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 // The expansion succeeded and so we should have at least one
582 // region on the free list.
583 res = _free_list.remove_head();
584 }
585 }
586 if (res != NULL) {
587 if (G1PrintHeapRegions) {
588 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT","PTR_FORMAT"], "
589 "top "PTR_FORMAT, res->hrs_index(),
590 res->bottom(), res->end(), res->top());
591 }
592 }
593 return res;
594 }
595
596 HeapRegion* G1CollectedHeap::new_gc_alloc_region(int purpose,
597 size_t word_size) {
598 HeapRegion* alloc_region = NULL;
599 if (_gc_alloc_region_counts[purpose] < g1_policy()->max_regions(purpose)) {
600 alloc_region = new_region(word_size, true /* do_expand */);
601 if (purpose == GCAllocForSurvived && alloc_region != NULL) {
602 alloc_region->set_survivor();
603 }
604 ++_gc_alloc_region_counts[purpose];
605 } else {
606 g1_policy()->note_alloc_region_limit_reached(purpose);
607 }
608 return alloc_region;
609 }
610
611 int G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
612 size_t word_size) {
613 assert(isHumongous(word_size), "word_size should be humongous");
614 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
615
616 int first = -1;
617 if (num_regions == 1) {
618 // Only one region to allocate, no need to go through the slower
619 // path. The caller will attempt the expasion if this fails, so
620 // let's not try to expand here too.
621 HeapRegion* hr = new_region(word_size, false /* do_expand */);
622 if (hr != NULL) {
623 first = hr->hrs_index();
624 } else {
625 first = -1;
626 }
627 } else {
628 // We can't allocate humongous regions while cleanupComplete() is
629 // running, since some of the regions we find to be empty might not
630 // yet be added to the free list and it is not straightforward to
631 // know which list they are on so that we can remove them. Note
632 // that we only need to do this if we need to allocate more than
633 // one region to satisfy the current humongous allocation
634 // request. If we are only allocating one region we use the common
635 // region allocation code (see above).
636 wait_while_free_regions_coming();
637 append_secondary_free_list_if_not_empty_with_lock();
638
639 if (free_regions() >= num_regions) {
640 first = _hrs->find_contiguous(num_regions);
641 if (first != -1) {
642 for (int i = first; i < first + (int) num_regions; ++i) {
643 HeapRegion* hr = _hrs->at(i);
644 assert(hr->is_empty(), "sanity");
645 assert(is_on_master_free_list(hr), "sanity");
646 hr->set_pending_removal(true);
647 }
648 _free_list.remove_all_pending(num_regions);
649 }
650 }
651 }
652 return first;
653 }
654
655 HeapWord*
656 G1CollectedHeap::humongous_obj_allocate_initialize_regions(int first,
657 size_t num_regions,
658 size_t word_size) {
659 assert(first != -1, "pre-condition");
660 assert(isHumongous(word_size), "word_size should be humongous");
661 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
662
663 // Index of last region in the series + 1.
664 int last = first + (int) num_regions;
665
666 // We need to initialize the region(s) we just discovered. This is
667 // a bit tricky given that it can happen concurrently with
668 // refinement threads refining cards on these regions and
669 // potentially wanting to refine the BOT as they are scanning
670 // those cards (this can happen shortly after a cleanup; see CR
671 // 6991377). So we have to set up the region(s) carefully and in
672 // a specific order.
673
674 // The word size sum of all the regions we will allocate.
675 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
676 assert(word_size <= word_size_sum, "sanity");
677
678 // This will be the "starts humongous" region.
679 HeapRegion* first_hr = _hrs->at(first);
680 // The header of the new object will be placed at the bottom of
681 // the first region.
682 HeapWord* new_obj = first_hr->bottom();
683 // This will be the new end of the first region in the series that
684 // should also match the end of the last region in the seriers.
685 HeapWord* new_end = new_obj + word_size_sum;
686 // This will be the new top of the first region that will reflect
687 // this allocation.
688 HeapWord* new_top = new_obj + word_size;
689
690 // First, we need to zero the header of the space that we will be
691 // allocating. When we update top further down, some refinement
692 // threads might try to scan the region. By zeroing the header we
693 // ensure that any thread that will try to scan the region will
694 // come across the zero klass word and bail out.
695 //
696 // NOTE: It would not have been correct to have used
697 // CollectedHeap::fill_with_object() and make the space look like
698 // an int array. The thread that is doing the allocation will
699 // later update the object header to a potentially different array
700 // type and, for a very short period of time, the klass and length
701 // fields will be inconsistent. This could cause a refinement
702 // thread to calculate the object size incorrectly.
703 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
704
705 // We will set up the first region as "starts humongous". This
706 // will also update the BOT covering all the regions to reflect
707 // that there is a single object that starts at the bottom of the
708 // first region.
709 first_hr->set_startsHumongous(new_top, new_end);
710
711 // Then, if there are any, we will set up the "continues
712 // humongous" regions.
713 HeapRegion* hr = NULL;
714 for (int i = first + 1; i < last; ++i) {
715 hr = _hrs->at(i);
716 hr->set_continuesHumongous(first_hr);
717 }
718 // If we have "continues humongous" regions (hr != NULL), then the
719 // end of the last one should match new_end.
720 assert(hr == NULL || hr->end() == new_end, "sanity");
721
722 // Up to this point no concurrent thread would have been able to
723 // do any scanning on any region in this series. All the top
724 // fields still point to bottom, so the intersection between
725 // [bottom,top] and [card_start,card_end] will be empty. Before we
726 // update the top fields, we'll do a storestore to make sure that
727 // no thread sees the update to top before the zeroing of the
728 // object header and the BOT initialization.
729 OrderAccess::storestore();
730
731 // Now that the BOT and the object header have been initialized,
732 // we can update top of the "starts humongous" region.
733 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
734 "new_top should be in this region");
735 first_hr->set_top(new_top);
736
737 // Now, we will update the top fields of the "continues humongous"
738 // regions. The reason we need to do this is that, otherwise,
739 // these regions would look empty and this will confuse parts of
740 // G1. For example, the code that looks for a consecutive number
741 // of empty regions will consider them empty and try to
742 // re-allocate them. We can extend is_empty() to also include
743 // !continuesHumongous(), but it is easier to just update the top
744 // fields here. The way we set top for all regions (i.e., top ==
745 // end for all regions but the last one, top == new_top for the
746 // last one) is actually used when we will free up the humongous
747 // region in free_humongous_region().
748 hr = NULL;
749 for (int i = first + 1; i < last; ++i) {
750 hr = _hrs->at(i);
751 if ((i + 1) == last) {
752 // last continues humongous region
753 assert(hr->bottom() < new_top && new_top <= hr->end(),
754 "new_top should fall on this region");
755 hr->set_top(new_top);
756 } else {
757 // not last one
758 assert(new_top > hr->end(), "new_top should be above this region");
759 hr->set_top(hr->end());
760 }
761 }
762 // If we have continues humongous regions (hr != NULL), then the
763 // end of the last one should match new_end and its top should
764 // match new_top.
765 assert(hr == NULL ||
766 (hr->end() == new_end && hr->top() == new_top), "sanity");
767
768 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
769 _summary_bytes_used += first_hr->used();
770 _humongous_set.add(first_hr);
771
772 return new_obj;
773 }
774
775 // If could fit into free regions w/o expansion, try.
776 // Otherwise, if can expand, do so.
777 // Otherwise, if using ex regions might help, try with ex given back.
778 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
779 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
780
781 verify_region_sets_optional();
782
783 size_t num_regions =
784 round_to(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
785 size_t x_size = expansion_regions();
786 size_t fs = _hrs->free_suffix();
787 int first = humongous_obj_allocate_find_first(num_regions, word_size);
788 if (first == -1) {
789 // The only thing we can do now is attempt expansion.
790 if (fs + x_size >= num_regions) {
791 // If the number of regions we're trying to allocate for this
792 // object is at most the number of regions in the free suffix,
793 // then the call to humongous_obj_allocate_find_first() above
794 // should have succeeded and we wouldn't be here.
795 //
796 // We should only be trying to expand when the free suffix is
797 // not sufficient for the object _and_ we have some expansion
798 // room available.
799 assert(num_regions > fs, "earlier allocation should have succeeded");
800
801 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
802 first = humongous_obj_allocate_find_first(num_regions, word_size);
803 // If the expansion was successful then the allocation
804 // should have been successful.
805 assert(first != -1, "this should have worked");
806 }
807 }
808 }
809
810 HeapWord* result = NULL;
811 if (first != -1) {
812 result =
813 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
814 assert(result != NULL, "it should always return a valid result");
815 }
816
817 verify_region_sets_optional();
818
819 return result;
820 }
821
822 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
823 assert_heap_not_locked_and_not_at_safepoint();
824 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
825
826 unsigned int dummy_gc_count_before;
827 return attempt_allocation(word_size, &dummy_gc_count_before);
828 }
829
830 HeapWord*
831 G1CollectedHeap::mem_allocate(size_t word_size,
832 bool is_noref,
833 bool is_tlab,
834 bool* gc_overhead_limit_was_exceeded) {
835 assert_heap_not_locked_and_not_at_safepoint();
836 assert(!is_tlab, "mem_allocate() this should not be called directly "
837 "to allocate TLABs");
838
839 // Loop until the allocation is satisified, or unsatisfied after GC.
840 for (int try_count = 1; /* we'll return */; try_count += 1) {
841 unsigned int gc_count_before;
842
843 HeapWord* result = NULL;
844 if (!isHumongous(word_size)) {
845 result = attempt_allocation(word_size, &gc_count_before);
846 } else {
847 result = attempt_allocation_humongous(word_size, &gc_count_before);
848 }
849 if (result != NULL) {
850 return result;
851 }
852
853 // Create the garbage collection operation...
854 VM_G1CollectForAllocation op(gc_count_before, word_size);
855 // ...and get the VM thread to execute it.
856 VMThread::execute(&op);
857
858 if (op.prologue_succeeded() && op.pause_succeeded()) {
859 // If the operation was successful we'll return the result even
860 // if it is NULL. If the allocation attempt failed immediately
861 // after a Full GC, it's unlikely we'll be able to allocate now.
862 HeapWord* result = op.result();
863 if (result != NULL && !isHumongous(word_size)) {
864 // Allocations that take place on VM operations do not do any
865 // card dirtying and we have to do it here. We only have to do
866 // this for non-humongous allocations, though.
867 dirty_young_block(result, word_size);
868 }
869 return result;
870 } else {
871 assert(op.result() == NULL,
872 "the result should be NULL if the VM op did not succeed");
873 }
874
875 // Give a warning if we seem to be looping forever.
876 if ((QueuedAllocationWarningCount > 0) &&
877 (try_count % QueuedAllocationWarningCount == 0)) {
878 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
879 }
880 }
881
882 ShouldNotReachHere();
883 return NULL;
884 }
885
886 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
887 unsigned int *gc_count_before_ret) {
888 // Make sure you read the note in attempt_allocation_humongous().
889
890 assert_heap_not_locked_and_not_at_safepoint();
891 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
892 "be called for humongous allocation requests");
893
894 // We should only get here after the first-level allocation attempt
895 // (attempt_allocation()) failed to allocate.
896
897 // We will loop until a) we manage to successfully perform the
898 // allocation or b) we successfully schedule a collection which
899 // fails to perform the allocation. b) is the only case when we'll
900 // return NULL.
901 HeapWord* result = NULL;
902 for (int try_count = 1; /* we'll return */; try_count += 1) {
903 bool should_try_gc;
904 unsigned int gc_count_before;
905
906 {
907 MutexLockerEx x(Heap_lock);
908
909 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
910 false /* bot_updates */);
911 if (result != NULL) {
912 return result;
913 }
914
915 // If we reach here, attempt_allocation_locked() above failed to
916 // allocate a new region. So the mutator alloc region should be NULL.
917 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
918
919 if (GC_locker::is_active_and_needs_gc()) {
920 if (g1_policy()->can_expand_young_list()) {
921 result = _mutator_alloc_region.attempt_allocation_force(word_size,
922 false /* bot_updates */);
923 if (result != NULL) {
924 return result;
925 }
926 }
927 should_try_gc = false;
928 } else {
929 // Read the GC count while still holding the Heap_lock.
930 gc_count_before = SharedHeap::heap()->total_collections();
931 should_try_gc = true;
932 }
933 }
934
935 if (should_try_gc) {
936 bool succeeded;
937 result = do_collection_pause(word_size, gc_count_before, &succeeded);
938 if (result != NULL) {
939 assert(succeeded, "only way to get back a non-NULL result");
940 return result;
941 }
942
943 if (succeeded) {
944 // If we get here we successfully scheduled a collection which
945 // failed to allocate. No point in trying to allocate
946 // further. We'll just return NULL.
947 MutexLockerEx x(Heap_lock);
948 *gc_count_before_ret = SharedHeap::heap()->total_collections();
949 return NULL;
950 }
951 } else {
952 GC_locker::stall_until_clear();
953 }
954
955 // We can reach here if we were unsuccessul in scheduling a
956 // collection (because another thread beat us to it) or if we were
957 // stalled due to the GC locker. In either can we should retry the
958 // allocation attempt in case another thread successfully
959 // performed a collection and reclaimed enough space. We do the
960 // first attempt (without holding the Heap_lock) here and the
961 // follow-on attempt will be at the start of the next loop
962 // iteration (after taking the Heap_lock).
963 result = _mutator_alloc_region.attempt_allocation(word_size,
964 false /* bot_updates */);
965 if (result != NULL ){
966 return result;
967 }
968
969 // Give a warning if we seem to be looping forever.
970 if ((QueuedAllocationWarningCount > 0) &&
971 (try_count % QueuedAllocationWarningCount == 0)) {
972 warning("G1CollectedHeap::attempt_allocation_slow() "
973 "retries %d times", try_count);
974 }
975 }
976
977 ShouldNotReachHere();
978 return NULL;
979 }
980
981 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
982 unsigned int * gc_count_before_ret) {
983 // The structure of this method has a lot of similarities to
984 // attempt_allocation_slow(). The reason these two were not merged
985 // into a single one is that such a method would require several "if
986 // allocation is not humongous do this, otherwise do that"
987 // conditional paths which would obscure its flow. In fact, an early
988 // version of this code did use a unified method which was harder to
989 // follow and, as a result, it had subtle bugs that were hard to
990 // track down. So keeping these two methods separate allows each to
991 // be more readable. It will be good to keep these two in sync as
992 // much as possible.
993
994 assert_heap_not_locked_and_not_at_safepoint();
995 assert(isHumongous(word_size), "attempt_allocation_humongous() "
996 "should only be called for humongous allocations");
997
998 // We will loop until a) we manage to successfully perform the
999 // allocation or b) we successfully schedule a collection which
1000 // fails to perform the allocation. b) is the only case when we'll
1001 // return NULL.
1002 HeapWord* result = NULL;
1003 for (int try_count = 1; /* we'll return */; try_count += 1) {
1004 bool should_try_gc;
1005 unsigned int gc_count_before;
1006
1007 {
1008 MutexLockerEx x(Heap_lock);
1009
1010 // Given that humongous objects are not allocated in young
1011 // regions, we'll first try to do the allocation without doing a
1012 // collection hoping that there's enough space in the heap.
1013 result = humongous_obj_allocate(word_size);
1014 if (result != NULL) {
1015 return result;
1016 }
1017
1018 if (GC_locker::is_active_and_needs_gc()) {
1019 should_try_gc = false;
1020 } else {
1021 // Read the GC count while still holding the Heap_lock.
1022 gc_count_before = SharedHeap::heap()->total_collections();
1023 should_try_gc = true;
1024 }
1025 }
1026
1027 if (should_try_gc) {
1028 // If we failed to allocate the humongous object, we should try to
1029 // do a collection pause (if we're allowed) in case it reclaims
1030 // enough space for the allocation to succeed after the pause.
1031
1032 bool succeeded;
1033 result = do_collection_pause(word_size, gc_count_before, &succeeded);
1034 if (result != NULL) {
1035 assert(succeeded, "only way to get back a non-NULL result");
1036 return result;
1037 }
1038
1039 if (succeeded) {
1040 // If we get here we successfully scheduled a collection which
1041 // failed to allocate. No point in trying to allocate
1042 // further. We'll just return NULL.
1043 MutexLockerEx x(Heap_lock);
1044 *gc_count_before_ret = SharedHeap::heap()->total_collections();
1045 return NULL;
1046 }
1047 } else {
1048 GC_locker::stall_until_clear();
1049 }
1050
1051 // We can reach here if we were unsuccessul in scheduling a
1052 // collection (because another thread beat us to it) or if we were
1053 // stalled due to the GC locker. In either can we should retry the
1054 // allocation attempt in case another thread successfully
1055 // performed a collection and reclaimed enough space. Give a
1056 // warning if we seem to be looping forever.
1057
1058 if ((QueuedAllocationWarningCount > 0) &&
1059 (try_count % QueuedAllocationWarningCount == 0)) {
1060 warning("G1CollectedHeap::attempt_allocation_humongous() "
1061 "retries %d times", try_count);
1062 }
1063 }
1064
1065 ShouldNotReachHere();
1066 return NULL;
1067 }
1068
1069 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1070 bool expect_null_mutator_alloc_region) {
1071 assert_at_safepoint(true /* should_be_vm_thread */);
1072 assert(_mutator_alloc_region.get() == NULL ||
1073 !expect_null_mutator_alloc_region,
1074 "the current alloc region was unexpectedly found to be non-NULL");
1075
1076 if (!isHumongous(word_size)) {
1077 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1078 false /* bot_updates */);
1079 } else {
1080 return humongous_obj_allocate(word_size);
1081 }
1082
1083 ShouldNotReachHere();
1084 }
1085
1086 void G1CollectedHeap::abandon_gc_alloc_regions() {
1087 // first, make sure that the GC alloc region list is empty (it should!)
1088 assert(_gc_alloc_region_list == NULL, "invariant");
1089 release_gc_alloc_regions(true /* totally */);
1090 }
1091
1092 class PostMCRemSetClearClosure: public HeapRegionClosure {
1093 ModRefBarrierSet* _mr_bs;
1094 public:
1095 PostMCRemSetClearClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1096 bool doHeapRegion(HeapRegion* r) {
1097 r->reset_gc_time_stamp();
1098 if (r->continuesHumongous())
1099 return false;
1100 HeapRegionRemSet* hrrs = r->rem_set();
1101 if (hrrs != NULL) hrrs->clear();
1102 // You might think here that we could clear just the cards
1103 // corresponding to the used region. But no: if we leave a dirty card
1104 // in a region we might allocate into, then it would prevent that card
1105 // from being enqueued, and cause it to be missed.
1106 // Re: the performance cost: we shouldn't be doing full GC anyway!
1107 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1108 return false;
1109 }
1110 };
1111
1112
1113 class PostMCRemSetInvalidateClosure: public HeapRegionClosure {
1114 ModRefBarrierSet* _mr_bs;
1115 public:
1116 PostMCRemSetInvalidateClosure(ModRefBarrierSet* mr_bs) : _mr_bs(mr_bs) {}
1117 bool doHeapRegion(HeapRegion* r) {
1118 if (r->continuesHumongous()) return false;
1119 if (r->used_region().word_size() != 0) {
1120 _mr_bs->invalidate(r->used_region(), true /*whole heap*/);
1121 }
1122 return false;
1123 }
1124 };
1125
1126 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1127 G1CollectedHeap* _g1h;
1128 UpdateRSOopClosure _cl;
1129 int _worker_i;
1130 public:
1131 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1132 _cl(g1->g1_rem_set(), worker_i),
1133 _worker_i(worker_i),
1134 _g1h(g1)
1135 { }
1136
1137 bool doHeapRegion(HeapRegion* r) {
1138 if (!r->continuesHumongous()) {
1139 _cl.set_from(r);
1140 r->oop_iterate(&_cl);
1141 }
1142 return false;
1143 }
1144 };
1145
1146 class ParRebuildRSTask: public AbstractGangTask {
1147 G1CollectedHeap* _g1;
1148 public:
1149 ParRebuildRSTask(G1CollectedHeap* g1)
1150 : AbstractGangTask("ParRebuildRSTask"),
1151 _g1(g1)
1152 { }
1153
1154 void work(int i) {
1155 RebuildRSOutOfRegionClosure rebuild_rs(_g1, i);
1156 _g1->heap_region_par_iterate_chunked(&rebuild_rs, i,
1157 HeapRegion::RebuildRSClaimValue);
1158 }
1159 };
1160
1161 bool G1CollectedHeap::do_collection(bool explicit_gc,
1162 bool clear_all_soft_refs,
1163 size_t word_size) {
1164 assert_at_safepoint(true /* should_be_vm_thread */);
1165
1166 if (GC_locker::check_active_before_gc()) {
1167 return false;
1168 }
1169
1170 SvcGCMarker sgcm(SvcGCMarker::FULL);
1171 ResourceMark rm;
1172
1173 if (PrintHeapAtGC) {
1174 Universe::print_heap_before_gc();
1175 }
1176
1177 verify_region_sets_optional();
1178
1179 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1180 collector_policy()->should_clear_all_soft_refs();
1181
1182 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1183
1184 {
1185 IsGCActiveMark x;
1186
1187 // Timing
1188 bool system_gc = (gc_cause() == GCCause::_java_lang_system_gc);
1189 assert(!system_gc || explicit_gc, "invariant");
1190 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
1191 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
1192 TraceTime t(system_gc ? "Full GC (System.gc())" : "Full GC",
1193 PrintGC, true, gclog_or_tty);
1194
1195 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1196 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1197
1198 double start = os::elapsedTime();
1199 g1_policy()->record_full_collection_start();
1200
1201 wait_while_free_regions_coming();
1202 append_secondary_free_list_if_not_empty_with_lock();
1203
1204 gc_prologue(true);
1205 increment_total_collections(true /* full gc */);
1206
1207 size_t g1h_prev_used = used();
1208 assert(used() == recalculate_used(), "Should be equal");
1209
1210 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
1211 HandleMark hm; // Discard invalid handles created during verification
1212 gclog_or_tty->print(" VerifyBeforeGC:");
1213 prepare_for_verify();
1214 Universe::verify(true);
1215 }
1216
1217 COMPILER2_PRESENT(DerivedPointerTable::clear());
1218
1219 // We want to discover references, but not process them yet.
1220 // This mode is disabled in
1221 // instanceRefKlass::process_discovered_references if the
1222 // generation does some collection work, or
1223 // instanceRefKlass::enqueue_discovered_references if the
1224 // generation returns without doing any work.
1225 ref_processor()->disable_discovery();
1226 ref_processor()->abandon_partial_discovery();
1227 ref_processor()->verify_no_references_recorded();
1228
1229 // Abandon current iterations of concurrent marking and concurrent
1230 // refinement, if any are in progress.
1231 concurrent_mark()->abort();
1232
1233 // Make sure we'll choose a new allocation region afterwards.
1234 release_mutator_alloc_region();
1235 abandon_gc_alloc_regions();
1236 g1_rem_set()->cleanupHRRS();
1237 tear_down_region_lists();
1238
1239 // We may have added regions to the current incremental collection
1240 // set between the last GC or pause and now. We need to clear the
1241 // incremental collection set and then start rebuilding it afresh
1242 // after this full GC.
1243 abandon_collection_set(g1_policy()->inc_cset_head());
1244 g1_policy()->clear_incremental_cset();
1245 g1_policy()->stop_incremental_cset_building();
1246
1247 if (g1_policy()->in_young_gc_mode()) {
1248 empty_young_list();
1249 g1_policy()->set_full_young_gcs(true);
1250 }
1251
1252 // See the comment in G1CollectedHeap::ref_processing_init() about
1253 // how reference processing currently works in G1.
1254
1255 // Temporarily make reference _discovery_ single threaded (non-MT).
1256 ReferenceProcessorMTDiscoveryMutator rp_disc_ser(ref_processor(), false);
1257
1258 // Temporarily make refs discovery atomic
1259 ReferenceProcessorAtomicMutator rp_disc_atomic(ref_processor(), true);
1260
1261 // Temporarily clear _is_alive_non_header
1262 ReferenceProcessorIsAliveMutator rp_is_alive_null(ref_processor(), NULL);
1263
1264 ref_processor()->enable_discovery();
1265 ref_processor()->setup_policy(do_clear_all_soft_refs);
1266
1267 // Do collection work
1268 {
1269 HandleMark hm; // Discard invalid handles created during gc
1270 G1MarkSweep::invoke_at_safepoint(ref_processor(), do_clear_all_soft_refs);
1271 }
1272 assert(free_regions() == 0, "we should not have added any free regions");
1273 rebuild_region_lists();
1274
1275 _summary_bytes_used = recalculate_used();
1276
1277 ref_processor()->enqueue_discovered_references();
1278
1279 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1280
1281 MemoryService::track_memory_usage();
1282
1283 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
1284 HandleMark hm; // Discard invalid handles created during verification
1285 gclog_or_tty->print(" VerifyAfterGC:");
1286 prepare_for_verify();
1287 Universe::verify(false);
1288 }
1289 NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1290
1291 reset_gc_time_stamp();
1292 // Since everything potentially moved, we will clear all remembered
1293 // sets, and clear all cards. Later we will rebuild remebered
1294 // sets. We will also reset the GC time stamps of the regions.
1295 PostMCRemSetClearClosure rs_clear(mr_bs());
1296 heap_region_iterate(&rs_clear);
1297
1298 // Resize the heap if necessary.
1299 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1300
1301 if (_cg1r->use_cache()) {
1302 _cg1r->clear_and_record_card_counts();
1303 _cg1r->clear_hot_cache();
1304 }
1305
1306 // Rebuild remembered sets of all regions.
1307
1308 if (G1CollectedHeap::use_parallel_gc_threads()) {
1309 ParRebuildRSTask rebuild_rs_task(this);
1310 assert(check_heap_region_claim_values(
1311 HeapRegion::InitialClaimValue), "sanity check");
1312 set_par_threads(workers()->total_workers());
1313 workers()->run_task(&rebuild_rs_task);
1314 set_par_threads(0);
1315 assert(check_heap_region_claim_values(
1316 HeapRegion::RebuildRSClaimValue), "sanity check");
1317 reset_heap_region_claim_values();
1318 } else {
1319 RebuildRSOutOfRegionClosure rebuild_rs(this);
1320 heap_region_iterate(&rebuild_rs);
1321 }
1322
1323 if (PrintGC) {
1324 print_size_transition(gclog_or_tty, g1h_prev_used, used(), capacity());
1325 }
1326
1327 if (true) { // FIXME
1328 // Ask the permanent generation to adjust size for full collections
1329 perm()->compute_new_size();
1330 }
1331
1332 // Start a new incremental collection set for the next pause
1333 assert(g1_policy()->collection_set() == NULL, "must be");
1334 g1_policy()->start_incremental_cset_building();
1335
1336 // Clear the _cset_fast_test bitmap in anticipation of adding
1337 // regions to the incremental collection set for the next
1338 // evacuation pause.
1339 clear_cset_fast_test();
1340
1341 init_mutator_alloc_region();
1342
1343 double end = os::elapsedTime();
1344 g1_policy()->record_full_collection_end();
1345
1346 #ifdef TRACESPINNING
1347 ParallelTaskTerminator::print_termination_counts();
1348 #endif
1349
1350 gc_epilogue(true);
1351
1352 // Discard all rset updates
1353 JavaThread::dirty_card_queue_set().abandon_logs();
1354 assert(!G1DeferredRSUpdate
1355 || (G1DeferredRSUpdate && (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1356 }
1357
1358 if (g1_policy()->in_young_gc_mode()) {
1359 _young_list->reset_sampled_info();
1360 // At this point there should be no regions in the
1361 // entire heap tagged as young.
1362 assert( check_young_list_empty(true /* check_heap */),
1363 "young list should be empty at this point");
1364 }
1365
1366 // Update the number of full collections that have been completed.
1367 increment_full_collections_completed(false /* concurrent */);
1368
1369 verify_region_sets_optional();
1370
1371 if (PrintHeapAtGC) {
1372 Universe::print_heap_after_gc();
1373 }
1374 g1mm()->update_counters();
1375
1376 return true;
1377 }
1378
1379 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1380 // do_collection() will return whether it succeeded in performing
1381 // the GC. Currently, there is no facility on the
1382 // do_full_collection() API to notify the caller than the collection
1383 // did not succeed (e.g., because it was locked out by the GC
1384 // locker). So, right now, we'll ignore the return value.
1385 bool dummy = do_collection(true, /* explicit_gc */
1386 clear_all_soft_refs,
1387 0 /* word_size */);
1388 }
1389
1390 // This code is mostly copied from TenuredGeneration.
1391 void
1392 G1CollectedHeap::
1393 resize_if_necessary_after_full_collection(size_t word_size) {
1394 assert(MinHeapFreeRatio <= MaxHeapFreeRatio, "sanity check");
1395
1396 // Include the current allocation, if any, and bytes that will be
1397 // pre-allocated to support collections, as "used".
1398 const size_t used_after_gc = used();
1399 const size_t capacity_after_gc = capacity();
1400 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1401
1402 // This is enforced in arguments.cpp.
1403 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1404 "otherwise the code below doesn't make sense");
1405
1406 // We don't have floating point command-line arguments
1407 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1408 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1409 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1410 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1411
1412 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1413 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1414
1415 // We have to be careful here as these two calculations can overflow
1416 // 32-bit size_t's.
1417 double used_after_gc_d = (double) used_after_gc;
1418 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1419 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1420
1421 // Let's make sure that they are both under the max heap size, which
1422 // by default will make them fit into a size_t.
1423 double desired_capacity_upper_bound = (double) max_heap_size;
1424 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1425 desired_capacity_upper_bound);
1426 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1427 desired_capacity_upper_bound);
1428
1429 // We can now safely turn them into size_t's.
1430 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1431 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1432
1433 // This assert only makes sense here, before we adjust them
1434 // with respect to the min and max heap size.
1435 assert(minimum_desired_capacity <= maximum_desired_capacity,
1436 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1437 "maximum_desired_capacity = "SIZE_FORMAT,
1438 minimum_desired_capacity, maximum_desired_capacity));
1439
1440 // Should not be greater than the heap max size. No need to adjust
1441 // it with respect to the heap min size as it's a lower bound (i.e.,
1442 // we'll try to make the capacity larger than it, not smaller).
1443 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1444 // Should not be less than the heap min size. No need to adjust it
1445 // with respect to the heap max size as it's an upper bound (i.e.,
1446 // we'll try to make the capacity smaller than it, not greater).
1447 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1448
1449 if (PrintGC && Verbose) {
1450 const double free_percentage =
1451 (double) free_after_gc / (double) capacity_after_gc;
1452 gclog_or_tty->print_cr("Computing new size after full GC ");
1453 gclog_or_tty->print_cr(" "
1454 " minimum_free_percentage: %6.2f",
1455 minimum_free_percentage);
1456 gclog_or_tty->print_cr(" "
1457 " maximum_free_percentage: %6.2f",
1458 maximum_free_percentage);
1459 gclog_or_tty->print_cr(" "
1460 " capacity: %6.1fK"
1461 " minimum_desired_capacity: %6.1fK"
1462 " maximum_desired_capacity: %6.1fK",
1463 (double) capacity_after_gc / (double) K,
1464 (double) minimum_desired_capacity / (double) K,
1465 (double) maximum_desired_capacity / (double) K);
1466 gclog_or_tty->print_cr(" "
1467 " free_after_gc: %6.1fK"
1468 " used_after_gc: %6.1fK",
1469 (double) free_after_gc / (double) K,
1470 (double) used_after_gc / (double) K);
1471 gclog_or_tty->print_cr(" "
1472 " free_percentage: %6.2f",
1473 free_percentage);
1474 }
1475 if (capacity_after_gc < minimum_desired_capacity) {
1476 // Don't expand unless it's significant
1477 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1478 if (expand(expand_bytes)) {
1479 if (PrintGC && Verbose) {
1480 gclog_or_tty->print_cr(" "
1481 " expanding:"
1482 " max_heap_size: %6.1fK"
1483 " minimum_desired_capacity: %6.1fK"
1484 " expand_bytes: %6.1fK",
1485 (double) max_heap_size / (double) K,
1486 (double) minimum_desired_capacity / (double) K,
1487 (double) expand_bytes / (double) K);
1488 }
1489 }
1490
1491 // No expansion, now see if we want to shrink
1492 } else if (capacity_after_gc > maximum_desired_capacity) {
1493 // Capacity too large, compute shrinking size
1494 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1495 shrink(shrink_bytes);
1496 if (PrintGC && Verbose) {
1497 gclog_or_tty->print_cr(" "
1498 " shrinking:"
1499 " min_heap_size: %6.1fK"
1500 " maximum_desired_capacity: %6.1fK"
1501 " shrink_bytes: %6.1fK",
1502 (double) min_heap_size / (double) K,
1503 (double) maximum_desired_capacity / (double) K,
1504 (double) shrink_bytes / (double) K);
1505 }
1506 }
1507 }
1508
1509
1510 HeapWord*
1511 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1512 bool* succeeded) {
1513 assert_at_safepoint(true /* should_be_vm_thread */);
1514
1515 *succeeded = true;
1516 // Let's attempt the allocation first.
1517 HeapWord* result =
1518 attempt_allocation_at_safepoint(word_size,
1519 false /* expect_null_mutator_alloc_region */);
1520 if (result != NULL) {
1521 assert(*succeeded, "sanity");
1522 return result;
1523 }
1524
1525 // In a G1 heap, we're supposed to keep allocation from failing by
1526 // incremental pauses. Therefore, at least for now, we'll favor
1527 // expansion over collection. (This might change in the future if we can
1528 // do something smarter than full collection to satisfy a failed alloc.)
1529 result = expand_and_allocate(word_size);
1530 if (result != NULL) {
1531 assert(*succeeded, "sanity");
1532 return result;
1533 }
1534
1535 // Expansion didn't work, we'll try to do a Full GC.
1536 bool gc_succeeded = do_collection(false, /* explicit_gc */
1537 false, /* clear_all_soft_refs */
1538 word_size);
1539 if (!gc_succeeded) {
1540 *succeeded = false;
1541 return NULL;
1542 }
1543
1544 // Retry the allocation
1545 result = attempt_allocation_at_safepoint(word_size,
1546 true /* expect_null_mutator_alloc_region */);
1547 if (result != NULL) {
1548 assert(*succeeded, "sanity");
1549 return result;
1550 }
1551
1552 // Then, try a Full GC that will collect all soft references.
1553 gc_succeeded = do_collection(false, /* explicit_gc */
1554 true, /* clear_all_soft_refs */
1555 word_size);
1556 if (!gc_succeeded) {
1557 *succeeded = false;
1558 return NULL;
1559 }
1560
1561 // Retry the allocation once more
1562 result = attempt_allocation_at_safepoint(word_size,
1563 true /* expect_null_mutator_alloc_region */);
1564 if (result != NULL) {
1565 assert(*succeeded, "sanity");
1566 return result;
1567 }
1568
1569 assert(!collector_policy()->should_clear_all_soft_refs(),
1570 "Flag should have been handled and cleared prior to this point");
1571
1572 // What else? We might try synchronous finalization later. If the total
1573 // space available is large enough for the allocation, then a more
1574 // complete compaction phase than we've tried so far might be
1575 // appropriate.
1576 assert(*succeeded, "sanity");
1577 return NULL;
1578 }
1579
1580 // Attempting to expand the heap sufficiently
1581 // to support an allocation of the given "word_size". If
1582 // successful, perform the allocation and return the address of the
1583 // allocated block, or else "NULL".
1584
1585 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1586 assert_at_safepoint(true /* should_be_vm_thread */);
1587
1588 verify_region_sets_optional();
1589
1590 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1591 if (expand(expand_bytes)) {
1592 verify_region_sets_optional();
1593 return attempt_allocation_at_safepoint(word_size,
1594 false /* expect_null_mutator_alloc_region */);
1595 }
1596 return NULL;
1597 }
1598
1599 bool G1CollectedHeap::expand(size_t expand_bytes) {
1600 size_t old_mem_size = _g1_storage.committed_size();
1601 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1602 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1603 HeapRegion::GrainBytes);
1604
1605 if (Verbose && PrintGC) {
1606 gclog_or_tty->print("Expanding garbage-first heap from %ldK by %ldK",
1607 old_mem_size/K, aligned_expand_bytes/K);
1608 }
1609
1610 HeapWord* old_end = (HeapWord*)_g1_storage.high();
1611 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1612 if (successful) {
1613 HeapWord* new_end = (HeapWord*)_g1_storage.high();
1614
1615 // Expand the committed region.
1616 _g1_committed.set_end(new_end);
1617
1618 // Tell the cardtable about the expansion.
1619 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1620
1621 // And the offset table as well.
1622 _bot_shared->resize(_g1_committed.word_size());
1623
1624 expand_bytes = aligned_expand_bytes;
1625 HeapWord* base = old_end;
1626
1627 // Create the heap regions for [old_end, new_end)
1628 while (expand_bytes > 0) {
1629 HeapWord* high = base + HeapRegion::GrainWords;
1630
1631 // Create a new HeapRegion.
1632 MemRegion mr(base, high);
1633 bool is_zeroed = !_g1_max_committed.contains(base);
1634 HeapRegion* hr = new HeapRegion(_bot_shared, mr, is_zeroed);
1635
1636 // Add it to the HeapRegionSeq.
1637 _hrs->insert(hr);
1638 _free_list.add_as_tail(hr);
1639
1640 // And we used up an expansion region to create it.
1641 _expansion_regions--;
1642
1643 expand_bytes -= HeapRegion::GrainBytes;
1644 base += HeapRegion::GrainWords;
1645 }
1646 assert(base == new_end, "sanity");
1647
1648 // Now update max_committed if necessary.
1649 _g1_max_committed.set_end(MAX2(_g1_max_committed.end(), new_end));
1650
1651 } else {
1652 // The expansion of the virtual storage space was unsuccessful.
1653 // Let's see if it was because we ran out of swap.
1654 if (G1ExitOnExpansionFailure &&
1655 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1656 // We had head room...
1657 vm_exit_out_of_memory(aligned_expand_bytes, "G1 heap expansion");
1658 }
1659 }
1660
1661 if (Verbose && PrintGC) {
1662 size_t new_mem_size = _g1_storage.committed_size();
1663 gclog_or_tty->print_cr("...%s, expanded to %ldK",
1664 (successful ? "Successful" : "Failed"),
1665 new_mem_size/K);
1666 }
1667 return successful;
1668 }
1669
1670 void G1CollectedHeap::shrink_helper(size_t shrink_bytes)
1671 {
1672 size_t old_mem_size = _g1_storage.committed_size();
1673 size_t aligned_shrink_bytes =
1674 ReservedSpace::page_align_size_down(shrink_bytes);
1675 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1676 HeapRegion::GrainBytes);
1677 size_t num_regions_deleted = 0;
1678 MemRegion mr = _hrs->shrink_by(aligned_shrink_bytes, num_regions_deleted);
1679
1680 assert(mr.end() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1681 if (mr.byte_size() > 0)
1682 _g1_storage.shrink_by(mr.byte_size());
1683 assert(mr.start() == (HeapWord*)_g1_storage.high(), "Bad shrink!");
1684
1685 _g1_committed.set_end(mr.start());
1686 _expansion_regions += num_regions_deleted;
1687
1688 // Tell the cardtable about it.
1689 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1690
1691 // And the offset table as well.
1692 _bot_shared->resize(_g1_committed.word_size());
1693
1694 HeapRegionRemSet::shrink_heap(n_regions());
1695
1696 if (Verbose && PrintGC) {
1697 size_t new_mem_size = _g1_storage.committed_size();
1698 gclog_or_tty->print_cr("Shrinking garbage-first heap from %ldK by %ldK to %ldK",
1699 old_mem_size/K, aligned_shrink_bytes/K,
1700 new_mem_size/K);
1701 }
1702 }
1703
1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705 verify_region_sets_optional();
1706
1707 release_gc_alloc_regions(true /* totally */);
1708 // Instead of tearing down / rebuilding the free lists here, we
1709 // could instead use the remove_all_pending() method on free_list to
1710 // remove only the ones that we need to remove.
1711 tear_down_region_lists(); // We will rebuild them in a moment.
1712 shrink_helper(shrink_bytes);
1713 rebuild_region_lists();
1714
1715 verify_region_sets_optional();
1716 }
1717
1718 // Public methods.
1719
1720 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1721 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1722 #endif // _MSC_VER
1723
1724
1725 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1726 SharedHeap(policy_),
1727 _g1_policy(policy_),
1728 _dirty_card_queue_set(false),
1729 _into_cset_dirty_card_queue_set(false),
1730 _is_alive_closure(this),
1731 _ref_processor(NULL),
1732 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1733 _bot_shared(NULL),
1734 _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
1735 _evac_failure_scan_stack(NULL) ,
1736 _mark_in_progress(false),
1737 _cg1r(NULL), _summary_bytes_used(0),
1738 _refine_cte_cl(NULL),
1739 _full_collection(false),
1740 _free_list("Master Free List"),
1741 _secondary_free_list("Secondary Free List"),
1742 _humongous_set("Master Humongous Set"),
1743 _free_regions_coming(false),
1744 _young_list(new YoungList(this)),
1745 _gc_time_stamp(0),
1746 _surviving_young_words(NULL),
1747 _full_collections_completed(0),
1748 _in_cset_fast_test(NULL),
1749 _in_cset_fast_test_base(NULL),
1750 _dirty_cards_region_list(NULL) {
1751 _g1h = this; // To catch bugs.
1752 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1753 vm_exit_during_initialization("Failed necessary allocation.");
1754 }
1755
1756 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1757
1758 int n_queues = MAX2((int)ParallelGCThreads, 1);
1759 _task_queues = new RefToScanQueueSet(n_queues);
1760
1761 int n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1762 assert(n_rem_sets > 0, "Invariant.");
1763
1764 HeapRegionRemSetIterator** iter_arr =
1765 NEW_C_HEAP_ARRAY(HeapRegionRemSetIterator*, n_queues);
1766 for (int i = 0; i < n_queues; i++) {
1767 iter_arr[i] = new HeapRegionRemSetIterator();
1768 }
1769 _rem_set_iterator = iter_arr;
1770
1771 for (int i = 0; i < n_queues; i++) {
1772 RefToScanQueue* q = new RefToScanQueue();
1773 q->initialize();
1774 _task_queues->register_queue(i, q);
1775 }
1776
1777 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
1778 _gc_alloc_regions[ap] = NULL;
1779 _gc_alloc_region_counts[ap] = 0;
1780 _retained_gc_alloc_regions[ap] = NULL;
1781 // by default, we do not retain a GC alloc region for each ap;
1782 // we'll override this, when appropriate, below
1783 _retain_gc_alloc_region[ap] = false;
1784 }
1785
1786 // We will try to remember the last half-full tenured region we
1787 // allocated to at the end of a collection so that we can re-use it
1788 // during the next collection.
1789 _retain_gc_alloc_region[GCAllocForTenured] = true;
1790
1791 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1792 }
1793
1794 jint G1CollectedHeap::initialize() {
1795 CollectedHeap::pre_initialize();
1796 os::enable_vtime();
1797
1798 // Necessary to satisfy locking discipline assertions.
1799
1800 MutexLocker x(Heap_lock);
1801
1802 // While there are no constraints in the GC code that HeapWordSize
1803 // be any particular value, there are multiple other areas in the
1804 // system which believe this to be true (e.g. oop->object_size in some
1805 // cases incorrectly returns the size in wordSize units rather than
1806 // HeapWordSize).
1807 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1808
1809 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1810 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1811
1812 // Ensure that the sizes are properly aligned.
1813 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1814 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1815
1816 _cg1r = new ConcurrentG1Refine();
1817
1818 // Reserve the maximum.
1819 PermanentGenerationSpec* pgs = collector_policy()->permanent_generation();
1820 // Includes the perm-gen.
1821
1822 const size_t total_reserved = max_byte_size + pgs->max_size();
1823 char* addr = Universe::preferred_heap_base(total_reserved, Universe::UnscaledNarrowOop);
1824
1825 ReservedSpace heap_rs(max_byte_size + pgs->max_size(),
1826 HeapRegion::GrainBytes,
1827 UseLargePages, addr);
1828
1829 if (UseCompressedOops) {
1830 if (addr != NULL && !heap_rs.is_reserved()) {
1831 // Failed to reserve at specified address - the requested memory
1832 // region is taken already, for example, by 'java' launcher.
1833 // Try again to reserver heap higher.
1834 addr = Universe::preferred_heap_base(total_reserved, Universe::ZeroBasedNarrowOop);
1835 ReservedSpace heap_rs0(total_reserved, HeapRegion::GrainBytes,
1836 UseLargePages, addr);
1837 if (addr != NULL && !heap_rs0.is_reserved()) {
1838 // Failed to reserve at specified address again - give up.
1839 addr = Universe::preferred_heap_base(total_reserved, Universe::HeapBasedNarrowOop);
1840 assert(addr == NULL, "");
1841 ReservedSpace heap_rs1(total_reserved, HeapRegion::GrainBytes,
1842 UseLargePages, addr);
1843 heap_rs = heap_rs1;
1844 } else {
1845 heap_rs = heap_rs0;
1846 }
1847 }
1848 }
1849
1850 if (!heap_rs.is_reserved()) {
1851 vm_exit_during_initialization("Could not reserve enough space for object heap");
1852 return JNI_ENOMEM;
1853 }
1854
1855 // It is important to do this in a way such that concurrent readers can't
1856 // temporarily think somethings in the heap. (I've actually seen this
1857 // happen in asserts: DLD.)
1858 _reserved.set_word_size(0);
1859 _reserved.set_start((HeapWord*)heap_rs.base());
1860 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
1861
1862 _expansion_regions = max_byte_size/HeapRegion::GrainBytes;
1863
1864 // Create the gen rem set (and barrier set) for the entire reserved region.
1865 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
1866 set_barrier_set(rem_set()->bs());
1867 if (barrier_set()->is_a(BarrierSet::ModRef)) {
1868 _mr_bs = (ModRefBarrierSet*)_barrier_set;
1869 } else {
1870 vm_exit_during_initialization("G1 requires a mod ref bs.");
1871 return JNI_ENOMEM;
1872 }
1873
1874 // Also create a G1 rem set.
1875 if (mr_bs()->is_a(BarrierSet::CardTableModRef)) {
1876 _g1_rem_set = new G1RemSet(this, (CardTableModRefBS*)mr_bs());
1877 } else {
1878 vm_exit_during_initialization("G1 requires a cardtable mod ref bs.");
1879 return JNI_ENOMEM;
1880 }
1881
1882 // Carve out the G1 part of the heap.
1883
1884 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1885 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
1886 g1_rs.size()/HeapWordSize);
1887 ReservedSpace perm_gen_rs = heap_rs.last_part(max_byte_size);
1888
1889 _perm_gen = pgs->init(perm_gen_rs, pgs->init_size(), rem_set());
1890
1891 _g1_storage.initialize(g1_rs, 0);
1892 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
1893 _g1_max_committed = _g1_committed;
1894 _hrs = new HeapRegionSeq(_expansion_regions);
1895 guarantee(_hrs != NULL, "Couldn't allocate HeapRegionSeq");
1896
1897 // 6843694 - ensure that the maximum region index can fit
1898 // in the remembered set structures.
1899 const size_t max_region_idx = ((size_t)1 << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1900 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1901
1902 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1903 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1904 guarantee((size_t) HeapRegion::CardsPerRegion < max_cards_per_region,
1905 "too many cards per region");
1906
1907 HeapRegionSet::set_unrealistically_long_length(max_regions() + 1);
1908
1909 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
1910 heap_word_size(init_byte_size));
1911
1912 _g1h = this;
1913
1914 _in_cset_fast_test_length = max_regions();
1915 _in_cset_fast_test_base = NEW_C_HEAP_ARRAY(bool, _in_cset_fast_test_length);
1916
1917 // We're biasing _in_cset_fast_test to avoid subtracting the
1918 // beginning of the heap every time we want to index; basically
1919 // it's the same with what we do with the card table.
1920 _in_cset_fast_test = _in_cset_fast_test_base -
1921 ((size_t) _g1_reserved.start() >> HeapRegion::LogOfHRGrainBytes);
1922
1923 // Clear the _cset_fast_test bitmap in anticipation of adding
1924 // regions to the incremental collection set for the first
1925 // evacuation pause.
1926 clear_cset_fast_test();
1927
1928 // Create the ConcurrentMark data structure and thread.
1929 // (Must do this late, so that "max_regions" is defined.)
1930 _cm = new ConcurrentMark(heap_rs, (int) max_regions());
1931 _cmThread = _cm->cmThread();
1932
1933 // Initialize the from_card cache structure of HeapRegionRemSet.
1934 HeapRegionRemSet::init_heap(max_regions());
1935
1936 // Now expand into the initial heap size.
1937 if (!expand(init_byte_size)) {
1938 vm_exit_during_initialization("Failed to allocate initial heap.");
1939 return JNI_ENOMEM;
1940 }
1941
1942 // Perform any initialization actions delegated to the policy.
1943 g1_policy()->init();
1944
1945 g1_policy()->note_start_of_mark_thread();
1946
1947 _refine_cte_cl =
1948 new RefineCardTableEntryClosure(ConcurrentG1RefineThread::sts(),
1949 g1_rem_set(),
1950 concurrent_g1_refine());
1951 JavaThread::dirty_card_queue_set().set_closure(_refine_cte_cl);
1952
1953 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1954 SATB_Q_FL_lock,
1955 G1SATBProcessCompletedThreshold,
1956 Shared_SATB_Q_lock);
1957
1958 JavaThread::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1959 DirtyCardQ_FL_lock,
1960 concurrent_g1_refine()->yellow_zone(),
1961 concurrent_g1_refine()->red_zone(),
1962 Shared_DirtyCardQ_lock);
1963
1964 if (G1DeferredRSUpdate) {
1965 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1966 DirtyCardQ_FL_lock,
1967 -1, // never trigger processing
1968 -1, // no limit on length
1969 Shared_DirtyCardQ_lock,
1970 &JavaThread::dirty_card_queue_set());
1971 }
1972
1973 // Initialize the card queue set used to hold cards containing
1974 // references into the collection set.
1975 _into_cset_dirty_card_queue_set.initialize(DirtyCardQ_CBL_mon,
1976 DirtyCardQ_FL_lock,
1977 -1, // never trigger processing
1978 -1, // no limit on length
1979 Shared_DirtyCardQ_lock,
1980 &JavaThread::dirty_card_queue_set());
1981
1982 // In case we're keeping closure specialization stats, initialize those
1983 // counts and that mechanism.
1984 SpecializationStats::clear();
1985
1986 _gc_alloc_region_list = NULL;
1987
1988 // Do later initialization work for concurrent refinement.
1989 _cg1r->init();
1990
1991 // Here we allocate the dummy full region that is required by the
1992 // G1AllocRegion class. If we don't pass an address in the reserved
1993 // space here, lots of asserts fire.
1994 MemRegion mr(_g1_reserved.start(), HeapRegion::GrainWords);
1995 HeapRegion* dummy_region = new HeapRegion(_bot_shared, mr, true);
1996 // We'll re-use the same region whether the alloc region will
1997 // require BOT updates or not and, if it doesn't, then a non-young
1998 // region will complain that it cannot support allocations without
1999 // BOT updates. So we'll tag the dummy region as young to avoid that.
2000 dummy_region->set_young();
2001 // Make sure it's full.
2002 dummy_region->set_top(dummy_region->end());
2003 G1AllocRegion::setup(this, dummy_region);
2004
2005 init_mutator_alloc_region();
2006
2007 // Do create of the monitoring and management support so that
2008 // values in the heap have been properly initialized.
2009 _g1mm = new G1MonitoringSupport(this, &_g1_storage);
2010
2011 return JNI_OK;
2012 }
2013
2014 void G1CollectedHeap::ref_processing_init() {
2015 // Reference processing in G1 currently works as follows:
2016 //
2017 // * There is only one reference processor instance that
2018 // 'spans' the entire heap. It is created by the code
2019 // below.
2020 // * Reference discovery is not enabled during an incremental
2021 // pause (see 6484982).
2022 // * Discoverered refs are not enqueued nor are they processed
2023 // during an incremental pause (see 6484982).
2024 // * Reference discovery is enabled at initial marking.
2025 // * Reference discovery is disabled and the discovered
2026 // references processed etc during remarking.
2027 // * Reference discovery is MT (see below).
2028 // * Reference discovery requires a barrier (see below).
2029 // * Reference processing is currently not MT (see 6608385).
2030 // * A full GC enables (non-MT) reference discovery and
2031 // processes any discovered references.
2032
2033 SharedHeap::ref_processing_init();
2034 MemRegion mr = reserved_region();
2035 _ref_processor =
2036 new ReferenceProcessor(mr, // span
2037 ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
2038 (int) ParallelGCThreads, // degree of mt processing
2039 ParallelGCThreads > 1 || ConcGCThreads > 1, // mt discovery
2040 (int) MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
2041 false, // Reference discovery is not atomic
2042 &_is_alive_closure, // is alive closure for efficiency
2043 true); // Setting next fields of discovered
2044 // lists requires a barrier.
2045 }
2046
2047 size_t G1CollectedHeap::capacity() const {
2048 return _g1_committed.byte_size();
2049 }
2050
2051 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2052 DirtyCardQueue* into_cset_dcq,
2053 bool concurrent,
2054 int worker_i) {
2055 // Clean cards in the hot card cache
2056 concurrent_g1_refine()->clean_up_cache(worker_i, g1_rem_set(), into_cset_dcq);
2057
2058 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2059 int n_completed_buffers = 0;
2060 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2061 n_completed_buffers++;
2062 }
2063 g1_policy()->record_update_rs_processed_buffers(worker_i,
2064 (double) n_completed_buffers);
2065 dcqs.clear_n_completed_buffers();
2066 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2067 }
2068
2069
2070 // Computes the sum of the storage used by the various regions.
2071
2072 size_t G1CollectedHeap::used() const {
2073 assert(Heap_lock->owner() != NULL,
2074 "Should be owned on this thread's behalf.");
2075 size_t result = _summary_bytes_used;
2076 // Read only once in case it is set to NULL concurrently
2077 HeapRegion* hr = _mutator_alloc_region.get();
2078 if (hr != NULL)
2079 result += hr->used();
2080 return result;
2081 }
2082
2083 size_t G1CollectedHeap::used_unlocked() const {
2084 size_t result = _summary_bytes_used;
2085 return result;
2086 }
2087
2088 class SumUsedClosure: public HeapRegionClosure {
2089 size_t _used;
2090 public:
2091 SumUsedClosure() : _used(0) {}
2092 bool doHeapRegion(HeapRegion* r) {
2093 if (!r->continuesHumongous()) {
2094 _used += r->used();
2095 }
2096 return false;
2097 }
2098 size_t result() { return _used; }
2099 };
2100
2101 size_t G1CollectedHeap::recalculate_used() const {
2102 SumUsedClosure blk;
2103 _hrs->iterate(&blk);
2104 return blk.result();
2105 }
2106
2107 #ifndef PRODUCT
2108 class SumUsedRegionsClosure: public HeapRegionClosure {
2109 size_t _num;
2110 public:
2111 SumUsedRegionsClosure() : _num(0) {}
2112 bool doHeapRegion(HeapRegion* r) {
2113 if (r->continuesHumongous() || r->used() > 0 || r->is_gc_alloc_region()) {
2114 _num += 1;
2115 }
2116 return false;
2117 }
2118 size_t result() { return _num; }
2119 };
2120
2121 size_t G1CollectedHeap::recalculate_used_regions() const {
2122 SumUsedRegionsClosure blk;
2123 _hrs->iterate(&blk);
2124 return blk.result();
2125 }
2126 #endif // PRODUCT
2127
2128 size_t G1CollectedHeap::unsafe_max_alloc() {
2129 if (free_regions() > 0) return HeapRegion::GrainBytes;
2130 // otherwise, is there space in the current allocation region?
2131
2132 // We need to store the current allocation region in a local variable
2133 // here. The problem is that this method doesn't take any locks and
2134 // there may be other threads which overwrite the current allocation
2135 // region field. attempt_allocation(), for example, sets it to NULL
2136 // and this can happen *after* the NULL check here but before the call
2137 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2138 // to be a problem in the optimized build, since the two loads of the
2139 // current allocation region field are optimized away.
2140 HeapRegion* hr = _mutator_alloc_region.get();
2141 if (hr == NULL) {
2142 return 0;
2143 }
2144 return hr->free();
2145 }
2146
2147 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2148 return
2149 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
2150 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
2151 }
2152
2153 #ifndef PRODUCT
2154 void G1CollectedHeap::allocate_dummy_regions() {
2155 // Let's fill up most of the region
2156 size_t word_size = HeapRegion::GrainWords - 1024;
2157 // And as a result the region we'll allocate will be humongous.
2158 guarantee(isHumongous(word_size), "sanity");
2159
2160 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2161 // Let's use the existing mechanism for the allocation
2162 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2163 if (dummy_obj != NULL) {
2164 MemRegion mr(dummy_obj, word_size);
2165 CollectedHeap::fill_with_object(mr);
2166 } else {
2167 // If we can't allocate once, we probably cannot allocate
2168 // again. Let's get out of the loop.
2169 break;
2170 }
2171 }
2172 }
2173 #endif // !PRODUCT
2174
2175 void G1CollectedHeap::increment_full_collections_completed(bool concurrent) {
2176 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2177
2178 // We assume that if concurrent == true, then the caller is a
2179 // concurrent thread that was joined the Suspendible Thread
2180 // Set. If there's ever a cheap way to check this, we should add an
2181 // assert here.
2182
2183 // We have already incremented _total_full_collections at the start
2184 // of the GC, so total_full_collections() represents how many full
2185 // collections have been started.
2186 unsigned int full_collections_started = total_full_collections();
2187
2188 // Given that this method is called at the end of a Full GC or of a
2189 // concurrent cycle, and those can be nested (i.e., a Full GC can
2190 // interrupt a concurrent cycle), the number of full collections
2191 // completed should be either one (in the case where there was no
2192 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2193 // behind the number of full collections started.
2194
2195 // This is the case for the inner caller, i.e. a Full GC.
2196 assert(concurrent ||
2197 (full_collections_started == _full_collections_completed + 1) ||
2198 (full_collections_started == _full_collections_completed + 2),
2199 err_msg("for inner caller (Full GC): full_collections_started = %u "
2200 "is inconsistent with _full_collections_completed = %u",
2201 full_collections_started, _full_collections_completed));
2202
2203 // This is the case for the outer caller, i.e. the concurrent cycle.
2204 assert(!concurrent ||
2205 (full_collections_started == _full_collections_completed + 1),
2206 err_msg("for outer caller (concurrent cycle): "
2207 "full_collections_started = %u "
2208 "is inconsistent with _full_collections_completed = %u",
2209 full_collections_started, _full_collections_completed));
2210
2211 _full_collections_completed += 1;
2212
2213 // We need to clear the "in_progress" flag in the CM thread before
2214 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2215 // is set) so that if a waiter requests another System.gc() it doesn't
2216 // incorrectly see that a marking cyle is still in progress.
2217 if (concurrent) {
2218 _cmThread->clear_in_progress();
2219 }
2220
2221 // This notify_all() will ensure that a thread that called
2222 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2223 // and it's waiting for a full GC to finish will be woken up. It is
2224 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2225 FullGCCount_lock->notify_all();
2226 }
2227
2228 void G1CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) {
2229 assert_at_safepoint(true /* should_be_vm_thread */);
2230 GCCauseSetter gcs(this, cause);
2231 switch (cause) {
2232 case GCCause::_heap_inspection:
2233 case GCCause::_heap_dump: {
2234 HandleMark hm;
2235 do_full_collection(false); // don't clear all soft refs
2236 break;
2237 }
2238 default: // XXX FIX ME
2239 ShouldNotReachHere(); // Unexpected use of this function
2240 }
2241 }
2242
2243 void G1CollectedHeap::collect(GCCause::Cause cause) {
2244 // The caller doesn't have the Heap_lock
2245 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
2246
2247 unsigned int gc_count_before;
2248 unsigned int full_gc_count_before;
2249 {
2250 MutexLocker ml(Heap_lock);
2251
2252 // Read the GC count while holding the Heap_lock
2253 gc_count_before = SharedHeap::heap()->total_collections();
2254 full_gc_count_before = SharedHeap::heap()->total_full_collections();
2255 }
2256
2257 if (should_do_concurrent_full_gc(cause)) {
2258 // Schedule an initial-mark evacuation pause that will start a
2259 // concurrent cycle. We're setting word_size to 0 which means that
2260 // we are not requesting a post-GC allocation.
2261 VM_G1IncCollectionPause op(gc_count_before,
2262 0, /* word_size */
2263 true, /* should_initiate_conc_mark */
2264 g1_policy()->max_pause_time_ms(),
2265 cause);
2266 VMThread::execute(&op);
2267 } else {
2268 if (cause == GCCause::_gc_locker
2269 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2270
2271 // Schedule a standard evacuation pause. We're setting word_size
2272 // to 0 which means that we are not requesting a post-GC allocation.
2273 VM_G1IncCollectionPause op(gc_count_before,
2274 0, /* word_size */
2275 false, /* should_initiate_conc_mark */
2276 g1_policy()->max_pause_time_ms(),
2277 cause);
2278 VMThread::execute(&op);
2279 } else {
2280 // Schedule a Full GC.
2281 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2282 VMThread::execute(&op);
2283 }
2284 }
2285 }
2286
2287 bool G1CollectedHeap::is_in(const void* p) const {
2288 if (_g1_committed.contains(p)) {
2289 HeapRegion* hr = _hrs->addr_to_region(p);
2290 return hr->is_in(p);
2291 } else {
2292 return _perm_gen->as_gen()->is_in(p);
2293 }
2294 }
2295
2296 // Iteration functions.
2297
2298 // Iterates an OopClosure over all ref-containing fields of objects
2299 // within a HeapRegion.
2300
2301 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2302 MemRegion _mr;
2303 OopClosure* _cl;
2304 public:
2305 IterateOopClosureRegionClosure(MemRegion mr, OopClosure* cl)
2306 : _mr(mr), _cl(cl) {}
2307 bool doHeapRegion(HeapRegion* r) {
2308 if (! r->continuesHumongous()) {
2309 r->oop_iterate(_cl);
2310 }
2311 return false;
2312 }
2313 };
2314
2315 void G1CollectedHeap::oop_iterate(OopClosure* cl, bool do_perm) {
2316 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2317 _hrs->iterate(&blk);
2318 if (do_perm) {
2319 perm_gen()->oop_iterate(cl);
2320 }
2321 }
2322
2323 void G1CollectedHeap::oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm) {
2324 IterateOopClosureRegionClosure blk(mr, cl);
2325 _hrs->iterate(&blk);
2326 if (do_perm) {
2327 perm_gen()->oop_iterate(cl);
2328 }
2329 }
2330
2331 // Iterates an ObjectClosure over all objects within a HeapRegion.
2332
2333 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2334 ObjectClosure* _cl;
2335 public:
2336 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2337 bool doHeapRegion(HeapRegion* r) {
2338 if (! r->continuesHumongous()) {
2339 r->object_iterate(_cl);
2340 }
2341 return false;
2342 }
2343 };
2344
2345 void G1CollectedHeap::object_iterate(ObjectClosure* cl, bool do_perm) {
2346 IterateObjectClosureRegionClosure blk(cl);
2347 _hrs->iterate(&blk);
2348 if (do_perm) {
2349 perm_gen()->object_iterate(cl);
2350 }
2351 }
2352
2353 void G1CollectedHeap::object_iterate_since_last_GC(ObjectClosure* cl) {
2354 // FIXME: is this right?
2355 guarantee(false, "object_iterate_since_last_GC not supported by G1 heap");
2356 }
2357
2358 // Calls a SpaceClosure on a HeapRegion.
2359
2360 class SpaceClosureRegionClosure: public HeapRegionClosure {
2361 SpaceClosure* _cl;
2362 public:
2363 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2364 bool doHeapRegion(HeapRegion* r) {
2365 _cl->do_space(r);
2366 return false;
2367 }
2368 };
2369
2370 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2371 SpaceClosureRegionClosure blk(cl);
2372 _hrs->iterate(&blk);
2373 }
2374
2375 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) {
2376 _hrs->iterate(cl);
2377 }
2378
2379 void G1CollectedHeap::heap_region_iterate_from(HeapRegion* r,
2380 HeapRegionClosure* cl) {
2381 _hrs->iterate_from(r, cl);
2382 }
2383
2384 void
2385 G1CollectedHeap::heap_region_iterate_from(int idx, HeapRegionClosure* cl) {
2386 _hrs->iterate_from(idx, cl);
2387 }
2388
2389 HeapRegion* G1CollectedHeap::region_at(size_t idx) { return _hrs->at(idx); }
2390
2391 void
2392 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2393 int worker,
2394 jint claim_value) {
2395 const size_t regions = n_regions();
2396 const size_t worker_num = (G1CollectedHeap::use_parallel_gc_threads() ? ParallelGCThreads : 1);
2397 // try to spread out the starting points of the workers
2398 const size_t start_index = regions / worker_num * (size_t) worker;
2399
2400 // each worker will actually look at all regions
2401 for (size_t count = 0; count < regions; ++count) {
2402 const size_t index = (start_index + count) % regions;
2403 assert(0 <= index && index < regions, "sanity");
2404 HeapRegion* r = region_at(index);
2405 // we'll ignore "continues humongous" regions (we'll process them
2406 // when we come across their corresponding "start humongous"
2407 // region) and regions already claimed
2408 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2409 continue;
2410 }
2411 // OK, try to claim it
2412 if (r->claimHeapRegion(claim_value)) {
2413 // success!
2414 assert(!r->continuesHumongous(), "sanity");
2415 if (r->startsHumongous()) {
2416 // If the region is "starts humongous" we'll iterate over its
2417 // "continues humongous" first; in fact we'll do them
2418 // first. The order is important. In on case, calling the
2419 // closure on the "starts humongous" region might de-allocate
2420 // and clear all its "continues humongous" regions and, as a
2421 // result, we might end up processing them twice. So, we'll do
2422 // them first (notice: most closures will ignore them anyway) and
2423 // then we'll do the "starts humongous" region.
2424 for (size_t ch_index = index + 1; ch_index < regions; ++ch_index) {
2425 HeapRegion* chr = region_at(ch_index);
2426
2427 // if the region has already been claimed or it's not
2428 // "continues humongous" we're done
2429 if (chr->claim_value() == claim_value ||
2430 !chr->continuesHumongous()) {
2431 break;
2432 }
2433
2434 // Noone should have claimed it directly. We can given
2435 // that we claimed its "starts humongous" region.
2436 assert(chr->claim_value() != claim_value, "sanity");
2437 assert(chr->humongous_start_region() == r, "sanity");
2438
2439 if (chr->claimHeapRegion(claim_value)) {
2440 // we should always be able to claim it; noone else should
2441 // be trying to claim this region
2442
2443 bool res2 = cl->doHeapRegion(chr);
2444 assert(!res2, "Should not abort");
2445
2446 // Right now, this holds (i.e., no closure that actually
2447 // does something with "continues humongous" regions
2448 // clears them). We might have to weaken it in the future,
2449 // but let's leave these two asserts here for extra safety.
2450 assert(chr->continuesHumongous(), "should still be the case");
2451 assert(chr->humongous_start_region() == r, "sanity");
2452 } else {
2453 guarantee(false, "we should not reach here");
2454 }
2455 }
2456 }
2457
2458 assert(!r->continuesHumongous(), "sanity");
2459 bool res = cl->doHeapRegion(r);
2460 assert(!res, "Should not abort");
2461 }
2462 }
2463 }
2464
2465 class ResetClaimValuesClosure: public HeapRegionClosure {
2466 public:
2467 bool doHeapRegion(HeapRegion* r) {
2468 r->set_claim_value(HeapRegion::InitialClaimValue);
2469 return false;
2470 }
2471 };
2472
2473 void
2474 G1CollectedHeap::reset_heap_region_claim_values() {
2475 ResetClaimValuesClosure blk;
2476 heap_region_iterate(&blk);
2477 }
2478
2479 #ifdef ASSERT
2480 // This checks whether all regions in the heap have the correct claim
2481 // value. I also piggy-backed on this a check to ensure that the
2482 // humongous_start_region() information on "continues humongous"
2483 // regions is correct.
2484
2485 class CheckClaimValuesClosure : public HeapRegionClosure {
2486 private:
2487 jint _claim_value;
2488 size_t _failures;
2489 HeapRegion* _sh_region;
2490 public:
2491 CheckClaimValuesClosure(jint claim_value) :
2492 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2493 bool doHeapRegion(HeapRegion* r) {
2494 if (r->claim_value() != _claim_value) {
2495 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2496 "claim value = %d, should be %d",
2497 r->bottom(), r->end(), r->claim_value(),
2498 _claim_value);
2499 ++_failures;
2500 }
2501 if (!r->isHumongous()) {
2502 _sh_region = NULL;
2503 } else if (r->startsHumongous()) {
2504 _sh_region = r;
2505 } else if (r->continuesHumongous()) {
2506 if (r->humongous_start_region() != _sh_region) {
2507 gclog_or_tty->print_cr("Region ["PTR_FORMAT","PTR_FORMAT"), "
2508 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2509 r->bottom(), r->end(),
2510 r->humongous_start_region(),
2511 _sh_region);
2512 ++_failures;
2513 }
2514 }
2515 return false;
2516 }
2517 size_t failures() {
2518 return _failures;
2519 }
2520 };
2521
2522 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2523 CheckClaimValuesClosure cl(claim_value);
2524 heap_region_iterate(&cl);
2525 return cl.failures() == 0;
2526 }
2527 #endif // ASSERT
2528
2529 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2530 HeapRegion* r = g1_policy()->collection_set();
2531 while (r != NULL) {
2532 HeapRegion* next = r->next_in_collection_set();
2533 if (cl->doHeapRegion(r)) {
2534 cl->incomplete();
2535 return;
2536 }
2537 r = next;
2538 }
2539 }
2540
2541 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2542 HeapRegionClosure *cl) {
2543 if (r == NULL) {
2544 // The CSet is empty so there's nothing to do.
2545 return;
2546 }
2547
2548 assert(r->in_collection_set(),
2549 "Start region must be a member of the collection set.");
2550 HeapRegion* cur = r;
2551 while (cur != NULL) {
2552 HeapRegion* next = cur->next_in_collection_set();
2553 if (cl->doHeapRegion(cur) && false) {
2554 cl->incomplete();
2555 return;
2556 }
2557 cur = next;
2558 }
2559 cur = g1_policy()->collection_set();
2560 while (cur != r) {
2561 HeapRegion* next = cur->next_in_collection_set();
2562 if (cl->doHeapRegion(cur) && false) {
2563 cl->incomplete();
2564 return;
2565 }
2566 cur = next;
2567 }
2568 }
2569
2570 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2571 return _hrs->length() > 0 ? _hrs->at(0) : NULL;
2572 }
2573
2574
2575 Space* G1CollectedHeap::space_containing(const void* addr) const {
2576 Space* res = heap_region_containing(addr);
2577 if (res == NULL)
2578 res = perm_gen()->space_containing(addr);
2579 return res;
2580 }
2581
2582 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2583 Space* sp = space_containing(addr);
2584 if (sp != NULL) {
2585 return sp->block_start(addr);
2586 }
2587 return NULL;
2588 }
2589
2590 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2591 Space* sp = space_containing(addr);
2592 assert(sp != NULL, "block_size of address outside of heap");
2593 return sp->block_size(addr);
2594 }
2595
2596 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2597 Space* sp = space_containing(addr);
2598 return sp->block_is_obj(addr);
2599 }
2600
2601 bool G1CollectedHeap::supports_tlab_allocation() const {
2602 return true;
2603 }
2604
2605 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2606 return HeapRegion::GrainBytes;
2607 }
2608
2609 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2610 // Return the remaining space in the cur alloc region, but not less than
2611 // the min TLAB size.
2612
2613 // Also, this value can be at most the humongous object threshold,
2614 // since we can't allow tlabs to grow big enough to accomodate
2615 // humongous objects.
2616
2617 HeapRegion* hr = _mutator_alloc_region.get();
2618 size_t max_tlab_size = _humongous_object_threshold_in_words * wordSize;
2619 if (hr == NULL) {
2620 return max_tlab_size;
2621 } else {
2622 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab_size);
2623 }
2624 }
2625
2626 size_t G1CollectedHeap::large_typearray_limit() {
2627 // FIXME
2628 return HeapRegion::GrainBytes/HeapWordSize;
2629 }
2630
2631 size_t G1CollectedHeap::max_capacity() const {
2632 return _g1_reserved.byte_size();
2633 }
2634
2635 jlong G1CollectedHeap::millis_since_last_gc() {
2636 // assert(false, "NYI");
2637 return 0;
2638 }
2639
2640 void G1CollectedHeap::prepare_for_verify() {
2641 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2642 ensure_parsability(false);
2643 }
2644 g1_rem_set()->prepare_for_verify();
2645 }
2646
2647 class VerifyLivenessOopClosure: public OopClosure {
2648 G1CollectedHeap* g1h;
2649 public:
2650 VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
2651 g1h = _g1h;
2652 }
2653 void do_oop(narrowOop *p) { do_oop_work(p); }
2654 void do_oop( oop *p) { do_oop_work(p); }
2655
2656 template <class T> void do_oop_work(T *p) {
2657 oop obj = oopDesc::load_decode_heap_oop(p);
2658 guarantee(obj == NULL || !g1h->is_obj_dead(obj),
2659 "Dead object referenced by a not dead object");
2660 }
2661 };
2662
2663 class VerifyObjsInRegionClosure: public ObjectClosure {
2664 private:
2665 G1CollectedHeap* _g1h;
2666 size_t _live_bytes;
2667 HeapRegion *_hr;
2668 bool _use_prev_marking;
2669 public:
2670 // use_prev_marking == true -> use "prev" marking information,
2671 // use_prev_marking == false -> use "next" marking information
2672 VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
2673 : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
2674 _g1h = G1CollectedHeap::heap();
2675 }
2676 void do_object(oop o) {
2677 VerifyLivenessOopClosure isLive(_g1h);
2678 assert(o != NULL, "Huh?");
2679 if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
2680 o->oop_iterate(&isLive);
2681 if (!_hr->obj_allocated_since_prev_marking(o)) {
2682 size_t obj_size = o->size(); // Make sure we don't overflow
2683 _live_bytes += (obj_size * HeapWordSize);
2684 }
2685 }
2686 }
2687 size_t live_bytes() { return _live_bytes; }
2688 };
2689
2690 class PrintObjsInRegionClosure : public ObjectClosure {
2691 HeapRegion *_hr;
2692 G1CollectedHeap *_g1;
2693 public:
2694 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2695 _g1 = G1CollectedHeap::heap();
2696 };
2697
2698 void do_object(oop o) {
2699 if (o != NULL) {
2700 HeapWord *start = (HeapWord *) o;
2701 size_t word_sz = o->size();
2702 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2703 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2704 (void*) o, word_sz,
2705 _g1->isMarkedPrev(o),
2706 _g1->isMarkedNext(o),
2707 _hr->obj_allocated_since_prev_marking(o));
2708 HeapWord *end = start + word_sz;
2709 HeapWord *cur;
2710 int *val;
2711 for (cur = start; cur < end; cur++) {
2712 val = (int *) cur;
2713 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
2714 }
2715 }
2716 }
2717 };
2718
2719 class VerifyRegionClosure: public HeapRegionClosure {
2720 private:
2721 bool _allow_dirty;
2722 bool _par;
2723 bool _use_prev_marking;
2724 bool _failures;
2725 public:
2726 // use_prev_marking == true -> use "prev" marking information,
2727 // use_prev_marking == false -> use "next" marking information
2728 VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
2729 : _allow_dirty(allow_dirty),
2730 _par(par),
2731 _use_prev_marking(use_prev_marking),
2732 _failures(false) {}
2733
2734 bool failures() {
2735 return _failures;
2736 }
2737
2738 bool doHeapRegion(HeapRegion* r) {
2739 guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
2740 "Should be unclaimed at verify points.");
2741 if (!r->continuesHumongous()) {
2742 bool failures = false;
2743 r->verify(_allow_dirty, _use_prev_marking, &failures);
2744 if (failures) {
2745 _failures = true;
2746 } else {
2747 VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
2748 r->object_iterate(¬_dead_yet_cl);
2749 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2750 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2751 "max_live_bytes "SIZE_FORMAT" "
2752 "< calculated "SIZE_FORMAT,
2753 r->bottom(), r->end(),
2754 r->max_live_bytes(),
2755 not_dead_yet_cl.live_bytes());
2756 _failures = true;
2757 }
2758 }
2759 }
2760 return false; // stop the region iteration if we hit a failure
2761 }
2762 };
2763
2764 class VerifyRootsClosure: public OopsInGenClosure {
2765 private:
2766 G1CollectedHeap* _g1h;
2767 bool _use_prev_marking;
2768 bool _failures;
2769 public:
2770 // use_prev_marking == true -> use "prev" marking information,
2771 // use_prev_marking == false -> use "next" marking information
2772 VerifyRootsClosure(bool use_prev_marking) :
2773 _g1h(G1CollectedHeap::heap()),
2774 _use_prev_marking(use_prev_marking),
2775 _failures(false) { }
2776
2777 bool failures() { return _failures; }
2778
2779 template <class T> void do_oop_nv(T* p) {
2780 T heap_oop = oopDesc::load_heap_oop(p);
2781 if (!oopDesc::is_null(heap_oop)) {
2782 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2783 if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
2784 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2785 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2786 obj->print_on(gclog_or_tty);
2787 _failures = true;
2788 }
2789 }
2790 }
2791
2792 void do_oop(oop* p) { do_oop_nv(p); }
2793 void do_oop(narrowOop* p) { do_oop_nv(p); }
2794 };
2795
2796 // This is the task used for parallel heap verification.
2797
2798 class G1ParVerifyTask: public AbstractGangTask {
2799 private:
2800 G1CollectedHeap* _g1h;
2801 bool _allow_dirty;
2802 bool _use_prev_marking;
2803 bool _failures;
2804
2805 public:
2806 // use_prev_marking == true -> use "prev" marking information,
2807 // use_prev_marking == false -> use "next" marking information
2808 G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
2809 bool use_prev_marking) :
2810 AbstractGangTask("Parallel verify task"),
2811 _g1h(g1h),
2812 _allow_dirty(allow_dirty),
2813 _use_prev_marking(use_prev_marking),
2814 _failures(false) { }
2815
2816 bool failures() {
2817 return _failures;
2818 }
2819
2820 void work(int worker_i) {
2821 HandleMark hm;
2822 VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
2823 _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
2824 HeapRegion::ParVerifyClaimValue);
2825 if (blk.failures()) {
2826 _failures = true;
2827 }
2828 }
2829 };
2830
2831 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
2832 verify(allow_dirty, silent, /* use_prev_marking */ true);
2833 }
2834
2835 void G1CollectedHeap::verify(bool allow_dirty,
2836 bool silent,
2837 bool use_prev_marking) {
2838 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2839 if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
2840 VerifyRootsClosure rootsCl(use_prev_marking);
2841 CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
2842 // We apply the relevant closures to all the oops in the
2843 // system dictionary, the string table and the code cache.
2844 const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
2845 process_strong_roots(true, // activate StrongRootsScope
2846 true, // we set "collecting perm gen" to true,
2847 // so we don't reset the dirty cards in the perm gen.
2848 SharedHeap::ScanningOption(so), // roots scanning options
2849 &rootsCl,
2850 &blobsCl,
2851 &rootsCl);
2852 // Since we used "collecting_perm_gen" == true above, we will not have
2853 // checked the refs from perm into the G1-collected heap. We check those
2854 // references explicitly below. Whether the relevant cards are dirty
2855 // is checked further below in the rem set verification.
2856 if (!silent) { gclog_or_tty->print("Permgen roots "); }
2857 perm_gen()->oop_iterate(&rootsCl);
2858 bool failures = rootsCl.failures();
2859 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
2860 verify_region_sets();
2861 if (!silent) { gclog_or_tty->print("HeapRegions "); }
2862 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
2863 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2864 "sanity check");
2865
2866 G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
2867 int n_workers = workers()->total_workers();
2868 set_par_threads(n_workers);
2869 workers()->run_task(&task);
2870 set_par_threads(0);
2871 if (task.failures()) {
2872 failures = true;
2873 }
2874
2875 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
2876 "sanity check");
2877
2878 reset_heap_region_claim_values();
2879
2880 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
2881 "sanity check");
2882 } else {
2883 VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
2884 _hrs->iterate(&blk);
2885 if (blk.failures()) {
2886 failures = true;
2887 }
2888 }
2889 if (!silent) gclog_or_tty->print("RemSet ");
2890 rem_set()->verify();
2891
2892 if (failures) {
2893 gclog_or_tty->print_cr("Heap:");
2894 print_on(gclog_or_tty, true /* extended */);
2895 gclog_or_tty->print_cr("");
2896 #ifndef PRODUCT
2897 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
2898 concurrent_mark()->print_reachable("at-verification-failure",
2899 use_prev_marking, false /* all */);
2900 }
2901 #endif
2902 gclog_or_tty->flush();
2903 }
2904 guarantee(!failures, "there should not have been any failures");
2905 } else {
2906 if (!silent) gclog_or_tty->print("(SKIPPING roots, heapRegions, remset) ");
2907 }
2908 }
2909
2910 class PrintRegionClosure: public HeapRegionClosure {
2911 outputStream* _st;
2912 public:
2913 PrintRegionClosure(outputStream* st) : _st(st) {}
2914 bool doHeapRegion(HeapRegion* r) {
2915 r->print_on(_st);
2916 return false;
2917 }
2918 };
2919
2920 void G1CollectedHeap::print() const { print_on(tty); }
2921
2922 void G1CollectedHeap::print_on(outputStream* st) const {
2923 print_on(st, PrintHeapAtGCExtended);
2924 }
2925
2926 void G1CollectedHeap::print_on(outputStream* st, bool extended) const {
2927 st->print(" %-20s", "garbage-first heap");
2928 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2929 capacity()/K, used_unlocked()/K);
2930 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
2931 _g1_storage.low_boundary(),
2932 _g1_storage.high(),
2933 _g1_storage.high_boundary());
2934 st->cr();
2935 st->print(" region size " SIZE_FORMAT "K, ",
2936 HeapRegion::GrainBytes/K);
2937 size_t young_regions = _young_list->length();
2938 st->print(SIZE_FORMAT " young (" SIZE_FORMAT "K), ",
2939 young_regions, young_regions * HeapRegion::GrainBytes / K);
2940 size_t survivor_regions = g1_policy()->recorded_survivor_regions();
2941 st->print(SIZE_FORMAT " survivors (" SIZE_FORMAT "K)",
2942 survivor_regions, survivor_regions * HeapRegion::GrainBytes / K);
2943 st->cr();
2944 perm()->as_gen()->print_on(st);
2945 if (extended) {
2946 st->cr();
2947 print_on_extended(st);
2948 }
2949 }
2950
2951 void G1CollectedHeap::print_on_extended(outputStream* st) const {
2952 PrintRegionClosure blk(st);
2953 _hrs->iterate(&blk);
2954 }
2955
2956 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2957 if (G1CollectedHeap::use_parallel_gc_threads()) {
2958 workers()->print_worker_threads_on(st);
2959 }
2960 _cmThread->print_on(st);
2961 st->cr();
2962 _cm->print_worker_threads_on(st);
2963 _cg1r->print_worker_threads_on(st);
2964 st->cr();
2965 }
2966
2967 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2968 if (G1CollectedHeap::use_parallel_gc_threads()) {
2969 workers()->threads_do(tc);
2970 }
2971 tc->do_thread(_cmThread);
2972 _cg1r->threads_do(tc);
2973 }
2974
2975 void G1CollectedHeap::print_tracing_info() const {
2976 // We'll overload this to mean "trace GC pause statistics."
2977 if (TraceGen0Time || TraceGen1Time) {
2978 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2979 // to that.
2980 g1_policy()->print_tracing_info();
2981 }
2982 if (G1SummarizeRSetStats) {
2983 g1_rem_set()->print_summary_info();
2984 }
2985 if (G1SummarizeConcMark) {
2986 concurrent_mark()->print_summary_info();
2987 }
2988 g1_policy()->print_yg_surv_rate_info();
2989 SpecializationStats::print();
2990 }
2991
2992 int G1CollectedHeap::addr_to_arena_id(void* addr) const {
2993 HeapRegion* hr = heap_region_containing(addr);
2994 if (hr == NULL) {
2995 return 0;
2996 } else {
2997 return 1;
2998 }
2999 }
3000
3001 G1CollectedHeap* G1CollectedHeap::heap() {
3002 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3003 "not a garbage-first heap");
3004 return _g1h;
3005 }
3006
3007 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3008 // always_do_update_barrier = false;
3009 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3010 // Call allocation profiler
3011 AllocationProfiler::iterate_since_last_gc();
3012 // Fill TLAB's and such
3013 ensure_parsability(true);
3014 }
3015
3016 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3017 // FIXME: what is this about?
3018 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3019 // is set.
3020 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3021 "derived pointer present"));
3022 // always_do_update_barrier = true;
3023 }
3024
3025 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3026 unsigned int gc_count_before,
3027 bool* succeeded) {
3028 assert_heap_not_locked_and_not_at_safepoint();
3029 g1_policy()->record_stop_world_start();
3030 VM_G1IncCollectionPause op(gc_count_before,
3031 word_size,
3032 false, /* should_initiate_conc_mark */
3033 g1_policy()->max_pause_time_ms(),
3034 GCCause::_g1_inc_collection_pause);
3035 VMThread::execute(&op);
3036
3037 HeapWord* result = op.result();
3038 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3039 assert(result == NULL || ret_succeeded,
3040 "the result should be NULL if the VM did not succeed");
3041 *succeeded = ret_succeeded;
3042
3043 assert_heap_not_locked();
3044 return result;
3045 }
3046
3047 void
3048 G1CollectedHeap::doConcurrentMark() {
3049 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3050 if (!_cmThread->in_progress()) {
3051 _cmThread->set_started();
3052 CGC_lock->notify();
3053 }
3054 }
3055
3056 class VerifyMarkedObjsClosure: public ObjectClosure {
3057 G1CollectedHeap* _g1h;
3058 public:
3059 VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
3060 void do_object(oop obj) {
3061 assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
3062 "markandsweep mark should agree with concurrent deadness");
3063 }
3064 };
3065
3066 void
3067 G1CollectedHeap::checkConcurrentMark() {
3068 VerifyMarkedObjsClosure verifycl(this);
3069 // MutexLockerEx x(getMarkBitMapLock(),
3070 // Mutex::_no_safepoint_check_flag);
3071 object_iterate(&verifycl, false);
3072 }
3073
3074 void G1CollectedHeap::do_sync_mark() {
3075 _cm->checkpointRootsInitial();
3076 _cm->markFromRoots();
3077 _cm->checkpointRootsFinal(false);
3078 }
3079
3080 // <NEW PREDICTION>
3081
3082 double G1CollectedHeap::predict_region_elapsed_time_ms(HeapRegion *hr,
3083 bool young) {
3084 return _g1_policy->predict_region_elapsed_time_ms(hr, young);
3085 }
3086
3087 void G1CollectedHeap::check_if_region_is_too_expensive(double
3088 predicted_time_ms) {
3089 _g1_policy->check_if_region_is_too_expensive(predicted_time_ms);
3090 }
3091
3092 size_t G1CollectedHeap::pending_card_num() {
3093 size_t extra_cards = 0;
3094 JavaThread *curr = Threads::first();
3095 while (curr != NULL) {
3096 DirtyCardQueue& dcq = curr->dirty_card_queue();
3097 extra_cards += dcq.size();
3098 curr = curr->next();
3099 }
3100 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3101 size_t buffer_size = dcqs.buffer_size();
3102 size_t buffer_num = dcqs.completed_buffers_num();
3103 return buffer_size * buffer_num + extra_cards;
3104 }
3105
3106 size_t G1CollectedHeap::max_pending_card_num() {
3107 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3108 size_t buffer_size = dcqs.buffer_size();
3109 size_t buffer_num = dcqs.completed_buffers_num();
3110 int thread_num = Threads::number_of_threads();
3111 return (buffer_num + thread_num) * buffer_size;
3112 }
3113
3114 size_t G1CollectedHeap::cards_scanned() {
3115 return g1_rem_set()->cardsScanned();
3116 }
3117
3118 void
3119 G1CollectedHeap::setup_surviving_young_words() {
3120 guarantee( _surviving_young_words == NULL, "pre-condition" );
3121 size_t array_length = g1_policy()->young_cset_length();
3122 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, array_length);
3123 if (_surviving_young_words == NULL) {
3124 vm_exit_out_of_memory(sizeof(size_t) * array_length,
3125 "Not enough space for young surv words summary.");
3126 }
3127 memset(_surviving_young_words, 0, array_length * sizeof(size_t));
3128 #ifdef ASSERT
3129 for (size_t i = 0; i < array_length; ++i) {
3130 assert( _surviving_young_words[i] == 0, "memset above" );
3131 }
3132 #endif // !ASSERT
3133 }
3134
3135 void
3136 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3137 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3138 size_t array_length = g1_policy()->young_cset_length();
3139 for (size_t i = 0; i < array_length; ++i)
3140 _surviving_young_words[i] += surv_young_words[i];
3141 }
3142
3143 void
3144 G1CollectedHeap::cleanup_surviving_young_words() {
3145 guarantee( _surviving_young_words != NULL, "pre-condition" );
3146 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3147 _surviving_young_words = NULL;
3148 }
3149
3150 // </NEW PREDICTION>
3151
3152 struct PrepareForRSScanningClosure : public HeapRegionClosure {
3153 bool doHeapRegion(HeapRegion *r) {
3154 r->rem_set()->set_iter_claimed(0);
3155 return false;
3156 }
3157 };
3158
3159 #if TASKQUEUE_STATS
3160 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3161 st->print_raw_cr("GC Task Stats");
3162 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3163 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3164 }
3165
3166 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3167 print_taskqueue_stats_hdr(st);
3168
3169 TaskQueueStats totals;
3170 const int n = workers() != NULL ? workers()->total_workers() : 1;
3171 for (int i = 0; i < n; ++i) {
3172 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3173 totals += task_queue(i)->stats;
3174 }
3175 st->print_raw("tot "); totals.print(st); st->cr();
3176
3177 DEBUG_ONLY(totals.verify());
3178 }
3179
3180 void G1CollectedHeap::reset_taskqueue_stats() {
3181 const int n = workers() != NULL ? workers()->total_workers() : 1;
3182 for (int i = 0; i < n; ++i) {
3183 task_queue(i)->stats.reset();
3184 }
3185 }
3186 #endif // TASKQUEUE_STATS
3187
3188 bool
3189 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3190 assert_at_safepoint(true /* should_be_vm_thread */);
3191 guarantee(!is_gc_active(), "collection is not reentrant");
3192
3193 if (GC_locker::check_active_before_gc()) {
3194 return false;
3195 }
3196
3197 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3198 ResourceMark rm;
3199
3200 if (PrintHeapAtGC) {
3201 Universe::print_heap_before_gc();
3202 }
3203
3204 verify_region_sets_optional();
3205 verify_dirty_young_regions();
3206
3207 {
3208 // This call will decide whether this pause is an initial-mark
3209 // pause. If it is, during_initial_mark_pause() will return true
3210 // for the duration of this pause.
3211 g1_policy()->decide_on_conc_mark_initiation();
3212
3213 char verbose_str[128];
3214 sprintf(verbose_str, "GC pause ");
3215 if (g1_policy()->in_young_gc_mode()) {
3216 if (g1_policy()->full_young_gcs())
3217 strcat(verbose_str, "(young)");
3218 else
3219 strcat(verbose_str, "(partial)");
3220 }
3221 if (g1_policy()->during_initial_mark_pause()) {
3222 strcat(verbose_str, " (initial-mark)");
3223 // We are about to start a marking cycle, so we increment the
3224 // full collection counter.
3225 increment_total_full_collections();
3226 }
3227
3228 // if PrintGCDetails is on, we'll print long statistics information
3229 // in the collector policy code, so let's not print this as the output
3230 // is messy if we do.
3231 gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
3232 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
3233 TraceTime t(verbose_str, PrintGC && !PrintGCDetails, true, gclog_or_tty);
3234
3235 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3236 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3237
3238 // If the secondary_free_list is not empty, append it to the
3239 // free_list. No need to wait for the cleanup operation to finish;
3240 // the region allocation code will check the secondary_free_list
3241 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3242 // set, skip this step so that the region allocation code has to
3243 // get entries from the secondary_free_list.
3244 if (!G1StressConcRegionFreeing) {
3245 append_secondary_free_list_if_not_empty_with_lock();
3246 }
3247
3248 increment_gc_time_stamp();
3249
3250 if (g1_policy()->in_young_gc_mode()) {
3251 assert(check_young_list_well_formed(),
3252 "young list should be well formed");
3253 }
3254
3255 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3256 IsGCActiveMark x;
3257
3258 gc_prologue(false);
3259 increment_total_collections(false /* full gc */);
3260
3261 #if G1_REM_SET_LOGGING
3262 gclog_or_tty->print_cr("\nJust chose CS, heap:");
3263 print();
3264 #endif
3265
3266 if (VerifyBeforeGC && total_collections() >= VerifyGCStartAt) {
3267 HandleMark hm; // Discard invalid handles created during verification
3268 gclog_or_tty->print(" VerifyBeforeGC:");
3269 prepare_for_verify();
3270 Universe::verify(false);
3271 }
3272
3273 COMPILER2_PRESENT(DerivedPointerTable::clear());
3274
3275 // Please see comment in G1CollectedHeap::ref_processing_init()
3276 // to see how reference processing currently works in G1.
3277 //
3278 // We want to turn off ref discovery, if necessary, and turn it back on
3279 // on again later if we do. XXX Dubious: why is discovery disabled?
3280 bool was_enabled = ref_processor()->discovery_enabled();
3281 if (was_enabled) ref_processor()->disable_discovery();
3282
3283 // Forget the current alloc region (we might even choose it to be part
3284 // of the collection set!).
3285 release_mutator_alloc_region();
3286
3287 // The elapsed time induced by the start time below deliberately elides
3288 // the possible verification above.
3289 double start_time_sec = os::elapsedTime();
3290 size_t start_used_bytes = used();
3291
3292 #if YOUNG_LIST_VERBOSE
3293 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3294 _young_list->print();
3295 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3296 #endif // YOUNG_LIST_VERBOSE
3297
3298 g1_policy()->record_collection_pause_start(start_time_sec,
3299 start_used_bytes);
3300
3301 #if YOUNG_LIST_VERBOSE
3302 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3303 _young_list->print();
3304 #endif // YOUNG_LIST_VERBOSE
3305
3306 if (g1_policy()->during_initial_mark_pause()) {
3307 concurrent_mark()->checkpointRootsInitialPre();
3308 }
3309 save_marks();
3310
3311 // We must do this before any possible evacuation that should propagate
3312 // marks.
3313 if (mark_in_progress()) {
3314 double start_time_sec = os::elapsedTime();
3315
3316 _cm->drainAllSATBBuffers();
3317 double finish_mark_ms = (os::elapsedTime() - start_time_sec) * 1000.0;
3318 g1_policy()->record_satb_drain_time(finish_mark_ms);
3319 }
3320 // Record the number of elements currently on the mark stack, so we
3321 // only iterate over these. (Since evacuation may add to the mark
3322 // stack, doing more exposes race conditions.) If no mark is in
3323 // progress, this will be zero.
3324 _cm->set_oops_do_bound();
3325
3326 if (mark_in_progress())
3327 concurrent_mark()->newCSet();
3328
3329 #if YOUNG_LIST_VERBOSE
3330 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3331 _young_list->print();
3332 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3333 #endif // YOUNG_LIST_VERBOSE
3334
3335 g1_policy()->choose_collection_set(target_pause_time_ms);
3336
3337 // Nothing to do if we were unable to choose a collection set.
3338 #if G1_REM_SET_LOGGING
3339 gclog_or_tty->print_cr("\nAfter pause, heap:");
3340 print();
3341 #endif
3342 PrepareForRSScanningClosure prepare_for_rs_scan;
3343 collection_set_iterate(&prepare_for_rs_scan);
3344
3345 setup_surviving_young_words();
3346
3347 // Set up the gc allocation regions.
3348 get_gc_alloc_regions();
3349
3350 // Actually do the work...
3351 evacuate_collection_set();
3352
3353 free_collection_set(g1_policy()->collection_set());
3354 g1_policy()->clear_collection_set();
3355
3356 cleanup_surviving_young_words();
3357
3358 // Start a new incremental collection set for the next pause.
3359 g1_policy()->start_incremental_cset_building();
3360
3361 // Clear the _cset_fast_test bitmap in anticipation of adding
3362 // regions to the incremental collection set for the next
3363 // evacuation pause.
3364 clear_cset_fast_test();
3365
3366 if (g1_policy()->in_young_gc_mode()) {
3367 _young_list->reset_sampled_info();
3368
3369 // Don't check the whole heap at this point as the
3370 // GC alloc regions from this pause have been tagged
3371 // as survivors and moved on to the survivor list.
3372 // Survivor regions will fail the !is_young() check.
3373 assert(check_young_list_empty(false /* check_heap */),
3374 "young list should be empty");
3375
3376 #if YOUNG_LIST_VERBOSE
3377 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3378 _young_list->print();
3379 #endif // YOUNG_LIST_VERBOSE
3380
3381 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3382 _young_list->first_survivor_region(),
3383 _young_list->last_survivor_region());
3384
3385 _young_list->reset_auxilary_lists();
3386 }
3387
3388 if (evacuation_failed()) {
3389 _summary_bytes_used = recalculate_used();
3390 } else {
3391 // The "used" of the the collection set have already been subtracted
3392 // when they were freed. Add in the bytes evacuated.
3393 _summary_bytes_used += g1_policy()->bytes_in_to_space();
3394 }
3395
3396 if (g1_policy()->in_young_gc_mode() &&
3397 g1_policy()->during_initial_mark_pause()) {
3398 concurrent_mark()->checkpointRootsInitialPost();
3399 set_marking_started();
3400 // CAUTION: after the doConcurrentMark() call below,
3401 // the concurrent marking thread(s) could be running
3402 // concurrently with us. Make sure that anything after
3403 // this point does not assume that we are the only GC thread
3404 // running. Note: of course, the actual marking work will
3405 // not start until the safepoint itself is released in
3406 // ConcurrentGCThread::safepoint_desynchronize().
3407 doConcurrentMark();
3408 }
3409
3410 allocate_dummy_regions();
3411
3412 #if YOUNG_LIST_VERBOSE
3413 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3414 _young_list->print();
3415 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3416 #endif // YOUNG_LIST_VERBOSE
3417
3418 init_mutator_alloc_region();
3419
3420 double end_time_sec = os::elapsedTime();
3421 double pause_time_ms = (end_time_sec - start_time_sec) * MILLIUNITS;
3422 g1_policy()->record_pause_time_ms(pause_time_ms);
3423 g1_policy()->record_collection_pause_end();
3424
3425 MemoryService::track_memory_usage();
3426
3427 if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
3428 HandleMark hm; // Discard invalid handles created during verification
3429 gclog_or_tty->print(" VerifyAfterGC:");
3430 prepare_for_verify();
3431 Universe::verify(false);
3432 }
3433
3434 if (was_enabled) ref_processor()->enable_discovery();
3435
3436 {
3437 size_t expand_bytes = g1_policy()->expansion_amount();
3438 if (expand_bytes > 0) {
3439 size_t bytes_before = capacity();
3440 if (!expand(expand_bytes)) {
3441 // We failed to expand the heap so let's verify that
3442 // committed/uncommitted amount match the backing store
3443 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
3444 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
3445 }
3446 }
3447 }
3448
3449 if (mark_in_progress()) {
3450 concurrent_mark()->update_g1_committed();
3451 }
3452
3453 #ifdef TRACESPINNING
3454 ParallelTaskTerminator::print_termination_counts();
3455 #endif
3456
3457 gc_epilogue(false);
3458 }
3459
3460 if (ExitAfterGCNum > 0 && total_collections() == ExitAfterGCNum) {
3461 gclog_or_tty->print_cr("Stopping after GC #%d", ExitAfterGCNum);
3462 print_tracing_info();
3463 vm_exit(-1);
3464 }
3465 }
3466
3467 verify_region_sets_optional();
3468
3469 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
3470 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3471
3472 if (PrintHeapAtGC) {
3473 Universe::print_heap_after_gc();
3474 }
3475 g1mm()->update_counters();
3476
3477 if (G1SummarizeRSetStats &&
3478 (G1SummarizeRSetStatsPeriod > 0) &&
3479 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3480 g1_rem_set()->print_summary_info();
3481 }
3482
3483 return true;
3484 }
3485
3486 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
3487 {
3488 size_t gclab_word_size;
3489 switch (purpose) {
3490 case GCAllocForSurvived:
3491 gclab_word_size = YoungPLABSize;
3492 break;
3493 case GCAllocForTenured:
3494 gclab_word_size = OldPLABSize;
3495 break;
3496 default:
3497 assert(false, "unknown GCAllocPurpose");
3498 gclab_word_size = OldPLABSize;
3499 break;
3500 }
3501 return gclab_word_size;
3502 }
3503
3504 void G1CollectedHeap::init_mutator_alloc_region() {
3505 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
3506 _mutator_alloc_region.init();
3507 }
3508
3509 void G1CollectedHeap::release_mutator_alloc_region() {
3510 _mutator_alloc_region.release();
3511 assert(_mutator_alloc_region.get() == NULL, "post-condition");
3512 }
3513
3514 void G1CollectedHeap::set_gc_alloc_region(int purpose, HeapRegion* r) {
3515 assert(purpose >= 0 && purpose < GCAllocPurposeCount, "invalid purpose");
3516 // make sure we don't call set_gc_alloc_region() multiple times on
3517 // the same region
3518 assert(r == NULL || !r->is_gc_alloc_region(),
3519 "shouldn't already be a GC alloc region");
3520 assert(r == NULL || !r->isHumongous(),
3521 "humongous regions shouldn't be used as GC alloc regions");
3522
3523 HeapWord* original_top = NULL;
3524 if (r != NULL)
3525 original_top = r->top();
3526
3527 // We will want to record the used space in r as being there before gc.
3528 // One we install it as a GC alloc region it's eligible for allocation.
3529 // So record it now and use it later.
3530 size_t r_used = 0;
3531 if (r != NULL) {
3532 r_used = r->used();
3533
3534 if (G1CollectedHeap::use_parallel_gc_threads()) {
3535 // need to take the lock to guard against two threads calling
3536 // get_gc_alloc_region concurrently (very unlikely but...)
3537 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3538 r->save_marks();
3539 }
3540 }
3541 HeapRegion* old_alloc_region = _gc_alloc_regions[purpose];
3542 _gc_alloc_regions[purpose] = r;
3543 if (old_alloc_region != NULL) {
3544 // Replace aliases too.
3545 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3546 if (_gc_alloc_regions[ap] == old_alloc_region) {
3547 _gc_alloc_regions[ap] = r;
3548 }
3549 }
3550 }
3551 if (r != NULL) {
3552 push_gc_alloc_region(r);
3553 if (mark_in_progress() && original_top != r->next_top_at_mark_start()) {
3554 // We are using a region as a GC alloc region after it has been used
3555 // as a mutator allocation region during the current marking cycle.
3556 // The mutator-allocated objects are currently implicitly marked, but
3557 // when we move hr->next_top_at_mark_start() forward at the the end
3558 // of the GC pause, they won't be. We therefore mark all objects in
3559 // the "gap". We do this object-by-object, since marking densely
3560 // does not currently work right with marking bitmap iteration. This
3561 // means we rely on TLAB filling at the start of pauses, and no
3562 // "resuscitation" of filled TLAB's. If we want to do this, we need
3563 // to fix the marking bitmap iteration.
3564 HeapWord* curhw = r->next_top_at_mark_start();
3565 HeapWord* t = original_top;
3566
3567 while (curhw < t) {
3568 oop cur = (oop)curhw;
3569 // We'll assume parallel for generality. This is rare code.
3570 concurrent_mark()->markAndGrayObjectIfNecessary(cur); // can't we just mark them?
3571 curhw = curhw + cur->size();
3572 }
3573 assert(curhw == t, "Should have parsed correctly.");
3574 }
3575 if (G1PolicyVerbose > 1) {
3576 gclog_or_tty->print("New alloc region ["PTR_FORMAT", "PTR_FORMAT", " PTR_FORMAT") "
3577 "for survivors:", r->bottom(), original_top, r->end());
3578 r->print();
3579 }
3580 g1_policy()->record_before_bytes(r_used);
3581 }
3582 }
3583
3584 void G1CollectedHeap::push_gc_alloc_region(HeapRegion* hr) {
3585 assert(Thread::current()->is_VM_thread() ||
3586 FreeList_lock->owned_by_self(), "Precondition");
3587 assert(!hr->is_gc_alloc_region() && !hr->in_collection_set(),
3588 "Precondition.");
3589 hr->set_is_gc_alloc_region(true);
3590 hr->set_next_gc_alloc_region(_gc_alloc_region_list);
3591 _gc_alloc_region_list = hr;
3592 }
3593
3594 #ifdef G1_DEBUG
3595 class FindGCAllocRegion: public HeapRegionClosure {
3596 public:
3597 bool doHeapRegion(HeapRegion* r) {
3598 if (r->is_gc_alloc_region()) {
3599 gclog_or_tty->print_cr("Region %d ["PTR_FORMAT"...] is still a gc_alloc_region.",
3600 r->hrs_index(), r->bottom());
3601 }
3602 return false;
3603 }
3604 };
3605 #endif // G1_DEBUG
3606
3607 void G1CollectedHeap::forget_alloc_region_list() {
3608 assert_at_safepoint(true /* should_be_vm_thread */);
3609 while (_gc_alloc_region_list != NULL) {
3610 HeapRegion* r = _gc_alloc_region_list;
3611 assert(r->is_gc_alloc_region(), "Invariant.");
3612 // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
3613 // newly allocated data in order to be able to apply deferred updates
3614 // before the GC is done for verification purposes (i.e to allow
3615 // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
3616 // collection.
3617 r->ContiguousSpace::set_saved_mark();
3618 _gc_alloc_region_list = r->next_gc_alloc_region();
3619 r->set_next_gc_alloc_region(NULL);
3620 r->set_is_gc_alloc_region(false);
3621 if (r->is_survivor()) {
3622 if (r->is_empty()) {
3623 r->set_not_young();
3624 } else {
3625 _young_list->add_survivor_region(r);
3626 }
3627 }
3628 }
3629 #ifdef G1_DEBUG
3630 FindGCAllocRegion fa;
3631 heap_region_iterate(&fa);
3632 #endif // G1_DEBUG
3633 }
3634
3635
3636 bool G1CollectedHeap::check_gc_alloc_regions() {
3637 // TODO: allocation regions check
3638 return true;
3639 }
3640
3641 void G1CollectedHeap::get_gc_alloc_regions() {
3642 // First, let's check that the GC alloc region list is empty (it should)
3643 assert(_gc_alloc_region_list == NULL, "invariant");
3644
3645 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3646 assert(_gc_alloc_regions[ap] == NULL, "invariant");
3647 assert(_gc_alloc_region_counts[ap] == 0, "invariant");
3648
3649 // Create new GC alloc regions.
3650 HeapRegion* alloc_region = _retained_gc_alloc_regions[ap];
3651 _retained_gc_alloc_regions[ap] = NULL;
3652
3653 if (alloc_region != NULL) {
3654 assert(_retain_gc_alloc_region[ap], "only way to retain a GC region");
3655
3656 // let's make sure that the GC alloc region is not tagged as such
3657 // outside a GC operation
3658 assert(!alloc_region->is_gc_alloc_region(), "sanity");
3659
3660 if (alloc_region->in_collection_set() ||
3661 alloc_region->top() == alloc_region->end() ||
3662 alloc_region->top() == alloc_region->bottom() ||
3663 alloc_region->isHumongous()) {
3664 // we will discard the current GC alloc region if
3665 // * it's in the collection set (it can happen!),
3666 // * it's already full (no point in using it),
3667 // * it's empty (this means that it was emptied during
3668 // a cleanup and it should be on the free list now), or
3669 // * it's humongous (this means that it was emptied
3670 // during a cleanup and was added to the free list, but
3671 // has been subseqently used to allocate a humongous
3672 // object that may be less than the region size).
3673
3674 alloc_region = NULL;
3675 }
3676 }
3677
3678 if (alloc_region == NULL) {
3679 // we will get a new GC alloc region
3680 alloc_region = new_gc_alloc_region(ap, HeapRegion::GrainWords);
3681 } else {
3682 // the region was retained from the last collection
3683 ++_gc_alloc_region_counts[ap];
3684 if (G1PrintHeapRegions) {
3685 gclog_or_tty->print_cr("new alloc region %d:["PTR_FORMAT", "PTR_FORMAT"], "
3686 "top "PTR_FORMAT,
3687 alloc_region->hrs_index(), alloc_region->bottom(), alloc_region->end(), alloc_region->top());
3688 }
3689 }
3690
3691 if (alloc_region != NULL) {
3692 assert(_gc_alloc_regions[ap] == NULL, "pre-condition");
3693 set_gc_alloc_region(ap, alloc_region);
3694 }
3695
3696 assert(_gc_alloc_regions[ap] == NULL ||
3697 _gc_alloc_regions[ap]->is_gc_alloc_region(),
3698 "the GC alloc region should be tagged as such");
3699 assert(_gc_alloc_regions[ap] == NULL ||
3700 _gc_alloc_regions[ap] == _gc_alloc_region_list,
3701 "the GC alloc region should be the same as the GC alloc list head");
3702 }
3703 // Set alternative regions for allocation purposes that have reached
3704 // their limit.
3705 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3706 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(ap);
3707 if (_gc_alloc_regions[ap] == NULL && alt_purpose != ap) {
3708 _gc_alloc_regions[ap] = _gc_alloc_regions[alt_purpose];
3709 }
3710 }
3711 assert(check_gc_alloc_regions(), "alloc regions messed up");
3712 }
3713
3714 void G1CollectedHeap::release_gc_alloc_regions(bool totally) {
3715 // We keep a separate list of all regions that have been alloc regions in
3716 // the current collection pause. Forget that now. This method will
3717 // untag the GC alloc regions and tear down the GC alloc region
3718 // list. It's desirable that no regions are tagged as GC alloc
3719 // outside GCs.
3720
3721 forget_alloc_region_list();
3722
3723 // The current alloc regions contain objs that have survived
3724 // collection. Make them no longer GC alloc regions.
3725 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3726 HeapRegion* r = _gc_alloc_regions[ap];
3727 _retained_gc_alloc_regions[ap] = NULL;
3728 _gc_alloc_region_counts[ap] = 0;
3729
3730 if (r != NULL) {
3731 // we retain nothing on _gc_alloc_regions between GCs
3732 set_gc_alloc_region(ap, NULL);
3733
3734 if (r->is_empty()) {
3735 // We didn't actually allocate anything in it; let's just put
3736 // it back on the free list.
3737 _free_list.add_as_head(r);
3738 } else if (_retain_gc_alloc_region[ap] && !totally) {
3739 // retain it so that we can use it at the beginning of the next GC
3740 _retained_gc_alloc_regions[ap] = r;
3741 }
3742 }
3743 }
3744 }
3745
3746 #ifndef PRODUCT
3747 // Useful for debugging
3748
3749 void G1CollectedHeap::print_gc_alloc_regions() {
3750 gclog_or_tty->print_cr("GC alloc regions");
3751 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
3752 HeapRegion* r = _gc_alloc_regions[ap];
3753 if (r == NULL) {
3754 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT, ap, NULL);
3755 } else {
3756 gclog_or_tty->print_cr(" %2d : "PTR_FORMAT" "SIZE_FORMAT,
3757 ap, r->bottom(), r->used());
3758 }
3759 }
3760 }
3761 #endif // PRODUCT
3762
3763 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
3764 _drain_in_progress = false;
3765 set_evac_failure_closure(cl);
3766 _evac_failure_scan_stack = new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
3767 }
3768
3769 void G1CollectedHeap::finalize_for_evac_failure() {
3770 assert(_evac_failure_scan_stack != NULL &&
3771 _evac_failure_scan_stack->length() == 0,
3772 "Postcondition");
3773 assert(!_drain_in_progress, "Postcondition");
3774 delete _evac_failure_scan_stack;
3775 _evac_failure_scan_stack = NULL;
3776 }
3777
3778
3779
3780 // *** Sequential G1 Evacuation
3781
3782 class G1IsAliveClosure: public BoolObjectClosure {
3783 G1CollectedHeap* _g1;
3784 public:
3785 G1IsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3786 void do_object(oop p) { assert(false, "Do not call."); }
3787 bool do_object_b(oop p) {
3788 // It is reachable if it is outside the collection set, or is inside
3789 // and forwarded.
3790
3791 #ifdef G1_DEBUG
3792 gclog_or_tty->print_cr("is alive "PTR_FORMAT" in CS %d forwarded %d overall %d",
3793 (void*) p, _g1->obj_in_cs(p), p->is_forwarded(),
3794 !_g1->obj_in_cs(p) || p->is_forwarded());
3795 #endif // G1_DEBUG
3796
3797 return !_g1->obj_in_cs(p) || p->is_forwarded();
3798 }
3799 };
3800
3801 class G1KeepAliveClosure: public OopClosure {
3802 G1CollectedHeap* _g1;
3803 public:
3804 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
3805 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3806 void do_oop( oop* p) {
3807 oop obj = *p;
3808 #ifdef G1_DEBUG
3809 if (PrintGC && Verbose) {
3810 gclog_or_tty->print_cr("keep alive *"PTR_FORMAT" = "PTR_FORMAT" "PTR_FORMAT,
3811 p, (void*) obj, (void*) *p);
3812 }
3813 #endif // G1_DEBUG
3814
3815 if (_g1->obj_in_cs(obj)) {
3816 assert( obj->is_forwarded(), "invariant" );
3817 *p = obj->forwardee();
3818 #ifdef G1_DEBUG
3819 gclog_or_tty->print_cr(" in CSet: moved "PTR_FORMAT" -> "PTR_FORMAT,
3820 (void*) obj, (void*) *p);
3821 #endif // G1_DEBUG
3822 }
3823 }
3824 };
3825
3826 class UpdateRSetDeferred : public OopsInHeapRegionClosure {
3827 private:
3828 G1CollectedHeap* _g1;
3829 DirtyCardQueue *_dcq;
3830 CardTableModRefBS* _ct_bs;
3831
3832 public:
3833 UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
3834 _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}
3835
3836 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3837 virtual void do_oop( oop* p) { do_oop_work(p); }
3838 template <class T> void do_oop_work(T* p) {
3839 assert(_from->is_in_reserved(p), "paranoia");
3840 if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
3841 !_from->is_survivor()) {
3842 size_t card_index = _ct_bs->index_for(p);
3843 if (_ct_bs->mark_card_deferred(card_index)) {
3844 _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
3845 }
3846 }
3847 }
3848 };
3849
3850 class RemoveSelfPointerClosure: public ObjectClosure {
3851 private:
3852 G1CollectedHeap* _g1;
3853 ConcurrentMark* _cm;
3854 HeapRegion* _hr;
3855 size_t _prev_marked_bytes;
3856 size_t _next_marked_bytes;
3857 OopsInHeapRegionClosure *_cl;
3858 public:
3859 RemoveSelfPointerClosure(G1CollectedHeap* g1, HeapRegion* hr,
3860 OopsInHeapRegionClosure* cl) :
3861 _g1(g1), _hr(hr), _cm(_g1->concurrent_mark()), _prev_marked_bytes(0),
3862 _next_marked_bytes(0), _cl(cl) {}
3863
3864 size_t prev_marked_bytes() { return _prev_marked_bytes; }
3865 size_t next_marked_bytes() { return _next_marked_bytes; }
3866
3867 // <original comment>
3868 // The original idea here was to coalesce evacuated and dead objects.
3869 // However that caused complications with the block offset table (BOT).
3870 // In particular if there were two TLABs, one of them partially refined.
3871 // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
3872 // The BOT entries of the unrefined part of TLAB_2 point to the start
3873 // of TLAB_2. If the last object of the TLAB_1 and the first object
3874 // of TLAB_2 are coalesced, then the cards of the unrefined part
3875 // would point into middle of the filler object.
3876 // The current approach is to not coalesce and leave the BOT contents intact.
3877 // </original comment>
3878 //
3879 // We now reset the BOT when we start the object iteration over the
3880 // region and refine its entries for every object we come across. So
3881 // the above comment is not really relevant and we should be able
3882 // to coalesce dead objects if we want to.
3883 void do_object(oop obj) {
3884 HeapWord* obj_addr = (HeapWord*) obj;
3885 assert(_hr->is_in(obj_addr), "sanity");
3886 size_t obj_size = obj->size();
3887 _hr->update_bot_for_object(obj_addr, obj_size);
3888 if (obj->is_forwarded() && obj->forwardee() == obj) {
3889 // The object failed to move.
3890 assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");
3891 _cm->markPrev(obj);
3892 assert(_cm->isPrevMarked(obj), "Should be marked!");
3893 _prev_marked_bytes += (obj_size * HeapWordSize);
3894 if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {
3895 _cm->markAndGrayObjectIfNecessary(obj);
3896 }
3897 obj->set_mark(markOopDesc::prototype());
3898 // While we were processing RSet buffers during the
3899 // collection, we actually didn't scan any cards on the
3900 // collection set, since we didn't want to update remebered
3901 // sets with entries that point into the collection set, given
3902 // that live objects fromthe collection set are about to move
3903 // and such entries will be stale very soon. This change also
3904 // dealt with a reliability issue which involved scanning a
3905 // card in the collection set and coming across an array that
3906 // was being chunked and looking malformed. The problem is
3907 // that, if evacuation fails, we might have remembered set
3908 // entries missing given that we skipped cards on the
3909 // collection set. So, we'll recreate such entries now.
3910 obj->oop_iterate(_cl);
3911 assert(_cm->isPrevMarked(obj), "Should be marked!");
3912 } else {
3913 // The object has been either evacuated or is dead. Fill it with a
3914 // dummy object.
3915 MemRegion mr((HeapWord*)obj, obj_size);
3916 CollectedHeap::fill_with_object(mr);
3917 _cm->clearRangeBothMaps(mr);
3918 }
3919 }
3920 };
3921
3922 void G1CollectedHeap::remove_self_forwarding_pointers() {
3923 UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
3924 DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
3925 UpdateRSetDeferred deferred_update(_g1h, &dcq);
3926 OopsInHeapRegionClosure *cl;
3927 if (G1DeferredRSUpdate) {
3928 cl = &deferred_update;
3929 } else {
3930 cl = &immediate_update;
3931 }
3932 HeapRegion* cur = g1_policy()->collection_set();
3933 while (cur != NULL) {
3934 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3935 assert(!cur->isHumongous(), "sanity");
3936
3937 if (cur->evacuation_failed()) {
3938 assert(cur->in_collection_set(), "bad CS");
3939 RemoveSelfPointerClosure rspc(_g1h, cur, cl);
3940
3941 cur->reset_bot();
3942 cl->set_region(cur);
3943 cur->object_iterate(&rspc);
3944
3945 // A number of manipulations to make the TAMS be the current top,
3946 // and the marked bytes be the ones observed in the iteration.
3947 if (_g1h->concurrent_mark()->at_least_one_mark_complete()) {
3948 // The comments below are the postconditions achieved by the
3949 // calls. Note especially the last such condition, which says that
3950 // the count of marked bytes has been properly restored.
3951 cur->note_start_of_marking(false);
3952 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3953 cur->add_to_marked_bytes(rspc.prev_marked_bytes());
3954 // _next_marked_bytes == prev_marked_bytes.
3955 cur->note_end_of_marking();
3956 // _prev_top_at_mark_start == top(),
3957 // _prev_marked_bytes == prev_marked_bytes
3958 }
3959 // If there is no mark in progress, we modified the _next variables
3960 // above needlessly, but harmlessly.
3961 if (_g1h->mark_in_progress()) {
3962 cur->note_start_of_marking(false);
3963 // _next_top_at_mark_start == top, _next_marked_bytes == 0
3964 // _next_marked_bytes == next_marked_bytes.
3965 }
3966
3967 // Now make sure the region has the right index in the sorted array.
3968 g1_policy()->note_change_in_marked_bytes(cur);
3969 }
3970 cur = cur->next_in_collection_set();
3971 }
3972 assert(g1_policy()->assertMarkedBytesDataOK(), "Should be!");
3973
3974 // Now restore saved marks, if any.
3975 if (_objs_with_preserved_marks != NULL) {
3976 assert(_preserved_marks_of_objs != NULL, "Both or none.");
3977 guarantee(_objs_with_preserved_marks->length() ==
3978 _preserved_marks_of_objs->length(), "Both or none.");
3979 for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
3980 oop obj = _objs_with_preserved_marks->at(i);
3981 markOop m = _preserved_marks_of_objs->at(i);
3982 obj->set_mark(m);
3983 }
3984 // Delete the preserved marks growable arrays (allocated on the C heap).
3985 delete _objs_with_preserved_marks;
3986 delete _preserved_marks_of_objs;
3987 _objs_with_preserved_marks = NULL;
3988 _preserved_marks_of_objs = NULL;
3989 }
3990 }
3991
3992 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
3993 _evac_failure_scan_stack->push(obj);
3994 }
3995
3996 void G1CollectedHeap::drain_evac_failure_scan_stack() {
3997 assert(_evac_failure_scan_stack != NULL, "precondition");
3998
3999 while (_evac_failure_scan_stack->length() > 0) {
4000 oop obj = _evac_failure_scan_stack->pop();
4001 _evac_failure_closure->set_region(heap_region_containing(obj));
4002 obj->oop_iterate_backwards(_evac_failure_closure);
4003 }
4004 }
4005
4006 oop
4007 G1CollectedHeap::handle_evacuation_failure_par(OopsInHeapRegionClosure* cl,
4008 oop old) {
4009 assert(obj_in_cs(old),
4010 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4011 (HeapWord*) old));
4012 markOop m = old->mark();
4013 oop forward_ptr = old->forward_to_atomic(old);
4014 if (forward_ptr == NULL) {
4015 // Forward-to-self succeeded.
4016 if (_evac_failure_closure != cl) {
4017 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4018 assert(!_drain_in_progress,
4019 "Should only be true while someone holds the lock.");
4020 // Set the global evac-failure closure to the current thread's.
4021 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4022 set_evac_failure_closure(cl);
4023 // Now do the common part.
4024 handle_evacuation_failure_common(old, m);
4025 // Reset to NULL.
4026 set_evac_failure_closure(NULL);
4027 } else {
4028 // The lock is already held, and this is recursive.
4029 assert(_drain_in_progress, "This should only be the recursive case.");
4030 handle_evacuation_failure_common(old, m);
4031 }
4032 return old;
4033 } else {
4034 // Forward-to-self failed. Either someone else managed to allocate
4035 // space for this object (old != forward_ptr) or they beat us in
4036 // self-forwarding it (old == forward_ptr).
4037 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4038 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4039 "should not be in the CSet",
4040 (HeapWord*) old, (HeapWord*) forward_ptr));
4041 return forward_ptr;
4042 }
4043 }
4044
4045 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4046 set_evacuation_failed(true);
4047
4048 preserve_mark_if_necessary(old, m);
4049
4050 HeapRegion* r = heap_region_containing(old);
4051 if (!r->evacuation_failed()) {
4052 r->set_evacuation_failed(true);
4053 if (G1PrintHeapRegions) {
4054 gclog_or_tty->print("overflow in heap region "PTR_FORMAT" "
4055 "["PTR_FORMAT","PTR_FORMAT")\n",
4056 r, r->bottom(), r->end());
4057 }
4058 }
4059
4060 push_on_evac_failure_scan_stack(old);
4061
4062 if (!_drain_in_progress) {
4063 // prevent recursion in copy_to_survivor_space()
4064 _drain_in_progress = true;
4065 drain_evac_failure_scan_stack();
4066 _drain_in_progress = false;
4067 }
4068 }
4069
4070 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4071 assert(evacuation_failed(), "Oversaving!");
4072 // We want to call the "for_promotion_failure" version only in the
4073 // case of a promotion failure.
4074 if (m->must_be_preserved_for_promotion_failure(obj)) {
4075 if (_objs_with_preserved_marks == NULL) {
4076 assert(_preserved_marks_of_objs == NULL, "Both or none.");
4077 _objs_with_preserved_marks =
4078 new (ResourceObj::C_HEAP) GrowableArray<oop>(40, true);
4079 _preserved_marks_of_objs =
4080 new (ResourceObj::C_HEAP) GrowableArray<markOop>(40, true);
4081 }
4082 _objs_with_preserved_marks->push(obj);
4083 _preserved_marks_of_objs->push(m);
4084 }
4085 }
4086
4087 // *** Parallel G1 Evacuation
4088
4089 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4090 size_t word_size) {
4091 assert(!isHumongous(word_size),
4092 err_msg("we should not be seeing humongous allocation requests "
4093 "during GC, word_size = "SIZE_FORMAT, word_size));
4094
4095 HeapRegion* alloc_region = _gc_alloc_regions[purpose];
4096 // let the caller handle alloc failure
4097 if (alloc_region == NULL) return NULL;
4098
4099 HeapWord* block = alloc_region->par_allocate(word_size);
4100 if (block == NULL) {
4101 block = allocate_during_gc_slow(purpose, alloc_region, true, word_size);
4102 }
4103 return block;
4104 }
4105
4106 void G1CollectedHeap::retire_alloc_region(HeapRegion* alloc_region,
4107 bool par) {
4108 // Another thread might have obtained alloc_region for the given
4109 // purpose, and might be attempting to allocate in it, and might
4110 // succeed. Therefore, we can't do the "finalization" stuff on the
4111 // region below until we're sure the last allocation has happened.
4112 // We ensure this by allocating the remaining space with a garbage
4113 // object.
4114 if (par) par_allocate_remaining_space(alloc_region);
4115 // Now we can do the post-GC stuff on the region.
4116 alloc_region->note_end_of_copying();
4117 g1_policy()->record_after_bytes(alloc_region->used());
4118 }
4119
4120 HeapWord*
4121 G1CollectedHeap::allocate_during_gc_slow(GCAllocPurpose purpose,
4122 HeapRegion* alloc_region,
4123 bool par,
4124 size_t word_size) {
4125 assert(!isHumongous(word_size),
4126 err_msg("we should not be seeing humongous allocation requests "
4127 "during GC, word_size = "SIZE_FORMAT, word_size));
4128
4129 // We need to make sure we serialize calls to this method. Given
4130 // that the FreeList_lock guards accesses to the free_list anyway,
4131 // and we need to potentially remove a region from it, we'll use it
4132 // to protect the whole call.
4133 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4134
4135 HeapWord* block = NULL;
4136 // In the parallel case, a previous thread to obtain the lock may have
4137 // already assigned a new gc_alloc_region.
4138 if (alloc_region != _gc_alloc_regions[purpose]) {
4139 assert(par, "But should only happen in parallel case.");
4140 alloc_region = _gc_alloc_regions[purpose];
4141 if (alloc_region == NULL) return NULL;
4142 block = alloc_region->par_allocate(word_size);
4143 if (block != NULL) return block;
4144 // Otherwise, continue; this new region is empty, too.
4145 }
4146 assert(alloc_region != NULL, "We better have an allocation region");
4147 retire_alloc_region(alloc_region, par);
4148
4149 if (_gc_alloc_region_counts[purpose] >= g1_policy()->max_regions(purpose)) {
4150 // Cannot allocate more regions for the given purpose.
4151 GCAllocPurpose alt_purpose = g1_policy()->alternative_purpose(purpose);
4152 // Is there an alternative?
4153 if (purpose != alt_purpose) {
4154 HeapRegion* alt_region = _gc_alloc_regions[alt_purpose];
4155 // Has not the alternative region been aliased?
4156 if (alloc_region != alt_region && alt_region != NULL) {
4157 // Try to allocate in the alternative region.
4158 if (par) {
4159 block = alt_region->par_allocate(word_size);
4160 } else {
4161 block = alt_region->allocate(word_size);
4162 }
4163 // Make an alias.
4164 _gc_alloc_regions[purpose] = _gc_alloc_regions[alt_purpose];
4165 if (block != NULL) {
4166 return block;
4167 }
4168 retire_alloc_region(alt_region, par);
4169 }
4170 // Both the allocation region and the alternative one are full
4171 // and aliased, replace them with a new allocation region.
4172 purpose = alt_purpose;
4173 } else {
4174 set_gc_alloc_region(purpose, NULL);
4175 return NULL;
4176 }
4177 }
4178
4179 // Now allocate a new region for allocation.
4180 alloc_region = new_gc_alloc_region(purpose, word_size);
4181
4182 // let the caller handle alloc failure
4183 if (alloc_region != NULL) {
4184
4185 assert(check_gc_alloc_regions(), "alloc regions messed up");
4186 assert(alloc_region->saved_mark_at_top(),
4187 "Mark should have been saved already.");
4188 // This must be done last: once it's installed, other regions may
4189 // allocate in it (without holding the lock.)
4190 set_gc_alloc_region(purpose, alloc_region);
4191
4192 if (par) {
4193 block = alloc_region->par_allocate(word_size);
4194 } else {
4195 block = alloc_region->allocate(word_size);
4196 }
4197 // Caller handles alloc failure.
4198 } else {
4199 // This sets other apis using the same old alloc region to NULL, also.
4200 set_gc_alloc_region(purpose, NULL);
4201 }
4202 return block; // May be NULL.
4203 }
4204
4205 void G1CollectedHeap::par_allocate_remaining_space(HeapRegion* r) {
4206 HeapWord* block = NULL;
4207 size_t free_words;
4208 do {
4209 free_words = r->free()/HeapWordSize;
4210 // If there's too little space, no one can allocate, so we're done.
4211 if (free_words < CollectedHeap::min_fill_size()) return;
4212 // Otherwise, try to claim it.
4213 block = r->par_allocate(free_words);
4214 } while (block == NULL);
4215 fill_with_object(block, free_words);
4216 }
4217
4218 #ifndef PRODUCT
4219 bool GCLabBitMapClosure::do_bit(size_t offset) {
4220 HeapWord* addr = _bitmap->offsetToHeapWord(offset);
4221 guarantee(_cm->isMarked(oop(addr)), "it should be!");
4222 return true;
4223 }
4224 #endif // PRODUCT
4225
4226 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
4227 : _g1h(g1h),
4228 _refs(g1h->task_queue(queue_num)),
4229 _dcq(&g1h->dirty_card_queue_set()),
4230 _ct_bs((CardTableModRefBS*)_g1h->barrier_set()),
4231 _g1_rem(g1h->g1_rem_set()),
4232 _hash_seed(17), _queue_num(queue_num),
4233 _term_attempts(0),
4234 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4235 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4236 _age_table(false),
4237 _strong_roots_time(0), _term_time(0),
4238 _alloc_buffer_waste(0), _undo_waste(0)
4239 {
4240 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4241 // we "sacrifice" entry 0 to keep track of surviving bytes for
4242 // non-young regions (where the age is -1)
4243 // We also add a few elements at the beginning and at the end in
4244 // an attempt to eliminate cache contention
4245 size_t real_length = 1 + _g1h->g1_policy()->young_cset_length();
4246 size_t array_length = PADDING_ELEM_NUM +
4247 real_length +
4248 PADDING_ELEM_NUM;
4249 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length);
4250 if (_surviving_young_words_base == NULL)
4251 vm_exit_out_of_memory(array_length * sizeof(size_t),
4252 "Not enough space for young surv histo.");
4253 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4254 memset(_surviving_young_words, 0, real_length * sizeof(size_t));
4255
4256 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4257 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4258
4259 _start = os::elapsedTime();
4260 }
4261
4262 void
4263 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4264 {
4265 st->print_raw_cr("GC Termination Stats");
4266 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4267 " ------waste (KiB)------");
4268 st->print_raw_cr("thr ms ms % ms % attempts"
4269 " total alloc undo");
4270 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4271 " ------- ------- -------");
4272 }
4273
4274 void
4275 G1ParScanThreadState::print_termination_stats(int i,
4276 outputStream* const st) const
4277 {
4278 const double elapsed_ms = elapsed_time() * 1000.0;
4279 const double s_roots_ms = strong_roots_time() * 1000.0;
4280 const double term_ms = term_time() * 1000.0;
4281 st->print_cr("%3d %9.2f %9.2f %6.2f "
4282 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4283 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4284 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4285 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4286 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4287 alloc_buffer_waste() * HeapWordSize / K,
4288 undo_waste() * HeapWordSize / K);
4289 }
4290
4291 #ifdef ASSERT
4292 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4293 assert(ref != NULL, "invariant");
4294 assert(UseCompressedOops, "sanity");
4295 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4296 oop p = oopDesc::load_decode_heap_oop(ref);
4297 assert(_g1h->is_in_g1_reserved(p),
4298 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4299 return true;
4300 }
4301
4302 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4303 assert(ref != NULL, "invariant");
4304 if (has_partial_array_mask(ref)) {
4305 // Must be in the collection set--it's already been copied.
4306 oop p = clear_partial_array_mask(ref);
4307 assert(_g1h->obj_in_cs(p),
4308 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4309 } else {
4310 oop p = oopDesc::load_decode_heap_oop(ref);
4311 assert(_g1h->is_in_g1_reserved(p),
4312 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, intptr_t(p)));
4313 }
4314 return true;
4315 }
4316
4317 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4318 if (ref.is_narrow()) {
4319 return verify_ref((narrowOop*) ref);
4320 } else {
4321 return verify_ref((oop*) ref);
4322 }
4323 }
4324 #endif // ASSERT
4325
4326 void G1ParScanThreadState::trim_queue() {
4327 StarTask ref;
4328 do {
4329 // Drain the overflow stack first, so other threads can steal.
4330 while (refs()->pop_overflow(ref)) {
4331 deal_with_reference(ref);
4332 }
4333 while (refs()->pop_local(ref)) {
4334 deal_with_reference(ref);
4335 }
4336 } while (!refs()->is_empty());
4337 }
4338
4339 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1, G1ParScanThreadState* par_scan_state) :
4340 _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
4341 _par_scan_state(par_scan_state) { }
4342
4343 template <class T> void G1ParCopyHelper::mark_forwardee(T* p) {
4344 // This is called _after_ do_oop_work has been called, hence after
4345 // the object has been relocated to its new location and *p points
4346 // to its new location.
4347
4348 T heap_oop = oopDesc::load_heap_oop(p);
4349 if (!oopDesc::is_null(heap_oop)) {
4350 oop obj = oopDesc::decode_heap_oop(heap_oop);
4351 HeapWord* addr = (HeapWord*)obj;
4352 if (_g1->is_in_g1_reserved(addr)) {
4353 _cm->grayRoot(oop(addr));
4354 }
4355 }
4356 }
4357
4358 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
4359 size_t word_sz = old->size();
4360 HeapRegion* from_region = _g1->heap_region_containing_raw(old);
4361 // +1 to make the -1 indexes valid...
4362 int young_index = from_region->young_index_in_cset()+1;
4363 assert( (from_region->is_young() && young_index > 0) ||
4364 (!from_region->is_young() && young_index == 0), "invariant" );
4365 G1CollectorPolicy* g1p = _g1->g1_policy();
4366 markOop m = old->mark();
4367 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4368 : m->age();
4369 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4370 word_sz);
4371 HeapWord* obj_ptr = _par_scan_state->allocate(alloc_purpose, word_sz);
4372 oop obj = oop(obj_ptr);
4373
4374 if (obj_ptr == NULL) {
4375 // This will either forward-to-self, or detect that someone else has
4376 // installed a forwarding pointer.
4377 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4378 return _g1->handle_evacuation_failure_par(cl, old);
4379 }
4380
4381 // We're going to allocate linearly, so might as well prefetch ahead.
4382 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4383
4384 oop forward_ptr = old->forward_to_atomic(obj);
4385 if (forward_ptr == NULL) {
4386 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4387 if (g1p->track_object_age(alloc_purpose)) {
4388 // We could simply do obj->incr_age(). However, this causes a
4389 // performance issue. obj->incr_age() will first check whether
4390 // the object has a displaced mark by checking its mark word;
4391 // getting the mark word from the new location of the object
4392 // stalls. So, given that we already have the mark word and we
4393 // are about to install it anyway, it's better to increase the
4394 // age on the mark word, when the object does not have a
4395 // displaced mark word. We're not expecting many objects to have
4396 // a displaced marked word, so that case is not optimized
4397 // further (it could be...) and we simply call obj->incr_age().
4398
4399 if (m->has_displaced_mark_helper()) {
4400 // in this case, we have to install the mark word first,
4401 // otherwise obj looks to be forwarded (the old mark word,
4402 // which contains the forward pointer, was copied)
4403 obj->set_mark(m);
4404 obj->incr_age();
4405 } else {
4406 m = m->incr_age();
4407 obj->set_mark(m);
4408 }
4409 _par_scan_state->age_table()->add(obj, word_sz);
4410 } else {
4411 obj->set_mark(m);
4412 }
4413
4414 // preserve "next" mark bit
4415 if (_g1->mark_in_progress() && !_g1->is_obj_ill(old)) {
4416 if (!use_local_bitmaps ||
4417 !_par_scan_state->alloc_buffer(alloc_purpose)->mark(obj_ptr)) {
4418 // if we couldn't mark it on the local bitmap (this happens when
4419 // the object was not allocated in the GCLab), we have to bite
4420 // the bullet and do the standard parallel mark
4421 _cm->markAndGrayObjectIfNecessary(obj);
4422 }
4423 #if 1
4424 if (_g1->isMarkedNext(old)) {
4425 _cm->nextMarkBitMap()->parClear((HeapWord*)old);
4426 }
4427 #endif
4428 }
4429
4430 size_t* surv_young_words = _par_scan_state->surviving_young_words();
4431 surv_young_words[young_index] += word_sz;
4432
4433 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4434 arrayOop(old)->set_length(0);
4435 oop* old_p = set_partial_array_mask(old);
4436 _par_scan_state->push_on_queue(old_p);
4437 } else {
4438 // No point in using the slower heap_region_containing() method,
4439 // given that we know obj is in the heap.
4440 _scanner->set_region(_g1->heap_region_containing_raw(obj));
4441 obj->oop_iterate_backwards(_scanner);
4442 }
4443 } else {
4444 _par_scan_state->undo_allocation(alloc_purpose, obj_ptr, word_sz);
4445 obj = forward_ptr;
4446 }
4447 return obj;
4448 }
4449
4450 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_forwardee>
4451 template <class T>
4452 void G1ParCopyClosure <do_gen_barrier, barrier, do_mark_forwardee>
4453 ::do_oop_work(T* p) {
4454 oop obj = oopDesc::load_decode_heap_oop(p);
4455 assert(barrier != G1BarrierRS || obj != NULL,
4456 "Precondition: G1BarrierRS implies obj is nonNull");
4457
4458 // here the null check is implicit in the cset_fast_test() test
4459 if (_g1->in_cset_fast_test(obj)) {
4460 #if G1_REM_SET_LOGGING
4461 gclog_or_tty->print_cr("Loc "PTR_FORMAT" contains pointer "PTR_FORMAT" "
4462 "into CS.", p, (void*) obj);
4463 #endif
4464 if (obj->is_forwarded()) {
4465 oopDesc::encode_store_heap_oop(p, obj->forwardee());
4466 } else {
4467 oop copy_oop = copy_to_survivor_space(obj);
4468 oopDesc::encode_store_heap_oop(p, copy_oop);
4469 }
4470 // When scanning the RS, we only care about objs in CS.
4471 if (barrier == G1BarrierRS) {
4472 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4473 }
4474 }
4475
4476 if (barrier == G1BarrierEvac && obj != NULL) {
4477 _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
4478 }
4479
4480 if (do_gen_barrier && obj != NULL) {
4481 par_do_barrier(p);
4482 }
4483 }
4484
4485 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(oop* p);
4486 template void G1ParCopyClosure<false, G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4487
4488 template <class T> void G1ParScanPartialArrayClosure::do_oop_nv(T* p) {
4489 assert(has_partial_array_mask(p), "invariant");
4490 oop old = clear_partial_array_mask(p);
4491 assert(old->is_objArray(), "must be obj array");
4492 assert(old->is_forwarded(), "must be forwarded");
4493 assert(Universe::heap()->is_in_reserved(old), "must be in heap.");
4494
4495 objArrayOop obj = objArrayOop(old->forwardee());
4496 assert((void*)old != (void*)old->forwardee(), "self forwarding here?");
4497 // Process ParGCArrayScanChunk elements now
4498 // and push the remainder back onto queue
4499 int start = arrayOop(old)->length();
4500 int end = obj->length();
4501 int remainder = end - start;
4502 assert(start <= end, "just checking");
4503 if (remainder > 2 * ParGCArrayScanChunk) {
4504 // Test above combines last partial chunk with a full chunk
4505 end = start + ParGCArrayScanChunk;
4506 arrayOop(old)->set_length(end);
4507 // Push remainder.
4508 oop* old_p = set_partial_array_mask(old);
4509 assert(arrayOop(old)->length() < obj->length(), "Empty push?");
4510 _par_scan_state->push_on_queue(old_p);
4511 } else {
4512 // Restore length so that the heap remains parsable in
4513 // case of evacuation failure.
4514 arrayOop(old)->set_length(end);
4515 }
4516 _scanner.set_region(_g1->heap_region_containing_raw(obj));
4517 // process our set of indices (include header in first chunk)
4518 obj->oop_iterate_range(&_scanner, start, end);
4519 }
4520
4521 class G1ParEvacuateFollowersClosure : public VoidClosure {
4522 protected:
4523 G1CollectedHeap* _g1h;
4524 G1ParScanThreadState* _par_scan_state;
4525 RefToScanQueueSet* _queues;
4526 ParallelTaskTerminator* _terminator;
4527
4528 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4529 RefToScanQueueSet* queues() { return _queues; }
4530 ParallelTaskTerminator* terminator() { return _terminator; }
4531
4532 public:
4533 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4534 G1ParScanThreadState* par_scan_state,
4535 RefToScanQueueSet* queues,
4536 ParallelTaskTerminator* terminator)
4537 : _g1h(g1h), _par_scan_state(par_scan_state),
4538 _queues(queues), _terminator(terminator) {}
4539
4540 void do_void();
4541
4542 private:
4543 inline bool offer_termination();
4544 };
4545
4546 bool G1ParEvacuateFollowersClosure::offer_termination() {
4547 G1ParScanThreadState* const pss = par_scan_state();
4548 pss->start_term_time();
4549 const bool res = terminator()->offer_termination();
4550 pss->end_term_time();
4551 return res;
4552 }
4553
4554 void G1ParEvacuateFollowersClosure::do_void() {
4555 StarTask stolen_task;
4556 G1ParScanThreadState* const pss = par_scan_state();
4557 pss->trim_queue();
4558
4559 do {
4560 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4561 assert(pss->verify_task(stolen_task), "sanity");
4562 if (stolen_task.is_narrow()) {
4563 pss->deal_with_reference((narrowOop*) stolen_task);
4564 } else {
4565 pss->deal_with_reference((oop*) stolen_task);
4566 }
4567
4568 // We've just processed a reference and we might have made
4569 // available new entries on the queues. So we have to make sure
4570 // we drain the queues as necessary.
4571 pss->trim_queue();
4572 }
4573 } while (!offer_termination());
4574
4575 pss->retire_alloc_buffers();
4576 }
4577
4578 class G1ParTask : public AbstractGangTask {
4579 protected:
4580 G1CollectedHeap* _g1h;
4581 RefToScanQueueSet *_queues;
4582 ParallelTaskTerminator _terminator;
4583 int _n_workers;
4584
4585 Mutex _stats_lock;
4586 Mutex* stats_lock() { return &_stats_lock; }
4587
4588 size_t getNCards() {
4589 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4590 / G1BlockOffsetSharedArray::N_bytes;
4591 }
4592
4593 public:
4594 G1ParTask(G1CollectedHeap* g1h, int workers, RefToScanQueueSet *task_queues)
4595 : AbstractGangTask("G1 collection"),
4596 _g1h(g1h),
4597 _queues(task_queues),
4598 _terminator(workers, _queues),
4599 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true),
4600 _n_workers(workers)
4601 {}
4602
4603 RefToScanQueueSet* queues() { return _queues; }
4604
4605 RefToScanQueue *work_queue(int i) {
4606 return queues()->queue(i);
4607 }
4608
4609 void work(int i) {
4610 if (i >= _n_workers) return; // no work needed this round
4611
4612 double start_time_ms = os::elapsedTime() * 1000.0;
4613 _g1h->g1_policy()->record_gc_worker_start_time(i, start_time_ms);
4614
4615 ResourceMark rm;
4616 HandleMark hm;
4617
4618 G1ParScanThreadState pss(_g1h, i);
4619 G1ParScanHeapEvacClosure scan_evac_cl(_g1h, &pss);
4620 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss);
4621 G1ParScanPartialArrayClosure partial_scan_cl(_g1h, &pss);
4622
4623 pss.set_evac_closure(&scan_evac_cl);
4624 pss.set_evac_failure_closure(&evac_failure_cl);
4625 pss.set_partial_scan_closure(&partial_scan_cl);
4626
4627 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss);
4628 G1ParScanPermClosure only_scan_perm_cl(_g1h, &pss);
4629 G1ParScanHeapRSClosure only_scan_heap_rs_cl(_g1h, &pss);
4630 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4631
4632 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss);
4633 G1ParScanAndMarkPermClosure scan_mark_perm_cl(_g1h, &pss);
4634 G1ParScanAndMarkHeapRSClosure scan_mark_heap_rs_cl(_g1h, &pss);
4635
4636 OopsInHeapRegionClosure *scan_root_cl;
4637 OopsInHeapRegionClosure *scan_perm_cl;
4638
4639 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4640 scan_root_cl = &scan_mark_root_cl;
4641 scan_perm_cl = &scan_mark_perm_cl;
4642 } else {
4643 scan_root_cl = &only_scan_root_cl;
4644 scan_perm_cl = &only_scan_perm_cl;
4645 }
4646
4647 pss.start_strong_roots();
4648 _g1h->g1_process_strong_roots(/* not collecting perm */ false,
4649 SharedHeap::SO_AllClasses,
4650 scan_root_cl,
4651 &push_heap_rs_cl,
4652 scan_perm_cl,
4653 i);
4654 pss.end_strong_roots();
4655 {
4656 double start = os::elapsedTime();
4657 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4658 evac.do_void();
4659 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4660 double term_ms = pss.term_time()*1000.0;
4661 _g1h->g1_policy()->record_obj_copy_time(i, elapsed_ms-term_ms);
4662 _g1h->g1_policy()->record_termination(i, term_ms, pss.term_attempts());
4663 }
4664 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4665 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4666
4667 // Clean up any par-expanded rem sets.
4668 HeapRegionRemSet::par_cleanup();
4669
4670 if (ParallelGCVerbose) {
4671 MutexLocker x(stats_lock());
4672 pss.print_termination_stats(i);
4673 }
4674
4675 assert(pss.refs()->is_empty(), "should be empty");
4676 double end_time_ms = os::elapsedTime() * 1000.0;
4677 _g1h->g1_policy()->record_gc_worker_end_time(i, end_time_ms);
4678 }
4679 };
4680
4681 // *** Common G1 Evacuation Stuff
4682
4683 // This method is run in a GC worker.
4684
4685 void
4686 G1CollectedHeap::
4687 g1_process_strong_roots(bool collecting_perm_gen,
4688 SharedHeap::ScanningOption so,
4689 OopClosure* scan_non_heap_roots,
4690 OopsInHeapRegionClosure* scan_rs,
4691 OopsInGenClosure* scan_perm,
4692 int worker_i) {
4693 // First scan the strong roots, including the perm gen.
4694 double ext_roots_start = os::elapsedTime();
4695 double closure_app_time_sec = 0.0;
4696
4697 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4698 BufferingOopsInGenClosure buf_scan_perm(scan_perm);
4699 buf_scan_perm.set_generation(perm_gen());
4700
4701 // Walk the code cache w/o buffering, because StarTask cannot handle
4702 // unaligned oop locations.
4703 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, /*do_marking=*/ true);
4704
4705 process_strong_roots(false, // no scoping; this is parallel code
4706 collecting_perm_gen, so,
4707 &buf_scan_non_heap_roots,
4708 &eager_scan_code_roots,
4709 &buf_scan_perm);
4710
4711 // Finish up any enqueued closure apps.
4712 buf_scan_non_heap_roots.done();
4713 buf_scan_perm.done();
4714 double ext_roots_end = os::elapsedTime();
4715 g1_policy()->reset_obj_copy_time(worker_i);
4716 double obj_copy_time_sec =
4717 buf_scan_non_heap_roots.closure_app_seconds() +
4718 buf_scan_perm.closure_app_seconds();
4719 g1_policy()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4720 double ext_root_time_ms =
4721 ((ext_roots_end - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4722 g1_policy()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4723
4724 // Scan strong roots in mark stack.
4725 if (!_process_strong_tasks->is_task_claimed(G1H_PS_mark_stack_oops_do)) {
4726 concurrent_mark()->oops_do(scan_non_heap_roots);
4727 }
4728 double mark_stack_scan_ms = (os::elapsedTime() - ext_roots_end) * 1000.0;
4729 g1_policy()->record_mark_stack_scan_time(worker_i, mark_stack_scan_ms);
4730
4731 // XXX What should this be doing in the parallel case?
4732 g1_policy()->record_collection_pause_end_CH_strong_roots();
4733 // Now scan the complement of the collection set.
4734 if (scan_rs != NULL) {
4735 g1_rem_set()->oops_into_collection_set_do(scan_rs, worker_i);
4736 }
4737 // Finish with the ref_processor roots.
4738 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4739 // We need to treat the discovered reference lists as roots and
4740 // keep entries (which are added by the marking threads) on them
4741 // live until they can be processed at the end of marking.
4742 ref_processor()->weak_oops_do(scan_non_heap_roots);
4743 ref_processor()->oops_do(scan_non_heap_roots);
4744 }
4745 g1_policy()->record_collection_pause_end_G1_strong_roots();
4746 _process_strong_tasks->all_tasks_completed();
4747 }
4748
4749 void
4750 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure,
4751 OopClosure* non_root_closure) {
4752 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4753 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs, non_root_closure);
4754 }
4755
4756
4757 class SaveMarksClosure: public HeapRegionClosure {
4758 public:
4759 bool doHeapRegion(HeapRegion* r) {
4760 r->save_marks();
4761 return false;
4762 }
4763 };
4764
4765 void G1CollectedHeap::save_marks() {
4766 if (!CollectedHeap::use_parallel_gc_threads()) {
4767 SaveMarksClosure sm;
4768 heap_region_iterate(&sm);
4769 }
4770 // We do this even in the parallel case
4771 perm_gen()->save_marks();
4772 }
4773
4774 void G1CollectedHeap::evacuate_collection_set() {
4775 set_evacuation_failed(false);
4776
4777 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4778 concurrent_g1_refine()->set_use_cache(false);
4779 concurrent_g1_refine()->clear_hot_cache_claimed_index();
4780
4781 int n_workers = (ParallelGCThreads > 0 ? workers()->total_workers() : 1);
4782 set_par_threads(n_workers);
4783 G1ParTask g1_par_task(this, n_workers, _task_queues);
4784
4785 init_for_evac_failure(NULL);
4786
4787 rem_set()->prepare_for_younger_refs_iterate(true);
4788
4789 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4790 double start_par = os::elapsedTime();
4791 if (G1CollectedHeap::use_parallel_gc_threads()) {
4792 // The individual threads will set their evac-failure closures.
4793 StrongRootsScope srs(this);
4794 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
4795 workers()->run_task(&g1_par_task);
4796 } else {
4797 StrongRootsScope srs(this);
4798 g1_par_task.work(0);
4799 }
4800
4801 double par_time = (os::elapsedTime() - start_par) * 1000.0;
4802 g1_policy()->record_par_time(par_time);
4803 set_par_threads(0);
4804 // Is this the right thing to do here? We don't save marks
4805 // on individual heap regions when we allocate from
4806 // them in parallel, so this seems like the correct place for this.
4807 retire_all_alloc_regions();
4808
4809 // Weak root processing.
4810 // Note: when JSR 292 is enabled and code blobs can contain
4811 // non-perm oops then we will need to process the code blobs
4812 // here too.
4813 {
4814 G1IsAliveClosure is_alive(this);
4815 G1KeepAliveClosure keep_alive(this);
4816 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4817 }
4818 release_gc_alloc_regions(false /* totally */);
4819 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4820
4821 concurrent_g1_refine()->clear_hot_cache();
4822 concurrent_g1_refine()->set_use_cache(true);
4823
4824 finalize_for_evac_failure();
4825
4826 // Must do this before removing self-forwarding pointers, which clears
4827 // the per-region evac-failure flags.
4828 concurrent_mark()->complete_marking_in_collection_set();
4829
4830 if (evacuation_failed()) {
4831 remove_self_forwarding_pointers();
4832 if (PrintGCDetails) {
4833 gclog_or_tty->print(" (to-space overflow)");
4834 } else if (PrintGC) {
4835 gclog_or_tty->print("--");
4836 }
4837 }
4838
4839 if (G1DeferredRSUpdate) {
4840 RedirtyLoggedCardTableEntryFastClosure redirty;
4841 dirty_card_queue_set().set_closure(&redirty);
4842 dirty_card_queue_set().apply_closure_to_all_completed_buffers();
4843
4844 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4845 dcq.merge_bufferlists(&dirty_card_queue_set());
4846 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4847 }
4848 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
4849 }
4850
4851 void G1CollectedHeap::free_region_if_empty(HeapRegion* hr,
4852 size_t* pre_used,
4853 FreeRegionList* free_list,
4854 HumongousRegionSet* humongous_proxy_set,
4855 HRRSCleanupTask* hrrs_cleanup_task,
4856 bool par) {
4857 if (hr->used() > 0 && hr->max_live_bytes() == 0 && !hr->is_young()) {
4858 if (hr->isHumongous()) {
4859 assert(hr->startsHumongous(), "we should only see starts humongous");
4860 free_humongous_region(hr, pre_used, free_list, humongous_proxy_set, par);
4861 } else {
4862 free_region(hr, pre_used, free_list, par);
4863 }
4864 } else {
4865 hr->rem_set()->do_cleanup_work(hrrs_cleanup_task);
4866 }
4867 }
4868
4869 void G1CollectedHeap::free_region(HeapRegion* hr,
4870 size_t* pre_used,
4871 FreeRegionList* free_list,
4872 bool par) {
4873 assert(!hr->isHumongous(), "this is only for non-humongous regions");
4874 assert(!hr->is_empty(), "the region should not be empty");
4875 assert(free_list != NULL, "pre-condition");
4876
4877 *pre_used += hr->used();
4878 hr->hr_clear(par, true /* clear_space */);
4879 free_list->add_as_head(hr);
4880 }
4881
4882 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4883 size_t* pre_used,
4884 FreeRegionList* free_list,
4885 HumongousRegionSet* humongous_proxy_set,
4886 bool par) {
4887 assert(hr->startsHumongous(), "this is only for starts humongous regions");
4888 assert(free_list != NULL, "pre-condition");
4889 assert(humongous_proxy_set != NULL, "pre-condition");
4890
4891 size_t hr_used = hr->used();
4892 size_t hr_capacity = hr->capacity();
4893 size_t hr_pre_used = 0;
4894 _humongous_set.remove_with_proxy(hr, humongous_proxy_set);
4895 hr->set_notHumongous();
4896 free_region(hr, &hr_pre_used, free_list, par);
4897
4898 int i = hr->hrs_index() + 1;
4899 size_t num = 1;
4900 while ((size_t) i < n_regions()) {
4901 HeapRegion* curr_hr = _hrs->at(i);
4902 if (!curr_hr->continuesHumongous()) {
4903 break;
4904 }
4905 curr_hr->set_notHumongous();
4906 free_region(curr_hr, &hr_pre_used, free_list, par);
4907 num += 1;
4908 i += 1;
4909 }
4910 assert(hr_pre_used == hr_used,
4911 err_msg("hr_pre_used: "SIZE_FORMAT" and hr_used: "SIZE_FORMAT" "
4912 "should be the same", hr_pre_used, hr_used));
4913 *pre_used += hr_pre_used;
4914 }
4915
4916 void G1CollectedHeap::update_sets_after_freeing_regions(size_t pre_used,
4917 FreeRegionList* free_list,
4918 HumongousRegionSet* humongous_proxy_set,
4919 bool par) {
4920 if (pre_used > 0) {
4921 Mutex* lock = (par) ? ParGCRareEvent_lock : NULL;
4922 MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
4923 assert(_summary_bytes_used >= pre_used,
4924 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" "
4925 "should be >= pre_used: "SIZE_FORMAT,
4926 _summary_bytes_used, pre_used));
4927 _summary_bytes_used -= pre_used;
4928 }
4929 if (free_list != NULL && !free_list->is_empty()) {
4930 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4931 _free_list.add_as_head(free_list);
4932 }
4933 if (humongous_proxy_set != NULL && !humongous_proxy_set->is_empty()) {
4934 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4935 _humongous_set.update_from_proxy(humongous_proxy_set);
4936 }
4937 }
4938
4939 void G1CollectedHeap::dirtyCardsForYoungRegions(CardTableModRefBS* ct_bs, HeapRegion* list) {
4940 while (list != NULL) {
4941 guarantee( list->is_young(), "invariant" );
4942
4943 HeapWord* bottom = list->bottom();
4944 HeapWord* end = list->end();
4945 MemRegion mr(bottom, end);
4946 ct_bs->dirty(mr);
4947
4948 list = list->get_next_young_region();
4949 }
4950 }
4951
4952
4953 class G1ParCleanupCTTask : public AbstractGangTask {
4954 CardTableModRefBS* _ct_bs;
4955 G1CollectedHeap* _g1h;
4956 HeapRegion* volatile _su_head;
4957 public:
4958 G1ParCleanupCTTask(CardTableModRefBS* ct_bs,
4959 G1CollectedHeap* g1h,
4960 HeapRegion* survivor_list) :
4961 AbstractGangTask("G1 Par Cleanup CT Task"),
4962 _ct_bs(ct_bs),
4963 _g1h(g1h),
4964 _su_head(survivor_list)
4965 { }
4966
4967 void work(int i) {
4968 HeapRegion* r;
4969 while (r = _g1h->pop_dirty_cards_region()) {
4970 clear_cards(r);
4971 }
4972 // Redirty the cards of the survivor regions.
4973 dirty_list(&this->_su_head);
4974 }
4975
4976 void clear_cards(HeapRegion* r) {
4977 // Cards for Survivor regions will be dirtied later.
4978 if (!r->is_survivor()) {
4979 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4980 }
4981 }
4982
4983 void dirty_list(HeapRegion* volatile * head_ptr) {
4984 HeapRegion* head;
4985 do {
4986 // Pop region off the list.
4987 head = *head_ptr;
4988 if (head != NULL) {
4989 HeapRegion* r = (HeapRegion*)
4990 Atomic::cmpxchg_ptr(head->get_next_young_region(), head_ptr, head);
4991 if (r == head) {
4992 assert(!r->isHumongous(), "Humongous regions shouldn't be on survivor list");
4993 _ct_bs->dirty(MemRegion(r->bottom(), r->end()));
4994 }
4995 }
4996 } while (*head_ptr != NULL);
4997 }
4998 };
4999
5000
5001 #ifndef PRODUCT
5002 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5003 G1CollectedHeap* _g1h;
5004 CardTableModRefBS* _ct_bs;
5005 public:
5006 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, CardTableModRefBS* ct_bs)
5007 : _g1h(g1h), _ct_bs(ct_bs) { }
5008 virtual bool doHeapRegion(HeapRegion* r) {
5009 if (r->is_survivor()) {
5010 _g1h->verify_dirty_region(r);
5011 } else {
5012 _g1h->verify_not_dirty_region(r);
5013 }
5014 return false;
5015 }
5016 };
5017
5018 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5019 // All of the region should be clean.
5020 CardTableModRefBS* ct_bs = (CardTableModRefBS*)barrier_set();
5021 MemRegion mr(hr->bottom(), hr->end());
5022 ct_bs->verify_not_dirty_region(mr);
5023 }
5024
5025 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5026 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5027 // dirty allocated blocks as they allocate them. The thread that
5028 // retires each region and replaces it with a new one will do a
5029 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5030 // not dirty that area (one less thing to have to do while holding
5031 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5032 // is dirty.
5033 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5034 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5035 ct_bs->verify_dirty_region(mr);
5036 }
5037
5038 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5039 CardTableModRefBS* ct_bs = (CardTableModRefBS*) barrier_set();
5040 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5041 verify_dirty_region(hr);
5042 }
5043 }
5044
5045 void G1CollectedHeap::verify_dirty_young_regions() {
5046 verify_dirty_young_list(_young_list->first_region());
5047 verify_dirty_young_list(_young_list->first_survivor_region());
5048 }
5049 #endif
5050
5051 void G1CollectedHeap::cleanUpCardTable() {
5052 CardTableModRefBS* ct_bs = (CardTableModRefBS*) (barrier_set());
5053 double start = os::elapsedTime();
5054
5055 // Iterate over the dirty cards region list.
5056 G1ParCleanupCTTask cleanup_task(ct_bs, this,
5057 _young_list->first_survivor_region());
5058
5059 if (ParallelGCThreads > 0) {
5060 set_par_threads(workers()->total_workers());
5061 workers()->run_task(&cleanup_task);
5062 set_par_threads(0);
5063 } else {
5064 while (_dirty_cards_region_list) {
5065 HeapRegion* r = _dirty_cards_region_list;
5066 cleanup_task.clear_cards(r);
5067 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5068 if (_dirty_cards_region_list == r) {
5069 // The last region.
5070 _dirty_cards_region_list = NULL;
5071 }
5072 r->set_next_dirty_cards_region(NULL);
5073 }
5074 // now, redirty the cards of the survivor regions
5075 // (it seemed faster to do it this way, instead of iterating over
5076 // all regions and then clearing / dirtying as appropriate)
5077 dirtyCardsForYoungRegions(ct_bs, _young_list->first_survivor_region());
5078 }
5079
5080 double elapsed = os::elapsedTime() - start;
5081 g1_policy()->record_clear_ct_time( elapsed * 1000.0);
5082 #ifndef PRODUCT
5083 if (G1VerifyCTCleanup || VerifyAfterGC) {
5084 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5085 heap_region_iterate(&cleanup_verifier);
5086 }
5087 #endif
5088 }
5089
5090 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
5091 size_t pre_used = 0;
5092 FreeRegionList local_free_list("Local List for CSet Freeing");
5093
5094 double young_time_ms = 0.0;
5095 double non_young_time_ms = 0.0;
5096
5097 // Since the collection set is a superset of the the young list,
5098 // all we need to do to clear the young list is clear its
5099 // head and length, and unlink any young regions in the code below
5100 _young_list->clear();
5101
5102 G1CollectorPolicy* policy = g1_policy();
5103
5104 double start_sec = os::elapsedTime();
5105 bool non_young = true;
5106
5107 HeapRegion* cur = cs_head;
5108 int age_bound = -1;
5109 size_t rs_lengths = 0;
5110
5111 while (cur != NULL) {
5112 assert(!is_on_master_free_list(cur), "sanity");
5113
5114 if (non_young) {
5115 if (cur->is_young()) {
5116 double end_sec = os::elapsedTime();
5117 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5118 non_young_time_ms += elapsed_ms;
5119
5120 start_sec = os::elapsedTime();
5121 non_young = false;
5122 }
5123 } else {
5124 double end_sec = os::elapsedTime();
5125 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5126 young_time_ms += elapsed_ms;
5127
5128 start_sec = os::elapsedTime();
5129 non_young = true;
5130 }
5131
5132 rs_lengths += cur->rem_set()->occupied();
5133
5134 HeapRegion* next = cur->next_in_collection_set();
5135 assert(cur->in_collection_set(), "bad CS");
5136 cur->set_next_in_collection_set(NULL);
5137 cur->set_in_collection_set(false);
5138
5139 if (cur->is_young()) {
5140 int index = cur->young_index_in_cset();
5141 guarantee( index != -1, "invariant" );
5142 guarantee( (size_t)index < policy->young_cset_length(), "invariant" );
5143 size_t words_survived = _surviving_young_words[index];
5144 cur->record_surv_words_in_group(words_survived);
5145
5146 // At this point the we have 'popped' cur from the collection set
5147 // (linked via next_in_collection_set()) but it is still in the
5148 // young list (linked via next_young_region()). Clear the
5149 // _next_young_region field.
5150 cur->set_next_young_region(NULL);
5151 } else {
5152 int index = cur->young_index_in_cset();
5153 guarantee( index == -1, "invariant" );
5154 }
5155
5156 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5157 (!cur->is_young() && cur->young_index_in_cset() == -1),
5158 "invariant" );
5159
5160 if (!cur->evacuation_failed()) {
5161 // And the region is empty.
5162 assert(!cur->is_empty(), "Should not have empty regions in a CS.");
5163 free_region(cur, &pre_used, &local_free_list, false /* par */);
5164 } else {
5165 cur->uninstall_surv_rate_group();
5166 if (cur->is_young())
5167 cur->set_young_index_in_cset(-1);
5168 cur->set_not_young();
5169 cur->set_evacuation_failed(false);
5170 }
5171 cur = next;
5172 }
5173
5174 policy->record_max_rs_lengths(rs_lengths);
5175 policy->cset_regions_freed();
5176
5177 double end_sec = os::elapsedTime();
5178 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5179 if (non_young)
5180 non_young_time_ms += elapsed_ms;
5181 else
5182 young_time_ms += elapsed_ms;
5183
5184 update_sets_after_freeing_regions(pre_used, &local_free_list,
5185 NULL /* humongous_proxy_set */,
5186 false /* par */);
5187 policy->record_young_free_cset_time_ms(young_time_ms);
5188 policy->record_non_young_free_cset_time_ms(non_young_time_ms);
5189 }
5190
5191 // This routine is similar to the above but does not record
5192 // any policy statistics or update free lists; we are abandoning
5193 // the current incremental collection set in preparation of a
5194 // full collection. After the full GC we will start to build up
5195 // the incremental collection set again.
5196 // This is only called when we're doing a full collection
5197 // and is immediately followed by the tearing down of the young list.
5198
5199 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5200 HeapRegion* cur = cs_head;
5201
5202 while (cur != NULL) {
5203 HeapRegion* next = cur->next_in_collection_set();
5204 assert(cur->in_collection_set(), "bad CS");
5205 cur->set_next_in_collection_set(NULL);
5206 cur->set_in_collection_set(false);
5207 cur->set_young_index_in_cset(-1);
5208 cur = next;
5209 }
5210 }
5211
5212 void G1CollectedHeap::set_free_regions_coming() {
5213 if (G1ConcRegionFreeingVerbose) {
5214 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5215 "setting free regions coming");
5216 }
5217
5218 assert(!free_regions_coming(), "pre-condition");
5219 _free_regions_coming = true;
5220 }
5221
5222 void G1CollectedHeap::reset_free_regions_coming() {
5223 {
5224 assert(free_regions_coming(), "pre-condition");
5225 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5226 _free_regions_coming = false;
5227 SecondaryFreeList_lock->notify_all();
5228 }
5229
5230 if (G1ConcRegionFreeingVerbose) {
5231 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
5232 "reset free regions coming");
5233 }
5234 }
5235
5236 void G1CollectedHeap::wait_while_free_regions_coming() {
5237 // Most of the time we won't have to wait, so let's do a quick test
5238 // first before we take the lock.
5239 if (!free_regions_coming()) {
5240 return;
5241 }
5242
5243 if (G1ConcRegionFreeingVerbose) {
5244 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5245 "waiting for free regions");
5246 }
5247
5248 {
5249 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5250 while (free_regions_coming()) {
5251 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5252 }
5253 }
5254
5255 if (G1ConcRegionFreeingVerbose) {
5256 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
5257 "done waiting for free regions");
5258 }
5259 }
5260
5261 size_t G1CollectedHeap::n_regions() {
5262 return _hrs->length();
5263 }
5264
5265 size_t G1CollectedHeap::max_regions() {
5266 return
5267 (size_t)align_size_up(max_capacity(), HeapRegion::GrainBytes) /
5268 HeapRegion::GrainBytes;
5269 }
5270
5271 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5272 assert(heap_lock_held_for_gc(),
5273 "the heap lock should already be held by or for this thread");
5274 _young_list->push_region(hr);
5275 g1_policy()->set_region_short_lived(hr);
5276 }
5277
5278 class NoYoungRegionsClosure: public HeapRegionClosure {
5279 private:
5280 bool _success;
5281 public:
5282 NoYoungRegionsClosure() : _success(true) { }
5283 bool doHeapRegion(HeapRegion* r) {
5284 if (r->is_young()) {
5285 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
5286 r->bottom(), r->end());
5287 _success = false;
5288 }
5289 return false;
5290 }
5291 bool success() { return _success; }
5292 };
5293
5294 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5295 bool ret = _young_list->check_list_empty(check_sample);
5296
5297 if (check_heap) {
5298 NoYoungRegionsClosure closure;
5299 heap_region_iterate(&closure);
5300 ret = ret && closure.success();
5301 }
5302
5303 return ret;
5304 }
5305
5306 void G1CollectedHeap::empty_young_list() {
5307 assert(heap_lock_held_for_gc(),
5308 "the heap lock should already be held by or for this thread");
5309 assert(g1_policy()->in_young_gc_mode(), "should be in young GC mode");
5310
5311 _young_list->empty_list();
5312 }
5313
5314 bool G1CollectedHeap::all_alloc_regions_no_allocs_since_save_marks() {
5315 bool no_allocs = true;
5316 for (int ap = 0; ap < GCAllocPurposeCount && no_allocs; ++ap) {
5317 HeapRegion* r = _gc_alloc_regions[ap];
5318 no_allocs = r == NULL || r->saved_mark_at_top();
5319 }
5320 return no_allocs;
5321 }
5322
5323 void G1CollectedHeap::retire_all_alloc_regions() {
5324 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {
5325 HeapRegion* r = _gc_alloc_regions[ap];
5326 if (r != NULL) {
5327 // Check for aliases.
5328 bool has_processed_alias = false;
5329 for (int i = 0; i < ap; ++i) {
5330 if (_gc_alloc_regions[i] == r) {
5331 has_processed_alias = true;
5332 break;
5333 }
5334 }
5335 if (!has_processed_alias) {
5336 retire_alloc_region(r, false /* par */);
5337 }
5338 }
5339 }
5340 }
5341
5342 // Done at the start of full GC.
5343 void G1CollectedHeap::tear_down_region_lists() {
5344 _free_list.remove_all();
5345 }
5346
5347 class RegionResetter: public HeapRegionClosure {
5348 G1CollectedHeap* _g1h;
5349 FreeRegionList _local_free_list;
5350
5351 public:
5352 RegionResetter() : _g1h(G1CollectedHeap::heap()),
5353 _local_free_list("Local Free List for RegionResetter") { }
5354
5355 bool doHeapRegion(HeapRegion* r) {
5356 if (r->continuesHumongous()) return false;
5357 if (r->top() > r->bottom()) {
5358 if (r->top() < r->end()) {
5359 Copy::fill_to_words(r->top(),
5360 pointer_delta(r->end(), r->top()));
5361 }
5362 } else {
5363 assert(r->is_empty(), "tautology");
5364 _local_free_list.add_as_tail(r);
5365 }
5366 return false;
5367 }
5368
5369 void update_free_lists() {
5370 _g1h->update_sets_after_freeing_regions(0, &_local_free_list, NULL,
5371 false /* par */);
5372 }
5373 };
5374
5375 // Done at the end of full GC.
5376 void G1CollectedHeap::rebuild_region_lists() {
5377 // This needs to go at the end of the full GC.
5378 RegionResetter rs;
5379 heap_region_iterate(&rs);
5380 rs.update_free_lists();
5381 }
5382
5383 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5384 _refine_cte_cl->set_concurrent(concurrent);
5385 }
5386
5387 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5388 HeapRegion* hr = heap_region_containing(p);
5389 if (hr == NULL) {
5390 return is_in_permanent(p);
5391 } else {
5392 return hr->is_in(p);
5393 }
5394 }
5395
5396 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5397 bool force) {
5398 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5399 assert(!force || g1_policy()->can_expand_young_list(),
5400 "if force is true we should be able to expand the young list");
5401 if (force || !g1_policy()->is_young_list_full()) {
5402 HeapRegion* new_alloc_region = new_region(word_size,
5403 false /* do_expand */);
5404 if (new_alloc_region != NULL) {
5405 g1_policy()->update_region_num(true /* next_is_young */);
5406 set_region_short_lived_locked(new_alloc_region);
5407 g1mm()->update_eden_counters();
5408 return new_alloc_region;
5409 }
5410 }
5411 return NULL;
5412 }
5413
5414 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5415 size_t allocated_bytes) {
5416 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5417 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
5418
5419 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5420 _summary_bytes_used += allocated_bytes;
5421 }
5422
5423 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
5424 bool force) {
5425 return _g1h->new_mutator_alloc_region(word_size, force);
5426 }
5427
5428 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
5429 size_t allocated_bytes) {
5430 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
5431 }
5432
5433 // Heap region set verification
5434
5435 class VerifyRegionListsClosure : public HeapRegionClosure {
5436 private:
5437 HumongousRegionSet* _humongous_set;
5438 FreeRegionList* _free_list;
5439 size_t _region_count;
5440
5441 public:
5442 VerifyRegionListsClosure(HumongousRegionSet* humongous_set,
5443 FreeRegionList* free_list) :
5444 _humongous_set(humongous_set), _free_list(free_list),
5445 _region_count(0) { }
5446
5447 size_t region_count() { return _region_count; }
5448
5449 bool doHeapRegion(HeapRegion* hr) {
5450 _region_count += 1;
5451
5452 if (hr->continuesHumongous()) {
5453 return false;
5454 }
5455
5456 if (hr->is_young()) {
5457 // TODO
5458 } else if (hr->startsHumongous()) {
5459 _humongous_set->verify_next_region(hr);
5460 } else if (hr->is_empty()) {
5461 _free_list->verify_next_region(hr);
5462 }
5463 return false;
5464 }
5465 };
5466
5467 void G1CollectedHeap::verify_region_sets() {
5468 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5469
5470 // First, check the explicit lists.
5471 _free_list.verify();
5472 {
5473 // Given that a concurrent operation might be adding regions to
5474 // the secondary free list we have to take the lock before
5475 // verifying it.
5476 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5477 _secondary_free_list.verify();
5478 }
5479 _humongous_set.verify();
5480
5481 // If a concurrent region freeing operation is in progress it will
5482 // be difficult to correctly attributed any free regions we come
5483 // across to the correct free list given that they might belong to
5484 // one of several (free_list, secondary_free_list, any local lists,
5485 // etc.). So, if that's the case we will skip the rest of the
5486 // verification operation. Alternatively, waiting for the concurrent
5487 // operation to complete will have a non-trivial effect on the GC's
5488 // operation (no concurrent operation will last longer than the
5489 // interval between two calls to verification) and it might hide
5490 // any issues that we would like to catch during testing.
5491 if (free_regions_coming()) {
5492 return;
5493 }
5494
5495 // Make sure we append the secondary_free_list on the free_list so
5496 // that all free regions we will come across can be safely
5497 // attributed to the free_list.
5498 append_secondary_free_list_if_not_empty_with_lock();
5499
5500 // Finally, make sure that the region accounting in the lists is
5501 // consistent with what we see in the heap.
5502 _humongous_set.verify_start();
5503 _free_list.verify_start();
5504
5505 VerifyRegionListsClosure cl(&_humongous_set, &_free_list);
5506 heap_region_iterate(&cl);
5507
5508 _humongous_set.verify_end();
5509 _free_list.verify_end();
5510 }