.
4149 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4150
4151 if (mark_in_progress()) {
4152 concurrent_mark()->update_g1_committed();
4153 }
4154
4155 #ifdef TRACESPINNING
4156 ParallelTaskTerminator::print_termination_counts();
4157 #endif
4158
4159 gc_epilogue(false);
4160 }
4161
4162 // Print the remainder of the GC log output.
4163 log_gc_footer(os::elapsedTime() - pause_start_sec);
4164
4165 // It is not yet to safe to tell the concurrent mark to
4166 // start as we have some optional output below. We don't want the
4167 // output from the concurrent mark thread interfering with this
4168 // logging output either.
4169
4170 _hrs.verify_optional();
4171 verify_region_sets_optional();
4172
4173 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4174 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4175
4176 print_heap_after_gc();
4177
4178 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4179 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4180 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4181 // before any GC notifications are raised.
4182 g1mm()->update_sizes();
4183 }
4184
4185 // It should now be safe to tell the concurrent mark thread to start
4186 // without its logging output interfering with the logging output
4187 // that came from the pause.
4188
4189 if (should_start_conc_mark) {
4190 // CAUTION: after the doConcurrentMark() call below,
4191 // the concurrent marking thread(s) could be running
4192 // concurrently with us. Make sure that anything after
4193 // this point does not assume that we are the only GC thread
4194 // running. Note: of course, the actual marking work will
4195 // not start until the safepoint itself is released in
4196 // ConcurrentGCThread::safepoint_desynchronize().
4197 doConcurrentMark();
4198 }
4199
4200 return true;
4201 }
4202
4203 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4204 {
4205 size_t gclab_word_size;
4206 switch (purpose) {
4207 case GCAllocForSurvived:
4208 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4209 break;
4210 case GCAllocForTenured:
4211 gclab_word_size = _old_plab_stats.desired_plab_sz();
4212 break;
4213 default:
4214 assert(false, "unknown GCAllocPurpose");
4215 gclab_word_size = _old_plab_stats.desired_plab_sz();
4216 break;
4217 }
4218
4219 // Prevent humongous PLAB sizes for two reasons:
4220 // * PLABs are allocated using a similar paths as oops, but should
4221 // never be in a humongous region
4222 // * Allowing humongous PLABs needlessly churns the region free lists
4223 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4224 }
4225
4226 void G1CollectedHeap::init_mutator_alloc_region() {
4227 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4228 _mutator_alloc_region.init();
4229 }
4230
4231 void G1CollectedHeap::release_mutator_alloc_region() {
4232 _mutator_alloc_region.release();
4233 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4234 }
4235
4236 void G1CollectedHeap::init_gc_alloc_regions() {
4237 assert_at_safepoint(true /* should_be_vm_thread */);
4238
4239 _survivor_gc_alloc_region.init();
4240 _old_gc_alloc_region.init();
4241 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4242 _retained_old_gc_alloc_region = NULL;
4243
4244 // We will discard the current GC alloc region if:
4245 // a) it's in the collection set (it can happen!),
4246 // b) it's already full (no point in using it),
4247 // c) it's empty (this means that it was emptied during
4248 // a cleanup and it should be on the free list now), or
4249 // d) it's humongous (this means that it was emptied
4250 // during a cleanup and was added to the free list, but
4251 // has been subseqently used to allocate a humongous
4252 // object that may be less than the region size).
4253 if (retained_region != NULL &&
4254 !retained_region->in_collection_set() &&
4255 !(retained_region->top() == retained_region->end()) &&
4256 !retained_region->is_empty() &&
4257 !retained_region->isHumongous()) {
4258 retained_region->set_saved_mark();
4259 // The retained region was added to the old region set when it was
4260 // retired. We have to remove it now, since we don't allow regions
4261 // we allocate to in the region sets. We'll re-add it later, when
4262 // it's retired again.
4263 _old_set.remove(retained_region);
4264 bool during_im = g1_policy()->during_initial_mark_pause();
4265 retained_region->note_start_of_copying(during_im);
4266 _old_gc_alloc_region.set(retained_region);
4267 _hr_printer.reuse(retained_region);
4268 }
4269 }
4270
4271 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers) {
4272 _survivor_gc_alloc_region.release();
4273 // If we have an old GC alloc region to release, we'll save it in
4274 // _retained_old_gc_alloc_region. If we don't
4275 // _retained_old_gc_alloc_region will become NULL. This is what we
4276 // want either way so no reason to check explicitly for either
4277 // condition.
4278 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4279
4280 if (ResizePLAB) {
4281 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4282 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4283 }
4284 }
4285
4286 void G1CollectedHeap::abandon_gc_alloc_regions() {
4287 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4288 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4289 _retained_old_gc_alloc_region = NULL;
4290 }
4291
4292 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4293 _drain_in_progress = false;
4294 set_evac_failure_closure(cl);
4295 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4296 }
4297
4298 void G1CollectedHeap::finalize_for_evac_failure() {
4299 assert(_evac_failure_scan_stack != NULL &&
4300 _evac_failure_scan_stack->length() == 0,
4301 "Postcondition");
4302 assert(!_drain_in_progress, "Postcondition");
4303 delete _evac_failure_scan_stack;
4304 _evac_failure_scan_stack = NULL;
4305 }
4306
4307 void G1CollectedHeap::remove_self_forwarding_pointers() {
4308 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4309
4310 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4311
4312 if (G1CollectedHeap::use_parallel_gc_threads()) {
4313 set_par_threads();
4314 workers()->run_task(&rsfp_task);
4315 set_par_threads(0);
4316 } else {
4317 rsfp_task.work(0);
4318 }
4319
4320 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4321
4322 // Reset the claim values in the regions in the collection set.
4323 reset_cset_heap_region_claim_values();
4324
4325 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4326
4327 // Now restore saved marks, if any.
4328 assert(_objs_with_preserved_marks.size() ==
4329 _preserved_marks_of_objs.size(), "Both or none.");
4330 while (!_objs_with_preserved_marks.is_empty()) {
4331 oop obj = _objs_with_preserved_marks.pop();
4332 markOop m = _preserved_marks_of_objs.pop();
4333 obj->set_mark(m);
4334 }
4335 _objs_with_preserved_marks.clear(true);
4336 _preserved_marks_of_objs.clear(true);
4337 }
4338
4339 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4340 _evac_failure_scan_stack->push(obj);
4341 }
4342
4343 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4344 assert(_evac_failure_scan_stack != NULL, "precondition");
4345
4346 while (_evac_failure_scan_stack->length() > 0) {
4347 oop obj = _evac_failure_scan_stack->pop();
4348 _evac_failure_closure->set_region(heap_region_containing(obj));
4349 obj->oop_iterate_backwards(_evac_failure_closure);
4350 }
4351 }
4352
4353 oop
4354 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4355 oop old) {
4356 assert(obj_in_cs(old),
4357 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4358 (HeapWord*) old));
4359 markOop m = old->mark();
4360 oop forward_ptr = old->forward_to_atomic(old);
4361 if (forward_ptr == NULL) {
4362 // Forward-to-self succeeded.
4363
4364 if (_evac_failure_closure != cl) {
4365 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4366 assert(!_drain_in_progress,
4367 "Should only be true while someone holds the lock.");
4368 // Set the global evac-failure closure to the current thread's.
4369 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4370 set_evac_failure_closure(cl);
4371 // Now do the common part.
4372 handle_evacuation_failure_common(old, m);
4373 // Reset to NULL.
4374 set_evac_failure_closure(NULL);
4375 } else {
4376 // The lock is already held, and this is recursive.
4377 assert(_drain_in_progress, "This should only be the recursive case.");
4378 handle_evacuation_failure_common(old, m);
4379 }
4380 return old;
4381 } else {
4382 // Forward-to-self failed. Either someone else managed to allocate
4383 // space for this object (old != forward_ptr) or they beat us in
4384 // self-forwarding it (old == forward_ptr).
4385 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4386 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4387 "should not be in the CSet",
4388 (HeapWord*) old, (HeapWord*) forward_ptr));
4389 return forward_ptr;
4390 }
4391 }
4392
4393 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4394 set_evacuation_failed(true);
4395
4396 preserve_mark_if_necessary(old, m);
4397
4398 HeapRegion* r = heap_region_containing(old);
4399 if (!r->evacuation_failed()) {
4400 r->set_evacuation_failed(true);
4401 _hr_printer.evac_failure(r);
4402 }
4403
4404 push_on_evac_failure_scan_stack(old);
4405
4406 if (!_drain_in_progress) {
4407 // prevent recursion in copy_to_survivor_space()
4408 _drain_in_progress = true;
4409 drain_evac_failure_scan_stack();
4410 _drain_in_progress = false;
4411 }
4412 }
4413
4414 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4415 assert(evacuation_failed(), "Oversaving!");
4416 // We want to call the "for_promotion_failure" version only in the
4417 // case of a promotion failure.
4418 if (m->must_be_preserved_for_promotion_failure(obj)) {
4419 _objs_with_preserved_marks.push(obj);
4420 _preserved_marks_of_objs.push(m);
4421 }
4422 }
4423
4424 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4425 size_t word_size) {
4426 if (purpose == GCAllocForSurvived) {
4427 HeapWord* result = survivor_attempt_allocation(word_size);
4428 if (result != NULL) {
4429 return result;
4430 } else {
4431 // Let's try to allocate in the old gen in case we can fit the
4432 // object there.
4433 return old_attempt_allocation(word_size);
4434 }
4435 } else {
4436 assert(purpose == GCAllocForTenured, "sanity");
4437 HeapWord* result = old_attempt_allocation(word_size);
4438 if (result != NULL) {
4439 return result;
4440 } else {
4441 // Let's try to allocate in the survivors in case we can fit the
4442 // object there.
4443 return survivor_attempt_allocation(word_size);
4444 }
4445 }
4446
4447 ShouldNotReachHere();
4448 // Trying to keep some compilers happy.
4449 return NULL;
4450 }
4451
4452 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4453 ParGCAllocBuffer(gclab_word_size), _retired(false) { }
4454
4455 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
4456 : _g1h(g1h),
4457 _refs(g1h->task_queue(queue_num)),
4458 _dcq(&g1h->dirty_card_queue_set()),
4459 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4460 _g1_rem(g1h->g1_rem_set()),
4461 _hash_seed(17), _queue_num(queue_num),
4462 _term_attempts(0),
4463 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4464 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4465 _age_table(false),
4466 _strong_roots_time(0), _term_time(0),
4467 _alloc_buffer_waste(0), _undo_waste(0) {
4468 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4469 // we "sacrifice" entry 0 to keep track of surviving bytes for
4470 // non-young regions (where the age is -1)
4471 // We also add a few elements at the beginning and at the end in
4472 // an attempt to eliminate cache contention
4473 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4474 uint array_length = PADDING_ELEM_NUM +
4475 real_length +
4476 PADDING_ELEM_NUM;
4477 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4478 if (_surviving_young_words_base == NULL)
4479 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4480 "Not enough space for young surv histo.");
4481 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4482 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4483
4484 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4485 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4486
4487 _start = os::elapsedTime();
4488 }
4489
4490 void
4491 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4492 {
4493 st->print_raw_cr("GC Termination Stats");
4494 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4495 " ------waste (KiB)------");
4496 st->print_raw_cr("thr ms ms % ms % attempts"
4497 " total alloc undo");
4498 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4499 " ------- ------- -------");
4500 }
4501
4502 void
4503 G1ParScanThreadState::print_termination_stats(int i,
4504 outputStream* const st) const
4505 {
4506 const double elapsed_ms = elapsed_time() * 1000.0;
4507 const double s_roots_ms = strong_roots_time() * 1000.0;
4508 const double term_ms = term_time() * 1000.0;
4509 st->print_cr("%3d %9.2f %9.2f %6.2f "
4510 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4511 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4512 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4513 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4514 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4515 alloc_buffer_waste() * HeapWordSize / K,
4516 undo_waste() * HeapWordSize / K);
4517 }
4518
4519 #ifdef ASSERT
4520 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4521 assert(ref != NULL, "invariant");
4522 assert(UseCompressedOops, "sanity");
4523 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4524 oop p = oopDesc::load_decode_heap_oop(ref);
4525 assert(_g1h->is_in_g1_reserved(p),
4526 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4527 return true;
4528 }
4529
4530 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4531 assert(ref != NULL, "invariant");
4532 if (has_partial_array_mask(ref)) {
4533 // Must be in the collection set--it's already been copied.
4534 oop p = clear_partial_array_mask(ref);
4535 assert(_g1h->obj_in_cs(p),
4536 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4537 } else {
4538 oop p = oopDesc::load_decode_heap_oop(ref);
4539 assert(_g1h->is_in_g1_reserved(p),
4540 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4541 }
4542 return true;
4543 }
4544
4545 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4546 if (ref.is_narrow()) {
4547 return verify_ref((narrowOop*) ref);
4548 } else {
4549 return verify_ref((oop*) ref);
4550 }
4551 }
4552 #endif // ASSERT
4553
4554 void G1ParScanThreadState::trim_queue() {
4555 assert(_evac_cl != NULL, "not set");
4556 assert(_evac_failure_cl != NULL, "not set");
4557 assert(_partial_scan_cl != NULL, "not set");
4558
4559 StarTask ref;
4560 do {
4561 // Drain the overflow stack first, so other threads can steal.
4562 while (refs()->pop_overflow(ref)) {
4563 deal_with_reference(ref);
4564 }
4565
4566 while (refs()->pop_local(ref)) {
4567 deal_with_reference(ref);
4568 }
4569 } while (!refs()->is_empty());
4570 }
4571
4572 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4573 G1ParScanThreadState* par_scan_state) :
4574 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4575 _par_scan_state(par_scan_state),
4576 _worker_id(par_scan_state->queue_num()),
4577 _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
4578 _mark_in_progress(_g1->mark_in_progress()) { }
4579
4580 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4581 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>::mark_object(oop obj) {
4582 #ifdef ASSERT
4583 HeapRegion* hr = _g1->heap_region_containing(obj);
4584 assert(hr != NULL, "sanity");
4585 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4586 #endif // ASSERT
4587
4588 // We know that the object is not moving so it's safe to read its size.
4589 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4590 }
4591
4592 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4593 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4594 ::mark_forwarded_object(oop from_obj, oop to_obj) {
4595 #ifdef ASSERT
4596 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4597 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4598 assert(from_obj != to_obj, "should not be self-forwarded");
4599
4600 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4601 assert(from_hr != NULL, "sanity");
4602 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4603
4604 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4605 assert(to_hr != NULL, "sanity");
4606 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4607 #endif // ASSERT
4608
4609 // The object might be in the process of being copied by another
4610 // worker so we cannot trust that its to-space image is
4611 // well-formed. So we have to read its size from its from-space
4612 // image which we know should not be changing.
4613 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4614 }
4615
4616 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4617 oop G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4618 ::copy_to_survivor_space(oop old) {
4619 size_t word_sz = old->size();
4620 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4621 // +1 to make the -1 indexes valid...
4622 int young_index = from_region->young_index_in_cset()+1;
4623 assert( (from_region->is_young() && young_index > 0) ||
4624 (!from_region->is_young() && young_index == 0), "invariant" );
4625 G1CollectorPolicy* g1p = _g1->g1_policy();
4626 markOop m = old->mark();
4627 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4628 : m->age();
4629 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4630 word_sz);
4631 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4632 #ifndef PRODUCT
4633 // Should this evacuation fail?
4634 if (_g1->evacuation_should_fail()) {
4635 if (obj_ptr != NULL) {
4636 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4637 obj_ptr = NULL;
4638 }
4639 }
4640 #endif // !PRODUCT
4641
4642 if (obj_ptr == NULL) {
4643 // This will either forward-to-self, or detect that someone else has
4644 // installed a forwarding pointer.
4645 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4646 return _g1->handle_evacuation_failure_par(cl, old);
4647 }
4648
4649 oop obj = oop(obj_ptr);
4650
4651 // We're going to allocate linearly, so might as well prefetch ahead.
4652 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4653
4654 oop forward_ptr = old->forward_to_atomic(obj);
4655 if (forward_ptr == NULL) {
4656 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4657 if (g1p->track_object_age(alloc_purpose)) {
4658 // We could simply do obj->incr_age(). However, this causes a
4659 // performance issue. obj->incr_age() will first check whether
4660 // the object has a displaced mark by checking its mark word;
4661 // getting the mark word from the new location of the object
4662 // stalls. So, given that we already have the mark word and we
4663 // are about to install it anyway, it's better to increase the
4664 // age on the mark word, when the object does not have a
4665 // displaced mark word. We're not expecting many objects to have
4666 // a displaced marked word, so that case is not optimized
4667 // further (it could be...) and we simply call obj->incr_age().
4668
4669 if (m->has_displaced_mark_helper()) {
4670 // in this case, we have to install the mark word first,
4671 // otherwise obj looks to be forwarded (the old mark word,
4672 // which contains the forward pointer, was copied)
4673 obj->set_mark(m);
4674 obj->incr_age();
4675 } else {
4676 m = m->incr_age();
4677 obj->set_mark(m);
4678 }
4679 _par_scan_state->age_table()->add(obj, word_sz);
4680 } else {
4681 obj->set_mark(m);
4682 }
4683
4684 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4685 surv_young_words[young_index] += word_sz;
4686
4687 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4688 // We keep track of the next start index in the length field of
4689 // the to-space object. The actual length can be found in the
4690 // length field of the from-space object.
4691 arrayOop(obj)->set_length(0);
4692 oop* old_p = set_partial_array_mask(old);
4693 _par_scan_state->push_on_queue(old_p);
4694 } else {
4695 // No point in using the slower heap_region_containing() method,
4696 // given that we know obj is in the heap.
4697 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4698 obj->oop_iterate_backwards(&_scanner);
4699 }
4700 } else {
4701 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4702 obj = forward_ptr;
4703 }
4704 return obj;
4705 }
4706
4707 template <class T>
4708 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4709 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4710 _scanned_klass->record_modified_oops();
4711 }
4712 }
4713
4714 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object>
4715 template <class T>
4716 void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
4717 ::do_oop_work(T* p) {
4718 oop obj = oopDesc::load_decode_heap_oop(p);
4719 assert(barrier != G1BarrierRS || obj != NULL,
4720 "Precondition: G1BarrierRS implies obj is non-NULL");
4721
4722 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4723
4724 // here the null check is implicit in the cset_fast_test() test
4725 if (_g1->in_cset_fast_test(obj)) {
4726 oop forwardee;
4727 if (obj->is_forwarded()) {
4728 forwardee = obj->forwardee();
4729 } else {
4730 forwardee = copy_to_survivor_space(obj);
4731 }
4732 assert(forwardee != NULL, "forwardee should not be NULL");
4733 oopDesc::encode_store_heap_oop(p, forwardee);
4734 if (do_mark_object && forwardee != obj) {
4735 // If the object is self-forwarded we don't need to explicitly
4736 // mark it, the evacuation failure protocol will do so.
4737 mark_forwarded_object(obj, forwardee);
4738 }
4739
4740 // When scanning the RS, we only care about objs in CS.
4741 if (barrier == G1BarrierRS) {
4742 _par_scan_state->update_rs(_from, p, _worker_id);
4743 } else if (barrier == G1BarrierKlass) {
4744 do_klass_barrier(p, forwardee);
4745 }
4746 } else {
4747 // The object is not in collection set. If we're a root scanning
4748 // closure during an initial mark pause (i.e. do_mark_object will
4749 // be true) then attempt to mark the object.
4750 if (do_mark_object && _g1->is_in_g1_reserved(obj)) {
4751 mark_object(obj);
4752 }
4753 }
4754
4755 if (barrier == G1BarrierEvac && obj != NULL) {
4756 _par_scan_state->update_rs(_from, p, _worker_id);
4757 }
4758
4759 if (do_gen_barrier && obj != NULL) {
4760 par_do_barrier(p);
4761 }
4762 }
4763
4764 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4765 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4766
4767 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4768 assert(has_partial_array_mask(p), "invariant");
4769 oop from_obj = clear_partial_array_mask(p);
4770
4771 assert(Universe::heap()->is_in_reserved(from_obj), "must be in heap.");
4772 assert(from_obj->is_objArray(), "must be obj array");
4773 objArrayOop from_obj_array = objArrayOop(from_obj);
4774 // The from-space object contains the real length.
4775 int length = from_obj_array->length();
4776
4777 assert(from_obj->is_forwarded(), "must be forwarded");
4778 oop to_obj = from_obj->forwardee();
4779 assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
4780 objArrayOop to_obj_array = objArrayOop(to_obj);
4781 // We keep track of the next start index in the length field of the
4782 // to-space object.
4783 int next_index = to_obj_array->length();
4784 assert(0 <= next_index && next_index < length,
4785 err_msg("invariant, next index: %d, length: %d", next_index, length));
4786
4787 int start = next_index;
4788 int end = length;
4789 int remainder = end - start;
4790 // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
4791 if (remainder > 2 * ParGCArrayScanChunk) {
4792 end = start + ParGCArrayScanChunk;
4793 to_obj_array->set_length(end);
4794 // Push the remainder before we process the range in case another
4795 // worker has run out of things to do and can steal it.
4796 oop* from_obj_p = set_partial_array_mask(from_obj);
4797 _par_scan_state->push_on_queue(from_obj_p);
4798 } else {
4799 assert(length == end, "sanity");
4800 // We'll process the final range for this object. Restore the length
4801 // so that the heap remains parsable in case of evacuation failure.
4802 to_obj_array->set_length(end);
4803 }
4804 _scanner.set_region(_g1->heap_region_containing_raw(to_obj));
4805 // Process indexes [start,end). It will also process the header
4806 // along with the first chunk (i.e., the chunk with start == 0).
4807 // Note that at this point the length field of to_obj_array is not
4808 // correct given that we are using it to keep track of the next
4809 // start index. oop_iterate_range() (thankfully!) ignores the length
4810 // field and only relies on the start / end parameters. It does
4811 // however return the size of the object which will be incorrect. So
4812 // we have to ignore it even if we wanted to use it.
4813 to_obj_array->oop_iterate_range(&_scanner, start, end);
4814 }
4815
4816 class G1ParEvacuateFollowersClosure : public VoidClosure {
4817 protected:
4818 G1CollectedHeap* _g1h;
4819 G1ParScanThreadState* _par_scan_state;
4820 RefToScanQueueSet* _queues;
4821 ParallelTaskTerminator* _terminator;
4822
4823 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4824 RefToScanQueueSet* queues() { return _queues; }
4825 ParallelTaskTerminator* terminator() { return _terminator; }
4826
4827 public:
4828 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4829 G1ParScanThreadState* par_scan_state,
4830 RefToScanQueueSet* queues,
4831 ParallelTaskTerminator* terminator)
4832 : _g1h(g1h), _par_scan_state(par_scan_state),
4833 _queues(queues), _terminator(terminator) {}
4834
4835 void do_void();
4836
4837 private:
4838 inline bool offer_termination();
4839 };
4840
4841 bool G1ParEvacuateFollowersClosure::offer_termination() {
4842 G1ParScanThreadState* const pss = par_scan_state();
4843 pss->start_term_time();
4844 const bool res = terminator()->offer_termination();
4845 pss->end_term_time();
4846 return res;
4847 }
4848
4849 void G1ParEvacuateFollowersClosure::do_void() {
4850 StarTask stolen_task;
4851 G1ParScanThreadState* const pss = par_scan_state();
4852 pss->trim_queue();
4853
4854 do {
4855 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4856 assert(pss->verify_task(stolen_task), "sanity");
4857 if (stolen_task.is_narrow()) {
4858 pss->deal_with_reference((narrowOop*) stolen_task);
4859 } else {
4860 pss->deal_with_reference((oop*) stolen_task);
4861 }
4862
4863 // We've just processed a reference and we might have made
4864 // available new entries on the queues. So we have to make sure
4865 // we drain the queues as necessary.
4866 pss->trim_queue();
4867 }
4868 } while (!offer_termination());
4869
4870 pss->retire_alloc_buffers();
4871 }
4872
4873 class G1KlassScanClosure : public KlassClosure {
4874 G1ParCopyHelper* _closure;
4875 bool _process_only_dirty;
4876 int _count;
4877 public:
4878 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4879 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4880 void do_klass(Klass* klass) {
4881 // If the klass has not been dirtied we know that there's
4882 // no references into the young gen and we can skip it.
4883 if (!_process_only_dirty || klass->has_modified_oops()) {
4884 // Clean the klass since we're going to scavenge all the metadata.
4885 klass->clear_modified_oops();
4886
4887 // Tell the closure that this klass is the Klass to scavenge
4888 // and is the one to dirty if oops are left pointing into the young gen.
4889 _closure->set_scanned_klass(klass);
4890
4891 klass->oops_do(_closure);
4892
4893 _closure->set_scanned_klass(NULL);
4894 }
4895 _count++;
4896 }
4897 };
4898
4899 class G1ParTask : public AbstractGangTask {
4900 protected:
4901 G1CollectedHeap* _g1h;
4902 RefToScanQueueSet *_queues;
4903 ParallelTaskTerminator _terminator;
4904 uint _n_workers;
4905
4906 Mutex _stats_lock;
4907 Mutex* stats_lock() { return &_stats_lock; }
4908
4909 size_t getNCards() {
4910 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4911 / G1BlockOffsetSharedArray::N_bytes;
4912 }
4913
4914 public:
4915 G1ParTask(G1CollectedHeap* g1h,
4916 RefToScanQueueSet *task_queues)
4917 : AbstractGangTask("G1 collection"),
4918 _g1h(g1h),
4919 _queues(task_queues),
4920 _terminator(0, _queues),
4921 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4922 {}
4923
4924 RefToScanQueueSet* queues() { return _queues; }
4925
4926 RefToScanQueue *work_queue(int i) {
4927 return queues()->queue(i);
4928 }
4929
4930 ParallelTaskTerminator* terminator() { return &_terminator; }
4931
4932 virtual void set_for_termination(int active_workers) {
4933 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4934 // in the young space (_par_seq_tasks) in the G1 heap
4935 // for SequentialSubTasksDone.
4936 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4937 // both of which need setting by set_n_termination().
4938 _g1h->SharedHeap::set_n_termination(active_workers);
4939 _g1h->set_n_termination(active_workers);
4940 terminator()->reset_for_reuse(active_workers);
4941 _n_workers = active_workers;
4942 }
4943
4944 void work(uint worker_id) {
4945 if (worker_id >= _n_workers) return; // no work needed this round
4946
4947 double start_time_ms = os::elapsedTime() * 1000.0;
4948 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4949
4950 {
4951 ResourceMark rm;
4952 HandleMark hm;
4953
4954 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4955
4956 G1ParScanThreadState pss(_g1h, worker_id);
4957 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4958 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4959 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4960
4961 pss.set_evac_closure(&scan_evac_cl);
4962 pss.set_evac_failure_closure(&evac_failure_cl);
4963 pss.set_partial_scan_closure(&partial_scan_cl);
4964
4965 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4966 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
4967
4968 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4969 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4970
4971 bool only_young = _g1h->g1_policy()->gcs_are_young();
4972 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4973 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4974
4975 OopClosure* scan_root_cl = &only_scan_root_cl;
4976 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
4977
4978 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4979 // We also need to mark copied objects.
4980 scan_root_cl = &scan_mark_root_cl;
4981 scan_klasses_cl = &scan_mark_klasses_cl_s;
4982 }
4983
4984 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4985
4986 // Don't scan the scavengable methods in the code cache as part
4987 // of strong root scanning. The code roots that point into a
4988 // region in the collection set are scanned when we scan the
4989 // region's RSet.
4990 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
4991
4992 pss.start_strong_roots();
4993 _g1h->g1_process_strong_roots(/* is scavenging */ true,
4994 SharedHeap::ScanningOption(so),
4995 scan_root_cl,
4996 &push_heap_rs_cl,
4997 scan_klasses_cl,
4998 worker_id);
4999 pss.end_strong_roots();
5000
5001 {
5002 double start = os::elapsedTime();
5003 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5004 evac.do_void();
5005 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5006 double term_ms = pss.term_time()*1000.0;
5007 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5008 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5009 }
5010 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5011 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5012
5013 if (ParallelGCVerbose) {
5014 MutexLocker x(stats_lock());
5015 pss.print_termination_stats(worker_id);
5016 }
5017
5018 assert(pss.refs()->is_empty(), "should be empty");
5019
5020 // Close the inner scope so that the ResourceMark and HandleMark
5021 // destructors are executed here and are included as part of the
5022 // "GC Worker Time".
5023 }
5024
5025 double end_time_ms = os::elapsedTime() * 1000.0;
5026 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5027 }
5028 };
5029
5030 // *** Common G1 Evacuation Stuff
5031
5032 // This method is run in a GC worker.
5033
5034 void
5035 G1CollectedHeap::
5036 g1_process_strong_roots(bool is_scavenging,
5037 ScanningOption so,
5038 OopClosure* scan_non_heap_roots,
5039 OopsInHeapRegionClosure* scan_rs,
5040 G1KlassScanClosure* scan_klasses,
5041 int worker_i) {
5042
5043 // First scan the strong roots
5044 double ext_roots_start = os::elapsedTime();
5045 double closure_app_time_sec = 0.0;
5046
5047 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5048
5049 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5050 // Walk the code cache/strong code roots w/o buffering, because StarTask
5051 // cannot handle unaligned oop locations.
5052 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5053
5054 process_strong_roots(false, // no scoping; this is parallel code
5055 is_scavenging, so,
5056 &buf_scan_non_heap_roots,
5057 &eager_scan_code_roots,
5058 scan_klasses
5059 );
5060
5061 // Now the CM ref_processor roots.
5062 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5063 // We need to treat the discovered reference lists of the
5064 // concurrent mark ref processor as roots and keep entries
5065 // (which are added by the marking threads) on them live
5066 // until they can be processed at the end of marking.
5067 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5068 }
5069
5070 // Finish up any enqueued closure apps (attributed as object copy time).
5071 buf_scan_non_heap_roots.done();
5072
5073 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5074
5075 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5076
5077 double ext_root_time_ms =
5078 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5079
5080 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5081
5082 // During conc marking we have to filter the per-thread SATB buffers
5083 // to make sure we remove any oops into the CSet (which will show up
5084 // as implicitly live).
5085 double satb_filtering_ms = 0.0;
5086 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5087 if (mark_in_progress()) {
5088 double satb_filter_start = os::elapsedTime();
5089
5090 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5091
5092 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5093 }
5094 }
5095 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5096
5097 // If this is an initial mark pause, and we're not scanning
5098 // the entire code cache, we need to mark the oops in the
5099 // strong code root lists for the regions that are not in
5100 // the collection set.
5101 // Note all threads participate in this set of root tasks.
5102 double mark_strong_code_roots_ms = 0.0;
5103 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5104 double mark_strong_roots_start = os::elapsedTime();
5105 mark_strong_code_roots(worker_i);
5106 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5107 }
5108 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5109
5110 // Now scan the complement of the collection set.
5111 if (scan_rs != NULL) {
5112 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5113 }
5114 _process_strong_tasks->all_tasks_completed();
5115 }
5116
5117 void
5118 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5119 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5120 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5121 }
5122
5123 // Weak Reference Processing support
5124
5125 // An always "is_alive" closure that is used to preserve referents.
5126 // If the object is non-null then it's alive. Used in the preservation
5127 // of referent objects that are pointed to by reference objects
5128 // discovered by the CM ref processor.
5129 class G1AlwaysAliveClosure: public BoolObjectClosure {
5130 G1CollectedHeap* _g1;
5131 public:
5132 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5133 bool do_object_b(oop p) {
5134 if (p != NULL) {
5135 return true;
5136 }
5137 return false;
5138 }
5139 };
5140
5141 bool G1STWIsAliveClosure::do_object_b(oop p) {
5142 // An object is reachable if it is outside the collection set,
5143 // or is inside and copied.
5144 return !_g1->obj_in_cs(p) || p->is_forwarded();
5145 }
5146
5147 // Non Copying Keep Alive closure
5148 class G1KeepAliveClosure: public OopClosure {
5149 G1CollectedHeap* _g1;
5150 public:
5151 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5152 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5153 void do_oop( oop* p) {
5154 oop obj = *p;
5155
5156 if (_g1->obj_in_cs(obj)) {
5157 assert( obj->is_forwarded(), "invariant" );
5158 *p = obj->forwardee();
5159 }
5160 }
5161 };
5162
5163 // Copying Keep Alive closure - can be called from both
5164 // serial and parallel code as long as different worker
5165 // threads utilize different G1ParScanThreadState instances
5166 // and different queues.
5167
5168 class G1CopyingKeepAliveClosure: public OopClosure {
5169 G1CollectedHeap* _g1h;
5170 OopClosure* _copy_non_heap_obj_cl;
5171 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5172 G1ParScanThreadState* _par_scan_state;
5173
5174 public:
5175 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5176 OopClosure* non_heap_obj_cl,
5177 OopsInHeapRegionClosure* metadata_obj_cl,
5178 G1ParScanThreadState* pss):
5179 _g1h(g1h),
5180 _copy_non_heap_obj_cl(non_heap_obj_cl),
5181 _copy_metadata_obj_cl(metadata_obj_cl),
5182 _par_scan_state(pss)
5183 {}
5184
5185 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5186 virtual void do_oop( oop* p) { do_oop_work(p); }
5187
5188 template <class T> void do_oop_work(T* p) {
5189 oop obj = oopDesc::load_decode_heap_oop(p);
5190
5191 if (_g1h->obj_in_cs(obj)) {
5192 // If the referent object has been forwarded (either copied
5193 // to a new location or to itself in the event of an
5194 // evacuation failure) then we need to update the reference
5195 // field and, if both reference and referent are in the G1
5196 // heap, update the RSet for the referent.
5197 //
5198 // If the referent has not been forwarded then we have to keep
5199 // it alive by policy. Therefore we have copy the referent.
5200 //
5201 // If the reference field is in the G1 heap then we can push
5202 // on the PSS queue. When the queue is drained (after each
5203 // phase of reference processing) the object and it's followers
5204 // will be copied, the reference field set to point to the
5205 // new location, and the RSet updated. Otherwise we need to
5206 // use the the non-heap or metadata closures directly to copy
5207 // the refernt object and update the pointer, while avoiding
5208 // updating the RSet.
5209
5210 if (_g1h->is_in_g1_reserved(p)) {
5211 _par_scan_state->push_on_queue(p);
5212 } else {
5213 assert(!ClassLoaderDataGraph::contains((address)p),
5214 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5215 PTR_FORMAT, p));
5216 _copy_non_heap_obj_cl->do_oop(p);
5217 }
5218 }
5219 }
5220 };
5221
5222 // Serial drain queue closure. Called as the 'complete_gc'
5223 // closure for each discovered list in some of the
5224 // reference processing phases.
5225
5226 class G1STWDrainQueueClosure: public VoidClosure {
5227 protected:
5228 G1CollectedHeap* _g1h;
5229 G1ParScanThreadState* _par_scan_state;
5230
5231 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5232
5233 public:
5234 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5235 _g1h(g1h),
5236 _par_scan_state(pss)
5237 { }
5238
5239 void do_void() {
5240 G1ParScanThreadState* const pss = par_scan_state();
5241 pss->trim_queue();
5242 }
5243 };
5244
5245 // Parallel Reference Processing closures
5246
5247 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5248 // processing during G1 evacuation pauses.
5249
5250 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5251 private:
5252 G1CollectedHeap* _g1h;
5253 RefToScanQueueSet* _queues;
5254 FlexibleWorkGang* _workers;
5255 int _active_workers;
5256
5257 public:
5258 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5259 FlexibleWorkGang* workers,
5260 RefToScanQueueSet *task_queues,
5261 int n_workers) :
5262 _g1h(g1h),
5263 _queues(task_queues),
5264 _workers(workers),
5265 _active_workers(n_workers)
5266 {
5267 assert(n_workers > 0, "shouldn't call this otherwise");
5268 }
5269
5270 // Executes the given task using concurrent marking worker threads.
5271 virtual void execute(ProcessTask& task);
5272 virtual void execute(EnqueueTask& task);
5273 };
5274
5275 // Gang task for possibly parallel reference processing
5276
5277 class G1STWRefProcTaskProxy: public AbstractGangTask {
5278 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5279 ProcessTask& _proc_task;
5280 G1CollectedHeap* _g1h;
5281 RefToScanQueueSet *_task_queues;
5282 ParallelTaskTerminator* _terminator;
5283
5284 public:
5285 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5286 G1CollectedHeap* g1h,
5287 RefToScanQueueSet *task_queues,
5288 ParallelTaskTerminator* terminator) :
5289 AbstractGangTask("Process reference objects in parallel"),
5290 _proc_task(proc_task),
5291 _g1h(g1h),
5292 _task_queues(task_queues),
5293 _terminator(terminator)
5294 {}
5295
5296 virtual void work(uint worker_id) {
5297 // The reference processing task executed by a single worker.
5298 ResourceMark rm;
5299 HandleMark hm;
5300
5301 G1STWIsAliveClosure is_alive(_g1h);
5302
5303 G1ParScanThreadState pss(_g1h, worker_id);
5304
5305 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5306 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5307 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5308
5309 pss.set_evac_closure(&scan_evac_cl);
5310 pss.set_evac_failure_closure(&evac_failure_cl);
5311 pss.set_partial_scan_closure(&partial_scan_cl);
5312
5313 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5314 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5315
5316 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5317 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5318
5319 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5320 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5321
5322 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5323 // We also need to mark copied objects.
5324 copy_non_heap_cl = ©_mark_non_heap_cl;
5325 copy_metadata_cl = ©_mark_metadata_cl;
5326 }
5327
5328 // Keep alive closure.
5329 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5330
5331 // Complete GC closure
5332 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5333
5334 // Call the reference processing task's work routine.
5335 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5336
5337 // Note we cannot assert that the refs array is empty here as not all
5338 // of the processing tasks (specifically phase2 - pp2_work) execute
5339 // the complete_gc closure (which ordinarily would drain the queue) so
5340 // the queue may not be empty.
5341 }
5342 };
5343
5344 // Driver routine for parallel reference processing.
5345 // Creates an instance of the ref processing gang
5346 // task and has the worker threads execute it.
5347 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5348 assert(_workers != NULL, "Need parallel worker threads.");
5349
5350 ParallelTaskTerminator terminator(_active_workers, _queues);
5351 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5352
5353 _g1h->set_par_threads(_active_workers);
5354 _workers->run_task(&proc_task_proxy);
5355 _g1h->set_par_threads(0);
5356 }
5357
5358 // Gang task for parallel reference enqueueing.
5359
5360 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5361 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5362 EnqueueTask& _enq_task;
5363
5364 public:
5365 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5366 AbstractGangTask("Enqueue reference objects in parallel"),
5367 _enq_task(enq_task)
5368 { }
5369
5370 virtual void work(uint worker_id) {
5371 _enq_task.work(worker_id);
5372 }
5373 };
5374
5375 // Driver routine for parallel reference enqueing.
5376 // Creates an instance of the ref enqueueing gang
5377 // task and has the worker threads execute it.
5378
5379 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5380 assert(_workers != NULL, "Need parallel worker threads.");
5381
5382 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5383
5384 _g1h->set_par_threads(_active_workers);
5385 _workers->run_task(&enq_task_proxy);
5386 _g1h->set_par_threads(0);
5387 }
5388
5389 // End of weak reference support closures
5390
5391 // Abstract task used to preserve (i.e. copy) any referent objects
5392 // that are in the collection set and are pointed to by reference
5393 // objects discovered by the CM ref processor.
5394
5395 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5396 protected:
5397 G1CollectedHeap* _g1h;
5398 RefToScanQueueSet *_queues;
5399 ParallelTaskTerminator _terminator;
5400 uint _n_workers;
5401
5402 public:
5403 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5404 AbstractGangTask("ParPreserveCMReferents"),
5405 _g1h(g1h),
5406 _queues(task_queues),
5407 _terminator(workers, _queues),
5408 _n_workers(workers)
5409 { }
5410
5411 void work(uint worker_id) {
5412 ResourceMark rm;
5413 HandleMark hm;
5414
5415 G1ParScanThreadState pss(_g1h, worker_id);
5416 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5417 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5418 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5419
5420 pss.set_evac_closure(&scan_evac_cl);
5421 pss.set_evac_failure_closure(&evac_failure_cl);
5422 pss.set_partial_scan_closure(&partial_scan_cl);
5423
5424 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5425
5426
5427 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5428 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5429
5430 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5431 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5432
5433 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5434 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5435
5436 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5437 // We also need to mark copied objects.
5438 copy_non_heap_cl = ©_mark_non_heap_cl;
5439 copy_metadata_cl = ©_mark_metadata_cl;
5440 }
5441
5442 // Is alive closure
5443 G1AlwaysAliveClosure always_alive(_g1h);
5444
5445 // Copying keep alive closure. Applied to referent objects that need
5446 // to be copied.
5447 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5448
5449 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5450
5451 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5452 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5453
5454 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5455 // So this must be true - but assert just in case someone decides to
5456 // change the worker ids.
5457 assert(0 <= worker_id && worker_id < limit, "sanity");
5458 assert(!rp->discovery_is_atomic(), "check this code");
5459
5460 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5461 for (uint idx = worker_id; idx < limit; idx += stride) {
5462 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5463
5464 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5465 while (iter.has_next()) {
5466 // Since discovery is not atomic for the CM ref processor, we
5467 // can see some null referent objects.
5468 iter.load_ptrs(DEBUG_ONLY(true));
5469 oop ref = iter.obj();
5470
5471 // This will filter nulls.
5472 if (iter.is_referent_alive()) {
5473 iter.make_referent_alive();
5474 }
5475 iter.move_to_next();
5476 }
5477 }
5478
5479 // Drain the queue - which may cause stealing
5480 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5481 drain_queue.do_void();
5482 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5483 assert(pss.refs()->is_empty(), "should be");
5484 }
5485 };
5486
5487 // Weak Reference processing during an evacuation pause (part 1).
5488 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5489 double ref_proc_start = os::elapsedTime();
5490
5491 ReferenceProcessor* rp = _ref_processor_stw;
5492 assert(rp->discovery_enabled(), "should have been enabled");
5493
5494 // Any reference objects, in the collection set, that were 'discovered'
5495 // by the CM ref processor should have already been copied (either by
5496 // applying the external root copy closure to the discovered lists, or
5497 // by following an RSet entry).
5498 //
5499 // But some of the referents, that are in the collection set, that these
5500 // reference objects point to may not have been copied: the STW ref
5501 // processor would have seen that the reference object had already
5502 // been 'discovered' and would have skipped discovering the reference,
5503 // but would not have treated the reference object as a regular oop.
5504 // As a reult the copy closure would not have been applied to the
5505 // referent object.
5506 //
5507 // We need to explicitly copy these referent objects - the references
5508 // will be processed at the end of remarking.
5509 //
5510 // We also need to do this copying before we process the reference
5511 // objects discovered by the STW ref processor in case one of these
5512 // referents points to another object which is also referenced by an
5513 // object discovered by the STW ref processor.
5514
5515 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5516 no_of_gc_workers == workers()->active_workers(),
5517 "Need to reset active GC workers");
5518
5519 set_par_threads(no_of_gc_workers);
5520 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5521 no_of_gc_workers,
5522 _task_queues);
5523
5524 if (G1CollectedHeap::use_parallel_gc_threads()) {
5525 workers()->run_task(&keep_cm_referents);
5526 } else {
5527 keep_cm_referents.work(0);
5528 }
5529
5530 set_par_threads(0);
5531
5532 // Closure to test whether a referent is alive.
5533 G1STWIsAliveClosure is_alive(this);
5534
5535 // Even when parallel reference processing is enabled, the processing
5536 // of JNI refs is serial and performed serially by the current thread
5537 // rather than by a worker. The following PSS will be used for processing
5538 // JNI refs.
5539
5540 // Use only a single queue for this PSS.
5541 G1ParScanThreadState pss(this, 0);
5542
5543 // We do not embed a reference processor in the copying/scanning
5544 // closures while we're actually processing the discovered
5545 // reference objects.
5546 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5547 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5548 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5549
5550 pss.set_evac_closure(&scan_evac_cl);
5551 pss.set_evac_failure_closure(&evac_failure_cl);
5552 pss.set_partial_scan_closure(&partial_scan_cl);
5553
5554 assert(pss.refs()->is_empty(), "pre-condition");
5555
5556 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5557 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5558
5559 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5560 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5561
5562 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5563 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5564
5565 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5566 // We also need to mark copied objects.
5567 copy_non_heap_cl = ©_mark_non_heap_cl;
5568 copy_metadata_cl = ©_mark_metadata_cl;
5569 }
5570
5571 // Keep alive closure.
5572 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5573
5574 // Serial Complete GC closure
5575 G1STWDrainQueueClosure drain_queue(this, &pss);
5576
5577 // Setup the soft refs policy...
5578 rp->setup_policy(false);
5579
5580 if (!rp->processing_is_mt()) {
5581 // Serial reference processing...
5582 rp->process_discovered_references(&is_alive,
5583 &keep_alive,
5584 &drain_queue,
5585 NULL);
5586 } else {
5587 // Parallel reference processing
5588 assert(rp->num_q() == no_of_gc_workers, "sanity");
5589 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5590
5591 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5592 rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5593 }
5594
5595 // We have completed copying any necessary live referent objects
5596 // (that were not copied during the actual pause) so we can
5597 // retire any active alloc buffers
5598 pss.retire_alloc_buffers();
5599 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5600
5601 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5602 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5603 }
5604
5605 // Weak Reference processing during an evacuation pause (part 2).
5606 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5607 double ref_enq_start = os::elapsedTime();
5608
5609 ReferenceProcessor* rp = _ref_processor_stw;
5610 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5611
5612 // Now enqueue any remaining on the discovered lists on to
5613 // the pending list.
5614 if (!rp->processing_is_mt()) {
5615 // Serial reference processing...
5616 rp->enqueue_discovered_references();
5617 } else {
5618 // Parallel reference enqueuing
5619
5620 assert(no_of_gc_workers == workers()->active_workers(),
5621 "Need to reset active workers");
5622 assert(rp->num_q() == no_of_gc_workers, "sanity");
5623 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5624
5625 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5626 rp->enqueue_discovered_references(&par_task_executor);
5627 }
5628
5629 rp->verify_no_references_recorded();
5630 assert(!rp->discovery_enabled(), "should have been disabled");
5631
5632 // FIXME
5633 // CM's reference processing also cleans up the string and symbol tables.
5634 // Should we do that here also? We could, but it is a serial operation
5635 // and could signicantly increase the pause time.
5636
5637 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5638 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5639 }
5640
5641 void G1CollectedHeap::evacuate_collection_set() {
5642 _expand_heap_after_alloc_failure = true;
5643 set_evacuation_failed(false);
5644
5645 // Should G1EvacuationFailureALot be in effect for this GC?
5646 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5647
5648 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5649
5650 // Disable the hot card cache.
5651 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5652 hot_card_cache->reset_hot_cache_claimed_index();
5653 hot_card_cache->set_use_cache(false);
5654
5655 uint n_workers;
5656 if (G1CollectedHeap::use_parallel_gc_threads()) {
5657 n_workers =
5658 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5659 workers()->active_workers(),
5660 Threads::number_of_non_daemon_threads());
5661 assert(UseDynamicNumberOfGCThreads ||
5662 n_workers == workers()->total_workers(),
5663 "If not dynamic should be using all the workers");
5664 workers()->set_active_workers(n_workers);
5665 set_par_threads(n_workers);
5666 } else {
5667 assert(n_par_threads() == 0,
5668 "Should be the original non-parallel value");
5669 n_workers = 1;
5670 }
5671
5672 G1ParTask g1_par_task(this, _task_queues);
5673
5674 init_for_evac_failure(NULL);
5675
5676 rem_set()->prepare_for_younger_refs_iterate(true);
5677
5678 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5679 double start_par_time_sec = os::elapsedTime();
5680 double end_par_time_sec;
5681
5682 {
5683 StrongRootsScope srs(this);
5684
5685 if (G1CollectedHeap::use_parallel_gc_threads()) {
5686 // The individual threads will set their evac-failure closures.
5687 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5688 // These tasks use ShareHeap::_process_strong_tasks
5689 assert(UseDynamicNumberOfGCThreads ||
5690 workers()->active_workers() == workers()->total_workers(),
5691 "If not dynamic should be using all the workers");
5692 workers()->run_task(&g1_par_task);
5693 } else {
5694 g1_par_task.set_for_termination(n_workers);
5695 g1_par_task.work(0);
5696 }
5697 end_par_time_sec = os::elapsedTime();
5698
5699 // Closing the inner scope will execute the destructor
5700 // for the StrongRootsScope object. We record the current
5701 // elapsed time before closing the scope so that time
5702 // taken for the SRS destructor is NOT included in the
5703 // reported parallel time.
5704 }
5705
5706 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5707 g1_policy()->phase_times()->record_par_time(par_time_ms);
5708
5709 double code_root_fixup_time_ms =
5710 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5711 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5712
5713 set_par_threads(0);
5714
5715 // Process any discovered reference objects - we have
5716 // to do this _before_ we retire the GC alloc regions
5717 // as we may have to copy some 'reachable' referent
5718 // objects (and their reachable sub-graphs) that were
5719 // not copied during the pause.
5720 process_discovered_references(n_workers);
5721
5722 // Weak root processing.
5723 {
5724 G1STWIsAliveClosure is_alive(this);
5725 G1KeepAliveClosure keep_alive(this);
5726 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5727 }
5728
5729 release_gc_alloc_regions(n_workers);
5730 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5731
5732 // Reset and re-enable the hot card cache.
5733 // Note the counts for the cards in the regions in the
5734 // collection set are reset when the collection set is freed.
5735 hot_card_cache->reset_hot_cache();
5736 hot_card_cache->set_use_cache(true);
5737
5738 // Migrate the strong code roots attached to each region in
5739 // the collection set. Ideally we would like to do this
5740 // after we have finished the scanning/evacuation of the
5741 // strong code roots for a particular heap region.
5742 migrate_strong_code_roots();
5743
5744 if (g1_policy()->during_initial_mark_pause()) {
5745 // Reset the claim values set during marking the strong code roots
5746 reset_heap_region_claim_values();
5747 }
5748
5749 finalize_for_evac_failure();
5750
5751 if (evacuation_failed()) {
5752 remove_self_forwarding_pointers();
5753
5754 // Reset the G1EvacuationFailureALot counters and flags
5755 // Note: the values are reset only when an actual
5756 // evacuation failure occurs.
5757 NOT_PRODUCT(reset_evacuation_should_fail();)
5758 }
5759
5760 // Enqueue any remaining references remaining on the STW
5761 // reference processor's discovered lists. We need to do
5762 // this after the card table is cleaned (and verified) as
5763 // the act of enqueuing entries on to the pending list
5764 // will log these updates (and dirty their associated
5765 // cards). We need these updates logged to update any
5766 // RSets.
5767 enqueue_discovered_references(n_workers);
5768
5769 if (G1DeferredRSUpdate) {
5770 RedirtyLoggedCardTableEntryFastClosure redirty;
5771 dirty_card_queue_set().set_closure(&redirty);
5772 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5773
5774 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5775 dcq.merge_bufferlists(&dirty_card_queue_set());
5776 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5777 }
5778 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5779 }
5780
5781 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5782 size_t* pre_used,
5783 FreeRegionList* free_list,
5784 OldRegionSet* old_proxy_set,
5785 HumongousRegionSet* humongous_proxy_set,
5786 HRRSCleanupTask* hrrs_cleanup_task,
5787 bool par) {
5788 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5789 if (hr->isHumongous()) {
5790 assert(hr->startsHumongous(), "we should only see starts humongous");
5791 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5792 } else {
5793 _old_set.remove_with_proxy(hr, old_proxy_set);
5794 free_region(hr, pre_used, free_list, par);
5795 }
5796 } else {
5797 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5798 }
5799 }
5800
5801 void G1CollectedHeap::free_region(HeapRegion* hr,
5802 size_t* pre_used,
5803 FreeRegionList* free_list,
5804 bool par) {
5805 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5806 assert(!hr->is_empty(), "the region should not be empty");
5807 assert(free_list != NULL, "pre-condition");
5808
5809 // Clear the card counts for this region.
5810 // Note: we only need to do this if the region is not young
5811 // (since we don't refine cards in young regions).
5812 if (!hr->is_young()) {
5813 _cg1r->hot_card_cache()->reset_card_counts(hr);
5814 }
5815 *pre_used += hr->used();
5816 hr->hr_clear(par, true /* clear_space */);
5817 free_list->add_as_head(hr);
5818 }
5819
5820 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5821 size_t* pre_used,
5822 FreeRegionList* free_list,
5823 HumongousRegionSet* humongous_proxy_set,
5824 bool par) {
5825 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5826 assert(free_list != NULL, "pre-condition");
5827 assert(humongous_proxy_set != NULL, "pre-condition");
5828
5829 size_t hr_used = hr->used();
5830 size_t hr_capacity = hr->capacity();
5831 size_t hr_pre_used = 0;
5832 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5833 // We need to read this before we make the region non-humongous,
5834 // otherwise the information will be gone.
5835 uint last_index = hr->last_hc_index();
5836 hr->set_notHumongous();
5837 free_region(hr, &hr_pre_used, free_list, par);
5838
5839 uint i = hr->hrs_index() + 1;
5840 while (i < last_index) {
5841 HeapRegion* curr_hr = region_at(i);
5842 assert(curr_hr->continuesHumongous(), "invariant");
5843 curr_hr->set_notHumongous();
5844 free_region(curr_hr, &hr_pre_used, free_list, par);
5845 i += 1;
5846 }
5847 assert(hr_pre_used == hr_used,
5848 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5849 "should be the same", hr_pre_used, hr_used));
5850 *pre_used += hr_pre_used;
5851 }
5852
5853 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5854 FreeRegionList* free_list,
5855 OldRegionSet* old_proxy_set,
5856 HumongousRegionSet* humongous_proxy_set,
5857 bool par) {
5858 if (pre_used > 0) {
5859 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5860 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5861 assert(_summary_bytes_used >= pre_used,
5862 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5863 "should be >= pre_used: "SIZE_FORMAT,
5864 _summary_bytes_used, pre_used));
5865 _summary_bytes_used -= pre_used;
5866 }
5867 if (free_list != NULL && !free_list->is_empty()) {
5868 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5869 _free_list.add_as_head(free_list);
5870 }
5871 if (old_proxy_set != NULL && !old_proxy_set->is_empty()) {
5872 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5873 _old_set.update_from_proxy(old_proxy_set);
5874 }
5875 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5876 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5877 _humongous_set.update_from_proxy(humongous_proxy_set);
5878 }
5879 }
5880
5881 class G1ParCleanupCTTask : public AbstractGangTask {
5882 CardTableModRefBS* _ct_bs;
5883 G1CollectedHeap* _g1h;
5884 HeapRegion* volatile _su_head;
5885 public:
5886 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5887 G1CollectedHeap* g1h) :
5888 AbstractGangTask("G1 Par Cleanup CT Task"),
5889 _ct_bs(ct_bs), _g1h(g1h) { }
5890
5891 void work(uint worker_id) {
5892 HeapRegion* r;
5893 while (r = _g1h->pop_dirty_cards_region()) {
5894 clear_cards(r);
5895 }
5896 }
5897
5898 void clear_cards(HeapRegion* r) {
5899 // Cards of the survivors should have already been dirtied.
5900 if (!r->is_survivor()) {
5901 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5902 }
5903 }
5904 };
5905
5906 #ifndef PRODUCT
5907 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5908 G1CollectedHeap* _g1h;
5909 CardTableModRefBS* _ct_bs;
5910 public:
5911 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5912 : _g1h(g1h), _ct_bs(ct_bs) { }
5913 virtual bool doHeapRegion(HeapRegion* r) {
5914 if (r->is_survivor()) {
5915 _g1h->verify_dirty_region(r);
5916 } else {
5917 _g1h->verify_not_dirty_region(r);
5918 }
5919 return false;
5920 }
5921 };
5922
5923 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5924 // All of the region should be clean.
5925 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5926 MemRegion mr(hr->bottom(), hr->end());
5927 ct_bs->verify_not_dirty_region(mr);
5928 }
5929
5930 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5931 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5932 // dirty allocated blocks as they allocate them. The thread that
5933 // retires each region and replaces it with a new one will do a
5934 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5935 // not dirty that area (one less thing to have to do while holding
5936 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5937 // is dirty.
5938 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5939 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5940 ct_bs->verify_dirty_region(mr);
5941 }
5942
5943 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5944 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5945 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5946 verify_dirty_region(hr);
5947 }
5948 }
5949
5950 void G1CollectedHeap::verify_dirty_young_regions() {
5951 verify_dirty_young_list(_young_list->first_region());
5952 }
5953 #endif
5954
5955 void G1CollectedHeap::cleanUpCardTable() {
5956 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5957 double start = os::elapsedTime();
5958
5959 {
5960 // Iterate over the dirty cards region list.
5961 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5962
5963 if (G1CollectedHeap::use_parallel_gc_threads()) {
5964 set_par_threads();
5965 workers()->run_task(&cleanup_task);
5966 set_par_threads(0);
5967 } else {
5968 while (_dirty_cards_region_list) {
5969 HeapRegion* r = _dirty_cards_region_list;
5970 cleanup_task.clear_cards(r);
5971 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5972 if (_dirty_cards_region_list == r) {
5973 // The last region.
5974 _dirty_cards_region_list = NULL;
5975 }
5976 r->set_next_dirty_cards_region(NULL);
5977 }
5978 }
5979 #ifndef PRODUCT
5980 if (G1VerifyCTCleanup || VerifyAfterGC) {
5981 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5982 heap_region_iterate(&cleanup_verifier);
5983 }
5984 #endif
5985 }
5986
5987 double elapsed = os::elapsedTime() - start;
5988 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5989 }
5990
5991 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5992 size_t pre_used = 0;
5993 FreeRegionList local_free_list("Local List for CSet Freeing");
5994
5995 double young_time_ms = 0.0;
5996 double non_young_time_ms = 0.0;
5997
5998 // Since the collection set is a superset of the the young list,
5999 // all we need to do to clear the young list is clear its
6000 // head and length, and unlink any young regions in the code below
6001 _young_list->clear();
6002
6003 G1CollectorPolicy* policy = g1_policy();
6004
6005 double start_sec = os::elapsedTime();
6006 bool non_young = true;
6007
6008 HeapRegion* cur = cs_head;
6009 int age_bound = -1;
6010 size_t rs_lengths = 0;
6011
6012 while (cur != NULL) {
6013 assert(!is_on_master_free_list(cur), "sanity");
6014 if (non_young) {
6015 if (cur->is_young()) {
6016 double end_sec = os::elapsedTime();
6017 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6018 non_young_time_ms += elapsed_ms;
6019
6020 start_sec = os::elapsedTime();
6021 non_young = false;
6022 }
6023 } else {
6024 if (!cur->is_young()) {
6025 double end_sec = os::elapsedTime();
6026 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6027 young_time_ms += elapsed_ms;
6028
6029 start_sec = os::elapsedTime();
6030 non_young = true;
6031 }
6032 }
6033
6034 rs_lengths += cur->rem_set()->occupied();
6035
6036 HeapRegion* next = cur->next_in_collection_set();
6037 assert(cur->in_collection_set(), "bad CS");
6038 cur->set_next_in_collection_set(NULL);
6039 cur->set_in_collection_set(false);
6040
6041 if (cur->is_young()) {
6042 int index = cur->young_index_in_cset();
6043 assert(index != -1, "invariant");
6044 assert((uint) index < policy->young_cset_region_length(), "invariant");
6045 size_t words_survived = _surviving_young_words[index];
6046 cur->record_surv_words_in_group(words_survived);
6047
6048 // At this point the we have 'popped' cur from the collection set
6049 // (linked via next_in_collection_set()) but it is still in the
6050 // young list (linked via next_young_region()). Clear the
6051 // _next_young_region field.
6052 cur->set_next_young_region(NULL);
6053 } else {
6054 int index = cur->young_index_in_cset();
6055 assert(index == -1, "invariant");
6056 }
6057
6058 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6059 (!cur->is_young() && cur->young_index_in_cset() == -1),
6060 "invariant" );
6061
6062 if (!cur->evacuation_failed()) {
6063 MemRegion used_mr = cur->used_region();
6064
6065 // And the region is empty.
6066 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6067 free_region(cur, &pre_used, &local_free_list, false /* par */);
6068 } else {
6069 cur->uninstall_surv_rate_group();
6070 if (cur->is_young()) {
6071 cur->set_young_index_in_cset(-1);
6072 }
6073 cur->set_not_young();
6074 cur->set_evacuation_failed(false);
6075 // The region is now considered to be old.
6076 _old_set.add(cur);
6077 }
6078 cur = next;
6079 }
6080
6081 policy->record_max_rs_lengths(rs_lengths);
6082 policy->cset_regions_freed();
6083
6084 double end_sec = os::elapsedTime();
6085 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6086
6087 if (non_young) {
6088 non_young_time_ms += elapsed_ms;
6089 } else {
6090 young_time_ms += elapsed_ms;
6091 }
6092
6093 update_sets_after_freeing_regions(pre_used, &local_free_list,
6094 NULL /* old_proxy_set */,
6095 NULL /* humongous_proxy_set */,
6096 false /* par */);
6097 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6098 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6099 }
6100
6101 // This routine is similar to the above but does not record
6102 // any policy statistics or update free lists; we are abandoning
6103 // the current incremental collection set in preparation of a
6104 // full collection. After the full GC we will start to build up
6105 // the incremental collection set again.
6106 // This is only called when we're doing a full collection
6107 // and is immediately followed by the tearing down of the young list.
6108
6109 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6110 HeapRegion* cur = cs_head;
6111
6112 while (cur != NULL) {
6113 HeapRegion* next = cur->next_in_collection_set();
6114 assert(cur->in_collection_set(), "bad CS");
6115 cur->set_next_in_collection_set(NULL);
6116 cur->set_in_collection_set(false);
6117 cur->set_young_index_in_cset(-1);
6118 cur = next;
6119 }
6120 }
6121
6122 void G1CollectedHeap::set_free_regions_coming() {
6123 if (G1ConcRegionFreeingVerbose) {
6124 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6125 "setting free regions coming");
6126 }
6127
6128 assert(!free_regions_coming(), "pre-condition");
6129 _free_regions_coming = true;
6130 }
6131
6132 void G1CollectedHeap::reset_free_regions_coming() {
6133 assert(free_regions_coming(), "pre-condition");
6134
6135 {
6136 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6137 _free_regions_coming = false;
6138 SecondaryFreeList_lock->notify_all();
6139 }
6140
6141 if (G1ConcRegionFreeingVerbose) {
6142 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6143 "reset free regions coming");
6144 }
6145 }
6146
6147 void G1CollectedHeap::wait_while_free_regions_coming() {
6148 // Most of the time we won't have to wait, so let's do a quick test
6149 // first before we take the lock.
6150 if (!free_regions_coming()) {
6151 return;
6152 }
6153
6154 if (G1ConcRegionFreeingVerbose) {
6155 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6156 "waiting for free regions");
6157 }
6158
6159 {
6160 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6161 while (free_regions_coming()) {
6162 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6163 }
6164 }
6165
6166 if (G1ConcRegionFreeingVerbose) {
6167 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6168 "done waiting for free regions");
6169 }
6170 }
6171
6172 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6173 assert(heap_lock_held_for_gc(),
6174 "the heap lock should already be held by or for this thread");
6175 _young_list->push_region(hr);
6176 }
6177
6178 class NoYoungRegionsClosure: public HeapRegionClosure {
6179 private:
6180 bool _success;
6181 public:
6182 NoYoungRegionsClosure() : _success(true) { }
6183 bool doHeapRegion(HeapRegion* r) {
6184 if (r->is_young()) {
6185 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6186 r->bottom(), r->end());
6187 _success = false;
6188 }
6189 return false;
6190 }
6191 bool success() { return _success; }
6192 };
6193
6194 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6195 bool ret = _young_list->check_list_empty(check_sample);
6196
6197 if (check_heap) {
6198 NoYoungRegionsClosure closure;
6199 heap_region_iterate(&closure);
6200 ret = ret && closure.success();
6201 }
6202
6203 return ret;
6204 }
6205
6206 class TearDownRegionSetsClosure : public HeapRegionClosure {
6207 private:
6208 OldRegionSet *_old_set;
6209
6210 public:
6211 TearDownRegionSetsClosure(OldRegionSet* old_set) : _old_set(old_set) { }
6212
6213 bool doHeapRegion(HeapRegion* r) {
6214 if (r->is_empty()) {
6215 // We ignore empty regions, we'll empty the free list afterwards
6216 } else if (r->is_young()) {
6217 // We ignore young regions, we'll empty the young list afterwards
6218 } else if (r->isHumongous()) {
6219 // We ignore humongous regions, we're not tearing down the
6220 // humongous region set
6221 } else {
6222 // The rest should be old
6223 _old_set->remove(r);
6224 }
6225 return false;
6226 }
6227
6228 ~TearDownRegionSetsClosure() {
6229 assert(_old_set->is_empty(), "post-condition");
6230 }
6231 };
6232
6233 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6234 assert_at_safepoint(true /* should_be_vm_thread */);
6235
6236 if (!free_list_only) {
6237 TearDownRegionSetsClosure cl(&_old_set);
6238 heap_region_iterate(&cl);
6239
6240 // Need to do this after the heap iteration to be able to
6241 // recognize the young regions and ignore them during the iteration.
6242 _young_list->empty_list();
6243 }
6244 _free_list.remove_all();
6245 }
6246
6247 class RebuildRegionSetsClosure : public HeapRegionClosure {
6248 private:
6249 bool _free_list_only;
6250 OldRegionSet* _old_set;
6251 FreeRegionList* _free_list;
6252 size_t _total_used;
6253
6254 public:
6255 RebuildRegionSetsClosure(bool free_list_only,
6256 OldRegionSet* old_set, FreeRegionList* free_list) :
6257 _free_list_only(free_list_only),
6258 _old_set(old_set), _free_list(free_list), _total_used(0) {
6259 assert(_free_list->is_empty(), "pre-condition");
6260 if (!free_list_only) {
6261 assert(_old_set->is_empty(), "pre-condition");
6262 }
6263 }
6264
6265 bool doHeapRegion(HeapRegion* r) {
6266 if (r->continuesHumongous()) {
6267 return false;
6268 }
6269
6270 if (r->is_empty()) {
6271 // Add free regions to the free list
6272 _free_list->add_as_tail(r);
6273 } else if (!_free_list_only) {
6274 assert(!r->is_young(), "we should not come across young regions");
6275
6276 if (r->isHumongous()) {
6277 // We ignore humongous regions, we left the humongous set unchanged
6278 } else {
6279 // The rest should be old, add them to the old set
6280 _old_set->add(r);
6281 }
6282 _total_used += r->used();
6283 }
6284
6285 return false;
6286 }
6287
6288 size_t total_used() {
6289 return _total_used;
6290 }
6291 };
6292
6293 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6294 assert_at_safepoint(true /* should_be_vm_thread */);
6295
6296 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6297 heap_region_iterate(&cl);
6298
6299 if (!free_list_only) {
6300 _summary_bytes_used = cl.total_used();
6301 }
6302 assert(_summary_bytes_used == recalculate_used(),
6303 err_msg("inconsistent _summary_bytes_used, "
6304 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6305 _summary_bytes_used, recalculate_used()));
6306 }
6307
6308 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6309 _refine_cte_cl->set_concurrent(concurrent);
6310 }
6311
6312 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6313 HeapRegion* hr = heap_region_containing(p);
6314 if (hr == NULL) {
6315 return false;
6316 } else {
6317 return hr->is_in(p);
6318 }
6319 }
6320
6321 // Methods for the mutator alloc region
6322
6323 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6324 bool force) {
6325 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6326 assert(!force || g1_policy()->can_expand_young_list(),
6327 "if force is true we should be able to expand the young list");
6328 bool young_list_full = g1_policy()->is_young_list_full();
6329 if (force || !young_list_full) {
6330 HeapRegion* new_alloc_region = new_region(word_size,
6331 false /* do_expand */);
6332 if (new_alloc_region != NULL) {
6333 set_region_short_lived_locked(new_alloc_region);
6334 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6335 return new_alloc_region;
6336 }
6337 }
6338 return NULL;
6339 }
6340
6341 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6342 size_t allocated_bytes) {
6343 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6344 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6345
6346 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6347 _summary_bytes_used += allocated_bytes;
6348 _hr_printer.retire(alloc_region);
6349 // We update the eden sizes here, when the region is retired,
6350 // instead of when it's allocated, since this is the point that its
6351 // used space has been recored in _summary_bytes_used.
6352 g1mm()->update_eden_size();
6353 }
6354
6355 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6356 bool force) {
6357 return _g1h->new_mutator_alloc_region(word_size, force);
6358 }
6359
6360 void G1CollectedHeap::set_par_threads() {
6361 // Don't change the number of workers. Use the value previously set
6362 // in the workgroup.
6363 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6364 uint n_workers = workers()->active_workers();
6365 assert(UseDynamicNumberOfGCThreads ||
6366 n_workers == workers()->total_workers(),
6367 "Otherwise should be using the total number of workers");
6368 if (n_workers == 0) {
6369 assert(false, "Should have been set in prior evacuation pause.");
6370 n_workers = ParallelGCThreads;
6371 workers()->set_active_workers(n_workers);
6372 }
6373 set_par_threads(n_workers);
6374 }
6375
6376 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6377 size_t allocated_bytes) {
6378 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6379 }
6380
6381 // Methods for the GC alloc regions
6382
6383 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6384 uint count,
6385 GCAllocPurpose ap) {
6386 assert(FreeList_lock->owned_by_self(), "pre-condition");
6387
6388 if (count < g1_policy()->max_regions(ap)) {
6389 HeapRegion* new_alloc_region = new_region(word_size,
6390 true /* do_expand */);
6391 if (new_alloc_region != NULL) {
6392 // We really only need to do this for old regions given that we
6393 // should never scan survivors. But it doesn't hurt to do it
6394 // for survivors too.
6395 new_alloc_region->set_saved_mark();
6396 if (ap == GCAllocForSurvived) {
6397 new_alloc_region->set_survivor();
6398 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6399 } else {
6400 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6401 }
6402 bool during_im = g1_policy()->during_initial_mark_pause();
6403 new_alloc_region->note_start_of_copying(during_im);
6404 return new_alloc_region;
6405 } else {
6406 g1_policy()->note_alloc_region_limit_reached(ap);
6407 }
6408 }
6409 return NULL;
6410 }
6411
6412 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6413 size_t allocated_bytes,
6414 GCAllocPurpose ap) {
6415 bool during_im = g1_policy()->during_initial_mark_pause();
6416 alloc_region->note_end_of_copying(during_im);
6417 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6418 if (ap == GCAllocForSurvived) {
6419 young_list()->add_survivor_region(alloc_region);
6420 } else {
6421 _old_set.add(alloc_region);
6422 }
6423 _hr_printer.retire(alloc_region);
6424 }
6425
6426 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6427 bool force) {
6428 assert(!force, "not supported for GC alloc regions");
6429 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6430 }
6431
6432 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6433 size_t allocated_bytes) {
6434 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6435 GCAllocForSurvived);
6436 }
6437
6438 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6439 bool force) {
6440 assert(!force, "not supported for GC alloc regions");
6441 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6442 }
6443
6444 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6445 size_t allocated_bytes) {
6446 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6447 GCAllocForTenured);
6448 }
6449 // Heap region set verification
6450
6451 class VerifyRegionListsClosure : public HeapRegionClosure {
6452 private:
6453 FreeRegionList* _free_list;
6454 OldRegionSet* _old_set;
6455 HumongousRegionSet* _humongous_set;
6456 uint _region_count;
6457
6458 public:
6459 VerifyRegionListsClosure(OldRegionSet* old_set,
6460 HumongousRegionSet* humongous_set,
6461 FreeRegionList* free_list) :
6462 _old_set(old_set), _humongous_set(humongous_set),
6463 _free_list(free_list), _region_count(0) { }
6464
6465 uint region_count() { return _region_count; }
6466
6467 bool doHeapRegion(HeapRegion* hr) {
6468 _region_count += 1;
6469
6470 if (hr->continuesHumongous()) {
6471 return false;
6472 }
6473
6474 if (hr->is_young()) {
6475 // TODO
6476 } else if (hr->startsHumongous()) {
6477 _humongous_set->verify_next_region(hr);
6478 } else if (hr->is_empty()) {
6479 _free_list->verify_next_region(hr);
6480 } else {
6481 _old_set->verify_next_region(hr);
6482 }
6483 return false;
6484 }
6485 };
6486
6487 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6488 HeapWord* bottom) {
6489 HeapWord* end = bottom + HeapRegion::GrainWords;
6490 MemRegion mr(bottom, end);
6491 assert(_g1_reserved.contains(mr), "invariant");
6492 // This might return NULL if the allocation fails
6493 return new HeapRegion(hrs_index, _bot_shared, mr);
6494 }
6495
6496 void G1CollectedHeap::verify_region_sets() {
6497 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6498
6499 // First, check the explicit lists.
6500 _free_list.verify();
6501 {
6502 // Given that a concurrent operation might be adding regions to
6503 // the secondary free list we have to take the lock before
6504 // verifying it.
6505 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6506 _secondary_free_list.verify();
6507 }
6508 _old_set.verify();
6509 _humongous_set.verify();
6510
6511 // If a concurrent region freeing operation is in progress it will
6512 // be difficult to correctly attributed any free regions we come
6513 // across to the correct free list given that they might belong to
6514 // one of several (free_list, secondary_free_list, any local lists,
6515 // etc.). So, if that's the case we will skip the rest of the
6516 // verification operation. Alternatively, waiting for the concurrent
6517 // operation to complete will have a non-trivial effect on the GC's
6518 // operation (no concurrent operation will last longer than the
6519 // interval between two calls to verification) and it might hide
6520 // any issues that we would like to catch during testing.
6521 if (free_regions_coming()) {
6522 return;
6523 }
6524
6525 // Make sure we append the secondary_free_list on the free_list so
6526 // that all free regions we will come across can be safely
6527 // attributed to the free_list.
6528 append_secondary_free_list_if_not_empty_with_lock();
6529
6530 // Finally, make sure that the region accounting in the lists is
6531 // consistent with what we see in the heap.
6532 _old_set.verify_start();
6533 _humongous_set.verify_start();
6534 _free_list.verify_start();
6535
6536 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6537 heap_region_iterate(&cl);
6538
6539 _old_set.verify_end();
6540 _humongous_set.verify_end();
6541 _free_list.verify_end();
6542 }
6543
6544 // Optimized nmethod scanning
6545
6546 class RegisterNMethodOopClosure: public OopClosure {
6547 G1CollectedHeap* _g1h;
6548 nmethod* _nm;
6549
6550 template <class T> void do_oop_work(T* p) {
6551 T heap_oop = oopDesc::load_heap_oop(p);
6552 if (!oopDesc::is_null(heap_oop)) {
6553 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6554 HeapRegion* hr = _g1h->heap_region_containing(obj);
6555 assert(!hr->isHumongous(), "code root in humongous region?");
6556
6557 // HeapRegion::add_strong_code_root() avoids adding duplicate
6558 // entries but having duplicates is OK since we "mark" nmethods
6559 // as visited when we scan the strong code root lists during the GC.
6560 hr->add_strong_code_root(_nm);
6561 assert(hr->rem_set()->strong_code_roots_list_contains(_nm), "add failed?");
6562 }
6563 }
6564
6565 public:
6566 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6567 _g1h(g1h), _nm(nm) {}
6568
6569 void do_oop(oop* p) { do_oop_work(p); }
6570 void do_oop(narrowOop* p) { do_oop_work(p); }
6571 };
6572
6573 class UnregisterNMethodOopClosure: public OopClosure {
6574 G1CollectedHeap* _g1h;
6575 nmethod* _nm;
6576
6577 template <class T> void do_oop_work(T* p) {
6578 T heap_oop = oopDesc::load_heap_oop(p);
6579 if (!oopDesc::is_null(heap_oop)) {
6580 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6581 HeapRegion* hr = _g1h->heap_region_containing(obj);
6582 assert(!hr->isHumongous(), "code root in humongous region?");
6583 hr->remove_strong_code_root(_nm);
6584 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm), "remove failed?");
6585 }
6586 }
6587
6588 public:
6589 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6590 _g1h(g1h), _nm(nm) {}
6591
6592 void do_oop(oop* p) { do_oop_work(p); }
6593 void do_oop(narrowOop* p) { do_oop_work(p); }
6594 };
6595
6596 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6597 guarantee(nm != NULL, "sanity");
6598 RegisterNMethodOopClosure reg_cl(this, nm);
6599 nm->oops_do(®_cl);
6600 }
6601
6602 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6603 guarantee(nm != NULL, "sanity");
6604 UnregisterNMethodOopClosure reg_cl(this, nm);
6605 nm->oops_do(®_cl);
6606 }
6607
6608 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6609 public:
6610 bool doHeapRegion(HeapRegion *hr) {
6611 assert(!hr->isHumongous(), "humongous region in collection set?");
6612 hr->migrate_strong_code_roots();
6613 return false;
6614 }
6615 };
6616
6617 void G1CollectedHeap::migrate_strong_code_roots() {
6618 MigrateCodeRootsHeapRegionClosure cl;
6619 double migrate_start = os::elapsedTime();
6620 collection_set_iterate(&cl);
6621 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6622 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6623 }
6624
6625 // Mark all the code roots that point into regions *not* in the
6626 // collection set.
6627 //
6628 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6629 // walking the the code roots lists of regions not in the collection
6630 // set. Suppose we have an nmethod (M) that points to objects in two
6631 // separate regions - one in the collection set (R1) and one not (R2).
6632 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6633 // nmethod M when walking the code roots for R1. When we come to scan
6634 // the code roots for R2, we would see that M is already marked and it
6635 // would be skipped and the objects in R2 that are referenced from M
6636 // would not be evacuated.
6637
6638 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6639
6640 class MarkStrongCodeRootOopClosure: public OopClosure {
6641 ConcurrentMark* _cm;
6642 HeapRegion* _hr;
6643 uint _worker_id;
6644
6645 template <class T> void do_oop_work(T* p) {
6646 T heap_oop = oopDesc::load_heap_oop(p);
6647 if (!oopDesc::is_null(heap_oop)) {
6648 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6649 // Only mark objects in the region (which is assumed
6650 // to be not in the collection set).
6651 if (_hr->is_in(obj)) {
6652 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6653 }
6654 }
6655 }
6656
6657 public:
6658 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6659 _cm(cm), _hr(hr), _worker_id(worker_id) {
6660 assert(!_hr->in_collection_set(), "sanity");
6661 }
6662
6663 void do_oop(narrowOop* p) { do_oop_work(p); }
6664 void do_oop(oop* p) { do_oop_work(p); }
6665 };
6666
6667 MarkStrongCodeRootOopClosure _oop_cl;
6668
6669 public:
6670 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6671 _oop_cl(cm, hr, worker_id) {}
6672
6673 void do_code_blob(CodeBlob* cb) {
6674 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6675 if (nm != NULL) {
6676 nm->oops_do(&_oop_cl);
6677 }
6678 }
6679 };
6680
6681 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6682 G1CollectedHeap* _g1h;
6683 uint _worker_id;
6684
6685 public:
6686 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6687 _g1h(g1h), _worker_id(worker_id) {}
6688
6689 bool doHeapRegion(HeapRegion *hr) {
6690 HeapRegionRemSet* hrrs = hr->rem_set();
6691 if (hr->isHumongous()) {
6692 // Code roots should never be attached to a humongous region
6693 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
6694 return false;
6695 }
6696
6697 if (hr->in_collection_set()) {
6698 // Don't mark code roots into regions in the collection set here.
6699 // They will be marked when we scan them.
6700 return false;
6701 }
6702
6703 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6704 hr->strong_code_roots_do(&cb_cl);
6705 return false;
6706 }
6707 };
6708
6709 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6710 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6711 heap_region_par_iterate_chunked(&cl,
6712 worker_id,
6713 workers()->active_workers(),
6714 HeapRegion::ParMarkRootClaimValue);
6715 }
6716
6717 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6718 G1CollectedHeap* _g1h;
6719
6720 public:
6721 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6722 _g1h(g1h) {}
6723
6724 void do_code_blob(CodeBlob* cb) {
6725 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6726 if (nm == NULL) {
6727 return;
6728 }
6729
6730 if (ScavengeRootsInCode && nm->detect_scavenge_root_oops()) {
6731 _g1h->register_nmethod(nm);
6732 }
6733 }
6734 };
6735
6736 void G1CollectedHeap::rebuild_strong_code_roots() {
6737 RebuildStrongCodeRootClosure blob_cl(this);
6738 CodeCache::blobs_do(&blob_cl);
6739 }