1 /*
2 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "code/icBuffer.hpp"
27 #include "gc_implementation/g1/bufferingOopClosure.hpp"
28 #include "gc_implementation/g1/concurrentG1Refine.hpp"
29 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
30 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
31 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
32 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
33 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
34 #include "gc_implementation/g1/g1MarkSweep.hpp"
35 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
36 #include "gc_implementation/g1/g1RemSet.inline.hpp"
37 #include "gc_implementation/g1/heapRegionRemSet.hpp"
38 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
39 #include "gc_implementation/g1/vm_operations_g1.hpp"
40 #include "gc_implementation/shared/isGCActiveMark.hpp"
41 #include "memory/gcLocker.inline.hpp"
42 #include "memory/genOopClosures.inline.hpp"
43 #include "memory/generationSpec.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/oop.pcgc.inline.hpp"
46 #include "runtime/aprofiler.hpp"
47 #include "runtime/vmThread.hpp"
48
49 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
50
51 // turn it on so that the contents of the young list (scan-only /
52 // to-be-collected) are printed at "strategic" points before / during
53 // / after the collection --- this is useful for debugging
54 #define YOUNG_LIST_VERBOSE 0
55 // CURRENT STATUS
56 // This file is under construction. Search for "FIXME".
57
58 // INVARIANTS/NOTES
59 //
60 // All allocation activity covered by the G1CollectedHeap interface is
61 // serialized by acquiring the HeapLock. This happens in mem_allocate
62 // and allocate_new_tlab, which are the "entry" points to the
63 // allocation code from the rest of the JVM. (Note that this does not
64 // apply to TLAB allocation, which is not part of this interface: it
65 // is done by clients of this interface.)
66
67 // Local to this file.
68
69 class RefineCardTableEntryClosure: public CardTableEntryClosure {
70 SuspendibleThreadSet* _sts;
71 G1RemSet* _g1rs;
72 ConcurrentG1Refine* _cg1r;
73 bool _concurrent;
74 public:
75 RefineCardTableEntryClosure(SuspendibleThreadSet* sts,
76 G1RemSet* g1rs,
77 ConcurrentG1Refine* cg1r) :
78 _sts(sts), _g1rs(g1rs), _cg1r(cg1r), _concurrent(true)
79 {}
80 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
81 bool oops_into_cset = _g1rs->concurrentRefineOneCard(card_ptr, worker_i, false);
82 // This path is executed by the concurrent refine or mutator threads,
83 // concurrently, and so we do not care if card_ptr contains references
84 // that point into the collection set.
85 assert(!oops_into_cset, "should be");
86
87 if (_concurrent && _sts->should_yield()) {
88 // Caller will actually yield.
89 return false;
90 }
91 // Otherwise, we finished successfully; return true.
92 return true;
93 }
94 void set_concurrent(bool b) { _concurrent = b; }
95 };
96
97
98 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
99 int _calls;
100 G1CollectedHeap* _g1h;
101 CardTableModRefBS* _ctbs;
102 int _histo[256];
103 public:
104 ClearLoggedCardTableEntryClosure() :
105 _calls(0)
106 {
107 _g1h = G1CollectedHeap::heap();
108 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
109 for (int i = 0; i < 256; i++) _histo[i] = 0;
110 }
111 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
112 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
113 _calls++;
114 unsigned char* ujb = (unsigned char*)card_ptr;
115 int ind = (int)(*ujb);
116 _histo[ind]++;
117 *card_ptr = -1;
118 }
119 return true;
120 }
121 int calls() { return _calls; }
122 void print_histo() {
123 gclog_or_tty->print_cr("Card table value histogram:");
124 for (int i = 0; i < 256; i++) {
125 if (_histo[i] != 0) {
126 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
127 }
128 }
129 }
130 };
131
132 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
133 int _calls;
134 G1CollectedHeap* _g1h;
135 CardTableModRefBS* _ctbs;
136 public:
137 RedirtyLoggedCardTableEntryClosure() :
138 _calls(0)
139 {
140 _g1h = G1CollectedHeap::heap();
141 _ctbs = (CardTableModRefBS*)_g1h->barrier_set();
142 }
143 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
144 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
145 _calls++;
146 *card_ptr = 0;
147 }
148 return true;
149 }
150 int calls() { return _calls; }
151 };
152
153 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
154 public:
155 bool do_card_ptr(jbyte* card_ptr, int worker_i) {
156 *card_ptr = CardTableModRefBS::dirty_card_val();
157 return true;
158 }
159 };
160
161 YoungList::YoungList(G1CollectedHeap* g1h)
162 : _g1h(g1h), _head(NULL),
163 _length(0),
164 _last_sampled_rs_lengths(0),
165 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0)
166 {
167 guarantee( check_list_empty(false), "just making sure..." );
168 }
169
170 void YoungList::push_region(HeapRegion *hr) {
171 assert(!hr->is_young(), "should not already be young");
172 assert(hr->get_next_young_region() == NULL, "cause it should!");
173
174 hr->set_next_young_region(_head);
175 _head = hr;
176
177 hr->set_young();
178 double yg_surv_rate = _g1h->g1_policy()->predict_yg_surv_rate((int)_length);
179 ++_length;
180 }
181
182 void YoungList::add_survivor_region(HeapRegion* hr) {
183 assert(hr->is_survivor(), "should be flagged as survivor region");
184 assert(hr->get_next_young_region() == NULL, "cause it should!");
185
186 hr->set_next_young_region(_survivor_head);
187 if (_survivor_head == NULL) {
188 _survivor_tail = hr;
189 }
190 _survivor_head = hr;
191
192 ++_survivor_length;
193 }
194
195 void YoungList::empty_list(HeapRegion* list) {
196 while (list != NULL) {
197 HeapRegion* next = list->get_next_young_region();
198 list->set_next_young_region(NULL);
199 list->uninstall_surv_rate_group();
200 list->set_not_young();
201 list = next;
202 }
203 }
204
205 void YoungList::empty_list() {
206 assert(check_list_well_formed(), "young list should be well formed");
207
208 empty_list(_head);
209 _head = NULL;
210 _length = 0;
211
212 empty_list(_survivor_head);
213 _survivor_head = NULL;
214 _survivor_tail = NULL;
215 _survivor_length = 0;
216
217 _last_sampled_rs_lengths = 0;
218
219 assert(check_list_empty(false), "just making sure...");
220 }
221
222 bool YoungList::check_list_well_formed() {
223 bool ret = true;
224
225 size_t length = 0;
226 HeapRegion* curr = _head;
227 HeapRegion* last = NULL;
228 while (curr != NULL) {
229 if (!curr->is_young()) {
230 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
231 "incorrectly tagged (y: %d, surv: %d)",
232 curr->bottom(), curr->end(),
233 curr->is_young(), curr->is_survivor());
234 ret = false;
235 }
236 ++length;
237 last = curr;
238 curr = curr->get_next_young_region();
239 }
240 ret = ret && (length == _length);
241
242 if (!ret) {
243 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
244 gclog_or_tty->print_cr("### list has %d entries, _length is %d",
245 length, _length);
246 }
247
248 return ret;
249 }
250
251 bool YoungList::check_list_empty(bool check_sample) {
252 bool ret = true;
253
254 if (_length != 0) {
255 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %d",
256 _length);
257 ret = false;
258 }
259 if (check_sample && _last_sampled_rs_lengths != 0) {
260 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
261 ret = false;
262 }
263 if (_head != NULL) {
264 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
265 ret = false;
266 }
267 if (!ret) {
268 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
269 }
270
271 return ret;
272 }
273
274 void
275 YoungList::rs_length_sampling_init() {
276 _sampled_rs_lengths = 0;
277 _curr = _head;
278 }
279
280 bool
281 YoungList::rs_length_sampling_more() {
282 return _curr != NULL;
283 }
284
285 void
286 YoungList::rs_length_sampling_next() {
287 assert( _curr != NULL, "invariant" );
288 size_t rs_length = _curr->rem_set()->occupied();
289
290 _sampled_rs_lengths += rs_length;
291
292 // The current region may not yet have been added to the
293 // incremental collection set (it gets added when it is
294 // retired as the current allocation region).
295 if (_curr->in_collection_set()) {
296 // Update the collection set policy information for this region
297 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
298 }
299
300 _curr = _curr->get_next_young_region();
301 if (_curr == NULL) {
302 _last_sampled_rs_lengths = _sampled_rs_lengths;
303 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
304 }
305 }
306
307 void
308 YoungList::reset_auxilary_lists() {
309 guarantee( is_empty(), "young list should be empty" );
310 assert(check_list_well_formed(), "young list should be well formed");
311
312 // Add survivor regions to SurvRateGroup.
313 _g1h->g1_policy()->note_start_adding_survivor_regions();
314 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
315
316 for (HeapRegion* curr = _survivor_head;
317 curr != NULL;
318 curr = curr->get_next_young_region()) {
319 _g1h->g1_policy()->set_region_survivors(curr);
320
321 // The region is a non-empty survivor so let's add it to
322 // the incremental collection set for the next evacuation
323 // pause.
324 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
325 }
326 _g1h->g1_policy()->note_stop_adding_survivor_regions();
327
328 _head = _survivor_head;
329 _length = _survivor_length;
330 if (_survivor_head != NULL) {
331 assert(_survivor_tail != NULL, "cause it shouldn't be");
332 assert(_survivor_length > 0, "invariant");
333 _survivor_tail->set_next_young_region(NULL);
334 }
335
336 // Don't clear the survivor list handles until the start of
337 // the next evacuation pause - we need it in order to re-tag
338 // the survivor regions from this evacuation pause as 'young'
339 // at the start of the next.
340
341 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
342
343 assert(check_list_well_formed(), "young list should be well formed");
344 }
345
346 void YoungList::print() {
347 HeapRegion* lists[] = {_head, _survivor_head};
348 const char* names[] = {"YOUNG", "SURVIVOR"};
349
350 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
351 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
352 HeapRegion *curr = lists[list];
353 if (curr == NULL)
354 gclog_or_tty->print_cr(" empty");
355 while (curr != NULL) {
356 gclog_or_tty->print_cr(" [%08x-%08x], t: %08x, P: %08x, N: %08x, C: %08x, "
357 "age: %4d, y: %d, surv: %d",
358 curr->bottom(), curr->end(),
359 curr->top(),
360 curr->prev_top_at_mark_start(),
361 curr->next_top_at_mark_start(),
362 curr->top_at_conc_mark_count(),
363 curr->age_in_surv_rate_group_cond(),
364 curr->is_young(),
365 curr->is_survivor());
366 curr = curr->get_next_young_region();
367 }
368 }
369
370 gclog_or_tty->print_cr("");
371 }
372
373 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
374 {
375 // Claim the right to put the region on the dirty cards region list
376 // by installing a self pointer.
377 HeapRegion* next = hr->get_next_dirty_cards_region();
378 if (next == NULL) {
379 HeapRegion* res = (HeapRegion*)
380 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
381 NULL);
382 if (res == NULL) {
383 HeapRegion* head;
384 do {
385 // Put the region to the dirty cards region list.
386 head = _dirty_cards_region_list;
387 next = (HeapRegion*)
388 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
389 if (next == head) {
390 assert(hr->get_next_dirty_cards_region() == hr,
391 "hr->get_next_dirty_cards_region() != hr");
392 if (next == NULL) {
393 // The last region in the list points to itself.
394 hr->set_next_dirty_cards_region(hr);
395 } else {
396 hr->set_next_dirty_cards_region(next);
397 }
398 }
399 } while (next != head);
400 }
401 }
402 }
403
404 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
405 {
406 HeapRegion* head;
407 HeapRegion* hr;
408 do {
409 head = _dirty_cards_region_list;
410 if (head == NULL) {
411 return NULL;
412 }
413 HeapRegion* new_head = head->get_next_dirty_cards_region();
414 if (head == new_head) {
415 // The last region.
416 new_head = NULL;
417 }
418 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
419 head);
420 } while (hr != head);
421 assert(hr != NULL, "invariant");
422 hr->set_next_dirty_cards_region(NULL);
423 return hr;
424 }
425
426 void G1CollectedHeap::stop_conc_gc_threads() {
427 _cg1r->stop();
428 _cmThread->stop();
429 }
430
431 #ifdef ASSERT
432 // A region is added to the collection set as it is retired
433 // so an address p can point to a region which will be in the
434 // collection set but has not yet been retired. This method
435 // therefore is only accurate during a GC pause after all
436 // regions have been retired. It is used for debugging
437 // to check if an nmethod has references to objects that can
438 // be move during a partial collection. Though it can be
439 // inaccurate, it is sufficient for G1 because the conservative
440 // implementation of is_scavengable() for G1 will indicate that
441 // all nmethods must be scanned during a partial collection.
442 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
443 HeapRegion* hr = heap_region_containing(p);
444 return hr != NULL && hr->in_collection_set();
445 }
446 #endif
447
448 // Returns true if the reference points to an object that
449 // can move in an incremental collecction.
450 bool G1CollectedHeap::is_scavengable(const void* p) {
451 G1CollectedHeap* g1h = G1CollectedHeap::heap();
452 G1CollectorPolicy* g1p = g1h->g1_policy();
453 HeapRegion* hr = heap_region_containing(p);
454 if (hr == NULL) {
455 // perm gen (or null)
456 return false;
457 } else {
458 return !hr->isHumongous();
459 }
460 }
461
462 void G1CollectedHeap::check_ct_logs_at_safepoint() {
463 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
464 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
465
466 // Count the dirty cards at the start.
467 CountNonCleanMemRegionClosure count1(this);
468 ct_bs->mod_card_iterate(&count1);
469 int orig_count = count1.n();
470
471 // First clear the logged cards.
472 ClearLoggedCardTableEntryClosure clear;
473 dcqs.set_closure(&clear);
474 dcqs.apply_closure_to_all_completed_buffers();
475 dcqs.iterate_closure_all_threads(false);
476 clear.print_histo();
477
478 // Now ensure that there's no dirty cards.
479 CountNonCleanMemRegionClosure count2(this);
480 ct_bs->mod_card_iterate(&count2);
481 if (count2.n() != 0) {
482 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
483 count2.n(), orig_count);
484 }
485 guarantee(count2.n() == 0, "Card table should be clean.");
486
487 RedirtyLoggedCardTableEntryClosure redirty;
488 JavaThread::dirty_card_queue_set().set_closure(&redirty);
489 dcqs.apply_closure_to_all_completed_buffers();
490 dcqs.iterate_closure_all_threads(false);
491 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
492 clear.calls(), orig_count);
493 guarantee(redirty.calls() == clear.calls(),
494 "Or else mechanism is broken.");
495
496 CountNonCleanMemRegionClosure count3(this);
497 ct_bs->mod_card_iterate(&count3);
498 if (count3.n() != orig_count) {
499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
500 orig_count, count3.n());
501 guarantee(count3.n() >= orig_count, "Should have restored them all.");
502 }
503
504 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
505 }
506
507 // Private class members.
508
509 G1CollectedHeap* G1CollectedHeap::_g1h;
510
511 // Private methods.
512
513 HeapRegion*
514 G1CollectedHeap::new_region_try_secondary_free_list() {
515 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
516 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
517 if (!_secondary_free_list.is_empty()) {
518 if (G1ConcRegionFreeingVerbose) {
519 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
520 "secondary_free_list has "SIZE_FORMAT" entries",
521 _secondary_free_list.length());
522 }
523 // It looks as if there are free regions available on the
524 // secondary_free_list. Let's move them to the free_list and try
525 // again to allocate from it.
526 append_secondary_free_list();
527
528 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
529 "empty we should have moved at least one entry to the free_list");
530 HeapRegion* res = _free_list.remove_head();
531 if (G1ConcRegionFreeingVerbose) {
532 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
533 "allocated "HR_FORMAT" from secondary_free_list",
534 HR_FORMAT_PARAMS(res));
535 }
536 return res;
537 }
538
539 // Wait here until we get notifed either when (a) there are no
540 // more free regions coming or (b) some regions have been moved on
541 // the secondary_free_list.
542 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
543 }
544
545 if (G1ConcRegionFreeingVerbose) {
546 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
547 "could not allocate from secondary_free_list");
548 }
549 return NULL;
550 }
551
552 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool do_expand) {
553 assert(!isHumongous(word_size) ||
554 word_size <= (size_t) HeapRegion::GrainWords,
555 "the only time we use this to allocate a humongous region is "
556 "when we are allocating a single humongous region");
557
558 HeapRegion* res;
559 if (G1StressConcRegionFreeing) {
560 if (!_secondary_free_list.is_empty()) {
561 if (G1ConcRegionFreeingVerbose) {
562 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
563 "forced to look at the secondary_free_list");
564 }
565 res = new_region_try_secondary_free_list();
566 if (res != NULL) {
567 return res;
568 }
569 }
570 }
571 res = _free_list.remove_head_or_null();
572 if (res == NULL) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "res == NULL, trying the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list();
578 }
579 if (res == NULL && do_expand) {
580 if (expand(word_size * HeapWordSize)) {
581 // Even though the heap was expanded, it might not have reached
582 // the desired size. So, we cannot assume that the allocation
583 // will succeed.
584 res = _free_list.remove_head_or_null();
585 }
586 }
587 return res;
588 }
589
590 HeapRegion* G1CollectedHeap::new_gc_alloc_region(int purpose,
591 size_t word_size) {
592 HeapRegion* alloc_region = NULL;
593 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
594 alloc_region = new_region(word_size, true /* do_expand */);
595 if (alloc_region != NULL) {
596 if (purpose == GCAllocForSurvived) {
597 _hr_printer.alloc(alloc_region, G1HRPrinter::Survivor);
598 alloc_region->set_survivor();
599 } else {
600 _hr_printer.alloc(alloc_region, G1HRPrinter::Old);
601 }
602 ++_gc_alloc_region_counts[purpose];
603 }
604 } else {
605 g1_policy()->note_alloc_region_limit_reached(purpose);
606 }
607 return alloc_region;
608 }
609
610 size_t G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
611 size_t word_size) {
612 assert(isHumongous(word_size), "word_size should be humongous");
613 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
614
615 size_t first = G1_NULL_HRS_INDEX;
616 if (num_regions == 1) {
617 // Only one region to allocate, no need to go through the slower
618 // path. The caller will attempt the expasion if this fails, so
619 // let's not try to expand here too.
620 HeapRegion* hr = new_region(word_size, false /* do_expand */);
621 if (hr != NULL) {
622 first = hr->hrs_index();
623 } else {
624 first = G1_NULL_HRS_INDEX;
625 }
626 } else {
627 // We can't allocate humongous regions while cleanupComplete() is
628 // running, since some of the regions we find to be empty might not
629 // yet be added to the free list and it is not straightforward to
630 // know which list they are on so that we can remove them. Note
631 // that we only need to do this if we need to allocate more than
632 // one region to satisfy the current humongous allocation
633 // request. If we are only allocating one region we use the common
634 // region allocation code (see above).
635 wait_while_free_regions_coming();
636 append_secondary_free_list_if_not_empty_with_lock();
637
638 if (free_regions() >= num_regions) {
639 first = _hrs.find_contiguous(num_regions);
640 if (first != G1_NULL_HRS_INDEX) {
641 for (size_t i = first; i < first + num_regions; ++i) {
642 HeapRegion* hr = region_at(i);
643 assert(hr->is_empty(), "sanity");
644 assert(is_on_master_free_list(hr), "sanity");
645 hr->set_pending_removal(true);
646 }
647 _free_list.remove_all_pending(num_regions);
648 }
649 }
650 }
651 return first;
652 }
653
654 HeapWord*
655 G1CollectedHeap::humongous_obj_allocate_initialize_regions(size_t first,
656 size_t num_regions,
657 size_t word_size) {
658 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
659 assert(isHumongous(word_size), "word_size should be humongous");
660 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
661
662 // Index of last region in the series + 1.
663 size_t last = first + num_regions;
664
665 // We need to initialize the region(s) we just discovered. This is
666 // a bit tricky given that it can happen concurrently with
667 // refinement threads refining cards on these regions and
668 // potentially wanting to refine the BOT as they are scanning
669 // those cards (this can happen shortly after a cleanup; see CR
670 // 6991377). So we have to set up the region(s) carefully and in
671 // a specific order.
672
673 // The word size sum of all the regions we will allocate.
674 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
675 assert(word_size <= word_size_sum, "sanity");
676
677 // This will be the "starts humongous" region.
678 HeapRegion* first_hr = region_at(first);
679 // The header of the new object will be placed at the bottom of
680 // the first region.
681 HeapWord* new_obj = first_hr->bottom();
682 // This will be the new end of the first region in the series that
683 // should also match the end of the last region in the seriers.
684 HeapWord* new_end = new_obj + word_size_sum;
685 // This will be the new top of the first region that will reflect
686 // this allocation.
687 HeapWord* new_top = new_obj + word_size;
688
689 // First, we need to zero the header of the space that we will be
690 // allocating. When we update top further down, some refinement
691 // threads might try to scan the region. By zeroing the header we
692 // ensure that any thread that will try to scan the region will
693 // come across the zero klass word and bail out.
694 //
695 // NOTE: It would not have been correct to have used
696 // CollectedHeap::fill_with_object() and make the space look like
697 // an int array. The thread that is doing the allocation will
698 // later update the object header to a potentially different array
699 // type and, for a very short period of time, the klass and length
700 // fields will be inconsistent. This could cause a refinement
701 // thread to calculate the object size incorrectly.
702 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
703
704 // We will set up the first region as "starts humongous". This
705 // will also update the BOT covering all the regions to reflect
706 // that there is a single object that starts at the bottom of the
707 // first region.
708 first_hr->set_startsHumongous(new_top, new_end);
709
710 // Then, if there are any, we will set up the "continues
711 // humongous" regions.
712 HeapRegion* hr = NULL;
713 for (size_t i = first + 1; i < last; ++i) {
714 hr = region_at(i);
715 hr->set_continuesHumongous(first_hr);
716 }
717 // If we have "continues humongous" regions (hr != NULL), then the
718 // end of the last one should match new_end.
719 assert(hr == NULL || hr->end() == new_end, "sanity");
720
721 // Up to this point no concurrent thread would have been able to
722 // do any scanning on any region in this series. All the top
723 // fields still point to bottom, so the intersection between
724 // [bottom,top] and [card_start,card_end] will be empty. Before we
725 // update the top fields, we'll do a storestore to make sure that
726 // no thread sees the update to top before the zeroing of the
727 // object header and the BOT initialization.
728 OrderAccess::storestore();
729
730 // Now that the BOT and the object header have been initialized,
731 // we can update top of the "starts humongous" region.
732 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
733 "new_top should be in this region");
734 first_hr->set_top(new_top);
735 if (_hr_printer.is_active()) {
736 HeapWord* bottom = first_hr->bottom();
737 HeapWord* end = first_hr->orig_end();
738 if ((first + 1) == last) {
739 // the series has a single humongous region
740 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
741 } else {
742 // the series has more than one humongous regions
743 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
744 }
745 }
746
747 // Now, we will update the top fields of the "continues humongous"
748 // regions. The reason we need to do this is that, otherwise,
749 // these regions would look empty and this will confuse parts of
750 // G1. For example, the code that looks for a consecutive number
751 // of empty regions will consider them empty and try to
752 // re-allocate them. We can extend is_empty() to also include
753 // !continuesHumongous(), but it is easier to just update the top
754 // fields here. The way we set top for all regions (i.e., top ==
755 // end for all regions but the last one, top == new_top for the
756 // last one) is actually used when we will free up the humongous
757 // region in free_humongous_region().
758 hr = NULL;
759 for (size_t i = first + 1; i < last; ++i) {
760 hr = region_at(i);
761 if ((i + 1) == last) {
762 // last continues humongous region
763 assert(hr->bottom() < new_top && new_top <= hr->end(),
764 "new_top should fall on this region");
765 hr->set_top(new_top);
766 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
767 } else {
768 // not last one
769 assert(new_top > hr->end(), "new_top should be above this region");
770 hr->set_top(hr->end());
771 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
772 }
773 }
774 // If we have continues humongous regions (hr != NULL), then the
775 // end of the last one should match new_end and its top should
776 // match new_top.
777 assert(hr == NULL ||
778 (hr->end() == new_end && hr->top() == new_top), "sanity");
779
780 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
781 _summary_bytes_used += first_hr->used();
782 _humongous_set.add(first_hr);
783
784 return new_obj;
785 }
786
787 // If could fit into free regions w/o expansion, try.
788 // Otherwise, if can expand, do so.
789 // Otherwise, if using ex regions might help, try with ex given back.
790 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
791 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
792
793 verify_region_sets_optional();
794
795 size_t num_regions =
796 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
797 size_t x_size = expansion_regions();
798 size_t fs = _hrs.free_suffix();
799 size_t first = humongous_obj_allocate_find_first(num_regions, word_size);
800 if (first == G1_NULL_HRS_INDEX) {
801 // The only thing we can do now is attempt expansion.
802 if (fs + x_size >= num_regions) {
803 // If the number of regions we're trying to allocate for this
804 // object is at most the number of regions in the free suffix,
805 // then the call to humongous_obj_allocate_find_first() above
806 // should have succeeded and we wouldn't be here.
807 //
808 // We should only be trying to expand when the free suffix is
809 // not sufficient for the object _and_ we have some expansion
810 // room available.
811 assert(num_regions > fs, "earlier allocation should have succeeded");
812
813 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
814 // Even though the heap was expanded, it might not have
815 // reached the desired size. So, we cannot assume that the
816 // allocation will succeed.
817 first = humongous_obj_allocate_find_first(num_regions, word_size);
818 }
819 }
820 }
821
822 HeapWord* result = NULL;
823 if (first != G1_NULL_HRS_INDEX) {
824 result =
825 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
826 assert(result != NULL, "it should always return a valid result");
827 }
828
829 verify_region_sets_optional();
830
831 return result;
832 }
833
834 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
835 assert_heap_not_locked_and_not_at_safepoint();
836 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
837
838 unsigned int dummy_gc_count_before;
839 return attempt_allocation(word_size, &dummy_gc_count_before);
840 }
841
842 HeapWord*
843 G1CollectedHeap::mem_allocate(size_t word_size,
844 bool* gc_overhead_limit_was_exceeded) {
845 assert_heap_not_locked_and_not_at_safepoint();
846
847 // Loop until the allocation is satisified, or unsatisfied after GC.
848 for (int try_count = 1; /* we'll return */; try_count += 1) {
849 unsigned int gc_count_before;
850
851 HeapWord* result = NULL;
852 if (!isHumongous(word_size)) {
853 result = attempt_allocation(word_size, &gc_count_before);
854 } else {
855 result = attempt_allocation_humongous(word_size, &gc_count_before);
856 }
857 if (result != NULL) {
858 return result;
859 }
860
861 // Create the garbage collection operation...
862 VM_G1CollectForAllocation op(gc_count_before, word_size);
863 // ...and get the VM thread to execute it.
864 VMThread::execute(&op);
865
866 if (op.prologue_succeeded() && op.pause_succeeded()) {
867 // If the operation was successful we'll return the result even
868 // if it is NULL. If the allocation attempt failed immediately
869 // after a Full GC, it's unlikely we'll be able to allocate now.
870 HeapWord* result = op.result();
871 if (result != NULL && !isHumongous(word_size)) {
872 // Allocations that take place on VM operations do not do any
873 // card dirtying and we have to do it here. We only have to do
874 // this for non-humongous allocations, though.
875 dirty_young_block(result, word_size);
876 }
877 return result;
878 } else {
879 assert(op.result() == NULL,
880 "the result should be NULL if the VM op did not succeed");
881 }
882
883 // Give a warning if we seem to be looping forever.
884 if ((QueuedAllocationWarningCount > 0) &&
885 (try_count % QueuedAllocationWarningCount == 0)) {
886 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
887 }
888 }
889
890 ShouldNotReachHere();
891 return NULL;
892 }
893
894 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
895 unsigned int *gc_count_before_ret) {
896 // Make sure you read the note in attempt_allocation_humongous().
897
898 assert_heap_not_locked_and_not_at_safepoint();
899 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
900 "be called for humongous allocation requests");
901
902 // We should only get here after the first-level allocation attempt
903 // (attempt_allocation()) failed to allocate.
904
905 // We will loop until a) we manage to successfully perform the
906 // allocation or b) we successfully schedule a collection which
907 // fails to perform the allocation. b) is the only case when we'll
908 // return NULL.
909 HeapWord* result = NULL;
910 for (int try_count = 1; /* we'll return */; try_count += 1) {
911 bool should_try_gc;
912 unsigned int gc_count_before;
913
914 {
915 MutexLockerEx x(Heap_lock);
916
917 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
918 false /* bot_updates */);
919 if (result != NULL) {
920 return result;
921 }
922
923 // If we reach here, attempt_allocation_locked() above failed to
924 // allocate a new region. So the mutator alloc region should be NULL.
925 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
926
927 if (GC_locker::is_active_and_needs_gc()) {
928 if (g1_policy()->can_expand_young_list()) {
929 result = _mutator_alloc_region.attempt_allocation_force(word_size,
930 false /* bot_updates */);
931 if (result != NULL) {
932 return result;
933 }
934 }
935 should_try_gc = false;
936 } else {
937 // Read the GC count while still holding the Heap_lock.
938 gc_count_before = SharedHeap::heap()->total_collections();
939 should_try_gc = true;
940 }
941 }
942
943 if (should_try_gc) {
944 bool succeeded;
945 result = do_collection_pause(word_size, gc_count_before, &succeeded);
946 if (result != NULL) {
947 assert(succeeded, "only way to get back a non-NULL result");
948 return result;
949 }
950
951 if (succeeded) {
952 // If we get here we successfully scheduled a collection which
953 // failed to allocate. No point in trying to allocate
954 // further. We'll just return NULL.
955 MutexLockerEx x(Heap_lock);
956 *gc_count_before_ret = SharedHeap::heap()->total_collections();
957 return NULL;
958 }
959 } else {
960 GC_locker::stall_until_clear();
961 }
962
963 // We can reach here if we were unsuccessul in scheduling a
964 // collection (because another thread beat us to it) or if we were
965 // stalled due to the GC locker. In either can we should retry the
966 // allocation attempt in case another thread successfully
967 // performed a collection and reclaimed enough space. We do the
968 // first attempt (without holding the Heap_lock) here and the
969 // follow-on attempt will be at the start of the next loop
970 // iteration (after taking the Heap_lock).
971 result = _mutator_alloc_region.attempt_allocation(word_size,
972 false /* bot_updates */);
973 if (result != NULL ){
974 return result;
975 }
976
977 // Give a warning if we seem to be looping forever.
978 if ((QueuedAllocationWarningCount > 0) &&
979 (try_count % QueuedAllocationWarningCount == 0)) {
980 warning("G1CollectedHeap::attempt_allocation_slow() "
981 "retries %d times", try_count);
982 }
983 }
984
985 ShouldNotReachHere();
986 return NULL;
987 }
988
989 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
990 unsigned int * gc_count_before_ret) {
991 // The structure of this method has a lot of similarities to
992 // attempt_allocation_slow(). The reason these two were not merged
993 // into a single one is that such a method would require several "if
994 // allocation is not humongous do this, otherwise do that"
995 // conditional paths which would obscure its flow. In fact, an early
996 // version of this code did use a unified method which was harder to
997 // follow and, as a result, it had subtle bugs that were hard to
998 // track down. So keeping these two methods separate allows each to
999 // be more readable. It will be good to keep these two in sync as
1000 // much as possible.
1001
1002 assert_heap_not_locked_and_not_at_safepoint();
1003 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1004 "should only be called for humongous allocations");
1005
1006 // We will loop until a) we manage to successfully perform the
1007 // allocation or b) we successfully schedule a collection which
1008 // fails to perform the allocation. b) is the only case when we'll
1009 // return NULL.
1010 HeapWord* result = NULL;
1011 for (int try_count = 1; /* we'll return */; try_count += 1) {
1012 bool should_try_gc;
1013 unsigned int gc_count_before;
1014
1015 {
1016 MutexLockerEx x(Heap_lock);
1017
1018 // Given that humongous objects are not allocated in young
1019 // regions, we'll first try to do the allocation without doing a
1020 // collection hoping that there's enough space in the heap.
1021 result = humongous_obj_allocate(word_size);
1022 if (result != NULL) {
1023 return result;
1024 }
1025
1026 if (GC_locker::is_active_and_needs_gc()) {
1027 should_try_gc = false;
1028 } else {
1029 // Read the GC count while still holding the Heap_lock.
1030 gc_count_before = SharedHeap::heap()->total_collections();
1031 should_try_gc = true;
1032 }
1033 }
1034
1035 if (should_try_gc) {
1036 // If we failed to allocate the humongous object, we should try to
1037 // do a collection pause (if we're allowed) in case it reclaims
1038 // enough space for the allocation to succeed after the pause.
1039
1040 bool succeeded;
1041 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1042 if (result != NULL) {
1043 assert(succeeded, "only way to get back a non-NULL result");
1044 return result;
1045 }
1046
1047 if (succeeded) {
1048 // If we get here we successfully scheduled a collection which
1049 // failed to allocate. No point in trying to allocate
1050 // further. We'll just return NULL.
1051 MutexLockerEx x(Heap_lock);
1052 *gc_count_before_ret = SharedHeap::heap()->total_collections();
1053 return NULL;
1054 }
1055 } else {
1056 GC_locker::stall_until_clear();
1057 }
1058
1059 // We can reach here if we were unsuccessul in scheduling a
1060 // collection (because another thread beat us to it) or if we were
1061 // stalled due to the GC locker. In either can we should retry the
1062 // allocation attempt in case another thread successfully
1063 // performed a collection and reclaimed enough space. Give a
1064 // warning if we seem to be looping forever.
1065
1066 if ((QueuedAllocationWarningCount > 0) &&
1067 (try_count % QueuedAllocationWarningCount == 0)) {
1068 warning("G1CollectedHeap::attempt_allocation_humongous() "
1069 "retries %d times", try_count);
1070 }
1071 }
1072
1073 ShouldNotReachHere();
1074 return NULL;
1075 }
1076
1077 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1078 bool expect_null_mutator_alloc_region) {
1079 assert_at_safepoint(true /* should_be_vm_thread */);
1080 assert(_mutator_alloc_region.get() == NULL ||
1081 !expect_null_mutator_alloc_region,
1082 "the current alloc region was unexpectedly found to be non-NULL");
1083
1084 if (!isHumongous(word_size)) {
1085 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1086 false /* bot_updates */);
1087 } else {
1088 return humongous_obj_allocate(word_size);
1089 }
1090
1091 ShouldNotReachHere();
1092 }
1093
1094 void G1CollectedHeap::abandon_gc_alloc_regions() {
1095 // first, make sure that the GC alloc region list is empty (it should!)
1096 assert(_gc_alloc_region_list == NULL, "invariant");
1097 release_gc_alloc_regions(true /* totally */);
1098 }
1099
1100 class PostMCRemSetClearClosure: public HeapRegionClosure {
1101 ModRefBarrierSet* _mr_bs;
1102 public:
1103 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1104 bool doHeapRegion(HeapRegion* r) {
1105 r->reset_gc_time_stamp();
1106 if (r->continuesHumongous())
1107 return false;
1108 HeapRegionRemSet* hrrs = r->rem_set();
1109 if (hrrs != NULL) hrrs->clear();
1110 // You might think here that we could clear just the cards
1111 // corresponding to the used region. But no: if we leave a dirty card
1112 // in a region we might allocate into, then it would prevent that card
1113 // from being enqueued, and cause it to be missed.
1114 // Re: the performance cost: we shouldn't be doing full GC anyway!
1115 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1116 return false;
1117 }
1118 };
1119
1120
1121 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1122 ModRefBarrierSet* _mr_bs;
1123 public:
1124 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1125 bool doHeapRegion(HeapRegion* r) {
1126 if (r->continuesHumongous()) return false;
1127 if (r->used_region().word_size() != 0) {
1128 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1129 }
1130 return false;
1131 }
1132 };
1133
1134 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1135 G1CollectedHeap* _g1h;
1136 UpdateRSOopClosure _cl;
1137 int _worker_i;
1138 public:
1139 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1140 _cl(g1->g1_rem_set(), worker_i),
1141 _worker_i(worker_i),
1142 _g1h(g1)
1143 { }
1144
1145 bool doHeapRegion(HeapRegion* r) {
1146 if (!r->continuesHumongous()) {
1147 _cl.set_from(r);
1148 r->oop_iterate(&_cl);
1149 }
1150 return false;
1151 }
1152 };
1153
1154 class ParRebuildRSTask: public AbstractGangTask {
1155 G1CollectedHeap* _g1;
1156 public:
1157 ParRebuildRSTask(G1CollectedHeap* g1)
1158 : AbstractGangTask("ParRebuildRSTask"),
1159 _g1(g1)
1160 { }
1161
1162 void work(int i) {
1163 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1164 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1165 HeapRegion::RebuildRSClaimValue);
1166 }
1167 };
1168
1169 class PostCompactionPrinterClosure: public HeapRegionClosure {
1170 private:
1171 G1HRPrinter* _hr_printer;
1172 public:
1173 bool doHeapRegion(HeapRegion* hr) {
1174 assert(!hr->is_young(), "not expecting to find young regions");
1175 // We only generate output for non-empty regions.
1176 if (!hr->is_empty()) {
1177 if (!hr->isHumongous()) {
1178 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1179 } else if (hr->startsHumongous()) {
1180 if (hr->capacity() == (size_t) HeapRegion::GrainBytes) {
1181 // single humongous region
1182 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1183 } else {
1184 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1185 }
1186 } else {
1187 assert(hr->continuesHumongous(), "only way to get here");
1188 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1189 }
1190 }
1191 return false;
1192 }
1193
1194 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1195 : _hr_printer(hr_printer) { }
1196 };
1197
1198 bool G1CollectedHeap::do_collection(bool explicit_gc,
1199 bool clear_all_soft_refs,
1200 size_t word_size) {
1201 assert_at_safepoint(true /* should_be_vm_thread */);
1202
1203 if (GC_locker::check_active_before_gc()) {
1204 return false;
1205 }
1206
1207 SvcGCMarker sgcm(SvcGCMarker::FULL);
1208 ResourceMark rm;
1209
1210 if (PrintHeapAtGC) {
1211 Universe::print_heap_before_gc();
1212 }
1213
1214 verify_region_sets_optional();
1215
1216 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1217 collector_policy()->should_clear_all_soft_refs();
1218
1219 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1220
1221 {
1222 IsGCActiveMark x;
1223
1224 // Timing
1225 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1226 assert(!system_gc || explicit_gc, "invariant");
1227 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1228 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1229 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1230 PrintGC, true, gclog_or_tty);
1231
1232 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1233 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1234
1235 double start = os::elapsedTime();
1236 g1_policy()->record_full_collection_start();
1237
1238 wait_while_free_regions_coming();
1239 append_secondary_free_list_if_not_empty_with_lock();
1240
1241 gc_prologue(true);
1242 increment_total_collections(true /* full gc */);
1243
1244 size_t g1h_prev_used = used();
1245 assert(used() == recalculate_used(), "Should be equal");
1246
1247 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1248 HandleMark hm; // Discard invalid handles created during verification
1249 gclog_or_tty->print(" VerifyBeforeGC:");
1250 prepare_for_verify();
1251 Universe::verify(/* allow dirty */ true,
1252 /* silent */ false,
1253 /* option */ VerifyOption_G1UsePrevMarking);
1254
1255 }
1256
1257 COMPILER2_PRESENT(DerivedPointerTable::clear());
1258
1259 // We want to discover references, but not process them yet.
1260 // This mode is disabled in
1261 // instanceRefKlass::process_discovered_references if the
1262 // generation does some collection work, or
1263 // instanceRefKlass::enqueue_discovered_references if the
1264 // generation returns without doing any work.
1265
1266 // Disable discovery and empty the discovered lists
1267 // for the CM ref processor.
1268 ref_processor_cm()->disable_discovery();
1269 ref_processor_cm()->abandon_partial_discovery();
1270 ref_processor_cm()->verify_no_references_recorded();
1271
1272 // Abandon current iterations of concurrent marking and concurrent
1273 // refinement, if any are in progress.
1274 concurrent_mark()->abort();
1275
1276 // Make sure we'll choose a new allocation region afterwards.
1277 release_mutator_alloc_region();
1278 abandon_gc_alloc_regions();
1279 g1_rem_set()->cleanupHRRS();
1280 tear_down_region_lists();
1281
1282 // We should call this after we retire any currently active alloc
1283 // regions so that all the ALLOC / RETIRE events are generated
1284 // before the start GC event.
1285 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1286
1287 // We may have added regions to the current incremental collection
1288 // set between the last GC or pause and now. We need to clear the
1289 // incremental collection set and then start rebuilding it afresh
1290 // after this full GC.
1291 abandon_collection_set(g1_policy()->inc_cset_head());
1292 g1_policy()->clear_incremental_cset();
1293 g1_policy()->stop_incremental_cset_building();
1294
1295 if (g1_policy()->in_young_gc_mode()) {
1296 empty_young_list();
1297 g1_policy()->set_full_young_gcs(true);
1298 }
1299
1300 // See the comments in g1CollectedHeap.hpp and
1301 // G1CollectedHeap::ref_processing_init() about
1302 // how reference processing currently works in G1.
1303
1304 assert(!ref_processor_stw()->discovery_enabled(), "Precondition");
1305 ref_processor_stw()->verify_no_references_recorded();
1306
1307 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1308 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1309
1310 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1311 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1312
1313 ref_processor_stw()->enable_discovery();
1314 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1315
1316 // Do collection work
1317 {
1318 HandleMark hm; // Discard invalid handles created during gc
1319 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1320 }
1321
1322 assert(free_regions() == 0, "we should not have added any free regions");
1323 rebuild_region_lists();
1324
1325 _summary_bytes_used = recalculate_used();
1326
1327 // Enqueue any discovered reference objects that have
1328 // not been removed from the discovered lists.
1329 ref_processor_stw()->enqueue_discovered_references();
1330
1331 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1332
1333 MemoryService::track_memory_usage();
1334
1335 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1336 HandleMark hm; // Discard invalid handles created during verification
1337 gclog_or_tty->print(" VerifyAfterGC:");
1338 prepare_for_verify();
1339 Universe::verify(/* allow dirty */ false,
1340 /* silent */ false,
1341 /* option */ VerifyOption_G1UsePrevMarking);
1342
1343 }
1344
1345 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1346 ref_processor_stw()->verify_no_references_recorded();
1347
1348 // Note: since we've just done a full GC, concurrent
1349 // marking is no longer active. Therefore we need not
1350 // re-enable reference discovery for the CM ref processor.
1351 // That will be done at the start of the next marking cycle.
1352 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1353 ref_processor_cm()->verify_no_references_recorded();
1354
1355 reset_gc_time_stamp();
1356 // Since everything potentially moved, we will clear all remembered
1357 // sets, and clear all cards. Later we will rebuild remebered
1358 // sets. We will also reset the GC time stamps of the regions.
1359 PostMCRemSetClearClosure rs_clear(mr_bs());
1360 heap_region_iterate(&rs_clear);
1361
1362 // Resize the heap if necessary.
1363 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1364
1365 if (_hr_printer.is_active()) {
1366 // We should do this after we potentially resize the heap so
1367 // that all the COMMIT / UNCOMMIT events are generated before
1368 // the end GC event.
1369
1370 PostCompactionPrinterClosure cl(hr_printer());
1371 heap_region_iterate(&cl);
1372
1373 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1374 }
1375
1376 if (_cg1r->use_cache()) {
1377 _cg1r->clear_and_record_card_counts();
1378 _cg1r->clear_hot_cache();
1379 }
1380
1381 // Rebuild remembered sets of all regions.
1382
1383 if (G1CollectedHeap::use_parallel_gc_threads()) {
1384 ParRebuildRSTask rebuild_rs_task(this);
1385 assert(check_heap_region_claim_values(
1386 HeapRegion::InitialClaimValue), "sanity check");
1387 set_par_threads(workers()->total_workers());
1388 workers()->run_task(&rebuild_rs_task);
1389 set_par_threads(0);
1390 assert(check_heap_region_claim_values(
1391 HeapRegion::RebuildRSClaimValue), "sanity check");
1392 reset_heap_region_claim_values();
1393 } else {
1394 RebuildRSOutOfRegionClosure rebuild_rs(this);
1395 heap_region_iterate(&rebuild_rs);
1396 }
1397
1398 if (PrintGC) {
1399 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1400 }
1401
1402 if (true) { // FIXME
1403 // Ask the permanent generation to adjust size for full collections
1404 perm()->compute_new_size();
1405 }
1406
1407 // Start a new incremental collection set for the next pause
1408 assert(g1_policy()->collection_set() == NULL, "must be");
1409 g1_policy()->start_incremental_cset_building();
1410
1411 // Clear the _cset_fast_test bitmap in anticipation of adding
1412 // regions to the incremental collection set for the next
1413 // evacuation pause.
1414 clear_cset_fast_test();
1415
1416 init_mutator_alloc_region();
1417
1418 double end = os::elapsedTime();
1419 g1_policy()->record_full_collection_end();
1420
1421 #ifdef TRACESPINNING
1422 ParallelTaskTerminator::print_termination_counts();
1423 #endif
1424
1425 gc_epilogue(true);
1426
1427 // Discard all rset updates
1428 JavaThread::dirty_card_queue_set().abandon_logs();
1429 assert(!G1DeferredRSUpdate
1430 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1431 }
1432
1433 if (g1_policy()->in_young_gc_mode()) {
1434 _young_list->reset_sampled_info();
1435 // At this point there should be no regions in the
1436 // entire heap tagged as young.
1437 assert( check_young_list_empty(true /* check_heap */),
1438 "young list should be empty at this point");
1439 }
1440
1441 // Update the number of full collections that have been completed.
1442 increment_full_collections_completed(false /* concurrent */);
1443
1444 _hrs.verify_optional();
1445 verify_region_sets_optional();
1446
1447 if (PrintHeapAtGC) {
1448 Universe::print_heap_after_gc();
1449 }
1450 g1mm()->update_counters();
1451
1452 return true;
1453 }
1454
1455 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1456 // do_collection() will return whether it succeeded in performing
1457 // the GC. Currently, there is no facility on the
1458 // do_full_collection() API to notify the caller than the collection
1459 // did not succeed (e.g., because it was locked out by the GC
1460 // locker). So, right now, we'll ignore the return value.
1461 bool dummy = do_collection(true, /* explicit_gc */
1462 clear_all_soft_refs,
1463 0 /* word_size */);
1464 }
1465
1466 // This code is mostly copied from TenuredGeneration.
1467 void
1468 G1CollectedHeap::
1469 resize_if_necessary_after_full_collection(size_t word_size) {
1470 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1471
1472 // Include the current allocation, if any, and bytes that will be
1473 // pre-allocated to support collections, as "used".
1474 const size_t used_after_gc = used();
1475 const size_t capacity_after_gc = capacity();
1476 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1477
1478 // This is enforced in arguments.cpp.
1479 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1480 "otherwise the code below doesn't make sense");
1481
1482 // We don't have floating point command-line arguments
1483 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1484 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1485 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1486 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1487
1488 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1489 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1490
1491 // We have to be careful here as these two calculations can overflow
1492 // 32-bit size_t's.
1493 double used_after_gc_d = (double) used_after_gc;
1494 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1495 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1496
1497 // Let's make sure that they are both under the max heap size, which
1498 // by default will make them fit into a size_t.
1499 double desired_capacity_upper_bound = (double) max_heap_size;
1500 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1501 desired_capacity_upper_bound);
1502 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1503 desired_capacity_upper_bound);
1504
1505 // We can now safely turn them into size_t's.
1506 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1507 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1508
1509 // This assert only makes sense here, before we adjust them
1510 // with respect to the min and max heap size.
1511 assert(minimum_desired_capacity <= maximum_desired_capacity,
1512 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1513 "maximum_desired_capacity = "SIZE_FORMAT,
1514 minimum_desired_capacity, maximum_desired_capacity));
1515
1516 // Should not be greater than the heap max size. No need to adjust
1517 // it with respect to the heap min size as it's a lower bound (i.e.,
1518 // we'll try to make the capacity larger than it, not smaller).
1519 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1520 // Should not be less than the heap min size. No need to adjust it
1521 // with respect to the heap max size as it's an upper bound (i.e.,
1522 // we'll try to make the capacity smaller than it, not greater).
1523 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1524
1525 if (PrintGC && Verbose) {
1526 const double free_percentage =
1527 (double) free_after_gc / (double) capacity_after_gc;
1528 gclog_or_tty->print_cr("Computing new size after full GC ");
1529 gclog_or_tty->print_cr(" "
1530 " minimum_free_percentage: %6.2f",
1531 minimum_free_percentage);
1532 gclog_or_tty->print_cr(" "
1533 " maximum_free_percentage: %6.2f",
1534 maximum_free_percentage);
1535 gclog_or_tty->print_cr(" "
1536 " capacity: %6.1fK"
1537 " minimum_desired_capacity: %6.1fK"
1538 " maximum_desired_capacity: %6.1fK",
1539 (double) capacity_after_gc / (double) K,
1540 (double) minimum_desired_capacity / (double) K,
1541 (double) maximum_desired_capacity / (double) K);
1542 gclog_or_tty->print_cr(" "
1543 " free_after_gc: %6.1fK"
1544 " used_after_gc: %6.1fK",
1545 (double) free_after_gc / (double) K,
1546 (double) used_after_gc / (double) K);
1547 gclog_or_tty->print_cr(" "
1548 " free_percentage: %6.2f",
1549 free_percentage);
1550 }
1551 if (capacity_after_gc < minimum_desired_capacity) {
1552 // Don't expand unless it's significant
1553 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1554 if (expand(expand_bytes)) {
1555 if (PrintGC && Verbose) {
1556 gclog_or_tty->print_cr(" "
1557 " expanding:"
1558 " max_heap_size: %6.1fK"
1559 " minimum_desired_capacity: %6.1fK"
1560 " expand_bytes: %6.1fK",
1561 (double) max_heap_size / (double) K,
1562 (double) minimum_desired_capacity / (double) K,
1563 (double) expand_bytes / (double) K);
1564 }
1565 }
1566
1567 // No expansion, now see if we want to shrink
1568 } else if (capacity_after_gc > maximum_desired_capacity) {
1569 // Capacity too large, compute shrinking size
1570 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1571 shrink(shrink_bytes);
1572 if (PrintGC && Verbose) {
1573 gclog_or_tty->print_cr(" "
1574 " shrinking:"
1575 " min_heap_size: %6.1fK"
1576 " maximum_desired_capacity: %6.1fK"
1577 " shrink_bytes: %6.1fK",
1578 (double) min_heap_size / (double) K,
1579 (double) maximum_desired_capacity / (double) K,
1580 (double) shrink_bytes / (double) K);
1581 }
1582 }
1583 }
1584
1585
1586 HeapWord*
1587 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1588 bool* succeeded) {
1589 assert_at_safepoint(true /* should_be_vm_thread */);
1590
1591 *succeeded = true;
1592 // Let's attempt the allocation first.
1593 HeapWord* result =
1594 attempt_allocation_at_safepoint(word_size,
1595 false /* expect_null_mutator_alloc_region */);
1596 if (result != NULL) {
1597 assert(*succeeded, "sanity");
1598 return result;
1599 }
1600
1601 // In a G1 heap, we're supposed to keep allocation from failing by
1602 // incremental pauses. Therefore, at least for now, we'll favor
1603 // expansion over collection. (This might change in the future if we can
1604 // do something smarter than full collection to satisfy a failed alloc.)
1605 result = expand_and_allocate(word_size);
1606 if (result != NULL) {
1607 assert(*succeeded, "sanity");
1608 return result;
1609 }
1610
1611 // Expansion didn't work, we'll try to do a Full GC.
1612 bool gc_succeeded = do_collection(false, /* explicit_gc */
1613 false, /* clear_all_soft_refs */
1614 word_size);
1615 if (!gc_succeeded) {
1616 *succeeded = false;
1617 return NULL;
1618 }
1619
1620 // Retry the allocation
1621 result = attempt_allocation_at_safepoint(word_size,
1622 true /* expect_null_mutator_alloc_region */);
1623 if (result != NULL) {
1624 assert(*succeeded, "sanity");
1625 return result;
1626 }
1627
1628 // Then, try a Full GC that will collect all soft references.
1629 gc_succeeded = do_collection(false, /* explicit_gc */
1630 true, /* clear_all_soft_refs */
1631 word_size);
1632 if (!gc_succeeded) {
1633 *succeeded = false;
1634 return NULL;
1635 }
1636
1637 // Retry the allocation once more
1638 result = attempt_allocation_at_safepoint(word_size,
1639 true /* expect_null_mutator_alloc_region */);
1640 if (result != NULL) {
1641 assert(*succeeded, "sanity");
1642 return result;
1643 }
1644
1645 assert(!collector_policy()->should_clear_all_soft_refs(),
1646 "Flag should have been handled and cleared prior to this point");
1647
1648 // What else? We might try synchronous finalization later. If the total
1649 // space available is large enough for the allocation, then a more
1650 // complete compaction phase than we've tried so far might be
1651 // appropriate.
1652 assert(*succeeded, "sanity");
1653 return NULL;
1654 }
1655
1656 // Attempting to expand the heap sufficiently
1657 // to support an allocation of the given "word_size". If
1658 // successful, perform the allocation and return the address of the
1659 // allocated block, or else "NULL".
1660
1661 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1662 assert_at_safepoint(true /* should_be_vm_thread */);
1663
1664 verify_region_sets_optional();
1665
1666 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1667 if (expand(expand_bytes)) {
1668 _hrs.verify_optional();
1669 verify_region_sets_optional();
1670 return attempt_allocation_at_safepoint(word_size,
1671 false /* expect_null_mutator_alloc_region */);
1672 }
1673 return NULL;
1674 }
1675
1676 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1677 HeapWord* new_end) {
1678 assert(old_end != new_end, "don't call this otherwise");
1679 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1680
1681 // Update the committed mem region.
1682 _g1_committed.set_end(new_end);
1683 // Tell the card table about the update.
1684 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1685 // Tell the BOT about the update.
1686 _bot_shared->resize(_g1_committed.word_size());
1687 }
1688
1689 bool G1CollectedHeap::expand(size_t expand_bytes) {
1690 size_t old_mem_size = _g1_storage.committed_size();
1691 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1692 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1693 HeapRegion::GrainBytes);
1694
1695 if (Verbose && PrintGC) {
1696 gclog_or_tty->print("Expanding garbage-first heap from %ldK by %ldK",
1697 old_mem_size/K, aligned_expand_bytes/K);
1698 }
1699
1700 // First commit the memory.
1701 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1702 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1703 if (successful) {
1704 // Then propagate this update to the necessary data structures.
1705 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1706 update_committed_space(old_end, new_end);
1707
1708 FreeRegionList expansion_list("Local Expansion List");
1709 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1710 assert(mr.start() == old_end, "post-condition");
1711 // mr might be a smaller region than what was requested if
1712 // expand_by() was unable to allocate the HeapRegion instances
1713 assert(mr.end() <= new_end, "post-condition");
1714
1715 size_t actual_expand_bytes = mr.byte_size();
1716 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1717 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1718 "post-condition");
1719 if (actual_expand_bytes < aligned_expand_bytes) {
1720 // We could not expand _hrs to the desired size. In this case we
1721 // need to shrink the committed space accordingly.
1722 assert(mr.end() < new_end, "invariant");
1723
1724 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1725 // First uncommit the memory.
1726 _g1_storage.shrink_by(diff_bytes);
1727 // Then propagate this update to the necessary data structures.
1728 update_committed_space(new_end, mr.end());
1729 }
1730 _free_list.add_as_tail(&expansion_list);
1731
1732 if (_hr_printer.is_active()) {
1733 HeapWord* curr = mr.start();
1734 while (curr < mr.end()) {
1735 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1736 _hr_printer.commit(curr, curr_end);
1737 curr = curr_end;
1738 }
1739 assert(curr == mr.end(), "post-condition");
1740 }
1741 } else {
1742 // The expansion of the virtual storage space was unsuccessful.
1743 // Let's see if it was because we ran out of swap.
1744 if (G1ExitOnExpansionFailure &&
1745 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1746 // We had head room...
1747 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1748 }
1749 }
1750
1751 if (Verbose && PrintGC) {
1752 size_t new_mem_size = _g1_storage.committed_size();
1753 gclog_or_tty->print_cr("...%s, expanded to %ldK",
1754 (successful ? "Successful" : "Failed"),
1755 new_mem_size/K);
1756 }
1757 return successful;
1758 }
1759
1760 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1761 size_t old_mem_size = _g1_storage.committed_size();
1762 size_t aligned_shrink_bytes =
1763 ReservedSpace::page_align_size_down(shrink_bytes);
1764 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1765 HeapRegion::GrainBytes);
1766 size_t num_regions_deleted = 0;
1767 MemRegion mr = _hrs.shrink_by(aligned_shrink_bytes, &num_regions_deleted);
1768 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1769 assert(mr.end() == old_end, "post-condition");
1770 if (mr.byte_size() > 0) {
1771 if (_hr_printer.is_active()) {
1772 HeapWord* curr = mr.end();
1773 while (curr > mr.start()) {
1774 HeapWord* curr_end = curr;
1775 curr -= HeapRegion::GrainWords;
1776 _hr_printer.uncommit(curr, curr_end);
1777 }
1778 assert(curr == mr.start(), "post-condition");
1779 }
1780
1781 _g1_storage.shrink_by(mr.byte_size());
1782 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1783 assert(mr.start() == new_end, "post-condition");
1784
1785 _expansion_regions += num_regions_deleted;
1786 update_committed_space(old_end, new_end);
1787 HeapRegionRemSet::shrink_heap(n_regions());
1788
1789 if (Verbose && PrintGC) {
1790 size_t new_mem_size = _g1_storage.committed_size();
1791 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1792 old_mem_size/K, aligned_shrink_bytes/K,
1793 new_mem_size/K);
1794 }
1795 }
1796 }
1797
1798 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1799 verify_region_sets_optional();
1800
1801 release_gc_alloc_regions(true /* totally */);
1802 // Instead of tearing down / rebuilding the free lists here, we
1803 // could instead use the remove_all_pending() method on free_list to
1804 // remove only the ones that we need to remove.
1805 tear_down_region_lists(); // We will rebuild them in a moment.
1806 shrink_helper(shrink_bytes);
1807 rebuild_region_lists();
1808
1809 _hrs.verify_optional();
1810 verify_region_sets_optional();
1811 }
1812
1813 // Public methods.
1814
1815 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1816 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1817 #endif // _MSC_VER
1818
1819
1820 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1821 SharedHeap(policy_),
1822 _g1_policy(policy_),
1823 _dirty_card_queue_set(false),
1824 _into_cset_dirty_card_queue_set(false),
1825 _is_alive_closure_cm(this),
1826 _is_alive_closure_stw(this),
1827 _ref_processor_cm(NULL),
1828 _ref_processor_stw(NULL),
1829 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1830 _bot_shared(NULL),
1831 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1832 _evac_failure_scan_stack(NULL) ,
1833 _mark_in_progress(false),
1834 _cg1r(NULL), _summary_bytes_used(0),
1835 _refine_cte_cl(NULL),
1836 _full_collection(false),
1837 _free_list("Master Free List"),
1838 _secondary_free_list("Secondary Free List"),
1839 _humongous_set("Master Humongous Set"),
1840 _free_regions_coming(false),
1841 _young_list(new YoungList(this)),
1842 _gc_time_stamp(0),
1843 _surviving_young_words(NULL),
1844 _full_collections_completed(0),
1845 _in_cset_fast_test(NULL),
1846 _in_cset_fast_test_base(NULL),
1847 _dirty_cards_region_list(NULL) {
1848 _g1h = this; // To catch bugs.
1849 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1850 vm_exit_during_initialization("Failed necessary allocation.");
1851 }
1852
1853 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1854
1855 int n_queues = MAX2((int)ParallelGCThreads, 1);
1856 _task_queues = new RefToScanQueueSet(n_queues);
1857
1858 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1859 assert(n_rem_sets > 0, "Invariant.");
1860
1861 HeapRegionRemSetIterator** iter_arr =
1862 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1863 for (int i = 0; i < n_queues; i++) {
1864 iter_arr[i] = new HeapRegionRemSetIterator();
1865 }
1866 _rem_set_iterator = iter_arr;
1867
1868 for (int i = 0; i < n_queues; i++) {
1869 RefToScanQueue* q = new RefToScanQueue();
1870 q->initialize();
1871 _task_queues->register_queue(i, q);
1872 }
1873
1874 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1875 _gc_alloc_regions[ap] = NULL;
1876 _gc_alloc_region_counts[ap] = 0;
1877 _retained_gc_alloc_regions[ap] = NULL;
1878 // by default, we do not retain a GC alloc region for each ap;
1879 // we'll override this, when appropriate, below
1880 _retain_gc_alloc_region[ap] = false;
1881 }
1882
1883 // We will try to remember the last half-full tenured region we
1884 // allocated to at the end of a collection so that we can re-use it
1885 // during the next collection.
1886 _retain_gc_alloc_region[GCAllocForTenured] = true;
1887
1888 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1889 }
1890
1891 jint G1CollectedHeap::initialize() {
1892 CollectedHeap::pre_initialize();
1893 os::enable_vtime();
1894
1895 // Necessary to satisfy locking discipline assertions.
1896
1897 MutexLocker x(Heap_lock);
1898
1899 // We have to initialize the printer before committing the heap, as
1900 // it will be used then.
1901 _hr_printer.set_active(G1PrintHeapRegions);
1902
1903 // While there are no constraints in the GC code that HeapWordSize
1904 // be any particular value, there are multiple other areas in the
1905 // system which believe this to be true (e.g. oop->object_size in some
1906 // cases incorrectly returns the size in wordSize units rather than
1907 // HeapWordSize).
1908 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1909
1910 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1911 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1912
1913 // Ensure that the sizes are properly aligned.
1914 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1915 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1916
1917 _cg1r = new ConcurrentG1Refine();
1918
1919 // Reserve the maximum.
1920 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1921 // Includes the perm-gen.
1922
1923 // When compressed oops are enabled, the preferred heap base
1924 // is calculated by subtracting the requested size from the
1925 // 32Gb boundary and using the result as the base address for
1926 // heap reservation. If the requested size is not aligned to
1927 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1928 // into the ReservedHeapSpace constructor) then the actual
1929 // base of the reserved heap may end up differing from the
1930 // address that was requested (i.e. the preferred heap base).
1931 // If this happens then we could end up using a non-optimal
1932 // compressed oops mode.
1933
1934 // Since max_byte_size is aligned to the size of a heap region (checked
1935 // above), we also need to align the perm gen size as it might not be.
1936 const size_t total_reserved = max_byte_size +
1937 align_size_up(pgs->max_size(), HeapRegion::GrainBytes);
1938 Universe::check_alignment(total_reserved, HeapRegion::GrainBytes, "g1 heap and perm");
1939
1940 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1941
1942 ReservedHeapSpace heap_rs(total_reserved, HeapRegion::GrainBytes,
1943 UseLargePages, addr);
1944
1945 if (UseCompressedOops) {
1946 if (addr != NULL && !heap_rs.is_reserved()) {
1947 // Failed to reserve at specified address - the requested memory
1948 // region is taken already, for example, by 'java' launcher.
1949 // Try again to reserver heap higher.
1950 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1951
1952 ReservedHeapSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1953 UseLargePages, addr);
1954
1955 if (addr != NULL && !heap_rs0.is_reserved()) {
1956 // Failed to reserve at specified address again - give up.
1957 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1958 assert(addr == NULL, "");
1959
1960 ReservedHeapSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1961 UseLargePages, addr);
1962 heap_rs = heap_rs1;
1963 } else {
1964 heap_rs = heap_rs0;
1965 }
1966 }
1967 }
1968
1969 if (!heap_rs.is_reserved()) {
1970 vm_exit_during_initialization("Could not reserve enough space for object heap");
1971 return JNI_ENOMEM;
1972 }
1973
1974 // It is important to do this in a way such that concurrent readers can't
1975 // temporarily think somethings in the heap. (I've actually seen this
1976 // happen in asserts: DLD.)
1977 _reserved.set_word_size(0);
1978 _reserved.set_start((HeapWord*)heap_rs.base());
1979 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1980
1981 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1982
1983 // Create the gen rem set (and barrier set) for the entire reserved region.
1984 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1985 set_barrier_set(rem_set()->bs());
1986 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1987 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1988 } else {
1989 vm_exit_during_initialization("G1 requires a mod ref bs.");
1990 return JNI_ENOMEM;
1991 }
1992
1993 // Also create a G1 rem set.
1994 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1995 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1996 } else {
1997 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1998 return JNI_ENOMEM;
1999 }
2000
2001 // Carve out the G1 part of the heap.
2002
2003 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2004 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2005 g1_rs.size()/HeapWordSize);
2006 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
2007
2008 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
2009
2010 _g1_storage.initialize(g1_rs, 0);
2011 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2012 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2013 (HeapWord*) _g1_reserved.end(),
2014 _expansion_regions);
2015
2016 // 6843694 - ensure that the maximum region index can fit
2017 // in the remembered set structures.
2018 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2019 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2020
2021 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2022 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2023 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
2024 "too many cards per region");
2025
2026 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
2027
2028 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2029 heap_word_size(init_byte_size));
2030
2031 _g1h = this;
2032
2033 _in_cset_fast_test_length = max_regions();
2034 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
2035
2036 // We're biasing _in_cset_fast_test to avoid subtracting the
2037 // beginning of the heap every time we want to index; basically
2038 // it's the same with what we do with the card table.
2039 _in_cset_fast_test = _in_cset_fast_test_base -
2040 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
2041
2042 // Clear the _cset_fast_test bitmap in anticipation of adding
2043 // regions to the incremental collection set for the first
2044 // evacuation pause.
2045 clear_cset_fast_test();
2046
2047 // Create the ConcurrentMark data structure and thread.
2048 // (Must do this late, so that "max_regions" is defined.)
2049 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
2050 _cmThread = _cm->cmThread();
2051
2052 // Initialize the from_card cache structure of HeapRegionRemSet.
2053 HeapRegionRemSet::init_heap(max_regions());
2054
2055 // Now expand into the initial heap size.
2056 if (!expand(init_byte_size)) {
2057 vm_exit_during_initialization("Failed to allocate initial heap.");
2058 return JNI_ENOMEM;
2059 }
2060
2061 // Perform any initialization actions delegated to the policy.
2062 g1_policy()->init();
2063
2064 g1_policy()->note_start_of_mark_thread();
2065
2066 _refine_cte_cl =
2067 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
2068 g1_rem_set(),
2069 concurrent_g1_refine());
2070 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
2071
2072 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2073 SATB_Q_FL_lock,
2074 G1SATBProcessCompletedThreshold,
2075 Shared_SATB_Q_lock);
2076
2077 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2078 DirtyCardQ_FL_lock,
2079 concurrent_g1_refine()->yellow_zone(),
2080 concurrent_g1_refine()->red_zone(),
2081 Shared_DirtyCardQ_lock);
2082
2083 if (G1DeferredRSUpdate) {
2084 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
2085 DirtyCardQ_FL_lock,
2086 -1, // never trigger processing
2087 -1, // no limit on length
2088 Shared_DirtyCardQ_lock,
2089 &JavaThread::dirty_card_queue_set());
2090 }
2091
2092 // Initialize the card queue set used to hold cards containing
2093 // references into the collection set.
2094 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
2095 DirtyCardQ_FL_lock,
2096 -1, // never trigger processing
2097 -1, // no limit on length
2098 Shared_DirtyCardQ_lock,
2099 &JavaThread::dirty_card_queue_set());
2100
2101 // In case we're keeping closure specialization stats, initialize those
2102 // counts and that mechanism.
2103 SpecializationStats::clear();
2104
2105 _gc_alloc_region_list = NULL;
2106
2107 // Do later initialization work for concurrent refinement.
2108 _cg1r->init();
2109
2110 // Here we allocate the dummy full region that is required by the
2111 // G1AllocRegion class. If we don't pass an address in the reserved
2112 // space here, lots of asserts fire.
2113
2114 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2115 _g1_reserved.start());
2116 // We'll re-use the same region whether the alloc region will
2117 // require BOT updates or not and, if it doesn't, then a non-young
2118 // region will complain that it cannot support allocations without
2119 // BOT updates. So we'll tag the dummy region as young to avoid that.
2120 dummy_region->set_young();
2121 // Make sure it's full.
2122 dummy_region->set_top(dummy_region->end());
2123 G1AllocRegion::setup(this, dummy_region);
2124
2125 init_mutator_alloc_region();
2126
2127 // Do create of the monitoring and management support so that
2128 // values in the heap have been properly initialized.
2129 _g1mm = new G1MonitoringSupport(this, &_g1_storage);
2130
2131 return JNI_OK;
2132 }
2133
2134 void G1CollectedHeap::ref_processing_init() {
2135 // Reference processing in G1 currently works as follows:
2136 //
2137 // * There are two reference processor instances. One is
2138 // used to record and process discovered references
2139 // during concurrent marking; the other is used to
2140 // record and process references during STW pauses
2141 // (both full and incremental).
2142 // * Both ref processors need to 'span' the entire heap as
2143 // the regions in the collection set may be dotted around.
2144 //
2145 // * For the concurrent marking ref processor:
2146 // * Reference discovery is enabled at initial marking.
2147 // * Reference discovery is disabled and the discovered
2148 // references processed etc during remarking.
2149 // * Reference discovery is MT (see below).
2150 // * Reference discovery requires a barrier (see below).
2151 // * Reference processing may or may not be MT
2152 // (depending on the value of ParallelRefProcEnabled
2153 // and ParallelGCThreads).
2154 // * A full GC disables reference discovery by the CM
2155 // ref processor and abandons any entries on it's
2156 // discovered lists.
2157 //
2158 // * For the STW processor:
2159 // * Non MT discovery is enabled at the start of a full GC.
2160 // * Processing and enqueueing during a full GC is non-MT.
2161 // * During a full GC, references are processed after marking.
2162 //
2163 // * Discovery (may or may not be MT) is enabled at the start
2164 // of an incremental evacuation pause.
2165 // * References are processed near the end of a STW evacuation pause.
2166 // * For both types of GC:
2167 // * Discovery is atomic - i.e. not concurrent.
2168 // * Reference discovery will not need a barrier.
2169
2170 SharedHeap::ref_processing_init();
2171 MemRegion mr = reserved_region();
2172
2173 // Concurrent Mark ref processor
2174 _ref_processor_cm =
2175 new ReferenceProcessor(mr, // span
2176 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2177 // mt processing
2178 (int) ParallelGCThreads,
2179 // degree of mt processing
2180 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2181 // mt discovery
2182 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2183 // degree of mt discovery
2184 false,
2185 // Reference discovery is not atomic
2186 &_is_alive_closure_cm,
2187 // is alive closure for efficiency
2188 true);
2189 // Setting next fields of discovered
2190 // lists requires a barrier.
2191
2192 // STW ref processor
2193 _ref_processor_stw =
2194 new ReferenceProcessor(mr, // span
2195 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2196 // mt processing
2197 MAX2((int)ParallelGCThreads, 1),
2198 // degree of mt processing
2199 (ParallelGCThreads > 1),
2200 // mt discovery
2201 MAX2((int)ParallelGCThreads, 1),
2202 // degree of mt discovery
2203 true,
2204 // Reference discovery is atomic
2205 &_is_alive_closure_stw,
2206 // is alive closure for efficiency
2207 false);
2208 // Setting next fields of discovered
2209 // lists requires a barrier.
2210 }
2211
2212 size_t G1CollectedHeap::capacity() const {
2213 return _g1_committed.byte_size();
2214 }
2215
2216 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2217 DirtyCardQueue* into_cset_dcq,
2218 bool concurrent,
2219 int worker_i) {
2220 // Clean cards in the hot card cache
2221 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2222
2223 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2224 int n_completed_buffers = 0;
2225 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2226 n_completed_buffers++;
2227 }
2228 g1_policy()->record_update_rs_processed_buffers(worker_i,
2229 (double) n_completed_buffers);
2230 dcqs.clear_n_completed_buffers();
2231 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2232 }
2233
2234
2235 // Computes the sum of the storage used by the various regions.
2236
2237 size_t G1CollectedHeap::used() const {
2238 assert(Heap_lock->owner() != NULL,
2239 "Should be owned on this thread's behalf.");
2240 size_t result = _summary_bytes_used;
2241 // Read only once in case it is set to NULL concurrently
2242 HeapRegion* hr = _mutator_alloc_region.get();
2243 if (hr != NULL)
2244 result += hr->used();
2245 return result;
2246 }
2247
2248 size_t G1CollectedHeap::used_unlocked() const {
2249 size_t result = _summary_bytes_used;
2250 return result;
2251 }
2252
2253 class SumUsedClosure: public HeapRegionClosure {
2254 size_t _used;
2255 public:
2256 SumUsedClosure() : _used(0) {}
2257 bool doHeapRegion(HeapRegion* r) {
2258 if (!r->continuesHumongous()) {
2259 _used += r->used();
2260 }
2261 return false;
2262 }
2263 size_t result() { return _used; }
2264 };
2265
2266 size_t G1CollectedHeap::recalculate_used() const {
2267 SumUsedClosure blk;
2268 heap_region_iterate(&blk);
2269 return blk.result();
2270 }
2271
2272 #ifndef PRODUCT
2273 class SumUsedRegionsClosure: public HeapRegionClosure {
2274 size_t _num;
2275 public:
2276 SumUsedRegionsClosure() : _num(0) {}
2277 bool doHeapRegion(HeapRegion* r) {
2278 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
2279 _num += 1;
2280 }
2281 return false;
2282 }
2283 size_t result() { return _num; }
2284 };
2285
2286 size_t G1CollectedHeap::recalculate_used_regions() const {
2287 SumUsedRegionsClosure blk;
2288 heap_region_iterate(&blk);
2289 return blk.result();
2290 }
2291 #endif // PRODUCT
2292
2293 size_t G1CollectedHeap::unsafe_max_alloc() {
2294 if (free_regions() > 0) return HeapRegion::GrainBytes;
2295 // otherwise, is there space in the current allocation region?
2296
2297 // We need to store the current allocation region in a local variable
2298 // here. The problem is that this method doesn't take any locks and
2299 // there may be other threads which overwrite the current allocation
2300 // region field. attempt_allocation(), for example, sets it to NULL
2301 // and this can happen *after* the NULL check here but before the call
2302 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2303 // to be a problem in the optimized build, since the two loads of the
2304 // current allocation region field are optimized away.
2305 HeapRegion* hr = _mutator_alloc_region.get();
2306 if (hr == NULL) {
2307 return 0;
2308 }
2309 return hr->free();
2310 }
2311
2312 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2313 return
2314 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2315 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2316 }
2317
2318 #ifndef PRODUCT
2319 void G1CollectedHeap::allocate_dummy_regions() {
2320 // Let's fill up most of the region
2321 size_t word_size = HeapRegion::GrainWords - 1024;
2322 // And as a result the region we'll allocate will be humongous.
2323 guarantee(isHumongous(word_size), "sanity");
2324
2325 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2326 // Let's use the existing mechanism for the allocation
2327 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2328 if (dummy_obj != NULL) {
2329 MemRegion mr(dummy_obj, word_size);
2330 CollectedHeap::fill_with_object(mr);
2331 } else {
2332 // If we can't allocate once, we probably cannot allocate
2333 // again. Let's get out of the loop.
2334 break;
2335 }
2336 }
2337 }
2338 #endif // !PRODUCT
2339
2340 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2341 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2342
2343 // We assume that if concurrent == true, then the caller is a
2344 // concurrent thread that was joined the Suspendible Thread
2345 // Set. If there's ever a cheap way to check this, we should add an
2346 // assert here.
2347
2348 // We have already incremented _total_full_collections at the start
2349 // of the GC, so total_full_collections() represents how many full
2350 // collections have been started.
2351 unsigned int full_collections_started = total_full_collections();
2352
2353 // Given that this method is called at the end of a Full GC or of a
2354 // concurrent cycle, and those can be nested (i.e., a Full GC can
2355 // interrupt a concurrent cycle), the number of full collections
2356 // completed should be either one (in the case where there was no
2357 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2358 // behind the number of full collections started.
2359
2360 // This is the case for the inner caller, i.e. a Full GC.
2361 assert(concurrent ||
2362 (full_collections_started == _full_collections_completed + 1) ||
2363 (full_collections_started == _full_collections_completed + 2),
2364 err_msg("for inner caller (Full GC): full_collections_started = %u "
2365 "is inconsistent with _full_collections_completed = %u",
2366 full_collections_started, _full_collections_completed));
2367
2368 // This is the case for the outer caller, i.e. the concurrent cycle.
2369 assert(!concurrent ||
2370 (full_collections_started == _full_collections_completed + 1),
2371 err_msg("for outer caller (concurrent cycle): "
2372 "full_collections_started = %u "
2373 "is inconsistent with _full_collections_completed = %u",
2374 full_collections_started, _full_collections_completed));
2375
2376 _full_collections_completed += 1;
2377
2378 // We need to clear the "in_progress" flag in the CM thread before
2379 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2380 // is set) so that if a waiter requests another System.gc() it doesn't
2381 // incorrectly see that a marking cyle is still in progress.
2382 if (concurrent) {
2383 _cmThread->clear_in_progress();
2384 }
2385
2386 // This notify_all() will ensure that a thread that called
2387 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2388 // and it's waiting for a full GC to finish will be woken up. It is
2389 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2390 FullGCCount_lock->notify_all();
2391 }
2392
2393 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2394 assert_at_safepoint(true /* should_be_vm_thread */);
2395 GCCauseSetter gcs(this, cause);
2396 switch (cause) {
2397 case GCCause::_heap_inspection:
2398 case GCCause::_heap_dump: {
2399 HandleMark hm;
2400 do_full_collection(false); // don't clear all soft refs
2401 break;
2402 }
2403 default: // XXX FIX ME
2404 ShouldNotReachHere(); // Unexpected use of this function
2405 }
2406 }
2407
2408 void G1CollectedHeap::collect(GCCause::Cause cause) {
2409 // The caller doesn't have the Heap_lock
2410 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2411
2412 unsigned int gc_count_before;
2413 unsigned int full_gc_count_before;
2414 {
2415 MutexLocker ml(Heap_lock);
2416
2417 // Read the GC count while holding the Heap_lock
2418 gc_count_before = SharedHeap::heap()->total_collections();
2419 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2420 }
2421
2422 if (should_do_concurrent_full_gc(cause)) {
2423 // Schedule an initial-mark evacuation pause that will start a
2424 // concurrent cycle. We're setting word_size to 0 which means that
2425 // we are not requesting a post-GC allocation.
2426 VM_G1IncCollectionPause op(gc_count_before,
2427 0, /* word_size */
2428 true, /* should_initiate_conc_mark */
2429 g1_policy()->max_pause_time_ms(),
2430 cause);
2431 VMThread::execute(&op);
2432 } else {
2433 if (cause == GCCause::_gc_locker
2434 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2435
2436 // Schedule a standard evacuation pause. We're setting word_size
2437 // to 0 which means that we are not requesting a post-GC allocation.
2438 VM_G1IncCollectionPause op(gc_count_before,
2439 0, /* word_size */
2440 false, /* should_initiate_conc_mark */
2441 g1_policy()->max_pause_time_ms(),
2442 cause);
2443 VMThread::execute(&op);
2444 } else {
2445 // Schedule a Full GC.
2446 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2447 VMThread::execute(&op);
2448 }
2449 }
2450 }
2451
2452 bool G1CollectedHeap::is_in(const void* p) const {
2453 HeapRegion* hr = _hrs.addr_to_region((HeapWord*) p);
2454 if (hr != NULL) {
2455 return hr->is_in(p);
2456 } else {
2457 return _perm_gen->as_gen()->is_in(p);
2458 }
2459 }
2460
2461 // Iteration functions.
2462
2463 // Iterates an OopClosure over all ref-containing fields of objects
2464 // within a HeapRegion.
2465
2466 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2467 MemRegion _mr;
2468 OopClosure* _cl;
2469 public:
2470 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2471 : _mr(mr), _cl(cl) {}
2472 bool doHeapRegion(HeapRegion* r) {
2473 if (! r->continuesHumongous()) {
2474 r->oop_iterate(_cl);
2475 }
2476 return false;
2477 }
2478 };
2479
2480 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2481 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2482 heap_region_iterate(&blk);
2483 if (do_perm) {
2484 perm_gen()->oop_iterate(cl);
2485 }
2486 }
2487
2488 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2489 IterateOopClosureRegionClosure blk(mr, cl);
2490 heap_region_iterate(&blk);
2491 if (do_perm) {
2492 perm_gen()->oop_iterate(cl);
2493 }
2494 }
2495
2496 // Iterates an ObjectClosure over all objects within a HeapRegion.
2497
2498 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2499 ObjectClosure* _cl;
2500 public:
2501 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2502 bool doHeapRegion(HeapRegion* r) {
2503 if (! r->continuesHumongous()) {
2504 r->object_iterate(_cl);
2505 }
2506 return false;
2507 }
2508 };
2509
2510 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2511 IterateObjectClosureRegionClosure blk(cl);
2512 heap_region_iterate(&blk);
2513 if (do_perm) {
2514 perm_gen()->object_iterate(cl);
2515 }
2516 }
2517
2518 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2519 // FIXME: is this right?
2520 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2521 }
2522
2523 // Calls a SpaceClosure on a HeapRegion.
2524
2525 class SpaceClosureRegionClosure: public HeapRegionClosure {
2526 SpaceClosure* _cl;
2527 public:
2528 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2529 bool doHeapRegion(HeapRegion* r) {
2530 _cl->do_space(r);
2531 return false;
2532 }
2533 };
2534
2535 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2536 SpaceClosureRegionClosure blk(cl);
2537 heap_region_iterate(&blk);
2538 }
2539
2540 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2541 _hrs.iterate(cl);
2542 }
2543
2544 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2545 HeapRegionClosure* cl) const {
2546 _hrs.iterate_from(r, cl);
2547 }
2548
2549 void
2550 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2551 int worker,
2552 jint claim_value) {
2553 const size_t regions = n_regions();
2554 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
2555 // try to spread out the starting points of the workers
2556 const size_t start_index = regions / worker_num * (size_t) worker;
2557
2558 // each worker will actually look at all regions
2559 for (size_t count = 0; count < regions; ++count) {
2560 const size_t index = (start_index + count) % regions;
2561 assert(0 <= index && index < regions, "sanity");
2562 HeapRegion* r = region_at(index);
2563 // we'll ignore "continues humongous" regions (we'll process them
2564 // when we come across their corresponding "start humongous"
2565 // region) and regions already claimed
2566 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2567 continue;
2568 }
2569 // OK, try to claim it
2570 if (r->claimHeapRegion(claim_value)) {
2571 // success!
2572 assert(!r->continuesHumongous(), "sanity");
2573 if (r->startsHumongous()) {
2574 // If the region is "starts humongous" we'll iterate over its
2575 // "continues humongous" first; in fact we'll do them
2576 // first. The order is important. In on case, calling the
2577 // closure on the "starts humongous" region might de-allocate
2578 // and clear all its "continues humongous" regions and, as a
2579 // result, we might end up processing them twice. So, we'll do
2580 // them first (notice: most closures will ignore them anyway) and
2581 // then we'll do the "starts humongous" region.
2582 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2583 HeapRegion* chr = region_at(ch_index);
2584
2585 // if the region has already been claimed or it's not
2586 // "continues humongous" we're done
2587 if (chr->claim_value() == claim_value ||
2588 !chr->continuesHumongous()) {
2589 break;
2590 }
2591
2592 // Noone should have claimed it directly. We can given
2593 // that we claimed its "starts humongous" region.
2594 assert(chr->claim_value() != claim_value, "sanity");
2595 assert(chr->humongous_start_region() == r, "sanity");
2596
2597 if (chr->claimHeapRegion(claim_value)) {
2598 // we should always be able to claim it; noone else should
2599 // be trying to claim this region
2600
2601 bool res2 = cl->doHeapRegion(chr);
2602 assert(!res2, "Should not abort");
2603
2604 // Right now, this holds (i.e., no closure that actually
2605 // does something with "continues humongous" regions
2606 // clears them). We might have to weaken it in the future,
2607 // but let's leave these two asserts here for extra safety.
2608 assert(chr->continuesHumongous(), "should still be the case");
2609 assert(chr->humongous_start_region() == r, "sanity");
2610 } else {
2611 guarantee(false, "we should not reach here");
2612 }
2613 }
2614 }
2615
2616 assert(!r->continuesHumongous(), "sanity");
2617 bool res = cl->doHeapRegion(r);
2618 assert(!res, "Should not abort");
2619 }
2620 }
2621 }
2622
2623 class ResetClaimValuesClosure: public HeapRegionClosure {
2624 public:
2625 bool doHeapRegion(HeapRegion* r) {
2626 r->set_claim_value(HeapRegion::InitialClaimValue);
2627 return false;
2628 }
2629 };
2630
2631 void
2632 G1CollectedHeap::reset_heap_region_claim_values() {
2633 ResetClaimValuesClosure blk;
2634 heap_region_iterate(&blk);
2635 }
2636
2637 #ifdef ASSERT
2638 // This checks whether all regions in the heap have the correct claim
2639 // value. I also piggy-backed on this a check to ensure that the
2640 // humongous_start_region() information on "continues humongous"
2641 // regions is correct.
2642
2643 class CheckClaimValuesClosure : public HeapRegionClosure {
2644 private:
2645 jint _claim_value;
2646 size_t _failures;
2647 HeapRegion* _sh_region;
2648 public:
2649 CheckClaimValuesClosure(jint claim_value) :
2650 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2651 bool doHeapRegion(HeapRegion* r) {
2652 if (r->claim_value() != _claim_value) {
2653 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2654 "claim value = %d, should be %d",
2655 r->bottom(), r->end(), r->claim_value(),
2656 _claim_value);
2657 ++_failures;
2658 }
2659 if (!r->isHumongous()) {
2660 _sh_region = NULL;
2661 } else if (r->startsHumongous()) {
2662 _sh_region = r;
2663 } else if (r->continuesHumongous()) {
2664 if (r->humongous_start_region() != _sh_region) {
2665 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2666 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2667 r->bottom(), r->end(),
2668 r->humongous_start_region(),
2669 _sh_region);
2670 ++_failures;
2671 }
2672 }
2673 return false;
2674 }
2675 size_t failures() {
2676 return _failures;
2677 }
2678 };
2679
2680 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2681 CheckClaimValuesClosure cl(claim_value);
2682 heap_region_iterate(&cl);
2683 return cl.failures() == 0;
2684 }
2685 #endif // ASSERT
2686
2687 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2688 HeapRegion* r = g1_policy()->collection_set();
2689 while (r != NULL) {
2690 HeapRegion* next = r->next_in_collection_set();
2691 if (cl->doHeapRegion(r)) {
2692 cl->incomplete();
2693 return;
2694 }
2695 r = next;
2696 }
2697 }
2698
2699 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2700 HeapRegionClosure *cl) {
2701 if (r == NULL) {
2702 // The CSet is empty so there's nothing to do.
2703 return;
2704 }
2705
2706 assert(r->in_collection_set(),
2707 "Start region must be a member of the collection set.");
2708 HeapRegion* cur = r;
2709 while (cur != NULL) {
2710 HeapRegion* next = cur->next_in_collection_set();
2711 if (cl->doHeapRegion(cur) && false) {
2712 cl->incomplete();
2713 return;
2714 }
2715 cur = next;
2716 }
2717 cur = g1_policy()->collection_set();
2718 while (cur != r) {
2719 HeapRegion* next = cur->next_in_collection_set();
2720 if (cl->doHeapRegion(cur) && false) {
2721 cl->incomplete();
2722 return;
2723 }
2724 cur = next;
2725 }
2726 }
2727
2728 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2729 return n_regions() > 0 ? region_at(0) : NULL;
2730 }
2731
2732
2733 Space* G1CollectedHeap::space_containing(const void* addr) const {
2734 Space* res = heap_region_containing(addr);
2735 if (res == NULL)
2736 res = perm_gen()->space_containing(addr);
2737 return res;
2738 }
2739
2740 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2741 Space* sp = space_containing(addr);
2742 if (sp != NULL) {
2743 return sp->block_start(addr);
2744 }
2745 return NULL;
2746 }
2747
2748 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2749 Space* sp = space_containing(addr);
2750 assert(sp != NULL, "block_size of address outside of heap");
2751 return sp->block_size(addr);
2752 }
2753
2754 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2755 Space* sp = space_containing(addr);
2756 return sp->block_is_obj(addr);
2757 }
2758
2759 bool G1CollectedHeap::supports_tlab_allocation() const {
2760 return true;
2761 }
2762
2763 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2764 return HeapRegion::GrainBytes;
2765 }
2766
2767 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2768 // Return the remaining space in the cur alloc region, but not less than
2769 // the min TLAB size.
2770
2771 // Also, this value can be at most the humongous object threshold,
2772 // since we can't allow tlabs to grow big enough to accomodate
2773 // humongous objects.
2774
2775 HeapRegion* hr = _mutator_alloc_region.get();
2776 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2777 if (hr == NULL) {
2778 return max_tlab_size;
2779 } else {
2780 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2781 }
2782 }
2783
2784 size_t G1CollectedHeap::max_capacity() const {
2785 return _g1_reserved.byte_size();
2786 }
2787
2788 jlong G1CollectedHeap::millis_since_last_gc() {
2789 // assert(false, "NYI");
2790 return 0;
2791 }
2792
2793 void G1CollectedHeap::prepare_for_verify() {
2794 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2795 ensure_parsability(false);
2796 }
2797 g1_rem_set()->prepare_for_verify();
2798 }
2799
2800 class VerifyLivenessOopClosure: public OopClosure {
2801 G1CollectedHeap* _g1h;
2802 VerifyOption _vo;
2803 public:
2804 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2805 _g1h(g1h), _vo(vo)
2806 { }
2807 void do_oop(narrowOop *p) { do_oop_work(p); }
2808 void do_oop( oop *p) { do_oop_work(p); }
2809
2810 template <class T> void do_oop_work(T *p) {
2811 oop obj = oopDesc::load_decode_heap_oop(p);
2812 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2813 "Dead object referenced by a not dead object");
2814 }
2815 };
2816
2817 class VerifyObjsInRegionClosure: public ObjectClosure {
2818 private:
2819 G1CollectedHeap* _g1h;
2820 size_t _live_bytes;
2821 HeapRegion *_hr;
2822 VerifyOption _vo;
2823 public:
2824 // _vo == UsePrevMarking -> use "prev" marking information,
2825 // _vo == UseNextMarking -> use "next" marking information,
2826 // _vo == UseMarkWord -> use mark word from object header.
2827 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2828 : _live_bytes(0), _hr(hr), _vo(vo) {
2829 _g1h = G1CollectedHeap::heap();
2830 }
2831 void do_object(oop o) {
2832 VerifyLivenessOopClosure isLive(_g1h, _vo);
2833 assert(o != NULL, "Huh?");
2834 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2835 // If the object is alive according to the mark word,
2836 // then verify that the marking information agrees.
2837 // Note we can't verify the contra-positive of the
2838 // above: if the object is dead (according to the mark
2839 // word), it may not be marked, or may have been marked
2840 // but has since became dead, or may have been allocated
2841 // since the last marking.
2842 if (_vo == VerifyOption_G1UseMarkWord) {
2843 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2844 }
2845
2846 o->oop_iterate(&isLive);
2847 if (!_hr->obj_allocated_since_prev_marking(o)) {
2848 size_t obj_size = o->size(); // Make sure we don't overflow
2849 _live_bytes += (obj_size * HeapWordSize);
2850 }
2851 }
2852 }
2853 size_t live_bytes() { return _live_bytes; }
2854 };
2855
2856 class PrintObjsInRegionClosure : public ObjectClosure {
2857 HeapRegion *_hr;
2858 G1CollectedHeap *_g1;
2859 public:
2860 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2861 _g1 = G1CollectedHeap::heap();
2862 };
2863
2864 void do_object(oop o) {
2865 if (o != NULL) {
2866 HeapWord *start = (HeapWord *) o;
2867 size_t word_sz = o->size();
2868 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2869 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2870 (void*) o, word_sz,
2871 _g1->isMarkedPrev(o),
2872 _g1->isMarkedNext(o),
2873 _hr->obj_allocated_since_prev_marking(o));
2874 HeapWord *end = start + word_sz;
2875 HeapWord *cur;
2876 int *val;
2877 for (cur = start; cur < end; cur++) {
2878 val = (int *) cur;
2879 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2880 }
2881 }
2882 }
2883 };
2884
2885 class VerifyRegionClosure: public HeapRegionClosure {
2886 private:
2887 bool _allow_dirty;
2888 bool _par;
2889 VerifyOption _vo;
2890 bool _failures;
2891 public:
2892 // _vo == UsePrevMarking -> use "prev" marking information,
2893 // _vo == UseNextMarking -> use "next" marking information,
2894 // _vo == UseMarkWord -> use mark word from object header.
2895 VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
2896 : _allow_dirty(allow_dirty),
2897 _par(par),
2898 _vo(vo),
2899 _failures(false) {}
2900
2901 bool failures() {
2902 return _failures;
2903 }
2904
2905 bool doHeapRegion(HeapRegion* r) {
2906 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2907 "Should be unclaimed at verify points.");
2908 if (!r->continuesHumongous()) {
2909 bool failures = false;
2910 r->verify(_allow_dirty, _vo, &failures);
2911 if (failures) {
2912 _failures = true;
2913 } else {
2914 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2915 r->object_iterate(¬_dead_yet_cl);
2916 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2917 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2918 "max_live_bytes "SIZE_FORMAT" "
2919 "< calculated "SIZE_FORMAT,
2920 r->bottom(), r->end(),
2921 r->max_live_bytes(),
2922 not_dead_yet_cl.live_bytes());
2923 _failures = true;
2924 }
2925 }
2926 }
2927 return false; // stop the region iteration if we hit a failure
2928 }
2929 };
2930
2931 class VerifyRootsClosure: public OopsInGenClosure {
2932 private:
2933 G1CollectedHeap* _g1h;
2934 VerifyOption _vo;
2935 bool _failures;
2936 public:
2937 // _vo == UsePrevMarking -> use "prev" marking information,
2938 // _vo == UseNextMarking -> use "next" marking information,
2939 // _vo == UseMarkWord -> use mark word from object header.
2940 VerifyRootsClosure(VerifyOption vo) :
2941 _g1h(G1CollectedHeap::heap()),
2942 _vo(vo),
2943 _failures(false) { }
2944
2945 bool failures() { return _failures; }
2946
2947 template <class T> void do_oop_nv(T* p) {
2948 T heap_oop = oopDesc::load_heap_oop(p);
2949 if (!oopDesc::is_null(heap_oop)) {
2950 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2951 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2952 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2953 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2954 if (_vo == VerifyOption_G1UseMarkWord) {
2955 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2956 }
2957 obj->print_on(gclog_or_tty);
2958 _failures = true;
2959 }
2960 }
2961 }
2962
2963 void do_oop(oop* p) { do_oop_nv(p); }
2964 void do_oop(narrowOop* p) { do_oop_nv(p); }
2965 };
2966
2967 // This is the task used for parallel heap verification.
2968
2969 class G1ParVerifyTask: public AbstractGangTask {
2970 private:
2971 G1CollectedHeap* _g1h;
2972 bool _allow_dirty;
2973 VerifyOption _vo;
2974 bool _failures;
2975
2976 public:
2977 // _vo == UsePrevMarking -> use "prev" marking information,
2978 // _vo == UseNextMarking -> use "next" marking information,
2979 // _vo == UseMarkWord -> use mark word from object header.
2980 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
2981 AbstractGangTask("Parallel verify task"),
2982 _g1h(g1h),
2983 _allow_dirty(allow_dirty),
2984 _vo(vo),
2985 _failures(false) { }
2986
2987 bool failures() {
2988 return _failures;
2989 }
2990
2991 void work(int worker_i) {
2992 HandleMark hm;
2993 VerifyRegionClosure blk(_allow_dirty, true, _vo);
2994 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2995 HeapRegion::ParVerifyClaimValue);
2996 if (blk.failures()) {
2997 _failures = true;
2998 }
2999 }
3000 };
3001
3002 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
3003 verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
3004 }
3005
3006 void G1CollectedHeap::verify(bool allow_dirty,
3007 bool silent,
3008 VerifyOption vo) {
3009 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3010 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
3011 VerifyRootsClosure rootsCl(vo);
3012 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
3013
3014 // We apply the relevant closures to all the oops in the
3015 // system dictionary, the string table and the code cache.
3016 const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
3017
3018 process_strong_roots(true, // activate StrongRootsScope
3019 true, // we set "collecting perm gen" to true,
3020 // so we don't reset the dirty cards in the perm gen.
3021 SharedHeap::ScanningOption(so), // roots scanning options
3022 &rootsCl,
3023 &blobsCl,
3024 &rootsCl);
3025
3026 // If we're verifying after the marking phase of a Full GC then we can't
3027 // treat the perm gen as roots into the G1 heap. Some of the objects in
3028 // the perm gen may be dead and hence not marked. If one of these dead
3029 // objects is considered to be a root then we may end up with a false
3030 // "Root location <x> points to dead ob <y>" failure.
3031 if (vo != VerifyOption_G1UseMarkWord) {
3032 // Since we used "collecting_perm_gen" == true above, we will not have
3033 // checked the refs from perm into the G1-collected heap. We check those
3034 // references explicitly below. Whether the relevant cards are dirty
3035 // is checked further below in the rem set verification.
3036 if (!silent) { gclog_or_tty->print("Permgen roots "); }
3037 perm_gen()->oop_iterate(&rootsCl);
3038 }
3039 bool failures = rootsCl.failures();
3040
3041 if (vo != VerifyOption_G1UseMarkWord) {
3042 // If we're verifying during a full GC then the region sets
3043 // will have been torn down at the start of the GC. Therefore
3044 // verifying the region sets will fail. So we only verify
3045 // the region sets when not in a full GC.
3046 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3047 verify_region_sets();
3048 }
3049
3050 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3051 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3052 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3053 "sanity check");
3054
3055 G1ParVerifyTask task(this, allow_dirty, vo);
3056 int n_workers = workers()->total_workers();
3057 set_par_threads(n_workers);
3058 workers()->run_task(&task);
3059 set_par_threads(0);
3060 if (task.failures()) {
3061 failures = true;
3062 }
3063
3064 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3065 "sanity check");
3066
3067 reset_heap_region_claim_values();
3068
3069 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3070 "sanity check");
3071 } else {
3072 VerifyRegionClosure blk(allow_dirty, false, vo);
3073 heap_region_iterate(&blk);
3074 if (blk.failures()) {
3075 failures = true;
3076 }
3077 }
3078 if (!silent) gclog_or_tty->print("RemSet ");
3079 rem_set()->verify();
3080
3081 if (failures) {
3082 gclog_or_tty->print_cr("Heap:");
3083 print_on(gclog_or_tty, true /* extended */);
3084 gclog_or_tty->print_cr("");
3085 #ifndef PRODUCT
3086 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3087 concurrent_mark()->print_reachable("at-verification-failure",
3088 vo, false /* all */);
3089 }
3090 #endif
3091 gclog_or_tty->flush();
3092 }
3093 guarantee(!failures, "there should not have been any failures");
3094 } else {
3095 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
3096 }
3097 }
3098
3099 class PrintRegionClosure: public HeapRegionClosure {
3100 outputStream* _st;
3101 public:
3102 PrintRegionClosure(outputStream* st) : _st(st) {}
3103 bool doHeapRegion(HeapRegion* r) {
3104 r->print_on(_st);
3105 return false;
3106 }
3107 };
3108
3109 void G1CollectedHeap::print() const { print_on(tty); }
3110
3111 void G1CollectedHeap::print_on(outputStream* st) const {
3112 print_on(st, PrintHeapAtGCExtended);
3113 }
3114
3115 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
3116 st->print(" %-20s", "garbage-first heap");
3117 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3118 capacity()/K, used_unlocked()/K);
3119 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3120 _g1_storage.low_boundary(),
3121 _g1_storage.high(),
3122 _g1_storage.high_boundary());
3123 st->cr();
3124 st->print(" region size " SIZE_FORMAT "K, ",
3125 HeapRegion::GrainBytes/K);
3126 size_t young_regions = _young_list->length();
3127 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
3128 young_regions, young_regions * HeapRegion::GrainBytes / K);
3129 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
3130 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
3131 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
3132 st->cr();
3133 perm()->as_gen()->print_on(st);
3134 if (extended) {
3135 st->cr();
3136 print_on_extended(st);
3137 }
3138 }
3139
3140 void G1CollectedHeap::print_on_extended(outputStream* st) const {
3141 PrintRegionClosure blk(st);
3142 heap_region_iterate(&blk);
3143 }
3144
3145 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3146 if (G1CollectedHeap::use_parallel_gc_threads()) {
3147 workers()->print_worker_threads_on(st);
3148 }
3149 _cmThread->print_on(st);
3150 st->cr();
3151 _cm->print_worker_threads_on(st);
3152 _cg1r->print_worker_threads_on(st);
3153 st->cr();
3154 }
3155
3156 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3157 if (G1CollectedHeap::use_parallel_gc_threads()) {
3158 workers()->threads_do(tc);
3159 }
3160 tc->do_thread(_cmThread);
3161 _cg1r->threads_do(tc);
3162 }
3163
3164 void G1CollectedHeap::print_tracing_info() const {
3165 // We'll overload this to mean "trace GC pause statistics."
3166 if (TraceGen0Time || TraceGen1Time) {
3167 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3168 // to that.
3169 g1_policy()->print_tracing_info();
3170 }
3171 if (G1SummarizeRSetStats) {
3172 g1_rem_set()->print_summary_info();
3173 }
3174 if (G1SummarizeConcMark) {
3175 concurrent_mark()->print_summary_info();
3176 }
3177 g1_policy()->print_yg_surv_rate_info();
3178 SpecializationStats::print();
3179 }
3180
3181 #ifndef PRODUCT
3182 // Helpful for debugging RSet issues.
3183
3184 class PrintRSetsClosure : public HeapRegionClosure {
3185 private:
3186 const char* _msg;
3187 size_t _occupied_sum;
3188
3189 public:
3190 bool doHeapRegion(HeapRegion* r) {
3191 HeapRegionRemSet* hrrs = r->rem_set();
3192 size_t occupied = hrrs->occupied();
3193 _occupied_sum += occupied;
3194
3195 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3196 HR_FORMAT_PARAMS(r));
3197 if (occupied == 0) {
3198 gclog_or_tty->print_cr(" RSet is empty");
3199 } else {
3200 hrrs->print();
3201 }
3202 gclog_or_tty->print_cr("----------");
3203 return false;
3204 }
3205
3206 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3207 gclog_or_tty->cr();
3208 gclog_or_tty->print_cr("========================================");
3209 gclog_or_tty->print_cr(msg);
3210 gclog_or_tty->cr();
3211 }
3212
3213 ~PrintRSetsClosure() {
3214 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3215 gclog_or_tty->print_cr("========================================");
3216 gclog_or_tty->cr();
3217 }
3218 };
3219
3220 void G1CollectedHeap::print_cset_rsets() {
3221 PrintRSetsClosure cl("Printing CSet RSets");
3222 collection_set_iterate(&cl);
3223 }
3224
3225 void G1CollectedHeap::print_all_rsets() {
3226 PrintRSetsClosure cl("Printing All RSets");;
3227 heap_region_iterate(&cl);
3228 }
3229 #endif // PRODUCT
3230
3231 G1CollectedHeap* G1CollectedHeap::heap() {
3232 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3233 "not a garbage-first heap");
3234 return _g1h;
3235 }
3236
3237 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3238 // always_do_update_barrier = false;
3239 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3240 // Call allocation profiler
3241 AllocationProfiler::iterate_since_last_gc();
3242 // Fill TLAB's and such
3243 ensure_parsability(true);
3244 }
3245
3246 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3247 // FIXME: what is this about?
3248 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3249 // is set.
3250 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3251 "derived pointer present"));
3252 // always_do_update_barrier = true;
3253
3254 // We have just completed a GC. Update the soft reference
3255 // policy with the new heap occupancy
3256 Universe::update_heap_info_at_gc();
3257 }
3258
3259 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3260 unsigned int gc_count_before,
3261 bool* succeeded) {
3262 assert_heap_not_locked_and_not_at_safepoint();
3263 g1_policy()->record_stop_world_start();
3264 VM_G1IncCollectionPause op(gc_count_before,
3265 word_size,
3266 false, /* should_initiate_conc_mark */
3267 g1_policy()->max_pause_time_ms(),
3268 GCCause::_g1_inc_collection_pause);
3269 VMThread::execute(&op);
3270
3271 HeapWord* result = op.result();
3272 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3273 assert(result == NULL || ret_succeeded,
3274 "the result should be NULL if the VM did not succeed");
3275 *succeeded = ret_succeeded;
3276
3277 assert_heap_not_locked();
3278 return result;
3279 }
3280
3281 void
3282 G1CollectedHeap::doConcurrentMark() {
3283 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3284 if (!_cmThread->in_progress()) {
3285 _cmThread->set_started();
3286 CGC_lock->notify();
3287 }
3288 }
3289
3290 void G1CollectedHeap::do_sync_mark() {
3291 _cm->checkpointRootsInitial();
3292 _cm->markFromRoots();
3293 _cm->checkpointRootsFinal(false);
3294 }
3295
3296 // <NEW PREDICTION>
3297
3298 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3299 bool young) {
3300 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3301 }
3302
3303 void G1CollectedHeap::check_if_region_is_too_expensive(double
3304 predicted_time_ms) {
3305 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3306 }
3307
3308 size_t G1CollectedHeap::pending_card_num() {
3309 size_t extra_cards = 0;
3310 JavaThread *curr = Threads::first();
3311 while (curr != NULL) {
3312 DirtyCardQueue& dcq = curr->dirty_card_queue();
3313 extra_cards += dcq.size();
3314 curr = curr->next();
3315 }
3316 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3317 size_t buffer_size = dcqs.buffer_size();
3318 size_t buffer_num = dcqs.completed_buffers_num();
3319 return buffer_size * buffer_num + extra_cards;
3320 }
3321
3322 size_t G1CollectedHeap::max_pending_card_num() {
3323 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3324 size_t buffer_size = dcqs.buffer_size();
3325 size_t buffer_num = dcqs.completed_buffers_num();
3326 int thread_num = Threads::number_of_threads();
3327 return (buffer_num + thread_num) * buffer_size;
3328 }
3329
3330 size_t G1CollectedHeap::cards_scanned() {
3331 return g1_rem_set()->cardsScanned();
3332 }
3333
3334 void
3335 G1CollectedHeap::setup_surviving_young_words() {
3336 guarantee( _surviving_young_words == NULL, "pre-condition" );
3337 size_t array_length = g1_policy()->young_cset_length();
3338 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3339 if (_surviving_young_words == NULL) {
3340 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3341 "Not enough space for young surv words summary.");
3342 }
3343 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3344 #ifdef ASSERT
3345 for (size_t i = 0; i < array_length; ++i) {
3346 assert( _surviving_young_words[i] == 0, "memset above" );
3347 }
3348 #endif // !ASSERT
3349 }
3350
3351 void
3352 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3353 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3354 size_t array_length = g1_policy()->young_cset_length();
3355 for (size_t i = 0; i < array_length; ++i)
3356 _surviving_young_words[i] += surv_young_words[i];
3357 }
3358
3359 void
3360 G1CollectedHeap::cleanup_surviving_young_words() {
3361 guarantee( _surviving_young_words != NULL, "pre-condition" );
3362 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3363 _surviving_young_words = NULL;
3364 }
3365
3366 // </NEW PREDICTION>
3367
3368 #ifdef ASSERT
3369 class VerifyCSetClosure: public HeapRegionClosure {
3370 public:
3371 bool doHeapRegion(HeapRegion* hr) {
3372 // Here we check that the CSet region's RSet is ready for parallel
3373 // iteration. The fields that we'll verify are only manipulated
3374 // when the region is part of a CSet and is collected. Afterwards,
3375 // we reset these fields when we clear the region's RSet (when the
3376 // region is freed) so they are ready when the region is
3377 // re-allocated. The only exception to this is if there's an
3378 // evacuation failure and instead of freeing the region we leave
3379 // it in the heap. In that case, we reset these fields during
3380 // evacuation failure handling.
3381 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3382
3383 // Here's a good place to add any other checks we'd like to
3384 // perform on CSet regions.
3385 return false;
3386 }
3387 };
3388 #endif // ASSERT
3389
3390 #if TASKQUEUE_STATS
3391 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3392 st->print_raw_cr("GC Task Stats");
3393 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3394 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3395 }
3396
3397 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3398 print_taskqueue_stats_hdr(st);
3399
3400 TaskQueueStats totals;
3401 const int n = workers() != NULL ? workers()->total_workers() : 1;
3402 for (int i = 0; i < n; ++i) {
3403 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3404 totals += task_queue(i)->stats;
3405 }
3406 st->print_raw("tot "); totals.print(st); st->cr();
3407
3408 DEBUG_ONLY(totals.verify());
3409 }
3410
3411 void G1CollectedHeap::reset_taskqueue_stats() {
3412 const int n = workers() != NULL ? workers()->total_workers() : 1;
3413 for (int i = 0; i < n; ++i) {
3414 task_queue(i)->stats.reset();
3415 }
3416 }
3417 #endif // TASKQUEUE_STATS
3418
3419 bool
3420 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3421 assert_at_safepoint(true /* should_be_vm_thread */);
3422 guarantee(!is_gc_active(), "collection is not reentrant");
3423
3424 if (GC_locker::check_active_before_gc()) {
3425 return false;
3426 }
3427
3428 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3429 ResourceMark rm;
3430
3431 if (PrintHeapAtGC) {
3432 Universe::print_heap_before_gc();
3433 }
3434
3435 verify_region_sets_optional();
3436 verify_dirty_young_regions();
3437
3438 {
3439 // This call will decide whether this pause is an initial-mark
3440 // pause. If it is, during_initial_mark_pause() will return true
3441 // for the duration of this pause.
3442 g1_policy()->decide_on_conc_mark_initiation();
3443
3444 char verbose_str[128];
3445 sprintf(verbose_str, "GC pause ");
3446 if (g1_policy()->in_young_gc_mode()) {
3447 if (g1_policy()->full_young_gcs())
3448 strcat(verbose_str, "(young)");
3449 else
3450 strcat(verbose_str, "(partial)");
3451 }
3452 if (g1_policy()->during_initial_mark_pause()) {
3453 strcat(verbose_str, " (initial-mark)");
3454 // We are about to start a marking cycle, so we increment the
3455 // full collection counter.
3456 increment_total_full_collections();
3457 }
3458
3459 // if PrintGCDetails is on, we'll print long statistics information
3460 // in the collector policy code, so let's not print this as the output
3461 // is messy if we do.
3462 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3463 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3464 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3465
3466 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3467 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3468
3469 // If the secondary_free_list is not empty, append it to the
3470 // free_list. No need to wait for the cleanup operation to finish;
3471 // the region allocation code will check the secondary_free_list
3472 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3473 // set, skip this step so that the region allocation code has to
3474 // get entries from the secondary_free_list.
3475 if (!G1StressConcRegionFreeing) {
3476 append_secondary_free_list_if_not_empty_with_lock();
3477 }
3478
3479 increment_gc_time_stamp();
3480
3481 if (g1_policy()->in_young_gc_mode()) {
3482 assert(check_young_list_well_formed(),
3483 "young list should be well formed");
3484 }
3485
3486 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3487 IsGCActiveMark x;
3488
3489 gc_prologue(false);
3490 increment_total_collections(false /* full gc */);
3491
3492 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3493 HandleMark hm; // Discard invalid handles created during verification
3494 gclog_or_tty->print(" VerifyBeforeGC:");
3495 prepare_for_verify();
3496 Universe::verify(/* allow dirty */ false,
3497 /* silent */ false,
3498 /* option */ VerifyOption_G1UsePrevMarking);
3499
3500 }
3501
3502 COMPILER2_PRESENT(DerivedPointerTable::clear());
3503
3504 // Please see comment in g1CollectedHeap.hpp and
3505 // G1CollectedHeap::ref_processing_init() to see how
3506 // reference processing currently works in G1.
3507
3508 assert(!ref_processor_stw()->discovery_enabled(), "Precondition");
3509 ref_processor_stw()->verify_no_references_recorded();
3510
3511 // Enable discovery in the STW reference processor
3512 ref_processor_stw()->enable_discovery();
3513
3514 {
3515 // We want to temporarily turn off discovery by the
3516 // CM ref processor, if necessary, and turn it back on
3517 // on again later if we do. Using a scoped
3518 // NoRefDiscovery object will do this.
3519 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3520
3521 // Forget the current alloc region (we might even choose it to be part
3522 // of the collection set!).
3523 release_mutator_alloc_region();
3524
3525 // We should call this after we retire the mutator alloc
3526 // region(s) so that all the ALLOC / RETIRE events are generated
3527 // before the start GC event.
3528 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3529
3530 // The elapsed time induced by the start time below deliberately elides
3531 // the possible verification above.
3532 double start_time_sec = os::elapsedTime();
3533 size_t start_used_bytes = used();
3534
3535 #if YOUNG_LIST_VERBOSE
3536 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3537 _young_list->print();
3538 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3539 #endif // YOUNG_LIST_VERBOSE
3540
3541 g1_policy()->record_collection_pause_start(start_time_sec,
3542 start_used_bytes);
3543
3544 #if YOUNG_LIST_VERBOSE
3545 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3546 _young_list->print();
3547 #endif // YOUNG_LIST_VERBOSE
3548
3549 if (g1_policy()->during_initial_mark_pause()) {
3550 concurrent_mark()->checkpointRootsInitialPre();
3551 }
3552 save_marks();
3553
3554 // We must do this before any possible evacuation that should propagate
3555 // marks.
3556 if (mark_in_progress()) {
3557 double start_time_sec = os::elapsedTime();
3558
3559 _cm->drainAllSATBBuffers();
3560 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3561 g1_policy()->record_satb_drain_time(finish_mark_ms);
3562 }
3563 // Record the number of elements currently on the mark stack, so we
3564 // only iterate over these. (Since evacuation may add to the mark
3565 // stack, doing more exposes race conditions.) If no mark is in
3566 // progress, this will be zero.
3567 _cm->set_oops_do_bound();
3568
3569 if (mark_in_progress()) {
3570 concurrent_mark()->newCSet();
3571 }
3572
3573 #if YOUNG_LIST_VERBOSE
3574 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3575 _young_list->print();
3576 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3577 #endif // YOUNG_LIST_VERBOSE
3578
3579 g1_policy()->choose_collection_set(target_pause_time_ms);
3580
3581 if (_hr_printer.is_active()) {
3582 HeapRegion* hr = g1_policy()->collection_set();
3583 while (hr != NULL) {
3584 G1HRPrinter::RegionType type;
3585 if (!hr->is_young()) {
3586 type = G1HRPrinter::Old;
3587 } else if (hr->is_survivor()) {
3588 type = G1HRPrinter::Survivor;
3589 } else {
3590 type = G1HRPrinter::Eden;
3591 }
3592 _hr_printer.cset(hr);
3593 hr = hr->next_in_collection_set();
3594 }
3595 }
3596
3597 // We have chosen the complete collection set. If marking is
3598 // active then, we clear the region fields of any of the
3599 // concurrent marking tasks whose region fields point into
3600 // the collection set as these values will become stale. This
3601 // will cause the owning marking threads to claim a new region
3602 // when marking restarts.
3603 if (mark_in_progress()) {
3604 concurrent_mark()->reset_active_task_region_fields_in_cset();
3605 }
3606
3607 #ifdef ASSERT
3608 VerifyCSetClosure cl;
3609 collection_set_iterate(&cl);
3610 #endif // ASSERT
3611
3612 setup_surviving_young_words();
3613
3614 // Set up the gc allocation regions.
3615 get_gc_alloc_regions();
3616
3617 // Actually do the work...
3618 evacuate_collection_set();
3619
3620 free_collection_set(g1_policy()->collection_set());
3621 g1_policy()->clear_collection_set();
3622
3623 cleanup_surviving_young_words();
3624
3625 // Start a new incremental collection set for the next pause.
3626 g1_policy()->start_incremental_cset_building();
3627
3628 // Clear the _cset_fast_test bitmap in anticipation of adding
3629 // regions to the incremental collection set for the next
3630 // evacuation pause.
3631 clear_cset_fast_test();
3632
3633 if (g1_policy()->in_young_gc_mode()) {
3634 _young_list->reset_sampled_info();
3635
3636 // Don't check the whole heap at this point as the
3637 // GC alloc regions from this pause have been tagged
3638 // as survivors and moved on to the survivor list.
3639 // Survivor regions will fail the !is_young() check.
3640 assert(check_young_list_empty(false /* check_heap */),
3641 "young list should be empty");
3642
3643 #if YOUNG_LIST_VERBOSE
3644 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3645 _young_list->print();
3646 #endif // YOUNG_LIST_VERBOSE
3647
3648 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3649 _young_list->first_survivor_region(),
3650 _young_list->last_survivor_region());
3651
3652 _young_list->reset_auxilary_lists();
3653 }
3654
3655 if (evacuation_failed()) {
3656 _summary_bytes_used = recalculate_used();
3657 } else {
3658 // The "used" of the the collection set have already been subtracted
3659 // when they were freed. Add in the bytes evacuated.
3660 _summary_bytes_used += g1_policy()->bytes_in_to_space();
3661 }
3662
3663 if (g1_policy()->in_young_gc_mode() &&
3664 g1_policy()->during_initial_mark_pause()) {
3665 concurrent_mark()->checkpointRootsInitialPost();
3666 set_marking_started();
3667 // CAUTION: after the doConcurrentMark() call below,
3668 // the concurrent marking thread(s) could be running
3669 // concurrently with us. Make sure that anything after
3670 // this point does not assume that we are the only GC thread
3671 // running. Note: of course, the actual marking work will
3672 // not start until the safepoint itself is released in
3673 // ConcurrentGCThread::safepoint_desynchronize().
3674 doConcurrentMark();
3675 }
3676
3677 allocate_dummy_regions();
3678
3679 #if YOUNG_LIST_VERBOSE
3680 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3681 _young_list->print();
3682 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3683 #endif // YOUNG_LIST_VERBOSE
3684
3685 init_mutator_alloc_region();
3686
3687 double end_time_sec = os::elapsedTime();
3688 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3689 g1_policy()->record_pause_time_ms(pause_time_ms);
3690 g1_policy()->record_collection_pause_end();
3691
3692 MemoryService::track_memory_usage();
3693
3694 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3695 HandleMark hm; // Discard invalid handles created during verification
3696 gclog_or_tty->print(" VerifyAfterGC:");
3697 prepare_for_verify();
3698 Universe::verify(/* allow dirty */ true,
3699 /* silent */ false,
3700 /* option */ VerifyOption_G1UsePrevMarking);
3701 }
3702
3703 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3704 ref_processor_stw()->verify_no_references_recorded();
3705
3706 // CM reference discovery will be re-enabled if necessary.
3707 }
3708
3709 {
3710 size_t expand_bytes = g1_policy()->expansion_amount();
3711 if (expand_bytes > 0) {
3712 size_t bytes_before = capacity();
3713 if (!expand(expand_bytes)) {
3714 // We failed to expand the heap so let's verify that
3715 // committed/uncommitted amount match the backing store
3716 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3717 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3718 }
3719 }
3720 }
3721
3722 // We should do this after we potentially expand the heap so
3723 // that all the COMMIT events are generated before the end GC
3724 // event, and after we retire the GC alloc regions so that all
3725 // RETIRE events are generated before the end GC event.
3726 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3727
3728 // We have to do this after we decide whether to expand the heap or not.
3729 g1_policy()->print_heap_transition();
3730
3731 if (mark_in_progress()) {
3732 concurrent_mark()->update_g1_committed();
3733 }
3734
3735 #ifdef TRACESPINNING
3736 ParallelTaskTerminator::print_termination_counts();
3737 #endif
3738
3739 gc_epilogue(false);
3740 }
3741
3742 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3743 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3744 print_tracing_info();
3745 vm_exit(-1);
3746 }
3747 }
3748
3749 _hrs.verify_optional();
3750 verify_region_sets_optional();
3751
3752 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3753 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3754
3755 if (PrintHeapAtGC) {
3756 Universe::print_heap_after_gc();
3757 }
3758 g1mm()->update_counters();
3759
3760 if (G1SummarizeRSetStats &&
3761 (G1SummarizeRSetStatsPeriod > 0) &&
3762 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3763 g1_rem_set()->print_summary_info();
3764 }
3765
3766 return true;
3767 }
3768
3769 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3770 {
3771 size_t gclab_word_size;
3772 switch (purpose) {
3773 case GCAllocForSurvived:
3774 gclab_word_size = YoungPLABSize;
3775 break;
3776 case GCAllocForTenured:
3777 gclab_word_size = OldPLABSize;
3778 break;
3779 default:
3780 assert(false, "unknown GCAllocPurpose");
3781 gclab_word_size = OldPLABSize;
3782 break;
3783 }
3784 return gclab_word_size;
3785 }
3786
3787 void G1CollectedHeap::init_mutator_alloc_region() {
3788 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3789 _mutator_alloc_region.init();
3790 }
3791
3792 void G1CollectedHeap::release_mutator_alloc_region() {
3793 _mutator_alloc_region.release();
3794 assert(_mutator_alloc_region.get() == NULL, "post-condition");
3795 }
3796
3797 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
3798 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
3799 // make sure we don't call set_gc_alloc_region() multiple times on
3800 // the same region
3801 assert(r == NULL || !r->is_gc_alloc_region(),
3802 "shouldn't already be a GC alloc region");
3803 assert(r == NULL || !r->isHumongous(),
3804 "humongous regions shouldn't be used as GC alloc regions");
3805
3806 HeapWord* original_top = NULL;
3807 if (r != NULL)
3808 original_top = r->top();
3809
3810 // We will want to record the used space in r as being there before gc.
3811 // One we install it as a GC alloc region it's eligible for allocation.
3812 // So record it now and use it later.
3813 size_t r_used = 0;
3814 if (r != NULL) {
3815 r_used = r->used();
3816
3817 if (G1CollectedHeap::use_parallel_gc_threads()) {
3818 // need to take the lock to guard against two threads calling
3819 // get_gc_alloc_region concurrently (very unlikely but...)
3820 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3821 r->save_marks();
3822 }
3823 }
3824 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
3825 _gc_alloc_regions[purpose] = r;
3826 if (old_alloc_region != NULL) {
3827 // Replace aliases too.
3828 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3829 if (_gc_alloc_regions[ap] == old_alloc_region) {
3830 _gc_alloc_regions[ap] = r;
3831 }
3832 }
3833 }
3834 if (r != NULL) {
3835 push_gc_alloc_region(r);
3836 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
3837 // We are using a region as a GC alloc region after it has been used
3838 // as a mutator allocation region during the current marking cycle.
3839 // The mutator-allocated objects are currently implicitly marked, but
3840 // when we move hr->next_top_at_mark_start() forward at the the end
3841 // of the GC pause, they won't be. We therefore mark all objects in
3842 // the "gap". We do this object-by-object, since marking densely
3843 // does not currently work right with marking bitmap iteration. This
3844 // means we rely on TLAB filling at the start of pauses, and no
3845 // "resuscitation" of filled TLAB's. If we want to do this, we need
3846 // to fix the marking bitmap iteration.
3847 HeapWord* curhw = r->next_top_at_mark_start();
3848 HeapWord* t = original_top;
3849
3850 while (curhw < t) {
3851 oop cur = (oop)curhw;
3852 // We'll assume parallel for generality. This is rare code.
3853 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
3854 curhw = curhw + cur->size();
3855 }
3856 assert(curhw == t, "Should have parsed correctly.");
3857 }
3858 if (G1PolicyVerbose > 1) {
3859 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
3860 "for survivors:", r->bottom(), original_top, r->end());
3861 r->print();
3862 }
3863 g1_policy()->record_before_bytes(r_used);
3864 }
3865 }
3866
3867 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
3868 assert(Thread::current()->is_VM_thread() ||
3869 FreeList_lock->owned_by_self(), "Precondition");
3870 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
3871 "Precondition.");
3872 hr->set_is_gc_alloc_region(true);
3873 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
3874 _gc_alloc_region_list = hr;
3875 }
3876
3877 #ifdef G1_DEBUG
3878 class FindGCAllocRegion: public HeapRegionClosure {
3879 public:
3880 bool doHeapRegion(HeapRegion* r) {
3881 if (r->is_gc_alloc_region()) {
3882 gclog_or_tty->print_cr("Region "HR_FORMAT" is still a GC alloc region",
3883 HR_FORMAT_PARAMS(r));
3884 }
3885 return false;
3886 }
3887 };
3888 #endif // G1_DEBUG
3889
3890 void G1CollectedHeap::forget_alloc_region_list() {
3891 assert_at_safepoint(true /* should_be_vm_thread */);
3892 while (_gc_alloc_region_list != NULL) {
3893 HeapRegion* r = _gc_alloc_region_list;
3894 assert(r->is_gc_alloc_region(), "Invariant.");
3895 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
3896 // newly allocated data in order to be able to apply deferred updates
3897 // before the GC is done for verification purposes (i.e to allow
3898 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
3899 // collection.
3900 r->ContiguousSpace::set_saved_mark();
3901 _gc_alloc_region_list = r->next_gc_alloc_region();
3902 r->set_next_gc_alloc_region(NULL);
3903 r->set_is_gc_alloc_region(false);
3904 if (r->is_survivor()) {
3905 if (r->is_empty()) {
3906 r->set_not_young();
3907 } else {
3908 _young_list->add_survivor_region(r);
3909 }
3910 }
3911 }
3912 #ifdef G1_DEBUG
3913 FindGCAllocRegion fa;
3914 heap_region_iterate(&fa);
3915 #endif // G1_DEBUG
3916 }
3917
3918
3919 bool G1CollectedHeap::check_gc_alloc_regions() {
3920 // TODO: allocation regions check
3921 return true;
3922 }
3923
3924 void G1CollectedHeap::get_gc_alloc_regions() {
3925 // First, let's check that the GC alloc region list is empty (it should)
3926 assert(_gc_alloc_region_list == NULL, "invariant");
3927
3928 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3929 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3930 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3931
3932 // Create new GC alloc regions.
3933 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3934 _retained_gc_alloc_regions[ap] = NULL;
3935
3936 if (alloc_region != NULL) {
3937 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3938
3939 // let's make sure that the GC alloc region is not tagged as such
3940 // outside a GC operation
3941 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3942
3943 if (alloc_region->in_collection_set() ||
3944 alloc_region->top() == alloc_region->end() ||
3945 alloc_region->top() == alloc_region->bottom() ||
3946 alloc_region->isHumongous()) {
3947 // we will discard the current GC alloc region if
3948 // * it's in the collection set (it can happen!),
3949 // * it's already full (no point in using it),
3950 // * it's empty (this means that it was emptied during
3951 // a cleanup and it should be on the free list now), or
3952 // * it's humongous (this means that it was emptied
3953 // during a cleanup and was added to the free list, but
3954 // has been subseqently used to allocate a humongous
3955 // object that may be less than the region size).
3956
3957 alloc_region = NULL;
3958 }
3959 }
3960
3961 if (alloc_region == NULL) {
3962 // we will get a new GC alloc region
3963 alloc_region = new_gc_alloc_region(ap, HeapRegion::GrainWords);
3964 } else {
3965 // the region was retained from the last collection
3966 ++_gc_alloc_region_counts[ap];
3967
3968 _hr_printer.reuse(alloc_region);
3969 }
3970
3971 if (alloc_region != NULL) {
3972 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3973 set_gc_alloc_region(ap, alloc_region);
3974 }
3975
3976 assert(_gc_alloc_regions[ap] == NULL ||
3977 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3978 "the GC alloc region should be tagged as such");
3979 assert(_gc_alloc_regions[ap] == NULL ||
3980 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3981 "the GC alloc region should be the same as the GC alloc list head");
3982 }
3983 // Set alternative regions for allocation purposes that have reached
3984 // their limit.
3985 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3986 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3987 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3988 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3989 }
3990 }
3991 assert(check_gc_alloc_regions(), "alloc regions messed up");
3992 }
3993
3994 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3995 // We keep a separate list of all regions that have been alloc regions in
3996 // the current collection pause. Forget that now. This method will
3997 // untag the GC alloc regions and tear down the GC alloc region
3998 // list. It's desirable that no regions are tagged as GC alloc
3999 // outside GCs.
4000
4001 forget_alloc_region_list();
4002
4003 // The current alloc regions contain objs that have survived
4004 // collection. Make them no longer GC alloc regions.
4005 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
4006 HeapRegion* r = _gc_alloc_regions[ap];
4007 _retained_gc_alloc_regions[ap] = NULL;
4008 _gc_alloc_region_counts[ap] = 0;
4009
4010 if (r != NULL) {
4011 // we retain nothing on _gc_alloc_regions between GCs
4012 set_gc_alloc_region(ap, NULL);
4013
4014 if (r->is_empty()) {
4015 // We didn't actually allocate anything in it; let's just put
4016 // it back on the free list.
4017 _free_list.add_as_head(r);
4018 } else if (_retain_gc_alloc_region[ap] && !totally) {
4019 // retain it so that we can use it at the beginning of the next GC
4020 _retained_gc_alloc_regions[ap] = r;
4021 }
4022 }
4023 }
4024 }
4025
4026 #ifndef PRODUCT
4027 // Useful for debugging
4028
4029 void G1CollectedHeap::print_gc_alloc_regions() {
4030 gclog_or_tty->print_cr("GC alloc regions");
4031 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
4032 HeapRegion* r = _gc_alloc_regions[ap];
4033 if (r == NULL) {
4034 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
4035 } else {
4036 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
4037 ap, r->bottom(), r->used());
4038 }
4039 }
4040 }
4041 #endif // PRODUCT
4042
4043 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4044 _drain_in_progress = false;
4045 set_evac_failure_closure(cl);
4046 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4047 }
4048
4049 void G1CollectedHeap::finalize_for_evac_failure() {
4050 assert(_evac_failure_scan_stack != NULL &&
4051 _evac_failure_scan_stack->length() == 0,
4052 "Postcondition");
4053 assert(!_drain_in_progress, "Postcondition");
4054 delete _evac_failure_scan_stack;
4055 _evac_failure_scan_stack = NULL;
4056 }
4057
4058 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
4059 private:
4060 G1CollectedHeap* _g1;
4061 DirtyCardQueue *_dcq;
4062 CardTableModRefBS* _ct_bs;
4063
4064 public:
4065 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
4066 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
4067
4068 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4069 virtual void do_oop( oop* p) { do_oop_work(p); }
4070 template <class T> void do_oop_work(T* p) {
4071 assert(_from->is_in_reserved(p), "paranoia");
4072 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
4073 !_from->is_survivor()) {
4074 size_t card_index = _ct_bs->index_for(p);
4075 if (_ct_bs->mark_card_deferred(card_index)) {
4076 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
4077 }
4078 }
4079 }
4080 };
4081
4082 class RemoveSelfPointerClosure: public ObjectClosure {
4083 private:
4084 G1CollectedHeap* _g1;
4085 ConcurrentMark* _cm;
4086 HeapRegion* _hr;
4087 size_t _prev_marked_bytes;
4088 size_t _next_marked_bytes;
4089 OopsInHeapRegionClosure *_cl;
4090 public:
4091 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
4092 OopsInHeapRegionClosure* cl) :
4093 _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
4094 _next_marked_bytes(0), _cl(cl) {}
4095
4096 size_t prev_marked_bytes() { return _prev_marked_bytes; }
4097 size_t next_marked_bytes() { return _next_marked_bytes; }
4098
4099 // <original comment>
4100 // The original idea here was to coalesce evacuated and dead objects.
4101 // However that caused complications with the block offset table (BOT).
4102 // In particular if there were two TLABs, one of them partially refined.
4103 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
4104 // The BOT entries of the unrefined part of TLAB_2 point to the start
4105 // of TLAB_2. If the last object of the TLAB_1 and the first object
4106 // of TLAB_2 are coalesced, then the cards of the unrefined part
4107 // would point into middle of the filler object.
4108 // The current approach is to not coalesce and leave the BOT contents intact.
4109 // </original comment>
4110 //
4111 // We now reset the BOT when we start the object iteration over the
4112 // region and refine its entries for every object we come across. So
4113 // the above comment is not really relevant and we should be able
4114 // to coalesce dead objects if we want to.
4115 void do_object(oop obj) {
4116 HeapWord* obj_addr = (HeapWord*) obj;
4117 assert(_hr->is_in(obj_addr), "sanity");
4118 size_t obj_size = obj->size();
4119 _hr->update_bot_for_object(obj_addr, obj_size);
4120 if (obj->is_forwarded() && obj->forwardee() == obj) {
4121 // The object failed to move.
4122 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
4123 _cm->markPrev(obj);
4124 assert(_cm->isPrevMarked(obj), "Should be marked!");
4125 _prev_marked_bytes += (obj_size * HeapWordSize);
4126 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
4127 _cm->markAndGrayObjectIfNecessary(obj);
4128 }
4129 obj->set_mark(markOopDesc::prototype());
4130 // While we were processing RSet buffers during the
4131 // collection, we actually didn't scan any cards on the
4132 // collection set, since we didn't want to update remebered
4133 // sets with entries that point into the collection set, given
4134 // that live objects fromthe collection set are about to move
4135 // and such entries will be stale very soon. This change also
4136 // dealt with a reliability issue which involved scanning a
4137 // card in the collection set and coming across an array that
4138 // was being chunked and looking malformed. The problem is
4139 // that, if evacuation fails, we might have remembered set
4140 // entries missing given that we skipped cards on the
4141 // collection set. So, we'll recreate such entries now.
4142 obj->oop_iterate(_cl);
4143 assert(_cm->isPrevMarked(obj), "Should be marked!");
4144 } else {
4145 // The object has been either evacuated or is dead. Fill it with a
4146 // dummy object.
4147 MemRegion mr((HeapWord*)obj, obj_size);
4148 CollectedHeap::fill_with_object(mr);
4149 _cm->clearRangeBothMaps(mr);
4150 }
4151 }
4152 };
4153
4154 void G1CollectedHeap::remove_self_forwarding_pointers() {
4155 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
4156 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
4157 UpdateRSetDeferred deferred_update(_g1h, &dcq);
4158 OopsInHeapRegionClosure *cl;
4159 if (G1DeferredRSUpdate) {
4160 cl = &deferred_update;
4161 } else {
4162 cl = &immediate_update;
4163 }
4164 HeapRegion* cur = g1_policy()->collection_set();
4165 while (cur != NULL) {
4166 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4167 assert(!cur->isHumongous(), "sanity");
4168
4169 if (cur->evacuation_failed()) {
4170 assert(cur->in_collection_set(), "bad CS");
4171 RemoveSelfPointerClosure rspc(_g1h, cur, cl);
4172
4173 // In the common case we make sure that this is done when the
4174 // region is freed so that it is "ready-to-go" when it's
4175 // re-allocated. However, when evacuation failure happens, a
4176 // region will remain in the heap and might ultimately be added
4177 // to a CSet in the future. So we have to be careful here and
4178 // make sure the region's RSet is ready for parallel iteration
4179 // whenever this might be required in the future.
4180 cur->rem_set()->reset_for_par_iteration();
4181 cur->reset_bot();
4182 cl->set_region(cur);
4183 cur->object_iterate(&rspc);
4184
4185 // A number of manipulations to make the TAMS be the current top,
4186 // and the marked bytes be the ones observed in the iteration.
4187 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
4188 // The comments below are the postconditions achieved by the
4189 // calls. Note especially the last such condition, which says that
4190 // the count of marked bytes has been properly restored.
4191 cur->note_start_of_marking(false);
4192 // _next_top_at_mark_start == top, _next_marked_bytes == 0
4193 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
4194 // _next_marked_bytes == prev_marked_bytes.
4195 cur->note_end_of_marking();
4196 // _prev_top_at_mark_start == top(),
4197 // _prev_marked_bytes == prev_marked_bytes
4198 }
4199 // If there is no mark in progress, we modified the _next variables
4200 // above needlessly, but harmlessly.
4201 if (_g1h->mark_in_progress()) {
4202 cur->note_start_of_marking(false);
4203 // _next_top_at_mark_start == top, _next_marked_bytes == 0
4204 // _next_marked_bytes == next_marked_bytes.
4205 }
4206
4207 // Now make sure the region has the right index in the sorted array.
4208 g1_policy()->note_change_in_marked_bytes(cur);
4209 }
4210 cur = cur->next_in_collection_set();
4211 }
4212 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
4213
4214 // Now restore saved marks, if any.
4215 if (_objs_with_preserved_marks != NULL) {
4216 assert(_preserved_marks_of_objs != NULL, "Both or none.");
4217 guarantee(_objs_with_preserved_marks->length() ==
4218 _preserved_marks_of_objs->length(), "Both or none.");
4219 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
4220 oop obj = _objs_with_preserved_marks->at(i);
4221 markOop m = _preserved_marks_of_objs->at(i);
4222 obj->set_mark(m);
4223 }
4224 // Delete the preserved marks growable arrays (allocated on the C heap).
4225 delete _objs_with_preserved_marks;
4226 delete _preserved_marks_of_objs;
4227 _objs_with_preserved_marks = NULL;
4228 _preserved_marks_of_objs = NULL;
4229 }
4230 }
4231
4232 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4233 _evac_failure_scan_stack->push(obj);
4234 }
4235
4236 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4237 assert(_evac_failure_scan_stack != NULL, "precondition");
4238
4239 while (_evac_failure_scan_stack->length() > 0) {
4240 oop obj = _evac_failure_scan_stack->pop();
4241 _evac_failure_closure->set_region(heap_region_containing(obj));
4242 obj->oop_iterate_backwards(_evac_failure_closure);
4243 }
4244 }
4245
4246 oop
4247 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4248 oop old) {
4249 assert(obj_in_cs(old),
4250 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4251 (HeapWord*) old));
4252 markOop m = old->mark();
4253 oop forward_ptr = old->forward_to_atomic(old);
4254 if (forward_ptr == NULL) {
4255 // Forward-to-self succeeded.
4256 if (_evac_failure_closure != cl) {
4257 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4258 assert(!_drain_in_progress,
4259 "Should only be true while someone holds the lock.");
4260 // Set the global evac-failure closure to the current thread's.
4261 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4262 set_evac_failure_closure(cl);
4263 // Now do the common part.
4264 handle_evacuation_failure_common(old, m);
4265 // Reset to NULL.
4266 set_evac_failure_closure(NULL);
4267 } else {
4268 // The lock is already held, and this is recursive.
4269 assert(_drain_in_progress, "This should only be the recursive case.");
4270 handle_evacuation_failure_common(old, m);
4271 }
4272 return old;
4273 } else {
4274 // Forward-to-self failed. Either someone else managed to allocate
4275 // space for this object (old != forward_ptr) or they beat us in
4276 // self-forwarding it (old == forward_ptr).
4277 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4278 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4279 "should not be in the CSet",
4280 (HeapWord*) old, (HeapWord*) forward_ptr));
4281 return forward_ptr;
4282 }
4283 }
4284
4285 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4286 set_evacuation_failed(true);
4287
4288 preserve_mark_if_necessary(old, m);
4289
4290 HeapRegion* r = heap_region_containing(old);
4291 if (!r->evacuation_failed()) {
4292 r->set_evacuation_failed(true);
4293 _hr_printer.evac_failure(r);
4294 }
4295
4296 push_on_evac_failure_scan_stack(old);
4297
4298 if (!_drain_in_progress) {
4299 // prevent recursion in copy_to_survivor_space()
4300 _drain_in_progress = true;
4301 drain_evac_failure_scan_stack();
4302 _drain_in_progress = false;
4303 }
4304 }
4305
4306 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4307 assert(evacuation_failed(), "Oversaving!");
4308 // We want to call the "for_promotion_failure" version only in the
4309 // case of a promotion failure.
4310 if (m->must_be_preserved_for_promotion_failure(obj)) {
4311 if (_objs_with_preserved_marks == NULL) {
4312 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4313 _objs_with_preserved_marks =
4314 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4315 _preserved_marks_of_objs =
4316 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4317 }
4318 _objs_with_preserved_marks->push(obj);
4319 _preserved_marks_of_objs->push(m);
4320 }
4321 }
4322
4323 // *** Parallel G1 Evacuation
4324
4325 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4326 size_t word_size) {
4327 assert(!isHumongous(word_size),
4328 err_msg("we should not be seeing humongous allocation requests "
4329 "during GC, word_size = "SIZE_FORMAT, word_size));
4330
4331 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
4332 // let the caller handle alloc failure
4333 if (alloc_region == NULL) return NULL;
4334
4335 HeapWord* block = alloc_region->par_allocate(word_size);
4336 if (block == NULL) {
4337 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
4338 }
4339 return block;
4340 }
4341
4342 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
4343 bool par) {
4344 // Another thread might have obtained alloc_region for the given
4345 // purpose, and might be attempting to allocate in it, and might
4346 // succeed. Therefore, we can't do the "finalization" stuff on the
4347 // region below until we're sure the last allocation has happened.
4348 // We ensure this by allocating the remaining space with a garbage
4349 // object.
4350 if (par) par_allocate_remaining_space(alloc_region);
4351 // Now we can do the post-GC stuff on the region.
4352 alloc_region->note_end_of_copying();
4353 g1_policy()->record_after_bytes(alloc_region->used());
4354 _hr_printer.retire(alloc_region);
4355 }
4356
4357 HeapWord*
4358 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
4359 HeapRegion* alloc_region,
4360 bool par,
4361 size_t word_size) {
4362 assert(!isHumongous(word_size),
4363 err_msg("we should not be seeing humongous allocation requests "
4364 "during GC, word_size = "SIZE_FORMAT, word_size));
4365
4366 // We need to make sure we serialize calls to this method. Given
4367 // that the FreeList_lock guards accesses to the free_list anyway,
4368 // and we need to potentially remove a region from it, we'll use it
4369 // to protect the whole call.
4370 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4371
4372 HeapWord* block = NULL;
4373 // In the parallel case, a previous thread to obtain the lock may have
4374 // already assigned a new gc_alloc_region.
4375 if (alloc_region != _gc_alloc_regions[purpose]) {
4376 assert(par, "But should only happen in parallel case.");
4377 alloc_region = _gc_alloc_regions[purpose];
4378 if (alloc_region == NULL) return NULL;
4379 block = alloc_region->par_allocate(word_size);
4380 if (block != NULL) return block;
4381 // Otherwise, continue; this new region is empty, too.
4382 }
4383 assert(alloc_region != NULL, "We better have an allocation region");
4384 retire_alloc_region(alloc_region, par);
4385
4386 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
4387 // Cannot allocate more regions for the given purpose.
4388 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
4389 // Is there an alternative?
4390 if (purpose != alt_purpose) {
4391 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
4392 // Has not the alternative region been aliased?
4393 if (alloc_region != alt_region && alt_region != NULL) {
4394 // Try to allocate in the alternative region.
4395 if (par) {
4396 block = alt_region->par_allocate(word_size);
4397 } else {
4398 block = alt_region->allocate(word_size);
4399 }
4400 // Make an alias.
4401 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
4402 if (block != NULL) {
4403 return block;
4404 }
4405 retire_alloc_region(alt_region, par);
4406 }
4407 // Both the allocation region and the alternative one are full
4408 // and aliased, replace them with a new allocation region.
4409 purpose = alt_purpose;
4410 } else {
4411 set_gc_alloc_region(purpose, NULL);
4412 return NULL;
4413 }
4414 }
4415
4416 // Now allocate a new region for allocation.
4417 alloc_region = new_gc_alloc_region(purpose, word_size);
4418
4419 // let the caller handle alloc failure
4420 if (alloc_region != NULL) {
4421
4422 assert(check_gc_alloc_regions(), "alloc regions messed up");
4423 assert(alloc_region->saved_mark_at_top(),
4424 "Mark should have been saved already.");
4425 // This must be done last: once it's installed, other regions may
4426 // allocate in it (without holding the lock.)
4427 set_gc_alloc_region(purpose, alloc_region);
4428
4429 if (par) {
4430 block = alloc_region->par_allocate(word_size);
4431 } else {
4432 block = alloc_region->allocate(word_size);
4433 }
4434 // Caller handles alloc failure.
4435 } else {
4436 // This sets other apis using the same old alloc region to NULL, also.
4437 set_gc_alloc_region(purpose, NULL);
4438 }
4439 return block; // May be NULL.
4440 }
4441
4442 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
4443 HeapWord* block = NULL;
4444 size_t free_words;
4445 do {
4446 free_words = r->free()/HeapWordSize;
4447 // If there's too little space, no one can allocate, so we're done.
4448 if (free_words < CollectedHeap::min_fill_size()) return;
4449 // Otherwise, try to claim it.
4450 block = r->par_allocate(free_words);
4451 } while (block == NULL);
4452 fill_with_object(block, free_words);
4453 }
4454
4455 #ifndef PRODUCT
4456 bool GCLabBitMapClosure::do_bit(size_t offset) {
4457 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4458 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4459 return true;
4460 }
4461 #endif // PRODUCT
4462
4463 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4464 : _g1h(g1h),
4465 _refs(g1h->task_queue(queue_num)),
4466 _dcq(&g1h->dirty_card_queue_set()),
4467 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4468 _g1_rem(g1h->g1_rem_set()),
4469 _hash_seed(17), _queue_num(queue_num),
4470 _term_attempts(0),
4471 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4472 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4473 _age_table(false),
4474 _strong_roots_time(0), _term_time(0),
4475 _alloc_buffer_waste(0), _undo_waste(0)
4476 {
4477 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4478 // we "sacrifice" entry 0 to keep track of surviving bytes for
4479 // non-young regions (where the age is -1)
4480 // We also add a few elements at the beginning and at the end in
4481 // an attempt to eliminate cache contention
4482 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
4483 size_t array_length = PADDING_ELEM_NUM +
4484 real_length +
4485 PADDING_ELEM_NUM;
4486 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4487 if (_surviving_young_words_base == NULL)
4488 vm_exit_out_of_memory(array_length * sizeof(size_t),
4489 "Not enough space for young surv histo.");
4490 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4491 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4492
4493 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4494 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4495
4496 _start = os::elapsedTime();
4497 }
4498
4499 void
4500 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4501 {
4502 st->print_raw_cr("GC Termination Stats");
4503 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4504 " ------waste (KiB)------");
4505 st->print_raw_cr("thr ms ms % ms % attempts"
4506 " total alloc undo");
4507 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4508 " ------- ------- -------");
4509 }
4510
4511 void
4512 G1ParScanThreadState::print_termination_stats(int i,
4513 outputStream* const st) const
4514 {
4515 const double elapsed_ms = elapsed_time() * 1000.0;
4516 const double s_roots_ms = strong_roots_time() * 1000.0;
4517 const double term_ms = term_time() * 1000.0;
4518 st->print_cr("%3d %9.2f %9.2f %6.2f "
4519 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4520 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4521 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4522 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4523 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4524 alloc_buffer_waste() * HeapWordSize / K,
4525 undo_waste() * HeapWordSize / K);
4526 }
4527
4528 #ifdef ASSERT
4529 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4530 assert(ref != NULL, "invariant");
4531 assert(UseCompressedOops, "sanity");
4532 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4533 oop p = oopDesc::load_decode_heap_oop(ref);
4534 assert(_g1h->is_in_g1_reserved(p),
4535 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4536 return true;
4537 }
4538
4539 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4540 assert(ref != NULL, "invariant");
4541 if (has_partial_array_mask(ref)) {
4542 // Must be in the collection set--it's already been copied.
4543 oop p = clear_partial_array_mask(ref);
4544 assert(_g1h->obj_in_cs(p),
4545 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4546 } else {
4547 oop p = oopDesc::load_decode_heap_oop(ref);
4548 assert(_g1h->is_in_g1_reserved(p),
4549 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4550 }
4551 return true;
4552 }
4553
4554 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4555 if (ref.is_narrow()) {
4556 return verify_ref((narrowOop*) ref);
4557 } else {
4558 return verify_ref((oop*) ref);
4559 }
4560 }
4561 #endif // ASSERT
4562
4563 void G1ParScanThreadState::trim_queue() {
4564 assert(_evac_cl != NULL, "not set");
4565 assert(_evac_failure_cl != NULL, "not set");
4566 assert(_partial_scan_cl != NULL, "not set");
4567
4568 StarTask ref;
4569 do {
4570 // Drain the overflow stack first, so other threads can steal.
4571 while (refs()->pop_overflow(ref)) {
4572 deal_with_reference(ref);
4573 }
4574
4575 while (refs()->pop_local(ref)) {
4576 deal_with_reference(ref);
4577 }
4578 } while (!refs()->is_empty());
4579 }
4580
4581 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4582 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4583 _par_scan_state(par_scan_state) { }
4584
4585 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
4586 // This is called _after_ do_oop_work has been called, hence after
4587 // the object has been relocated to its new location and *p points
4588 // to its new location.
4589
4590 T heap_oop = oopDesc::load_heap_oop(p);
4591 if (!oopDesc::is_null(heap_oop)) {
4592 oop obj = oopDesc::decode_heap_oop(heap_oop);
4593 HeapWord* addr = (HeapWord*)obj;
4594 if (_g1->is_in_g1_reserved(addr)) {
4595 _cm->grayRoot(oop(addr));
4596 }
4597 }
4598 }
4599
4600 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4601 size_t word_sz = old->size();
4602 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4603 // +1 to make the -1 indexes valid...
4604 int young_index = from_region->young_index_in_cset()+1;
4605 assert( (from_region->is_young() && young_index > 0) ||
4606 (!from_region->is_young() && young_index == 0), "invariant" );
4607 G1CollectorPolicy* g1p = _g1->g1_policy();
4608 markOop m = old->mark();
4609 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4610 : m->age();
4611 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4612 word_sz);
4613 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4614 oop obj = oop(obj_ptr);
4615
4616 if (obj_ptr == NULL) {
4617 // This will either forward-to-self, or detect that someone else has
4618 // installed a forwarding pointer.
4619 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4620 return _g1->handle_evacuation_failure_par(cl, old);
4621 }
4622
4623 // We're going to allocate linearly, so might as well prefetch ahead.
4624 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4625
4626 oop forward_ptr = old->forward_to_atomic(obj);
4627 if (forward_ptr == NULL) {
4628 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4629 if (g1p->track_object_age(alloc_purpose)) {
4630 // We could simply do obj->incr_age(). However, this causes a
4631 // performance issue. obj->incr_age() will first check whether
4632 // the object has a displaced mark by checking its mark word;
4633 // getting the mark word from the new location of the object
4634 // stalls. So, given that we already have the mark word and we
4635 // are about to install it anyway, it's better to increase the
4636 // age on the mark word, when the object does not have a
4637 // displaced mark word. We're not expecting many objects to have
4638 // a displaced marked word, so that case is not optimized
4639 // further (it could be...) and we simply call obj->incr_age().
4640
4641 if (m->has_displaced_mark_helper()) {
4642 // in this case, we have to install the mark word first,
4643 // otherwise obj looks to be forwarded (the old mark word,
4644 // which contains the forward pointer, was copied)
4645 obj->set_mark(m);
4646 obj->incr_age();
4647 } else {
4648 m = m->incr_age();
4649 obj->set_mark(m);
4650 }
4651 _par_scan_state->age_table()->add(obj, word_sz);
4652 } else {
4653 obj->set_mark(m);
4654 }
4655
4656 // preserve "next" mark bit
4657 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4658 if (!use_local_bitmaps ||
4659 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4660 // if we couldn't mark it on the local bitmap (this happens when
4661 // the object was not allocated in the GCLab), we have to bite
4662 // the bullet and do the standard parallel mark
4663 _cm->markAndGrayObjectIfNecessary(obj);
4664 }
4665 #if 1
4666 if (_g1->isMarkedNext(old)) {
4667 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4668 }
4669 #endif
4670 }
4671
4672 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4673 surv_young_words[young_index] += word_sz;
4674
4675 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4676 arrayOop(old)->set_length(0);
4677 oop* old_p = set_partial_array_mask(old);
4678 _par_scan_state->push_on_queue(old_p);
4679 } else {
4680 // No point in using the slower heap_region_containing() method,
4681 // given that we know obj is in the heap.
4682 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4683 obj->oop_iterate_backwards(_scanner);
4684 }
4685 } else {
4686 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4687 obj = forward_ptr;
4688 }
4689 return obj;
4690 }
4691
4692 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
4693 template <class T>
4694 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>::do_oop_work(T* p) {
4695 oop obj = oopDesc::load_decode_heap_oop(p);
4696 assert(barrier != G1BarrierRS || obj != NULL,
4697 "Precondition: G1BarrierRS implies obj is nonNull");
4698
4699 // here the null check is implicit in the cset_fast_test() test
4700 if (_g1->in_cset_fast_test(obj)) {
4701 if (obj->is_forwarded()) {
4702 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4703 } else {
4704 oop copy_oop = copy_to_survivor_space(obj);
4705 oopDesc::encode_store_heap_oop(p, copy_oop);
4706 }
4707 // When scanning the RS, we only care about objs in CS.
4708 if (barrier == G1BarrierRS) {
4709 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4710 }
4711 }
4712
4713 if (barrier == G1BarrierEvac && obj != NULL) {
4714 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4715 }
4716
4717 if (do_gen_barrier && obj != NULL) {
4718 par_do_barrier(p);
4719 }
4720 }
4721
4722 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4723 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4724
4725 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4726 assert(has_partial_array_mask(p), "invariant");
4727 oop old = clear_partial_array_mask(p);
4728 assert(old->is_objArray(), "must be obj array");
4729 assert(old->is_forwarded(), "must be forwarded");
4730 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4731
4732 objArrayOop obj = objArrayOop(old->forwardee());
4733 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4734 // Process ParGCArrayScanChunk elements now
4735 // and push the remainder back onto queue
4736 int start = arrayOop(old)->length();
4737 int end = obj->length();
4738 int remainder = end - start;
4739 assert(start <= end, "just checking");
4740 if (remainder > 2 * ParGCArrayScanChunk) {
4741 // Test above combines last partial chunk with a full chunk
4742 end = start + ParGCArrayScanChunk;
4743 arrayOop(old)->set_length(end);
4744 // Push remainder.
4745 oop* old_p = set_partial_array_mask(old);
4746 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4747 _par_scan_state->push_on_queue(old_p);
4748 } else {
4749 // Restore length so that the heap remains parsable in
4750 // case of evacuation failure.
4751 arrayOop(old)->set_length(end);
4752 }
4753 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4754 // process our set of indices (include header in first chunk)
4755 obj->oop_iterate_range(&_scanner, start, end);
4756 }
4757
4758 class G1ParEvacuateFollowersClosure : public VoidClosure {
4759 protected:
4760 G1CollectedHeap* _g1h;
4761 G1ParScanThreadState* _par_scan_state;
4762 RefToScanQueueSet* _queues;
4763 ParallelTaskTerminator* _terminator;
4764
4765 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4766 RefToScanQueueSet* queues() { return _queues; }
4767 ParallelTaskTerminator* terminator() { return _terminator; }
4768
4769 public:
4770 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4771 G1ParScanThreadState* par_scan_state,
4772 RefToScanQueueSet* queues,
4773 ParallelTaskTerminator* terminator)
4774 : _g1h(g1h), _par_scan_state(par_scan_state),
4775 _queues(queues), _terminator(terminator) {}
4776
4777 void do_void();
4778
4779 private:
4780 inline bool offer_termination();
4781 };
4782
4783 bool G1ParEvacuateFollowersClosure::offer_termination() {
4784 G1ParScanThreadState* const pss = par_scan_state();
4785 pss->start_term_time();
4786 const bool res = terminator()->offer_termination();
4787 pss->end_term_time();
4788 return res;
4789 }
4790
4791 void G1ParEvacuateFollowersClosure::do_void() {
4792 StarTask stolen_task;
4793 G1ParScanThreadState* const pss = par_scan_state();
4794 pss->trim_queue();
4795
4796 do {
4797 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4798 assert(pss->verify_task(stolen_task), "sanity");
4799 if (stolen_task.is_narrow()) {
4800 pss->deal_with_reference((narrowOop*) stolen_task);
4801 } else {
4802 pss->deal_with_reference((oop*) stolen_task);
4803 }
4804
4805 // We've just processed a reference and we might have made
4806 // available new entries on the queues. So we have to make sure
4807 // we drain the queues as necessary.
4808 pss->trim_queue();
4809 }
4810 } while (!offer_termination());
4811
4812 pss->retire_alloc_buffers();
4813 }
4814
4815 class G1ParTask : public AbstractGangTask {
4816 protected:
4817 G1CollectedHeap* _g1h;
4818 RefToScanQueueSet *_queues;
4819 ParallelTaskTerminator _terminator;
4820 int _n_workers;
4821
4822 Mutex _stats_lock;
4823 Mutex* stats_lock() { return &_stats_lock; }
4824
4825 size_t getNCards() {
4826 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4827 / G1BlockOffsetSharedArray::N_bytes;
4828 }
4829
4830 public:
4831 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4832 : AbstractGangTask("G1 collection"),
4833 _g1h(g1h),
4834 _queues(task_queues),
4835 _terminator(workers, _queues),
4836 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4837 _n_workers(workers)
4838 {}
4839
4840 RefToScanQueueSet* queues() { return _queues; }
4841
4842 RefToScanQueue *work_queue(int i) {
4843 return queues()->queue(i);
4844 }
4845
4846 void work(int i) {
4847 if (i >= _n_workers) return; // no work needed this round
4848
4849 double start_time_ms = os::elapsedTime() * 1000.0;
4850 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4851
4852 ResourceMark rm;
4853 HandleMark hm;
4854
4855 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4856
4857 G1ParScanThreadState pss(_g1h, i);
4858 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, rp);
4859 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4860 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, rp);
4861
4862 pss.set_evac_closure(&scan_evac_cl);
4863 pss.set_evac_failure_closure(&evac_failure_cl);
4864 pss.set_partial_scan_closure(&partial_scan_cl);
4865
4866 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4867 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss, rp);
4868
4869 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4870 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss, rp);
4871
4872 OopClosure* scan_root_cl = &only_scan_root_cl;
4873 OopsInHeapRegionClosure* scan_perm_cl = &only_scan_perm_cl;
4874
4875 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4876 // We also need to mark copied objects.
4877 scan_root_cl = &scan_mark_root_cl;
4878 scan_perm_cl = &scan_mark_perm_cl;
4879 }
4880
4881 // The following closure is used to scan RSets looking for reference
4882 // fields that point into the collection set. The actual field iteration
4883 // is performed by a FilterIntoCSClosure, whose do_oop method calls the
4884 // do_oop method of the following closure.
4885 // Therefore we want to record the reference processor in the
4886 // FilterIntoCSClosure. To do so we record the STW reference
4887 // processor into the following closure and pass it to the
4888 // FilterIntoCSClosure in HeapRegionDCTOC::walk_mem_region_with_cl.
4889 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss, rp);
4890
4891 pss.start_strong_roots();
4892 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4893 SharedHeap::SO_AllClasses,
4894 scan_root_cl,
4895 &push_heap_rs_cl,
4896 scan_perm_cl,
4897 i);
4898 pss.end_strong_roots();
4899
4900 {
4901 double start = os::elapsedTime();
4902 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4903 evac.do_void();
4904 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4905 double term_ms = pss.term_time()*1000.0;
4906 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4907 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4908 }
4909 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4910 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4911
4912 // Clean up any par-expanded rem sets.
4913 HeapRegionRemSet::par_cleanup();
4914
4915 if (ParallelGCVerbose) {
4916 MutexLocker x(stats_lock());
4917 pss.print_termination_stats(i);
4918 }
4919
4920 assert(pss.refs()->is_empty(), "should be empty");
4921 double end_time_ms = os::elapsedTime() * 1000.0;
4922 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4923 }
4924 };
4925
4926 // *** Common G1 Evacuation Stuff
4927
4928 // This method is run in a GC worker.
4929
4930 void
4931 G1CollectedHeap::
4932 g1_process_strong_roots(bool collecting_perm_gen,
4933 SharedHeap::ScanningOption so,
4934 OopClosure* scan_non_heap_roots,
4935 OopsInHeapRegionClosure* scan_rs,
4936 OopsInGenClosure* scan_perm,
4937 int worker_i) {
4938
4939 // First scan the strong roots, including the perm gen.
4940 double ext_roots_start = os::elapsedTime();
4941 double closure_app_time_sec = 0.0;
4942
4943 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4944 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4945 buf_scan_perm.set_generation(perm_gen());
4946
4947 // Walk the code cache w/o buffering, because StarTask cannot handle
4948 // unaligned oop locations.
4949 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4950
4951 process_strong_roots(false, // no scoping; this is parallel code
4952 collecting_perm_gen, so,
4953 &buf_scan_non_heap_roots,
4954 &eager_scan_code_roots,
4955 &buf_scan_perm);
4956
4957 // Now the CM ref_processor roots.
4958 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4959 // We need to treat the discovered reference lists of the
4960 // concurrent mark ref processor as roots and keep entries
4961 // (which are added by the marking threads) on them live
4962 // until they can be processed at the end of marking.
4963 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4964 ref_processor_cm()->oops_do(&buf_scan_non_heap_roots);
4965 }
4966
4967 // Finish up any enqueued closure apps (attributed as object copy time).
4968 buf_scan_non_heap_roots.done();
4969 buf_scan_perm.done();
4970
4971 double ext_roots_end = os::elapsedTime();
4972
4973 g1_policy()->reset_obj_copy_time(worker_i);
4974 double obj_copy_time_sec = buf_scan_perm.closure_app_seconds() +
4975 buf_scan_non_heap_roots.closure_app_seconds();
4976 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4977
4978 double ext_root_time_ms =
4979 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4980
4981 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4982
4983 // Scan strong roots in mark stack.
4984 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4985 concurrent_mark()->oops_do(scan_non_heap_roots);
4986 }
4987 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4988 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4989
4990 // Now scan the complement of the collection set.
4991 if (scan_rs != NULL) {
4992 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4993 }
4994
4995 _process_strong_tasks->all_tasks_completed();
4996 }
4997
4998 void
4999 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
5000 OopClosure* non_root_closure) {
5001 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5002 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
5003 }
5004
5005
5006 class SaveMarksClosure: public HeapRegionClosure {
5007 public:
5008 bool doHeapRegion(HeapRegion* r) {
5009 r->save_marks();
5010 return false;
5011 }
5012 };
5013
5014 void G1CollectedHeap::save_marks() {
5015 if (!CollectedHeap::use_parallel_gc_threads()) {
5016 SaveMarksClosure sm;
5017 heap_region_iterate(&sm);
5018 }
5019 // We do this even in the parallel case
5020 perm_gen()->save_marks();
5021 }
5022
5023 // Weak Reference Processing support
5024
5025 bool G1STWIsAliveClosure::do_object_b(oop p) {
5026 // An object is reachable if it is outside the collection set,
5027 // or is inside and copied.
5028 #ifdef G1_DEBUG
5029 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
5030 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
5031 !_g1->obj_in_cs(p) || p->is_forwarded());
5032 #endif // G1_DEBUG
5033 return !_g1->obj_in_cs(p) || p->is_forwarded();
5034 }
5035
5036 // Non Copying Keep Alive closure
5037 class G1KeepAliveClosure: public OopClosure {
5038 G1CollectedHeap* _g1;
5039 public:
5040 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5041 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5042 void do_oop( oop* p) {
5043 oop obj = *p;
5044 #ifdef G1_DEBUG
5045 gclog_or_tty->print_cr("Non-copy keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
5046 p, (void*) obj, (void*) *p);
5047 #endif // G1_DEBUG
5048
5049 if (_g1->obj_in_cs(obj)) {
5050 assert( obj->is_forwarded(), "invariant" );
5051 *p = obj->forwardee();
5052 #ifdef G1_DEBUG
5053 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
5054 (void*) obj, (void*) *p);
5055 #endif // G1_DEBUG
5056 }
5057 }
5058 };
5059
5060 // Copying Keep Alive closure - can be called from both
5061 // serial and parallel code as long as different worker
5062 // threads utilize different G1ParScanThreadState instances
5063 // and different queues.
5064
5065 class G1CopyingKeepAliveClosure: public OopClosure {
5066 G1CollectedHeap* _g1h;
5067 OopClosure* _copy_non_heap_obj_cl;
5068 OopsInHeapRegionClosure* _copy_perm_obj_cl;
5069 G1ParScanThreadState* _par_scan_state;
5070
5071 public:
5072 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5073 OopClosure* non_heap_obj_cl,
5074 OopsInHeapRegionClosure* perm_obj_cl,
5075 G1ParScanThreadState* pss):
5076 _g1h(g1h),
5077 _copy_non_heap_obj_cl(non_heap_obj_cl),
5078 _copy_perm_obj_cl(perm_obj_cl),
5079 _par_scan_state(pss)
5080 {}
5081
5082 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5083 virtual void do_oop( oop* p) { do_oop_work(p); }
5084
5085 template <class T> void do_oop_work(T* p) {
5086 oop obj = oopDesc::load_decode_heap_oop(p);
5087 #ifdef G1_DEBUG
5088 gclog_or_tty->print_cr("Copying keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
5089 p, (void*) obj, (void*) *p);
5090 #endif // G1_DEBUG
5091
5092 if (_g1h->obj_in_cs(obj)) {
5093 // If the referent object has been forwarded (either copied
5094 // to a new location or to itself in the event of an
5095 // evacuation failure) then we need to update the reference
5096 // field and, if both reference and referent are in the G1
5097 // heap, update the RSet for the referent.
5098 //
5099 // If the referent has not been forwarded then we have to keep
5100 // it alive by policy. Therefore we have copy the referent.
5101 // If the reference field is in the G1 heap then we can push
5102 // on the PSS queue. When the queue is drained (after each
5103 // phase of reference processing) the object and it's followers
5104 // will be copied. If the reference field is not in the G1 heap
5105 // then we need to use the the non-heap or perm closures to
5106 // copy the object to avoid updating the RSet.
5107 #ifdef G1_DEBUG
5108 if (obj->is_forwarded()) {
5109 gclog_or_tty->print_cr(" in CSet: forwarded "PTR_FORMAT" -> "PTR_FORMAT,
5110 (void*) obj, (void*) *p);
5111 }
5112 #endif // G1_DEBUG
5113
5114 if (_g1h->is_in_g1_reserved(p)) {
5115 #ifdef G1_DEBUG
5116 gclog_or_tty->print_cr(" in CSet: pushing "PTR_FORMAT, p);
5117 #endif // G1_DEBUG
5118 _par_scan_state->push_on_queue(p);
5119 } else {
5120 #ifdef G1_DEBUG
5121 gclog_or_tty->print_cr(" in CSet: applying closure to "PTR_FORMAT, p);
5122 #endif // G1_DEBUG
5123 // The reference field is not in the G1 heap.
5124 if (_g1h->perm_gen()->is_in(p)) {
5125 _copy_perm_obj_cl->do_oop(p);
5126 } else {
5127 _copy_non_heap_obj_cl->do_oop(p);
5128 }
5129 }
5130 } else {
5131 #ifdef G1_DEBUG
5132 gclog_or_tty->print_cr(" not in CSet");
5133 #endif // G1_DEBUG
5134 }
5135 }
5136 };
5137
5138 // Serial drain queue closure. Called as the 'complete_gc'
5139 // closure for each discovered list in some of the
5140 // reference processing phases.
5141
5142 class G1STWDrainQueueClosure: public VoidClosure {
5143 protected:
5144 G1CollectedHeap* _g1h;
5145 G1ParScanThreadState* _par_scan_state;
5146
5147 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5148
5149 public:
5150 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5151 _g1h(g1h),
5152 _par_scan_state(pss)
5153 { }
5154
5155 void do_void() {
5156 G1ParScanThreadState* const pss = par_scan_state();
5157 pss->trim_queue();
5158 }
5159 };
5160
5161 // Parallel Reference Processing closures
5162
5163 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5164 // processing during G1 evacuation pauses.
5165
5166 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5167 private:
5168 G1CollectedHeap* _g1h;
5169 RefToScanQueueSet* _queues;
5170 WorkGang* _workers;
5171 int _active_workers;
5172
5173 public:
5174 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5175 WorkGang* workers,
5176 RefToScanQueueSet *task_queues,
5177 int n_workers) :
5178 _g1h(g1h),
5179 _queues(task_queues),
5180 _workers(workers),
5181 _active_workers(n_workers)
5182 {
5183 assert(n_workers > 0, "shouldn't call this otherwise");
5184 }
5185
5186 // Executes the given task using concurrent marking worker threads.
5187 virtual void execute(ProcessTask& task);
5188 virtual void execute(EnqueueTask& task);
5189 };
5190
5191 // Gang task for possibly parallel reference processing
5192
5193 class G1STWRefProcTaskProxy: public AbstractGangTask {
5194 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5195 ProcessTask& _proc_task;
5196 G1CollectedHeap* _g1h;
5197 RefToScanQueueSet *_task_queues;
5198 ParallelTaskTerminator* _terminator;
5199
5200 public:
5201 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5202 G1CollectedHeap* g1h,
5203 RefToScanQueueSet *task_queues,
5204 ParallelTaskTerminator* terminator) :
5205 AbstractGangTask("Process reference objects in parallel"),
5206 _proc_task(proc_task),
5207 _g1h(g1h),
5208 _task_queues(task_queues),
5209 _terminator(terminator)
5210 {}
5211
5212 virtual void work(int i) {
5213 // The reference processing task executed by a single worker.
5214 ResourceMark rm;
5215 HandleMark hm;
5216
5217 G1STWIsAliveClosure is_alive(_g1h);
5218
5219 G1ParScanThreadState pss(_g1h, i);
5220
5221 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5222 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5223 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5224
5225 pss.set_evac_closure(&scan_evac_cl);
5226 pss.set_evac_failure_closure(&evac_failure_cl);
5227 pss.set_partial_scan_closure(&partial_scan_cl);
5228
5229 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5230 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5231
5232 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5233 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5234
5235 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5236 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5237
5238 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5239 // We also need to mark copied objects.
5240 copy_non_heap_cl = ©_mark_non_heap_cl;
5241 copy_perm_cl = ©_mark_perm_cl;
5242 }
5243
5244 // Keep alive closure.
5245 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5246
5247 // Complete GC closure
5248 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5249
5250 // Call the reference processing task's work routine.
5251 _proc_task.work(i, is_alive, keep_alive, drain_queue);
5252
5253 // Note we cannot assert that the refs array is empty here as not all
5254 // of the processing tasks (specifically phase2 - pp2_work) do not execute
5255 // the complete_gc closure (which ordinarily would drain the queue) so
5256 // the queue may not be empty.
5257 }
5258 };
5259
5260 // Driver routine for parallel reference processing.
5261 // Creates an instance of the ref processing gang
5262 // task and has the worker threads execute it.
5263 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5264 assert(_workers != NULL, "Need parallel worker threads.");
5265
5266 ParallelTaskTerminator terminator(_active_workers, _queues);
5267 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5268
5269 _g1h->set_par_threads(_active_workers);
5270 _workers->run_task(&proc_task_proxy);
5271 _g1h->set_par_threads(0);
5272 }
5273
5274 // Gang task for parallel reference enqueueing.
5275
5276 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5277 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5278 EnqueueTask& _enq_task;
5279
5280 public:
5281 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5282 AbstractGangTask("Enqueue reference objects in parallel"),
5283 _enq_task(enq_task)
5284 { }
5285
5286 virtual void work(int i) {
5287 _enq_task.work(i);
5288 }
5289 };
5290
5291 // Driver routine for parallel reference enqueing.
5292 // Creates an instance of the ref enqueueing gang
5293 // task and has the worker threads execute it.
5294
5295 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5296 assert(_workers != NULL, "Need parallel worker threads.");
5297
5298 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5299
5300 _g1h->set_par_threads(_active_workers);
5301 _workers->run_task(&enq_task_proxy);
5302 _g1h->set_par_threads(0);
5303 }
5304
5305 // End of weak reference support closures
5306
5307 // Abstract task used to preserve (i.e. copy) any referent objects
5308 // that are in the collection set and are pointed to by reference
5309 // objects discovered by the CM ref processor.
5310
5311 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5312 protected:
5313 G1CollectedHeap* _g1h;
5314 RefToScanQueueSet *_queues;
5315 ParallelTaskTerminator _terminator;
5316 int _n_workers;
5317
5318 public:
5319 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5320 AbstractGangTask("ParPreserveCMReferents"),
5321 _g1h(g1h),
5322 _queues(task_queues),
5323 _terminator(workers, _queues),
5324 _n_workers(workers)
5325 { }
5326
5327 void work(int i) {
5328 ResourceMark rm;
5329 HandleMark hm;
5330
5331 G1ParScanThreadState pss(_g1h, i);
5332 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss, NULL);
5333 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5334 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss, NULL);
5335
5336 pss.set_evac_closure(&scan_evac_cl);
5337 pss.set_evac_failure_closure(&evac_failure_cl);
5338 pss.set_partial_scan_closure(&partial_scan_cl);
5339
5340 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5341
5342 // Copying keep alive closure. Applied to referent objects that need
5343 // to be copied.
5344
5345 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5346 G1ParScanPermClosure only_copy_perm_cl(_g1h, &pss, NULL);
5347
5348 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5349 G1ParScanAndMarkPermClosure copy_mark_perm_cl(_g1h, &pss, NULL);
5350
5351 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5352 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5353
5354 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5355 // We also need to mark copied objects.
5356 copy_non_heap_cl = ©_mark_non_heap_cl;
5357 copy_perm_cl = ©_mark_perm_cl;
5358 }
5359
5360 // Keep alive closure.
5361 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_perm_cl, &pss);
5362
5363 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5364
5365 int limit = ReferenceProcessor::subclasses_of_ref() * rp->max_num_q();
5366 int stride = MIN2(MAX2(_n_workers, 1), limit);
5367
5368 #ifdef G1_DEBUG
5369 gclog_or_tty->print_cr("_n_workers = %d", _n_workers);
5370 gclog_or_tty->print_cr("limit = %d", limit);
5371 gclog_or_tty->print_cr("stride = %d", stride);
5372 #endif // G1_DEBUG
5373
5374 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5375 // So this must be true - but assert just in case someone decides to
5376 // change the worker ids.
5377 assert(0 <= i && i < limit, "sanity");
5378
5379 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5380 for (int idx = i; idx < limit; idx += stride) {
5381 DiscoveredList& ref_list = rp->discovered_soft_refs()[idx];
5382 #ifdef G1_DEBUG
5383 gclog_or_tty->print_cr("Worker %d: Preserving referents on %s list(%d) - "PTR_FORMAT,
5384 i, rp->list_name(idx), idx, (void*)&ref_list);
5385 #endif // G1_DEBUG
5386
5387 oop ref = ref_list.head();
5388 while (ref != ReferenceProcessor::sentinel_ref()) {
5389 #ifdef G1_DEBUG
5390 if (_g1h->obj_in_cs(ref)) {
5391 gclog_or_tty->print_cr("Boom! Worker %d: Found a reference in CS. Forwarded? %s",
5392 i, (ref->is_forwarded() ? "YES" : "NO"));
5393 }
5394 #endif // G1_DEBUG
5395
5396 HeapWord* referent_addr = java_lang_ref_Reference::referent_addr(ref);
5397 oop referent = java_lang_ref_Reference::referent(ref);
5398 if (referent != NULL) {
5399 if (UseCompressedOops) {
5400 keep_alive.do_oop((narrowOop*)referent_addr);
5401 } else {
5402 keep_alive.do_oop((oop*)referent_addr);
5403 }
5404 }
5405
5406 // get the next reference object on the discovered list.
5407 ref = java_lang_ref_Reference::discovered(ref);
5408 }
5409 }
5410
5411 // Drain the queue - which may cause stealing
5412 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5413 drain_queue.do_void();
5414
5415 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5416 assert(pss.refs()->is_empty(), "should be");
5417 }
5418 };
5419
5420 // Weak Reference processing during an evacuation pause (part 1).
5421 void G1CollectedHeap::process_discovered_references() {
5422 double ref_proc_start = os::elapsedTime();
5423
5424 ReferenceProcessor* rp = _ref_processor_stw;
5425 assert(rp->discovery_enabled(), "should have been enabled");
5426
5427 // Closure to test whether a referent is alive.
5428 G1STWIsAliveClosure is_alive(this);
5429
5430 // Even when parallel reference processing is enabled, the processing
5431 // of JNI refs is serial and performed serially by the current thread
5432 // rather than by a worker. The following PSS will be used for processing
5433 // JNI refs.
5434
5435 // Use only a single queue for this PSS.
5436 G1ParScanThreadState pss(this, 0);
5437
5438 // We do not embed a reference processor in the copying closures
5439 // while we're actually processing the discovered reference objects.
5440 G1ParScanHeapEvacClosure scan_evac_cl(this, &pss, NULL);
5441 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5442 G1ParScanPartialArrayClosure partial_scan_cl(this, &pss, NULL);
5443
5444 pss.set_evac_closure(&scan_evac_cl);
5445 pss.set_evac_failure_closure(&evac_failure_cl);
5446 pss.set_partial_scan_closure(&partial_scan_cl);
5447
5448 assert(pss.refs()->is_empty(), "pre-condition");
5449
5450 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5451 G1ParScanPermClosure only_copy_perm_cl(this, &pss, NULL);
5452
5453 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5454 G1ParScanAndMarkPermClosure copy_mark_perm_cl(this, &pss, NULL);
5455
5456 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5457 OopsInHeapRegionClosure* copy_perm_cl = &only_copy_perm_cl;
5458
5459 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5460 // We also need to mark copied objects.
5461 copy_non_heap_cl = ©_mark_non_heap_cl;
5462 copy_perm_cl = ©_mark_perm_cl;
5463 }
5464
5465 // Keep alive closure.
5466 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_perm_cl, &pss);
5467
5468 // Serial Complete GC closure
5469 G1STWDrainQueueClosure drain_queue(this, &pss);
5470
5471 // Setup the soft refs policy...
5472 rp->setup_policy(false);
5473
5474 if (!rp->processing_is_mt()) {
5475 // Serial reference processing...
5476 rp->process_discovered_references(&is_alive,
5477 &keep_alive,
5478 &drain_queue,
5479 NULL);
5480 } else {
5481 // Parallel reference processing
5482 int active_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
5483 assert(rp->num_q() == active_workers, "sanity");
5484 assert(active_workers <= rp->max_num_q(), "sanity");
5485
5486 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5487 rp->process_discovered_references(&is_alive, &keep_alive, &drain_queue, &par_task_executor);
5488 }
5489
5490 // We have completed copying any necessary live referent objects
5491 // (that were not copied during the actual pause) so we can
5492 // retire any active alloc buffers
5493 pss.retire_alloc_buffers();
5494 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5495
5496 // Any reference objects, in the collection set, that were 'discovered'
5497 // by the CM ref processor should have already been copied (either by
5498 // applying the external root copy closure to the discovered lists, or
5499 // by following an RSet entry).
5500 //
5501 // But some of the referents, that are in the collection set, that these
5502 // reference objects point to may not have been copied: the STW ref
5503 // processor would have seen that the reference object had already
5504 // been 'discovered' and would have skipped discovering the reference,
5505 // but would not have treated the reference object as a regular oop.
5506 // As a reult the copy closure would not have been applied to the
5507 // referent object.
5508 // We need to to copy these referent objects - the references will be
5509 // processed at the end of Remark.
5510
5511 int n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5512 workers()->total_workers() : 1);
5513
5514 set_par_threads(n_workers);
5515 G1ParPreserveCMReferentsTask keep_cm_referents(this, n_workers, _task_queues);
5516
5517 if (G1CollectedHeap::use_parallel_gc_threads()) {
5518 workers()->run_task(&keep_cm_referents);
5519 } else {
5520 keep_cm_referents.work(0);
5521 }
5522
5523 set_par_threads(0);
5524
5525 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5526 g1_policy()->record_ref_proc_time(ref_proc_time * 1000.0);
5527 }
5528
5529 // Weak Reference processing during an evacuation pause (part 2).
5530 void G1CollectedHeap::enqueue_discovered_references() {
5531 double ref_enq_start = os::elapsedTime();
5532
5533 ReferenceProcessor* rp = _ref_processor_stw;
5534 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5535
5536 // Now enqueue any remaining on the discovered lists on to
5537 // the pending list.
5538 if (!rp->processing_is_mt()) {
5539 // Serial reference processing...
5540 rp->enqueue_discovered_references();
5541 } else {
5542 // Parallel reference enqueuing
5543
5544 int active_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
5545 assert(rp->num_q() == active_workers, "sanity");
5546 assert(active_workers <= rp->max_num_q(), "sanity");
5547
5548 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, active_workers);
5549 rp->enqueue_discovered_references(&par_task_executor);
5550 }
5551
5552 rp->verify_no_references_recorded();
5553 assert(!rp->discovery_enabled(), "should have been disabled");
5554
5555 // FIXME
5556 // CM's referent processing also cleans up the
5557 // string table and symbol tables. Should we
5558 // do that here also?
5559
5560 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5561 g1_policy()->record_ref_enq_time(ref_enq_time * 1000.0);
5562 }
5563
5564 void G1CollectedHeap::evacuate_collection_set() {
5565 set_evacuation_failed(false);
5566
5567 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5568 concurrent_g1_refine()->set_use_cache(false);
5569 concurrent_g1_refine()->clear_hot_cache_claimed_index();
5570
5571 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
5572 set_par_threads(n_workers);
5573 G1ParTask g1_par_task(this, n_workers, _task_queues);
5574
5575 init_for_evac_failure(NULL);
5576
5577 rem_set()->prepare_for_younger_refs_iterate(true);
5578
5579 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5580 double start_par = os::elapsedTime();
5581
5582 if (G1CollectedHeap::use_parallel_gc_threads()) {
5583 // The individual threads will set their evac-failure closures.
5584 StrongRootsScope srs(this);
5585 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5586 workers()->run_task(&g1_par_task);
5587 } else {
5588 StrongRootsScope srs(this);
5589 g1_par_task.work(0);
5590 }
5591
5592 double par_time = (os::elapsedTime() - start_par) * 1000.0;
5593 g1_policy()->record_par_time(par_time);
5594 set_par_threads(0);
5595
5596 // Process any discovered reference objects - we have
5597 // to do this _before_ we retire the GC alloc regions
5598 // as we may have to copy some 'reachable' referent
5599 // objects (and their reachable sub-graphs) that were
5600 // not copied during the pause.
5601 process_discovered_references();
5602
5603 // Is this the right thing to do here? We don't save marks
5604 // on individual heap regions when we allocate from
5605 // them in parallel, so this seems like the correct place for this.
5606 retire_all_alloc_regions();
5607
5608 // Weak root processing.
5609 // Note: when JSR 292 is enabled and code blobs can contain
5610 // non-perm oops then we will need to process the code blobs
5611 // here too.
5612 {
5613 G1STWIsAliveClosure is_alive(this);
5614 G1KeepAliveClosure keep_alive(this);
5615 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5616 }
5617
5618 release_gc_alloc_regions(false /* totally */);
5619 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5620
5621 concurrent_g1_refine()->clear_hot_cache();
5622 concurrent_g1_refine()->set_use_cache(true);
5623
5624 finalize_for_evac_failure();
5625
5626 // Must do this before removing self-forwarding pointers, which clears
5627 // the per-region evac-failure flags.
5628 concurrent_mark()->complete_marking_in_collection_set();
5629
5630 if (evacuation_failed()) {
5631 remove_self_forwarding_pointers();
5632 if (PrintGCDetails) {
5633 gclog_or_tty->print(" (to-space overflow)");
5634 } else if (PrintGC) {
5635 gclog_or_tty->print("--");
5636 }
5637 }
5638
5639 // Enqueue any remaining references remaining on the STW
5640 // reference processor's discovered lists. We need to do
5641 // this after the card table is cleaned (and verified) as
5642 // the act of enqueuing entries on to the pending list
5643 // will log these updates (and dirty their associated
5644 // cards). We need these updates logged to update any
5645 // RSets.
5646 enqueue_discovered_references();
5647
5648 if (G1DeferredRSUpdate) {
5649 RedirtyLoggedCardTableEntryFastClosure redirty;
5650 dirty_card_queue_set().set_closure(&redirty);
5651 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
5652
5653 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5654 dcq.merge_bufferlists(&dirty_card_queue_set());
5655 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5656 }
5657 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5658 }
5659
5660 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
5661 size_t* pre_used,
5662 FreeRegionList* free_list,
5663 HumongousRegionSet* humongous_proxy_set,
5664 HRRSCleanupTask* hrrs_cleanup_task,
5665 bool par) {
5666 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
5667 if (hr->isHumongous()) {
5668 assert(hr->startsHumongous(), "we should only see starts humongous");
5669 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
5670 } else {
5671 free_region(hr, pre_used, free_list, par);
5672 }
5673 } else {
5674 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
5675 }
5676 }
5677
5678 void G1CollectedHeap::free_region(HeapRegion* hr,
5679 size_t* pre_used,
5680 FreeRegionList* free_list,
5681 bool par) {
5682 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5683 assert(!hr->is_empty(), "the region should not be empty");
5684 assert(free_list != NULL, "pre-condition");
5685
5686 *pre_used += hr->used();
5687 hr->hr_clear(par, true /* clear_space */);
5688 free_list->add_as_head(hr);
5689 }
5690
5691 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5692 size_t* pre_used,
5693 FreeRegionList* free_list,
5694 HumongousRegionSet* humongous_proxy_set,
5695 bool par) {
5696 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5697 assert(free_list != NULL, "pre-condition");
5698 assert(humongous_proxy_set != NULL, "pre-condition");
5699
5700 size_t hr_used = hr->used();
5701 size_t hr_capacity = hr->capacity();
5702 size_t hr_pre_used = 0;
5703 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
5704 hr->set_notHumongous();
5705 free_region(hr, &hr_pre_used, free_list, par);
5706
5707 size_t i = hr->hrs_index() + 1;
5708 size_t num = 1;
5709 while (i < n_regions()) {
5710 HeapRegion* curr_hr = region_at(i);
5711 if (!curr_hr->continuesHumongous()) {
5712 break;
5713 }
5714 curr_hr->set_notHumongous();
5715 free_region(curr_hr, &hr_pre_used, free_list, par);
5716 num += 1;
5717 i += 1;
5718 }
5719 assert(hr_pre_used == hr_used,
5720 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
5721 "should be the same", hr_pre_used, hr_used));
5722 *pre_used += hr_pre_used;
5723 }
5724
5725 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
5726 FreeRegionList* free_list,
5727 HumongousRegionSet* humongous_proxy_set,
5728 bool par) {
5729 if (pre_used > 0) {
5730 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
5731 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
5732 assert(_summary_bytes_used >= pre_used,
5733 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
5734 "should be >= pre_used: "SIZE_FORMAT,
5735 _summary_bytes_used, pre_used));
5736 _summary_bytes_used -= pre_used;
5737 }
5738 if (free_list != NULL && !free_list->is_empty()) {
5739 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5740 _free_list.add_as_head(free_list);
5741 }
5742 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
5743 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5744 _humongous_set.update_from_proxy(humongous_proxy_set);
5745 }
5746 }
5747
5748 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
5749 while (list != NULL) {
5750 guarantee( list->is_young(), "invariant" );
5751
5752 HeapWord* bottom = list->bottom();
5753 HeapWord* end = list->end();
5754 MemRegion mr(bottom, end);
5755 ct_bs->dirty(mr);
5756
5757 list = list->get_next_young_region();
5758 }
5759 }
5760
5761
5762 class G1ParCleanupCTTask : public AbstractGangTask {
5763 CardTableModRefBS* _ct_bs;
5764 G1CollectedHeap* _g1h;
5765 HeapRegion* volatile _su_head;
5766 public:
5767 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
5768 G1CollectedHeap* g1h,
5769 HeapRegion* survivor_list) :
5770 AbstractGangTask("G1 Par Cleanup CT Task"),
5771 _ct_bs(ct_bs),
5772 _g1h(g1h),
5773 _su_head(survivor_list)
5774 { }
5775
5776 void work(int i) {
5777 HeapRegion* r;
5778 while (r = _g1h->pop_dirty_cards_region()) {
5779 clear_cards(r);
5780 }
5781 // Redirty the cards of the survivor regions.
5782 dirty_list(&this->_su_head);
5783 }
5784
5785 void clear_cards(HeapRegion* r) {
5786 // Cards for Survivor regions will be dirtied later.
5787 if (!r->is_survivor()) {
5788 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5789 }
5790 }
5791
5792 void dirty_list(HeapRegion* volatile * head_ptr) {
5793 HeapRegion* head;
5794 do {
5795 // Pop region off the list.
5796 head = *head_ptr;
5797 if (head != NULL) {
5798 HeapRegion* r = (HeapRegion*)
5799 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
5800 if (r == head) {
5801 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
5802 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
5803 }
5804 }
5805 } while (*head_ptr != NULL);
5806 }
5807 };
5808
5809
5810 #ifndef PRODUCT
5811 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5812 G1CollectedHeap* _g1h;
5813 CardTableModRefBS* _ct_bs;
5814 public:
5815 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5816 : _g1h(g1h), _ct_bs(ct_bs) { }
5817 virtual bool doHeapRegion(HeapRegion* r) {
5818 if (r->is_survivor()) {
5819 _g1h->verify_dirty_region(r);
5820 } else {
5821 _g1h->verify_not_dirty_region(r);
5822 }
5823 return false;
5824 }
5825 };
5826
5827 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5828 // All of the region should be clean.
5829 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5830 MemRegion mr(hr->bottom(), hr->end());
5831 ct_bs->verify_not_dirty_region(mr);
5832 }
5833
5834 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5835 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5836 // dirty allocated blocks as they allocate them. The thread that
5837 // retires each region and replaces it with a new one will do a
5838 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5839 // not dirty that area (one less thing to have to do while holding
5840 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5841 // is dirty.
5842 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5843 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5844 ct_bs->verify_dirty_region(mr);
5845 }
5846
5847 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5848 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5849 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5850 verify_dirty_region(hr);
5851 }
5852 }
5853
5854 void G1CollectedHeap::verify_dirty_young_regions() {
5855 verify_dirty_young_list(_young_list->first_region());
5856 verify_dirty_young_list(_young_list->first_survivor_region());
5857 }
5858 #endif
5859
5860 void G1CollectedHeap::cleanUpCardTable() {
5861 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5862 double start = os::elapsedTime();
5863
5864 // Iterate over the dirty cards region list.
5865 G1ParCleanupCTTask cleanup_task(ct_bs, this,
5866 _young_list->first_survivor_region());
5867
5868 if (ParallelGCThreads > 0) {
5869 set_par_threads(workers()->total_workers());
5870 workers()->run_task(&cleanup_task);
5871 set_par_threads(0);
5872 } else {
5873 while (_dirty_cards_region_list) {
5874 HeapRegion* r = _dirty_cards_region_list;
5875 cleanup_task.clear_cards(r);
5876 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5877 if (_dirty_cards_region_list == r) {
5878 // The last region.
5879 _dirty_cards_region_list = NULL;
5880 }
5881 r->set_next_dirty_cards_region(NULL);
5882 }
5883 // now, redirty the cards of the survivor regions
5884 // (it seemed faster to do it this way, instead of iterating over
5885 // all regions and then clearing / dirtying as appropriate)
5886 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
5887 }
5888
5889 double elapsed = os::elapsedTime() - start;
5890 g1_policy()->record_clear_ct_time(elapsed * 1000.0);
5891 #ifndef PRODUCT
5892 if (G1VerifyCTCleanup || VerifyAfterGC) {
5893 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5894 heap_region_iterate(&cleanup_verifier);
5895 }
5896 #endif
5897 }
5898
5899 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5900 size_t pre_used = 0;
5901 FreeRegionList local_free_list("Local List for CSet Freeing");
5902
5903 double young_time_ms = 0.0;
5904 double non_young_time_ms = 0.0;
5905
5906 // Since the collection set is a superset of the the young list,
5907 // all we need to do to clear the young list is clear its
5908 // head and length, and unlink any young regions in the code below
5909 _young_list->clear();
5910
5911 G1CollectorPolicy* policy = g1_policy();
5912
5913 double start_sec = os::elapsedTime();
5914 bool non_young = true;
5915
5916 HeapRegion* cur = cs_head;
5917 int age_bound = -1;
5918 size_t rs_lengths = 0;
5919
5920 while (cur != NULL) {
5921 assert(!is_on_master_free_list(cur), "sanity");
5922
5923 if (non_young) {
5924 if (cur->is_young()) {
5925 double end_sec = os::elapsedTime();
5926 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5927 non_young_time_ms += elapsed_ms;
5928
5929 start_sec = os::elapsedTime();
5930 non_young = false;
5931 }
5932 } else {
5933 double end_sec = os::elapsedTime();
5934 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5935 young_time_ms += elapsed_ms;
5936
5937 start_sec = os::elapsedTime();
5938 non_young = true;
5939 }
5940
5941 rs_lengths += cur->rem_set()->occupied();
5942
5943 HeapRegion* next = cur->next_in_collection_set();
5944 assert(cur->in_collection_set(), "bad CS");
5945 cur->set_next_in_collection_set(NULL);
5946 cur->set_in_collection_set(false);
5947
5948 if (cur->is_young()) {
5949 int index = cur->young_index_in_cset();
5950 guarantee( index != -1, "invariant" );
5951 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
5952 size_t words_survived = _surviving_young_words[index];
5953 cur->record_surv_words_in_group(words_survived);
5954
5955 // At this point the we have 'popped' cur from the collection set
5956 // (linked via next_in_collection_set()) but it is still in the
5957 // young list (linked via next_young_region()). Clear the
5958 // _next_young_region field.
5959 cur->set_next_young_region(NULL);
5960 } else {
5961 int index = cur->young_index_in_cset();
5962 guarantee( index == -1, "invariant" );
5963 }
5964
5965 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5966 (!cur->is_young() && cur->young_index_in_cset() == -1),
5967 "invariant" );
5968
5969 if (!cur->evacuation_failed()) {
5970 // And the region is empty.
5971 assert(!cur->is_empty(), "Should not have empty regions in a CS.");
5972 free_region(cur, &pre_used, &local_free_list, false /* par */);
5973 } else {
5974 cur->uninstall_surv_rate_group();
5975 if (cur->is_young())
5976 cur->set_young_index_in_cset(-1);
5977 cur->set_not_young();
5978 cur->set_evacuation_failed(false);
5979 }
5980 cur = next;
5981 }
5982
5983 policy->record_max_rs_lengths(rs_lengths);
5984 policy->cset_regions_freed();
5985
5986 double end_sec = os::elapsedTime();
5987 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5988 if (non_young)
5989 non_young_time_ms += elapsed_ms;
5990 else
5991 young_time_ms += elapsed_ms;
5992
5993 update_sets_after_freeing_regions(pre_used, &local_free_list,
5994 NULL /* humongous_proxy_set */,
5995 false /* par */);
5996 policy->record_young_free_cset_time_ms(young_time_ms);
5997 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5998 }
5999
6000 // This routine is similar to the above but does not record
6001 // any policy statistics or update free lists; we are abandoning
6002 // the current incremental collection set in preparation of a
6003 // full collection. After the full GC we will start to build up
6004 // the incremental collection set again.
6005 // This is only called when we're doing a full collection
6006 // and is immediately followed by the tearing down of the young list.
6007
6008 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6009 HeapRegion* cur = cs_head;
6010
6011 while (cur != NULL) {
6012 HeapRegion* next = cur->next_in_collection_set();
6013 assert(cur->in_collection_set(), "bad CS");
6014 cur->set_next_in_collection_set(NULL);
6015 cur->set_in_collection_set(false);
6016 cur->set_young_index_in_cset(-1);
6017 cur = next;
6018 }
6019 }
6020
6021 void G1CollectedHeap::set_free_regions_coming() {
6022 if (G1ConcRegionFreeingVerbose) {
6023 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6024 "setting free regions coming");
6025 }
6026
6027 assert(!free_regions_coming(), "pre-condition");
6028 _free_regions_coming = true;
6029 }
6030
6031 void G1CollectedHeap::reset_free_regions_coming() {
6032 {
6033 assert(free_regions_coming(), "pre-condition");
6034 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6035 _free_regions_coming = false;
6036 SecondaryFreeList_lock->notify_all();
6037 }
6038
6039 if (G1ConcRegionFreeingVerbose) {
6040 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6041 "reset free regions coming");
6042 }
6043 }
6044
6045 void G1CollectedHeap::wait_while_free_regions_coming() {
6046 // Most of the time we won't have to wait, so let's do a quick test
6047 // first before we take the lock.
6048 if (!free_regions_coming()) {
6049 return;
6050 }
6051
6052 if (G1ConcRegionFreeingVerbose) {
6053 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6054 "waiting for free regions");
6055 }
6056
6057 {
6058 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6059 while (free_regions_coming()) {
6060 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6061 }
6062 }
6063
6064 if (G1ConcRegionFreeingVerbose) {
6065 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6066 "done waiting for free regions");
6067 }
6068 }
6069
6070 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6071 assert(heap_lock_held_for_gc(),
6072 "the heap lock should already be held by or for this thread");
6073 _young_list->push_region(hr);
6074 g1_policy()->set_region_short_lived(hr);
6075 }
6076
6077 class NoYoungRegionsClosure: public HeapRegionClosure {
6078 private:
6079 bool _success;
6080 public:
6081 NoYoungRegionsClosure() : _success(true) { }
6082 bool doHeapRegion(HeapRegion* r) {
6083 if (r->is_young()) {
6084 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6085 r->bottom(), r->end());
6086 _success = false;
6087 }
6088 return false;
6089 }
6090 bool success() { return _success; }
6091 };
6092
6093 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6094 bool ret = _young_list->check_list_empty(check_sample);
6095
6096 if (check_heap) {
6097 NoYoungRegionsClosure closure;
6098 heap_region_iterate(&closure);
6099 ret = ret && closure.success();
6100 }
6101
6102 return ret;
6103 }
6104
6105 void G1CollectedHeap::empty_young_list() {
6106 assert(heap_lock_held_for_gc(),
6107 "the heap lock should already be held by or for this thread");
6108 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
6109
6110 _young_list->empty_list();
6111 }
6112
6113 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
6114 bool no_allocs = true;
6115 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
6116 HeapRegion* r = _gc_alloc_regions[ap];
6117 no_allocs = r == NULL || r->saved_mark_at_top();
6118 }
6119 return no_allocs;
6120 }
6121
6122 void G1CollectedHeap::retire_all_alloc_regions() {
6123 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
6124 HeapRegion* r = _gc_alloc_regions[ap];
6125 if (r != NULL) {
6126 // Check for aliases.
6127 bool has_processed_alias = false;
6128 for (int i = 0; i < ap; ++i) {
6129 if (_gc_alloc_regions[i] == r) {
6130 has_processed_alias = true;
6131 break;
6132 }
6133 }
6134 if (!has_processed_alias) {
6135 retire_alloc_region(r, false /* par */);
6136 }
6137 }
6138 }
6139 }
6140
6141 // Done at the start of full GC.
6142 void G1CollectedHeap::tear_down_region_lists() {
6143 _free_list.remove_all();
6144 }
6145
6146 class RegionResetter: public HeapRegionClosure {
6147 G1CollectedHeap* _g1h;
6148 FreeRegionList _local_free_list;
6149
6150 public:
6151 RegionResetter() : _g1h(G1CollectedHeap::heap()),
6152 _local_free_list("Local Free List for RegionResetter") { }
6153
6154 bool doHeapRegion(HeapRegion* r) {
6155 if (r->continuesHumongous()) return false;
6156 if (r->top() > r->bottom()) {
6157 if (r->top() < r->end()) {
6158 Copy::fill_to_words(r->top(),
6159 pointer_delta(r->end(), r->top()));
6160 }
6161 } else {
6162 assert(r->is_empty(), "tautology");
6163 _local_free_list.add_as_tail(r);
6164 }
6165 return false;
6166 }
6167
6168 void update_free_lists() {
6169 _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL,
6170 false /* par */);
6171 }
6172 };
6173
6174 // Done at the end of full GC.
6175 void G1CollectedHeap::rebuild_region_lists() {
6176 // This needs to go at the end of the full GC.
6177 RegionResetter rs;
6178 heap_region_iterate(&rs);
6179 rs.update_free_lists();
6180 }
6181
6182 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6183 _refine_cte_cl->set_concurrent(concurrent);
6184 }
6185
6186 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6187 HeapRegion* hr = heap_region_containing(p);
6188 if (hr == NULL) {
6189 return is_in_permanent(p);
6190 } else {
6191 return hr->is_in(p);
6192 }
6193 }
6194
6195 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6196 bool force) {
6197 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6198 assert(!force || g1_policy()->can_expand_young_list(),
6199 "if force is true we should be able to expand the young list");
6200 bool young_list_full = g1_policy()->is_young_list_full();
6201 if (force || !young_list_full) {
6202 HeapRegion* new_alloc_region = new_region(word_size,
6203 false /* do_expand */);
6204 if (new_alloc_region != NULL) {
6205 g1_policy()->update_region_num(true /* next_is_young */);
6206 set_region_short_lived_locked(new_alloc_region);
6207 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6208 g1mm()->update_eden_counters();
6209 return new_alloc_region;
6210 }
6211 }
6212 return NULL;
6213 }
6214
6215 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6216 size_t allocated_bytes) {
6217 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6218 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6219
6220 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6221 _summary_bytes_used += allocated_bytes;
6222 _hr_printer.retire(alloc_region);
6223 }
6224
6225 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6226 bool force) {
6227 return _g1h->new_mutator_alloc_region(word_size, force);
6228 }
6229
6230 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6231 size_t allocated_bytes) {
6232 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6233 }
6234
6235 // Heap region set verification
6236
6237 class VerifyRegionListsClosure : public HeapRegionClosure {
6238 private:
6239 HumongousRegionSet* _humongous_set;
6240 FreeRegionList* _free_list;
6241 size_t _region_count;
6242
6243 public:
6244 VerifyRegionListsClosure(HumongousRegionSet* humongous_set,
6245 FreeRegionList* free_list) :
6246 _humongous_set(humongous_set), _free_list(free_list),
6247 _region_count(0) { }
6248
6249 size_t region_count() { return _region_count; }
6250
6251 bool doHeapRegion(HeapRegion* hr) {
6252 _region_count += 1;
6253
6254 if (hr->continuesHumongous()) {
6255 return false;
6256 }
6257
6258 if (hr->is_young()) {
6259 // TODO
6260 } else if (hr->startsHumongous()) {
6261 _humongous_set->verify_next_region(hr);
6262 } else if (hr->is_empty()) {
6263 _free_list->verify_next_region(hr);
6264 }
6265 return false;
6266 }
6267 };
6268
6269 HeapRegion* G1CollectedHeap::new_heap_region(size_t hrs_index,
6270 HeapWord* bottom) {
6271 HeapWord* end = bottom + HeapRegion::GrainWords;
6272 MemRegion mr(bottom, end);
6273 assert(_g1_reserved.contains(mr), "invariant");
6274 // This might return NULL if the allocation fails
6275 return new HeapRegion(hrs_index, _bot_shared, mr, true /* is_zeroed */);
6276 }
6277
6278 void G1CollectedHeap::verify_region_sets() {
6279 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6280
6281 // First, check the explicit lists.
6282 _free_list.verify();
6283 {
6284 // Given that a concurrent operation might be adding regions to
6285 // the secondary free list we have to take the lock before
6286 // verifying it.
6287 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6288 _secondary_free_list.verify();
6289 }
6290 _humongous_set.verify();
6291
6292 // If a concurrent region freeing operation is in progress it will
6293 // be difficult to correctly attributed any free regions we come
6294 // across to the correct free list given that they might belong to
6295 // one of several (free_list, secondary_free_list, any local lists,
6296 // etc.). So, if that's the case we will skip the rest of the
6297 // verification operation. Alternatively, waiting for the concurrent
6298 // operation to complete will have a non-trivial effect on the GC's
6299 // operation (no concurrent operation will last longer than the
6300 // interval between two calls to verification) and it might hide
6301 // any issues that we would like to catch during testing.
6302 if (free_regions_coming()) {
6303 return;
6304 }
6305
6306 // Make sure we append the secondary_free_list on the free_list so
6307 // that all free regions we will come across can be safely
6308 // attributed to the free_list.
6309 append_secondary_free_list_if_not_empty_with_lock();
6310
6311 // Finally, make sure that the region accounting in the lists is
6312 // consistent with what we see in the heap.
6313 _humongous_set.verify_start();
6314 _free_list.verify_start();
6315
6316 VerifyRegionListsClosure cl(&_humongous_set, &_free_list);
6317 heap_region_iterate(&cl);
6318
6319 _humongous_set.verify_end();
6320 _free_list.verify_end();
6321 }